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iN3minN QNV n^i3a 
COVER PHOTOGRAPH:

The Landsat image on the cover shows the extent of the flood 

plain in the Apalachicola River Basin, Florida. The dark color of the 

flood plain is caused by the low reflectance from flood waters. The 

200-m wide river is barely visible in the center of the 3.2 to 8.0-kmwide flood plain. The Apalachicola River flows from Lake Seminole 

(at the top), 171 km south, to Apalachicola Bay (near the bottom of 

the scene). The numerous white squares near the top of the scene are 

agricultural fields ir Florida and Alabama. The large red area east of 

the river is pine forest (Apalachicola National Forest). The faint 

brown color on the birdsfoot delta at the river mouth is marsh. The 

light blue colors near the beaches at the bottom of the scene are a combination of shallow areas and areas with high suspended sediments 

caused by ocean currents.

The false-color composite was obtained on February 6, 1977, by 

a Landsat multispectral scanner and includes bands 4, 5, and 7. The 

scene ID is 2746-15190, and more information on this and other 

satellite images is available through the U.S. Geological Survey, 

EROS Data Center, Sioux Falls, S. Dak., 57198.
Chapter C

NUTRIENT AND DETRITUS TRANSPORT 

IN THE APALACHICOLA RIVER, 

FLORIDA

By HAROLD C. MATTRAW, JR., and JOHN F. ELDER

U.S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2196-C 

Apalachicola River Quality Assessment
UNITED STATES DEPARTMENT OF THE INTERIOR 

WILLIAM P. CLARK, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE: 1984

For sale by Distribution Branch 

Text Products Section 

U.S. Geological Survey 

604 South Pickett Street 

Alexandria, Virginia 22304

Library of Congress Cataloging in Publication Data

Mattraw, H. C.

Nutrient and detritus transport in the Apalachicola River, Florida.

(U.S. Geological water-supply paper; 2196-C)

Bibliography: p.

Supt. of Docs, no.: I 19.13:2196-C 

1. Sediment transport Florida-Apalachicola River Watershed. 2. Detritus Florida-Apalachicola River Watershed. 3. I.

Elder, John F. II Title. III. Series.

GB850.M37 1984 551.48'3'097559 83-600181
FOREWORD

The Apalachicola River Quality Assessment was designed to evaluate the numerous factors that influence the nutrient and detrital yield of the river to Apalachicola 

Bay. The excellent hydrologic gaging system on the Apalachicola River permitted 

subdivision of the flood plain into three input-output units. The systematic analysis 

of nutrient sources, transport, and yields in the flood plain required new study 

techniques and data collection methods for (1) river and wetland hydrology, (2) 

tree species abundance and distribution, (3) leaf-litter production and decomposition, 

and (4) nutrient and detritus transport. These factors are the focus of separate WaterSupply Papers in the series (number 2196) dealing with the Apalachicola River 

Quality Assessment. Nutrient and detritus transport and ultimate yields are discussed 

in this paper. Extensive information from the previous papers is cited as necessary 

to develop a cogent scenario for nutrient and detritus yield.

The main purpose of this characterization of nutrient and detritus sources and 

mechanisms is to provide a quantitative methodology for evaluating densely forested 

bottom-land hardwood swamps. The Apalachicola flood plain has demonstrable 

importance to a highly productive Apalachicola estuary. A more accurate appraisal 

of wetland functions is available through the quantification of the flood-plain treecommunity nutrient and detritus supply to a commercially valuable mariculture. The 

approach used in the Apalachicola River Quality Assessment is an attempt to better 

understand the wetland function and to begin to quantify the roles of specific components, such as flood-plain leaf-litter fall.

Philip Cohen

Chief Hydrologist

U.S. Geological Survey

in
CONTENTS

Foreword 111 

Abstract Cl 

Introduction Cl

Purpose and objectives of the Apalachicola River Quality Assessment Cl 

Setting C3 

Background C7 

Conceptual design C8 

Approach and methods C8 

Subbasin approach C8

Intensive data-collection transect approach C8 

Discharge approach C9 

Water-quality sampling approach C9

Sample location and frequency C9

Sample handling Cll

Bulk precipitation approach and method C14 

Ground-water component CIS 

Detritus methods CIS

Suspended detritus CIS

Bottom-load detritus C16

Flood-plain detritus C16 

Net collection C16 

Plastic-sheet collection C17 

Data handling C17 

Results C21

Seven hydrologic periods C21 

Water budget C22

Streamflow C24

Precipitation C24

Ground water C25

Chipola River inflow C26

Evapotranspiration C27

Overall water budget C28 

Nutrient concentrations C29

Nutrient concentrations in the river C29

Bulk-precipitation concentrations C29

Ground-water chemistry C30

Chipola River C31 

Nutrient transport C31

Nutrient transport residual C33

Transport, 1979-80 C33 

Detritus C38

Concentrations C38

Transport C38

Flood-plain transport C38

Deposition on flood-plain floor C38 

Error analysis C42

Water budget C42

Nutrient and detritus concentrations C43

Transport C44

Contents
Discussion C44

Flood-plain role in nutrient transport C44

River basin nutrient yield C47

Sources of nutrients C52

Flood-plain detritus contributions C52

Flood-plain-net estimate of detritus C53

Plastic-sheet estimate of detritus C53

Significance of flood-plain-net and plastic-sheet estimates C54

Nutrient yields for the Apalachicola-Chattahoochee-Flint River system C54

Long-term factors influencing nutrient transport C55 

Summary C56 

Selected references C57

Supplementary data I Flood-plain detritus data C60 

Supplementary data II Deposition on plastic sheets C61 

Metric conversion factors C62

FIGURES

1. Maps of the drainage basins of the Apalachicola, Chattahoochee, and Flint Rivers 

in Alabama, Florida, and Georgia (left) and the Apalachicola and Chipola Rivers 

showing the flood plain and gaging station drainage divides (right) C2

2. Photograph of Jim Woodruff lock and dam C4

3. Map of Dead Lake, Chipola Cutoff, and Apalachicola River near Wewahitchka, 

Florida C5

4. Map of Apalachicola River, Brickyard Cutoff, and Brothers River near Brickyard 

Landing C6

5. Map of Apalachicola River subbasin components and gaging locations CIO

6. Photograph showing locations of litter-fall collection plots and water-level observation 

sites near the Sweetwater transect C12

7. Photograph showing locations of litter-fall collection plots, water-level observation 

sites, and rainfall gage near the Brickyard transect C13

8. Diagram of water-quality sample handling procedures CIS

9. Photograph of bulk precipitation apparatus used for collection of total carbon, 

total nitrogen, and total phosphorus samples C17

10. Map showing locations of National Weather Service and U.S. Geological Survey 

rain gages and bulk precipitation sample collectors in the Apalachicola basin, 

Florida CIS

11. Map of the potentiometric surface of the Floridan aquifer in May 1976 C19

12. Photograph of sampling apparatus used for collection of bottom-load 

particulate organic material C20

13. Histogram showing results of cross-sectional sampling on July 2, 1979 C21

14. Photographs of flood-plain detritus net used to measure transported forest 

litter C22

15. Diagram of major steps in data collection and handling C23

16. Diagrammatic representation of Apalachicola water budget C24

17. Graph of mean nutrient concentrations for the period February 1979 

through July 1980 at the four main river collection stations 

with standard error bars C30

18. Probability plots of total carbon, total nitrogen, and total

phosphorus concentrations in bulk precipitation samples C30

19. Graph of total organic carbon concentrations, mean sample

interval discharge, and seven hydrologic periods at Sumatra C32

20. Graph of paniculate organic carbon concentrations C39

21. Graph of bottom paniculate organic carbon concentrations C40

22. Graph of annual paniculate organic carbon transport C41

VI Contents
23. Graph of annual nutrient transport at four Apalachicola

River sites and the Chipola River Outlet at Dead Lake, showing 

error ranges C45

24. Graph of cumulative carbon transport in the Apalachicola River 

basin from June 3, 1979, through June 2, 1980 C48

25. Graph of cumulative nitrogen transport in the Apalachicola River 

basin from June 3, 1979, through June 2, 1980 C49

26. Graph of cumulative phosphorus transport in the Apalachicola River 

basin from June 3, 1979, through June 2, 1980 C50

27. Graph of observed versus constant rate transport of five

paniculate organic carbon fractions in the Apalachicola River 

basin from June 3, 1979, through June 2, 1980 C51

TABLES

1. Abundance of 18 tree species in the Apalachicola River flood plain C6

2. Species composition and frequency of five major tree communities in the 

Apalachicola River flood plain C7

3. Ten dominant species of invertebrates collected by otter trawl in Apalachicola 

Bay C7

4. Stage-discharge gage stations on the Apalachicola River, Florida C9

5. Data-collection procedures used in determining nutrient and detritus transport Cll

6. Water-quality sample collection dates at the major river-gaging stations CI4

7. Analytical techniques used in the determination of chemical and physical characteristics of water samples C16

8. Flow volumes by gaging sites and the seven periods C24

9. Precipitation in the seven periods and the Apalachicola basins from June 3, 

1979, through June 2, 1980 C25

10. Mean discharge per unit watershed area based on low-flow measurements C26

11. Inflow from Chipola River at Dead Lake, June 3, 1979, through June 2, 1980 C27

12. Estimates of annual evapotranspiration (ET) in Apalachicola subbasins, June 3, 

1979, through June 2, 1980 C27

13. Water budget in the upper subbasin (Chattahoochee-Blountstown),by periods, 

June 3, 1979, through June 2, 1980 C28

14. Water budget in the middle subbasin (Blountstown-Wewahitchka), by periods, 

June 3, 1979, through June 2, 1980 C28

15. Water budget in the lower subbasin (Wewahitchka- Sumatra), by periods, June 

3, 1979, through June 2, 1980 C29

16. Water budget in the Apalachicola basin (Chattahoochee-Sumatra), by periods, 

June 3, 1979, through June 2, 1980 C29

17. Mean nutrient concentrations and chemical characteristics of ground water compared with water of the Apalachicola River near Blountstown and the Chipola 

River near Wewahitchka C31

18. Total carbon transport in the upper subbasin, by periods, June 3, 1979, through 

June 2, 1980 C34

19. Total carbon transport in the middle subbasin, by periods, June 3, 1979, through 

June 2, 1980 C34

20. Total carbon transport in the lower subbasin, by periods, June 3, 1979, through 

June 2, 1980 C34

21. Total carbon transport in the Apalachicola basin between Chattahoochee and 

Sumatra, by periods, June 3, 1979, through June 2, 1980 C35

22. Total nitrogen transport in the upper subbasin, by periods, June 3, 1979, through 

June 2, 1980 C35

23. Total nitrogen transport in the middle subbasin, by periods, June 3, 1979, 

through June 2, 1980 C35

Contents VII
24. Total nitrogen transport in the lower subbasin, by periods, June 3, 1979, through 

June 2, 1980 C36

25. Total nitrogen transport in the Apalachicola basin between Chattahpochee and 

Sumatra, by periods, June 3, 1979, through June 2, 1980 C36

26. Total phosphorus transport in the upper subbasin, by periods, June 3, 1979, 

through June 2, 1980 C36

27. Total phosphorus transport in the middle subbasin, by periods, June 3, 1979, 

through June 2, 1980 C37

28. Total phosphorus transport in the lower subbasin, by periods, June 3, 1979, 

through June 2, 1980 C37

29. Total phosphorus transport in the Apalachicola basin between Chattahoochee 

and Sumatra, by periods, June 3, 1979, through June 2, 1980 C37

30. Daily detritus fraction transport at Sumatra, by periods, June 3, 1979, through 

June 2, 1980 C42

31. Deposition of material during 9 to 11 months on plastic sheets randomly located 

in intensive plots C43

32. Nutrient yields, on an areal basis, for various drainage areas of the ApalachicolaChattahoochee-Flint River system C55

VIII Contents
Nutrient and Detritus Transport in the 

Apalachicola River, Florida

Qy Harold C. Mattraw, Jr., and John F. Elder

Abstract

The Apalachicola River in northwest Florida flows 172 

kilometers southward from Jim Woodruff Dam near the 

Florida-Georgia border to Apalachicola Bay on the Gulf of 

Mexico. The basin is composed of two 3,100-squarekilometer subbasins, the Chipola and the Apalachicola. 

The Apalachicola subbasin includes a454-square-kilometer 

bottom-land hardwood flood plain that is relatively undeveloped. The flood plain contains more than 1,500trees per 

hectare that annually produce approximately 800 metric 

tons of litter fall per square kilometer. Spring floods of 

March and April 1980 carried 35,000 metric tons of particulate organic carbon derived from litter fall into Apalachicola 

Bay. The estuarine food web is predominantly detrital 

based and represents an important commercial source of 

oyster, shrimp, blue crab, and various species of fish.

The water budget of the Apalachicola basin is heavily 

dominated by streamflow. For a 1-year period in 1979-80, 

28.6 cubic kilometers of water flowed past the Sumatra 

gage on the lower river. Eighty percent of this volume 

flowed into the upper river near Chattahoochee, Fla., and 

11 percent was contributed by its major tributary, the 

Chipola River. Contributions from ground water and overland runoff were less than 10 percent.

Streamflow increases downstream were accompanied by equivalent increases in nitrogen and phosphorus transport. The nutrients were released to the river 

by the flood-plain vegetation, but also were subject to recycling. The increase in the amount of organic carbon 

transport downstream was greater than streamflow increases. The flood plain is an important source of organic 

carbon, especially in detrital form.

Several methods for measurement of detritus in the 

river and flood plain were developed and tested. The detritus data from the flood plain added semiquantitative evidence for transport of detritus from the flood plain to the 

river flow, probably accounting for most of the coarse particulate organic material carried by the river.

During the 1-year period of investigation, June 3, 

1979, through June 2,1980, 2.1 x 105 metric tons of organic 

carbon were transported from the river basin to the bay. 

Nitrogen and phosphorus transport during the same 

period amounted to 2.2 x 104 and 1.7 x 103 metric tons, respectively. On an areal basis, it was calculated that the

flood plain contributed 70 grams of organic carbon per 

square meter per year, 0.4 gram of nitrogen per square 

meter per year, and 0.5 gram of phosphorus per square 

meter per year. The flood plain acts as a source of detrital 

carbon, but for the solutes, nutrient release is approximately balanced by nutrient retention.

INTRODUCTION

Purpose and Objectives of the 

Apalachicola River Quality Assessment

The Apalachicola River Quality Assessment was initiated in 1978 as part of a national river quality assessment program of the U.S. Geological Survey. The purpose of the Apalachicola River Quality Assessment was to 

evaluate the importance of the Apalachicola River and its 

associated flood plain in supplying nutrients and organic 

detritus to Apalachicola Bay (fig. 1).

The specific goals of the Apalachicola River Quality 

Assessment were process oriented rather than problem 

oriented. Its primary purpose was to investigate river-wetland relations and controlling factors that influence the 

yield of nutrients and detritus to the bay. Emphasis was 

on processes that influence nutrient and detritus flow 

rather than on problems involving environmental disturbance or pollution. Special attention was given to methods 

development because ecological studies of large river-wetland systems have been rare and few methods particularly 

applicable to this type of study have been described.

The subtle but profound impact of hydrologic factors on tree-community distribution and on leaf-litter production and decomposition is difficult to document, and 

thoroughly documented methods of study are lacking. The 

more direct result of seasonal flooding the erosion of 

large quantities of nutrients and decaying leaf litter from 

the flood plain and transport into the river is more evident. However, methods for studying transport of large 

organic particles in the flood plain also lack documentation. Even the present (1980) techniques used to study

Nutrient and Detritus Transport in the Apalachicola River, Florida C1
85°I5' 85°00

33<

25 e

88° 84 e

EXPLANATION

APALACHICOLA RIVER 

DRAINAGE SYSTEM

0 100 200 KILOMETERS 

I______|______|

ALABAMA! 

~R_ORIDA

^f

(_ WEWAHITCHKA 

A 

29°45 -

Figure 1. The drainage basins of the Apalachicola, Chattahoochee, and Flint Rivers in Alabama, Florid

and the Apalachicola and Chipola Rivers showing the flood plain and gaging station drainage divides (r
particulate transport within the river lack standardization. 

To a large extent, the Apalachicola River Quality Assessment was designed to test methods with which to evaluate 

the influence of hydrologic factors on tree distribution, 

leaf-litter production, leaf-litter decomposition, and transport of nutrients and detritus. All of these methods were 

ultimately directed toward understanding the role of the 

flood plain in the nutrient and detritus yield to 

Apalachicola Bay.

The specific objectives of the Apalachicola River 

Quality Assessment were (Mattraw and Elder, 1980)

1. To determine the accumulation of trace elements and 

organic substances in benthic organisms and finegrained sediments;

2. To describe how tree distribution on the flood plain 

is related to the pattern of flooding (duration, level, 

and frequency);

3. To assess the importance of leaf production and decomposition on the flood plain to detritus and nutrient 

yields of the basin; and

4. To identify major sources of nutrients to the river system and to quantify transport of nutrients and organic 

detritus in various parts of the system.

The specific purpose of this report is to address the 

fourth objective by presenting the results of nutrient and 

detritus transport determinations. The results of transport 

are directly dependent on an analysis of the basin water 

budget. The water budget and nutrient transport calculations are for the 366-day period from June 3, 1979, 

through June 2, 1980. The area considered is the 3,100- 

square-kilometer Apalachicola River basin in northwest 

Florida. Important aspects discussed include methods of 

measurement, hydrologic features that affect nutrient 

flow, changes in nutrient and detritus concentration over 

space and time, and the efficiency of flood-plain litter-fall 

capture by the flood waters.

Throughout this report, the term "nutrients" refers to 

both suspended particulate and soluble or dissolved nitrogen, phosphorus, and organic carbon. "Detritus" refers to 

organic particulate matter that contains leachable nutrients 

as well as numerous other elements associated with 

biological tissues. A conceptual design, methods, results, 

and analysis of errors are presented for the nutrient and 

detritus transport from the Apalachicola basin.

Setting

The Apalachicola River winds 172 km through the 

northwest Florida Panhandle and empties into the Gulf of 

Mexico (fig. 1) through Apalachicola Bay. In 1954, the 

Jim Woodruff Dam was constructed 1.5 km downstream 

from the confluence of the Chattahoochee and Flint Rivers 

and became the upstream limit of the Apalachicola River. 

The reservoir behind the dam, 15,200 ha in area, was

filled by 1957. The entire Apalachicola-ChattahoocheeFlint River drainage basin is 50,800 km2 in area, encompassing parts of Georgia, Alabama, and Florida. The part 

below the dam, which drains to the Apalachicola River directly, has an area of 6,200 km2 .

Jim Woodruff Dam (fig. 2) was constructed by the 

U.S. Army Corps of Engineers primarily to facilitate navigation on the Chattahoochee and Flint Rivers. The dam 

has a navigation lock 25 m wide, with about 9 m of lift 

from the Apalachicola River into Lake Seminole. The 

dam also creates storage for a hydroelectric generating 

plant, which supplies a part of the power needs for the 

city of Chattahoochee and neighboring communities.

The only major tributary of the Apalachicola River 

below Jim Woodruff Dam is the Chipola River. The 

Chipola is constrained by a low-head, interlocking, sheetpile weir near Wewahitchka, Fla. (fig.3). The resulting 

pool is called Dead Lake. The drainage area of the 

Chipola River above Dead Lake is 3,100 km2 , exactly 

one-half of the drainage area of the entire Apalachicola 

basin. Immediately downstream from the weir, the 

Chipola is joined by Apalachicola River water flowing 

through the Chipola Cutoff distributary. These waters rejoin the main stem of the Apalachicola 21 km downstream.

A second major distributary channel of the investigated reach is located near the Sumatra gage at Brickyard 

Landing (fig. 4). The Brickyard Cutoff conveys water 

from the Apalachicola River to the Brothers River. The 

rating curve for the Sumatra gage is developed from measurements upstream of Brickyard Cutoff and, therefore, 

represents the total flow of-both channels.

Twelve km south of Brickyard Cutoff, the Brothers 

River joins the Apalachicola. The major part of the 

Apalachicola River flows 10 km south, where it joins the 

Jackson River and flows southeast into Apalachicola Bay. 

The U.S. Highway 98 bridge across the bay, near the 

mouth of the Apalachicola River, is used by the U.S. 

Army Corps of Engineers as the mile 0 for navigation purposes on the river.

The flood plain of the Apalachicola River is 454 

km2 in area, expanding from a width of 1 km near Chattahoochee to 8 km near Sumatra. The composition of the 

Apalachicola flood-plain tree community was estimated by 

Leitman and others (1983). Table 1 lists the 18 most commonly observed flood-plain species, in order of abundance. The data represent tree identification from eight 

cruise transects across the flood plain at widely spaced locations. Leitman and others (1983) recognized 5 major 

forest types (table 2) and 47 tree species.

Forest-litter production in the flood plain is potentially a major source of nutrients and organic matter in the 

Apalachicola system. The flood plain is heavily forested 

with bottom-land hardwoods dominated by Ogeechee and 

water tupelo (Nyssa ogeche, N. aquatica) and baldcypress

Nutrient and Detritus Transport in the Apalachicola River, Florida C3
Figure 2. Jim Woodruff lock and dam (view is to the north).

(Taxodium distichum). Many of these species are highly 

sensitive to the extent and duration of flooding. The vegetation annually produces tons of leaf litter and other organic matter which must be either reincorporated into the 

system or transported out of it. Once litter fall reaches the 

flood-plain floor, annual flooding of the forest accelerates 

decomposition and transport of materials from the flood 

plain to the main-stream channels (Elder and Cairns, 

1982).

Using litter-fall measurements collected at two 

transects between September 1979 and September 1980 

and forest type composition data from the eight cruise 

transects, Elder and Cairns (1982) calculated a mean annual litter production of 800 g/m2 . At this rate, the trees 

and vines of the 454-square-kilometer flood plain produce 

3.6x 105 metric tons of litter fall annually. Much of this 

material decomposes and is recycled to vegetation. It is 

assumed that some of the soluble decomposition products 

leach through the soil and enter the ground-water system. 

Another fraction is eroded by seasonal floods and is either 

redeposited on the flood plain or is captured by the river 

and carried to Apalachicola Bay. The proportion that is

transported by the seasonal flooding depends to a great extent on the magnitude and duration of the seasonal flooding. The residual nutrient content and particle size of the 

transported litter (detritus) are governed largely by the 

length of time between the litter fall and the flooding 

episode. The major litter-fall months in the Apalachicola 

flood plain are October and November (Elder and Cairns, 

1982). Peak flooding is normally between January and 

March.

Nutrients and detritus are transported into 

Apalachicola Bay, which has a complex trophic structure. 

In an exhaustive data-gathering program, Florida State 

University scientists (Livingston and others, 1974) are developing a data base that demonstrates the impacts of various physical, chemical, and biological factors on the estuarine ecosystem. The role of the river in affecting the 

salinity structure, in supplying nutrients to phytoplankton, 

and in providing detritus is well documented.

The relation between the river system and the bay 

contributes directly to the economic welfare of Franklin 

County. Oysters (Crassostrea virginica Gmelin) depend on 

an adequate nutrient supply to sustain their planktonic

C4 Apalachicola River Quality Assessment
85°28' 27' 26' 25* 24* 23* 22' 2l' 20* 19* 85°I8'

30° 10' -

WEWAHITCHKA GAGE

Figure 3. Dead Lake, Chipola Cutoff, and Apalachicola River near Wewahitchka, Florida.

Nutrient and Detritus Transport in the Apalachicola River, Florida C5
85°I9' 18' 17' 16' 85°I5'

29°58'

57'

56

55'

54

53'

52'

51'

29°50'

SUMATRA 

GAGE

0 I 2 KILOMETERS

.

Figure 4. Apalachicola River, Brickyard Cutoff, and 

Brothers River near Brickyard Landing.

food supply, and the periodic pulses of freshwater discourage predation by oyster drills (Labyrinthomysa 

marina) (Menzel and others, 1966). Oyster harvesting is 

the major industry of the county; the second and third 

most economically important commercial species of 

marine life are shrimp (Penaeus sp.) and blue crab (Callinectes sapidus). Both the shrimp and the crab are detrivores.

Extensive otter-trawl sampling of Apalachicola Bay 

organisms (Livingston and others, 1976) identified the 10 

dominant species of invertebrates (table 3). The most 

abundant, the white shrimp (Penaeus setiferus), uses the 

bay as a nursery ground and depends heavily on detritus 

and detritus-associated organisms. Five of the six most

Table 1. Abundance of 18 tree species in the Apalachicola

River flood plain 

[Modified from Leitmanand others, 1983]

Species

Water tupelo. ..............

Ogeechee tupelo ............

Baldcypress ...............

Carolina ash ...............

Blackgum. ................

Sweetgum ................

Overcup oak. ..............

Planer-tree ................

Green ash. ................

Water hickory. .............

Sugarberry ................

Diamond-leaf oak ...........

American elm ..............

American hornbeam. .........

Pumpkin ash1 ..............

Water oak ................

Red maple ................

Sweetbay. ................

Relative basal area

(in percent)

..... 29.9

..... 11.0

..... 10.6

..... 5.4

..... 5.0

..... 4.8

..... 3.2

..... 2.9

..... 2.9

..... 2.9

..... 2.8

..... 2.5

..... 2.4

. . . . . 2.0

. . . . . 1.9

. . . . . 1.8

. . . . . 1.5

. . . . . 1.0

1 Some trees identified as pumpkin ash may have been Carolina 

ash or green ash. Samaras (winged seeds) had dropped from the 

trees and seeds of all three species were mixed on the ground beneath the trees.

abundant species of invertebrates in Apalachicola Bay are 

benthic omnivores and depend heavily on detritus. Gravid 

female blue crabs from along the entire western coast of 

Florida migrate to the bay region to spawn (Oesterling and 

Evink, 1977). Juveniles apparently migrate into 

Apalachicola Bay. This pattern explains the abundance of 

juvenile blue crabs (table 3) observed by Livingston and 

others (1976).

Fish are also abundant in Apalachicola Bay. In general, their connection to detritus is indirect; ultimately, 

however, detritus is just as vital to the fish as it is to the 

invertebrates (Livingston and others, 1976). Decayed litter 

material is colonized by fungi, algae, and bacteria, which 

are grazed by protozoans. Isopods, amphipods, and decapods use the attached and associated organisms for food 

and the larger leaf and litter particles for shelter. Many 

fish feed on these small marine organisms. The higher 

trophic levels are thus dependent on an abundant nutrient 

and detrital supply at the base of the food web. Although 

the complex physical, chemical, and biological interactions of the bay estuarine system are incompletely understood, the river-derived nutrients and detritus are recognized as essential to the maintenance of the diverse 

ecosystem.

C6 Apalachicola River Quality Assessment
Table 2. Species composition and frequency of five major 

tree communities in the Apalachicola River flood plain

[Modified from Leitman and others, 1983]

Forest 

types

A. . .

Predominant 

species

Sweetgum 

Sugarberry 

Water oak

American

hornbeam 

Possumhaw

Associated 

species

Diamond -leaf oak 

Green ash 

American elm

American

sycamore 

Water hickory

Percentage 

of 223 

cruisetransect

plots

21

D

U

Water hickory 

Green ash 

Overcup oak 

Diamond-leaf oak 

Sweetgum 

American elm

Water tupelo 

Ogeechee tupelo 

Baldcypress 

Blackgum 

Carolina ash 

Planertree

Water tupelo 

Blackgum 

Ogeechee tupelo 

Baldcypress 

Carolina ash 

Pumpkin ash 

Planertree 

Sweetbay

Water tupelo 

Baldcypress 

Carolina ash 

Planertree

Undifferentiated

Sugarberry 

Red maple 

Water oak 

Possumhaw 

American 

hornbeam

Overcup oak 

Pumpkin ash 

Red maple 

Water hickory 

American elm 

Green ash 

Diamond-leaf oak 

Sweetbay

16

21

11

24

Recognition of the scarcity of information that 

might be used to evaluate potential resource problems on 

the river and flood plain prompted the Florida Defenders 

of the Environment to sponsor a symposium on the 

Apalachicola Drainage System in April 1976. The proceedings were published by the Florida Department of 

Natural Resources, Marine Research Laboratory 

(Livingston and Joyce, 1977). An aspect that was emphasized by the conference speakers, but was acknowlTable 3. Ten dominant species of invertebrates collected by 

otter trawl in Apalachicola Bay

[Modified from Livingston and others, 1976]

Common name Scientific name Percent

White shrimp .... Penaeus setiferus . .

Grass shrimp. .... Palaemonetes pugio

Blue crab. ...... Callinectes sapidus.

Pink shrimp ..... Penaeus duorarum .

Brief squid ...... Lolliguncula brevis.

Brown shrimp. . . . Penaeus aztecus. ......

Olive Nerite ..... Neritina reclivata......

Swimming crab . . . Portunus gibbesii. .....

Grass shrimp. .... Palaemonetes vulgaris. . .

Mud crab ....... Rhithropanopeus harrisii.

40.1

20.4

20.2

5.3

4.3

2.6 

1.5 

1.1 

0.8

.5

edged to be poorly defined, was the role of the seasonal 

flooding cycle in the transport of litter-fall debris from the 

flood plain to the river and, ultimately, to the bay. This 

aspect was selected as the focus of the Apalachicola River 

Quality Assessment.

The Apalachicola River Quality Assessment was designed to define the cause-and-effect relation between 

existing hydrologic fluctuations and the tree community 

that occupies the flood plain, the production and decomposition of the litter fall, and the effectiveness of litter-fall 

transport from the flood plain to the river and the bay. 

Only when these relations are defined and measured can 

a rational scientific evaluation of river modifications be 

determined.

Background

The Apalachicola River Quality Assessment is 

unique within the River Quality Assessment Program because it was not conceived or designed to address existing 

problems. The Apalachicola basin is largely undeveloped, 

and it provides an appropriate setting for study of natural 

processes that might be sensitive to future development. 

Many of the alternative plans of the U.S. Army Corps of 

Engineers (COE) to upgrade navigation have caused concern among inhabitants of the area and State regulatory 

agencies. There is considerable disagreement about what 

types of problems might arise from different management 

practices, as described in reports such as the draft COE 

Environmental Impact Statement (EIS) of the river modification effects (U.S. Army Corps of Engineers, 1976), the 

evaluation of management alternatives by the U.S. Fish 

and Wildlife Service (1979), and the Estuarine Sanctuary 

EIS (U.S. Department of Commerce and State of Florida, 

1979). These reports differ on the types of problems that 

might arise.

Nutrient and Detritus Transport in the Apalachicola River, Florida C7
Conceptual Design

A conceptual design of the relations among the program components was developed (Mattraw and Elder, 

1980). The design called for work in three broad areas: 

flood-plain dynamics, nutrient and detritus sources, and 

nutrient yield. The data-collection procedures employed in 

the flood-plain dynamics components have been described 

by Leitman and others (1983). Three of the techniques described in that paper those used to measure rainfall, discharge, and flood-plain velocity are directly applicable 

to an evaluation of nutrient and detritus transport.

Nutrient and detritus sources include, among others, 

the vegetation of the flood plain. The tree species distribution (Leitman and others, 1983), or, more correctly, the 

forest type distribution, is an essential component in 

evaluating nutrient and detritus sources. The techniques 

used in measuring the leaf production of the five forest 

types have been described by Elder and Cairns (1982). 

Decomposition rate studies were experiments conducted at 

field sites under a variety of conditions representative of 

river and flood-plain conditions. The result of these procedures is an estimate of the annual potential supply of nutrients and detritus derived from the litter fall.

The forest-litter material that is actually transported 

through the flood plain and the river is measured as part 

of the third broad area, nutrient yield. The extent of inundation and flood-plain velocities during flooding are believed to be the major controls on the fraction of the potential nutrient and detritus supply that is transported. The 

data needs include systematic collection of water-quality 

samples, discharge, and various size fractions of particulate organic matter (detritus). Several additional components dealing with lateral inflow (streams and ground 

water), atmospheric input, and upstream watersheds are 

incorporated in the program design.

Apalachicola basin were made using Chattahoochee, 

Blountstown, Wewahitchka, and Sumatra gage records; 

the yields represent their respective parts of the basin. A 

fifth main-stem gage, near Apalachicola, Fla. (fig. 1), is 

strongly affected by tides and has not been rated with sufficient precision to permit discharge computations.

Determinations of water balance and nutrient transport depend on data from discharge gaging stations that 

can account for flow in the main stem and in tributaries. 

The main-stem gages separate the basin into three subbasins, as shown in figure 5. With the addition of boundaries representing the drainage area of each main-stem 

river gage, areas are defined for the subbasins. The subbasins are named according to their downstream order. The 

upper subbasin, 963 km2 in area, is between the gages at 

Chattahoochee and Blountstown. The middle subbasin, 

593 km2 in area, is between the Blountstown and 

Wewahitchka gages. The lower subbasin, 476 km2 in 

area, is between the Wewahitchka and Sumatra gages. 

The Chipola River basin is actually a 3,100-squarekilometer subbasin of the Apalachicola River basin. For 

this report, the Chipola subbasin ends where the Chipola 

River joins the Chipola Cutoff. The part of the 

Apalachicola River basin south of the Brickyard transect 

was excluded because diel tidal fluctuations made discharge calculations very difficult.

Table 5 summarizes the data-collection procedures 

used to determine nutrient and detrius yield. Included are 

the frequency of collection and recent references that detail the procedure. As indicated in table 5, the techniques 

for measuring flood-plain detritus, suspended detritus, and 

bottom-load detritus are unreferenced. These procedures 

were devised especially for the flow conditions of the 

large and swift Apalachicola River and its extensive flood 

plain.

APPROACH AND METHODS 

Subbasin Approach

Four main-stem stage-discharge gages provided data 

that could be used to calculate nutient loads to the headwaters of the Apalachicola River below Jim Woodruff 

Dam and to three points downstream (fig. 1). Thus it was 

possible to calculate water and nutrient balance for three 

subreaches of the river and for the system as a whole. 

This capability lent itself to an attempt to quantify the 

proportion of total loads derived from the flood plain.

Table 4 gives the location, station identification 

number, drainage area, organization responsible for 

maintenance, period of record, and average discharge for 

the 1979 water year for each gage on the Apalachicola 

River system. The calculations of nutrient yields for the

Intensive Data-Collection Transect Approach

Two intensive data-collection transects were established to gather detailed information on litter-fall production, leaf decomposition, and water-level fluctuation on 

the flood plain. The Sweetwater transect (fig. 6) runs perpendicular to the flood-plain corridor and crosses the 

Apalachicola River 14 km upstream of the Blountstown 

gage (navigation mile 87). Seven major data-gathering 

plots (fig. 6) were established to estimate litter fall (Elder 

and Cairns, 1982) for this upper river transect.

A second intensive data-collection transect representative of lower river conditions was established near 

Brickyard Landing (fig. 7). The Brickyard transect crosses 

the Apalachicola River 1 km downstream of the Sumatra 

gage (navigation mile 20). Clearly visible in figure 7 is 

the powerline right-of-way that lies parallel and 150 m 

north of the Brickyard transect. Nine major data-gathering

C8 Apalachicola River Quality Assessment
Table 4. Stage-discharge gage stations on the Apalachicola River, Florida

[Maintenance responsibility: USGS, U.S. Geological Survey; NWS, National Weather Service; COE, Corps of Engineers]

Station name and 

identification number

Apalachicola River at Chattahoochee, 

C235800.

Little Sweetwater Creek near Bristol, 

C2358685.

Apalachicola River near Blountstown,

02358700.

Apalachicola River near Wewahitchka,

02358754.

Chipola River at Dead Lake Outlet 

near Wewahitchka, 02359101.

Apalachicola River near Sumatra,

02359170.

Apalachicola River near Apalachicola, 

02359230.

Drainage 

area, in 

square 

kilometers

44,600

6.35 

45,600

46,100

3,100 

49,800

50,600

Maintenance 

responsibility

USGS

USGS

NWS

COE 

COE

USGS 

COE

USGS

USGS

Period of record

October 1928 through September 1980.

June 1979 through September 

1980.

January 1920 through September

1957 (stage only).

October 1957 through September 

1980.

October 1955 through September

1957 (stage only).

October 1965 through September 

1980.

November 1979 through September 1980.

May 1950 through September

1959; April 1965 through April 

1966 (stage and miscellaneous 

discharge measurements).

September 1977 through September 1980.

July 1978 through September 

1980.

Average 

discharge, 

in cubic 

meters per 

second

640

Not determined.

702

728

Not determined.

833

Not determined.

plots were established in this transect to estimate monthly 

litter-fall production and to measure flood-plain flow and 

detritus during flooding.

Data from the two intensive transects and eight 

cruise transects were determined to be adequate to support 

semiquantitative estimates of the productivity of the entire 

basin. The approaches, judgments, and statistical analyses 

of this sampling design were discussed in earlier reports 

(Elder and Cairns, 1982; Leitman and others, 1983).

Discharge Approach

Discharge at the main-stem gaging stations represents contributions from the entire subbasin. The reference 

flood elevation chosen by Leitman and others (1983) was 

that of a 2-year, 1-day flood. The extent of inundation by 

such a flood correlates closely with the distribution of bottom-land hardwood forest types. During 1980, the peak

discharge at Blountstown occurred on April 2. Its discharge, 3,100 m3/s, has a recurrence interval of approximately 4 years.

Water-Quality Sampling Approach 

Sample Location and Frequency

Water-quality samples for analysis of nutrients and 

suspended sediments were collected at each of the major 

gaging stations at least monthly between February 1979 

and June 1980. Samples were collected more frequently 

during the major flooding period in March and April 

1980. Because concurrent sampling was not possible, the 

different sampling sites had different sample intervals. 

Sample collection dates for each location are listed in 

table 6.

Nutrient and Detritus Transport in the Apalachicola River, Florida C9
C~ -V §§ORG1A__ __

ii^N / FLORIDA ""

EXPLANATION

A GAGING STATION 

 -SUBBASIN BOUNDARY

Figure 5. Apalachicola River subbasin components and gaging locations.

C10 Apalachicola River Quality Assessment
Table 5. Data-collection procedures used in determining nutrient and detritus transport

Procedure Number or frequency 

of collection

Reference

River flow

Stage recorder.

Tagline measurement

Moving boat

Flood-plain flow

Price current meter

1 5 minute or hourly punched tape, graphic recorders

(continuous). 

Each total flow measurement during flood (channels

in flood plain). 

Each flood flow measurement of main channel.

Used to measure all flow velocities except movingboat measurements.

Buchanan and Somers, 1968. 

Buchanan and Somers, 1969. 

Smoot and Novak, 1969.

Buchanan and Somers, 1969.

Ground water 

Recorder ...........

Tape down. .........

Water quality 

Collection ..........

Composite ..........

Silver filter. .........

0.45 Aim filter. .......

Preservation .........

Shipping ...........

Laboratory analysis . . . .

Detritus 

Pumped. ...........

Bottom load. ........

Flood-plain net .......

Plastic sheets ........

Hourly punched tape. 

Periodic.

Monthly, flood sampling. 

Each sample. 

Each sample for suspended organic carbon. 

Each sample for dissolved constituents (solids, 

nutrients). 

Iced. 

Within 1 day of collection. 

Within 2 days of receipt.

Monthly. 

Monthly. 

Flood sampling. 

Project period.

Buchanan and Somers, 1968. 

Brakensiek and others, 1979.

Brown and others, 1970. 

Guy and Norman, 1970. 

Beetem and others, 1980. 

Do.

Do. 

Do. 

Do.

Additional nutrient samples were collected at three 

other sites, off the main stem. One site was the Brickyard 

transect (fig. 7), where a composite sample was taken 

from Brickyard Cutoff, Brothers River, and when flooded, 

several points across the flood plain. To reach this area, 

water had to traverse a broad expanse of the flood plain 

and was, therefore, indicative of flood-plain outflow. 

Sampling on the Brickyard transect was done on the same 

days as at the Sumatra station (table 6).

A second off-channel site was at the mouth of the 

Chipola River at Dead Lake outlet (fig. 3). It was sampled 

on the same dates as the Wewahitchka station (table 6), 

except that it was not sampled during the period March 

13-April 28, 1980, because Apalachicola flooding produced reverse-flow at the site. The third off-channel site was 

at Little Sweetwater Creek (fig. 6), a small ground-waterfed stream 10 km north of Blountstown. Its water chemistry (low pH, specific conductance, and nutrient content) 

was very different from that of Apalachicola River water 

but was similar to that of other ground-water outlets in the 

basin; hence, it was considered representative of groundwater input. This site was sampled on the same dates as 

the Blountstown station (table 6) except during the 1980 

spring flood, when it was subject to backwater flood flow.

Sample Handling

A schematic diagram of the sample handling procedure is shown in figure 8. A point-integrating cable-andreel sampler, US P-61 (Guy and Norman, 1970), was 

used to obtain 10 or more depth-integrated water-quality 

samples across the channel width or the flood plain. Each 

sample was emptied into a large polycarbonate mixing 

container (churn). When sampling was complete, the 

cross-sectional composite sample was mixed and total nutrient and total residue samples were drawn into 1-L 

polypropylene bottles. Additional samples from the churn 

were pumped through a 0.45-|A membrane filter by a 

peristaltic pump. The filtered samples were stored in 500- 

mL polypropylene bottles. All samples were placed in icefilled coolers and shipped to the analytical laboratory.

Nutrient and Detritus Transport in the Apalachicola River, Florida C11
EXPLANATIO

Qr Sampling plot 

ATContinual - record 

£... surface water 

?-; ^ 1JF* gaging station

Observation well

Continual-record 

observation well

Figure 6. Locations of litter-fall sampling plots and water-level observation sites near the Sweetwater transect.

C12 Apalachicola River Quality Assessment
Brickyard 

Landing

EXPLANATION

D Sampling, plot

A--'. Continual record 

surface-water 

gaging Station

^ Observation weN

Continual record

observation well

Figure 7. Locations of litter-fall sampling plots, water-level observation sites, and rainfall gage near the 

Brickyard transect.

Nutrient and Detritus Transport in the Apalachicnla River, Florida C13
Table 6. Water-quality sample collection dates at the major river-gaging stations 

[Parentheses indicate dates when sampling was done for NASQAN program]

Month

1979

March ........

April. ........

May .........

June .........

July .........

August .......

September .....

October. ......

November .....

December .....

1980 

January .......

February ......

March ........

April. ........

May .........

June .........

Chattahoochee

27

(6), 14, (19)

3, (10), 24

16, (21)

18

23, (31)

20, (28)

(18), 26

(25)

(14), 19

18

21, (28)

26

9, 10, 18, (23), 26

2,23

(15), 21

(16), 25

Blountstown

28

14

3,24

16

18

23

20

26

25

19

18

22

27

10 (twice), 12, 18, 26

2,23

20

25

Wewahitchka

28

15

4,25

17

19

24

22

27

24

20

17

22

27

11, 13, 19, 27

3,28

20

24

Sumatra

1, 16

5, 11,26

17

19

24

21

27

2,24

20

17

23,28

28

4, 11, 13, 14, 19, 27

3, 28

19

24

Samples for carbon analysis were placed in a 100- 

mL stainless-steel pressure filter apparatus with a 0.45-(ji 

silver filter. Both filtered and unfiltered samples for carbon analyses were collected in 60mL, oven-fired (500°C) 

glass bottles having aluminum foil cap liners. The 0.45-(ji 

silver filter containing the suspended material was folded 

and placed in a petri dish for shipment.

The water-quality constituents analyzed and the general method of analysis are presented in table 7. Analytical results not presented in this report are published in 

"Water-Resources Data for Florida, Volume 4, Northwest 

Florida" (U.S. Geological Survey, 1979, 1980, 1981) and 

can also be accessed through WATSTORE (U.S. Geological Survey computerized water data storage and retrieval 

system) with the station identification numbers listed in 

table 4.

Bulk Precipitation Approach and Method

Bulk precipitation is the solution that results when 

rainfall incorporates the products of dry fallout 

(Whitehead and Feth, 1964). Four bulk precipitation collectors (fig. 9) were used in the Apalachicola basin near

the main-river sampling sites. Samples were retrieved 

from the collectors monthly, coinciding with river sampling. It is recognized that the relatively simple design of 

the collectors did not minimize the various possible 

sources of error described by Galloway and Likens 

(1976). It was not practical for this study to collect dry 

and wet deposition separately or to retrieve samples at 

daily or weekly intervals. Some potential problems were 

mitigated, however, by the environmental conditions. Deposition of fine dry materials and various gases, for example, was not likely to contribute significantly to atmospheric input in this relatively humid area. Many chemical 

transformations that might have taken place between sample collections were of little consequence because the 

samples were analyzed for total organic carbon, nitrogen, 

and phosphorus only.

Atmospheric loading of nutrients to the subbasins 

for the period June 19, 1979, to June 25, 1980, was calculated using analytical data and National Weather Service 

rainfall records at the locations indicated in figure 10. 

Rainfall records for two locations were average for each 

subbasin to obtain a distributed rainfall depth across each 

subbasin. Records of rainfall near Sumatra were not available, so a recording rain gage was installed at the Brickyard transect to provide the desired rainfall coverage.

C14 Apalachicola River Quality Assessment
SAMPLER

FILTERED 

DISSOLVED"

CARBON

UNFILTERED 

"TOTAL"

NITROGEN

AND 

PHOSPHORUS

ANALYTICAL 

LAB

Figure 8. Water-quality sample handling procedures.

Ground-Water Component

The ground-water contribution to the Apalachicola 

River was estimated during the design phases of the 

Apalachicola River Quality Assessment to be less than 5 

percent of the dry weather total flow (Mattraw and Elder, 

1980). This estimate was based on records of discharge 

increases between Chattahoochee and Blountstown during 

low flow. Regional water-level mapping (fig. 11) of the 

principal artesian aquifer (Floridan aquifer) indicated that 

the steepest ground-water gradient toward the 

Apalachicola River is between these two main-stem gage 

locations. Low-flow discharge records and the groundwater gradient led to the establishment of several wells for 

observation of ground-water elevations in the Sweetwater 

transect (fig. 6). In addition, a surface-water gage was established on nearby Little Sweetwater Creek to observe its

flow, which was principally ground-water discharge. The 

creek's drainage basin is 6.4 km2 . Calculations of groundwater-contributed load are based on low-flow water-quality samples from Little Sweetwater Creek that were processed like main-stem water-quality samples.

Between Chattahoochee and Blountstown, the regional pattern of ground-water contours for the Floridan 

aquifer (fig. 11) is north and south, parallel to the 

Apalachicola basin. Farther down river, the ground-water 

contour direction is more nearly east and west. This indicates that the ground-water contribution in the southern 

half of the river is much less and is more difficult to 

measure without an extensive system of water-table monitoring wells. Since the gain in information would have 

had such a small effect on the overall estimates of nutrient 

transport in the river system, only a few wells were installed in the lower river basin for qualitative comparisons of 

river levels with ground-water levels.

Detritus Methods 

Suspended Detritus

Several particle-size classifications of detritus (particulate organic matter) are currently in use. The most common recognizes three major size ranges: coarse, fine, and 

very fine (Naiman and Sedell, 1979). Coarse paniculate organic matter (CPOM) is defined as organic particles greater 

than 1 mm across. For this study, particles greater than 63 

JJL (0.063 mm) but smaller than 1 mm were classified as fine 

paniculate organic matter (FPOM). Particles smaller than 63 

JJL but greater than 0.45 |x were classified as very fine particulate organic matter (VFPOM).

CPOM and FPOM were collected on 1-mm and 63- 

|x nested sieves attached to the side of the sampling boat. 

Water was pumped from depths of 0.5, 1.5, and 3.0 m for 

10 minutes each as the boat slowly traversed the river 

cross section. The pumping rate was 10 L a minute, which 

produced a detritus sample representing 300 L of river 

water. The samples were rinsed from the sieves into 

labeled mason jars. The samples were shipped to the laboratory, where they were oven dried at 105°C and weighed, 

then ashed at 500°C and weighed again. The weight of organic matter was determined by subtracting the ash weight 

from the dry weight. Organic matter weights were converted to organic carbon weights by multiplying by 0.5, 

a conversion factor arrived at by chemical analysis of detrital material from the flood plain (Elder and Cairns, 

1982).

VFPOM data were obtained from analysis of the 

0.45-|x silver filter that was used to filter the dissolved organic carbon sample. The particulate matter captured on 

the silver filter was termed "suspended organic carbon" 

(SOC). This SOC sample included fine and very fine parNutrient and Detritus Transport in the Apalachicola River, Florida C15
Table 7. Analytical techniques used in the determination of chemical and physical characteristics of water samples

Parameter Analytical technique 1

Total organic carbon .... 

Dissolved organic carbon. . 

Suspended organic carbon. 

Total inorganic carbon . . . 

Dissolved inorganic carbon

Total organic nitrogen . . . 

Dissolved nitrate, nitrite . . 

Dissolved ammonia ..... 

Dissolved organic nitrogen. 

Dissolved orthophosphate.

Dissolved phosphorus....

Total phosphorus ......

Chloride ............

Dissolved solids. .......

Total solids ..........

Temperature. .....

pH ............

Specific conductance 

Dissolved oxygen. . .

Combustion, infrared absorption by carbon dioxide. 

Do. 

Do. 

Do. 

Do.

Colorimetric, block digester-salicylate. 

Colorimetric, cadmium reduction-diazotization. 

Colorimetric, indophenol. 

Colorimetric, Kjeldahl. 

Colorimetric, phosphomolybdate.

Colorimetric, phosphomolybdate.

Do.

Colorimetric, ferric thiocyanate. 

Residue on ignition at 105 C.

Do.

Thermometer, on site. 

Water-quality monitor, on site.

Do.

Do.

1 References for organic carbon, Goerlitz and Brown, 1972; for all analyses except organic carbon, Skougstad and others, 1979.

tides; coarse material was excluded because of the narrow 

opening on the sampler nozzle. Hence, the carbon concentration of VFPOM was determined by subtracting FPOM 

as carbon from SOC.

Bottom-Load Detritus

CPOM includes all sizes greater than 1 mm. Coarse 

material transported along the river bottom could not be 

sampled by the pump-sampling apparatus; yet, it was 

judged to be too important to be overlooked. Early experimentation led to a stationary net dredge (fig. 12) designed to sample coarse bottom-load particles that are 

transported along the bed of the river hence the term 

"bottom-load" paniculate organic carbon (BPOC). The 

stainless-steel frame of the net dredge has an 860-mm by 

240-mm opening which holds a 1.5-m-long, 1-mm-mesh 

nylon net. Four kg of lead weight attached to the bottom 

edge of the frame hold the bottom leading edge flush with 

the river bed when the boat is anchored in place. The net 

is lowered to the bottom by a mounted crane and is left 

in place for 20 minutes. The velocity of the water entering 

the net is measured with an attached flow meter. The volume of water for the bottom-load sample is calculated 

from the cross-sectional area of the net opening, the velocity of the water, and the time the net is in place.

Several cross-sectional profiles of bottom-load organic carbon were made under different discharge conditions. In all cases, samples from the mid-20 percent of the 

channel accounted for close to 50 percent of the total 

BPOC (fig. 13). The monthly, or more frequent, bottomload samples were all collected at midchannel, and all estimates of BPOC were based on the assumption that 50 

percent of the material was outside of the sampled section. 

The collected organic material was hand picked from the 

detachable net and placed in pressure-closure plastic bags. 

The samples were shipped to the laboratory for oven-dry 

and ash weights, in the same manner as the other organic 

carbon size fractions.

Flood-Plain Detritus

Net collection. The large quantity of litter fall 

resting on the flood-plain floor is in various stages of decomposition when seasonal flooding begins. Because only a part 

of the litter fall is transported, a method for estimating the 

fraction transported during flooding was devised. Figure 14 

shows a device developed for sampling detritus moving 

through the flood plain. Samples were collected during 

flooding at numerous points in each of the two intensive 

transects. The device was placed well away from stream 

channels, but care was taken to avoid areas of dense vegetation where detritus would be trapped.

C16 Apalachicola River Quality Assessment
Figure 9. Bulk precipitation apparatus used for collection 

of total carbon, total nitrogen, and total phosphorus 

samples.

The flood-plain detritus net (fig. 14) has an opening 

300 mm wide by 1.7m high. The net is 2 m long and tapers to a 300-mm-diameter opening at the rear. A coarse 

mesh outer net is used to support an inner 1-mm-mesh 

collection net. The double net is closed at the trailing end 

with a drawstring. The side bars of the net are constructed 

of 10-mm threaded steel rod approximately 2 m long. The 

side bar rods extend about 150 mm below the bottom net 

support. For detritus collection, these extension rods were 

driven into the flood-plain floor by stepping on the bottom 

net support or when the water was over 1 m deep, by 

driving the rods from the top with a hammer. Nylon cord 

attached to the threaded rods above the top net support 

was attached to nearby trees to achieve a vertical position. 

The net was flushed of any debris accumulated during 

emplacement and the drawstring was pulled. The depth of 

water in the net opening, the time, and the current velocity were recorded.

The net was left in place for 2 to 24 hours, depending on accessibility and water velocity. The depth, time, 

and current velocity were recorded when the net was recovered. The depth and velocity used to calculate the volume of water passing through the net were the averages 

of the beginning and ending depths and velocities.

The entrained material was rinsed to the back of the 

net, the drawstring was opened, and the material was 

emptied into marked pressure-closure plastic bags. Like 

the other detritus samples, this material was shipped to the 

laboratory for oven-dry and ash weights.

Plastic-sheet collection. The flood-plain detritus 

net was used to estimate the proportion of the litter fall 

that was transported under the conditions at the time the 

sample was collected. The suspended and bottom-load detritus data collected in the main river channel were designed to estimate the fraction that was captured by the 

river and ultimately was transported to Apalachicola Bay. 

All of these techniques were relatively short term; collections were made over periods of 20 minutes to 24 hours.

A method used to supplement short-term detritus 

data was a long-term collection technique intended to provide an independent measure of the amount of material in 

transport but remaining on the flood plain after flooding. 

The collection material was a 1-square-meter plastic sheet 

held flush to the ground with eight large nails around the 

perimeter. Three plastic sheets were installed at randomly 

selected locations in each of the 16 intensive-plot locations. The sheets were installed in early September 1979. 

In late December 1979, the litter fall resting on the sheets 

was sprayed with fluorescent orange paint. After the 

March-April flood had receded, 31 sheets were recovered. 

Seventeen sheets were not recovered because they were 

lost, destroyed, folded, or in some other manner invalidated.

In the laboratory, the presence or absence of 

fluorescent orange leaves was noted. The sample was 

weighed, and a subsample was separated into coarse and 

fine fractions with a 1-mm sieve. These fractions were 

dried, and their oven-dry ash weights were determined.

Data Handling

Surface-water-quality and stage-discharge records 

are routinely collected, prepared, and then stored in the 

WATSTORE computer file (Hutchinson, 1975). A 

generalized representation of the major steps between the 

collection of data and the nutrient and detritus load results 

presented in this report is shown in figure 15. All waterquality analyses and stage-discharge records are published 

annually and are also accessible through NAWDEX (Edwards, 1977).

The temporary data file labeled ARQA QW (fig. 

15) represents the water-quality analytical results which

Nutrient and Detritus Transport in the Apalachicola River, Florida C17
85°30' 85°I5' 85°00' 84°45' 84°30'

3 I °00'

30°45' -

30°30' -

EXPLANATION

Apclcchicola River

basin boundary 

Drainage divide for

gaging stations 

National Weather

Service rain gage

location 

USGS rain gage

location 

Bulk precipitation

gage

OF MEXICO

30°I5' -

30° 00' 5

29° 45' -

Figure 10. Locations of National Weather Service and U.S. Geological Survey rain gages and bulk 

precipitation sample collectors in the Apalachicola basin, Florida.

C18 Apalachicola River Quality Assessment
POTENTIOMETRIC 

SURFACE, IN 

METERS ABOVE 

SEA LEVEL

Figure 11. The potentiometric surface of the Floridan aquifer in May 1976.

Nutrient and Detritus Transport in the Apalachicola River, Florida C19
Figure 12. Sampling apparatus used for collection of bottom-load particulate organic material.

were set aside primarily for computation of the water 

budget and transport of nutrients and detritus. The computer program to calculate transport, ARQA LOAD (fig. 

15), accessed the water-quality analytical results and the 

average daily discharge (ARQA DV).

In an earlier study of hydraulic and nutrient 

budgets, Scheider and others (1978) reported on the relative accuracies of various possible methods for determining nutrient input. The best model resulted from the combination of discrete stream nutrient concentration data with 

continuous discharge data. Since continuous nutrient concentration data are virtually impossible to obtain, the best 

estimate for an interval is obtained by using the concentration at the midpoint of the interval. The product of integrated discharge from continuous records and the discrete 

midpoint nutrient concentration thus gives the best estimate of transport.

The ARQA LOAD program was written to calculate 

the midpoint date between any two sets of samples. Each 

water-quality data point represented the sample interval 

beginning at the midpoint date between the previous and 

current samples and ending at the midpoint date between

the current and subsequent samples. The sample interval 

thus defined was used to calculate the mean sample interval discharge, using mean daily discharges computed from 

continuous streamflow record. Transport for the sample 

intervals is reported as metric tons of the particular constituent. The transport per day is reported only for the particular day the sample was collected and is reported as 

metric tons per day.

The time period chosen to represent annual transport 

(metric tons per year) was June 3, 1979, through June 2, 

1980, a period of 366 days. This 1-year span includes a 

complete spring flood (March-May 1980) as well as some 

low flows and brief high-water peaks that characteristically occur at other times of the year. It also represents a 

period during which water-quality and detritus sampling 

was thorough. Although sampling began in February 

1979, methods were in the process of refinement during 

the early months of the program. The period selected to 

represent annual transport also nearly coincides with the 

September 1979 to September 1980 sample collecting 

period for litter-fall measurements (Elder and Cairns, 

1982).

C20 Apalachicola River Quality Assessment
iJU

uj 40

isi °-

< z

^< 30

o z

CD DC

PERCENTAGE OF

ORGANIC C/r

m n H

ro_ 

go o

i i

-

-

_

i i

i

i i

BE 0.9 0.7 0.5 0.3

OF WATER

-

-

.

-

O.I Rl

\\J\J 

80 5

O

I

DC.

Ul 

Q.

60 w

DC. 

O

Z

40 i-r 

oc. 

o

CL 

CO

Z

IT

H

20

0 

GHT EDGE

OF WATER

FRACTION OF WIDTH OF RIVER CROSS SECTION 

NEAR SUMATRA

Figure 13. Results of cross-sectional sampling on July 2, 

1979.

RESULTS

Because of the movement of water through the 

river-wetland system, physical transport of nutrients to 

Apalachicola Bay is possible. The computation of nutrient 

transport (weight) requires the collection of discharge data 

(volume) and concentration data (weight/volume). All data 

were separated by date into time periods that correspond 

to different hydrologic conditions during the study year. 

Subsequently, discharge data, combined with other water 

input and output information, were used to determine a 

water budget, and nutrient and detritus concentration data 

were computed on both a seasonal and an annual basis. 

Estimates of the magnitude and significance of error in 

these computations were included.

Seven Hydrologic Periods

As previously described, the annual budgets were 

calculated for a full year beginning June 3, 1979, and ending June 2, 1980. The year was subdivided into seven 

periods, according to hydrologic changes. The periods 

also varied a great deal in the rate of forest litter fall on 

the flood plain, which has important effects on nutrient 

and detritus transport. The seven periods may be characterized as follows:

1. Summer (June 3-September 8; 98 days) Continuous 

low flow was interrupted only slightly by a minor peak 

in July; the peak was below flood stage. Litter fall was 

moderate. Tupelo, the most common tree in the flood 

plain, began to shed leaves in July.

2. Early autumn (September 9-October 13; 35 days) 

Heavy rainstorms in the basin produced unseasonally 

high flows, especially in the lower river basin. After the 

storm, the flows rapidly decreased to a low level. Some 

flooding occurred in the lower flood plain. Litter fall increased substantially.

3. Late autumn (October 14-January 4; 83 days) A moderate increase in flow in November-December caused 

some shallow flooding in the lower flood plain in December. Litter fall from most tree species was voluminous and reached maximum levels in November (Elder 

and Cairns, 1982).

4. Winter (January 5-March 8; 64 days) Flow remained 

at a moderate level, producing continuous shallow 

flooding in the lower flood plain. Litter fall decreased 

considerably, but some species, particularly the oaks, 

planer-tree, and sweetgum, continued to shed leaves 

during the winter months.

5. Spring flood rise (March 9-March 16; 8 days) An abrupt increase in flow produced extensive flooding over 

the entire length of the river basin. Discharge increased 

threefold in 8 days. Litter fall decreased to low levels.

6. Spring flood peaks (March 17-April 20; 35 days) 

High flow was continuous, well above flood stage in the 

entire basin. Three flood peaks occurred, with 

maximum flow in early April of 3,850 m3/s at Sumatra. 

New leaves appeared on trees and litter fall remained 

low.

7. Spring flood recession (April 21-June 2; 43 days) The 

recession of the river flow was interrupted by a secondary peak of 1,900 m3/s in late May. Litter fall increased slightly.

These periods were selected to represent different 

hydrologic events and were not delimited by climatic conditions, fiscal periods, or arbitrary dates. Consequently, 

their lengths vary considerably. Most of them are considerably longer than 1 month, minimizing errors associated 

with calculations over short time spans (Winter, 1981). 

The spring flood rise period is necessarily short to represent the rising limb of the flood. During a short period 

with high flows, only the discharge component of the 

water budget is significant. Discharge estimates based on 

stage-discharge relations at the continuous-recording gages 

are the most accurate of all water-budget components.

Nutrient and Detritus Transport in the Apalachicola River, Florida C21
Figure 14. Flood-plain detritus net used to measure transported forest litter.

Therefore, an 8-day period to represent the spring flood 

rise is acceptable.

Water Budget

An equation that expresses the water budget of the 

Apalachicola River system is:

WO= WI+ Pro + Pdp + GW+CR- Ret ± r, (1)

where all terms represent volumes of water and are defined 

as follows:

WO equals outflow at the downstream limit;

WIequals inflow at the upstream limit;

Pro equals precipitation runoff;

Pdp equals direct precipitation in river and flood plain;

GWequals ground-water discharge;

CR equals input from mouth of Chipola River;

Ret equals evapotranspiration of river-derived water; and 

r equals residual the amount required to balance the equation (equivalent to an error term and not associated with any 

known component of the budget).

The equation may be applied to each subbasin or to the 

entire basin upstream of the Sumatra gage. Application of 

the equation is dependent on accurate estimates of budget 

components for each subbasin and each period. The 

methods and data used are described in the following sections.

The water budget described by equation 1 is depicted diagrammatically in figure 16. Numbers shown 

with each component are overall estimates for the 1979-80 

study year; their derivations and seasonal breakdowns are 

detailed in subsequent tables and text. Several of the 

major components, shown by large circles, can be subdivided into more specific categories. Only the components or subcomponents that provide direct input to or outflow from the river-wetland system are included in equation 1.

C22 Apalachicola River Quality Assessment
Figure 14. Flood-plain detritus net used to measure transported forest litter Continued.

Figure 15. Major steps in data collection and handling. (See 

text for explanation of symbols.)

Precipitation (P) in the basin is separated into four 

categories:

Pgw equals precipitation-derived water that enters the 

ground-water system before it has any contact with.the 

river or the flood plain. Percolation through the soil 

may alter its chemistry considerably.

Pro equals precipitation that enters the river or flood plain 

as surface runoff. Any nutrient and detritus contribution made by the upland communities is likely to be 

transported by this route. 

Pdp equals direct precipitation in the river channels and

flood plain.

Pet equals precipitation in the uplands that re-enters the atmosphere by evapotranspiration without ever reaching 

the river-wetland system.

Since these are the only subdivisions of the precipitation component, it follows that:

 Pgw + Pro + Pdp + Pet (la)

Similarly, evapotranspiration (ET) is composed of 

water from two sources: water from precipitation, just defined under the term Pet , and water lost to the atmosphere 

from the river and wetland, termed Ret.

ET=Pet +Ret. db)

Ground water (GW) is also broken down into two 

fractions, one that comes from inside the basin, originating as precipitation (Pgw), and another that comes from 

outside the basin, (GW0). Ground-water flow can be 

bidirectional; hence, both GW and GW0 can be either 

positive or negative.

dc)

Nutrient and Detritus Transport in the Apalachicola River, Florida C23
PV=Q n A:, K2 , (2)

where

BASIN BOUNDARY

Figure 16. Representation of Apalachicola water budget. 

(See text for explanation of symbols; values are in cubic 

kilometers.)

Streamflow

Each subbasin was delimited at its upstream and 

downstream ends by a continuous-recording stage recorder. Stage-discharge relations have been established for 

each of these sites on the basis of ratings drawn from current-meter measurements. Total period volume was calculated for each site from the daily discharge data, using the 

equation

PV equals period volume, or flow of water, in km3 ;

Q equals mean daily discharge during the period, in ft3/s;

n equals number of days in the period;

KI equals number of seconds per day (8.64 X 104); and

K2 equals number of km3 per ft3 (2.83 x 10"'').

The results of these calculations are shown in table 8. At 

each site, PV becomes WO for the upstream subbasin and 

WI for the downstream subbasin.

Precipitation

The total precipitation for each subbasin was based 

on National Weather Service data from nearby rain gages 

(fig. 10). Values of P were calculated for each subbasin, 

and for the entire Apalachicola basin, by the equation

(3)

where

Ru equals rainfall at upstream site, in inches; 

Rd equals rainfall at downstream site, in inches; 

A equals total area of subbasin, in km2 ; 

Ar3 equals kilometer per inch (2.54 X 10"5).

The computations produced the precipitation estimates 

shown in table 9.

Once the total rainfall in the basin was known, the 

values of direct precipitation (Pdp) could be computed

Table 8. Flow volumes by gaging sites and the seven periods 

[Volumes are in cubic kilometers]

Period

Gaging site

Dates

Chattahoochee Blountstown Wewahitchka Sumatra

Summer. . ..............

Early autumn .............

Winter. .................

Spring flood rise ...........

Spring flood peak ..........

Spring flood recession .......

Total for year ...........

. . . . . 06/03/79-09/08/79

. . . . . 09/09/79-10/13/79

. . . . . 10/14/79-01/04/80

. . . . . 01/05/80-03/08/80

. . . . . 03/09/80-03/16/80

. . . . . 03/17/80-04/20/80

. . . . . 04/21/80-06/02/80

. . . . . 06/03/79-06/02/80

3.18

1.28

3.09

3.73

1.54

6.39

3.65

22.86

3.67

1.48

3.41

3.68

1.47

6.81

3.61

24.13

3.69

1.74

3.36

4.13

1.12

6.37

3.71

24.12

4.52

2.06

3.96

4.23

1.14

8.06

4.64

28.61

C24 Apalachicola River Quality Assessment
Table 9. Precipitation in the seven periods and the Apalachicola basins from June 3, 1979, through June 2, 1980

[Precipitation (P) in cubic kilometers]

Subbasin

Period Dates

Upper Middle

Total for year, 06/03/79-06/02/80 1.50 1.22

Lower

0.92

Entire basin

Summer. ..................

Early autumn ...............

Late autumn. ...............

Winter. ...................

Spring flood rise .............

Spring flood peak ............

Spring flood recession .........

...... 06/03/79-09/08/79

...... 09/09/79-10/13/79

...... 10/14/79-01/04/80

...... 01/05/80-03/08/80

...... 03/09/80-03/16/80

...... 03/17/80-04/20/80

...... 04/21/80-06/02/80

0.47

0.29

0.14

0.21

0.09

0.20

0.10

0.43

0.29

0.10

0.13

0.06

0.14

0.07

0.30

0.23

0.09

0.10

0.04

0.09

0.07

1.20

0.81

0.33

0.44

0.19

0.43

0.24

3.64

from the ratio of flood-plain area to total watershed area. 

Other subdivisions of precipitation were computed indirectly. Runoff (Pro) was determined from historical records of measurements of small tributary streams in the 

basin. Both Little Sweetwater Creek near Bristol and Flat 

Creek near Chattahoochee (fig. 10) have been measured 

on several occasions during both base low-flow and higher 

flow conditions. Base flows in these streams are attributable to ground-water discharge; hence, the difference between mean annual flow and base flow gives an estimate 

of the amount contributed by runoff. This may be converted to an annual volume per unit watershed area and 

extrapolated to the entire basin.

The term Pet, or the amount of precipitation lost by 

way of evapotranspiration in the uplands, is computed as 

part of the overall evapotranspiration estimate, to be described subsequently. Once Pet is known, along with 

P(JP and Pro , the fraction involved in ground-water recharge (Pgw) can be determined by difference.

Ground Water

Ground-water discharge occurs as springs in the river 

and along the west bank, as seeps along the steep east bank, 

and as streamflow in various small tributaries. Discharge 

seeps are quite common above Blountstown, where the 

limestones of the Floridan aquifer approach land surface, becoming exposed at various points in the river channel and on 

bluffs near the east bank. From there, the top of the aquifer 

dips to the south until it is about 46 m below sea level at 

Apalachicola (Kwader and Schmidt, 1978). The Chipola 

River rises on Floridan limestones near Dothan, Ala., flows 

through Dead Lake, and joins the Apalachicola River near 

Wewahitchka some 90 km south. Much of the flow of the 

Chipola River is derived from ground-water discharge.

Regional water-level mapping (fig. 11) of the 

principal artesian (Floridan) aquifer indicates the existence

of steep gradients to the Apalachicola and Chipola Rivers 

in their upper reaches, and flat gradients normal to them 

in the south. This is consistent with Kwader and 

Schmidt's (1978) "Top of Floridan Aquifer" map and area 

of known ground-water discharge. Pascale and Wagner 

(1982), in their investigation of the water resources of the 

Ochlockonee River basin, explained the high and steep 

water levels on the east side of the Apalachicola River. 

They found recharge to the Floridan to be limited by 

overlying clay beds and by the aquifer's low permeability 

and transmissivity.

Estimates of ground-water discharge can be derived 

from various data taken from flow measurments. A series 

of low-flow measurements on the main channel of the 

Apalachicola River at Chattahoochee and Blountstown 

provides the most reliable data from which to estimate 

ground-water discharge. Between 1957 and 1980, U.S. 

Geological Survey personnel made 16 same-day 

measurements of the two sites during low-flow periods. 

The mean discharge increase for the 16 measurements was 

20 m3/s, or 0.6 km3/yr. This was attributed to groundwater inflow, because there was no significant 

contribution from overland runoff or surface-water 

tributaries.

Flow measurements also were made on small 

streams that empty into the Apalachicola River in the 

upper subbasin. During dry periods, these streams are 

almost exclusively sustained by ground-water discharge. 

Total ground-water discharge of 0.4 km3/yr was estimated 

by calculating mean discharge per unit watershed area on 

the basis of low-flow measurements (table 10) of three 

streams in the upper subbasin. Since this estimate does not 

account for seepage, spring flow, or ground-water 

discharge to the river during other than low-flow periods, 

it is assumed to be low. It is therefore quite consistent 

with the estimate of 0.6 km3/yr derived from the river 

low-flow measurements.

Nutrient and Detritus Transport in the Apalachicola River, Florida C25
Table 10. Mean discharge per unit watershed area based on low-flow measurements 

[Q = low-flow discharge;/! = watershed area]

Mosquito Creek, September 23, 1976

Q= 1.28m3 Is A =223 km2

I.28m3 /s _ 

223 km2 = 0.0057 (m3 /s)/km2

Flat Creek, October 18, 1976

= 0.54m3 /s A =64.5 km2

Q.54m3 /s_ 

64.5 km2 = 0.0084 (m 3 /'s}/km2

Little Sweetwater Creek, September 16, 1980

!2 = 0.116m3 /s A =6.35 km2 

Q '\\6mJS = 0.0183 (m3 /s)/km2

A verage for three streams

0.0057 + 0.0084 + 0.0183

= 0.0108(w3 /s)A;m'

Chattahoochee to Blountstown annual ground-water discharge

A = 963 km2

1 km' 0.0108 (m3 /s)lkm2 X ^hjX 3.1536 X 107^L-X 963 ^m2 = 0.33 km3 /year 

v 7 10 m year

The middle and lower subbasins presumably show 

much less ground-water discharge to the river because the 

water-level gradient shifts toward a direction nearly 

parallel to the river flow (fig. 11). In fact, some additional 

flow measurements from the lower subbasin indicate that 

ground-water discharge is negligible in that region. The 

annual water-budget estimates are therefore as follows:

Subbasin

Upper . 

Middle . 

Lower .

Annual groundwater discharge, 

in km3

0.6

0.1

0

Seasonal fractions of these annual ground-water 

discharge volumes are determined as the amounts

proportional to the time fraction involved. This assumes a 

constant ground-water flow rate, an assumption made 

because of insufficient data. A more likely relation is that 

ground-water discharge decreases during initial phases of 

a flood, then increases during the flood recession. Data 

are not available, however, to document such a pattern in 

the Apalachicola system.

Table 10 values represent estimates for the term 

GW in equation 1. The fraction that results from recharge 

within the basin (Pgw) was already determined from precipitation data. The remaining fraction (GW0) the 

amount of discharge to or recharge from the ground-water 

system ouside the basin can be determined by difference.

Chipola River Inflow

The Chipola River is the only major tributary to the 

Apalachicola. Flowing south from Alabama, it forms

C26 Apalachicola River Quality Assessment
Dead Lake, then enters the Apalachicola near 

Wewahitchka. With a mean annual flow of 100 m3/s, the 

Chipola River is a major surface-water input to the lower 

subbasin. Like some of the small streams in the upper part 

of the Apalachicola basin, the Chipola is spring fed at its 

source near Dothan, Ala.

The inflow from the Chipola River, which becomes 

the CR component in the water budget equation when applied to the lower subbasin or to the entire basin, is shown 

in table 11. The upper and middle subbasins obviously 

have no CR component.

Table 11. Inflow from Chipola River at Dead Lake, June 3, 

1979, through June 2, 1980

Period

Summer. ...........

Early autumn ........

Late autumn. ........

Winter. ............

Spring flood rise ......

Spring flood peaks .....

Spring flood recession . .

Total for year ......

of

days

98

35

83

64

8

35

43

366

Mean flow

(in cubic

meters

per second)

68

151

62

80

178

244

125

103

Total flow

(in cubic

kilometers)

0.58

0.46

0.44

0.44

0.14

0.74

0.46

3.26

Evapotranspi ration

No data from direct monitoring of evaporation or 

solar radiation were available. Estimates of evaporation 

could be made, however, on the basis of ambient temperature and estimated water-retention factors of the soil.

The method of calculation of potential evapotranspiration, as described by Thornthwaite and Mather (1957), 

is based on the equation

ET= 1.6(10777)' (4)

where

FT equals monthly potential evapotranspiration, in mm; 

T equals mean monthly temperature, in degrees Celsius; 

/equals heat index = (775) 1 514 ; and 

a equals exponent related to the annual heat index, /, by 

the expression

a=(6.75x 10- 7/3 )-(7.71 x lQ-5/2 ) + 0.01797-0.49. (5)

The unadjusted potential evapotranspiration rate resulting 

from the application of equation 4 is then corrected for

month and day length. The result is the maximum potential evapotranspiration that would be expected at the given 

temperatures, with high soil-water retention.

In the Apalachicola basin, the wetland area may be 

expected to have higher ET rates than the uplands. This 

is because of the high soil moisture in large areas that remain permanently saturated or flooded. Water loss from 

cypress flood-plain forests has been demonstrated to be 

nearly equal to standard pan evaporation rates (Brown, 

1981). The uplands are characterized by mostly sandy 

soils. Using as estimated 250-mm water-retention factor 

for sandy soils (Thornthwaite and Mather, 1957), the 

overall ET rate in the uplands was estimated to be 0.8 of 

the maximum potential ET. The final computation of 

monthly ET for a basin or subbasin then becomes

ET=(ETmax x Aw} + (0.8 ETmax x Au\ (6)

where

ET equals water loss due to ET, in km3 ; 

ETmax equals maximum potential ET, in km3 ; 

Aw equals area of wetland, in km2 ; and 

Au equals area of upland, in km2 .

The two terms on the right side of equation 6 represent the 

two previously described components of evapotranspiration (fig. 16), Ret andPel, respectively.

Annual ET rates and estimates of ET for the three 

subbasins are given in table 12. The ET rates are somewhat higher than the annual rate of 1,016 mm (40 inches) 

estimated by Qureshi (1978) for the Apalachicola basin. 

Summer ET rates, however, are very similar to those determined by Brown (1981) for cypress flood-plain forests, 

using measurements in polyethylene chambers. Monthly 

ET varies over an order of magnitude, from 16 mm in 

February to more than 160 mm in July.

Table 12. Estimates of annual evapotranspiration (ET) in 

Apalachicola subbasins, June 3, 1979, through June 2, 

1980

Area (km 2 )

Subbasin

Upper .....

Middle. ....

Lower. ....

Upland

885

429

325

Flood 

plain

78

164

151

Mean 

annual

temperature 

in °C

20.0

19.9

19.7

Evapotranspiration

Maxiannual 

rate,

millimeters

1,060

1,050

1,040

Estimated 

volume, 

in cubic

kilometers

0.85

0.54

0.44

Nutrient and Detritus Transport in the Apalachicola River, Florida C27
Overall Water Budget basins and within some periods. In particular, there is an

	apparent reversal of this trend during the spring flood rise.

The quantities calculated for each of the budget This may be attributed to lag time in the flood wave (2

components and presented in tables 8, 9, 11, and 12 are to 3 days from Chattahoochee to Sumatra) which becomes

combined in equation 1, to produce tables 13-16. Water significant in a short period when flow increases rapidly,

inflow (WI) is the dominant contributor to each of the Because of this lag, the rising limb of the flood did not

subbasins. The Chipola River adds a substantial volume of actually begin at Sumatra until March 11. Thus, the spring

water in the lower subbasin. The ground-water contribu- flood rise included 2 days of relatively low flow at

tion in the upper subbasin is significant, especially during Sumatra.

low-flow periods (summer, late autumn, winter). Precipi- Other cases in which the data showed a decrease in

tation and evapotranspiration involve a sizable volume of flow downstream were the winter, spring flood rise, and

water in the basin, but much of that is confined to the up- spring flood recession periods in the upper subbasin and

land hydrologic cycle (fig. 16). Their roles in the river- the late autumn, spring flood rise, and spring flood peaks

wetland water budget, although significant, are small in periods in the middle subbasin. Although some or all of

comparison with streamflow. these reversals may be real, they all may be due to error,

The data show a general increase in flow from up- since they are within error limits (see later error analysis),

stream to downstream sites, the increase between Chat- One factor that may contribute to error, particularly in the

tahoochee and Sumatra being 5.75 km3/yr, or 20 percent middle subbasin (table 4), is the existence of side channels

of the total flow at Sumatra. Exceptions occur within sub- in the vicinity of the Wewahitchka gage. Such channels

Table 13. Water budget in the upper subbasin (Chattahoochee-Blountstown), by periods, June 3, 1979, through

June 2, 1980

[All values in cubic kilometers. See text for beginning and ending dates of periods and expalantion of abbreviations]

Period

Summer. ...........

Early autumn ........

Winter. ............

Spring flood recession . .

Total for year. . . . . .

Number 

of days

98

35

83

64

8

35

43

366

WO

3.67 =

1.48 =

3.41 =

3.68 =

1.47 =

6.81 =

3.61 =

24.13 =

WI +

3.18 4

1.28 4

3.09 4

3.73 4

1.54 4

6.39 4

3.65 4

22.86 4

pro +

- 0.09 4-

0.06 4-

- 0.03 4-

- 0.04 4-

0.02 4-

- 0.04 4-

- 0.02 4-

- 0.30 4-

'*

0.04

0.02

0.01

0.02

0.01

0.02

0.01

0.13

± GW

+ 0.16

+ 0.06

4- 0.14

4- 0.10

4- 0.01

4- 0.06

4- 0.07

4- 0.60

- Ret *

- 0.04 +

- 0.01

- 0.01 +

- 0.005 -

- 0.001 -

- 0.005 4-

- 0.01

4- 0.08 4-

r

0.24

0.07

0.15

0.21

0.11

0.31

0.13

0.16

Table 14. Water budget in the middle subbasin (Blountstown-Wewahitchka), by periods, June 3, 1979, through

June 2, 1980

[All values in cubic kilometers. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ...........

Early autumn ........

Winter. ............

Spring flood recession . .

Total for year. .....

Number 

of days

98

35

83

64

8

35

43

366

WO

3.69 =

1.74 =

3.36 =

4.13 =

1.12 =

6.37 =

3.71 =

24.12 =

WI 4

3.67 4

1.48 4

3.41 4

3.68 4

1.47 4

6.81 4

3.61 4

24.13 4

' pro +

- 0.07 4-

- 0.05 4-

- 0.02 4-

0.02 4-

- 0.01 4-

0.02 4-

0.01 4-

0.20 4-

" dP

0.12

0.08

0.03

0.03

0.02

0.04

0.02

0.34

± GW

+ 0.03 -

4- 0.01

+ 0.02 ~

4- 0.02 -

4- 0.00 -

4- 0.01

4- 0.01

4- 0.10 -

* *

0.08 -

0.02 4-

0.02

0.01 4-

0.003 -

0.01

0.03 4-

0.17 -

r

0.12

0.14

0.10

0.39

0.38

0.50

0.09

0.48

C28 Apalachicola River Quality Assessment
Table 15. Water budget in the lower subbasin (Wewahitchka-Sumatra), by periods, June 3,1979, through

June 2,1980

[All values in cubic kilometers. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ...........

Early autumn ........

Late autumn. ........

Winter. ............

Spring flood rise ......

Spring flood peaks. . . . .

Spring flood recession . .

Number 

of days

98

35

83

64

8

35

43

366

WO

4.52 =

2.06 =

3.96 =

4.23 =

1.14 =

8.06 =

4.64 =

28.61 =

Wl H

3.69 H

1.74 H

3.36 H

4.13 H

1.12 H

6.37 H

3.71 H

24.12 H

- pro +

h 0.03 +

h 0.03 +

h 0.01 +

h 0.01 +

h 0.004 +

h 0.01 +

h 0.01 +

h 0.10 +

p dp

0.10

0.07

0.03

0.03

0.01

0.03

0.02

0.29

± CR

+ 0.58

+ 0.46 -

+ 0.44 -

+ 0.44 -

+ 0.14 -

+ 0.74 -

+ 0.46

+ 3.26

Ret ±

0.08 +

0.02 -

0.02 +

0.01

0.002 -

0.01 +

0.02 +

0.16 +

r

0.20

0.22

0.14

0.37

0.13

0.92

0.46

1.00

Table 16. Water budget in the Apalachicola basin (Chattahoochee-Sumatra), by periods, June 3, 1979, through

June 2, 1980

[ All values in cubic kilometers. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ...........

Early autumn ........

Late autumn. ........

Winter. ............

Spring flood rise ......

Spring flood peaks. ....

Spring flood recession . .

Total for year. .....

Number 

of days

98

35

83

64

8

35

43

366

WO

4.52

2.06

3.96

4.23

1.14

8.06

4.64

28.61

H

= 3

= 1

= 3

= 1

= 6

= 3

= 22,

VI

.18 -

.28 -

.09 -

.73 -

.54 -

.65 -

.86 -

+ Pro +

 f 0.19 +

 f 0.14 +

 f 0.06 +

 f 0.07 +

f 0.03 +

f 0.07 +

f 0.04 +

4- 0.60 +

rdp H

0.26 -

0.17 -

0.07 -

0.08 -

0.04 -

0.09 -

0.05 -

0.76 -

h GW ±

h 0.19 -

h 0.07 -

h 0.16 -

h 0.12 -

h 0.01 i

h 0.07 -

h 0.08 -

h 0.70 H

CR -

\- 0.58 -

h 0.46 -

h 0.44 -

h 0.44 -

h 0.14 -

h 0.74 -

h 0.46 -

h 3.26 -

Ret

0.20

0.05

0.05

0.02

0.01

0.02

0.06

0.41

+

+

+

 .

+

+

+

r

0 39

001

0 19

0 19

061

07?

0.42

0,84

may divert water out of the channel for short distances, to 

re-enter at points downstream. These diversions may 

"hide" some flow from the measurement section and produce low-flow results.

Nutrient Concentrations 

Nutrient Concentrations in the River

The principal elements of interest in the analysis of 

nutrient flow were organic carbon, inorganic and organic 

nitrogen, and phosphorus. Nutrients can vary as a function 

of time, discharge, and location. Both particulate and dissolved phases were collected routinely in riverine samples.

Figure 17 illustrates the mean concentration and 

standard error for total organic carbon, total nitrogen, and 

total phosphorus at the four main river water-quality collection stations. Variations in concentration with respect to

location were small. The only statistically significant difference (analysis of variance) was in total organic carbon 

between Chattahooch.ee and Blountstown. The large increase in carbon concentrations in the upper subbasin 

probably resulted from high carbon production in the 

flood plain and high flood velocities that caused significant transport from the flood plain to the river. The relatively small temporal changes in nutrient concentrations 

are shown by the standard error. Temporal variations were 

generally random, with no clear pattern of change with 

season. Unlike some constituents (Daniel and others, 

1979), nutrient concentrations were not closely correlated 

with discharge.

Bulk-Precipitation Concentrations

Bulk precipitation includes dry fallout and rainfall. 

Concentrations of total organic carbon, nitrogen, and

Nutrient and Detritus Transport in the Apalachicola River, Florida C29
10

8 -

UJ

o

I °

£ 0.10

UJ

h- 0.08

Z

-I 0.06

Z

Z 0.04

0.02

0

TOTAL ORGANIC 

CARBON

TOTAL NITROGEN

TOTAL PHOSPHORUS

EXPLANATION 

MEAN CONCENTRATION 

AND STANDARD ERROR 

FOR SITES INDICATED

Figure 17. Mean nutrient concentrations for the period 

February 1979 through July 1980 at the four main river 

collection stations with standard error bars.

phosphorus in bulk precipitation showed variability over a 

considerable concentration range. The data were plotted 

on probability paper (fig. 18) using the method of Velz 

(1970, p. 522-542). Abrupt slope changes indicated that 

the frequency distribution of sample concentrations was 

skewed, probably owing to contamination of some of the 

samples. Calculations of loads based on means from the 

complete data base would result in unreliable bulk precipitation estimates. A better estimate was provided by the 

median value for each nutrient for all periods and subbasins. The median values are: total organic carbon, 5 mg/L; 

total nitrogen, 0.6 mg/L; and total phosphorus, 0.06 mg/ 

L.

Ground-Water Chemistry

Ground-water inflow is a relatively minor part of 

total water flow in the basin (table 13-16), and its imporF

I "T

0

aoi

0.9

TOTAL 

CARBON

001 0 I "I

,.T

30 SO 70

TOTAL 

NITROGEN

01 1.0 10 30 50 70 90

TOTAL 

PHOSPHORUS

01 1.0 10 30 50 70 90

PROBABILITY

99 99.9 99.99

Figure 18. Total carbon, total nitrogen, and total phosphorus concentrations in bulk precipitation samples.

C30 Apalachicola River Quality Assessment
tance as a nutrient source is small. Ground water was 

found discharging from seeps in the upper reaches of Flat 

Creek and Little Sweetwater Creek (fig. 10). Water analysis (table 17) of Little Sweetwater Creek suggest that its 

residence time in the ground was rather short. The low 

levels of chloride, dissolved solids, pH, and conductance 

are similar to those of other seeps and springs in northern 

Florida (Rosenau, Faulkner, Hendry, and Hull, 1977). 

Water analyses of Flat Creek indicate slightly higher concentrations of dissolved solids, conductance, and phosphorus. These analyses tend to indicate water movement 

through the phosphate-rich limestones of the Hawthorn 

Formation, which crops out in this drainage basin.

Chipola River

Concentrations of most elements were nearly the 

same in Chipola River water (Dead Lake Outlet) as in 

Apalachicola River water (table 17). Total phosphorus 

was the exception, with 0.02 mg/L in Chipola water compared with 0.05 mg/L in Apalachicola water. The Chipola 

River is the only large tributary to the Apalachicola River, 

and, with nutrient concentrations comparable to those of 

the Apalachicola, its contribution to streamflow and the 

transport of nutrients in the Apalachicola system is appreciable.

Nutrient Transport

The two basic types of data described previously 

discharge and nutrient concentration provide the elements necessary to compute nutrient transport. The term 

"transport," as used here, is defined as the mass of material that moves past a given point in a given time span. 

Other terms, such as "flux," "load," and "flow," often are 

used in similar context. The term "yield" refers to total 

annual transport per unit area.

Total organic carbon (dissolved carbon plus suspended organic carbon) concentrations for Sumatra are 

shown in figure 19. Each sample concentration represents 

an interval of time of 1 to 34 days. The mean sample interval discharge, in cubic meters per second (m3/s), is 

shown below the total organic concentration. Above the 

mean discharge are the seven periods used previously in 

the water budget summaries.

Transport was calculated for each sample interval. 

The sample interval volume (IV), computed as the mean 

of daily discharge during the sample interval (equation 2), 

was multiplied by the corresponding sample concentration 

(O to obtain nutrient transport (Y) for the sample interval

y=(/V)(C). (7)

Table 17. Mean nutrient concentrations and chemical characteristics of ground water compared with water of the 

Apalachicola River near Blountstown and the Chipola River near Wewahitchka

[Concentrations of first eight constituents in milligrams per liter. N = number of samples; std. dev. = standard deviation]

Ground water Surface water

Constituent

Total organic carbon ...........

Dissolved organic carbon. ........

Total nitrogen. ...............

Dissolved nitrogen .............

Total phosphorus .............

Dissolved phosphorus. ..........

Chloride ...................

Total dissolved solids ...........

Flat Creek near 

Chattahoochee

/V

...... 4

...... 8

...... 3

...... 9

...... 1

...... 6

...... 6

mean

4.8

0.82 

.13 

.21 

.15 

3.6 

34

std. 

dev.

1.7

0.18 

.16 

.15

1.0 

7.6

Little Sweetwater 

Creek

/V

16 

13 

16 

12 

16 

16 

11 

15

mean

5.5 

4.9 

0.31 

.23 

.01 

.01 

1.9 

18

std. 

dev.

3.6 

3.5 

0.19 

.15 

.01 

.01 

.5 

6

Apalachicola River 

near Blountstown

/V

23 

19

23 

22 

23 

23 

22 

10

mean

7.4 

6.7 

0.77 

.62 

.05 

.02 

3.9 

60

std. 

dev.

3.7 

3.7 

0.26 

.18 

.02 

.01 

.5 

8

Chipola River 

near Wewahitchka

/V

17 

8 

17 

13 

17 

18 

18 

1?

mean

8.6 

7.9 

0.74 

.63 

.02 

.01 

4.5 

86

std. 

dev.

4.5 

4.4 

0.20 

.17 

.01 

.01 

.4 

7

Characteristic (range): 

pH ........................... 12 5.3-7.5

Conductance (micromhos per centimeter). . 12 35 46

16 4.6-6.8 22 5.7-7.8 16 6.3-7.6

16 10-20 23 57-127 18 80-180

Nutrient and Detritus Transport in the Apalachicola River, Florida C31
o

&L 5'

s

(/)

i

Figure 19. Total organic carbon concen charge, andseven hydrologic periods a

a

t/5

c £ 

3 o

W 3

 H "* 

W "

' 3 

o>

T3_ 

0)

5' 

f?

I

o.

DISCHARGE, IN CUBIC METERS PER SECOND

979

CD 

00 

O

TOTAL ORGANIC CARBON (DOC+SOC) 

IN MILLIGRAMS PER LITE

O

o
Transport for each of the seven periods was then calculated as the sum of the sample interval transports within 

the period. Annual transport was the sum of the seven 

transport periods. The annual transport at Sumatra was defined as the yield for the basin.

Nutrient transport in the Apalachicola River system 

may be expressed by an equation analogous to that used 

to describe the water budget:

Y0 =Y,.+ Ydp +Ym +Ygw +Ycr ± Yfp ±Yr, (8)

where

Y equals general symbol for transport of nutrient C, N, or

P-,

Y0 equals outflowing nutrient transport at downstream

limit;

Yj equals inflowing nutrient transport at upstream limit; 

Ydp equals nutrient input by bulk precipitation in the river

and flood plain;

Yro equals nutrient runoff from upland areas; 

Ygw equals nutrient input by ground-water discharge; 

Ycr equals nutrient input by inflow of the Chipola River; 

Yfp equals net nutrient release or uptake by the flood-plain

ecosystem; and 

Yr equals residual (includes error and other components

such as atmospheric diffusion and anthropogenic

sources, all judged to be of minor importance).

Nutrient Transport Residual

The Yfp term may be either positive or negative, depending on whether the flood-plain ecosystem acts as a 

source or a sink for nutrients. This term could be subclassified according to various nutrient-consuming or nutrientrelease processes, such as nitrogen and carbon fixation, 

cenitrification, and sorption. The important quantity for 

the nutrient-transport calculations, however, is the overall 

uptake or release of the nutrient, hence the net flood-plain 

term, Yfp .

The wetland, or flood plain, is the foremost example of a unit within which both uptake and release processes operate. Litter-fall data gathered as part of the present 

study (Elder and Cairns, 1982) documents the large quantity of nutritive material deposited each year on the floodplain floor. This is a potential source of 180,000 metric 

tons of carbon annually. Presumably, a large fraction of 

this material is retained in the flood-plain soils; however, 

much remains to be transported to the river and eventually 

to the estuary. Quantification of the recycled and floodplain-derived transported fractions was not possible by direct measurement, but transport of material in the flood 

plain during high-water periods was observed. Detritus 

movement in the flood plain was documented by use of 

stationary drift nets, described earlier.

Because there were no direct measurements of Yfp, 

it must be estimated by including it as part of the Yr term. 

A new term, ±R, is thus created to replace the terms 

± Yfp and ± Yr in equation 8. Because it includes the 

flood-plain term, which is potentially large, R is likely to 

have an absolute value considerably greater than the simple residual. The resulting equation is

dp Ycr ±R. (9)

Transport, 1979-80

The results of application of equation 9 to 1979-80 

data from the three Apalachicola subbasins and the entire 

basin are shown in tables 18-29. In most cases, nutrient 

transport increased in a downstream direction; that is, Yt 

tended to be smaller than Y0 , and R tended to be positive. 

Exceptions to this occurred quite frequently within single 

subbasins and periods, but as the scale is expanded either 

in space or time, exceptions become fewer. In certain 

periods and subbasins, negative R values appeared consistently for all three nutrients. Those include the winter in 

the upper subbasin, the late autumn in the middle subbasin, and the spring flood rise and spring flood recession 

in the lower subbasin. Of the 12 equations representing 

annual nutrient transport, only 2 had negative R values: 

carbon transport in the middle subbasin (table 19) and nitrogen transport in the lower subbasin (table 24).

The R term represents a major component in the 

overall nutrient budget because it includes the flood-plain 

contribution to nutrient input or uptake. Some large negative R values clearly suggest that there were periods of 

considerable nutrient retention in the flood plain. These 

periods were compensated by even greater nutrient release 

in other periods, however, and the annual basin budget 

showed positive flood-plain contributions of all three nutrients. As a fraction of the annual nonstreamflow nutrient 

inputs [R/(Yro + Ydp + Ygw + R)], the residual accounts for 

65 percent of the carbon, 16 percent of the nitrogen, and 

78 percent of the phosphorus.

Direct precipitation in the flood plain and runoff 

from upland areas produced significant inputs to the river 

during certain periods of the year. This was particularly 

true during the early autumn, when there was a great deal 

of local rainfall. Table 21 shows that carbon input from 

runoff (Cro ) accounted for more than 60 percent of the 

total nonstreamflow carbon input (Cm + Cdp + Cgw + R) in 

the early autumn period. Direct precipitation contributed 

an additional 30 percent of that amount during the same 

period. For the entire year, these precipitation-related inputs were of less significance for carbon and phosphorus, 

but still contributed over half of the nonstreamflow nitrogen input. Ground-water discharge contributed all three

Nutrient and Detritus Transport in the Apalachicola River, Florida C33
Table 18. Total carbon transport in the upper subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .............

Early autumn ..........

Late autumn. ..........

Winter. ..............

Spring flood rise .........

Spring flood peaks. ......

Spring flood recession . . . .

Total for year ........

1 At Blountstown. 

2 At Chattahoochee.

Number 

of days

98

35

83

64

8

35

43

366

C0 l

51,600

8,200

19,200

15,300

6,900

63,900

27,800

192,900

= ci

16,000

5,400

12,800

18,300

3,500

64,700

22,000

- 142,700

* c*

f 200 

f 100 

f 50 

f 100 -

f 50 -

f 100 

f 50 

f 650 

+ cro

4- 1,170

4- 780

f 390

f 520

f 260

+ 520

4- 260

4- 3,900

+ gw

+ 660

+ 250

+ 580

+ 410

+ 40

+ 250

+ 290

+ 2,480

± R

+ 33,570

+ 1,670

+ 5,380

4,030

+ 3,050

1,670

+ 5,200

+ 43,170

Table 19. Total carbon transport in the middle subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .............

Early autumn ..........

Late autumn. ..........

Winter. ..............

Spring flood rise ........

Spring flood peaks .......

Spring flood recession ....

Total for year ........

1 At Wewahitchka. 

2 At Blountstown.

Number 

of days

98

35

83

64

8

35

43

366

Co'

32,200

7,200

14,300

18,800

10,000

54,800

43,400

180,700

- c,.

51,600

8,200

19,200

15,300

6,900

63,900

27,800

= 192,900

+ C H dp

+ 600 4

+ 400 4

+ 150 4

+ 150 4

+ 100 4

+ 200 4

+ 100 4

+ 1,700 4

- Cro

910

650

260

260

130

260

130

- 2,600

f cgw

f- 120

h 40

h 80

I- 80

H 0

H 40

h 40

f- 400

* 

21,030

2,090

5,390

+ 3,010

+ 2,870

9,600

+ 15,330

16,900

Table 20. Total carbon transport in the lower subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ..............

Early autumn ...........

Late autumn. ...........

Winter. ...............

Spring flood rise .........

Spring flood peaks. .......

Spring flood recession .....

Total for year .........

1 At Sumatra. 

2 At Wewahitchka. 

3 At Dead Lake.

Number 

of days

98

35

83

64

8

35

43

366

Co'

40,100

12,100

17,300

3 1 ,000

8,700

73,500

31,100

213,800

= C- 2

32,200

7,200

14,300

18,800

10,000

54,800

43,400

= 180,700

+ C 4 dp

+ 500 4

+ 350 4

+ 150 4

+ 150 4

+ 50 4

+ 150 4

+ 100 4

+ 1,450 4

 cro

390

390

130

130

50

130

130

 1,350

+ V ±

+ 7,420 -

+ 3,830 +

+ 3,130 -

+ 2,760 +

+ 6,650 -

+ 5,140 +

+ 640 -

+ 29,570 +

R

410

330

410

9,160

8,050

13,280

13,170

730

C34 Apalachicola River Quality Assessment
Table 21. Total carbon transport in the Apalachicola basin between Chattahoochee and Sumatra, by periods, June 3,

1979, through June 2, 1980

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

[All figures rounded]

Period

Summer. ...........

Early autumn ........

Late autumn. ........

Winter. ............

Spring flood rise ......

Spring flood peaks. . . . .

Spring flood recession . .

Total for year ......

1 At Sumatra. 

2 At Chattahoochee.

Number 

of days

98

35

83

64

8

35

43

366

C l 

40,100 =

12,100 =

17,300 =

31,000 =

8,700 =

73,500 =

31,100 =

213,800 =

Cf <

16,000 H

5,400 H

12,800 H

18,300 H

3,500 H

64,700 H

22,000 H

142,700 H

> c* <

h 1,300 H

h 850 H

h 350 H

h 400 4

H 200 H

H 450 4

H 250 H

h 3,800 4

- cro H

- 2,470 H

- 1,820 H

780 H

910 H

440 H

910 H

520 H

- 7,850 H

- cgw +

780 4

290 4

660 +

490 +

40 +

290 +

330 +

- 2,880 +

ccr ±

7,420 +

3,830 -

3,130 -

2,760 +

6,650 -

5,140 +

640 +

29,570 +

R

12,130

90

420

8,140

2,130

2,010

7,360

27,000

Table 22. Total nitrogen transport in the upper subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .............

Early autumn ..........

Late autumn. ..........

Winter. ..............

Spring flood rise ........

Spring flood peaks. ......

Spring flood recession ....

Total for year ........

1 At Blountstown. 

2 At Chattahoochee.

Number 

of days

98

35

83

64

8

35

43

366

V

1,750

1,110

2,920

2,430

1,200

4,100

5,070

18,580

. Nf

2,320

820

2,030

3,580

830

4,280

4,000

= 17,860

+ "dp '

f 24

f 12

f 6

f 12

f 6

f 12

f 6

f 78

* Nro

f- 36

)- 24

)- 12

)- 16

1- 8

1- 16

1- 8

1- 120

"H yV Q W

+ 43

+ 16

+ 38

+ 27

+ 3

+ 16

+ 19

+ 162

± R

673

+ 238

+ 834

1,205

+ 353

224

+ 1,037

+ 360

Table 23. Total nitrogen transport in the middle subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .............

Early autumn ..........

Late autumn. ..........

Winter. ..............

Spring flood rise ........

Spring flood peaks. ......

Spring flood recession ....

Total for year ........

1 At Wewahitchka. 

2 At Blountstown.

Number 

of days

98

35

83

64

8

35

43

366

V

2,110

950

2,750

3,110

1,340

4,590

4,800

19,650

= Nf

1,750

1,110

2,920

2,430

1,200

4,100

5,070

= 18,580

+ "dp 4

+ 72 -\

+ 48 4

+ 18 4

+ 18 4

+ 12 4

+ 24 4

+ 12 4

+ 204 4

' Nro

28

20

8

8

4

8

4

80

+ /V

+ 8

+ 3

+ 5

+ 5

+ 0

+ 3

+ 3

+ 27

± R

+ 252

231

201

+ 649

+ 124

+ 455

289

+ 759

Nutrient and Detritus Transport in the Apalachicola River, Florida C35
Table 24. Total nitrogen transport in the lower subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .............

Early autumn ..........

Late autumn. ..........

Winter. ..............

Spring flood rise ........

Spring flood peaks .......

Spring flood recession ....

Total for year ........

1 At Sumatra. 

2 At Wewahitchka. 

3 At Dead Lake.

Number 

of days

98

35

83

64

8

35

43

366

V

3,340

1,520

2,730

3,630

920

5,670

3,670

21,480

- Hf

2,110

950

2,750

3,110

1,340

4,590

4,800

= 19,650

+ Ndp 4

+ 60 -\

+ 42 -I

+ 18 4

+ 18 4

+ 64

+ 18 4

+ 12 4

+ 174 4

- Nro

12

12

4

4

4

4

42

+ Ncr 3 ±

+ 343 +

+ 233 +

+ 398

+ 372 +

+ 472

+ 527 +

+ 215

+ 2,560

R

815

283

440

126

900

531

1,361

946

Table 25. Total nitrogen transport in the Apalachicola basin between Chattahoochee and Sumatra, by periods, June 3,

1979, through June 2, 1980

[AH equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ...........

Early autumn ........

Winter. ............

Spring flood rise ......

Spring flood peaks. . . . .

Spring flood recession . .

Total for year ......

1 At Sumatra. 

2 At Chattahoochee.

Number 

of days

98

35

83

64

8

35

43

366

v -

3,340 =

1,520 =

2,730 =

3,630 =

920 =

5,670 =

3,670 =

21,480 =

Nj2 H

2,320 H

820 H

2,030 H

3,580 H

830 H

4,280 H

4,000 H

17,860 H

h Ndp H

h 156 -

H 102 -

h 42 H

h 48 H

h 24 H

h 54 H

h 30 H

h 456 H

> Nro "

I- 76 4

h 56 4

h 24 4

h 28 H

h 14 -\

H 28 -\

h 16 4

h 242 -\

- *w 

51 -

19 -

43 -

32 -

3 -

19 -

22

- 189 -

* Ncr +-

t- 343 +

f 233 +

f 398 +

f 372

t- 472 -

f 527 +

f 215 -

t- 2,560 +

R

394

290

193

430

423

762

613

173

Table 26. Total phosphorus transport in the upper subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. ..................

Early autumn ...............

Late autumn. ...............

Winter. ...................

Spring flood rise .............

Spring flood peaks. ...........

Spring flood recession .........

Total for year .............

1 At Blountstown. 

2 At Chattahoochee.

Number 

of days

..... 98

. . . . . 35

..... 83

..... 64

. . . . . 8

..... 35

..... 43

..... 366

V =

122 =

69

179

159

106

497

247

1,379

ff +

123 +

56 +

147 +

226 +

82 +

485 +

221 +

1,340 +

pdp

2.4

1.2

0.6

1.2

0.6

1.2

0.6

7.8

+ gw

+ 1.8

+ 0.7

+ 1.5

+ 1.1

+ 0.1

+ 0.7

+ 0.8

+ 6.7

± R

5.2

+ 11.1

+ 29.9

69.3

+ 23.3

+ 10.1

+ 24.6

+ 24.5

C36 Apalachicola River Quality Assessment
Table 27. Total phosphorus transport in the middle subbasin, by periods, June 3, 1979, through June 2, 1980 

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Period

Summer. .......................

Early autumn ....................

Eate autumn. ....................

Winter. ........................

Spring flood rise ..................

Spring flood peaks. ................

Spring flood recession ..............

Total for year ..................

1 At Wewahitchka. 

2 At Blountstown.

Table 28. Total phosphorus transport in 

[All equation values in metric tons. See text

Period

Summer. .......................

Early autumn ....................

Eate autumn. ....................

Winter. ........................

Spring flood rise ..................

Spring flood peaks. ................

Spring flood recession ..............

Total for year ..................

Number l 

of days °

98 165 

35 98 

83 164 

64 204 

8 101 

35 505 

43 300

366 1,537

'/ +

122 + 

69 + 

179 + 

159 + 

106 + 

497 + 

247 +

1,379 +

'dp +

7.2 + 

4.8 + 

1.8 + 

1.8 + 

1.2 + 

2.4 + 

1.2 +

20.4 +

gw ±

0.3 + 

0.1 + 

0.2 

0.2 + 

0.0 

0.1 + 

0.1 +

1.0 +

R

35.5 

24.1 

17.0 

43.0 

6.2 

5.5 

51.7

136.6

the lower subbasin, by periods, June 3, 1979, through June 2, 1980 

for beginning and ending dates of periods and explanation of abbreviations]

Number j 

of days °

98 164 

35 89 

83 189 

64 284 

8 76 

35 604 

43 246

366 1,652

pl +

165 + 

98 + 

164 + 

204 + 

101 + 

505 + 

300 +

1,537 +

PdP +

6.0 + 

4.2 + 

1.8 + 

1.8 + 

0.6 + 

1.8 + 

1.2 +

17.4 +

P 3 +

cr

10 

13 

11 + 

8 + 

11 

18 + 

4 _

75 +

1 At Sumatra. 

2 At Wewahitchka. 

3 At Dead Lake.

Table 29. Total phosphorus transport in the Apalachicola basin between Chattahoochee and Sumatra, by periods 

June 3, 1979, through June 2, 1980

[All equation values in metric tons. See text for beginning and ending dates of periods and explanation of abbreviations]

Number Period ^ ^ / of days

Summer. ................ 98

Early autumn ............. 35

Eate autumn. ............. 83

Winter. ................. 64

Spring flood rise ........... 8

Spring flood peaks. ......... 35

Spring flood recession ....... 43

Total for year ........... 366 1,

V = »>

164 = 123 

89 - 56 

189 = 147 

284 = 226 

76 - 82 

604 = 485 

246 = 221

652 = 1,340

* v *

+ 15.6 + 

+ 10.2 + 

+ 4.2 + 

+ 4.8 + 

+ 2.4 + 

+ 5.4 + 

+ 3.0 +

+ 45.6 +

gw +

2.1 + 

0.8 + 

1.8 + 

1.3 + 

0.1 + 

0.8 + 

0.9 +

7.8 +

Pcr ±

10 + 

13 + 

11 + 

8 + 

11 

18 + 

4 +

75 +

R

17.0 

26.2 

12.2 

70.2 

36.6 

79.2 

59.2

22.6

>

R

13.3 

9.0 

25.0 

43.9 

19.5 

94.8 

17.1

183.6

'At Sumatra.

2 At Chattahoochee.

Nutrient and Detritus Transport in the Apalachicola River, Florida C37
nutrients in amounts somewhat less than the amounts 

originating from direct precipitation.

Detritus

Concentrations

Mean concentrations of coarse (>1 mm), fine 

(0.063-1 mm), and very fine (<0.063 mm) paniculate organic carbon are shown in figure 20. Data from the four 

major gaging sites and six hydrologic periods are included 

(early and late autumn data were combined because relatively few measurements were obtained during these two 

periods).

Concentrations of coarse paniculate organic carbon 

(CPOC) ranged from none detectable at Chattahoochee to 

0.07 mg/L during the three spring flood periods at 

Sumatra. CPOC samples obtained at Chattahoochee were 

consistently less than 0.01 mg/L. A general trend of 

downstream increase in CPOC mean concentration was 

observed throughout all periods. The mean concentrations 

at Blountstown, Wewahitchka, and Sumatra were at least 

50 percent higher during the three spring flood periods 

than during the other periods.

Fine particulate organic carbon (FPOC) concentrations generally increased from Chattahoochee to 

Wewahitchka and decreased slightly from Wewahitchka to 

Sumatra. Averaged over the full year, FPOC concentrations were approximately 12 times greater than CPOC 

concentrations.

Concentrations of very fine particulate organic carbon (VFPOC) increased slightly from Chattahoochee 

down river, with little change from Blountstown to 

Sumatra. Averaged over the full year, VFPOC concentrations were approximately 3.4 times greater than FPOC. 

Concentrations during the three spring flood periods averaged 1.0 mg/L, while the mean concentration during the 

other periods was approximately 0.7 mg/L.

A fourth detritus fraction measured with a stationary, 1-mm net dredge was bottom particulate organic carbon (BPOC). Figure 21 shows the period concentrations 

for the four main river sampling locations. The capture of 

BPOC below Jim Woodruff Dam near Chattahoochee was 

less than 0.01 mg/L, except during the spring flood rise. 

Detectable, but relatively low, concentrations were measured downstream at Blountstown. During most of the 

year, BPOC concentrations near Wewahitchka were intermediate to those at Blountstown and Sumatra. BPOC 

mean concentrations were consistently highest for all 

periods at Sumatra; concentrations in summer were low 

(0.1 mg/L) and increased twelvefold during the autumn. 

Concentrations increased even more during the winter and 

spring flood rise at Sumatra, but decreased during the 

flood peaks. With the return of flood waters from the

flood plain to the main channel during the spring flood recession, BPOC concentrations at Wewahitchka and 

Sumatra reached their highest levels of the year. High 

BPOC concentrations during the flood rise may have been 

due to initial removal of material deposited on or near the 

river bank, whereas the high concentrations during the recession were more likely the result of rapid drainage from 

the interior of the flood-plain forest.

Transport

The particulate organic carbon fraction, known as 

detritus, is a relatively small part of the total organic carbon transport shown in tables 18-21. The transport of detrital materials may be further examined by particle-size 

categories. Detritus transport measurements (fig. 22) 

showed that there were substantial gains of large-particle 

detritus (CPOC and BPOC, both having particle sizes 

greater than 1 mm) from Chattahoochee to Sumatra. The 

coarse fractions made up only a small part of total carbon 

but showed more than sixtyfold gains from Chattahoochee 

to Sumatra. The fine particulate fraction (0.063-1.0 mm) 

also increased, showing a threefold to fourfold gain from 

Chattahoochee to Wewahitchka and Sumatra. Consistent 

increase with downstream distance was not exhibited by 

the very fine particulate fraction. Since VFPOC was the 

dominant carbon fraction, its downstream changes were 

closely reflected by the total suspended carbon, and only 

a slight increase was observed at Sumatra.

The relation between detritus transport and time is 

shown in table 30. The suspended fraction transport rates 

were generally higher during the three spring flood 

periods than during earlier, drier periods. Bottom-load 

POC transport rates increased from summer to winter, 

then showed only a slight increase during the spring flood 

rise and recession periods.

Flood-Plain Transport

The transport of detritus in the flood plain during 

flooding was verified by trapping transported material in 

stationary nets, as described previously. Between March 

11 and April 28, 1980, 21 flood-plain detritus collections 

were made in nets randomly located near the intensive 

plots. All nets collected measurable amounts of detritus, 

generally about two-thirds organic. The amounts varied 

greatly, from 0.001 to 0.5 g of material per cubic meter 

of water. The mean of the 21 samples was 0.05 g/m3 , 

with a standard deviation of 0.10 g/m3 . Data for the individual collections are given in "Supplementary Data I."

Deposition on Flood-Plain Floor

Estimates of the amount of material deposited in the 

flood plain were obtained from thirty-one 1-square-meter

C38 Apalachicola River Quality Assessment
MEAN PARTICULATE ORGANIC CARBON, IN MILLIGRAMS 

orid

gure 20

e organ

bon concen

Summe

Early andLate 

Autumn

Winte

SPR 

Rise

G FPeaks

OOD 

Recession

°

"

~

o 

°

o

°
(E 

UJ

UJ

a.

CO

o 

o

z

o 

a: 

o

UJ

ID 

O

O 

GO

Z 

UJ

3.5

- 2.5

z 

o

CD

or

2.0

1-5

1.0

0.5

0

EXPLANATION

C Ch.attahoochee

B Blountstown

W Wewahitchka

S Sumatra

W

W

B

B

W

B

c W B

Summer Early and Late Winter 

Autumn

SPRING FLOOD 

Rise Peaks Recession

Figure 21. Bottom particulate organic carbon concentrations.

C40 Apalachicola River Quality Assessment
100,000

50,000

10,000

5000

CO

z

O 

O

tr

fc 1000

a: 

o 

o.

CO

z 

<

OC

O 

00

a: 

< 

o

o

a: 

o

500

100

50

10

Total suspended 

VFPOC

1

FPOC

CROC

Bottomload Organic 

Carbon

I

CHATTAHOOCHEE BLOUNTSTOWN WEWAHITCHKA SUMATRA

Figure 22. Annual paniculate organic carbon transport.

Nutrient and Detritus Transport in the Apalachicola River, Florida C41
Table 30. Daily detritus fraction transport at Sumatra, by periods, J une 3, 1979, through J une 2, 1980

[VFPOC, very fine particulate carbon; FPOC, fine particulate organic carbon; CPOC, coarse particulate organic carbon; BPOC, bottom load 

particulate organic carbon. Total suspended organic carbon = VFPOC + FPOC + CPOC; slight discrepancies due to rounding. All data shown 

in metric tons per day]

Period

Summer. ...........................

Autumn (early and late) .................

Winter. ............................

Spring flood rise ......................

Spring flood peaks. ....................

Spring flood recession ..................

Total suspended 

organic carbon

........ 42

........ 38

........ 52

........ 66

........ 335

........ 130

VFPOC

37

29

37

22

294

114

FPOC

4

8

14

39

32

13

CPOC

0.9

1.1

1.2

4.6

8.8

3.5

BPOC

0.1

0.31

0.90

1.00

0.51

1.05

plastic sheets distributed randomly at 14 plots in the 

Sweetwater and Brickyard transects (figs. 6 and 7). Summarized results for both inorganic and organic deposition 

are shown in table 31. Data for the individual collections 

are given in "Supplementary Data II."

The weight of material deposited on the plastic 

sheets varied widely because the sheets were located in 

extremely different environments where depth of flooding, 

velocity of flow, and litter fall differed. Plot 4 was the 

only sheet location not flooded during the investigation, 

so it served as a control area.

In the flood plain as a whole, most of the material 

deposited was inorganic. By contrast, the organic fraction 

was predominant at plot 4. The amount of organic material at plot 4 was higher than the amount at most other 

plots, especially those in swampy areas. Levee plots were 

subject to a great deal more deposition, both organic and 

inorganic, than swamp plots.

Error Analysis 

Water Budget

Systematic or additive error is error that accumulates in the same direction during each consecutive step. 

Compensating error occurs when measurement error is 

both plus and minus, so that the sum of a series of operations may have an absolute error smaller than many of the 

individual parts. The residuals shown in table 16 are 

primarily due to independent, nonadditive measurement 

and estimation errors. The total flow past the Sumatra 

gage during the various periods included residuals ranging 

from 54 percent to +9 percent. With the exception of 

the spring flood rise period, all errors were less than 10 

percent. The large negative residual for the spring flood 

rise period was the result of the 3-day discharge lag and 

flood-plain storage.The largest positive residual occurred 

during the spring flood recession, when much of the "lost

water" was recovered at Sumatra. For the three spring 

flood periods, the total residual ( + 0.53 km3 ) was 3.8 percent of the total flow past the Sumatra gage during those 

periods. The residual, or unexplained, discharge for the 

year was 0.84 km3 , or 2.9 percent. Although each component of the water budget is associated with an error estimated to be 5 percent or greater, the annual residual is 

smaller than 5 percent. Error compensation over the long 

term contributed to the decrease in the annual residual percentage relative to that of any single period. Similar longterm error compensation is suggested by the residuals of 

the separate subbasins (tables 14-16).

Winter (1981) reported probable error levels for different water balance components and various methods of 

measurement or calculation. His work dealt with lakes, 

but many of the conclusions apply to any aquatic system. 

Among the annual water balance error sources, 

streamflow (determined by a stage-discharge relation 

using a recording stage gage) was one of the most accurate at 5 percent per year. Precipitation (determined by 

areal averaging of National Weather Service rainfall data) 

is subject to 10 percent error in 1 year. Evaporation errors 

range from 10 to 15 percent per year. These may be 

reasonable estimates of the errors associated with the 

Apalachicola water-budget terms WO or VV7, P, and £T, 

respectively. Evapotranspiration was not determined by 

the methods discussed by Winter, but data from other 

studies (Qureshi, 1978; Brown, 1981) indicated that ET 

rates in Florida flood-plain environments are quite consistent for any given month. The ET term is thus judged accurate to at least 25 percent.

Ground-water estimates are probably the most uncertain of any of the Apalachicola water-budget terms; 

however, the amount of water involved is only 0.7 km3 , 

or 2.4 percent of the 28.61 km3 measured discharge for 

the entire basin. In the upper subbasin, there are enough 

data to make ground-water estimates fair to good; a 30 

percent error per year is presumed adequate. In the middle 

and lower subbasins, the ground-water component is near

C42 Apalachicola River Quality Assessment
Table 31. Deposition of material during 9 to 11 months 1 on plastic sheets randomly located at intensive plots

[Plot 4 was never flooded]

Deposition, in grams per square meter

Plots

All ...............

4 ................

All except 4 .........

Swamp2 ...........

Levee 3 ............

Number 

of 

sheets

....... 31

....... 4

....... 27

....... 14

....... 17

Organic

Mean

150 

180 

140 

60 

220

Standard 

deviation

180 

50 

190 

60 

210

Range

1.5-851 

137 -232 

1.5-851 

1.5-175 

18 -851

Mean

2,200 

110 

2,500 

520 

3,500

Inorganic

Standard 

deviation

5,100 

30 

5,400 

540 

6,700

Range

15-20,570 

80- 152 

15-20,570 

15- 1,856 

80-20,570

1 All sheets were in place during the heavy litter-fall period and the spring flood. Dates of removal of the sheets varied (see "Supplementary 

Data II").

2 Plots 1, 7, 12, 13, 15, 16, 17, and 18 (see fig. 6 and 7). 

3 Plots 3,4, 5,6, 11, and 14 (see fig. 6 and 7).

zero, and percentage errors become meaningless. An error 

of ±0.3 km3 per year is estimated in these reaches. Combining the three subbasins, the error, if additive, could be 

100 percent.

All stream discharge terms (WO, WI, and CR) are 

likely to be accurate, in part because they are based on 

frequent measurements. Stage readings recorded hourly 

are translated to daily discharge means, which are averaged over longer time periods. With such frequent measurements, independent, nonadditive measurement errors 

become negligible over the long term. Systematic errors in 

discharge estimates are possible. An inaccurate discharge 

measurement, for example, might displace the stage-discharge rating curve, affecting most or all daily means with 

errors of the same sign. All Apalachicola main channel 

sites have been frequently measured at various stages, 

however, giving strong documentation of the ratings.

Nutrient and Detritus Concentrations

As one means of evaluating the accuracy of waterquality data, a set of samples from two Apalachicola sites, 

Chattahoochee and Sumatra, were used for a standard-addition recovery test. Water samples were injected with 

measured volumes of standards from the EPA Environmental Monitoring Laboratory. Separate tests were conducted for nitrate, ammonia, and organic nitrogen, dissolved and total phosphorus, and total organic carbon. Each 

injected sample was accompanied by a natural sample (not 

injected), and both were handled and analyzed in the usual 

fashion. Reliability of the data was judged by how closely 

the results for injected samples reflected the sum of the 

natural concentration plus the known standard additions.

All standard-addition recoveries of nitrogen, carbon, 

and total phosphorus were within 11 percent of actual concentrations. The recovery efficiency for dissolved orthophosphate was lower, primarily because the concentrations were near the analytical detection limits and the precision of the analyses was ±0.01 mg/L. The absolute discrepancies were the same magnitude for dissolved and 

total phosphorus, but when converted to percentage recoveries, they are much better for total P.

Precision for some of the nutrient analyses was 

given by the U.S. Geological Survey Water Quality Laboratory's Services Catalog (Beetem and others, 1980). At 

the levels found in Apalachicola water, precision values 

for analyses of dissolved nitrogen fractions and dissolved 

orthophosphates ranged between 14 and 20 percent. No 

precision estimates were given for total carbon analyses.

An additional source of data used to evaluate the accuracy of phosphorus data came from having parallel 

analyses of reactive phosphate performed by a separate 

laboratory. Results from the Department of Oceanography 

laboratory at Florida State University were provided by P. 

N. Froelich (written commun., 1981) for samples collected in March and June 1980. Twelve values were available for comparison with results on duplicate samples 

from the U.S. Geological Survey National Water Quality 

Laboratory, Atlanta, Ga. After rounding all values to the 

nearest 0.01 mg/L, 8 of the 12 samples produced the same 

results from both laboratories: two were different by 0.01 

mg/L and two, by 0.02 mg/L.

The probable maximum errors for the nutrient-concentration data were estimated on the basis of control data 

from standard-addition tests and from the laboratories of 

USGS and Florida State University. Carbon and nitroNutrient and Detritus Transport in the Apalachicola River, Florida C43
gen data are estimated to be subject to 15 percent error, 

and phosphorus data, to a 25 percent error. Assuming 

these are random errors, as samples are pooled, the expected relative error becomes smaller. Hence, concentration data collected the same way and averaged over several months or a full year are subject to smaller errors.

Detritus measurements are subject to considerable 

sampling error because of the probability of nonuniform 

distribution of the material in the natural environment. 

Analytical methods to determine dry and ash weight of 

suspended material, however, are simple and nearly free 

of interference.

Detritus sampling methods were original for this investigation; thus there is no documentation as to their accuracy. Discrepancies between replicate detritus samples 

could be the result of either natural variability or inconsistencies in sampling procedures. Field tests of various detritus sampling techniques obtained results such as those 

illustrated in figure 13, suggesting that these methods 

were adequate for characterizing the detritus transport process. It is assumed that a 15 percent error may be associated with paniculate carbon transport. Even if substantially different, this error will have little effect on the 

overall carbon budget since most carbon transport is in 

soluble form.

Transport

By using the nutrient transport model derived from 

continuous streamflow records and discrete nutrient concentration measurements at interval midpoints, transport 

calculation errors were minimized (Scheider and others, 

1978). Errors associated with measurement of discharge 

and the precision of chemical analyses, however, are carried over into the calculation of transport. Using percentage error estimates for discharge and nutrient concentrations, transport errors are computed for each sample interval (the length of time represented by one water chemistry 

sample). The total transport error for a particular sample 

interval (combining discharge and concentration errors), 

or over a hydrologic period (combining errors for included 

sample intervals), are computed by the equation

E = (10)

where

E equals total error;

GJ equals error for /th component or sample interval; and

n equals number of component or sample intervals.

This formula was suggested by Winter (1981) as a 

good estimator for combining errors from various components. It can also be used to combine interval errors to determine long-term error, provided that the component errors (e/) are independent and not additive. This requirement is met by these data since both discharge and concentration data depended on measurements that were totally independent and were equally likely to be erroneous 

in either a high or a low direction. The results of calculation or errors using equation 10 with regard to annual nutrient transport are illustrated in figure 23. The error bars 

about each annual transport for the four main-stem river 

gage locations and the Chipola River below Dead Lake 

Outlet provide a means by which to judge differences 

among transport rates at different locations. A general 

downstream increase in nutrient transport is apparent, particularly for carbon. The actual increase between any two 

adjacent sites should not be overemphasized because of 

the overlapping error bars computed with equation 10.

DISCUSSION

Flood-Plain Role in 

Nutrient Transport

A central purpose of this investigation is the assessment of the role of the flood plain in nutrient transport in 

the Apalachicola River. Direct measurements of this role 

were not possible, but the various kinds of data that were 

gathered provided pieces of information that could be considered together to arrive at clues pertaining to wetland 

functions.

An enormous nutrient source is present in the 

Apalachicola flood plain. The dense bottom-land hardwood forest contains more than 1,500 trees per hectare 

(Leitman and others, 1983). This vegetation produces 

some 800 g/m2 of litter fall annually, which places it 

among the most productive of forests in warm temperate 

regions (Elder and Cairns, 1982). Much of the litter material is subject to rapid decomposition to both soluble and 

small-detrital nutrient residues.

The hydrology of the Apalachicola system, coupled 

with its high productivity, is critical to the potential nutrient flow from the flood plain. Leitman and others (1983) 

found that 57 percent of 223 sample points in the flood 

plain were in environments that are generally saturated or 

flooded during the dry season (autumn) and that all but 3 

of the 223 points were below the 2-year, 1-day high flood 

stage for the period 1958-80. During inundation, velocities in the flood plain range from 0 to 0.3 m/s, with 

most points subject to velocities of at least 0.1 m/s (Leitman and others, 1983). In channelized areas in the flood 

plain, velocities almost as high as the river flow may be 

observed during high flood stages.

C44 Apalachicola River Quality Assessment
CO

Z 

O

ho

trtUJ

2

5

TRANSPORT,

h- ^»

NUTRIEh

200,000

160,000

120,000

80,000

40,000

0

20,000

16,000

12,000 

8000

4000

0 

1600

1200

800

400 

0

i i i i i

I

 " 

-

CARBON x

j I I

-*"

NITROGEN

EXPLANATION

t Mean concentration 

-L and standard error 

for sites indicated

-

"*"

I * - 1 *

-

PHOSPHORUS

CHATTA- BLOUNTS- WEWA- DEAD SUMATRA

HOOCHEE TOWN HITCHKA LAKE

Figure 23. Annual nutrient transport at four Apalachicola River sites and the Chipola River Outlet at Dead Lake, showing error ranges.

Nutrient and Detritus Transport in the Apalachicola River, Florida C45
These hydrologic characteristics of the flood plain 

are important not only for transport of nutrients and detritus, but also, over the long term, for the very existence 

of the vegetation that produces that detritus. Leitman and 

others (1983) found high statistical correlations between 

forest type distribution and nine different water parameters, such as flood depths, velocity, and duration of flooding. Hence, hydrologic characteristics influence the type 

of detritus produced as well as the quantity transported.

High productivity of dense vegetation in the floodplain forest implies active uptake of nutrients, tending to 

counterbalance nutrient and detritus release. Nutrient uptake is likely to diminish concentrations of dissolved nutrients more than particulates (Stanley and Hobbie, 1981). 

The trends shown in figures 21 -23 indicate that concentrations of detritus increase in a downstream direction much 

more than do concentrations of dissolved or total organic 

carbon. This means that the solute:paniculate ratio, although large throughout the river, decreases appreciably in 

a downstream direction. The flood plain is the primary 

producer and consumer of carbon in the basin and must 

have a great deal to do with the change in solute:paniculate ratio. One of the net effects of the flood plain is conversion of some organic carbon from dissolved to paniculate species due to vegetative assimilation of dissolved 

carbon and subsequent release of organic material through 

litter deposition.

The annual residuals shown in tables 21, 25, and 29 

are all positive, indicating that nutrient input to the river 

cannot be totally balanced by the sum of precipitation, 

ground-water, and surface-water inflow. The residual 

values incorporate the combined errors of all components, 

but in the cases of carbon and phosphorus, such errors 

would not likely be additive such that we would observe 

the high positive R values shown on the tables. Floodplain-derived nutrients probably make up the difference. 

This seems an especially plausible explanation since the 

highest relative R value is for carbon, which is less likely 

to be retained by the wetland than is nitrogen or phosphorus (Peverly, 1982). Export of the three elements has 

also been documented in studies by Day and others (1977) 

of a swamp system in Louisiana very similar to the 

Apalachicola flood plain.

The nitrogen budget (table 25) shows a nearly precise balance between nitrogen import and export in the 

wetland. The annual nitrogen residual, although positive, 

was less than 1 percent of the total outflow at Sumatra and 

may be attributed to error. Wetlands do have the capacity, 

under certain circumstances, to retain nitrogen from 

through-flowing waters (Brinson, 1977; Sloey and others, 

1978). As an essential plant nutrient, nitrogen is likely to 

be retained in the forest ecosystem, at least during the 

growing season (Vitousek and Reiners, 1975). The waters 

of the Apalachicola system are nitrogen rich; however, 

with a nitrogen:phosphorus ratio in excess of 10, the system is probably not nitrogen-limited. Nitrogen fixation 

and denitrification within the flood-plain forest could provide most of the internal nitrogen needs. Excess nitrogen 

input might flow through the system quite readily under 

such conditions.

Variable values such as those for Blountstown may 

mean the values were correct or were artifacts caused by 

sampling or analytical error. It is assumed that all data are 

correct unless there is evidence of error, such as a sampling inconsistency. Data also may be rejected if they are so 

inconsistent with other data that they are judged unrealistic. In the case of the Blountstown carbon data, however, 

there was no justification for rejecting the data. The results serve to illustrate the value in considering increased 

time and area; as the perspective is changed from one 

period and subbasin to the full year and the entire basin, 

the fluctuations are more likely to balance each other and 

more realistic estimates may be derived.

A notable case in which a high negative R value 

was caused by abnormally low concentration is shown in 

table 24. In May 1980, the total nitrogen concentration 

was 0.68 mg/L at Sumatra, somewhat less than its usual 

range of 0.75-1.00 mg/L. A low nitrogen outflow estimate 

for the lower subbasin produced a high negative R value 

for the spring flood recession and for the entire year's 

budget for that subbasin.

Large negative residuals occurred in the spring flood 

rise period for all three nutrients in the lower subbasin (tables 20, 24, and 28). This was a reflection of the flood 

wave lag that produced a similar negative residual in the 

water budget for that period (table 16). The lag effect disappeared when data from all periods were combined into 

an annual value.

The phosphorus export:import ratio in the 

Apalachicola system (table 29) is comparable to that of 

carbon. The annual residual is positive and is an appreciable fraction (11 percent) of total transport at Sumatra, 

suggesting an overall export from the flood plain. This result is in contrast with some other studies (Brinson, 1977; 

Mitsch and others, 1979; Peverly, 1982) which show 

either net retention of phosphorus or a fluctuation between 

import and export. The large amount of detritus output 

from the Apalachicola flood plain may be a factor contributing to phosphorus export by providing a surface for 

sorption of the element.

In examining the entire set of data in tables 18-29, 

the reader should keep in mind that the main purpose of 

these data is to arrive at some realistic estimates for annual riverine yield. The purpose is not to highlight 

changes over short lengths of time or small geographic 

areas. Focusing on the narrow perspective reveals considerable variability in water flow and nutrient concentration. 

For example, table 19 shows that in the summer period, 

carbon inflow (C7 ) at Blountstown was 60 percent higher 

than carbon outflow at Wewahitchka. This produced a

C46 Apalachicola River Quality Assessment
large negative R value for that period and, eventually, for 

the entire year. The high C, at Blountstown in the summer 

period resulted from three extraordinarily high total organic carbon (TOC) concentrations in the samples collected at Blountstown in June, July, and August all of 

them greater than 12 mg/L. These high concentrations 

were not matched at other sites. A similar high TOC concentration at Blountstown occurred in November 1979, 

producing the high C/ in the late autumn season and subsequent high negative R value (table 19).

River Basin Nutrient Yield

Figures 24, 25, and 26 illustrate cumulative nutrient 

transport and changes with season, over the full year from 

June 3, 1979, through June 2, 1980. The scope is the entire basin. Y0 represents outflow at Sumatra, and Y,- represents inflow at Chattahoochee. It is evident that nutrient 

inflow was the largest single contributor to nutrient yield 

in the basin. The percentage of Y0 contributed by Y/ 

ranged from 40 percent (carbon in early September and 

nitrogen in late August) to more than 100 percent (phosphorus in early July). The sum of the remaining components, which were estimated from field data, is represented on the graphs (figs. 24-26) by the separation between the two lowermost curves. Nearly all of this quantity in each case is attributable to surface-water inflow 

from the Chipola River, embodied in the Ycr term.

Seasonal effects on nutrient transport were minor 

except during the spring flood periods. Rapid increases in 

cumulative transport occurred during the early stages of 

the spring flood, in March and April. Although carbon 

and phosphorus transport increased rapidly in the early 

flood stages, the inputs diminished considerably in the latter stages (late April and May), leaving a difference between input and outflow. This gap is the residual, shown 

by the shaded part in the illustrations. This residual 

amounts to 13 percent of the total annual carbon transport 

and 11 percent of the annual phosphorus transport; it is 

presumed to come principally from the flood plain. Floodinduced carbon export from the flood plain appears to 

have occurred primarily during the latter peaks and recession of the spring flood. The nitrogen residual was 1 percent of the annual transport, reflecting an approximate 

balance between export and import.

Transport of particulate organic matter is especially 

prone to sharp surges due to flooding. To illustrate this, 

figure 27 compares cumulative transport of all fractions of 

carbon at Sumatra with the transport curves that would be 

observed if the rates were constant throughout the year 

(using January 4, 1980, as the date for determining constant rate). Observed data in the spring months of 1980 

were offset considerably from the constant rate curves. On 

close inspection, the most critical "flushing periods" for

the different fractions appear to be quite distinguishable. 

For example, the principal CPOC surge occurred in April, 

while the FPOC was released somewhat earlier and began 

to slow down in April. Bottom-load material (BPOC) 

showed one of its greatest surges in November, coinciding 

with the period of heaviest litter fall, then increased again 

in the winter and spring periods as greater areas became 

inundated.

The characteristics of the water budget are such that 

the flood-plain role in nutrient transport is critical. The 

Apalachicola River water budget is heavily dominated by 

streamflow; all inputs and losses within the basin are 

small relative to the flow in the main channels. In the absence of major pollution sources, nutrient inputs associated with precipitation, ground water, and overland 

runoff are unlikely to appreciably augment the huge nutrient pool in the river water. The flood plain, with its substantial nutrient production and its direct, prolonged interaction with the flowing river water, is therefore the only 

factor in the basin that is likely to have considerable influence on the nutrient and detritus yield of the river.

It is not accurate to infer from this analysis that precipitation, ground-water flow, evapotranspiration, and 

other means of water and nutrient exchange in the 

Apalachicola basin are unimportant. They are minor only 

when compared with the total pool associated with 

streamflow. Rainfall and evapotranspiration rates in this 

warm temperate zone are higher than in most areas of the 

country (Qureshi, 1978), but they nevertheless have relatively little effect on overall streamflow (table 16).

Tables 21, 25, and 29 show that annual transport of 

carbon, nitrogen, and phosphorus was substantially greater 

at Sumatra than at Chattahoochee. Streamflow at Sumatra 

was also greater than at Chattahoochee (table 16). If the 

Sumatra outflow:Chattahoochee inflow ratios are derived 

from the annual basin-wide budgets of tables 16, 21, 25, 

and 29, and figure 22, the results are as follows:

Constituent Outflow: in flow ratio

Water ...................... 1.25

Carbon ...................... 1.50

Nitrogen ..................... 1.20

Phosphorus ................... 1.23

Total detritus .................. 1.41

VFPOC ..................... 1.25

FPOC ...................... 3.50

CPOC ..................... 70

Increased water flow without simultaneous nutrient 

inputs would simply result in lower nutrient concentrations 

and no change in nutrient transport. The outflow:inflow 

ratios show that this did not happen. Instead, there was a 

nutrient input that matched flow increase in the cases of 

nitrogen and phosphorus and exceeded flow increase in 

the case of carbon.

Nutrient and Detritus Transport in the Apalachicola River, Florida C47
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 C0 (outflow)

C (inflow)

B;;;::i..:r:l Estimated flood plain 

carbon contribution

JUNE JULY AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY

1979 I960

Figure 24. Cumulative carbon transport in the Apalachicola River basin from June 3,1979, through June 2, 1980.

C48 Apalachicola River Quality Assessment
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JUNE JULY AU6 SEPT OCT NOV DEC JAN FEB MAR APR MAY

1979 1980

Figure 26. Cumulative phosphorus transport in the Apalachicola River basin from June 3,1979, through June 2,1980.

C50 Apalachicola River Quality Assessment
£ 10,000

5000

1000

500

100

50

10

EXPLANATION

 TPOC Total particulate organic matter

0 VFPOC Very fine particulate organic matter

x FPOC Fine particulate organic matter

D CPOC Coarse particulate organic matter

® BPOC Bottom particulate organic matter

. 0

. 0

_ _ _ _ 

1 r U L

VFPOC

FPOC

CPOC

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a

/

BPOC

/

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1 1 1 1 1

JUNE JULY AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUNE

1979 1980

Figure 27. Observed versus constant rate (dashed line) transport of five particulate organic carbon fractions in the 

Apalachicola River basin from June 3, 1979, through June 2, 1980.

Nutrient and Detritus Transport in the Apalachicola River, Florida C51
The overall conclusion from this analysis is that the 

Apalachicola wetland functions as a natural transformerfiltration system for waters passing through the basin. Exchanges result in some net increase in organic carbon and 

phosphorus transport, much of it in the form of particulate 

matter (detritus), but no net increase or decrease in nitrogen transport.

The implied effects of such a wetland role on estuarine ecology are that it favors secondary productivity 

and a detrital-based food web. Primary productivity is 

usually limited by phosphorus in estuarine systems, particularly during spring runoff (Taft and Taylor, 1976). 

This is especially likely in the Apalachicola system, with 

its high nitrogen:phosphorus ratio which is not appreciably 

altered by interaction with the flood plain. With the limitation on primary production, heterotrophic activity assumes relatively greater importance in the estuarine food 

web. The heterotrophs depend on a plentiful source of organic material. Detrital loads in the river water discharging to the bay provide an excellent substrate for bacterial 

growth (Fenchel, 1970) and a base for support of a thriving population of detrital feeders (Darnell, 1961), including many economically valuable shellfish species.

An alternative view might be suggested by the total 

organic carbon data. If the dissolved fraction is the main 

energy source for the estuary, the flood-plain role would 

appear much less significant. As shown by the outflowiinflow ratio and the data in figure 22, the total organic 

transport at Sumatra is not greatly different from that at 

Chattahoochee. If the flood plain were not there, the 

riverine yield of total organic carbon might not be greatly 

reduced. This interpretation requires several assumptions: 

(1) dissolved organics are not converted to particulates in 

the river channel by such processes as precipitation, adsorption, and bioassimilation; (2) dissolved organics are 

not changed in the river channel to forms that are less 

bioavailable; and (3) dissolved rather than particulate organics are most important in sustaining the estuarine productivity. Further research would be needed to determine 

the validity of these assumptions.

Sources of Nutrients

Considerable attention has been given thus far to 

nutrient inflow from the flood plain to the river. It is important that other sources be examined also to approach a 

full understanding of the interaction of various components.

Currently (1981), nearly all nutrients entering the 

Apalachicola streamflow by intrabasin pathways, such as 

ground water and surface runoff, are natural in origin. Anthropogenic sources are minor owing to the relatively undisturbed character of the basin. Waste water effluents consist primarily of a few treatment plants serving small 

municipalities.

Industry and agriculture are more prevalent in the 

basins of the two headwater rivers, the Chattahoochee and 

the Flint. Effects of agriculture in southwest Georgia were 

studied recently by Radtke and others (1980). They found 

that agriculture did not produce high concentrations of 

chemical constituents in stream water, even during periods 

of storm runoff. They attributed this to the permeability of 

the soil, which permits extensive percolation and adsorption of materials from the water deposited on agricultural 

lands. A recent investigation of the upper Chattahoochee 

River basin (Stamer and others, 1978) found that nonpoint 

sources of nutrient loads contributed more nutrients to 

streamflow than point sources.

Atmospheric deposition, as precipitation and dry 

fallout, contributes significant amounts of nitrogen and 

phosphorus to the Apalachicola-Chipola basin. As shown 

in tables 18-29, however, these inputs are quite small relative to total nutrient loads in the river. Atmospheric inputs 

often constitute a major chemical influence on any lakes 

in the area that do not undergo a large water exchange. 

Such impacts of atmospheric deposition have been observed elsewhere (Elder and Home, 1978; Dethier, 1979). 

The Apalachicola River system, however, is continually 

replenished by the Chattahoochee and Flint Rivers, and atmospheric sources of nutrients are not significant.

Recent studies of precipitation chemistry in Florida 

have shown that nitrogen and phosphorus concentrations 

elsewhere in the state are generally somewhat higher than 

concentrations in the precipitation of the Apalachicola 

basin, while organic carbon concentrations are highly variable. Hendry and Brezonik (1980) found mean concentrations of organic carbon, nitrogen, and phosphorus at 

Gainesville, Fla., to be 9.5, 0.82, and 0.085 mg/L, respectively, all somewhat higher than the median concentrations found in this study at the Apalachicola sites (fig. 

18). Irwin and Kirkland (1980) monitored 24 bulk precipitation sites in Florida; a Tallahassee site had nitrogen and 

phosphorus concentrations comparable to those of the 

Apalachicola basin, but organic carbon concentration was 

considerably lower. Central and southern Florida nutrient 

concentrations were generally higher than Tallahassee 

concentrations. In general, the analytical results of 

Apalachicola bulk precipitation samples were consistent 

with what might be expected for a relatively undisturbed, 

densely forested area.

Flood-Plain Detritus Contributions

Some approximation of detritus transport can be 

drawn from detritus nets and plastic sheets used in the 

flood plain. Although these approaches give only rough 

estimates, they serve as a test of the determinations of 

flood-plain contributions to detritus and total detritus 

transport in the system. It is emphasized that the values

C52 Apalachicola River Quality Assessment
derived are for the sole purpose of testing earlier calculations; they are not quantitative and should not be treated 

as such.

Flood-Plain-Net Estimate of Detritus

tons at Sumatra. Coarse particulate carbon flow from the 

flood plain as estimated by the net collectors was, therefore, nearly equal to measured transport near the Sweetwater transect but more than an order of magnitude smaller than measured transport near the Brickyard transect.

The data from the nets used to collect detritus in the 

flood plain ("Supplementary Data I") can be used to estimate the amount of coarse particulate carbon transported 

from the flood plain. The data show considerable variability, as would be expected because of the differences in the 

sites where the detritus was collected; however, overall 

mean weights provide information that serves as a comparison with carbon transport measured in the river.

The amount of flood-plain water flow during the 

1980 flood rise and peak can be estimated from flow distribution data given by Leitman and others (1983, figs. 25 

and 26). The flood-plain part of the discharge at the 

Sweetwater transect was 27 percent at high stage 

(<2=2,490 m3/s on March 18) and 10 percent at medium 

stage (<2= 1,640 m3/s on March 11). At the Brickyard 

transect, the corresponding values were 44 percent 

(0=2,920 m3/s on March 19) and 35 percent (Q= 1,980 

m3/s on March 14). These percentages may be used to estimate actual flow in the flood plain during the 1980 

flood, assuming that the maximum percentage applies to 

the flood peaks period and the mid-stage percentage applies to the flood rise and recession periods. Flow percentages multiplied by total discharge values at Blountstown 

and Sumatra (WO in tables 13 and 15) give the following 

estimates for flood-plain flow:

Flood-plain flow, 

_3 in torf

Period Sweetwater

Rise.................. .0.15

Peaks..................1.84

Recession............. . . 36

Total 1980 flood 2.35

B r i ckya. rd

0.40

3.55

L£l

5.57

The mean concentration of coarse particulate organic material captured in the flood-plain nets was 0.09 g/ 

m3 at Sweetwater and 0.02 g/m3 at Brickyard ("Supplementary Data I"). Multiplying these values by the floodplain flow just calculated and by the factor 0.5 to account 

for the concentration of carbon in organic matter, one arrives at the estimates of 100 metric tons CPOC transport 

at Sweetwater and 60 metric tons CPOC transport at 

Brickyard. Actual transport determinations from the 

CPOC and BPOC samples collected in the river during the 

entire flood period were 160 metric tons at Blountstown 

(slightly downstream of Sweetwater) and 1,000 metric

Plastic-Sheet Estimate of Detritus

The organic deposition on plastic sheets (table 31) 

was considerably less than the 800 (g/m2)/yr litter-fall rate 

found by Elder and Cairns (1982). Presumably, the differences are due to losses from the sheets resulting from decomposition and flood scouring and, perhaps, to some 

other factors such as removal by animals or wind. It 

should be noted that the plastic sheets were in place for 

somewhat less than a full year (9 to 11 months); hence, 

the litter fall on them would be slightly less than the annual rate.

The organic deposition on the sheets at plot 4 was 

somewhat higher than the mean deposition at all other 

plots (table 31), suggesting that the lack of flooding at 

plot 4 resulted in less removal of litter fall. Under this assumption, the removal caused by flooding can be estimated by comparing plot 4 data with data from all other 

plots, after first correcting for such effects as collection 

time and forest-cover type.

The collection time effect, caused by the sheets 

being in place for less than 1 year, was corrected by subtracting from annual litter-fall amounts (Elder and Cairns, 

1982) the amounts for the months that were not sampled 

by the sheets. For example, the sheets at plot 4 were removed in early June 1980, after being in place for 9 

months, so the amount of litter-fall during June, July, and 

August was subtracted from the annual total to estimate 

actual litter fall on the sheets.

The plot locations do not correspond proportionally 

to the different forest-cover types in the intensive transects 

(Leitman and others, 1983). At the Brickyard transect, for 

example, two of the nine plots are on levees, yet only 5 

percent of the transect is composed of levee forest-cover 

types. The litter-fall data, as well as the plastic-sheet data, 

must be weighted according to the transect distance represented by each plot to more accurately characterize the 

entire transect. When this is done, the mean plastic-sheet 

sample weight (organic material only) for plots other than 

plot 4 is 89 g/m2 .

The results of these calculations are as follows:

Plastic

Litter sheet 

fan sample Loss 

(grams per square meter)

Plot 4....

All other

plots...

,733

.831

182

89

551

742

Percent 

age los

75

89

Nutrient and Detritus Transport in the Apalachicola River, Florida C53
A greater removal of organic material, amounting to 14 

percent of the total, is calculated for the flooded sites. Assuming that this difference is due to flood scouring, the 

annual carbon loss from the entire flood plain can be calculated. The organic material is considered to be 50 percent carbon.

(0.14) x [800(g/m2)/yr] x (0.5)=

56g C/m2/yr=56 metric tons C/km2/yr

The area of the flood plain above Sumatra is 393 km2 ; 

hence:

56 metric tons C/km2/yrx393 km2 ^

22,000 metric tons C/yr

This compares closely with the estimate of 27,000 metric 

tons C/yr (table 21) previously determined as the flood 

plain yield plus residual R.

Significance of Flood-Plain-Net and 

Plastic-Sheet Estimates

The flood-plain nets and plastic sheets provide two 

sources of data from within the flood plain which supplement the paniculate carbon transport measurements in the 

river. Both approaches depend on random samples taken 

at locations that differ widely in environmental conditions. 

The data are thus subject to considerable variability and 

should be treated as qualitative supporting evidence that 

substantial amounts of the riverine detritus originate in the 

flood plain.

The flow of coarse detritus in the flood plain, as determined by the net sampling, could account for nearly all 

CPOC and BPOC transport measured in the river. At the 

Sweetwater transect, the estimated detrital flow of 100 

metric tons in the flood plain was quite close to the total 

riverine transport of 160 metric tons measured at 

Blountstown. Presumably, the amount found at 

Blountstown had been transported into the river from the 

flood plain upstream. Some of the detritus sampled at the 

Sweetwater transect may have entered the river above 

Blountstown, and some may have entered below. Farther 

downstream, as the detrital load increases in the river 

owing to inputs along the way, the flood-plain detrital 

flow would be expected to become a continually smaller 

fraction of riverine detrital flow. The estimates from the 

Brickyard transect confirm this expectation.

The plastic-sheet approach to estimating flood-plain 

carbon flow further corroborates the findings of the other 

approaches. The fact that the final estimate of 22,000 metric tons of particulate organic carbon transport/year is 

quite close to the river sample amount of 27,000 metric 

tons/year is an indication that the method does provide 

realistic estimates.

Neither the stationary nets nor the plastic sheets provide data that show how far the organic particles move. 

The fact that they do move, however, suggests that some 

must move from the flood plain to the stream channels. 

The general flow downstream and toward the channels 

should prevent complete recycling of the materials within 

the flood-plain ecosystem.

Nutrient Yields for the 

Apalachicola-Chattahoochee-Flint River System

Annual nutrient yield converted to an areal basis 

(g/m2/yr, equivalent to metric tons/km2/yr) reveals sharp 

differences among various basins and the flood plain 

(table 32). Compared with the entire Apalachicola-Chattahoochee-Flint basin, the Apalachicola flood plain is extremely high in carbon and phosphorus yield per unit area. 

Carbon and phosphorus areal yields from the flood plain 

are more than 15 times greater than from the basin as a 

whole. The Apalachicola and Chipola basins exhibit more 

areal nutrient yield than the Chattahoochee-Flint basin. 

The nutrient yields of the Chattahoochee-Flint watersheds 

are apparently affected by nutrient retention in the 16 reservoirs in the system.

The nitrogen budget of the Apalachicola-Chattahoochee-Flint system is clearly distinct from the carbon 

and phosphorus budgets, as shown by the data in table 32. 

Nitrogen yield from the Apalachicola flood plain is the 

same as the yield from the basin as a whole. Another distinction is seen in the comparisons of the Apalachicola 

and Chipola drainage areas. The Apalachicola yields more 

carbon and phosphorus, but less nitrogen, than the 

Chipola. It should be stressed that these yields apply to 

net yield rather than gross yield, since they are based on 

output minus input. Hence, the data do not indicate 

whether actual nitrogen yield from the flood plain was low 

or nitrogen retention was high.

Carbon transport rates on an areal basis have been 

reported for a number of other systems and provide an interesting comparison with those shown in table 32. 

Schlesinger and Melack (1981) compiled the results of 

numerous studies from various ecosystem types and found 

that, with few exceptions, the carbon output from river 

watersheds ranges from 1 to 10 g/m2 annually. Factors 

that seemed to favor high yield included steep topographic 

relief, high runoff, high primary productivity, and production of detritus as litter fall rather than below ground productivity in root systems (as in grasslands). Wetland 

watersheds were shown to be among the most productive. 

A regression of total organic carbon transport versus 

watershed size indicated that the mean annual world carbon export rate from watersheds should be 7.2 g/m2 . Most 

measured amounts are found to be lower than this, however, with the exception of wetland areas.

C54 Apalachicola River Quality Assessment
Table 32. Nutrient yields, on an areal basis, for various drainage areas of the Apalachicola-Chattahoochee-Flint

River system

Drainage basin

Apalachicola-Chattahoochee-Flint . . 

Chattahoochee-Flint ...........

Apalachicola-Chipola ...........

Apalachicola. ................

Chipola ....................

Apalachicola flood plain .........

Area 

(km 2 )

50,800 

44,600 

6,200 

3,100 

3,100 

393

Annual output minus input 

(tons)

Carbon

213,800 

142,700 

71,100 

41,500 

29,600 

27,000

Nitrogen

21,480 

17,860 

3,620 

1,060 

2,560 

170

Phosphorus

1,652 

1,340 

312 

237 

75 

180

Carbon

4 

3 

12 

13 

10 

69

Areal yield 

(g/m 2 /yr)

Nitrogen

0.4 

.4 

.6 

.3 

.8 

.4

Phosphorus

0.03 

.03 

.05 

.08 

.02 

.46

Further evidence of the high nutrient yield of wetlands was provided by Mulholland and Kuenzler (1979). 

Compiling data from various wetland and upland watersheds, they found a close linear relation between annual 

runoff and carbon transport. The relation was quite different for the two watershed types, however, with the resulting conclusion that, given equal runoff, wetland watersheds would be expected to yield five times more carbon 

per unit area than upland watersheds. A large number of 

other studies, including those of Odum and de la Cruz 

(1967), Heald (1971), and Day and others (1977), have 

demonstrated high rates of carbon export from wetland 

systems. By contrast, Woodwell and others (1977) reported net carbon import in a Long Island salt marsh, an 

inconsistency that adds credence to the argument that wetlands can act as both sinks and sources of organic material 

(de la Cruz, 1979).

The carbon export from the Chattahoochee-Flint 

basin, limited as it is by the dams on the rivers, is less 

than the 7.2 g/m2/yr postulated by Schlesinger and Melack 

(1981) as a world average. The output from the 

Apalachicola part of the system is 13 g/m2/yr, well above 

average. The 69 g/m2/yr yield from the flood plain gives 

strong evidence that the wetland yield accounts for the 

high overall yield of the whole Apalachicola basin.

Areal yield of phosphorus in the Apalachicola basin 

is higher than in most other systems. Mitsch and others 

(1979) reported a phosphorus output of 0.34 g/m2/yr from 

an Illinois cypress swamp, which is 0.18 g/m2/yr lower 

than the Apalachicola flood-plain output. Other studies 

(Richardson and others, 1978; Whittaker and others, 

1979) have shown phosphorus export rates considerably 

lower (less than 0.02 g/m2/yr) for other, more dissimilar 

systems. Most reported nitrogen export rates from the 

same systems are also lower than that of the Apalachicola, 

although there is considerable variability. Such variability 

may be partially attributed to nitrogen assimilation rates,

which can have enormous seasonal variability (Stanley 

andHobbie, 1981).

It is commonly believed that wetland environments 

generally function as sinks for nitrogen and phosphorus 

(Brinson, 1977; Simpson and others, 1978). This has been 

documented (Sloey and others, 1978) where wetlands may 

be utilized for sewage treatment or other nutrient assimilation roles. The Apalachicola system shows an overall annual export of phosphorus and nearly a balance between 

import and export of nitrogen. In view of the seasonal variability seen for the various hydrologic periods and the 

changing output/input ratios described in the nutrienttransport section, it seems likely that the system does act 

as a nutrient sink for certain periods during each annual 

cycle.

Long-Term Factors Influencing 

Nutrient Transport

There is evidence that the nutrient and detritus 

transport measured in the 1979-80 study year may be considered a good indicator of what may be expected in other 

years. A great deal of historical stage and discharge record 

was examined by Leitman and others (1983). They found 

that during the entire period of record (1929 to 1980), the 

seasonal distribution of flow shows a strong tendency for 

flows greater than 1,000 m3/s to occur in the spring 

months each year. The completion of the Jim Woodruff 

Dam in 1957 did not appreciably alter this pattern. Regulation by dams, however, did have some effect in diminishing the extremes, as shown by slightly flatter flowduration curves since 1957. The 1980 mean discharge was 

slightly higher than the average for 1958-80, and the 1980 

spring flood had a 1-day peak of 4-year recurrence interval (0.25 probability).

Nutrient and Detritus Transport in the Apalachicola River, Florida C55
The 1979-80 nutrient data, in the context of the historical hydrologic record, suggest a long-range pattern of 

nutrient transport that is stimulated annually by spring 

floods. The annual flooding and the extensive natural bottom-land hardwood forest are the critical elements for 

continual high productivity and mobilization of nutrients 

in the system. The dams on the Chattahoochee and Flint 

Rivers and the Jim Woodruff Dam at the headwaters of 

the Apalachicola apparently have had little effect on the 

nutrient flow pattern, but any new dam or other construction in the Apalachicola basin that alters the integrity of 

the flood plain is likely to disrupt nutrient flow considerably.

There were no hurricanes or extremely severe 

rainstorms in the Apalachicola basin during 1979-80; 

hence, the effects of major storms could not be quantified. 

Hurricanes have struck the northwest Florida coast in the 

vicinity of the city of Apalachicola approximately 25 

times during the past century. Such storms would presumably produce extremely high rainfall and, in some cases, 

extreme winds which would dramatically alter the normal 

water and nutrient flow through the Apalachicola system. 

An example of the effects of a severe rainstorm in 1969 

in the adjacent Ochlockonee River basin was described by 

Bridges and Davis (1972). The amount of rainfall in that 

storm exceeded the 1 in 100-year probability, and Ochlockonee River floods substantially exceeded 50-year flood 

levels. Significant amounts of the discharge flowed 

through the flood plain during the storm. It should be 

noted that the hurricane season is between June and 

November. These storms, therefore, would have the effect 

of adding an additional flood in a normal low-flow period, 

rather than compounding the usual spring flood.

SUMMARY

The Apalachicola River in northwest Florida is 

formed by the confluence of the Chattahoochee and Flint 

Rivers and has a 50,800-square-kilometer drainage system 

encompassing parts of three states. With an average discharge of 640 m3/s at Chattahoochee, Fla., the 

Apalachicola is the largest river in Florida and ranks 21st 

in magnitude of discharge in the conterminous United 

States. The river falls 12 m in its 172-km course from 

Lake Seminole, at the Florida-Georgia state line, to 

Apalachicola Bay in the Gulf of Mexico. Each winter and 

spring, its rising waters flood the adjacent wetlands for 3 

to 5 months. The flood plain, which broadens downstream 

from 1 km wide just below Lake Seminole to more than 

8 km wide near the mouth, is thickly forested with cypress, tupelo, and mixed hardwood trees, which thrive on 

the periodic inundation. At the end of its course, the river 

empties into the Apalachicola Bay, which is one of the 

most productive shellfish regions in the United States.

The bottom-land hardwood forest, which occupies 

the 454 square mile Apalachicola River flood plain, has 

experienced several generations of cutting but retains the 

same variety and general distribution of tree species that 

existed prior to timber harvest. The production, decomposition, and transport of leaf litter byproducts in the 

Apalachicola basin are considered representative of undisturbed bottom-land hardwood ecosystems. The description 

of the flood-plain contribution to the overall transport of 

nutrients and detritus to Apalachicola Bay includes the 

following specific findings:

1. The water budget of the Apalachicola basin is heavily 

streamflow-dominated; water volumes involved in precipitation, ground-water flow, surface-water runoff, and 

evapotranspiration are relatively minor compared with 

main-stem flow.

2. Small errors of rating curves at the four main-stem gaging stations accounted for most of the possible waterbudget error. Total annual errors appeared very small 

because flow errors were largely compensating rather 

than additive. Water-budget calculations for seven time 

periods between June 3, 1979, and June 2, 1980, for 

three subbasins showed that the most satisfactory balances were obtained when longer periods and all three 

subbasins of the river/flood plain were combined.

3. Annual flooding, which usually occurs on the 

Apalachicola in late winter or early spring, causes appreciable surges in nutrient transport, especially in particulate organic form. During the 86-day flood event in 

1980, approximately half of the annual outflow of organic carbon, nitrogen, and phosphorus and 60 percent 

of the detritus were transported past Sumatra, the final 

main-stem gaging station.

4. Total annual organic carbon outflow at Sumatra in 

1979-80 was 50 percent higher than inflow at Chattahoochee. This increase was greater than the 25 percent 

increase in streamflow. Nitrogen and phosphorus increases, on the other hand, were similar to the discharge 

increase, indicating that the basin input of these elements to the river just matched the river's gain in water 

volume.

5. Flood-plain detritus nets used to estimate flood-period 

transport of coarse particulate organic carbon measured 

substantial flood-plain transport at the Sweetwater and 

Brickyard transects. Bottom load and suspended detritus 

transport in the main-stem river channel increased 

downstream.

6. Plastic sheets were used in combination with litter-fall 

estimates to make a passive net estimate of detritus 

transport. The amount of annual organic carbon removal 

calculated from these data was close to the amount determined by actual measurements.

7. On an areal basis, the Apalachicola basin exports greater quantities of carbon (13 g/m2/yr) and phosphorus 

(0.08 g/nr/yr) than most watersheds. Some nutrient exC56 Apalachicola River Quality Assessment
port can be attributed to flood-plain contributions, although the flood plain also acts as a nutrient sink during 

certain periods of the year.

8. Over the long term, the system is dependent on annual 

spring floods and a healthy, productive, bottom-land 

hardwood forest in the flood plain to maintain nutrient 

and detritus flow to the bay. In the absence of major alterations to the system, the floods and the flood-plain 

forest will continue to be present each year and the annual nutrient-flow pattern should continue.

SELECTED REFERENCES

Avery, T. E., 1967, Forest measurements: New York, McGrawHill, 290 p.

Beetem, W. A., Friedman, L. C., Ferryman, G. R., and Watterson, C. A., eds., 1980, 1981 Water Quality Laboratory services catalog: U.S. Geological Survey Open-File Report 80- 

1279, 251 p.

Brakensiek, D. L., Osborn, H. B., and Rawls, W. J., coordinators, 1979, Field manual for research in agricultural hydrology: U.S. Department of Agriculture, Agriculture Handbook 

224, 547 p.

Bridges, W. C., and Davis, D. R., 1972, Flood of September 

20-23, 1969, in the Gadsden County area, Florida: Florida 

Bureau of Geology Information Circular 79, 37 p.

Brinson, M. M., 1977, Decomposition and nutrient exchange of 

litter in an alluvial swamp forest: Ecology, v. 58, no. 3, p. 

601-609.

Brown, Eugene, Skougstad, M. W., and Fishman, M. J., 1970, 

Methods for collection and analysis of water samples for dissolved minerals and gases: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 5, Chap. 

Al, 160 p.

Brown, Sandra, 1981, A comparison of the structure, primary 

productivity, and transpiration of cypress ecosystems in 

Florida: Ecological Monographs, v. 51, no. 4, 403-427.

Buchanan, T. J., and Somers, W. P., 1968, Stage measurement 

at gaging stations: U.S. Geological Survey Techniques of 

Water-Resources Investigations, Book 3, Chap. A7, 28 p.

 1969, Discharge measurements at gaging stations: U.S. 

Geological Survey Techniques of Water-Resources Investigations, Book 3, Chap. A8, 65 p.

Daniel C. C., Ill, Wilder, H. B., and Weiner, M. S., 1979, 

Water quality of the French Broad River, North Carolina; An 

analysis of data collected at Marshall, 1958-77: U.S. Geological Survey Water-Resources Investigations 79-87, 53 p.

Darnell, R. M., 1961, Trophic spectrum of an estuarine community based on studies of Lake Pontchartrain, Louisiana: Ecology, v. 43, no. 3, p. 553-568.

Day, J. W., Butler, T. J., and Conner, W. H., 1977, Productivity and nutrient export studies in a cypress swamp and lake 

system in Louisiana, in Wiley, M. L., ed., Estuarine processes, v. 2: New York, Academic Press, p. 255-269.

de la Cruz, A. A., 1979, Production and transport of detritus in 

wetlands, in Wetland functions and values The state of our

understanding: National Symposium on Wetlands, Lake 

Buena Vista, Florida, 1978, Proceedings, p. 162-174.

Dethier, D. P., 1979, Atmospheric contributions to stream water 

chemistry in the North Cascade Range, Washington: Water 

Resources Research, v. 15, no. 4, p. 787-794.

Edwards, M. D., 1977, The National Water Data Exchange 

(NAWDEX): U.S. Geological Survey Open-File Report 77- 

259,9 p.

Elder, J. F., and Cairns, D. J., 1982, Production and decomposition of forest litter fall on the Apalachicola River flood 

plain, Florida: U.S. Geological Survey Water-Supply Paper 

2196, Chap. B, 42 p.

Elder, J. F., and Home, A. J., 1978, Ephemeral cyanophycean 

blooms and their relationships to micronutrient chemistry in 

a southern California reservior: University of California, 

Sanitary Engineering Research Laboratory Report 78-1, 182

PFenchel, Tom, 1970, Studies on the decomposition of organic 

detritus derived from the turtle grass Thallassia testudinum: 

Limnology and Oceanography, v. 15, no. 1, p. 14-20.

Galloway, J. N., and Likens, G. E., 1976, Calibration of collection procedures for the determination of precipitation chemistry: Water, Air, and Soil Pollution, v. 6, p. 241-258.

Goerlitz, D. F., and Brown, Eugene, 1972, Methods for analysis 

of organic substances in water: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 5, Chap. 

A3, 40 p.

Greeson, P. E., ed., 1978, River-quality assessments: American 

Water Resources Association symposium, Tucson, 1977, 

Proceedings, 191 p.

Guy, H. P., and Norman, V. W., 1970, Field methods for measurement of fluvial sediment: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 3, Chap. 

C2, 59 p.

Heald, E. J., 1971, The production of organic detritus in a south 

Florida estuary: University of Miami Sea Grant Program, 

Technical Bulletin 6, 110 p.

Hendry, C. D., and Brezonik, P. L., 1980, Chemistry of precipitation at Gainesville, Florida: Environmental Science and 

Technology, v. 14, p. 843-849.

Hutchison, N. E., compiler, 1975, WATSTORE user's guide: 

U.S. Geological Survey Open-File Report 75- 

426, v. 1, 300 p.

Irwin, G. A., and Kirkland, R. T., 1980, Chemical and physical 

characteristics of precipitation at selected sites in Florida: 

U.S. Geological Survey Water-Resources Investigations 80- 

81, 70p.

Kilkus, S. P., LaPerriere, J. D., and Bachman, R. W., 1975, 

Nutrients and algae in some central Iowa streams: Journal of 

Water Pollution Control Federation, v. 47, no.7, p. 1870- 

1879.

Kwader, Thomas, and Schmidt, Walter, 1978, Top of the Floridan aquifer of northwest Florida: Florida Bureau of Geology 

Map Series 86.

Leitman, H. M., Sohm, J. E., and Franklin, M. A., 1983, Wetland hydrology and tree distribution of the Apalachicola 

River flood plain, Florida: U.S. Geological Survey WaterSupply Paper 2196, Chap. A, 52 p.

Livingston, R. J., Iverson, R. L., Estabrook, R. H., Keys, V. 

E., and Taylor, John, Jr., 1974, Major features of the

Nutrient and Detritus Transport in the Apalachicola River, Florida C57
Apalachicola Bay system physiography, biota, and resource 

management: Florida Scientist, v. 37, no. 4, p. 245-271.

Livingston, R. J., and Joyce, E. A., Jr., eds., 1977, Proceedings of the conference on the Apalachicola drainage system; 

Florida Department of Natural Resources: Marine Research 

Laboratory, Research Publication 26, 177 p.

Livingston, R. J., Kobylinski, G. J., Lewis, F. G., Ill, and 

Sheridan, P. F., 1976, Long-term fluctuations of epibenthic 

fish and invertebrate populations in Apalachicola Bay, 

Florida: Fishery Bulletin, v. 74, no. 2, p. 311-321.

Mattraw, H. C., Jr., and Elder, J. F., 1980, Nutrient yield of 

the Apalachicola River flood plain, Florida River-quality 

assessment plan: U.S. Geological Survey Water-Resources 

Investigations 80-51, 21 p.

Menzel, D. W., Hulings, N. C., and Hathaway, R. R., 1966, 

Oyster abundance in Apalachicola Bay, Florida, in relation to 

biotic associations influenced by salinity and other factors: 

Gulf Research Reports, v. 2, no. 2, p. 73-96.

Mitsch, W. J., Dorge, C. L., and Wiemhoff, J. R., 1979, 

Ecosystem dynamics and a phosphorus budget of an alluvial 

cypress swamp in southern Illinois: Ecology, v. 60, no. 6, p. 

1116-1124.

Mulholland, P. J., and Kuenzler, E. J., 1979, Organic carbon 

export from upland and forested wetland watersheds: Limnology and Oceanography, v. 24, no. 5, p. 960-966.

Naiman, R. J., and Sedell, J. R., 1979, Characterization of particulate organic matter transported by some Cascade Mountain streams: Journal of the Fisheries Research Board of 

Canada, v. 36, no. 1, p. 17-31.

Odum, E. P., and de la Cruz, A. A., 1967, Paniculate organic 

detritus in a Georgia salt marsh Estuarine ecosystem, in 

Lauff, G. H., ed.. Estuaries: Washington, D.C., American 

Association for the Advancement of Science Pub. 83, p. 383- 

388.

Oesterling, M. L., and Evink, G. L., 1977, Relationship between Florida's blue crab population and Apalachicola Bay, 

in Livingston, R. J., and Joyce, E. A., Jr., eds.. Proceedings 

of the conference on the Apalachicola drainage system; 

Florida Department of Natural Resources: Marine Research 

Laboratory, Research Pub. 26, p. 101-121.

Pascale, C. A., and Wagner, J. R., 1982, Water resources of the 

Ochlockonee River area, northwest Florida: U.S. Geological 

Survey Water-Resources Investigations Open-File Report 81- 

1121, 114p.

Peverly, J. H., 1982, Stream transport of nutrients through a 

wetland: Journal of Environmental Quality, v. 11, no. 1, p. 

38-41.

Qureshi, Zia, 1978, Surface water resources of northwest 

Florida: Water Resources Bulletin, v. 14, no. 3, p. 710-718.

Radtke, D. B., McConnell, J. B., and Carey, W. P., 1980, A 

preliminary appraisal of the effects of agriculture on stream 

quality in southwest Georgia: U.S. Geological Survey WaterResources Investigations Open-File Report 80-771, 40 p.

Richardson, C. J., Tilton, D. L., Kadlec, J. A., Chamie, J. 

P. M., and Wentz, W. A., 1978, Nutrient dynamics of northern wetland ecosystems, in Good, R. E., and others, eds., 

Freshwater wetlands, ecological processes and management 

potential: New York, Academic Press, p. 217-241.

Rosenau, J. C., Faulkner, G. L., Hendry, C. W., Jr., and Hull, 

R. W., 1977, Springs of Florida: Florida Bureau of Geology

Bulletin 31 (revised), 461 p.

Rosenau, J. C., and Meadows, P. E., 1977, Potentiometric surface of the Floridan aquifer in the Northwest Florida Water 

Management District, May 1976: U.S. Geological Survey 

Water-Resources Investigations Open-File Report 77-2, map.

Scheider, W. A., Moss, J. J., and Dillan, P. J., 1978, Measurement and uses of hydraulic and nutrient budget, in Lake restoration, proceedings of the national conference, August 22- 

24, 1978, Minneapolis, US EPA 440/5-79-001, p. 77-83.

Schlesinger, W. H., and Melack, J. M., 1981, Transport of organic carbon in the world's rivers: Tellus, v. 33. no. 2, p. 

172-187.

Simpson, R. L., Whigham, D. F., and Walker, Raymond, 1978, 

Seasonal patterns of nutrient movement in a freshwater tidal 

marsh, in Good. R. E.. and others, eds.. Freshwater wetlands, ecological processes and management potential: New 

York, Academic Press, p. 243-257.

Skougstad, M. W., Fishman, M. J., Friedman, L. C., Erdmann, 

D. E., and Duncan, S. S., eds., 1979, Methods for determination of inorganic substances in water and fluvial sediments: 

U.S. Geological Survey Techniques of Water-Resources Investigations, Book 5, Chap. Al, 626 p.

Sloey, W. E., Spangler, F. L., and Fetter, C. W., Jr., 1978, 

Management of freshwater wetlands for nutrient assimilation, 

in Good, R. E., and others, eds.. Freshwater wetlands, 

ecological processes and management potential: New York, 

Academic Press, p. 321-340.

Smoot, G. F., and Novak, C. E., 1969, Measurement of discharge by the moving-boat method: U.S. Geological Survey 

Techniques of Water-Resources Investigations, Book 3, 

Chap. All, 22 p.

Stamer, J. K., Cherry, R. N., Faye, R. E., and Kleckner. R. 

L., 1978, Magnitudes, nature, and effects of point and nonpoint discharges in the Chattahoochee River basin, Atlanta to 

West Point Dam, Georgia: U.S. Geological Survey Open-File 

Report 78-577, 74 p.

Stanley, D. W., and Hobbie, J. E., 1981, Nitrogen recycling in 

a North Carolina coastal river. Limnology and Oceanography, v. 26, no. 1, p. 30-42.

Taft, J. L., and Taylor, W. R., 1976. Phosphorus dynamics in 

some coastal plain estuaries, in Wiley, M. L., ed., Estuarine 

processes, v. 1: New York, Academic Press, p. 79-89.

Thornthwaite, C. W., and Mather, J. R., 1957, Instructions and 

tables for computing potential evapotranspiration and the 

water balance: Drexel Institute in Technology Laboratory of 

Climatology, Publications in Climatology, v. 10, no. 3, p. 

185-306.

U.S. Army Corps of Engineers, Mobile District, 1976, 

Apalachicola, Chattahoochee, and Flint Rivers, Alabama, 

Florida, and Georgia, Final impact statement operation and 

maintenance: Mobile, Ala. 179 p.

U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Office of Coastal Zone Management, 

and State of Florida, Department of Environmental Regulation, Bureau of Coastal Zone Managment, 1979, Final environmental impact statement, Apalachicola River and bay 

estuarine sanctuary: Washington, U.S. Government Printing 

Office, 48 p. 13 app.

U.S. Fish and Wildlife Service, 1979, Evaluation of alternatives 

report for Corps of Engineers study of navigational improveC58 Apalachicola River Quality Assessment
ments of the Apalachicola River below Jim Woodruff Dam, 

Florida: Unpublished report on file in Panama City, Fl., office of U.S. Fish and Wildlife Service, 82 p.

U.S. Geological Survey, 1980-82, Water resources data for 

Florida Northwest Florida: Annual reports as follows: 1980, 

Water-Data Report FL79-4; 1981, Water-Data Report FL80- 

4; 1982, Water-Data Report FL81-4.

Velz, C. J., 1970, Applied stream sanitation: New York, Wiley 

Interscience, John Wiley & Sons, 619 p.

 1978, River-quality assessment A rational scientific 

basis for pollution control and water-quality management, in 

Greeson, P. E., ed., River-quality assessments, Tucson, 

Ariz., 1977, Proceedings: Minneapolis, Minn., American 

Water Resources Association, p. 3-10.

Vitousek, P. M., and Reiners, W. A., 1975, Ecosystem succession and nutrient retention A hypothesis: Bioscience, v. 25, 

no. 6, p. 376-381.

Whitehead, H. C., and Feth, J. H., 1964, Chemical composition 

of rain, dry fallout, and bulk precipitation an Menlo Park, 

California, 1957-59: Journal of Geophysical Research, v. 69, 

p. 3319-3333.

Whittaker, R. H., Likens, G. E., Bormann, F. H., Eaton, J. S., 

and Siccama, T. G., 1979, The Hubbard Brook ecosystem 

study Forest nutrient cycling and element behavior: Ecology, v. 60, No. 1, p. 203-220.

Winter, T. C., 1981, Uncertainties in estimating the water balance of lakes: Water Resources Bulletin, v. 17, no. 1, p. 82- 

115.

Woodwell, G. M., Whitney, D. E., Hall, C. A. S., and 

Houghton, R. A., 1977, The Flax Pond ecosystem study 

Exchanges of carbon in water between a salt marsh and Long 

Island Sound: Limnology and Oceanography, v. 22, no. 5, p. 

833-838.

Nutrient and Detritus Transport in the Apalachicola River, Florida C59
SUPPLEMENTARY DATA I

Flood-plain detritus data from stationary nets located randomly on the 

flood plain during the spring flood, 1980. All locations were on or near 

the Sweetwater and Brickyard transects.

Date 

collected 

(1980)

3/11

3/12

3/12

3/18

3/18

3/26

3/26

4/02

4/02

4/23

3/14

3/14

3/17

3/17

3/19

3/19

3/27

3/27

4/03

4/28

4/28

Duration 

of 

sampling 

(hrs:min)

1:00

5:10

21:00

1:30

21:00

4:00

3:10

4:30

6:30

2:40

23:05

24:00

7:30

4:35

4:10

5:10

5:30

4:05

3:30

4:15

5:50

Flowthrough 

volume 

(m 3 )

Sweetwater transect

537

119

2,068

393

378

1,116

734

2,254

725

1,290

Brickyard transect

4,741

1,399

1,321

1,194

1,511

861

1,170

1,300

308

667

242

Detritus concentration, 

in mg/m 3

Inorganic

160

110

0.3

16

18

2

9

4

30

4

34

1

62

3

0.6

6

2

2

12

3

10

Organic

260

390

0.6

22

20

i

14

6

49

8

54

2

108

6

1.4

9

6

4

26

5

20

C60 Apalachicola River Quality Assessment
SUPPLEMENTARY DATA II

Deposition on plastic sheets randomly placed in Sweetwater and Brickyard plots on or about September 1, 1979, 

and collected on the date indicated. Coarse (>1 mm) and fine (<1 mm) fractions are given for most samples; for 

others, only total samples were analyzed. The area of all sheets was 1 m2 , except 4D, which was 4 m2 .

Plot

1 . . . .

3 . . . .

4 . . . .

5 . . . .

6 . . . .

7 ....

11 ....

12 ....

13 ....

14 ....

15 ....

16 ....

17 ....

18 ....

Sheet

A. . . . .

A. . . . .

B . . . . .

C . . . . .

A. . . . .

B . . . . .

C . . . . .

D. . . . .

A. . . . .

B . . . . .

C . . . . .

A. . . . .

B . . . . .

C . . . . .

A . . . . .

B . . . . .

C . . . . .

A. . . . .

B . . . . .

C . . . . .

A. . . . .

C .....

A. ....

B .....

C .....

A. ....

B .....

c

A. ....

B .....

A. ....

Collection 

date 

(1980)

8/4

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

6/3

7/9

8/5

8/5

8/5

8/5

5/6

6/6

5/6

8/5

O 1C Q/t)

8/5

8/5

8/5

8/5

Inorganic deposition, 

in grams 

per square meter

Coarse

31

4

143 

101 

86

91

70

45 

112 

169

0.3 

1.1 

3

379

22 

53

11 

36

38 

255 

12

1 

53

73

75 

45

10

Fine

320

223

9 

6 

3

122

230

823 

1,378 

287

424 

122 

1,853

205

419 

509

195 

769

18,699 

11,643 

20,559

106

38

1,403

58 

581

5

Total

351

1,075 

1,787 

227

152 

107 

89 

80

213 

828 

300

868 

1,490 

456

424 

123 

1,856

584

441 

562

206 

805

18,737 

11,898 

20,571

107 

91

1,476

133 

626

15

Organic deposition, 

in grams 

per square meter

Coarse

58

- 2

230 

208 

145

24

24

14 

95 

68

0.2 

0.8

2

81

23 

60

15 

47

25 

179 

14

1 

21

49

38 

17

6

Fine

94

16

2 

4

2

6

8

68 

135 

24

2.4 

0.7 

11

22

36

44

17 

81

319 

369 

179

9 

3

126

5 

58

1

Total

152

284 

851 

18

232 

212 

147 

137

30 

130

32

82 

230 

92

2.7 

1.5 

13

103

59 

104

32 

128

345 

548 

193

10

24

175

43 

75

7

Nutrient and Detritus Transport in the Apalachicola River, Florida C61
Metric Conversion Factors

For readers who prefer to use inch-pound units rather than metric units, the conversion factors for the terms used in this report are listed 

below:

Multiply metric unit

jum (micrometer)

mm (millimeter)

m (meter)

km (kilometer)

m/s (meter per second)

m2 (square meter)

ha (hectare)

km2 (square kilometer)

m3 (cubic meter)

L (liter)

m3 /s (cubic meter per second)

km3 (cubic kilometer)

mL (milliliter)

mg (milligram)

g (gram)

kg (kilogram)

t (metric ton)

t/ha (metric ton per hectare)

t/km2 (metric ton per square kilometer)

g/m2 (gram per square meter)

°C (degree Celsius)

mg/L (milligrams per liter)

Mg/L (micrograms per liter)

By

Length

0.00003937

.03937

3.281

1.094

.6214

3.281

Area

10.76

1.196

0.0002471

2.471

0.3861

Volume

35.31

1.308

0.0008107

264.2

1.0567

35.3145

0.2399

810,700

264,200

0.0338

Mass

0.0000353

0.0353

0.0022

2.2046

2,204.6

1.1023

892.18

0.4461

8.9218

0.004461

8.9218

Temperature

1.8 (+32°)

Concentration

1.0

1.0

To obtain inch-pound unit

in. (inch)

in. (inch)

ft (foot)

yd (yard)

mi (mile)

ft/s (Foot per second)

ft square foot

yd 2 (square yard)

acre

acre

mi 2 (square mile)

ft 3 (cubic foot)

yd3 (cubic yard)

acre-ft (acre-foot)

gal (gallon)

qt (quart)

ft /s (cubic foot per second)

mi3 (cubic mile)

acre-ft (acre-foot)

Mgal (million gallons)

oz (fluid ounce)

oz (ounce)

oz (ounce)

Ib (pound)

Ib (pound)

Ib (pound)

short (ton)

Ib/acre (pound per acre)

ton per acre

Ib/acre (pounds per acre)

tons per acre

Ib/acre (pound per acre)

F (degree Fahrenheit)

ppm (parts per million)

ppb (parts per billion)

C62 Apalachicola River Quality Assessment

U.S. GOVERNMENT PRINTING OFFICE: 1984-461-433:410