c S"

New3 3
Changes in the Organic Material in 

Lakes in the Blast Zone of 

Mount St. Helens, Washington

By D. M. McKnight, J. M. Klein, and R. C. Wissmar

Hydrologic Effects of the Eruptions 

of Mount St. Helens, Washington, 1980

U.S. GEOLOGICAL SURVEY CIRCULAR 850-L

1984
United States Department of the Interior

WILLIAM P. CLARK, Secretary

Geological Survey

Dallas L. Peck, Director

Free on application to the Branch of Distribution, Eastern Region, U. S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Abstract ................................

Introduction .............................

Description of blast-zone lakes ...............

Physical characteristics .................

Chemical characteristics .................

Inorganic constituents ..............

Organic constituents ................

Biological characteristics ................

Methods ................................

Results and discussion .....................

Dissolved and suspended organic carbon ... 

Spirit Lake and South Fork Castle Lake. 

Coldwater Lake ....................

St. Helens Lake....................

Fractionation of dissolved organic material. . . 

Characterization of aquatic humic substances.

Page Page

1 Results and discussion Continued

1 Identification of organic compounds ........ 15

3 South Fork Castle Lake .............. 15

3 Neutral organic compounds ........ 16

6 Organic acids ................... 18

6 Spirit Lake ........................ 18

6 Neutral organic compounds ........ 18

7 Organic acids ................... 19

7 Coldwater Lake ..................... 19

7 Neutral organic compounds ........ 19

7 Organic acids ................... 19

8 Toutle and Cowlitz Rivers ............. 19

10 Summary and conclusions .................... 19

11 References cited............................ 25

11 Supplementary data ........................ 26

14

ILLUSTRATIONS

Page 

FIGURE 1. Map of the blast zone of Mount St. Helens showing the dissolved organic-carbon concentrations of

several lakes sampled on September 11, 1980 ....................................... 2

2. Aerial photographs of South Fork Castle Lake on: A-July 20, 1980; B-November 11, 1980; C-March 1,

1981; and D-July 27, 1981 ...................................................... 4

3. Graph showing concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of Spirit Lake during the summer of 1981 ................................... 10

4. Graph showing concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of South Fork Castle Lake during the summer of 1981 ......................... 11

5. Graph showing concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of Coldwater Lake during the summer of 1981................................ 13

6. Graph showing concentration of dissolved and suspended organic carbon in the epilmnion and hypolimnion of St. Helens Lake during the summer of 1981 ............................... 13

III
TABLES

Page 

TABLE 1. Concentration of selected major cations, anions, and trace metals in Spirit Lake, March 28, 1980, and

June 6, 1980 ................................................................ 6

2. Concentrations of some major cations and trace metals in South Fork Castle Lake on September 11,

1980, and May 1, 1981......... ............................................... 6

3. Organic carbon concentrations in four representative lakes in the blast zone of Mount St. Helens during

the summer 1981............................................................. 8

4. Fractionation of dissolved organic carbon in surface waters in the blast zone of Mount St. Helens. .... 9

5. Characteristics of aquatic fulvic acids isolated in samples from lakes in the blast zone of Mount

St. Helens.................................................................. 12

6. Neutral organic compounds identified in a sample from South Fork Castle Lake, March 27, 1981. ..... 14

7. Neutral organic compounds identified in a sample from South Fork Castle Lake, May 1, 1981..... 15

8. Comparison of neutral organic compounds identified in samples from South Fork Castle Lake, 

September 11, 1980, and before (March 27, 1981) and after (May 1, 1981) aeration and dilution 

by snowmelt ............................... ................................ 16

9. Organic acids identified in a sample from South Fork Castle Lake, March 27, 1981 ............. 17

10. Organic acids identified in a sample from South Fork Castle Lake, May 1, 1981................ 18

11. Comparison of organic acids identified in samples from South Fork Castle Lake and in volcanic

ash .................. .................................................... 20

12. Neutral organic compounds identified in a sample from Spirit Lake, April 30, 1981 ............. 22

13. Organic acids identified in a sample from Spirit Lake, April 30, 1981 ........................ 22

14. Organic acids identified in samples from Spirit Lake, September 11, 1980, and April 30, 1981, and in

volcanic ash ................................................................ 23

15. Neutral organic compounds identified in a sample from Coldwater Lake, April 30, 1981 ......... 24

16. Organic acids identified in a sample from Coldwater Lake, April 30,1981, and comparison with organic

material in volcanic ash ....................................................... 24

17. Organic acids identified in samples from the Toutle and Cowlitz Rivers, and in volcanic ash ...... 25

18. Neutral organic compounds and organic acids identified in samples from several lakes in the blast

zones of Mount St. Helens ..................................................... 26

METRIC CONVERSION FACTORS

B\- To obtain

foot (ft) 0.3048 meter (m)

acre 4046.87 square meters (m2 )

mile 1.609 kilometer

acre-foot 0.001233 cubic hectometer (hm3 )

IV
HYDROLOGIC EFFECTS OF THE ERUPTIONS OF 

MOUNT ST. HELENS, WASHINGTON, 1980

CHANGES IN THE ORGANIC MATERIAL IN LAKES IN THE BLAST ZONE 

OF MOUNT ST. HELENS, WASHINGTON

By Diane M. McKnight, John M. Klein and Robert C. Wissmar

ABSTRACT

The productive conifer forest that had surrounded Mount 

St. Helens, Washington, was destroyed by the cataclysmic 

eruption of the volcano on May 18, 1980. Large quantities of 

organic material were introduced into the nearby surface 

waters, either as soil and plants incorporated into pyroclastic, mudflow, or debris-avalanche deposits, or as blowndown timber swept into lakes by the lateral blast of hot 

volcanic gases. The resulting major increases in the concentration of dissolved organic material were one of the 

most significant changes in the water chemistry of surface 

waters of the blast zone. The concentrations of dissolved 

organic material were greater in lakes directly associated 

with pyroclastic, mudflow, and debris avalanche deposits, 

than in lakes receiving only ash deposits and blowndown 

timber. In these lakes, increases in dissolved organic material were correlated with dense bacterial populations, and 

large increases in the concentrations of dissolved manganese, iron, and sulfur. The majority of the dissolved-organic 

material was higher molecular-weight, yellow organic acids 

similar in their general properties to aquatic fulvic acids 

found in most surface waters. Many of the specific organic 

compounds identifiable by gas chromatography mass 

spectrometry were derived from the pyrolysis of plant and 

soil organic material.

The major changes in the organic chemistry of the blastzone lakes between late summer 1980 and spring 1981 can be 

attributed to the tremendous inflow of rain and snowmelt. 

For example, the decrease in the dissolved organic carbon 

concentration of South Fork Castle Lake from 135 milligrams carbon per liter on September 11, 1980, to 10 milligrams carbon per liter on May 1, 1981, is attributable to the 

almost 14-fold increase in lake volume. Aquatic fulvic acids 

continued to be the major fraction of the organic material, 

and the refractory nature of humic substances is the major 

explanation for the persistence of the dissolved organic 

material in these lakes. During the spring and summer of 

1981, there were some changes in the chemical nature of the 

aquatic fulvic acids, such as a decrease in sulfur content. 

There appeared to be two minor sources of dissolved organic 

material in these lakes. In Spirit and South Fork Castle 

Lakes, the hypolimnion became anaerobic during the summer and the concentrations of dissolved organic carbon

increased, indicating that anaerobic decomposition of organic material in the volcanic deposits covering the lake bottoms was a small, but continuing source of dissolved organic 

material. The other minor source was dissolved organic 

material leached from volcanic ash and dead plant material. 

Many of the organic compounds identified in surface waters 

within the blast zone in the summer of 1980 were not identified in surface waters within the blast zone in the late spring 

of 1981, probably because of the considerable dilution by rain 

and snowmelt. The few compounds that were identified in the 

late spring of 1981 probably were transported into the lakes 

with rain and snowmelt that had leached volcanic debris.

INTRODUCTION

The May 18, 1980, eruption of Mount St. Helens 

in southwestern Washington caused massive and 

widespread destruction. A once-productive forest 

on the north slopes of the mountain was completely 

pyrolyzed and burned; with increasing distance 

from the mountain, trees were uprooted and stripped 

of bark, branches, needles, and leaves. In sheltered 

areas such as North Cold water Creek, many of the 

trees were blown over, burned and charred in the intense heat and then buried in the hot debris and 

mud. Still others were swept downstream in the 

mudflow before being buried. Accordingly, there 

was a significant physical, chemical, and biological 

alteration of the aquatic environments within the 

devastated blast zone.

Concentrations of many inorganic chemical constituents increased in the lakes and streams from 

the dissolution of inorganic material contained in 

the pyroclastic material, mud, ice, and ash. Additionally, because of the tremendous quantity of 

vegetation pyrolysed by the blast and eventually 

deposited in the aquatic environment, great increas1
122°37'30" 30' 22'30" 07'30" 122°00'

46°22'30"

46°07'30" - EXPLANATION Lava dome Pyroclastic- flow deposits Mudflow deposits and scoured areas Seared zone of directed blast Devastated zone of directed blast Debris-avalanche deposits 

Pre-1980 deposits

R.2E. R.3E. R.4E. R.5E.

10 MILES

I

R.6E. R.7E.

10 KILOMETERS
es occurred in the concentration of dissolved organic material. Greater concentrations of dissolved 

organic material occurred in those lakes and streams 

directly associated with pyroclastic, mudflow, and 

debris avalanche deposits, than in those water bodies into which only ash and timber were deposited 

(fig. 1). Extremely abundant microbial populations 

accompanied these increases in dissolved organic 

material and probably were caused by these increases (Wissmar, Devol, Staley, and Sedell, 1982; Baross 

and others, 1982; Staley and others, 1982).

Analysis of water samples collected from Sprit 

and Coldwater Lakes during the summer of 1980 

following the eruption showed that much of the 

dissolved organic material was similar to aquaticfulvic acids from more typical environments 

(McKnight and others, 1982). Pereira and others 

(1982) identified many specific organic compounds, 

which were similar to many of the compounds 

observed in Kraft pulp-mill wastes, thus concluding that the pyrolysis of plant and soil material in 

the blast zone was indeed the major source of 

dissolved-organic material.

In this report, data are presented that describe 

changes in the organic material in several of the 

blast-zone lakes in the summer of 1981,1 year after 

the major eruption of Mount St. Helens. Data are 

presented for: (1) The distribution of dissolved and 

suspended organic material in these lakes; (2) the 

fractionation of the dissolved-organic material into 

hydrophobic and hydrophilic solutes; (3) the characterization of aquatic humic substances; and (4) 

the identification of low molecular-weight organic 

acids and neutral-organic compounds. Determining 

the changes in the dissolved organic material is an 

important part of the overall study of the limnoligical recovery of these lakes.

DESCRIPTION OF BLAST-ZONE LAKES

Studies of the dissolved organic material in the 

summer 1980 showed that differences between lakes 

were related to differences in the way lakes had 

been physically altered by the May 18, 1980, eruption. The general physical, chemical, and biological 

characteristics of blast-zone lakes are described 

here to provide a background for discussing the 

changes in organic constituents.

FIGURE 1 (facing page). Blast zone of Mount St. Helens 

showing the dissolved organic-carbon concentrations, in 

milligrams per liter, of several lakes sampled on September 

11, 1980.

PHYSICAL CHARACTERISTICS

Lakes in the blast zone (fig. 1) can be divided into 

two major groups: (1) Those that were formed or 

directly impacted by mudflow, debris avalanche, or 

pyroclastic deposits (Spirit Lake, South Fork Castle Lake, and Coldwater Lake); and (2) those in the 

area where timber was blown down or scorched by 

the blast of hot volcanic gases, and a thick layer of 

volcanic ash was deposited (including St. Helens, 

Fawn, Hanaford, and Ryan Lakes).

South Fork Castle and Coldwater Lakes are new 

lakes that were formed by two small creeks being 

dammed by the debris avalanche and mudflow that 

filled the upper Toutle River Valley. The volume of 

water in these lakes greatly increased during the 

winter and spring of 1981. Aerial photographs of 

South Fork Castle Lake (fig. 2A, B, C, and D) 

clearly show that the lake greatly increased in size 

from November 11, 1980, to March 1, 1981. The 

volume of South Fork Castle Lake increased by 

about 14 times from 1,100 acre-feet on September 

30, 1980, to 14,960 acre-feet on May 27, 1981; and 

the volume of Coldwater Lake increased by about 6 

times from 10,800 acre-feet on October 31, 1980, to 

67,600 acre-feet on May 31, 1981 (U.S. Geological 

Survey, October 1981, unpublished data). The volume of both lakes increased more slowly through 

the summer and fall of 1981.

As shown in figure 1, pyroclastic-flow deposits 

entered and partly filled Spirit Lake during the 

May 18,1980, eruption. The areal size and elevation 

of Spirit Lake continued to increase from snowmelt 

and rainfall because the original outlet, the North 

Fork Toutle River, was blocked by the debris 

avalanche. Unlike the two newly formed lakes, there 

was a limited volume increased from 126,000 acrefeet on November 22, 1980, to 169,000 acre-feet on 

May 31, 1981.

During and after the May 18, 1980, eruption, 

trees, shrubs, and other organic debris were swept 

into Spirit, South Fork Castle, and Coldwater Lakes, 

and the lake surfaces were partly covered with 

floating logs from the summer of 1980 through the 

fall of 1981. However, the major source of dissolvedorganic material in these lakes has been pyrolyzed 

plant and soil material in volcanic deposits that 

cover the lake bottoms.

Many of the lakes in the second group in the 

timber blowdown-zone and scorch-zone also had 

large numbers of floating logs covering their surface. 

Generally, those lakes in the Mt. Margaret area 

that were covered with ice at the time of the erup-
FIGURE 2. Aerial photographs of South Fork Castle Lake on: A-July 20, 1980; B-November 11, 1980;

District Office,
C-March 1, 1981; and D-July 27, 1981. Photographs from the U.S. Geological Survey, Washington 

Tacoma, Washington.
tion (including St. Helens, Fawn, and Hanaford 

Lakes) were not as severely affected as some of the 

lakes farther away from Mt. St. Helens that were 

not covered with ice. In fact, small fir trees that 

probably had been buried by snow at the time of 

the eruption were observed along the banks of St. 

Helens Lake, which drains into Spirit Lake. By 

studying these lakes in the blown-down zone, we 

can distinguish between the effects of the mudflow, 

debris avalanche, and pyroclastic deposits, and the 

effects of the blown-down logs and the denudation 

of the watersheds.

CHEMICAL CHARACTERISTICS

INORGANIC CONSTITUENTS

The inorganic chemistry of blast-zone lakes was 

altered by dissolution of magmatic and lithic deposits (Wissmar, Devol, Nevissi, and Sedell, 1982). 

Increases in major cations, anions, and trace metals generally were greatest in the first group of 

lakes associated with mudflow, debris avalanche, 

and pyroclastic deposits, as illustrated by selected 

pre- and post-eruption data for Spirit Lake (table 1) 

obtained by Dion and Embry (1981). Similar data 

was obtained by Wissmar, Devol, Nevessi and Sedell 

(1982). The pH of these lakes remained between 6.0 

and 8.0, buffered by carbonic acid and dissolved 

organic acids.

During the winter and spring of 1981, dissolved 

inorganic constituents were diluted by rainfall and 

snowmelt. For example, the data for major cations 

and trace metals in South Fork Castle Lake on 

September 11, 1980, and on May 1, 1981, show that 

the concentration of most of these constituents 

decreased by about four fold (table 2). The volume 

of the lake increased by about 14 times during this 

interval, which indicates that dissolution of volcanic deposits in the watershed continued to be a source 

of dissolved inorganic constituents. The changes in 

the inorganic chemistry of lakes in the second group 

varied with the position of the lake relative to 

different blast deposits (Dion and Embrey, 1981; 

Wissmar, Devol, Nevissi, and Sedell, 1982).

TABLE 1. Concentrations of selected major cations, anions, 

and trace metals in Spirit Lake, March 28, 1980, and 

June 30, 1980

[Date from Dion and Embry. 1981: mg/L. milligrams per liter; jjg/L, 

micrograms per liter]

Constituent

Major cations, in mg/L,

Calcium, Ca

Magnesium, Mg

Sodium, Na

Major anions, in mg/L,

Chloride, Cl

Sulfate, SO^

Trace metals, in yig/L,

Iron, Fe

Manganese, Mn

March 28, 1980 June 6, 1980

2.8 7<t

0.6 13

2.0 68

1.5 86

1.0 190

6 5,000

10 8,800

TABLE 2. Concentrations of some major cations and trace 

metals in South Fork Castle Lake on September 11, 1980, 

and April 30, 1981

I mg/L, milligrams per liter; fjg/L, micrograms per liter]

Constituent Sept. 11, 1980 April 30, 1981

Major cations, in mg/L

Calcium, Ca 74.3 

Magnesium, Mg 16.7 

Sodium, Na 82.3

21.4

4.4

18.6

Trace metals, in yg/L

Copper, Cu

Iron, Fe

Manganese, Mn

Lead, Pb

Zinc, Zn

Strontium, Sr

28

1,970

4,570

38

38

373

14

640

1,120

33

33

97

ORGANIC CONSTITUENTS

The increase in the concentration of dissolved 

organic carbon (DOC) in blast-zone lakes has been 

discussed by Dion and Embrey (1981), Wissmar, 

Devol, Nevissi, and Sedell, (1982), Pereira and others (1982), and McKnight and others (1982). During

the summer of 1980, DOC concentrations were greatest in South Fork Castle, Coldwater and Spirit 

Lakes. For example on September 11, 1980, the 

DOC of South Fork Castle Lake was 135 mg C/L 

(milligrams carbon per liter). The DOC concentrations also were affected by the dilution of the lakes 

by snowmelt; the DOC of South Fork Castle Lake

6
on May 1,1981, was 10 mg C/L. Comparison of this 

data with the 14-fold increase in lake volume indicates that there were no major new sources of dissolved organic material in the snowmelt.

BIOLOGICAL CHARACTERISTICS

As described by Baross and others (1982), 

Wissmar, Devol, Staley, and Sedell, (1982), and 

Staley and others (1982), extensive bacterial populations and anaerobic conditions developed within 

weeks after the May 18, 1980, eruption in the most 

severely impacted lakes. Dense bacterial populations (as many as 2x107 cells per milliliter) were 

correlated with high DOC, manganese, sulfur and 

iron concentrations, as anaerobic degradation of 

organic material and oxidation of reduced metals 

were the major energy sources. Baross and others 

(1982) concluded that nitrogen-cycle reactions regulated microbial processes in these lakes.

Rain and snowmelt entering these lakes during 

the winter and spring of 1981 destratified and oxygenated these lakes (Dahm and others, 1982). 

However, as the summer progressed, the lakes 

became stratified and microbial degradation of 

organic material from volcanic deposits on the lake 

bottoms resulted in anaerobic conditions, increased 

bacterial activity, and increased concentrations of 

reduced metal species in the bottom waters.

METHODS

Samples were collected from both the epilimnion 

and hypolimnion in cleaned, precombusted glass 

bottles and stored on ice during transport to the 

U.S. Geological Survey laboratory in Lakewood, 

Colorado. Here the samples were stored at 4°C 

(degrees Celsius) until analysis. One hundred milliliters of sample were filtered through precombusted 

Gelman GFC glass fiber-filters. 1 The filtrate was 

analyzed for DOC, after acidification and purging 

of inorganic carbon dioxide, with a Beckman 915-C 

carbon analyser. The filters were frozen and subsequently analyzed for suspended organic carbon 

(SOC) by the Oceanographic Method (Strickland 

and Parsons, 1972).

The fractionation of dissolved organic material 

into hydrophobic and hydrophilic solutes was performed as described by Leenheer and Huffman

'Any use of trade names is for descriptive purposes only and does not 

constitute endorsement by the U.S. Geological Survey.

(1976) by Huffman Laboratories, Denver, Colorado. 

Aquatic fulvic acids were isolated from filtered 

(0.45 micrometer Selas silver membranes) lakewater 

samples using XAD-8 resin following the method 

described by Thurman and Malcolm (1981), with 

the exception that humic acids were not separated. 

Elemental analysis of the freeze-dried fulvic acids 

were performed by Huffman Laboratories using 

various combustive methods. Carboxylic acid and 

phenolic content was determined by potentiometric 

titration (Thurman and Malcolm, 1981). Molecular 

weight was calculated from measurement of the 

radius of gyration by small angle X-ray scattering 

(Thurman and others, 1982). Carbohydrate content 

was determined by the phenol-sulfuric acid and 

method using a 4 percent phenol solution and glucose as a standard.

The gas chromatography-mass spectrometry 

methods described by Pereira and others (1982) 

were followed without deviation. To summarize, 

unfiltered samples that had been stored at 4°C, 

were extracted with ether, to obtain neutral and 

acidic fractions. The organic-acid fraction was then 

methylated with diazomethane; and both fractions 

were analysed with a Finnigan 4000 computerized 

gas chromatograph-quadropole mass spectrometry system.

Identification of specific organic compounds 

was based on the mass spectral library fit (FIT 

values generally were about 950, with 1000 being 

a perfect fit) and more importantly on comparison 

of the relative retention time (RRT) with RRT 

values reported by Pereira and others (1982). 

Pereira and others (1982) had confirmed many of 

their organic compound identifications by analysing standard compounds and by high-resolution 

mass spectrometry.

RESULTS AND DISCUSSION

DISSOLVED AND SUSPENDED ORGANIC CARBON

Results of the DOC and SOC analyses for the 

summer of 1981 are presented in table 3 and figures 

3-6 for Spirit, South Fork Castle, Coldwater and 

St. Helens Lakes. As described previously (fig. 1), 

Spirit Lake received pyroclastic deposits; South 

Fork Castle and Coldwater Lakes were formed when 

the debris avalanche filled the North Toutle River 

Valley, and St. Helens Lake was in the zone of 

blown-down timer that received significant inputs 

of debris from the lateral blast and significant ashf all. 

The DOC concentrations in all four lakes decreased
TABLE 3. Organic carbon in four representative lakes in the blast zone of Mount St. Helens during

the summer, 1981 

(DOC, dissolved organic carbon; SOC, suspended organic carbon; mg C/L, milligrams carbon per liter.]

Date 

Lake sample 

collected

Spirit Lake 4/30

7/16

8/3

8/28

9/28

South Fork Castle 5/1

Lake 7/21

8/4

8/27

9/28

Coldwater Lake 4/30

6/17

7/16

8/5

8/27

9/27

St. Helens Lake 6/25

7/16

8/3

8/27

9/28

Epilimnion Hypolimnion

DOC SOC 

(mg C/L) (mg C/L)

17.4

14.6 0

15.2

15.3

15.0

10.2

7.7

6.2

6.7

7.4

6.9

4.0

5.3

4.7

6.0

5.6

1.5

1.7

1.6 1

1.4

1.9

«

.6

.2

.4

.5

-

.8

.4

.2

.3

-

-

.6

.60

.4

.3

.4

.5

.2

.6

.3

DOC

(mg C/L)

-

16.5

17.6

17.4

17.1

--

9.6

7.6

13.0

9.9

-

6.5

4.6

6.9

5.0

4.2

1.4

1.2

1.2

1.4

1.3

SOC 

(mg C/L)

-

2

.5

.6

.7

-

3.1

.5

1.6

-

--

.2

.60

.8

.1

.6

1.1

.8

.2

.4

.4

significantly during the winter and spring from er than in Spirit Lake before the May 18, 1980,

dilution by rain and snowmelt. For example, the eruption (0.8 mg C/L) and much greater than in

DOC concentration in Spirit Lake decreased from other lakes in the Cascade Range.

37 mg C/L on September 11, 1980, to 17 mg C/L on Sp|R|T LAKE AND SOUTH FORK CASTLE LAKE

April 30,1981; and the DOC concentration of South

Fork Castle Lake decreased from 135 mg C/L on Several trends are apparent in the data from

September 11,1980, to 10.2 mg C/L on May 1,1981. Spirit Lake and South Fork Castle Lakes (figs. 3

However, DOC concentrations in Spirit, South Fork and 4). First, DOC concentrations were much

Castle, and Coldwater Lakes were still much great- greater than SOC concentrations; these are typical
TABLE 4. Fractionation of dissolved organic carbon in surface waters in the blast zone of Mount St. Helens

|DOC, dissolved organic carbon; mg C/L, milligrams per liter.]

Lake

Spirit Lake

South Fork

Castle Lake

Coldwater

Lake

St. Helens

Lake

Ryan Lake

Fawn Lake

Hanaford

Lake

Date 

sample 

collected

9/11/80

4/30/81

7/22/81

8/31/81

9/11/80

5/1/81

7/22/81

8/31/81

9/11/80

4/30/81

7/22/81

9/11/80

7/22/81

7/22/81

9/11/80

7/22/81

9/11/80

7/22/81

Hydrophobics 

(percent)

Depth DOC 

zone (mg C/L)

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Hypolimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Hypolimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

Epilimnion

37.3

17.4

15.1

16

16.1

3.5

10.2

7.9

7.4

8.9

11.7

6.9

5.7

3.5

1.4

3.4

1.9

2.9

2.7

2.3

Acids

41

41

40

40

33

24

36

40

37

35

30

30

30

39

29

30

31

29

10

22

Neutrals

12

10

9

9

13

7

11

9

8

12

9

19

17

29

0

18

6

19

51

24

Bases

2

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

Hydrophilics 

(percent)

Acids

43

44

46

40

50

63

47

44

48

45

56

43

43

32

36

47

63

39

32

38

Neutrals

1

0

2

1

0

3

3

5

2

4

4

4

6

0

13

0

0

9

0

9

Bases

2

5

3

8

4

3

3

2

4

3

1

4

4

0

21

5

0

4

5

7

for freshwaters other than large rivers. Second, 

throughout the summer of 1981, the DOC and SOC 

concentrations generally were greater in the hypolimnia of these lakes than in the epilimnia. The 

same trend is found in the data collected by Wissmar 

and Devol (University of Washington, unpublished 

data, January 1982), and by Dahm and others 

(1982). Dahm and others (1982) also observed a 

marked increase in the DOC in the hypolimnion of 

South Fork Castle Lake in August 1981. Both of 

these lakes were aerobic in early May, but gradually became stratified with decreasing dissolvedoxygen concentrations in the hypolimnia in July 

(Dahm and others, 1982). The concentrations of 

dissolved ferrous iron and methane also increased 

in the hypolimnia from late June through August 

(Dahm and others, 1982). These data indicate that 

a major source of dissolved organic material was 

anaerobic decomposition of organic material in the 

volcanic deposits covering these lake bottoms. 

Rapid aerobic biodegradation or chemical reactions, 

such as photolysis, in the epilimnion also may 

be responsible for the lesser DOC values in the 

epilimnion.

9
18

17

16

15

14

13

| | 12

\- -i

DC DC 11 

HI

o z 10 

z o

O fO

° < 9

Z <->

m co g

sl

7

6

5

4

3

2 -

1 -

SPIRIT LAKE

DISSOLVED ORGANIC CARBON

Hypolimnion 

Epilimnion

SUSPENDED ORGANIC CARBON 

....... Hypolimnion'

 Epilimnion

JUNE

16 

JULY AUGUST SEPTEMBER

FIGURE 3. Concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of Spirit Lake

during summer 1981.

The third major trend in DOC data for Spirit and 

South Fork Castle Lakes is that the epilimnetic 

DOC concentrations did not change much in these 

lakes during the summer of 1981. As explained 

previously, the lake volumes did not increase much 

during the summer, so dilution of chemical constituents was not a major effect. For example, the volume of South Fork Castle Lake only increased 13 

percent from 14,960 acre-feet on May 27, 1981, to 

17,290 acre-feet on September 30, 1981. The constancy of the epilimnetic DOC concentrations further indicates that most of the dissolved organic 

material was in the form of relatively refractory 

substances that were not being utilized as a substrate by micro-organisms at a significant rate. 

This conclusion is further supported by data presented in the following section which shows that

the majority of the dissolved organic material could 

be characterized as humic material. The DOC concentrations in the hypolimnion of Spirit Lake also 

were stable, whereas the DOC concentrations in 

the hypolimnion of South Fork Castle Lake fluctuated significantly, increasing from 7.6 to 13 mg 

C/L during August. These fluctuations may have 

been related to temporal or spatial variations in the 

decomposition of benthic volcanic deposits in South 

Fork Castle Lake.

COLDWATER LAKE

In Coldwater Lake, DOC and SOC concentrations were not consistently greater in the hypolimnion (fig. 5) than in the epilimnion. The failure 

of dissolved organic material to accumulate in the

10
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I- W 

2 0- 

LLJ

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2 O

O m

O DC

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2 O 

O 

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CASTLE LAKE

DISSOLVED ORGANIC CARBON

 Hypolimnion

 ~ Epilimnion 

SUSPENDED ORGANIC CARBON 

....... Hypolimnionj

 Epilimnion

21

JUNE JULY

27

AUGUST

28

SEPTEMBERFIGURE 4. Concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of South Fork

Castle Lake during summer 1981.

hypolimnion probably was related to the continued 

presence of dissolved oxygen at depth until late 

August. Dahm and others (1982) concluded that 

biodegradation of organic material in the volcanic 

deposits underlying the lake probably was comparable to biodegradation in Spirit and South Fork 

Castle Lakes, based on similar rates of methane 

production. Leaching and decomposition of the logjam covering Coldwater Lake also may have contributed organic material to the surface water of 

the lake.

ST. HELENS LAKE

In St. Helens Lake (fig. 6), in the timber blowdown zone, DOC concentrations had decreased from 

3.0 mg C/L in September 1980, to about 1.5 mg 

C/L throughout the summer of 1981. These concentrations are typical of other lakes in the Cascade 

Range. For example, the DOC concentration of 

Spirit Lake during the spring before the May 18, 

1980, eruption was 0.8 mg C/L, and the DOC concentration of Merrill Lake, a small lake outside of

the blast zone 10 miles southwest of Mount St. 

Helens, was 1.0 mg C/L on May 1, 1981.

FRACTIONATION OF DISSOLVED 

ORGANIC MATERIAL

Results of the fractionation of dissolved organic 

material in blast-zone lakes in September 1980, and 

in the summer of 1981 are compared in table 4. The 

general trends indicate: (1) Hydrophobic and hydrophilic acids consistently comprise between 73 percent and 87 percent of the DOC in Spirit, South 

Fork Castle, and Coldwater Lakes; and ( 2) although 

these hydrophobic and hydrophilic acids are the 

two most important classes in the lakes in the zone 

of blown-down timber, the results are more variable, 

especially for St. Helens Lake, than in the other 

lakes. There are no obvious explanations for most 

of this variability in the data from the lakes in 

the zone of blown-down timber. The predominance 

of the organic-acid fractions has been observed 

for a wide range of surface waters (Stuber and 

Leenheer, 1978).

11
TABLE 5. Characteristics of aquatic fulvic acids isolated in samples from lakes in the blast zones of Mount St. Helens

(meq/g, millequivalents per gram; /jg/mg, micrograms per milligram; A, angstroms; C, carbon; H, hydrogen; O, oxygen; N, nitrogen; P. phosphorus;

S, sulfur; Cl. chlorine]

Lake Elemental analysis Functional groups Carbohydrate Radius of 

and contents gyration 

date (percent by weight) (meq/g) (ug/mg) A

sample collected C H O N P Ash S Cl Carboxylic acid Phenol

Spirit Lake

9/11/80 51.6 4.92 37.5 1.00 0.2 1.06 4.31 0.39 5.16 1.7

4/30/81 50.6 4.9 40.0 .36 1.8 2.35 .25 5.29 1.0

7/22/81 50.5 4.7 37.0 .63 0.32 1.93 5.8 1.2

8/31/81 50.1 4.76 36.2 .64 3.82 2.41 5.2 1.0

South Fork Castle Lake

9/11/80 51.7 4.96 37.7 .67 .2 .10 2.14 1.25 5.52 2.8

5/1/81 51.4 5.04 38.7 .54 2.6 1.09 .18 5.0 .87

7/22/81 -- 6.4 1.05

8/31/81 - - - - - - - 6.13 .93

Coldwater Lake

4/30/81 53.6 5.21 38.4 0.31 1.8 .84 .18 6.0 1.16

Merrill Lake

4/30/81 51.3 4.97 39.5 0.73 1.38 .49 .39 4.34 .83

18 10.6

64 8.7

53 7.9

57 10.8

6.5

43 10.2

71 8.7, 10.6

7/r q o

/b 7.£

53

72

In the epilimnion of Spirit Lake, the hydrophilicand hydrophobic-acid fractions were almost equal, 

and the proportion of organic material in the different fractions was remarkably constant from 

September 1980 to August 1981. This result is 

consistent with the characterization of the major 

fractions, organic acids, as refractory aquatic-humic 

substances (McKnight and others, 1982). In late 

August, a sample was analysed from the hypolimnion, where active microbial degradation of 

organic material was indicated by methane production, and by anoxic conditions below a depth of 

16 feet (Dahm and others, 1982), or a depth of 26 

feet (S.S. Embrey, October 1982, U.S. Geological 

Survey, unpublished data), and by greater DOC 

concentrations. In this sample, hydrophilic acids 

were a larger fraction than hydrophobic acids, which 

may be characteristic of the production of dissolved 

organic material from anaerobic degradation of 

organic material in the underlying volcanic deposits (McKnight and others, 1982).

In South Fork Castle Lake, DOC concentration 

was extremely high in September 1980 and the 

hydrophilic-acid fraction was much greater than 

the hydrophobic acid fraction. By early May 1981, 

after the lake volume had been greatly increased by 

oxygen-saturated rain and snowmelt, the total

organic-acid fraction had not changed much (87 

percent to 83 percent of the DOC), but the hydrophobic-acid fraction had increased in importance. 

As a result, the fractionation of organic carbon in 

Spirit Lake and South Fork Castle Lake was more 

similar in the summer of 1981 than in 1980. From 

the volume and DOC data for South Fork Castle 

Lake, we can conclude that there was approximately the same total quantity of dissolved organic 

material in the lake from September 1980 to May 

1981, which leads to a further conclusion that there 

are no major sources or losses of dissolved organic 

material during this time. If this second conclusion 

is correct, then the increased importance of the 

hydrophobic acid fraction may have been caused 

by chemical processes occurring as the lakewater 

became saturated with dissolved oxygen during 

the spring snowmelt.

In South Fork Castle Lake there was not as 

much difference between the samples from the epilimnion and the hypolimnion in August as there 

was in Spirit Lake. At one South Fork Castle Lake 

sampling site, Dahm and others (1982) found that 

there was some dissolved oxygen present in the 

hypolimnion, although the concentration was less 

than in the epilimnion. A few days later at a different site in South Fork Castle Lake, S.S. Embrey

12
10

9£sDC QC

z o

O CD

o DC 

<

z o 

o

CD CO

O £

DISSOLVED ORGANIC CARBON COLDWATER LAKE

Hypolimnion 

Epilimnion

SUSPENDED ORGANIC CARBON 

.. . . . ... Hypolimnion

 Epilimnion

17 

JUNE

16 

JULY

27 29

AUGUST SEPTEMBER

FIGURE 5. Concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of Coldwater

Lake during summer 1981.

(1982) found that the lake was oxygenated to a 

depth of 49 feet; whereas, Spirit Lake was found by 

both groups of researchers to be anoxic below a 

depth of 26 feet. The more anoxic conditions in 

Spirit Lake than in South Fork Castle Lake probably explain the greater importance of hydrophilic 

acids in the hypolimnetic waters of Spirit Lake 

than in the hypolimnetic waters of South Fork

Castle Lake.

In Coldwater Lake, the organic material also 

became more hydrophobic between September 1980 

and April 1981; however, the increase was in the 

hydrophobic-neutral fraction rather than the 

hydrophobic-acid fraction. The hydrophobic-neutral 

fraction may have been humic substances with less 

ionizable functional groups.

10

Z DC

< -1 8

°£ CE !r uj ^ °- 7

z z

O O ° OQ R6

O DC

1'

Si Ss 2

DISSOLVED ORGANIC CARBON

 Hypolimnion

 Epilimnion

SUSPENDED ORGANIC CARBON 

.... .... Hypolimnion

 Epilimnion

ST. HELENS LAKE -

25

JUNE

16 

JULY

27

AUGUST

28

SEPTEMBER

FIGURE 6. Concentration of dissolved and suspended organic carbon in the epilimnion and hypolimnion of St. Helens

Lake during summer 1981.

13
TABLE 6. Neutral organic compounds identified in a sample from South Fork Castle Lake,

on March 27, 1981

[RRT, relative retention time; FIT, mass-spectral-library fit]

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

Compound

Cycloheptane

Cyclopentanone,3-methylBenzene,ethylCyclohexanone

Benzene,( 1-methylethyl)-

Disulfide,l,l-dimethylethyl,methylTrisulfide,dimethylPhenol

7-Oxabicyclo, [2. 2.1] heptane, l-methyl-4-(l-methylethyl)-

Benzene,l-methyl-4-(-l-methylethyl)-

2-Oxabicyclo,[2.2.2]octane,l,3,3-trim ethylPhenol, 2-methoxyEthanone,l-phenylPhenol,-methyl-isomer

Bicyclo, [2. 2.1] heptane-2-one- 1, 3, 3-trimethylBicyclo [2.2. l] heptane-2-one- 1 ,7,7-trimethylPhenol,-ethyl-isomer

3-Cyclohexen-l-methanol,a,a,4-trimethylEthanone,l-(methylphenyl)-

RRT

0.21

.22

.24

.28

.33

.34

.40

.42

.47

.49

.50

.51

.55

.57

.59

.67

.72

.72

.73

FIT

950

942

973

949

929

948

978

952

990

960

995

942

976

982

963

977

973

963

966

In lakes located in the timber-blowdown zone, account for between 30 and 80 percent of the disthe concentrations of DOC were lesser than in lakes solved organic material in surface and ground

associated with the mudflow, debris-avalanche, and waters. Most aquatic humic substances can be furpyroclastic-flow deposits. As in Coldwater Lake, ther described as aquatic fulvic acids, which are

the hydrophobic-neutral fraction was an important soluble at low pH. The characterization of aquatic

fraction in the July samples from Ryan, Fawn, and humic substances from Spirit Lake and South Fork

Hanaford Lakes. However, no consistent trends Castle Lake was discussed by McKnight and othwere indicated in the comparison between Septem- ers (1982). The most unusual characteristic was

ber 1980 and July 1981. large sulfur content; for example, 4.31 percent in

	fulvic acid from Spirit Lake compared with 0.49

CHARACTERIZATION OF AQUATIC P6^ in ful fid ^ M* 11 Ll*e' There are 

HUMIC SUBSTANCES several possible chemical pathways whereby sulfur

could have been incorporated into the organic

Generally, aquatic humic substances are yellow, material, such as reaction with sulfur dioxide in the 

high molecular-weight organic acids; and they blast of volcanic gases or with dissolved hydrogen

14
TABLE 7. Neutral organic compounds identified in a sample 

from South Fork Castle Lake, May 1, 1981

[RRT, relative retention time; FIT, mass-spectral-library fit]

Compound RRT FIT

1.

2.

3.

».

5.

6.

7.

8.

Cyclopentanone,3-methylTrisulfide,dimethylBenzene,( 1-methylethyl)-

Phenol,2-methoxy2-Cyclopenten-l-one,2,3,4-trimethylEthanone, 1-phenylEthanone,l-(methylphenyl)-

l-H-inden-l-one,2,3-dihydro0.23

Al

.W

.52

.55

.56

.73

.87

920

985

935

872

972

917

983

903

sulfide in the anaerobic waters. By comparing the 

elemental-analysis data presented in table 5, the 

sulfur content in fulvic acids from both Spirit Lake 

and South Fork Castle Lake decreased by about a 

factor of 2 between September 1980 and May 1981. 

The sulfur content of the f ulvic acid in Spirit Lake 

did not change much throughout the summer of 

1981. Until the nature of the sulfur in the f ulvic acid 

has been determined, it is not possible to explain 

the decrease in sulfur content.

Other than the difference in sulfur contents, the 

elemental compositions of the aquatic fulvic acids 

in the lakes did not change during the year. Also, 

they were very similar to the elemental composition of fulvic acid from Merrill Lake, outside the 

blast zone.

There are two interesting trends in the data for 

the functional-group content of the aquatic fulvic 

acids. The first trend is that the carboxylic-acid 

contents, which are assumed to be those functional 

groups that have been titrated at pH 8, are greater 

in fulvic acids from the blast zone lakes than in 

fulvic acid from Merrill Lake, which should represent the reference aquatic fulvic acid for lakes in 

the Cascade Range. The carboxylic-acid content of 

the fulvic acid from Merrill Lake also is at the lower 

end of the range of values reported for other aquatic 

fulvic acids, between 4 and 6 meq/g (milliequivalents per gram) (Thurman and Malcolm, 1981). It 

also is interesting to note that the carboxylic-acid 

content and the carbohydrate content of the fulvic 

acid from South Fork Castle Lake was greater in 

July and in August of 1981, than in May of 1981.

The second trend is that the phenol content of 

fulvic acids from both Spirit and South Fork Castle

Lakes decreased between September 1980, when the 

lakes were completely anaerobic, and May 1981, 

when the lakes were oxygen-saturated. The decrease 

in phenol content may have resulted from phenolcondensation reactions occurring under oxygenated conditions. This hypothesis is supported by the 

significant increase in the molecular size (radius of 

gyration) of the fulvic acid from South Fork Castle 

Lake during the same period (table 5). Aerobic 

biodegradation of phenols also may explain the 

decrease in phenol content of the fulvic acids.

To summarize, the general characterization data 

show that fulvic acids from the blast-zone lakes 

were chemically changed as the lakes were aerated 

and diluted by rain and snowmelt during the winter 

and spring of 1981. However, the chemical reactions causing these changes cannot be identified 

without a more detailed structural characterization 

of the fulvic acids.

IDENTIFICATION OF ORGANIC COMPOUNDS

Organic acids and neutral organic compounds 

wer identified using gas chromatography-mass 

spec rometry by Pereira and others (1982) and 

McKnight and others (1982), in surface-water samples and volcanic-ash samples collected from the 

blast zone during the summer of 1980. Their results 

showed that the major source of organic carbon in 

the blast-zone lakes was pyrolyis of plant and soil 

organic material. They found that compounds of 

particular interest were terpenes; di-, tri-, and tetrasulfides; resin acids; and insect juvenile hormones. 

When compared with the data from the summer of 

1980, the data presented here on the organic compounds present in the blast-zone lakes 1 year after 

the May 18,1980, eruption, provide insight into the 

degradation and transport of organic material in 

surface waters of the blast zone of Mount St. Helens.

SOUTH FORK CASTLE LAKE

It was anticipated that during the snowmelt 

period the dissolved organic material in the blastzone lakes associated with mudflow, debrisavalanche and pyroclastic-flow deposits would be 

altered by dilution, oxidation, and addition of organic compounds leached from volcanic debris in the 

watershed. For this reason, samples from South 

Fork Castle Lake were analysed from the beginning (March 27,1981) and end (May 1,1981) of the 

major snowmelt period.

15
NEUTRAL ORGANIC COMPOUNDS Survey, unpublished data, January 1981) and

Several terpenes were present in South Fork Cas- Coldwater Lake (in Supplementary Data at the end

tie Lake in March 1981 (compounds 9, 11, 15, 16, of the report). The other three terpenes (compounds

and 18 in table 6). Two of the terpenes (compounds 15, 16 and 18) were found in South Fork Castle

9 and 11) were not found in South Fork Castle Lake Lake the previous summer (1980). However, no

the previous summer (1980), but were found in terpenes were found in May 1981 (table 7) at the

Coldwater Creek (W.F. Pereira, U.S. Geological end of the snowmelt; degradation under oxygenatTABLE 8. Comparison of neutral organic compounds identified in samples from South Fork Castle Lake, 

September 11, 1980, and be fore (March 27, 1981) and after (May 1, 1981) aeration and dilution by snowmelt

[x. present; -, absent]

	Sept. 11, March 27, May 1 

Compound 1980 1981 1981

1. Cycloheptane x

2. Cyclopentanone,3-methyl- x x x

3. Benzene,ethyl- x

4. Cyclohexanone - x -

5. Disulfide,l,l-dimethylethyl-, methyl- x x -

6. Trisulfide,dimethyl- - x x

7. Benzene/1-methylethyl)- x x

8. Phenol x x -

9. 7-Oxobicyclo, [2.2.1] heptane, l-methyl-4-(l-methylethyl)- - x -

10. Benzene,l-methyl-^-(l-methylethyl)- x x -

11. 2-Oxabicyclo,[2.2.2]octane,l,3,3-trimethyl- x

12. Phenol,2-methoxy- x x

13. 2-Cyclopenten-l-one,2,3,4-trimethyl- x - x

14. Ethanone,l-phenyl- x x x

15. Phenol,-methyl isomer x x -

16. Bicyclo,[2.2.l]heptane-2-one,l,3,3-trimethyl- x x -

17. Bicyclo,[2.2.1]heptane-2-one,l,7,7-trimethyl- x x -

18. Phenol,-ethyl isomer - x -

19. 3-Cyclohexen-l-methanol,a,a,4-trimethyl- x x -

20. Ethanone,l-(methylphenyl)- x x x

21. 3-Cyclohexen-l-methanol,a,a,4-trimethyl,-(5) x - -

22. 1 H-inden-l-one,2,3-dihydro- x - x

23. Phenol,5-methyl-2-(l-methylethyl)- x - -

16
TABLE 9. Organic acids identified in a sample from South Fork Castle Lake,

March 27, 1981

[RRT. relative retention time: FIT, mass-spectral-library fit]

Compound RRT FIT

1. Pentanoic acid,3-methyl,methylester 0.43 842

2. Butanedioic acid,dimethylester .56 900

3. Cyclohexanecarboxylic acid,methylester .58 987

4. Benzole acid methylester .63 990

5. Octanoic acid,methylester .64 888

6. 2-Thiabicyclo/3.1.0/Hex-3-ene-3- .65 902 

carboxylic acid,methylester

7. Hexanoic acid,methylester .67 888

8. Pentanedioic acid,methylester .69 926

9. Pentanedioic acid,3,3-dimethyl,dimethylester .76 906

10. Benzole acid,2-hydroxy-,methylester .76 989

11. Benzole acid,3-methyl,methylester .78 942

12. Heptanoic acid,methylester .80 925

13. Benzenepropanoic acid,methylester .89 987

14. Benzoic acid,3-methoxy-,methylester .96 973

15. Heptanedioic acid,dimethylester .97 984

16. Benzoic acid,-(l-methylethyl)-,methylester isomer .97 964

17. Benzoic acid,-(l-methylethyl)-,methylester isomer 1.05 973

18. Benzoic acid,3-hydroxy-,methylester 1.09 966

19. Octanedioic acid,dimethylester 1.10 996

20. Benzenedicarboxylic acid,dimethylester isomer 1.10 941

21. Benzenedicarboxylic acid,dimethylester isomer 1.16 725

22. Benzeneacetic acid,3-hydroxy,methylester 1.16 966

23. Benzenedicarboxylic acid,dimethylester isomer 1.18 976

24. Benzenepropanoic acid,4-hydroxy,methylester 1.20 874

25. Nonanedioic acid,dimethylester 1.22 994

26. 1,4-Benzenedicarboxylic acid,2-(acetyloxy)-,

dimethylester 1.29 942

27. 1,2-Benzenedicarboxylic acid,4-methyl,dimethylester 1.30 885

28. Cyclohexanecarboxylic acid,4-(l,5-dimethyl-3-oxohexyl)-

methylester isomer 1.57 984

29. Cyclohexanecarboxylic acid,4-(l,5-dimethyl-3-oxohexyl)-

methylester isomer 1.62 961

17
ed conditions or dilution by snowmelt are possible 

explanations.

Most of the phenolic compounds present in the 

summer, 1980 and early spring 1981 (compounds 8, 

12, 14, and 17 in table 6) had disappeared by May 

1981, with the exception of phenol, 2-methoxy 

(compound 4, table 7). With the development of 

oxygenated conditions, phenolic compounds would 

be involved in oxidative-coupling reactions. Additionally, aerobic biodegradation of phenols may 

have occurred. Dilution during the spring snowmelt 

also may explain the failure to detect phenolic compounds in May 1981. Phenol, 2-methoxy, a probable decomposition product of vanillin and other 

lignins, was the least abundant phenolic compound 

in March 1981, but was the only phenolic compound detected in May 1981 and its concentration 

had not decreased. This indicates a continuing input 

of phenol, 2-methoxy to South Fork Castle Lake 

during the spring snowmelt. It is important to 

emphasize that phenol, 2-methoxy, and the other 

identified compounds, represent only a small percentage (less than 1 percent) of the dissolved organic material. Therefore, the conclusion that specific 

organic compounds entered the lake with rain and 

snowmelt is consistent with the conclusion that the 

dissolved organic material, mainly aquatic fulvic 

acid and hydrophilic acids, behaved conservatively 

and that there were no major new inputs of dissolved organic material.

Several ketones were found in South Fork Castle 

Lake on all sampling dates (compounds 2, 14, and 

20 in table 8). Another ketone, 1 H-inden-1-one, 

2,3-dihydro-, which was found in volcanic ash 

(Pereira and others, 1982), was not present in March 

1981, but was present in May 1981, indicating that 

this compound entered the lake with snowmelt 

that had been in contact with volcanic ash in the 

watershed.

The changes in organic sulfide compounds are 

also interesting. Bisulfide, 1,1-dimethyl ethyl-,

TABLE 10. Organic acids identified in a sample from South

Fork Castle Lake, May 1, 1981 

[RRT, relative retention time; FIT, mass-spectral-library fit]

Compound RRT FIT

1. Benzole acid,-(l-methylethyl)-methylester isomer 1.06

2. Decanoic acid,8-methyl-,methylester

3. Heneiocsanoic acid,methylester

1.61

1.80

829

970

971

methyl was present in South Fork Castle Lake in 

September 1980 and in March 1981, but was not 

detected in May 1981, when the lake was saturated 

with dissolved oxygen. However, trisulfide, 

dimethyl- was present in March 1981 and was 

still present in May 1981, despite the oxygenated 

conditions.

ORGANIC ACIDS

The organic acids followed the same pattern as 

the terpenes and phenolic compounds: persistence 

over the winter until the end of March, and then 

disappearance by the beginning of May with the 

snowmelt runoff (1981). This is true for the fatty 

acids, dicarboxylic acids, and their derivatives 

(compounds 1, 2, 5, 7,8, 9,12,15,19, and 25 in table 

9) and for all but one of the aromatic acids (compounds 4, 10, 11,13, 14, 16,18, 20, 21, 22, 23, 24, 26, 

and 27 in table 9). The resin acids and insect juvenile hormones found in September 1980, were of 

interest because of their potential toxicity to aquatic organisms. Two of the four resin acids (compounds 

28 and 29) that had been found in the September 

sample from South Fork Castle Lake also were 

found in March, but even these compounds were 

not found in May (tables 10 and 11). From these 

data, it can be concluded that most of the change in 

the organic chemistry of South Fork Castle Lake 

was a result of dilution by snowmelt in the spring.

SPIRIT LAKE

Samples collected from Spirit Lake on August 7, 

1980, and September 11, 1980, were analysed previously (Pereira and others, 1982 and McKnight 

and others, 1982). Only a few of the compounds 

identified in the August 7, 1980, sample analysed 

by Pereira and others (1982) were found in the 

September 11,1980, sample, analysed by McKnight 

and others (1982), indicating that degradative processes already had begun in the summer of 1980. In 

this study, a sample collected on April 30, 1981, 

was analysed; the data are presented in tables 12 

and 13. In comparing the Spirit Lake data with the 

South Fork Castle Lake data, it is important to 

keep in mind that the dilution effect was much 

greater (14-fold) in South Fork Castle Lake than in 

Spirit Lake.

NEUTRAL ORGANIC COMPOUNDS

Very few of the neutral organic compounds found 

in Spirit Lake during the fall of 1980 were found in

18
April 1981 (table 12). Further, most of the neutral 

compounds found in Spirit Lake in April 1981 also 

were found in South Fork Castle Lake at the same 

time. This provides additional support for the conclusion that compounds persisting in Spirit and 

South Fork Castle Lakes in May were brought into 

the lakes with the snowmelt that had leached volcanic ash and dead plant material.

ORGANIC ACIDS

The organic acids found in Spirit Lake in April 

1981 (table 13) were predominantly: (1) Fatty acids, 

dicarboxylic acids and their derivatives (compounds 

1, 2, 5, 11, 12, and 14 in table 13) and (2) aromatic 

acids (compounds 3, 4, 6, 7, 8, 9, 10, and 13 in table 

13). Many of these organic compounds also were 

found in Spirit Lake in September 1980, and in 

volcanic ash (table 13), and could have been brought 

into Spirit Lake with snowmelt that had leached 

volcanic ash and dead plant material. The potentially toxic resin acids and insect juvenile hormones 

found in Spirit Lake in August 1980 were not found 

in September 1980 or in April 1981, which indicates 

that they probably will not re-enter the blast-zone 

lakes with the snowmelt at concentrations great 

enough to be of ecological significance.

COLDWATER LAKE

In the summer of 1980, black water containing 

large quantities of dissolved organic material was 

flowing in Coldwater Creek. Pereira (U.S. Geological Survey, unpublished data, January 1981) identified many organic compounds, including terpenes 

and resin acids in Coldwater Creek. However, in 

September 1980 the surface water of Coldwater 

Lake was not as enriched in dissolved organic carbon (15 mg C/L) as Coldwater Creek (150 mg 

C/L), and only seven neutral organic compounds 

were identified (see Supplementary Data at the end 

of the report). Four of these compounds were 

terpenes, including cineole, fenchone, and terpinen4-ol. No organic acids were identified in Coldwater 

Lake in September 1980.

NEUTRAL ORGANIC COMPOUNDS

Only three neutral organic compounds could be 

identified in the sample from Coldwater Lake collected on April 30, 1981 (table 15). These compounds were similar to compounds identified

previously in blast-zone waters. As observed in 

South Fork Castle and Spirit Lakes, terpenes did 

not persist as detectable concentrations after the 

spring snowmelt.

ORGANIC ACIDS

In contrast to September 1980 when no organic 

acids were identified in Coldwater Lake (Supplementary Data at the end of the report), many organic acids were identified in the April 30,1981, sample. 

These organic acids were mainly fatty acids, dicarboxylic acids, and their derivatives (compounds 1, 

4, 11, 13, and 14 in table 16) and aromatic acids 

(compounds 2, 3, 5, 6, 7, 8, 9, 10, and 12). As was 

true in South Fork Castle and Spirit Lake, most (10 

of 14) of the organic acids present on April 30,1981, 

in Coldwater Lake also had been found in volcanic 

ash (table 16). This again supports the conclusion 

that leaching of volcanic ash was an important 

source of low molecular-weight organic compounds 

in blast-zone lakes during the spring snowmelt.

TOUTLE AND COWLITZ RIVERS

Samples from the Toutle and Cowlitz Rivers were 

collected on June 16,1981. No neutral organic compounds which could be attributed to the effects of 

the Mount St. Helens eruption were identified in 

these samples. Dissolved organic material in surface waters draining the blast-zone area may have 

been removed in these rivers by chemical reactions, 

such as adsorption by sediments, or may have been 

decreased in concentration by dilution. The fatty 

acids and aromatic acids identified in these rivers 

(table 17) may have originated in the blast zone, 

but also may be normal organic constituents in 

these rivers. Because there is no pre-eruption data 

available for the Toutle and Cowlitz Rivers, it is not 

possible to distinguish between organic compounds 

associated with the May 18th eruption and normally 

present organic compounds. However, we can conclude that the resin acids and insect juvenile hormones that were found in blast-zone lakes in the 

summer of 1980, and which may be toxic to aquatic 

organisms, are not present in detectable concentrations in the Toutle and Cowlitz Rivers.

SUMMARY AND CONCLUSIONS

The major changes in the organic chemistry of 

the blast zone lakes between late summer 1980 and

19
TABLE 11. Comparison of organic acids identified in samples from South Fork Castle Lake and in

volcanic ash

(x, present; -, absent)

South Fork Castle Lake

Volcanic

Sept. 11, March 27, May 1, , 

Compound as

1980 1981 1981 1980

1. Butanoic acid,3-methyl-,methylester x - - -

2. Pentanoic acid,2-methyl-,methylester x - - -

3. Pentanoic acid,3-methyl-,methylester x x - -

4. Pentanoic acid,4-methyl-,methylester x

5. Benzene,methoxy- x

6. Phenol x - - -

7. Ethanedioac acid,diethylester x

8. Hexanoic acid,4-methyl-,methylester x - - -

9. Benzene, l-methoxy-4-methyl- x - - -

10. Butanedioic acid,dimethylester x - x

11. Cyclohexanecarboxylic acid,methylester x x - -

12. Penol,2-methyl- x

13. Benzoic acid,methylester x x - x

14. Phenol,2-ethyl-5-methyl- x - - -

15. Octanoic acid,methylester - x - x

16. 2-Thiabicyclo 3.1.0 hex-3-ene-3-carboxylic acid,methylester x x - -

17. Hexanoic acid,methylester x

18. Pentanedioic acid,methylester - x - -

19. Pentanedioic acid,2-methyl-,dimethylester x - - -

20. Benzeneacetic acid,methylester x - - x

21. Pentanedioic acid,3,3-dimethyl-,dimethylester - x - -

22. Benzoic acid,2-hydroxy-,methylester x x - x

23. Benzoic acid-,methyl-,methylester isomer x x - x

24. Heptanoic acid,methylester x

25. Octanoic acid,2-methyl-,methylester x - - -

26. Hexanedioic acid,dimethylester x - - x

27. Benzenepropanoic acid,methylester x x - -

28. Benzoic acid,3,5-dimethyl-,methylester x - - -

29. Benzoic acid,3-methoxy-,methylester x x - x

30. Heptanedioic acid,dimethylester x x - -

20
TABLE 11. Comparison of organic acids identified in samples from South Fork Castle Lake and in

volcanic ash Continued

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

46.

47.

48.

49.

50.

51.

52.

53.

54.

55.

South Fork Castle Lake

Sept. 11, March 27, May 1, 

Compound 

1980 1981 1981

Benzole acid,-(l-methylethyl)-,methylester isomer x x -

Benzoic acid,-(l-methylethyl)-,methylester isomer x x x

Benzoic acid,3-hydroxy-,methylester - x -

Benzoic acid,4-methoxy-,methylester x - -

Benzeneacetic acid,3-methoxy-,methylester x - -

Octanedioic acid,dimethylester x x -

1,2-Benzenedicarboxylic acid,dimethylester x x -

Benzoic acid,2,3-dimethoxy-,methylester x

Benzenepropanoic acid,-methoxy-,methylester isomer x

Benzeneacetic acid,-hydroxy-,methylester isomer x x -

Benzenedicarboxylic acid,dimethylester isomer x x -

Benzenedicarboxylic acid,dimethylester isomer x x -

Benzenepropanoic acid,-methoxy-,methylester isomer x - -

Benzenepropanoic acid,4-hydroxy-,rnethylester x

Nonanedioic acid,dimethylester x x -

Benzoic acid,3,4-dimethoxy-,methy[ester x

1,4-Benzenedicarboxylic acid,2-(acetyloxy)-,dimethylester x

1,2-Benzenedicarboxylic acid,4-methyl-,dimethylester - x -

Decanedioic acid,dimethylester x - -

Cyclohexanecarboxylic acid,4-(l,5-dimethyl~3-

oxohexyl)-,methylester isomer x x -

Cyclohexanecarboxylic acid,4-(l,5-dimethyl-3-

oxohexyl)-,methylester isomer x x -

Decanoic acid,8-methyl-,methylester x

Heneiocsanoic acid,methylester x

1-Cyclohexene-l-carboxylic acid, 4-( 1,5-

dimethyl-3-oxohexyl)-,methylester x - -

1-Phenanthrenecarboxylic acid, 1,2, 3,4, 4a, 9,10, lOaoctahydro-l,4a-dimethyl-7-(l-methylethyl)-,methylester x - -

Volcanic 

ash 

1980

x

x

-

X

-

X

X

-

-

-

X

X

-

-

X

X

-

X

-

-

-

-

X

-

X

21
TABLE 12. Neutral organic compounds identified in a TABLE 13. Organic acids identified in a sample from Spirit 

sample from Spirit Lake, April 30, 1981 Lake, April 30, 1981

[RRT, relative retention time; FIT, mass-spectral-library fit] [RRT, relative retention time; FIT, mass-spectral-library fit]

1.

2.

3.

*.

5.

6.

7.

8.

9.

Compound

Cyclopentanone,3-methylCyclopentane,l-ethyl-2-methyl,cis

Trisulfide,dimethyl2-Cyclopenten-l-one,3-methyl2-Cyclopenten-l-one,2,3,*-trimethylPhenol,2,5-dimethylEthanone,l-(methylphenyl)-

1-H-inden- l-one,2,3,-dihydrol-H-inden-l-one,2,3-dihydro-3-methylRRT

0.28

.40

.42

.42

.56

.62

.7*

.87

.92

FIT

949

942

937

917

971

919

991

972

941

spring 1981 can be attributed to the tremendous 

inflow of rain and snowmelt to these lakes. For 

example, the volume of South Fork Castle Lake 

increased about 14 times during the same period 

that the DOC concentration decreased from 135 to 

10 mg C/L. The apparent conservative nature of 

DOC in these lakes is explained by the fact that 

most of the DOC was aquatic fulvic acids, which 

are generally thought of as refractory end products 

of organic-material degradation.

Another important observation was that during 

the summer of 1981, the DOC concentrations were 

greater in the hypolimnion than in the epilimnion 

for Spirit Lake and South Fork Castle Lake, where 

hypolimnetic anoxic conditions developed from the 

decomposition of organic material in the lakebottom volcanic deposits. This observation indicates that the anaerobic degradation of lake-bottom 

organic material is a source of dissolved organic 

material in these lakes. In Spirit Lake, where anoxic conditions were most severe, hydrophilic acids 

were more important than fulvic acids in hypolimnetic waters, whereas aquatic fulvic acids were 

the most important fraction in samples from the

1.

2.

3.

*.

5.

6.

7.

8.

9.

10.

11.

12.

13.

It.

Compound

Butanedioic acid,dimethylester

Butanedioic acid, -methyl-, dimethylester

Benzoic acid,methylester

Benzole acid,-methyl-,methylester isomer

Hexanedioic acid,dimethylester

Benzoic acid,-dimethyl-,methylester isomer

Benzoic acid,-(l-methylethyl)-,methylester isomer

Benzoic acid,-(l-methylethyl)-,methylester isomer

1,2-Benzenedicarboxylic acid.dimethylester

1,3-Benzenedicarboxylic acid,dimethylester

Dodecanoic acid,methylester

Nonanedioic acid,dimethylester

Benzoic acid,3,*-dimethoxy-,methylester

Heneicosanoic acid,methylester

RRT

0.5*

.58

.63

.80

.8*

.93

.95

1.07

1.12

1.17

1.20

1.23

1.28

2.82

FIT

990

768

936

79*

810

759

717

9*7

986

917

899

727

769

88*

oxygenated epilimnion of Spirit Lake and from 

other lakes.

One of the unique characteristics of aquatic fulvic 

acids isolated from Spirit Lake and South Fork 

Castle Lake in the summer of 1980 was very high 

sulfur content: 4.31 percent by weight in Spirit 

Lake, and 2.14 percent in South Fork Castle Lake. 

In the spring and summer of 1981, the sulfur contents of the aquatic fulvic acids continued to be 

moderately high compared to other aquatic fulvic 

acids, but had decreased by about a factor of 2 to 

2.35 percent in Spirit Lake fulvic acid and 1.09 

percent in South Fork Castle Lake fulvic acid. Characterization of the chemical form of sulfur in these 

aquatic-fulvic acids may provide insight into interactions between sulfur and dissolved organic matter in aquatic environments.

In South Fork Castle Lake, many of the organic 

compounds found in September 1980 including 

terpenes, resin acids, and phenolic compounds, per22
TABLE 14. Organicacids identified in samples from Spirit Lake, Septemberll, 1980, andAprilSO, 1981,

and in volcanic ash

[x, present; -, absent)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

1*.

15.

16.

17.

18.

20.

Compound

Butanedioic acid,dimethylester

Butanedioic acid,-methyl-,dimethylester

Benzole acid,methylester

Pentanedioic acid,2-methyl-,dimethylester

Benzole acid,-methyl-,methylester isomer

Hexaneodioic acid,dimethylester

Benzole acid,-dimethyl-,methylester isomer

Benzole acid,-(l-methylethyl)-,methylester isomer

Benzole acid, 3-methoxy-, met hylester

Benzole acid,-(l-methylethyl)-,methylester isomer

1,2-Benzenedicarboxylic acid,dimethylester

Benzole acid,4-methoxy-,methylester

Benzole acid,3,4-dichloro-,methylester

1,3-Benzenedicarboxylic acid,dimethylester

Dodecanoic acid,methylester

Nonanedioic acid,dimethylester

Benzole acid,3,4-dimethoxy-,methylester

Benzenepropanoic acid,-methoxy-,methylester isomer

Heneicosanoic acid,methylester

Spirit Lake

Septemberll April 30 Volcanic ash 

1980 1981 1980

XXX

XXXXX

X - -

XXX

XXX

- X -

XXX - X

XXX X

X - X

X - X

XXXXX

X X

XXX

X - -

- X X
TABLE 15. Neutral organic compounds identified in a

sample from Coldwater Lake, April 30, 1981 

(RRT. relative retention time; FIT. mass-spectral-library fit]

Compound

1. Cyclopentane,l-ethyl-3-methyl2. Disulfide,bis( 1,1-dimethylethyl)-

3. 2-cyclohexen-l-one,4-ethyl-3,Wimethylsisted in the lake at detectable concentrations until 

March 27, 1981, but were not detectable by May 1, 

1981. Most of the organic compounds found in 

April 1981 in the blast-zone lakes (Spirit, South 

Fork Castle, and Coldwater Lakes) were fatty acids, 

dicarboxylic acids, and aromatic acids that had 

also been found in volcanic ash. The conclusion is 

reached that leaching by rain and snowmelt of the 

large quantities of volcanic ash deposited in the 

watersheds was a significant source of low molecularweight organic compounds. Since the low molecular weight organic compounds were only a small 

percentage of the dissolved organic material, this 

conclusion is consistent with the other conclusion 

that the dissolved organic material behaved conservatively and that there were no major new sources 

of dissolved organic material. Only a few fatty 

acids and aromatic acids were identified in samples 

from the Toutle and Cowlitz Rivers, and without 

pre-eruption data, it is not known whether these 

organic acids are associated with the effects of the 

May 18 eruption of Mount St. Helens.

TABLE 16. Organic acids identified in a sample from Coldwater Lake, April 30, 1981, and comparison

with organic material in volcanic ash 

[RRT, relative retention time; FIT, mass-spectral-library fit; x. present; -, absent]

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

Compound

Butanedioic acid, dim ethylester

Benzole acid,methylester

Benzole acid,3-methyl-,methylester

Hexanedioic acid,dimethylester

Benzole acid,3,5-dimethyl-,methylester

Benzole acid,-(l-methylethyl)-,methylester isomer

Benzole acid,-(l-methylethyl)-,methylester isomer

1,2-Benzenedicarboxylic acid, dim ethylester

Benzenedicarboxylic acid,dimethylester isomer

Benzenedicarboxylic acid,dimethylester isomer

Nonanedioic acid,dimethylester

Benzole acid,3,4-dimethoxy-,methylester

Decanoic acid,8-methyl-,methylester

Heneicosanioc acid,methylester

RRT

0.55

.61

.78

.83

.89

1.02

1.06

1.07

1.11

1.18

1.22

1.27

1.71

1.80

FIT Volcanic ash

954

960

812

888

826

951

975

961

998

924

977

893

935

970

X

X

X

X

-

-

-

X

X

X

X

X

-

X

24
TABLE 17. Organic acids identified in samples from the Toutle and Cowlitz Rivers, and in volcanic ash

|RRT, relative retention time; FIT, mass-spectral-library fit; x, present; -. absent]

Compound RRT FIT Volcanic ash

	Toutle River

1. Benzoic acid,methylester

2. Benzoic acid,3-methoxy-,methylester

3. 1,2-Benzenedicarboxylic acid,dimethylester

4. Benzenedicarboxylic acid,dimethylester isomer

5. Benzenedicarboxylic acid,dimethylester isomer

6. Nonanedioic acid,dimethylester

0.62

1.00

1.11

1.16

1.17

1.21

949

852

928

902

950

924

Cowlitz River

1. Butanedioic acid,dimethylester

2. 1,2-Benzenedicarboxylic acid,dimethylester

3. Benzenedicarboxylic acid,dimethylester isomer

4. Heneicosanoic acid,methylester

0.56

1.11

1.17

1.79

892

791

877

912

REFERENCES CITED

Baross, J.A., Dahm, C.N., Ward, A.K., Lilley, M.D., and 

Sedell, J.R., 1982, Initial microbiological response in 

lakes to the Mt. St. Helens eruption: Nature, v. 296, 

p. 49-52.

Dahm, C.M., Baross, J.A., Lilley, M.D., Ward, A.K., and 

Sedell. J.R., 1982, Lakes in the blast zone of Mt. St. 

Helens Chemical and microbial responses following 

the May 18, 1980 eruption, in Funk, W.H., ed., Conference on Mt. St. Helens Effects on water resources: 

Pullman, Washington.

Dion, N.P., and Embrey, S.S., 1981, Effects of Mount St. 

Helens eruption on selected lakes in Washington: U.S. 

Geological Survey Circular 850-G, 25p.

Embrey, S.S., 1982, Unpublished data on file at the U.S. 

Geological Survey, Tacoma, Washington, October 1982.

Leenheer, J.A., and Huffman, F.W.D., Jr., 1976, Classification or organic solutes in water by using macroreticular resins: U.S. Geological Survey, Journal of 

Research, v. 4, p. 737-751.

McKnight, D.M., Pereira, W.E., Ceazan, M.L., and Wissmar, 

R.C., 1982, Characterization of dissolved organic 

material in surface waters within the blast zone of 

Mount St. Helens, Washington: Organic Geochemistry, 

v. 4, p. 85-92.

Pereira, W.E., 1981, Unpublished data on file at the U.S. 

Geological Survey, Denver, Colorado, January 1981.

Pereira, W.E., Rostad, C.E., Taylor, H.E.,and Klein, J.M., 

1982, Characterization of organic contaminants in environmental samples associated with Mount St. Helens 

1980 volcanic eruption: Environmental Science and 

Technology, v. 16, p. 387-395.

Staley, J.T., Lehmicke, L.G., Palmer, F.E., Peet, R.W., 

and Wissmar, R.C., 1982, Impact of Mount St. Helens 

eruption on bacteriology of lakes in the blast zone: 

Applied and Environmental Microbiology, v. 4, p. 

664-670.

Strickland, J.D.H., and Parsons, T.R., 1982, A practical 

handbook of seawater analysis: Fisheries Research 

Board of Canada, Bulletin 167, p. 153-159.

Stuber, H.A., and Leenheer, J.A., 1978, Assessment of a 

resin based fractionation procedure for monitoring 

organic solutes from oil shale retorting wastes, in 

Everett, L.G., and Schmidt, K.D., eds., Establishment 

of Water Quality Monitoring Programs: American 

Water Resources Association, p. 266-272.

Thurman, E.M., and Malcolm, R.L., 1981, Preparative isolation of aquatic humic substances: Environmental 

Science and Technology, v. 15, p. 463-466.

Thurman, E.M., and Malcolm, R.L., 1983, Structural study 

of humic substances: new approaches and methods, 

in Christman, R.F., and Giessing, E.T., eds., Aquatic 

and Terrestrial Humic Materials: Ann Arbor, p. 1-23.

25
Thurman, E.M., Malcolm, R.L., and Aiken, G.R., 1978, 

Prediction of capacity factors for aqueous organic 

solutes adsorbed on a porous acrylic resin: Analytical 

Chemistry, v. 50, p. 775-779.

Thurman, E.M., Wershaw, R.L., Malcolm, R.L., and 

Pinckney, D.J., 1982, Molecular size of aquatic humic 

substances: Organic Geochemistry, v. 4, p. 27-35.

U.S. Geological Survey, 1981, Unpublished data on file at 

the U.S. Geological Survey, Tacoma, Washington, 

October 1981.

Wissmar, R.C., Devol, A.H., Nevissi, A.E., and Sedell, 

J.R., 1982, Chemical changes of lakes within the Mount 

St. Helens blast zone: Science, v. 216, p. 175-178.

Wissmar, R.C., Devol, A.M., Staley, J.T., and Sedell, J.R., 

1982, Biological responses of lakes in the Mount St. 

Helens blast zone: Science, v. 216, p. 178-181.

Wissmar, R.C., and Devol, A.H., 1982, Unpublished data on 

file at the University of Washington, Seattle, Washington, January 1982.

SUPPLEMENTARY DATA

On September 7, 1980, water samples were collected from several lakes and surface waters in the 

blast zone of Mount St. Helens and the dissolved 

organic material was characterized. Most of the 

results are discussed in McKnight and others (1982). 

This supplementary data section presents the organic compounds identified in five lakes in the ashfall 

and timber-blowndown area that had lesser DOC 

concentrations than Spirit Lake and South Fork 

Castle Lake. In Coldwater Lake several terpenes 

were identified (compounds 1, 2, 4, and 5); in the 

other four lakes, only one or two compounds were 

identified (table 18). These data are important for 

comparison with data from other lakes more severely impacted by the May 18,1980, eruption of Mount 

St. Helens.

TABLE 18. Neutral organic compounds and organic acids 

identified in samples from several lakes in the blast zone 

of Mount St. Helens

[RRT, relative retention time, FIT, mass-spectral-library fit]

Compound

Coldwater Lake

1. 7-Oxabicyclo, 2.2.1

heptane, l-methyl-4-( 1-methylethyl)-

2. 2-Oxabicyclo, 2.2.2 

octane, 1,3,3-trimethyl- 

(cineole)

3. Ethanone, 1-phenyl4. Bicyclo, 2.2.1 heptane-2-one-1,2,2- 

trimethyl- 

(fenchone)

5. 3-Cyclohexen-l-ol,4-methyl-l- 

(1-methylethyl)- 

(terpinen-4-ol)

6. Ethanone,l-(methylphenyl)-

7. Phenol,5-methyl-2-(l-methylethyl)-

St. Helens Lake 

1. Disulfide,bis(l,l-dimethylethyl)-

Hanaford Lake 

1. Cyclohexane,( 1,1-dimethylethyl)-

Ryan Lake

1. Butanedioic acid,dimethylester

2. Benzole acid,chloro-,methylester isomer

Fawn Lake 

1. Cyclohexane( 1,1-dimethylethyl)-

RRT FIT

.54 

.59

.62

965

975

911

.75 908

.76 984

.90 903

.67 895

.39 945

.54 989

.87 923

.39 941

U.S. GOVERNMENT PRINTING OFFICE: 1984 - 576-049/20,004

26