Radioisotopic Data of Sediment Collected in Mobile and 

Bon Secour Bays, Alabama 

By Marci E. Marot and Christopher G. Smith 

Open-File Report 2012-1172

U.S. Department of the Interior 

U.S. Geological Survey 
ii

U.S. Department of the Interior 

KEN SALAZAR, Secretary 

U.S. Geological Survey 

Marcia K. McNutt, Director 

U.S. Geological Survey, Reston, Virginia: 2012 

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Suggested citation: 

Marot, M.E., and Smith, C.G., 2012, Radioisotopic data of sediment collected in Mobile and Bon Secour Bays, 

Alabama: U.S. Geological Survey Open-File Report 2012-1172, 15 p. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report. 

Front photographs: C. Smith and A. Atchinson collecting box cores onboard the R/V G.K. Gilbert; Gamma 

spectroscopy system, USGS, St. Petersburg, FL; Alpha spectroscopy system USGS, St. Petersburg, FL. 
iii

Contents 

Introduction .................................................................................................................................................................... 1

Data Collection and Processing ..................................................................................................................................... 2

Collection and Processing of Box Cores ................................................................................................................. 2

Gamma Spectroscopy Analyses ............................................................................................................................. 2 

Alpha Spectroscopy Analyses ................................................................................................................................. 3 

Results and Discussion ................................................................................................................................................. 3 

Acknowledgments ......................................................................................................................................................... 5

References Cited ........................................................................................................................................................... 5

Figures 

1. Site locations in Mobile and Bon Secour Bays, Alabama. ................................................................................... 7

Tables 

1. Site location, Mobile Bay, Alabama...................................................................................................8

2. Physical and radioisotopic data for Mobile Bay core MB0810-2BC.......................................................... 9 

3. Physical and radioisotopic data for Mobile Bay core MB0810-4BC..........................................................10

4. Physical and radioisotopic data for Mobile Bay core MB0810-5BC..........................................................11 

5. Physical and radioisotopic data for Mobile Bay core MB0810-7BC..........................................................12 

6. Physical and radioisotopic data for Mobile Bay core MB0810-8BC......................................................... 13 

7. Physical and radioisotopic data for Mobile Bay core MB0810-12BC....................................................... 14 

8. Physical and radioisotopic data for Mobile Bay core MB0810-20BC....................................................... 15 
iv

Conversion Factors 

SI to Inch/Pound 

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

Volume

milliliter (mL) 0.03382 ounce, fluid (fl. oz)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

Density

gram per cubic centimeter (g/cm3) 62.4220 pound per cubic foot (lb/ft3) 

Radioactivity

disintegration per minute (dpm) 0.45 picocurie (pCi) 

Energy

kiloelectronvolt (keV) 1.60 E-16 Joule (J) 
1

Radioisotopic Data of Sediment Collected in Mobile and 

Bon Secour Bays, Alabama 

 By Marci E. Marot and Christopher G. Smith 

Introduction 

The focus of this study was to determine the extent of natural and (or) anthropogenic impacts on 

the sedimentary records of Mobile and Bon Secour Bays, Alabama during the last 150 years (fig. 1). 

These bays are unique in that anthropogenic activities are generally widespread and span both the 

eastern and western shorelines. However, there is a clear distinction in the types of human development 

and infrastructure between the western and eastern shorelines. These activities and the differences in 

land-use and -change influence the overall supply and remobilization of sediment to and within the bay. 

These factors could subsequently threaten the health and integrity of these environments and their 

ability to mitigate against long-term processes associated with climate change. In an attempt to 

characterize long-term accretion rates within the Mobile Bay Estuarine System (MBES), seven box 

cores were collected (fig. 1) and analyzed for excess lead-210 (210Pbxs, the difference between total and 

supported 210Pb) and cesium-137 (137Cs) activities. The MBES receives sediment and water from the 

Alabama and Tombigbee River watersheds, which converge into the Mobile-Tensaw River (MTR) 

system just prior to discharging into Mobile Bay. Riverine discharge from the MTR system to the bay is 

second only to the Mississippi River discharge to the Gulf of Mexico for the conterminous United 

States. 
2

Data Collection and Processing 

Collection and processing of box cores 

During an August 2010 research cruise aboard the U.S. Geological Survey (USGS) RV G.K. 

Gilbert, box cores were also collected from several stations (table 1; fig. 1) using a modified Wildcotype box corer. After placing the box corer on deck, a 6-inch plastic core liner was inserted into the box 

core, and the subcore was carefully extracted to preserve the sediment-water interface. The sediment 

cores were refrigerated after collection to minimize dissolution of the foraminifera tests (see K.A. 

Richwine and L.E. Osterman, in press) and were subsequently extruded and sampled at 1-centimeter 

(cm) intervals within 48 hours (h) after collection. The sediment samples were refrigerated and 

transported to the USGS in St. Petersburg, Florida. The samples remained refrigerated until lab 

processing. 

A split of each 1-cm subsample was processed for basic sediment characteristics (dry bulk 

density and mass-water content) and geochronology via excess lead-210 (210Pbxs,) and 137Cs. Masswater content and bulk density were determined by drying 30 milliliters (mL) of wet sediment at 60 

degrees Celcius (oC). Differences in the pre- and post-drying masses were used to compute water 

content; dry bulk density was computed as the ratio of dry sediment to initial volume (30 mL). Organic 

matter content was determined using standard loss-on-ignition (LOI); 5 to 10 grams (g) of dried 

sediment were baked at 450oC for 6 h. Pre- and post-baking masses were used to compute a percent 

LOI. 

Gamma Spectroscopy Analyses 

An additional split of each subsample was processed for the determination of 210Pbxs and 137Cs 

by standard gamma-ray spectrometry. Each subsample (approximately 80 g of wet sediment) was 
3

freeze dried and subsequently homogenized using a mortar and pestle. Between 15 and 20 g of dried 

sediment was sealed in air-tight plastic containers for approximately 4 weeks prior to measurement to 

achieve secular equilibrium between radon-222 (222Rn) and its parent radium-226 (226Ra). Each sample 

was counted for a 2- to 3-day period on a planar-style, low-energy, high-purity germanium, gamma-ray 

spectrometer (Canberra, Inc.). Total 210Pb and 137Cs were determined using photopeaks 46.5 and 661.6 

kiloelectron-volts (keV), respectively. Supported 210Pb (produced from sediment-bound 226Ra) was 

estimated using the 295.1 and 352.1 keV photopeaks for 214Pb and the 609.3 keV photopeak for 

bismuth-214 (

214Bi). Sample count rates were corrected for detector efficiency (referenced to the 

International Atomic Energy Agency RGU-1 standard), standard photopeak-intensity, and selfabsorption corrections using a 238U sealed source (Cutshall and others, 1983). The reported activities 

were decay corrected to the date of sample collection. The statistical counting error for each 

radioisotope is reported. The critical level (Lc) (McCurdy and others, 2008) is reported for each 

radioisotope. The Lc is the threshold value above which the radioisotope is considered to be detected. 

Radioisotopic activities were also determined for thorium-234 (234Th, 63.3 keV photopeak) and 

potassium-40 (40K, 1460.8 keV photopeak). 

Alpha Spectroscopy Analyses 

 A split was taken of each subsample for the determination of 210Pbtotal by standard alpha 

spectrometry (Robbins and Edgington, 1975; Swarzenski and others, 2006). Total 210Pb (210Pbtot = 

210Pbsup + 210Pbxs) was determined by alpha spectroscopy following the procedure of Robbins and 

Edgington (1975) and Swarzenski and others (2006). Total 210Pb activity was determined by measuring 

its daughter isotope, polonium-210 (210Po), which is assumed to be in secular equilibrium with its 

parent. Approximately 5 g of sediment was spiked with 1 mL of 209Po of known activity (2.70

picocuries per milliliter). Sediments were leached with a combination of concentrated nitric and 
4

hydrochloric acid with the addition of 30 percent hydrogen peroxide to remove organics. Sediment was 

taken to near dryness and re-saturated three times with hydrochloric acid until all nitric acid was 

removed. 209,210Po were electroplated onto silver planchets and counted on an Ortec 576A alpha 

spectrometer. Count rate efficiency for 209Po was determined and applied to 210Po counts. 

Results and Discussion 

Basic physical (wet and dry bulk density, water content, and loss-on-ignition) and 

radioanalytical data for the seven box-core sediments are presented in tables 2 – 8. The physical 

characteristics of the sediment show a generally fine-upward pattern for much of the bay, with water 

content and organic matter content increasing upcore and bulk density decreasing upcore (tables 2 – 8). 

Exception to the generalization is observed at MB0810-2BC and -5BC, which lie at the outer edge of 

the bayhead delta (foredelta). Excess 210Pb varied considerably across the entire bay. Surface activities 

vary from 1.18 to 3.24 pCi g

-1 and increase away from the bayhead delta. Excess 210Pb observed at 

depth in the sediments also varies between 21 cm (MB0810-5BC) and 45 cm (MB0810-2BC). With the 

exception of the most marine-influenced site (MB0810-8BC), average surface 210Pb activities 

(2.09±0.59 pCi g-1) are within error to those observed in local marshes (1.57±0.50 pCi g-1; C.G. Smith,

in press, 2012). In contrast, MB0810-8BC at the bay-gulf inlet has twice the surface activity,

suggesting potential focusing from the marine and(or) estuarine system. All of the cores contain 

quantifiable 137Cs; however, the overall preservation of the typical step (dirac delta) function 

representative of the mid-20th -century test period is not well defined. Instead, 137Cs is distributed 

uniformly to variable depths (8 – 33 cm) within the cores, indicating possible post-depositional mixing. 

For most cores, the vertical distribution of 234Th and 40K is fairly uniform (relative standard deviation 

(RSD) less than 10 percent of the mean). The exceptions are MB0810-8BC and -20BC; 234Th increases 

at depth in each core. The range in vertically averaged 234Th activities is 1.03 to 1.60 pCi g-1 and 
5

decreases along the axis of the bay. This trend holds whether MB08010-8BC and -20BC are included 

or excluded. In comparison, all cores that have RSD of vertically averaged 40K are all less than 10 

percent. Vertically averaged 40K values are also gradational, with activities decreasing from 12.99 pCi 

g

-1 at the head of the bay (MB0810-2BC) to 10.45 pCi g-1 (average of MB0810-7BC and -8BC) at the 

foot of the bay. This spatial variability in both 234Th and 40K may reflect a change in sediment source or 

composition, the prevailing salinity gradient within the bay, and (or) diagenetic variability within the 

sediment column. 

Acknowledgments 

The authors wish to thank Caitlin Reynolds (USGS) and Andrew Atchinson (Eckerd College) for help 

with field sampling, and Tim Dellapenna (Texas A&M Univeristy-Galveston) for graciously allowing 

the use of the box corer. Assistance in sample processing and data management was provided by Adis 

Muslic, Tom Harmon, Joseph “Donny” Smoak (University of South Florida-St. Petersburg), and Lisa 

Osterman (USGS). 

References Cited 

Cutshall, N.H., Larsen, I.L., Olsen, C.R., 1983, Direct analysis of 210Pb in sediment samples: Self 

absorption corrections: Nuclear Instruments and Methods, v.206, p.309-312.

McCurdy, D.E., Garbarino, J.R., and Mullin, A.H., 2008, Interpreting and reporting radiological 

water-quality data: U.S. Geological Survey Techniques and Methods, book 5, chap. B6, 33 p. 

Richwine, K.A., and Osterman, L.E., 2012, Benthic foraminiferal census data from Mobile Bay, AL - 

Counts of surface samples and box cores: U.S. Geological Survey Data Series 704, available 

only online at http://pubs.usgs.gov/ds/704/.

Robbins, J.A., and Edgington, D.N., 1975, Determination of recent sedimentation rates in Lake 
6

Michigan using Pb-210 and Cs-137: Geochimica et Cosmochimica Acta, v.39 no.3, p.285-304.

Smith, C.G., Osterman, L.E., Poore, R.Z., in press, An examination of historic inorganic 

sedimentation and organic matter accumulation in several marsh types within the Mobile Bay 

and Mobile-Tensaw River Delta region. Journal of Coastal Research. 

Swarzenski, P., Baskaran, M., Rosenbauer, R. and Orem, W., 2006, Historical trace element distribution 

in sediments from the Mississippi River Delta: Estuaries and Coasts, v.29 no.6, p.1094-1107.
7

Figure 1. Site locations in Mobile and Bon Secour Bays, Alabama. 
8

Table 1. Site Location, Mobile and Bon Secour Bays, Alabama.

[dd, decimal degrees; CDT, Cental Daylight Time; m, meter; °C, degrees Celsius; salinity, practical salinity 

unit; --, not measured] 

Sample ID Latitude 

(dd)

Longitude 

(dd)

Date/Time 

(CDT)

Water 

Depth 

(m)

Temperature 

(°C) Salinity

MB0810-2BC 30.59440 87.98105 8/6/10 10:45 3.7 30.66 8.09

MB0810-4BC 30.43943 87.98302 8/6/10 15:25 3.8 30.35 16.43

MB0810-5BC 30.42261 88.05108 8/6/10 16:08 3.8 30.48 16.49

MB0810-7BC 30.27719 88.06123 8/5/10 14:00 4.9 28.73 21.36

MB0810-8BC 30.26765 87.98110 8/5/10 15:30 4.1 29.30 22.74

MB0810-12BC 30.35144 88.08526 8/5/10 13:30 3.8 30.80 17.52

MB0810-20BC 30.29100 87.88300 8/5/10 8:45 -- 31.03 16.45
9

Table 2. Physical and radioisotopic data for Mobile Bay core MB0810-2BC.

Depth 

(cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.23 0.55 0.55 9.01 1.18 +/- 0.09 ND 1.99 +/- 0.17 0.94 +/- 0.06 1.65 +/- 0.19 12.46 +/- 0.91

1-2 1.23 0.57 0.53 7.81 1.39 +/- 0.01 ND 2.20 +/- 0.17 1.04 +/- 0.05 1.39 +/- 0.16 12.53 +/- 0.85

2-3 1.21 0.55 0.55 8.35 1.58 +/- 0.02 0.10 +/- 0.02 2.22 +/- 0.13 0.99 +/- 0.04 1.43 +/- 0.13 12.44 +/- 0.65

3-4 1.19 0.50 0.58 8.93 1.45 +/- 0.02 0.08 +/- 0.03 2.19 +/- 0.17 0.99 +/- 0.05 1.53 +/- 0.19 12.07 +/- 0.83

4-5 1.20 0.56 0.54 9.08 1.57 +/- 0.14 0.10 +/- 0.03 2.14 +/- 0.14 0.98 +/- 0.05 1.51 +/- 0.15 13.42 +/- 0.76

5-6 1.14 0.47 0.59 8.62 1.39 +/- 0.06 0.08 +/- 0.03 2.28 +/- 0.17 0.96 +/- 0.05 1.42 +/- 0.18 12.95 +/- 0.83

5-6c

8.67 1.50 +/- 0.02

6-7 1.17 0.47 0.59 8.84 1.45 +/- 0.11 0.11 +/- 0.03 2.35 +/- 0.18 1.01 +/- 0.06 1.52 +/- 0.19 12.57 +/- 0.86

7-8 1.19 0.49 0.59 8.36 1.47 +/- 0.04 0.09 +/- 0.02 2.01 +/- 0.15 0.88 +/- 0.05 1.30 +/- 0.16 11.96 +/- 0.73

8-9 1.19 0.51 0.58 7.13 1.48 +/- 0.02 0.10 +/- 0.02 2.25 +/- 0.15 0.91 +/- 0.04 1.42 +/- 0.15 12.95 +/- 0.73

9-10 1.16 0.49 0.58 8.39 1.40 +/- 0.02 0.09 +/- 0.02 1.94 +/- 0.12 0.92 +/- 0.04 1.54 +/- 0.13 11.71 +/- 0.61

10-11 1.19 0.53 0.55 8.85 1.57 +/- 0.10 0.10 +/- 0.03 2.17 +/- 0.17 0.90 +/- 0.05 1.40 +/- 0.17 12.59 +/- 0.85

11-12 1.15 0.48 0.58 8.75 1.51 +/- 0.13 0.11 +/- 0.03 2.20 +/- 0.17 0.91 +/- 0.05 1.32 +/- 0.18 12.80 +/- 0.89

11-12c

8.49 1.43 +/- 0.04

12-13 1.15 0.47 0.59 8.51 1.57 +/- 0.14 0.10 +/- 0.02 2.41 +/- 0.13 0.90 +/- 0.04 1.55 +/- 0.14 12.74 +/- 0.63

13-14 1.22 0.55 0.55 7.90 1.55 +/- 0.21 0.07 +/- 0.02 1.92 +/- 0.14 0.78 +/- 0.04 1.30 +/- 0.15 10.62 +/- 0.68

14-15 1.16 0.49 0.58 8.31 1.55 +/- 0.01 0.09 +/- 0.02 2.06 +/- 0.14 0.94 +/- 0.04 1.39 +/- 0.15 11.75 +/- 0.69

15-16 1.17 0.48 0.59 8.47 1.57 +/- 0.20 0.11 +/- 0.03 2.19 +/- 0.15 0.94 +/- 0.05 1.41 +/- 0.15 12.65 +/- 0.73

16-17 1.18 0.51 0.56 7.86 1.41 +/- 0.10 0.08 +/- 0.02 2.01 +/- 0.13 0.86 +/- 0.04 1.61 +/- 0.13 12.20 +/- 0.62

17-18 1.27 0.64 0.49 7.54 1.25 +/- 0.10 0.08 +/- 0.03 2.03 +/- 0.17 1.01 +/- 0.05 1.63 +/- 0.19 12.11 +/- 0.85

17-18c

7.04 1.24 +/- 0.12

18-19 1.18 0.54 0.54 6.50 1.19 +/- 0.20 0.09 +/- 0.03 1.91 +/- 0.14 0.97 +/- 0.05 1.54 +/- 0.15 12.52 +/- 0.74

19-20 1.23 0.61 0.51 5.84 0.99 +/- 0.13 0.07 +/- 0.03 1.90 +/- 0.15 0.97 +/- 0.05 1.69 +/- 0.20 11.69 +/- 0.82

20-21 1.30 0.67 0.48 5.79 1.03 +/- 0.04 0.10 +/- 0.03 1.87 +/- 0.17 1.09 +/- 0.06 1.47 +/- 0.19 13.93 +/- 0.90

21-22 1.27 0.67 0.47 7.03 0.90 +/- 0.06 0.06 +/- 0.03 1.86 +/- 0.15 1.09 +/- 0.05 1.74 +/- 0.18 12.71 +/- 0.76

22-23 1.30 0.70 0.47 6.49 0.87 +/- 0.05 0.12 +/- 0.03 1.58 +/- 0.16 1.09 +/- 0.06 1.55 +/- 0.20 11.91 +/- 0.85

23-24 1.27 0.61 0.52 6.91 0.81 +/- 0.05 0.11 +/- 0.02 1.54 +/- 0.10 1.06 +/- 0.04 1.85 +/- 0.14 12.97 +/- 0.58

23-24c

7.06 0.81 +/- 0.04

24-25 1.24 0.58 0.53 7.70 0.84 +/- 0.01 0.13 +/- 0.03 1.62 +/- 0.16 1.00 +/- 0.05 1.82 +/- 0.19 13.66 +/- 0.89

25-26 1.24 0.57 3.93 7.60 0.84 +/- 0.10 0.10 +/- 0.03 1.43 +/- 0.16 0.95 +/- 0.05 1.71 +/- 0.20 13.01 +/- 0.89

26-27 1.23 0.58 0.53 7.41 0.77 +/- 0.06 0.07 +/- 0.03 1.43 +/- 0.13 1.04 +/- 0.05 1.68 +/- 0.17 13.25 +/- 0.77

27-28 1.21 0.55 0.54 8.02 0.77 +/- 0.07 0.10 +/- 0.03 1.44 +/- 0.16 0.95 +/- 0.05 1.93 +/- 0.20 13.14 +/- 0.92

28-29 1.16 0.50 0.56 8.46 0.76 +/- 0.01 0.07 +/- 0.03 1.39 +/- 0.14 0.94 +/- 0.05 1.99 +/- 0.17 14.81 +/- 0.79

29-30 1.19 0.54 0.55 8.44 0.68 +/- 0.01 0.05 +/- 0.03 1.31 +/- 0.16 0.89 +/- 0.05 1.81 +/- 0.19 14.84 +/- 0.91

30-31 1.16 0.48 0.58 8.25 0.62 +/- 0.01 ND 1.09 +/- 0.15 0.81 +/- 0.05 1.86 +/- 0.19 13.75 +/- 0.92

31-32 1.16 0.49 0.58 8.45 0.68 +/- 0.01 ND 1.24 +/- 0.17 0.90 +/- 0.06 2.00 +/- 0.21 14.59 +/- 0.97

32-33 1.20 0.54 0.55 8.53 0.61 +/- 0.10 ND 0.93 +/- 0.13 0.87 +/- 0.05 1.69 +/- 0.17 14.33 +/- 0.80

33-34 1.15 0.48 0.58 8.45 0.70 +/- 0.01 ND 1.12 +/- 0.16 0.85 +/- 0.05 1.93 +/- 0.20 13.61 +/- 0.92

34-35 1.18 0.50 0.58 8.54 0.84 +/- 0.10 0.09 +/- 0.03 1.36 +/- 0.15 0.92 +/- 0.05 1.80 +/- 0.20 14.20 +/- 0.92

35-36 1.17 0.50 0.57 8.89 0.91 +/- 0.02 0.13 +/- 0.03 1.37 +/- 0.13 0.87 +/- 0.04 1.65 +/- 0.17 13.11 +/- 0.75

36-37 1.19 0.54 0.55 8.95 0.96 +/- 0.04 0.14 +/- 0.03 1.56 +/- 0.16 0.88 +/- 0.05 1.48 +/- 0.19 14.03 +/- 0.92

36-37c

8.75 0.87 +/- 0.04

37-38 1.19 0.54 0.55 8.89 0.99 +/- 0.05 0.11 +/- 0.03 1.38 +/- 0.17 0.89 +/- 0.05 1.40 +/- 0.19 12.62 +/- 0.89

38-39 1.22 0.57 0.53 8.68 1.08 +/- 0.04 0.14 +/- 0.03 1.45 +/- 0.12 0.89 +/- 0.04 1.46 +/- 0.15 13.92 +/- 0.76

39-40 1.21 0.59 0.51 6.97 0.87 +/- 0.02 0.11 +/- 0.03 1.31 +/- 0.13 0.96 +/- 0.04 1.46 +/- 0.16 13.21 +/- 0.73

40-41 1.18 0.56 0.53 6.80 0.79 +/- 0.08 0.13 +/- 0.03 1.34 +/- 0.13 0.97 +/- 0.04 1.71 +/- 0.16 13.65 +/- 0.73

41-42 1.15 0.51 0.56 6.89 0.68 +/- 0.03 0.09 +/- 0.02 1.27 +/- 0.11 0.92 +/- 0.04 1.79 +/- 0.14 13.47 +/- 0.64

42-43 1.25 0.61 0.51 6.84 0.70 +/- 0.18 0.06 +/- 0.02 1.26 +/- 0.13 0.91 +/- 0.04 1.70 +/- 0.17 13.06 +/- 0.75

43-44 1.26 0.62 0.50 6.55 0.71 +/- 0.01 0.12 +/- 0.03 1.41 +/- 0.14 0.94 +/- 0.05 1.62 +/- 0.17 13.55 +/- 0.78

43-44c

6.47 0.75 +/- 0.10

44-45 1.26 0.64 0.49 5.79 0.75 +/- 0.02 0.15 +/- 0.02 1.47 +/- 0.11 1.02 +/- 0.04 1.69 +/- 0.15 12.88 +/- 0.63

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.02 pCi/g; Lc:Pb-210 = 0.09 pCi/g; Lc:Ra-226 = 0.05 pCi/g; Lc:Th-234 = 0.12 pCi/g; Lc:K-40 = 0.31 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
10

Table 3. Physical and radioisotopic data for Mobile Bay core MB0810-4BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.20 0.36 0.70 13.52 1.76 +/- 0.03 0.10 +/- 0.03 2.49 +/- 0.15 0.78 +/- 0.04 1.22 +/- 0.13 14.79 +/- 0.84

1-2 1.15 0.33 0.72 13.84 1.47 +/- 0.03 0.10 +/- 0.02 2.74 +/- 0.12 0.79 +/- 0.03 1.40 +/- 0.12 12.68 +/- 0.55

2-3 1.22 0.41 0.67 12.66 1.79 +/- 0.03 0.11 +/- 0.02 2.78 +/- 0.11 0.77 +/- 0.03 1.40 +/- 0.10 12.47 +/- 0.50

3-4 1.24 0.40 0.68 13.87 1.68 +/- 0.03 0.10 +/- 0.02 2.59 +/- 0.11 0.76 +/- 0.03 1.48 +/- 0.11 12.63 +/- 0.55

4-5 1.22 0.41 0.66 14.99 1.77 +/- 0.03 0.09 +/- 0.02 2.73 +/- 0.14 0.79 +/- 0.04 1.43 +/- 0.13 12.77 +/- 0.62

5-6 1.19 0.39 0.67 13.19 1.34 +/- 0.03 0.12 +/- 0.02 2.79 +/- 0.12 0.80 +/- 0.04 1.46 +/- 0.13 15.28 +/- 0.71

6-7 1.20 0.37 0.69 13.35 1.53 +/- 0.03 0.10 +/- 0.02 2.71 +/- 0.12 0.78 +/- 0.04 1.44 +/- 0.12 13.13 +/- 0.61

7-8 1.23 0.43 0.65 12.92 1.48 +/- 0.03 0.10 +/- 0.02 2.71 +/- 0.13 0.77 +/- 0.04 1.32 +/- 0.12 12.66 +/- 0.63

8-9 1.22 0.42 0.66 12.54 1.68 +/- 0.03 0.11 +/- 0.02 2.80 +/- 0.11 0.77 +/- 0.03 1.49 +/- 0.11 12.67 +/- 0.51

9-10 1.26 0.48 0.62 12.61 1.79 +/- 0.02 0.12 +/- 0.02 2.68 +/- 0.14 0.74 +/- 0.04 1.47 +/- 0.14 12.80 +/- 0.69

10-11 1.21 0.42 0.65 12.07 1.67 +/- 0.03 0.10 +/- 0.02 2.67 +/- 0.13 0.82 +/- 0.04 1.55 +/- 0.13 11.74 +/- 0.62

11-12 1.21 0.47 0.62 11.72 1.57 +/- 0.03 0.11 +/- 0.02 2.51 +/- 0.13 0.84 +/- 0.04 1.46 +/- 0.14 12.69 +/- 0.69

11-12c

11.63 1.44 +/- 0.03

12-13 1.22 0.45 0.63 13.04 1.21 +/- 0.02 0.11 +/- 0.02 2.28 +/- 0.11 0.79 +/- 0.03 1.73 +/- 0.13 11.72 +/- 0.56

13-14 1.28 0.51 0.60 11.82 1.19 +/- 0.02 0.09 +/- 0.03 2.13 +/- 0.14 0.82 +/- 0.04 1.66 +/- 0.14 11.91 +/- 0.68

14-15 1.31 0.53 0.59 11.57 1.09 +/- 0.02 0.08 +/- 0.02 1.79 +/- 0.11 0.86 +/- 0.04 1.67 +/- 0.12 12.79 +/- 0.57

15-16 1.30 0.56 0.57 11.54 1.04 +/- 0.02 0.05 +/- 0.03 1.71 +/- 0.15 0.85 +/- 0.05 1.78 +/- 0.18 12.22 +/- 0.83

16-17 1.30 0.56 0.57 11.80 0.60 +/- 0.03 0.08 +/- 0.02 1.47 +/- 0.13 0.84 +/- 0.04 1.72 +/- 0.14 12.95 +/- 0.74

17-18 1.30 0.58 0.55 11.77 0.93 +/- 0.03 0.07 +/- 0.02 1.34 +/- 0.13 0.82 +/- 0.04 1.68 +/- 0.15 12.49 +/- 0.71

17-18c

11.55 1.00 +/- 0.03

18-19 1.33 0.58 0.56 11.75 0.70 +/- 0.02 0.03 +/- 0.02 1.32 +/- 0.12 0.85 +/- 0.04 1.78 +/- 0.14 12.76 +/- 0.65

19-20 1.31 0.60 0.54 11.94 0.73 +/- 0.03 ND 1.30 +/- 0.13 0.83 +/- 0.04 1.74 +/- 0.15 12.07 +/- 0.71

20-21 1.31 0.58 0.56 11.79 0.71 +/- 0.03 ND 1.31 +/- 0.21 0.83 +/- 0.07 1.46 +/- 0.21 12.29 +/- 1.10

21-22 1.31 0.58 0.56 12.31 0.85 +/- 0.04 ND 1.21 +/- 0.11 0.79 +/- 0.04 1.59 +/- 0.13 12.99 +/- 0.65

22-23 1.30 0.56 0.57 12.18 0.57 +/- 0.03 ND 1.26 +/- 0.12 0.84 +/- 0.04 1.68 +/- 0.14 13.35 +/- 0.73

23-24 1.31 0.59 0.55 12.01 0.44 +/- 0.04 ND 1.14 +/- 0.13 0.82 +/- 0.04 1.55 +/- 0.15 12.74 +/- 0.74

24-25 1.28 0.48 0.63 12.03 0.47 +/- 0.04 ND 1.12 +/- 0.12 0.76 +/- 0.04 1.41 +/- 0.13 12.75 +/- 0.71

24-25c

11.82 0.51 +/- 0.04

25-26 1.34 0.58 0.56 11.66 0.50 +/- 0.04 ND 1.04 +/- 0.09 0.79 +/- 0.03 1.61 +/- 0.13 13.12 +/- 0.59

26-27 1.32 0.63 0.52 11.59 0.29 +/- 0.05 ND 1.10 +/- 0.12 0.84 +/- 0.04 1.56 +/- 0.15 13.27 +/- 0.74

27-28 1.29 0.53 0.59 11.32 0.54 +/- 0.03 ND 1.07 +/- 0.13 0.84 +/- 0.04 1.56 +/- 0.16 13.65 +/- 0.74

28-29 1.30 0.57 0.57 11.28 0.51 +/- 0.03 ND 0.97 +/- 0.14 0.77 +/- 0.05 1.49 +/- 0.17 13.72 +/- 0.88

29-30 1.33 0.58 0.56 11.26 0.56 +/- 0.03 ND 0.97 +/- 0.15 0.83 +/- 0.05 1.47 +/- 0.17 12.39 +/- 0.88

30-31 1.33 0.58 0.57 11.38 0.55 +/- 0.03 ND 0.98 +/- 0.13 0.81 +/- 0.05 1.56 +/- 0.16 12.69 +/- 0.76

30-31c

11.33 0.48 +/- 0.03

31-32 1.28 0.60 0.53 9.64 0.57 +/- 0.04 ND 0.93 +/- 0.12 0.77 +/- 0.04 1.51 +/- 0.15 13.09 +/- 0.72

32-33 1.32 0.59 0.56 9.64 0.52 +/- 0.03 ND 1.02 +/- 0.11 0.77 +/- 0.04 1.58 +/- 0.13 12.28 +/- 0.64

33-34 1.32 0.58 0.56 9.46 0.52 +/- 0.04 ND 0.90 +/- 0.14 0.74 +/- 0.05 1.59 +/- 0.18 12.63 +/- 0.80

34-35 1.31 0.56 0.57 9.69 0.58 +/- 0.04 ND 1.01 +/- 0.10 0.76 +/- 0.03 1.70 +/- 0.13 14.11 +/- 0.60

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.02 pCi/g; Lc:Pb-210 = 0.12 pCi/g; Lc:Ra-226 = 0.07 pCi/g; Lc:Th-234 = 0.13 pCi/g; Lc:K-40 = 0.36 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
11

Table 4. Physical and radioisotopic data for Mobile Bay core MB0810-5BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.08 0.39 0.64 10.59 1.98 +/- 0.02 0.06 +/- 0.02 2.07 +/- 0.13 0.66 +/- 0.04 0.91 +/- 0.13 9.29 +/- 0.60

1-2 1.13 0.42 0.62 10.19 1.82 +/- 0.12 0.09 +/- 0.02 2.51 +/- 0.12 0.83 +/- 0.03 1.40 +/- 0.12 12.27 +/- 0.57

2-3 1.11 0.41 0.63 9.83 1.61 +/- 0.07 0.08 +/- 0.03 2.51 +/- 0.17 0.86 +/- 0.05 1.45 +/- 0.16 11.54 +/- 0.76

3-4 1.13 0.47 0.58 9.71 1.87 +/- 0.02 0.07 +/- 0.03 2.40 +/- 0.16 0.86 +/- 0.05 1.40 +/- 0.16 12.27 +/- 0.78

3-4c

8.15 1.92 +/- 0.03

4-5 1.12 0.43 0.62 9.86 1.85 +/- 0.15 0.08 +/- 0.03 2.42 +/- 0.17 0.84 +/- 0.05 1.38 +/- 0.18 11.56 +/- 0.81

5-6 1.16 0.45 0.61 9.82 1.68 +/- 0.04 0.10 +/- 0.03 2.60 +/- 0.17 0.88 +/- 0.05 1.44 +/- 0.17 11.28 +/- 0.78

6-7 1.10 0.40 0.63 8.75 1.34 +/- 0.03 0.07 +/- 0.02 2.18 +/- 0.14 0.78 +/- 0.04 1.21 +/- 0.14 10.38 +/- 0.67

7-8 1.15 0.46 0.60 9.61 1.10 +/- 0.08 0.04 +/- 0.02 1.82 +/- 0.16 0.89 +/- 0.05 1.53 +/- 0.18 12.42 +/- 0.81

8-9 1.18 0.51 0.57 9.14 0.87 +/- 0.05 ND 1.33 +/- 0.10 0.83 +/- 0.03 1.52 +/- 0.12 13.47 +/- 0.59

9-10 1.20 0.54 0.55 9.01 0.79 +/- 0.03 ND 1.15 +/- 0.13 0.86 +/- 0.04 1.40 +/- 0.15 13.50 +/- 0.72

10-11 1.18 0.50 0.58 9.72 0.73 +/- 0.03 ND 1.23 +/- 0.11 0.89 +/- 0.04 1.42 +/- 0.14 14.04 +/- 0.67

11-12 1.16 0.49 0.58 9.99 0.89 +/- 0.02 ND 1.21 +/- 0.14 0.85 +/- 0.05 1.39 +/- 0.17 12.84 +/- 0.81

12-13 1.21 0.56 0.54 9.45 0.78 +/- 0.03 ND 1.08 +/- 0.15 0.85 +/- 0.05 1.57 +/- 0.19 14.07 +/- 0.91

12-13c

7.83 0.63 +/- 0.05

13-14 1.18 0.52 0.55 9.29 0.67 +/- 0.15 ND 1.03 +/- 0.12 0.89 +/- 0.04 1.46 +/- 0.16 13.52 +/- 0.74

14-15 1.19 0.49 0.59 10.10 0.76 +/- 0.01 ND 1.10 +/- 0.12 0.85 +/- 0.04 1.39 +/- 0.14 12.82 +/- 0.73

15-16 1.18 0.49 0.58 10.96 0.75 +/- 0.03 ND 1.19 +/- 0.12 0.86 +/- 0.04 1.54 +/- 0.16 13.61 +/- 0.73

16-17 1.17 0.45 0.61 10.62 0.73 +/- 0.01 ND 1.15 +/- 0.15 0.82 +/- 0.05 1.36 +/- 0.18 13.67 +/- 0.85

17-18 1.17 0.49 0.58 9.98 0.64 +/- 0.18 ND 1.03 +/- 0.16 0.84 +/- 0.06 1.34 +/- 0.19 13.39 +/- 0.95

18-19 1.19 0.50 0.58 9.38 0.70 +/- 0.15 ND 1.07 +/- 0.13 0.82 +/- 0.04 1.44 +/- 0.16 12.80 +/- 0.76

19-20 1.21 0.50 0.59 10.10 0.78 +/- 0.08 ND 1.10 +/- 0.15 0.87 +/- 0.05 1.31 +/- 0.19 13.09 +/- 0.86

20-21 1.18 0.48 0.60 10.56 0.73 +/- 0.08 ND 1.14 +/- 0.17 0.83 +/- 0.05 1.54 +/- 0.20 12.61 +/- 0.89

21-22 1.16 0.48 0.59 9.81 0.71 +/- 0.01 ND 1.08 +/- 0.13 0.85 +/- 0.04 1.35 +/- 0.16 13.00 +/- 0.72

22-23 1.18 0.48 0.60 9.45 0.78 +/- 0.04 ND 1.15 +/- 0.13 0.88 +/- 0.05 1.41 +/- 0.17 13.34 +/- 0.77

23-24 1.15 0.46 0.60 9.46 0.71 +/- 0.01 ND 1.17 +/- 0.11 0.86 +/- 0.04 1.49 +/- 0.13 13.08 +/- 0.63

24-25 1.16 0.49 0.58 9.44 0.80 +/- 0.23 ND 1.15 +/- 0.15 0.87 +/- 0.05 1.40 +/- 0.18 12.72 +/- 0.84

24-25c

9.44 0.66 +/- 0.04

25-26 1.20 0.53 0.56 9.50 0.63 +/- 0.17 ND 1.12 +/- 0.16 0.92 +/- 0.05 1.50 +/- 0.19 13.81 +/- 0.91

26-27 1.22 0.53 0.56 8.03 0.63 +/- 0.09 ND 1.03 +/- 0.13 0.90 +/- 0.05 1.30 +/- 0.15 12.26 +/- 0.74

26-27c

8.03 0.58 +/- 0.01

27-28 1.20 0.53 0.56 9.17 0.62 +/- 0.05 ND 1.00 +/- 0.16 0.86 +/- 0.05 1.21 +/- 0.18 11.98 +/- 0.82

28-29 1.19 0.53 0.56 9.10 0.66 +/- 0.04 ND 1.12 +/- 0.16 0.89 +/- 0.05 1.51 +/- 0.20 12.50 +/- 0.86

29-30 1.18 0.51 0.57 9.16 0.64 +/- 0.02 ND 1.01 +/- 0.16 0.89 +/- 0.05 1.48 +/- 0.18 12.67 +/- 0.82

29-30c

7.61 0.66 +/- 0.04

30-31 1.20 0.53 0.55 9.25 0.61 +/- 0.02 ND 1.05 +/- 0.13 0.90 +/- 0.05 1.40 +/- 0.16 13.22 +/- 0.75

31-32 1.20 0.54 0.55 9.53 0.67 +/- 0.05 ND 1.16 +/- 0.16 0.83 +/- 0.05 1.46 +/- 0.18 12.48 +/- 0.84

32-33 1.15 0.48 0.58 9.84 0.66 +/- 0.01 ND 1.03 +/- 0.16 0.86 +/- 0.05 1.43 +/- 0.18 12.23 +/- 0.86

33-34 1.18 0.50 0.58 9.36 0.62 +/- 0.05 ND 1.05 +/- 0.13 0.85 +/- 0.04 1.29 +/- 0.15 12.42 +/- 0.72

34-35 1.17 0.50 0.58 9.25 0.61 +/- 0.02 ND 1.03 +/- 0.16 0.86 +/- 0.05 1.28 +/- 0.17 13.81 +/- 0.90

35-36 1.17 0.50 0.57 9.30 0.52 +/- 0.01 ND 0.98 +/- 0.12 0.81 +/- 0.04 1.31 +/- 0.16 12.85 +/- 0.75

36-37 1.24 0.58 0.53 9.75 0.57 +/- 0.02

37-38 1.22 0.57 0.53 9.09 0.50 +/- 0.02 ND 0.92 +/- 0.15 0.80 +/- 0.05 1.43 +/- 0.18 12.92 +/- 0.83

38-39 1.11 0.48 0.57 8.87 0.51 +/- 0.08

39-40 1.19 0.55 0.54 8.87 0.48 +/- 0.01 ND 0.89 +/- 0.13 0.84 +/- 0.04 1.42 +/- 0.17 12.87 +/- 0.76

40-41 1.23 0.56 0.55 9.31 0.56 +/- 0.08

41-42 1.20 0.55 0.54 8.75 0.55 +/- 0.01 ND 0.94 +/- 0.14 0.80 +/- 0.05 1.22 +/- 0.18 12.97 +/- 0.85

42-43 1.21 0.56 0.53 8.26 0.51 +/- 0.04 ND 0.91 +/- 0.11 0.80 +/- 0.04 1.34 +/- 0.16 12.43 +/- 0.71

43-44 1.20 0.56 0.53 7.98 0.40 +/- 0.04

43-44c

9.81 0.36 +/- 0.03

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.02 pCi/g; Lc:Pb-210 = 0.10 pCi/g; Lc:Ra-226 = 0.05 pCi/g; Lc:Th-234 = 0.12 pCi/g; Lc:K-40 = 0.28 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
12

Table 5. Physical and radioisotopic data for Mobile Bay core MB0810-7BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.11 0.41 0.63 10.64 2.19 +/- 0.02 0.10 +/- 0.02 2.85 +/- 0.15 0.71 +/- 0.04 1.00 +/- 0.15 11.20 +/- 0.73

1-2 1.12 0.43 0.61 10.29 2.37 +/- 0.05 0.11 +/- 0.03 2.66 +/- 0.19 0.64 +/- 0.05 0.89 +/- 0.16 11.75 +/- 0.86

2-3 1.12 0.49 0.56 9.84 2.03 +/- 0.09 0.12 +/- 0.03 2.55 +/- 0.18 0.64 +/- 0.05 0.92 +/- 0.16 10.98 +/- 0.83

3-4 1.16 0.45 0.61 8.94 1.96 +/- 0.08 0.09 +/- 0.02 2.54 +/- 0.15 0.70 +/- 0.04 1.05 +/- 0.14 10.19 +/- 0.69

4-5 1.15 0.47 0.59 9.06 1.81 +/- 0.12 0.09 +/- 0.02 2.54 +/- 0.15 0.67 +/- 0.04 1.06 +/- 0.13 10.30 +/- 0.68

4-5c

7.76 1.91 +/- 0.25

5-6 1.15 0.46 0.61 9.03 1.89 +/- 0.08 0.10 +/- 0.02 2.38 +/- 0.12 0.64 +/- 0.03 0.91 +/- 0.11 10.72 +/- 0.57

6-7 1.19 0.50 0.58 9.18 2.01 +/- 0.04 0.11 +/- 0.02 2.61 +/- 0.15 0.65 +/- 0.04 1.07 +/- 0.13 10.33 +/- 0.68

7-8 1.08 0.38 0.65 9.38 1.99 +/- 0.03 0.09 +/- 0.04 2.70 +/- 0.23 0.63 +/- 0.06 1.01 +/- 0.19 10.61 +/- 1.04

8-9 1.13 0.44 0.61 9.81 2.01 +/- 0.06 0.10 +/- 0.02 2.70 +/- 0.13 0.71 +/- 0.04 1.12 +/- 0.13 11.13 +/- 0.61

9-10 1.15 0.48 0.58 9.84 1.98 +/- 0.01 0.11 +/- 0.03 2.66 +/- 0.18 0.74 +/- 0.05 1.12 +/- 0.16 10.65 +/- 0.8

10-11 1.19 0.49 0.59 8.55 1.77 +/- 0.01 0.11 +/- 0.02 2.43 +/- 0.15 0.61 +/- 0.04 0.94 +/- 0.13 10.56 +/- 0.66

11-12 1.18 0.48 0.59 9.19 1.95 +/- 0.15 0.12 +/- 0.03 2.33 +/- 0.16 0.63 +/- 0.05 0.97 +/- 0.15 10.38 +/- 0.82

12-13 1.18 0.48 0.59 8.95 1.70 +/- 0.07 0.10 +/- 0.02 2.39 +/- 0.15 0.66 +/- 0.04 1.11 +/- 0.14 9.68 +/- 0.69

13-14 1.19 0.49 0.59 9.56 1.78 +/- 0.10 0.09 +/- 0.02 2.41 +/- 0.12 0.66 +/- 0.03 1.14 +/- 0.12 10.93 +/- 0.59

14-15 1.16 0.48 0.59 8.48 1.72 +/- 0.02 0.09 +/- 0.03 2.31 +/- 0.19 0.67 +/- 0.05 1.07 +/- 0.16 10.16 +/- 0.81

15-16 1.20 0.51 0.57 7.66 1.48 +/- 0.08 0.08 +/- 0.02 2.09 +/- 0.12 0.66 +/- 0.04 0.96 +/- 0.11 9.50 +/- 0.57

16-17 1.17 0.52 0.55 7.61 1.68 +/- 0.13 0.08 +/- 0.03 2.28 +/- 0.17 0.64 +/- 0.05 0.97 +/- 0.14 10.07 +/- 0.77

16-17c

6.68 1.49 +/- 0.16

17-18 1.20 0.52 0.57 7.99 1.56 +/- 0.05 0.09 +/- 0.03 1.98 +/- 0.17 0.62 +/- 0.05 1.11 +/- 0.16 9.74 +/- 0.78

18-19 1.28 0.60 0.53 7.75 1.58 +/- 0.01 0.10 +/- 0.02 2.16 +/- 0.14 0.65 +/- 0.04 1.04 +/- 0.14 9.26 +/- 0.65

19-20 1.20 0.51 0.57 7.15 1.72 +/- 0.06 0.09 +/- 0.03 1.99 +/- 0.17 0.62 +/- 0.05 0.91 +/- 0.16 9.78 +/- 0.79

20-21 1.23 0.59 0.52 6.69 1.54 +/- 0.02 0.09 +/- 0.03 2.06 +/- 0.17 0.65 +/- 0.05 0.95 +/- 0.16 9.37 +/- 0.76

20-21c

6.20 1.43 +/- 0.05

21-22 1.21 0.58 0.52 7.82 1.54 +/- 0.05 0.09 +/- 0.03 2.00 +/- 0.14 0.61 +/- 0.04 0.98 +/- 0.13 9.66 +/- 0.67

22-23 1.28 0.65 0.49 8.25 1.55 +/- 0.02 0.08 +/- 0.03 2.07 +/- 0.16 0.61 +/- 0.05 1.14 +/- 0.16 9.60 +/- 0.76

23-24 1.25 0.64 0.49 7.10 1.42 +/- 0.02 0.06 +/- 0.03 2.01 +/- 0.16 0.67 +/- 0.05 1.15 +/- 0.16 9.96 +/- 0.78

24-25 1.31 0.69 0.48 6.75 1.27 +/- 0.05 0.07 +/- 0.02 1.87 +/- 0.14 0.60 +/- 0.04 1.12 +/- 0.14 9.73 +/- 0.68

25-26 1.26 0.63 0.50 6.44 1.09 +/- 0.06 0.05 +/- 0.03 1.64 +/- 0.17 0.62 +/- 0.05 1.16 +/- 0.17 9.49 +/- 0.78

26-27 1.28 0.63 0.51 7.52 0.98 +/- 0.03 0.08 +/- 0.03 1.50 +/- 0.15 0.67 +/- 0.05 1.13 +/- 0.16 8.27 +/- 0.72

26-27c

5.67 0.96 +/- 0.01

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.03 pCi/g; Lc:Pb-210 = 0.10 pCi/g; Lc:Ra-226 = 0.05 pCi/g; Lc:Th-234 = 0.12 pCi/g; Lc:K-40 = 0.32 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
13

Table 6. Physical and radioisotopic data for Mobile Bay core MB0810-8BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.22 0.46 0.62 14.48 3.16 +/- 0.06 0.12 +/- 0.02 3.91 +/- 0.17 0.67 +/- 0.04 1.05 +/- 0.14 10.44 +/- 0.66

1-2 1.22 0.44 0.64 14.28 3.37 +/- 0.13 0.13 +/- 0.03 3.76 +/- 0.16 0.64 +/- 0.04 0.99 +/- 0.14 11.16 +/- 0.68

1-2c

12.57 2.98 +/- 0.03

2-3 1.22 0.45 0.63 14.61 3.41 +/- 0.03 0.11 +/- 0.03 3.99 +/- 0.20 0.61 +/- 0.05 1.06 +/- 0.16 9.97 +/- 0.75

3-4 1.15 0.36 0.68 15.02 3.05 +/- 0.08 0.13 +/- 0.04 4.18 +/- 0.29 0.68 +/- 0.06 0.95 +/- 0.23 12.39 +/- 1.13

4-5 1.19 0.34 0.71 14.04 3.29 +/- 0.01 0.12 +/- 0.02 3.61 +/- 0.15 0.68 +/- 0.04 0.97 +/- 0.12 10.61 +/- 0.59

5-6 1.23 0.39 0.68 13.13 3.03 +/- 0.09 0.14 +/- 0.03 3.57 +/- 0.20 0.66 +/- 0.05 1.02 +/- 0.16 10.94 +/- 0.80

6-7 1.19 0.38 0.69 12.52 3.11 +/- 0.19 0.10 +/- 0.02 3.40 +/- 0.15 0.66 +/- 0.04 1.08 +/- 0.12 10.97 +/- 0.64

7-8 1.23 0.44 0.65 12.48 2.79 +/- 0.09 0.12 +/- 0.03 3.26 +/- 0.20 0.65 +/- 0.05 1.07 +/- 0.16 10.23 +/- 0.79

8-9 1.21 0.43 0.64 13.36 2.74 +/- 0.11 0.13 +/- 0.03 3.18 +/- 0.17 0.70 +/- 0.05 1.06 +/- 0.14 12.25 +/- 0.88

9-10 1.24 0.44 0.64 11.41 2.45 +/- 0.06 0.08 +/- 0.02 3.21 +/- 0.14 0.69 +/- 0.03 1.05 +/- 0.11 9.63 +/- 0.54

10-11 1.25 0.47 0.62 9.07 2.29 +/- 0.08 0.10 +/- 0.03 3.21 +/- 0.19 0.75 +/- 0.05 1.07 +/- 0.15 8.82 +/- 0.74

11-12 1.26 0.48 0.62 8.71 2.41 +/- 0.12 0.10 +/- 0.02 3.06 +/- 0.15 0.71 +/- 0.04 1.05 +/- 0.12 9.83 +/- 0.66

11-12c

8.89 2.17 +/- 0.01

12-13 1.28 0.50 0.61 9.41 2.61 +/- 0.18 0.08 +/- 0.03 3.22 +/- 0.18 0.67 +/- 0.05 1.15 +/- 0.16 9.08 +/- 0.73

13-14 1.26 0.48 0.62 8.04 2.19 +/- 0.34 0.10 +/- 0.03 3.08 +/- 0.19 0.71 +/- 0.05 1.08 +/- 0.15 9.62 +/- 0.74

14-15 1.29 0.54 0.58 8.31 2.13 +/- 0.07 0.09 +/- 0.03 2.77 +/- 0.17 0.70 +/- 0.05 1.10 +/- 0.15 10.55 +/- 0.83

14-15c

8.33 1.95 +/- 0.15

15-16 1.30 0.56 0.57 8.16 2.01 +/- 0.19 0.06 +/- 0.03 2.78 +/- 0.18 0.64 +/- 0.05 1.09 +/- 0.15 9.36 +/- 0.76

16-17 1.33 0.57 0.57 8.05 2.10 +/- 0.06 0.09 +/- 0.03 2.75 +/- 0.19 0.70 +/- 0.05 1.12 +/- 0.15 8.71 +/- 0.72

17-18 1.28 0.52 0.59 7.47 1.76 +/- 0.12 0.06 +/- 0.03 2.70 +/- 0.18 0.68 +/- 0.05 1.01 +/- 0.16 8.80 +/- 0.70

18-19 1.30 0.58 0.55 6.30 1.69 +/- 0.03 0.08 +/- 0.03 2.41 +/- 0.18 0.71 +/- 0.05 1.15 +/- 0.17 8.28 +/- 0.72

19-20 1.31 0.59 0.55 5.96 1.45 +/- 0.02 0.09 +/- 0.03 2.04 +/- 0.15 0.67 +/- 0.04 1.11 +/- 0.14 9.00 +/- 0.64

20-21 1.29 0.57 0.56 5.93 1.28 +/- 0.04 0.05 +/- 0.02 1.83 +/- 0.15 0.73 +/- 0.05 1.19 +/- 0.16 9.13 +/- 0.70

21-22 1.30 0.59 0.54 8.82 1.24 +/- 0.04 0.06 +/- 0.03 1.79 +/- 0.18 0.74 +/- 0.05 1.24 +/- 0.17 8.84 +/- 0.75

22-23 1.34 0.61 0.54 7.63 1.13 +/- 0.04 0.04 +/- 0.02 1.73 +/- 0.15 0.73 +/- 0.04 1.26 +/- 0.15 9.22 +/- 0.66

22-23c

7.77 0.99 +/- 0.05

23-24 1.38 0.64 0.54 8.99 1.00 +/- 0.07 ND 1.43 +/- 0.16 0.72 +/- 0.05 1.10 +/- 0.15 9.30 +/- 0.73

24-25 1.36 0.62 0.54 8.95 1.08 +/- 0.05 ND 1.56 +/- 0.16 0.80 +/- 0.05 1.20 +/- 0.19 10.00 +/- 0.78

25-26 1.32 0.60 0.55 8.70 1.06 +/- 0.01

26-27 1.30 0.58 0.56 8.73 1.06 +/- 0.07 0.03 +/- 0.02 1.69 +/- 0.14 0.72 +/- 0.04 1.10 +/- 0.14 10.02 +/- 0.64

27-28 1.32 0.61 0.54 9.94 1.03 +/- 0.06

28-29 1.31 0.56 0.58 10.35 1.08 +/- 0.12 ND 1.55 +/- 0.17 0.75 +/- 0.05 1.34 +/- 0.18 12.00 +/- 0.83

29-30 1.34 0.60 0.55 10.05 1.07 +/- 0.01 ND 1.53 +/- 0.16 0.82 +/- 0.05 1.23 +/- 0.16 11.52 +/- 0.77

30-31 1.28 0.55 0.57 10.23 1.32 +/- 0.05 0.03 +/- 0.02 1.76 +/- 0.12 0.82 +/- 0.04 1.34 +/- 0.13 11.83 +/- 0.61

31-32 1.28 0.57 0.56 10.68 1.29 +/- 0.03 ND 1.91 +/- 0.18 0.78 +/- 0.05 1.24 +/- 0.18 12.06 +/- 0.84

32-33 1.33 0.62 0.53 10.68 1.55 +/- 0.20 0.04 +/- 0.02 1.96 +/- 0.15 0.77 +/- 0.04 1.38 +/- 0.15 11.60 +/- 0.69

33-34 1.30 0.61 0.53 10.17 1.30 +/- 0.12 ND 1.56 +/- 0.15 0.82 +/- 0.05 1.33 +/- 0.15 12.14 +/- 0.74

34-35 1.32 0.60 0.55 10.27 0.86 +/- 0.04 ND 1.41 +/- 0.16 0.99 +/- 0.05 1.38 +/- 0.17 15.66 +/- 0.94

35-36 1.33 0.60 0.55 10.71 0.88 +/- 0.04 ND 1.28 +/- 0.14 0.92 +/- 0.05 1.35 +/- 0.15 12.68 +/- 0.71

35-36c

10.05 0.80 +/- 0.04

36-37 1.33 0.60 0.55 10.10 0.87 +/- 0.01 ND 1.37 +/- 0.15 0.87 +/- 0.05 1.36 +/- 0.16 11.69 +/- 0.73

37-38 1.31 0.58 0.56 10.78 0.87 +/- 0.04 ND 1.27 +/- 0.11 0.84 +/- 0.04 1.54 +/- 0.13 12.26 +/- 0.60

38-39 1.32 0.57 0.57 10.88 0.84 +/- 0.06 ND 1.32 +/- 0.18 0.87 +/- 0.05 1.39 +/- 0.18 11.63 +/- 0.77

39-40 1.30 0.59 0.55 10.09 0.92 +/- 0.04 ND 1.40 +/- 0.13 0.81 +/- 0.04 1.23 +/- 0.12 10.79 +/- 0.60

40-41 1.33 0.59 0.56 9.44 0.96 +/- 0.01 ND 1.40 +/- 0.16 0.89 +/- 0.05 1.39 +/- 0.18 12.35 +/- 0.85

41-42 1.35 0.63 0.54 10.79 0.93 +/- 0.04

42-43 1.39 0.68 0.51 10.24 0.96 +/- 0.01 ND 1.31 +/- 0.15 0.91 +/- 0.05 1.31 +/- 0.17 10.77 +/- 0.77

43-44 1.33 0.64 0.52 9.11 0.83 +/- 0.02

44-45 1.33 0.65 0.51 9.23 0.72 +/- 0.04 ND 1.15 +/- 0.15 0.82 +/- 0.05 1.34 +/- 0.18 11.53 +/- 0.83

45-46 1.34 0.65 0.51 9.62 0.82 +/- 0.02

46-47 1.36 0.65 0.52 9.62 0.77 +/- 0.03 ND 1.16 +/- 0.12 0.82 +/- 0.04 1.41 +/- 0.14 11.35 +/- 0.60

47-48 1.37 0.68 0.50 8.94 0.70 +/- 0.03

48-49 1.28 0.59 0.54 9.98 0.87 +/- 0.03 ND 1.25 +/- 0.15 0.87 +/- 0.05 1.24 +/- 0.17 12.32 +/- 0.81

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.03 pCi/g; Lc:Pb-210 = 0.13 pCi/g; Lc:Ra-226 = 0.07 pCi/g; Lc:Th-234 = 0.15 pCi/g; Lc:K-40 = 0.38 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
14

Table 7. Physical and radioisotopic data for Mobile Bay core MB0810-12BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.13 0.39 0.65 9.58 1.95 +/- 0.21 0.10 +/- 0.02 2.84 +/- 0.14 0.77 +/- 0.04 1.20 +/- 0.13 10.13 +/- 0.57

1-2 1.12 0.37 0.67 9.26 1.94 +/- 0.01 0.08 +/- 0.03 2.83 +/- 0.16 0.75 +/- 0.04 1.04 +/- 0.14 9.93 +/- 0.68

2-3 1.27 0.53 0.59 8.58 1.87 +/- 0.04 0.12 +/- 0.05 2.57 +/- 0.24 0.78 +/- 0.07 1.17 +/- 0.21 9.99 +/- 1.05

3-4 1.23 0.45 0.63 8.00 1.79 +/- 0.04 0.07 +/- 0.03 2.34 +/- 0.15 0.81 +/- 0.05 1.36 +/- 0.15 9.35 +/- 0.66

3-4c

9.39 1.64 +/- 0.01

4-5 1.30 0.52 0.60 8.61 1.44 +/- 0.07 0.11 +/- 0.03 1.85 +/- 0.17 0.83 +/- 0.05 1.55 +/- 0.18 10.99 +/- 0.78

5-6 1.28 0.53 0.59 8.49 1.31 +/- 0.03 0.09 +/- 0.03 1.84 +/- 0.17 0.77 +/- 0.05 1.53 +/- 0.18 11.71 +/- 0.83

6-7 1.35 0.57 0.58 9.14 1.17 +/- 0.05 0.08 +/- 0.03 1.68 +/- 0.14 0.84 +/- 0.05 1.62 +/- 0.15 11.14 +/- 0.72

7-8 1.38 0.59 0.57 9.20 1.13 +/- 0.04 0.08 +/- 0.03 1.55 +/- 0.14 0.79 +/- 0.05 1.58 +/- 0.16 11.01 +/- 0.78

8-9 1.31 0.55 0.58 9.08 1.13 +/- 0.05 0.07 +/- 0.02 1.61 +/- 0.11 0.74 +/- 0.03 1.64 +/- 0.12 11.38 +/- 0.54

9-10 1.40 0.61 0.57 8.76 1.10 +/- 0.08 0.06 +/- 0.03 1.73 +/- 0.15 0.74 +/- 0.05 1.59 +/- 0.17 11.93 +/- 0.82

10-11 1.30 0.55 0.58 9.43 1.03 +/- 0.11 0.06 +/- 0.03 1.43 +/- 0.16 0.73 +/- 0.05 1.55 +/- 0.17 10.54 +/- 0.81

11-12 1.33 0.56 0.58 9.51 1.12 +/- 0.06 0.06 +/- 0.03 1.57 +/- 0.14 0.79 +/- 0.05 1.73 +/- 0.16 11.58 +/- 0.72

12-13 1.37 0.59 0.57 9.16 0.93 +/- 0.01 0.06 +/- 0.03 1.44 +/- 0.15 0.79 +/- 0.05 1.50 +/- 0.16 11.38 +/- 0.78

13-14 1.29 0.53 0.59 8.72 0.88 +/- 0.01 0.05 +/- 0.02 1.43 +/- 0.14 0.79 +/- 0.04 1.70 +/- 0.16 11.82 +/- 0.70

13-14c

9.39 0.84 +/- 0.01

14-15 1.27 0.50 0.61 9.21 0.98 +/- 0.05 0.03 +/- 0.03 1.29 +/- 0.16 0.85 +/- 0.05 1.42 +/- 0.17 12.40 +/- 0.82

15-16 1.29 0.57 0.56 8.91 0.83 +/- 0.01 ND 1.33 +/- 0.16 0.83 +/- 0.05 1.51 +/- 0.19 11.73 +/- 0.84

16-17 1.28 0.51 0.60 8.74 0.91 +/- 0.04 ND 1.51 +/- 0.17 0.82 +/- 0.05 1.47 +/- 0.17 12.26 +/- 0.86

17-18 1.29 0.53 0.59 9.05 0.86 +/- 0.01 ND 1.38 +/- 0.15 0.82 +/- 0.04 1.47 +/- 0.17 12.21 +/- 0.74

18-19 1.29 0.53 0.59 8.67 0.77 +/- 0.01 ND 1.23 +/- 0.15 0.78 +/- 0.05 1.45 +/- 0.19 12.78 +/- 0.82

19-20 1.22 0.50 0.59 8.18 0.78 +/- 0.10 ND 1.23 +/- 0.16 0.85 +/- 0.05 1.41 +/- 0.19 11.37 +/- 0.83

19-20c

9.39 0.79 +/- 0.02

20-21 1.30 0.56 0.57 8.23 0.80 +/- 0.01 ND 1.32 +/- 0.13 0.84 +/- 0.05 1.48 +/- 0.15 11.63 +/- 0.72

21-22 1.24 0.49 0.60 8.01 0.82 +/- 0.02 ND 1.30 +/- 0.15 0.86 +/- 0.05 1.45 +/- 0.17 12.53 +/- 0.84

22-23 1.38 0.64 0.54 7.60 0.77 +/- 0.04 ND 1.29 +/- 0.15 0.91 +/- 0.05 1.46 +/- 0.17 12.30 +/- 0.85

23-24 1.35 0.58 0.57 7.75 0.70 +/- 0.02 ND 1.25 +/- 0.14 0.88 +/- 0.04 1.44 +/- 0.14 12.08 +/- 0.73

24-25 1.33 0.57 0.57 7.44 0.72 +/- 0.01 ND 1.33 +/- 0.16 0.93 +/- 0.05 1.40 +/- 0.18 10.85 +/- 0.82

25-26 1.30 0.54 0.58 9.98 0.79 +/- 0.09 ND 1.26 +/- 0.13 0.87 +/- 0.04 1.35 +/- 0.14 12.12 +/- 0.70

26-27 1.34 0.59 0.56 9.88 0.76 +/- 0.01 ND 1.22 +/- 0.13 0.87 +/- 0.04 1.31 +/- 0.14 11.80 +/- 0.68

27-28 1.33 0.56 0.57 9.80 0.85 +/- 0.01 ND 1.28 +/- 0.14 0.84 +/- 0.04 1.37 +/- 0.14 12.09 +/- 0.69

27-28c

9.39 0.75 +/- 0.01

28-29 1.35 0.59 0.56 10.29 0.83 +/- 0.03 ND 1.18 +/- 0.12 0.88 +/- 0.04 1.31 +/- 0.14 12.80 +/- 0.64

29-30 1.28 0.52 0.59 9.89 0.81 +/- 0.08 ND 1.17 +/- 0.14 0.84 +/- 0.05 1.33 +/- 0.17 12.03 +/- 0.80

30-31 1.28 0.51 0.60 9.71 0.74 +/- 0.01

31-32 1.29 0.55 0.58 10.65 0.80 +/- 0.06

32-33 1.34 0.59 0.56 10.19 0.76 +/- 0.05

33-34 1.42 0.66 0.54 9.17 0.80 +/- 0.05

34-35 1.37 0.56 0.59 7.73 0.65 +/- 0.03

35-36 1.32 0.54 0.59 9.07 0.73 +/- 0.01

35-36c

9.39 0.73 +/- 0.02

36-37 1.32 0.55 0.59 9.11 0.71 +/- 0.03

37-38 1.35 0.53 0.61 9.39 0.72 +/- 0.03

38-39 1.32 0.51 0.61

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.04 pCi/g; Lc:Pb-210 = 0.11 pCi/g; Lc:Ra-226 = 0.07 pCi/g; Lc:Th-234 = 0.13 pCi/g; Lc:K-40 = 0.40 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]
15

Table 8. Physical and radioisotopic data for Mobile Bay core MB0810-20BC.

Depth (cm)

Wet Bulk

Density 

(g/cm

3

)

Dry Bulk

Density

(g/cm

3

)

Water

Content 

(% Mass)

Loss On 

Ignition (g 

OM/g sed) Pb-210

a

 (pCi/g)

Cs-137b 

(pCi/g)

Pb-210

b 

(pCi/g)

Ra-226b 

(pCi/g) Th-234

b

 (pCi/g)

K-40b 

(pCi/g)

0-1 1.05 0.32 0.70 12.02 2.49 +/- 0.01 0.13 +/- 0.03 3.28 +/- 0.15 0.69 +/- 0.04 1.04 +/- 0.14 11.33 +/- 0.66

1-2 1.08 0.36 0.67 12.11 2.50 +/- 0.01 0.12 +/- 0.02 3.36 +/- 0.14 0.68 +/- 0.04 1.07 +/- 0.12 11.62 +/- 0.61

2-3 1.10 0.34 0.69 11.16 2.51 +/- 0.28 0.12 +/- 0.04 3.26 +/- 0.21 0.69 +/- 0.06 1.07 +/- 0.17 13.79 +/- 1.07

3-4 1.07 0.33 0.69 11.29 2.53 +/- 0.11 0.12 +/- 0.04 3.43 +/- 0.23 0.72 +/- 0.06 1.11 +/- 0.19 13.25 +/- 1.13

4-5 1.07 0.34 0.68 12.36 2.33 +/- 0.15 0.12 +/- 0.03 3.29 +/- 0.19 0.75 +/- 0.05 1.25 +/- 0.17 12.64 +/- 0.99

5-6 1.08 0.35 0.68 12.28 2.67 +/- 0.06 0.11 +/- 0.03 3.36 +/- 0.16 0.74 +/- 0.05 1.18 +/- 0.15 13.71 +/- 0.89

6-7 1.04 0.33 0.68 12.42 2.58 +/- 0.55 0.14 +/- 0.03 3.16 +/- 0.16 0.69 +/- 0.05 1.32 +/- 0.17 13.71 +/- 0.90

7-8 1.10 0.42 0.62 11.22 2.79 +/- 0.05 0.16 +/- 0.03 3.16 +/- 0.18 0.70 +/- 0.05 1.32 +/- 0.15 11.77 +/- 0.79

8-9 1.09 0.39 0.65 10.89 2.69 +/- 0.20 0.13 +/- 0.03 3.44 +/- 0.20 0.66 +/- 0.05 1.12 +/- 0.17 11.72 +/- 0.86

9-10 1.11 0.40 0.64 10.70 2.47 +/- 0.15 0.12 +/- 0.03 3.14 +/- 0.17 0.70 +/- 0.04 1.35 +/- 0.15 11.77 +/- 0.74

10-11 1.12 0.42 0.62 10.30 2.32 +/- 0.04 0.12 +/- 0.03 3.10 +/- 0.18 0.71 +/- 0.05 1.30 +/- 0.17 11.45 +/- 0.79

10-11

c

8.94 2.24 +/- 0.07

11-12 1.12 0.41 0.64 10.08 2.08 +/- 0.06 0.12 +/- 0.03 2.68 +/- 0.18 0.68 +/- 0.05 1.38 +/- 0.17 11.64 +/- 0.86

12-13 1.11 0.43 0.61 10.43 2.55 +/- 0.04 0.16 +/- 0.03 2.95 +/- 0.15 0.72 +/- 0.04 1.43 +/- 0.13 11.21 +/- 0.69

13-14 1.14 0.46 0.60 10.65 2.21 +/- 0.05 0.15 +/- 0.03 2.65 +/- 0.16 0.68 +/- 0.04 1.63 +/- 0.15 11.81 +/- 0.73

13-14c

8.83 2.14 +/- 0.37

14-15 1.14 0.46 0.60 10.37 1.91 +/- 0.23 0.13 +/- 0.03 2.65 +/- 0.18 0.69 +/- 0.05 1.65 +/- 0.17 11.60 +/- 0.80

15-16 1.19 0.48 0.59 9.98 1.86 +/- 0.12 0.16 +/- 0.04 2.45 +/- 0.17 0.69 +/- 0.05 1.61 +/- 0.17 12.31 +/- 0.87

16-17 1.19 0.49 0.59 10.09 1.87 +/- 0.08 0.16 +/- 0.03 2.44 +/- 0.15 0.68 +/- 0.04 1.70 +/- 0.15 12.24 +/- 0.70

17-18 1.14 0.45 0.60 10.53 1.76 +/- 0.06 0.14 +/- 0.03 2.22 +/- 0.13 0.67 +/- 0.04 1.83 +/- 0.14 11.94 +/- 0.62

18-19 1.15 0.47 0.59 10.42 1.51 +/- 0.11 0.14 +/- 0.03 2.09 +/- 0.16 0.70 +/- 0.05 1.86 +/- 0.18 12.09 +/- 0.81

19-20 1.14 0.47 0.59 9.69 1.46 +/- 0.02 0.13 +/- 0.03 1.81 +/- 0.15 0.72 +/- 0.04 1.97 +/- 0.16 13.00 +/- 0.74

20-21 1.18 0.49 0.59 9.09 1.57 +/- 0.06 0.13 +/- 0.03 1.71 +/- 0.17 0.72 +/- 0.05 1.76 +/- 0.19 13.00 +/- 0.85

20-21c

8.29 1.28 +/- 0.03

20-21c

10.16 1.42 +/- 0.12

21-22 1.13 0.47 0.59 9.68 1.62 +/- 0.08 0.21 +/- 0.04 1.83 +/- 0.17 0.68 +/- 0.05 1.86 +/- 0.18 11.70 +/- 0.84

22-23 1.18 0.49 0.58 10.88 1.47 +/- 0.15 0.24 +/- 0.03 1.94 +/- 0.14 0.69 +/- 0.04 1.74 +/- 0.14 12.57 +/- 0.72

23-24 1.11 0.46 0.58 10.33 1.39 +/- 0.08 0.22 +/- 0.03 2.19 +/- 0.15 0.66 +/- 0.04 1.93 +/- 0.16 13.09 +/- 0.77

23-24c

10.50 1.42 +/- 0.05

24-25 1.14 0.46 0.60 9.93 1.34 +/- 0.05 0.17 +/- 0.03 1.90 +/- 0.16 0.70 +/- 0.05 1.82 +/- 0.18 12.95 +/- 0.85

24-25c

10.70 1.53 +/- 0.03

25-26 1.17 0.50 0.57 9.70 1.14 +/- 0.01 0.14 +/- 0.03 1.58 +/- 0.14 0.78 +/- 0.05 1.82 +/- 0.16 12.83 +/- 0.75

26-27 1.19 0.50 0.58 10.05 0.96 +/- 0.04 0.08 +/- 0.03 1.40 +/- 0.16 0.73 +/- 0.05 1.63 +/- 0.17 12.00 +/- 0.83

26-27c

8.54 1.02 +/- 0.01

27-28 1.18 0.51 0.57 7.91 0.82 +/- 0.02 0.04 +/- 0.03 1.41 +/- 0.17 0.79 +/- 0.05 1.70 +/- 0.19 12.39 +/- 0.87

28-29 1.12 0.49 0.56 7.62 0.66 +/- 0.08 ND 1.15 +/- 0.12 0.77 +/- 0.04 1.61 +/- 0.15 12.51 +/- 0.72

28-29c

10.08 0.77 +/- 0.01

29-30 1.19 0.52 0.56 7.80 0.65 +/- 0.07 ND 1.23 +/- 0.15 0.75 +/- 0.05 1.44 +/- 0.17 12.05 +/- 0.87

30-31 1.21 0.53 0.56 7.90 0.76 +/- 0.01 ND 1.08 +/- 0.15 0.85 +/- 0.05 1.48 +/- 0.19 13.28 +/- 0.89

31-32 1.20 0.53 0.56

a = results determined by alpha spectroscopy method; b = results determined by gamma spectroscopy method; c = replicate analysis

Lc:Cs-137 = 0.03 pCi/g; Lc:Pb-210 = 0.11 pCi/g; Lc:Ra-226 = 0.07 pCi/g; Lc:Th-234 = 0.12 pCi/g; Lc:K-40 = 0.41 pCi/g

[cm, centimeter; g/cm

3

, grams per cubic centimeter; % Mass, percent mass; g OM/g sed, grams of organic matter per grams of sediment; pCi/g, picocuries per gram; ND, not

detected; Lc, critical level]