Sharon A. Fitzgerald 20210622 spreadsheet https://doi.org/10.5066/P920L16R Specific activities of cesium-137 (half life = 30.17 years), lead-210 (half life = 22.3 years), radium-226 (half life = 1,600 years), thorium-234 (half life = 24.1 days), and potassium-40 (half life = 1.277 billion years) in disintegrations per minute per gram (dpm/g) were determined for the Lake Lanier cores. The laboratory errors (plus or minus) and the critical levels are included for each sample. The purpose of determining cesium-137 activities is to provide a time marker for the main activity peak which is commonly dated to 1964, the peak of above-ground nuclear bomb testing. The presence or absence of cesium-137 activity was also used to determine if sediment was deposited during the period when above-ground testing occurred (approximately from 1950 to 1963) although cesium-137 is often measurable in younger sediment due to delayed fallout and mixing within the sediment and in older sediment due to mixing. Lead-210 activities are used to calculate sedimentation rates based on excess activities which are calculated as the total lead-210 activity minus the supported activity (equal to radium-226 activity once secular equilibrium has been reached). Thorium-234 can be used for sedimentation rates on a several-month scale. Potassium-40 can be used to track clay content in sediments. 20180521 20180525 observed Complete None planned -84.05710 -84.02206 34.17545 34.14577 World ISO 19115 Topic Category inlandWaters USGS Thesaurus radiometric dating cesium-137 lead-210 radium-226 thorium-234 potassium-40 USGS Metadata Identifier USGS:5f49215182ce4c3d122b2a80 Common geographic areas Georgia Lake Sidney Lanier Gwinnett County None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Sharon A. Fitzgerald U.S. Geological Survey Research Hydrologist mailing and physical

3916 Sunset Ridge Road

Raleigh North Carolina 27607 US 919.571.4020 919.571.4041 safitzge@usgs.gov The laboratory error (plus or minus) and the critical levels are reported for all samples. All values fall within expected ranges. There are no data omissions or duplications. A total of 85 samples from 10 lake coring sites were analysed for radioisotope activities of cesium-137, lead-210, radium-226, thorium-234, and potassium-40. Dried sediment samples were analyzed for radionuclide activities by standard gamma-ray spectrometry (Cutshall and Larsen, 1986) at the USGS St. Petersburg Coastal and Marine Science Center radioisotope laboratory. Weighed samples were sealed in airtight polypropylene containers for approximately four weeks to achieve secular equilibrium between the parent isotope, radium-226 and its daughter isotope, radon-222. Samples were counted for two to three days in containers with geometries that were matched to pre-determined calibration standards. Decays were counted for 36 to 72 hours on a planar-style, low energy, high-purity germanium, gamma-ray spectrometer (Canberra Industries, Inc., http://www.canberra.com/). The following radioisotopes with their corresponding photopeak energies in kiloelectron volts (keV): Cs-137 (661.6 keV), Pb-210 (46.5 keV), Pb-214 (295.7 and 352.5 keV; proxies for Ra-226), Th-234 (63.3 keV), and K-40 (1640.8 keV). Detector efficiency was determined with International Atomic Energy Agency (IAEA) RGU-1 reference material, standard photopeak intensity, and self-absorption using a U-238 sealed source (Cutshall and others, 1983). Sample decay rates were corrected for detection efficiency and decay-corrected to the sample collection date. The statistical counting error and the critical level which is the detection level (McCurdy and others, 2008) are reported. 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. Cutshall, N.H., and Larsen, I.L., 1986, Calibration of a portable intrinsic Ge gamma-ray detector using point sources and testing for field applications: Health Physics, v. 51, no. 1, p. 53-59. [Also available at https://dx.doi.org/10.1097/00004032-198607000-00004.] Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210Pb in sediment samples-Self-absorption corrections: Nuclear Instruments and Methods in Physics Research, v. 206, nos. 1-2, p. 309-312. [Also available at https://dx.doi.org/10.1016/0167-5087(83)91273-5.] 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. 20200601 Lake.Lanier.St.Pete.Radchem.csv Comma Separated Value (CSV) file containing activities, errors, and critical levels for five radioisotopes (Cesium-137, Lead-210, Radium-226, Thorium-234, and Potassium-40) in 85 samples from 10 cores collected in lake Lanier in May 2018. Producer Defined Station number A unique number identifying the station Producer Defined '340919084014301 '341017084024201 Station name A unique name identifying the station Producer Defined A unique name identifying the station Sample date The collection date of the sample Producer Defined 5/21/2018 5/25/2018 Sample time The collection time of the sample Producer Defined "0900 "1415 Sample identification An abbreviated station name and depth interval for the sample in centimeters Producer Defined LI1 = Lake Island Cove core 1 LI2 = Lake Island Cove core 2 SF1 = Shadburn Ferry Cove 1 SF2 = Shadburn Ferry Cove 2 LV1 = Lakeview Cove core 1 LV2 = Lakeview Cove core 2 SC1 = Shoal Creek Channel core 1 SC2 = Shoal Creek Channel core 2 SC3 = Shoal Creek Channel core 3 CC = Chattahoochee Channel Midpoint depth (cm) The depth from the sediment/water interface of the midpoint of the sample interval in centimeters Producer Defined 1.0 76.0 Sample weight (g) The weight of the sample in grams Producer Defined 3.4 50.0 Cs-137 activity (dpm/g) The cesium-137 activity in disintegrations per minute per gram Producer Defined ND No data Producer defined 0.17 4.43 Cs-137 error +/- (dpm/g) The counting error (plus or minus) of cesium-137 activity in disintegrations per minute per gram Producer Defined ND No data Producer defined 0.04 0.26 Cs-137 critical level (dpm/g) The critical level of cesium-137 activity in disintegrations per minute per gram Producer Defined ND No data Producer defined 0.06 ND Pb-210 activity (dpm/g) The lead-210 activity in disintegrations per minute per gram Producer Defined 1.85 25.61 Pb-210 error +/- (dpm/g) The counting error (plus or minus) of lead-210 activity in disintegrations per minute per gram Producer Defined 0.27 1.34 Pb-210 critical level (dpm/g) The critical level of lead-210 activity in disintegrations per minute per gram Producer Defined 0.21 0.74 Ra-226 activity (dpm/g) The radium-226 activity in disintegrations per minute per gram Producer Defined 1.61 4.72 Ra-226 error +/- (dpm/g) The counting error (plus or minus) of radium-226 activity in disintegrations per minute per gram Producer Defined 0.07 0.26 Ra-226 critical level (dpm/g) The critical level of radium-226 activity in disintegrations per minute per gram Producer Defined 0.13 0.24 Th-234 activity (dpm/g) The thorium-234 activity in disintegrations per minute per gram Producer Defined 1.79 4.61 Th-234 error +/- (dpm/g) The counting error (plus or minus) of thorium-234 activity in disintegrations per minute per gram Producer Defined 0.25 1.04 Th-234 critical level (dpm/g) The critical level of thorium-234 activity in disintegrations per minute per gram Producer Defined 0.31 0.78 K-40 activity (dpm/g) The potassium-40 activity in disintegrations per minute per gram Producer Defined 18.04 64.13 K-40 error +/- (dpm/g) The counting error (plus or minus) of potassium-40 activity in disintegrations per minute per gram Producer Defined 0.96 3.25 K-40 critical level (dpm/g) The critical level of potassium-40 activity in disintegrations per minute per gram Producer Defined 0.65 1.34 GS ScienceBase U.S. Geological Survey mailing address

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Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P920L16R None 20210622 Jeffrey W Riley U.S. Geological Survey, Southeast Region Ecologist mailing address

1770 Corporate Drive Suite 500

Norcross GA 30093 US 678-924-6682 678-924-6710 jriley@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999