Coring artifacts and contaminant inventories in lake sediment |
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| Authors: | M Stephenson J Klaverkamp M Motycka C Baron W Schwartz |
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| Institution: | (1) Storage and Disposal Technology Branch, AECL Chalk River Laboratory, Chalk River, Ontario, Canada;(2) Environmental Science Branch, AECL Whiteshell Laboratory, R0E 1L0 Pinawa, Manitoba, Canada;(3) Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, R3T 2N6 Winnipeg, Manitoba, Canada |
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| Abstract: | Sediments of Lake 382, Experimental Lakes Area, Canada, were sampled at six sites using a 5-cm Wildco KB core sampler (KB), a similar device incorporating a ball check valve (BC), and a 0.2 m by 1.2 m flat-faced aluminum freeze core sampler (FC). Cores were sectioned at 1-cm intervals to a depth of 15 cm. Contaminant (210Pb and 137Cs) concentrations (Bq g-1) were measured by gamma spectroscopy, and inventories (Bq cm-2) were calculated following standard methods. Sediments collected using FC, BC and KB had similar contaminant concentrations, however, cores collected by FC and BC had lower estimated inventories than KB cores. Differences between estimates appear to be caused by differences in the water content (WC) of core material. Laboratory studies confirm that FC sediments have higher WC than tube-cored sediment. We hypothesize that ice crystal formation increases the WC of freeze cores, resulting in lower contaminant inventories. Loss of surficial sediment caused by a  bow wave may have a similar effect on BC samples. We conclude that KB core gear is appropriate for sampling sediments to measure contaminant concentrations and inventories in recently deposited sediments. |
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| Keywords: | lake sediments gravity core freeze core coring artifacts contaminant concentration contaminant inventory |
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