SS4.03 Factors Controlling the Bioavailability and Bioaccumulation of Inorganic and Organic Chemicals into Aquatic Food Chains
Date: Friday, June 14, 2002
Time: 9:15:00 AM
Location: Carson B
 
ChenCY, Dartmouth College, Hanover, USA, celia.chen@dartmouth.edu
Folt, C, L, Dartmouth College, Hanover, USA, carol.folt@dartmouth.edu
 
BIODILUTION AND TROPHIC DILUTION OF HG AND AS IN AQUATIC FOOD WEBS
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Productivity and biomass are known to affect the trophic transfer of organic contaminants but similar relationships have not been investigated for metal contaminants. We investigated metal bioaccumulation and trophic transfer of Hg and As in: (1) 20 lakes in the Northeast U.S., representing a broad range of chemical and physical characteristics; and (2) the food web of a single metal contaminated lake (Upper Mystic Lake, MA) over time. Across the range of lakes, we found that Hg concentrations in the particulate fraction (0.4-47 um) and the small (47-202 um) and large (>202 um) zooplankton fractions decreased with increased abundances in each fraction (biodilution). We also found a significant decrease in the Hg burdens of consumers with an increase in biomass of their prey (trophic dilution). No parallel significant relationships were found for As. Across seasons within a single lake, Hg and As concentrations in phytoplankton decreased with increasing algal biomass and concentrations of both metals in zooplankton increased as their abundance decreased. These findings have important implications for predicting the transfer of metal contaminants in aquatic food webs.