Cycles of nutrient elements, hydrophobic organic compounds, and metals in Crystal Lake. Role of particle-mediated processes in regulation
Measurements of the chemical composition and fluxes of particulate matter were used to assess the particle-mediated cycling of selected nutrient elements, hydrophobic organic compounds, and metals in Crystal Lake, located in north central Wisconsin. The absence of surface water input simplified the analysis of in-lake cycles. Sediment incorporation and accumulation fluxes were calculated on the basis of an assumption of negligible sediment focusing. Removal of 210Pb was rapid with negligible recycling, and 210Po was partly recycled in the water column. The nutrient elements (C, N, P, and Si) contained in deposited particles were partly recycled ( 50\%) into the water column, but most of the P recycled was subsequently redeposited through interaction with Fe(III) formed near the sediment-water interface. Hydrophobic organic compounds such as polychlorinated biphenyls (PCBs) were also removed rapidly to the sediment-water interface by particle deposition but apparently returned partly to the water column during particle incorporation into surface sediments. Although PCBs were partly returned to the sediments by redeposition, recycling from bottom sediments increased the residence time of PCBs in the water column. Differences among chemical constituents in particle-mediated fluxes were regulated by differences in biogeochemical processes.
American Chemical Society