Latitudinal trends in fluxes and congener patterns of PCBs inferred from lake sediment cores from mid-latitude and Arctic Lakes
- Department of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.
- NOAA, Ann Arbor, MI (United States). Great Lakes Environmental Research Lab.
Sediment cores collected from 9 remote lakes in central and Arctic Canada (49{degree}N to 82{degree}N and from 71{degree} to 136{degree}W) were analyzed for PCBs with the objective of examining latitudinal and temporal trends in deposition. Core slices (1--1.3 cm) were dated with {sup 210}Pb and {sup 137}Cs using the Robbins rapid steady-state mixing model and sediment focusing factors were determined with the aid of soil cores or predictions of historical radionuclide deposition. Slices were freeze-dried, Soxhlet extracted with DCM and chromatographed on Florisil, then analyzed by high resolution GC-ECD with confirmation by GC-HRMS. {Sigma}PCB concentrations in surface sediments were low ranging from 8 to 40 ng{center_dot}g{sup {minus}1} (dry wt) in southern mid-continental sites (49--63{degree}N) to 2 ng{center_dot}g{sup {minus}1} in Lake Hazen, the most northerly location (82{degree}N). Highest concentrations were found in the most recent slices (1980s) of cores from high Arctic lakes (at 75 and 82{degree}N) whereas peak concentrations were reached earlier (in the 1970s) at more southerly locations. Principal components analysis revealed that sediments from high Arctic lakes could be distinguished by greater proportions of lower chlorinated PCBs in comparison with published results for Lakes Ontario and Superior. Focus corrected {Sigma}PCBs fluxes ranged from 305 to 920 ng{center_dot}m{sup 2}{center_dot}yr{sup {minus}1} in the 9 lakes and were negatively correlated with latitude (r{sup 2} = 0.53). Fluxes of Cl{sup 8} CBs had a strong negative correlation with latitude (r2 = 0.88) while Cl{sup 3} CBs showed no latitudinal trend. The results generally support several of the predictions of the cold condensation hypothesis.
- OSTI ID:
- 191325
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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