Spatial Trends and Historical Deposition of Polychlorinated Biphenyls in Canadian Midlatitude and Arctic Lake Sediments
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- 作者：Derek C. G. Muir ; Alex Omelchenko ; Norbert P. Grift ; Dan A. Savoie ; W. Lyle Lockhart ; Paul Wilkinson ; and Gregg J. Brunskill
- 刊名：Environmental Science & Technology
- 出版年：1996
- 出版时间：December 1996
- 年：1996
- 卷：30
- 期：12
- 页码：3609 - 3617
- 全文大小：418K
- 年卷期：v.30,no.12(December 1996)
- ISSN：1520-5851
文摘
A study of PCB concentrations and fluxes in lakesediments was conducted to test the "global fractionation" hypothesis that deposition of semivolatileorganics will decline while more volatile congenerswill be enriched in polar regions. Sediment coreswere collected from 11 remote lakes in Canada rangingfrom 49
N to 82 N and were dated using excess210Pb and137Cs. Sediment extractswere analyzed forup to 90 PCB congeners by capillary GC-ECD withconfirmation by GC/high-resolution MS. Total PCB(
PCB) concentrations in surface slices rangedfrom 2.4 to 39 ng g-1 (dry wt) and showed nolatitudinaltrend. Fluxes (ng m-2yr-1) and inventories of PCBas well as total tetra- to octachlorobiphenylsdeclined with increasing north latitude while thosefor di/trichlorobiphenyls showed no latitudinal trend.Theproportion of di/trichloro congeners of PCB alsoincreased significantly with latitude, while total octachlorobiphenyls declined. Maximum PCB concentrations were observed in subsurface slices datingto the 1960-1970s in most lakes except those in thehigh Arctic, where maxima were generally insurface slices. The onset of elevated PCBdepositionwas delayed in the high Arctic (1950-1960s) relativeto the midlatitude and sub-Arctic lakes (1930-1940s).The high proportions of lower chlorinated congenersand the delayed appearance of PCBs areconsistentwith predictions of the global fractionationmodel.
N to 82 N and were dated using excess210Pb and137Cs. Sediment extractswere analyzed forup to 90 PCB congeners by capillary GC-ECD withconfirmation by GC/high-resolution MS. Total PCB(PCB) concentrations in surface slices rangedfrom 2.4 to 39 ng g-1 (dry wt) and showed nolatitudinaltrend. Fluxes (ng m-2yr-1) and inventories of PCBas well as total tetra- to octachlorobiphenylsdeclined with increasing north latitude while thosefor di/trichlorobiphenyls showed no latitudinal trend.Theproportion of di/trichloro congeners of PCB alsoincreased significantly with latitude, while total octachlorobiphenyls declined. Maximum PCB concentrations were observed in subsurface slices datingto the 1960-1970s in most lakes except those in thehigh Arctic, where maxima were generally insurface slices. The onset of elevated PCBdepositionwas delayed in the high Arctic (1950-1960s) relativeto the midlatitude and sub-Arctic lakes (1930-1940s).The high proportions of lower chlorinated congenersand the delayed appearance of PCBs areconsistentwith predictions of the global fractionationmodel.