Dj. Gregor et al., THE HISTORICAL RESIDUE TREND OF PCBS IN THE AGASSIZ ICE CAP, ELLESMERE ISLAND, CANADA, Science of the total environment, 161, 1995, pp. 117-126
Current detailed measurements of contaminant deposition cannot provide
a historical perspective except through long-term monitoring programs
. In the Arctic, ice caps provide an alternative to lake sediments, in
that the annual snow layers reflect atmospheric deposition. As a resu
lt of the remoteness of the ice cap and the limited summer melt, annua
l layers undergo little chemical change, especially after the first su
mmer season, and therefore provide a well-defined historical record. I
nitial work was undertaken at the Agassiz Ice Cap (80 degrees 49'50''
N, 72 degrees 56'30'' W) beginning in 1986, but a major effort was und
ertaken in 1993, during which snow samples covering 30 years were take
n from a snow pit. Large volume snow samples were obtained for the det
ermination of PCB congeners. Mean Sigma PCB deposition to the ice cap
ranged from 930 ng/m(2)/year in the winter of 1967-1968 to a minimum o
f 91 ng/m(2)/year in 1980-1981. Since 1980-1981, deposition has again
increased to a local maximum of 848 ng/m(2)/year (in 1989-1990). Tile
mean deposition for the 30 years of record was 406 ng/m(2)/year, with
no evidence of a consistent long-term trend.