Environ. Sci. Technol. 1984, 18, 935-937
Academic Press: New York, 1965; p 238.
Taymaz, K.; Williams, D. T. Znt. J. Environ. Anal. Chem. 1979, 6 , 289. Gordon, G.; Kieffer, R. G.; Rosenblatt, D. H. Prog. Znorg. Chem. 1972,15, 201. Masschelein, W. J. "Chlorine Dioxide: Chemistry and Environmental Impact of Oxychlorine Compounds"; Ann Arbor Science: Ann Arbor, MI, 1979. Ames, B. N. Science (Washington,D.C.) 1983,221,1256. Hine, J . "Physical Organic Chemistry";McGraw-Hill: New York, 1962; p 332. Cram, D. J. "Fundamentals of Carbanion Chemistry";
Received for review December 23, 1983. Revised manuscript received May 14,1984. Accepted June 12,1984. Although the research described in this article has been funded wholly by the US. Environmental Protection Agency under Assistance Agreement R807455 and R809695 to the University of Minnesota, it has not been subjected to the Agency's required peer and administrative review and, therefore, does not necessarily reflect the view of the Agency, and no official endorsement should be inferred.
DDT Has Declined More Than PCBs in Eastern Canadian Seals during the 1970s Rlchard F. Addison," Paul F. Brodie, and Maurice E. Zinck
Marine Ecology Laboratory, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada B2Y 4A2 David E. Sergeant
Arctic Biological Station, Ste. Anne d e Bellevue, Quebec, Canada H9X 3R4
w Concentrations of DDT-group insecticide residues in the blubber of gray seals (Halichoerus g r y p u s ) shot on Sable Is., Nova Scotia, in 1982 were lower than in comparable samples taken in 1974 and 1976; p,p'-DDE represented a greater fraction of the total DDT group in the 1982 samples than in 1974 or 1976. These data are consistent with the availability of DDT group residues having declined during the interval 1976-1982. Concentrations of polychlorinated biphenyl (PCB) residues did not change over this period. Similar trends emerged from a comparison of harp seals (Pagophilus groenlandicus) shot in the Gulf of St. Lawrence in 1971 and in 1982, except that, in this group, a slight reduction in PCB levels occurred over the 11-year interval. Taken together, the data suggest that DDT-group levels are declining significantly in high level predator organisms but that PCB levels are declining less rapidly.
Table I.. Comparisons of Organochlorine Residue Concentration (pg g-l Wet Weight), Age (years), Blubber Thickness (cm), and Lipid Content (% Wet Weight) in Sable Is. Gray Seal (Halichoerus grypus) Mother-Pup Pairs Sampled in 1974, 1976, and 1982 and Analyzed As Described in Text 1974 (n = 5) p,p'-DDE p,p/-DDT CDDT p,p'-DDE as % EDDT PCB age blubber thickness blubber lipid content
Introduction
Organochlorine residue levels in seal blubber vary with the animal's age (I-4), sex (2-4), and condition ( 2 , 4 ) . We have previously established the relationships between these factors and DDT-group insecticide and PCB (polychlorinated biphenyl) levels in male harp seals (Pagophilus groenlandicus) sampled in 1971 from the Gulf of St. Lawrence ( I ) and in female gray seals (Halichoerus gryp u s ) from Sable Is., Nova Scotia, sampled (5)in 1974 and 1976. We now report that in samples taken in 1982 from these two populations, DDT-group levels have fallen appreciably, but PCB levels have not fallen significantly. This is the first clear indication that DDT-group residues in high trophic level marine biota have responded to the DDT ban of the early 1970s. Experimental Section
In 1982, seals were sampled from these populations and were analyzed as described previously ( I , 5 )in some cases by the same analyst using the same equipment as before (6). Selected samples were analyzed by capillary column gas chromatography-mass spectroscopy (GC-MS) using a Finnigan Model 4000 instrument fitted with a 20 m X 0.25 mm fused silica column coated with SE-30 to confirm the structure of PCB peaks and to show the absence of interfering substances such as mirex and toxaphene. El0013-936X/84/0918-0935$01.50/0
p,p'-DDE p,p'-DDT EDDT p,p'-DDE as % CDDT PCB pup stage (range) (5) blubber lipid content
data as means f SD 1982 1976 (n = 8) (n = 6)
Mothers 7.5 f 3.6" 5.7 f 2.0" 5.3 f 2.8" 5.0 f 3.0" 10.7 f 4.9" 12.7 f 6.2" 56.0 i 10.3" 59.7 f 7.0"
2.5 f OBb 1.0 f 0.2b 3.5 f L O b 72.2 f 2.6b
NDd ND 3.7 f 0.3"
11.7 f 4.4' 6.8 f 1.2" 3.7 f 1.1"
15.7 f 5.8" 14.5 f 7.gC 4.8 f 0.7b9C
89.5 f 3.1"
82.3 f 6.2c
91.5 f 3.0°
Pups 4.1 i 1.6" 3.8 f 2.7 i 1.0' 2.3 f 6.8 f 2.6" 6.1 f 60.2 f 1.6" 63.0 f
1.7' 1.2" 2.9" 5.0"
1.5 f 0.6b 0.6 i 0.2* 2.1 f O.Sb 72.3 f 2.1b
ND 1-111
1.9 f 0.7" 11-IV
5.0 f 3.5c 1-111
80.9 f 8.2"
83.2 i 3.0"
87.2 f 12.3"
"Data in the same row not significantly different by t test. bData in the same row differ significantly (P< 0.01) by t test. cData in the same row differ significantly (P < 0.05) by t test. dND, not determined.
uates from Florisil columns were examined before and after dehydrochlorination (6);standards were treated similarly. Comparisons were made by using the parent ion (M+)and easily recognizable chlorinated ions, especially M - 70 fragments. These approaches allowed the confirmation of PCBs and showed the absence of chlorinated hydrocarbons other than the DDT or PCB groups at concentrations above about 0.5 pgg-l wet weight tissue. The 1974 and 1976 gray seal data (5)were recalculated to a wet weight basis and compared to the 1982 data by
0 1984 American Chemical Society
Environ. Sci. Technol., Voi. 18, No. 12, 1984 935
Table 11. Comparisons of Ages (years), Blubber Thickness (cm), and Organochlorine Residue Concentrations (pg0g-l Wet Weight Blubber) in Male Harp Seals (Pagophilus groenlandicus) from the Gulf of St. Lawrence Sampled in 1971 and 1982 As Described in Text’
1971 no. of samples age blubber thickness p,p’-DDE p,p’-DDD p , p ’-DDT
CDDT PCB p,p’-DDE % XDDT
1982
F
22
11
4.9 f 3.2 (1-11) 4.4 f 0.7 (3.5-6.0) 4.2 f 3.6 (1.7-14.5) 0.7 f 0.4 (0.0-1.4) 2.8 f 1.6 (1.0-6.7) 7.7 f 5.4 (3.1-22.6) 7.4 5.9 (2-22) 53.1 f 7.7 (42.567.7)
6.4 f 2.8 (2-12) 5.3 f 0.8 (3.8-6.4) 1.2 f 0.6 (0.382.20) 0.2 f 0.1 (0.1-0.3) 0.3 k 0.1 (0.1-0.5) 1.7 f 0.8 (0.6-3.1) 4.0 f 2.4
*
NSb
