Environmental Engineering Reference
In-Depth Information
stranded in 2004-2009 in the Pearl River Delta in China. Seventy fi ve percent of the
DDT residue was p , p
-DDT, suggesting fresh releases of DDT. The authors note
that DDT is still being used in China for control of malaria.
In summary, there are few reports of DDT concentrations in dolphins or porpoises
important to the Newport Bay region. Those above are for animals sampled else-
where in the world. Although they demonstrate the ability of several species of
dolphins to accumulate DDT and its degradation products, the actual concentrations
may not refl ect what would occur in animals residing on the California coast.
Similar to harbor seals and California sea lions, toxic effects from DDT in the subject
dolphins have yet to be conclusively demonstrated via controlled studies.
DDT and Whales . Although whales (baleen or toothed) are not likely to spend time
in Newport Bay, to be conservative, we summarize the pertinent publications involv-
ing DDT and the whale species most likely to, at least, briefl y visit the area. Over
the years, many studies have reported on the contaminants present in the blubber
of baleen whales, including gray and minke whales. For instance, in gray whales
( E. gibbosus ) Wolman and Wilson ( 1970 ) measured DDT concentrations as high as
680 ppb in some 23 animals collected between 1968 and 1969, and Schafer et al.
( 1984 ) reported a concentration of 470 ppb in a single animal sampled in 1976. In
1994 , Varanasi et al. reported the concentrations of DDE in the tissues and stomach
contents from 22 gray whales stranded between 1988 and 1991 along the coast from
Kodiak Island, Alaska, to San Francisco, California. Gray whales have the unique
habit of fi lter feeding along benthic sediments. Therefore, they are potentially capa-
ble of ingesting sediment-sorbed organic contaminants. Mean concentrations, and
the ranges, measured in blubber were: DDT, 68 ± 22 ppb (1-370 ppb); DDD,
76 ± 24 ppb (1-470 ppb); and DDE, 310 ± 96 ppb (9-2,100 ppb). In liver, residues
were predictably reduced: DDT, 1 ± 0.4 ppb (0.4-3 ppb); DDD, 23 ± 5 ppb
(0.6-52 ppb); and DDE, 100 ± 28 ppb (7-280 ppb). Most interestingly, they found
no signifi cant differences in the concentrations from whales collected in the more
pristine Kodiak Island/Washington outer coastal areas versus those collected in the
more impacted areas of Puget Sound, Washington, and San Francisco.
Tilbury et al. ( 2002 ) sampled gray whales from a subsistence harvest in the Arctic
during the fall of 1994 and compared their DDT concentrations (per lipid weight)
with those of stranded gray whales from the same general collection area. They dis-
covered signifi cant differences in the harvested versus stranded whale blubber con-
centrations of males (200 ± 38 ppb versus 39,000 ± 23,000 ppb), females (360 ± 66 ppb
versus 2,800 ± 1,000 ppb) and juveniles (330 ± 53 ppb versus 11,000 ± 4,300 ppb),
respectively. The consistently higher concentrations in stranded animals may
indicate their possible cause of death. However, tissue degradation of dead and
potentially decaying animals limits the usefulness of such a comparison.
In minke whales, Schafer et al. ( 1984 ) reported a DDT concentration of 587 ppm
from a single animal stranded off southern California. However, this high concentration
appears to be linked to an urbanized area, as 29 minke whales sampled off the South
African coast ranged only as high as 820 ppb (Henry and Best 1983 ), while another
37 sampled in Antarctica ranged from 10 to 140 ppb (Tanabe et al. 1986 ).
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