Environmental Engineering Reference
In-Depth Information
were from the urban Duwamish Waterway (16%) and Everett
Harbor (12%), while sole from other areas had only 0 to 5.5%
incidence of tumors. Sediment PAH concentration was corre-
lated with tumors.
Oil is also associated with changes in behavior. Juvenile
coho salmon exposed to the water soluble fraction of crude
oil showed reduced swimming activity, which was affected
by the concentration and time of exposure. When fish were
put into clean water, normal activity was restored within
eight hours. Awantha Dissanayake and colleagues compared
cellular (immune function), physiological (heart activity),
and behavioral (feeding) responses in shore crabs collected
from a PAH-contaminated site and two cleaner sites and
also looked at responses of crabs exposed in the laboratory
to pyrene, a four-ring PAH. While no significant cellular or
physiological impacts were seen in contaminated crabs, feed-
ing was impaired: when given a cockle (bivalve), the field and
laboratory-exposed crabs took longer to handle and break the
shells. Therefore, behavior was more sensitive than the cellu-
lar and physiological responses.
How long do effects of oil spills last?
Many of the major spills had long-term consequences because
the oil came into estuaries and marshes. The persistence of oil
is influenced by several factors, such as water solubility, weath-
ering rate, and sediment grain size. The residues may last for
decades and continue to affect biological functions including
behavior, development, genetics, growth, feeding, and repro-
duction. Long-term effects have been studied after spills, and
they vary depending on the nature of the oil, the temperature,
and the nature of the area of the spill. After a spill, most of the
oil undergoes a weathering process. However, in marshes or
sandy beaches oil can sink down to depths where it persists
for decades in the absence of oxygen. The major effects of a
rather small oil spill (190,000 gallons of number two fuel oil)
Search WWH ::
Custom Search