Environmental Engineering Reference
In-Depth Information
environment from other sources—they can be released into
the atmosphere through burning, and reach aquatic systems
in rainfall. Large quantities of PAHs are also released directly
into the water by chemicals leaching from creosote-treated
wood that is used for bulkheads and docks in shallow water.
There was an interesting case in which an unfortunate female
herring laid her eggs on a creosote bulkhead in California,
and all the eggs were highly abnormal or dead. This particular
bulkhead was over forty years old and releasing far less creo-
sote than it did when it was new, but it still was lethal to all the
embryos, as Carol Vines and coinvestigators at University of
California, Davis found. PAHs also are found in runoff from
asphalt-paved surfaces. Parking lots and roads may be sealed
with PAH-containing coal-tar sealants, and, especially after
the paving has recently been treated, large amounts of PAHs
leach out into runoff whenever it rains.
PAHs are emitted into the air when fossil fuels are burned.
They come down into the ocean in precipitation, and can affect
marine life. Corals are particularly sensitive to these aerosol
particles, which contain soot (carbon with attached PAHs) and
sulfates from fossil fuels.
What are the major sources of oil in the ocean?
Petroleum hydrocarbons (including both linear compounds
and PAHs) have been a long-standing problem in the marine
environment. There is great public concern about oil spills and
the resultant shoreline fouling and deaths of large numbers
of marine birds and mammals. Oil spills can be spectacular
and do a considerable amount of damage; the most obvious
effects being seen in marine birds and mammals that live at
the surface or must come up to the surface to breathe, while
other marine organisms lower in the water may suffer chronic
effects. Since oil spreads as a thin layer on the surface, spills
can pollute large areas and represent serious environmental
hazards. The major source of accidental oil input into seas is
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