Active Sources of PCBs Contribute to Contamination of Delaware River Fish
WEST TRENTON, N.J., June 24 /PRNewswire/ -- Active and historic sources of
PCBs are contributing to the current fish contamination problem in the
Delaware Estuary, according to a report released today by the Delaware River
Basin Commission.
Concern regarding the levels of this class of pollutants in the tissues of
recreationally caught fish has prompted the states of Delaware, New Jersey and
Pennsylvania to issue fish consumption advisories. Lack of comprehensive and
reliable information concerning the sources of PCBs to the estuary and the
associated transport pathways has hindered mitigation of the problem. The
Commission, state environmental agencies and federal agencies have documented
elevated concentrations of PCBs in the river sediments over the last ten
years. This study, which focused on wastewater treatment plants and
tributaries, sought to develop solid information about these entities as
conduits of PCB contamination.
The report indicates that the current fish contamination problem cannot be
attributed solely or predominantly to "historic" sediment contamination
already in the estuary, as many resource managers have believed. Indeed, the
active loading entering the estuary from sewage treatment plants, combined
sewage outflows (CSOs), and tributaries is sufficient, independent of the PCBs
already in estuary sediments, to cause water quality criteria exceedances and
associated fish contamination.
Water samples collected during both dry and wet weather revealed that
wastewater treatment plants and tributaries discharging to the tidal Delaware
River are active and significant sources of PCB. Wastewater treatment plants
and overflows from their collection systems contributed 90% to 95% of the PCBs
during both dry and wet weather sampling surveys. Significantly more PCBs (up
to 60 times) entered the river during wet weather than during dry weather.
Independent of weather conditions, most of the PCBs enter the river between
the Tacony-Palmyra and Walt Whitman Bridges.
These findings suggest that rainfall significantly increases PCB mass loading
to the estuary. The mechanisms presumably are increased resuspension,
erosion, and transport of PCBs associated with contaminated upland sediments
as well as PCBs associated with sewer systems.
The study also demonstrates that, independent of the PCB already present in
estuary sediments, the active loading entering the estuary from sewage
treatment plants, CSOs, and tributaries is indeed enough to degrade water
quality and contaminate fish.
These sources are not themselves generators of PCBs. Rather, they are merely
conduits for PCBs that have been inadvertently or deliberately introduced into
sewage collection systems, eroded from contaminated upland sites, and
transported via overland flow into the collection systems and down through
tributary watersheds.
Sewage treatment plants, in fact, reduce significantly the amount of PCB
entering the estuary, as evidenced by much lower concentrations of PCBs in the
water discharged from the plants compared to that in the wastewater entering
the plants. Presumably, much of the PCBs that enters the treatment plants is
captured in sludge produced by the plants. That sludge in turn is then
redistributed to the environment to an unknown extent.
The study results clearly show that additional steps need to be taken to
mitigate the impact of PCBs on aquatic life and human health. Barriers to a
comprehensive approach exist, however. These include the perception among
both regulators and the public that PCBs are historical pollutants that are no
longer manufactured and are therefore not currently entering the environment,
the use of less sensitive analytical methods that often fail to detect
individual PCBs, and the failure to consider some pathways by which PCBs enter
the Delaware River.
The report also recommends systematic identification of significant upland
sources of PCBs, enhancement of the Commission's mathematical model of the
estuary, and implementation of effective sediment and erosion control
practices.
In releasing this report, the Delaware River Basin Commission hopes to
increase public awareness that PCBs are a current and not a historical threat
to the health of the biota and to users of the estuary, and to encourage
proper disposal of electrical equipment containing PCBs.
The study was jointly funded by the U.S. Environmental Protection Agency,
Regions II & III, and the Delaware River Basin Commission.
SOURCE Delaware River Basin Commission
CO: Delaware River Basin Commission; U.S. Environmental Protection Agency
ST: Pennsylvania, New Jersey, Delaware
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