PCBs in the Hudson River - Lecture #1

Background

• The aquatic environment: Lacustrine (salinity < 1 ppt), estuarine (1< salinity < 32 ppt) and ocean (salinity > 32 ppt) regions.
• Types of aquatic pollution:
  • Nontoxic, but a problem in large amounts (e.g. excess nutrients from sewage [nitrate, phosphate] cause eutrophication in local waters).
  • toxics - substances with specific deleterious physiological effects. These are either naturally occurring substances normally found only at very low levels (e.g. metals such as lead and mercury); or novel compounds (typically organic in nature) produced for industrial/ agricultural purposes.
• Polychlorinated biphenyls ( PCBs) are an example of an organic toxin in the freshwater environment. The PCBs were used in electrical equipment (mainly capacitors and transformers) by General Electric, a company with large plants in the upper Hudson River. Their structure is composed of 2 benzene rings substituted with varying numbers of Chlorine atoms (Fig. 1) . These chemicals were sold under the trade name of Arochlor. The different Arochlors are themselves mixtures of PCBs and can be separated readily by gas chromatography (Fig. 2). The production of PCBs peaked around 1970 and the dominant Arochlor sold also changed with time (Fig. 3) .
• Important aspect of PCB environmental chemistry is the fact that it is non-polar. This makes them hydrophobic (= lipophillic) so that they stick to solid surfaces in water or dissolve directly into the lipid components of organisms. Reasons for concern about PCBs in the environment: 1) Direct effect on human health through external contact with this carcinogen; and 2) Effect on upper trophic levels (mainly carnivores) that are subjected to much higher concentrations than those in the ambient water through the process of bioaccumulation. This effects reproductive success of fish and birds and can high levels can be passed to humans that eat affected fish. The stripped bass fishery of the Hudson River has been and remains closed for this reason.
• The tendency for bioaccumulation varies among the PCBs depending on chlorination number (Fig. 4). Bioaccumulation can increase levels of PCBs in the fatty tissue of aquatic organisms more than a million times over that in the surrounding waters (Fig. 5 and Fig. 6).

History of PCB inputs to the upper Hudson River

• PCB use at 2 capacitor plants near Great Falls, NY began in 1947 and 1952 (see map, Fig. 7). The 3 major Arochlors used were 1254, then 1242, and finally 1016.
• Purposeful discharges of PCBs to the river from two capacitor plants began about 1951/ 52 and increased substantially in the mid-60s. Discharges peaked in late 60s and early 70s. Purposeful discharges stopped in the mid-70s.
• In 1973, the Ft. Edward Dam was removed. This released a large amount of PCB laden sediments downstream in the following years.
• In 1991, continued monitoring indicated a dramatic increase in unfiltered Hudson River PCB levels in the upper River. This increase was eventually attributed to a break in a structure associated with the manufacturing facility that had apparently collected a large reservoir of PCBs over many years.
• In 1994, it was discovered that PCBs were also reaching the upper Hudson from the grounds of one of the capacitor plants via infiltration through fissures in the surrounding bedrock. This material was largely Arochlor 1242 (Ports, pers. comm.). Subsequent monitoring at the Hudson Falls site also has identified large underground concentrations of both Arochlor 1242 and 1254 under the capacitor plant (Sloan, pers. comm.).