Although polychlorinated biphenyls (PCBs) are no longer manufactured, they are still entering the environment. In some compartments of the environment, PCB concentrations are a serious concern. This is especially true in compartments which accumulate PCBs, and in food items consumed by humans and wildlife. Also, there are situations in which management decisions require rapid, sensitive, accurate measurements, which can be made in real time under field conditions. Methods to use an enzyme-linked immunosorbent assay (ELISA) for PCBs were developed and applied to sediments and fish muscle homogenates collected from the Great Lakes. The extraction methods developed can be applied in the field with non-hazardous solvents, in the absence of sophisticated laboratory equipment. The method detection limit for PCBs in dimethyl sulfoxide (DMSO) extracts of sediment was 0.9 mg/kg. For PCBs in isopropanol extracts of fish tissue, the method detection limit was 0.6 mg/kg. The resolution of the ELISA was 0.83 mg/kg at 1.1 mg/kg and 1.6 mg/kg at 1.7 mg/kg, for sediment and fish tissue, respectively.

The ocean plays a central role in the global carbon cycle being by far the largest active reservoir. Atmospheric CO2 level depends on the CO2 concentration in the ocean surface layer, which is relatively low compared to mean oceanic values due to biological and physical carbon pumps. Although the ocean may take up much of the carbon released by the increased burning of fossil fuels, this capacity is limited because of the chemical buffering and a mismatch in time scales (oceanic mixing is much slower than anthropogenic perturbations).