Diagnostic indicators of biological community stress using benthic community analysis to tease apart impacts of organic enrichment and toxicity: An experiment in McMurdo Sound. Charles Peterson, University of North Carolina at Chapel Hill. Communities of benthic invertebrates are widely used to monitor and evaluate biological impacts of pollution in the marine environment because their sessile lifestyles, longevity, functional diversity, well-known taxonomy, and ecological significance render this system an ideal ecological template on which biological consequences are imprinted. Benthic communities have been used successfully in environmental assessments for convincing demonstrations that impacts of pollution are readily detectable at the level of family and phylum for macrofaunal invertebrates.

Our project is designed to test the hypothesis that indices of abundance and production for individual phyla of macrofauna and/or meiofauna can be used as independent diagnostics to tease apart the typically confounded impacts of these two separate classes of marine pollution. We will test the hypothesis that annelid worms and nematodes are enhanced by modest organic loading and arthropods and echinoderms are depressed preferentially by modest exposure to toxic contaminants (trace metals). This hypothesis will be tested near McMurdo Station because

• its relatively constant environment allows experimental work to proceed on the seafloor without compromise by confounding disturbances;
• previous benthic studies at this site have revealed significant confounded patterns of sediment contamination and benthic community degradation; and
• low rates of natural bioremediation in cold polar oceans make study of pollution impacts especially critical at high latitudes.

Our first objective will be to establish a field experiment near McMurdo Station where the investigators will manipulate organic loading and trace metal concentrations in sediment within colonization trays to test whether the separate taxa respond independently to the classes of pollution. Treatments will also include access of larger mobile predators and time for community development to assess whether biological interactions within the ecosystem with the diagnostic capability of the indices of pollution stress. Second, we will complete a rigorous review and meta-analysis of all available data sets on effects of pollution on marine invertebrate communities to test the hypothesis using the wealth of pre-existing information from monitoring discharges, oil spills, and previous experimentation. (EO-302-O)

Measurement of combustion effluent aerosols from the Amundsen–Scott South Pole Station. Anthony Hansen, Magee Scientific Company. Anthropogenic activities in Antarctica have the potential of producing both contemporaneous and long-term environmental impacts on the nearly pristine surroundings. One of these impacts arises from the emission of "black" or "elemental" carbonaceous aerosols from the exhaust of diesel-powered generators and vehicles used to support antarctic operations. When deposited on the snow and ice cover, this pollutant may be preserved indefinitely. Its high optical absorption will alter the surface albedo and the radiative properties of surface cover. Its ability to promote catalytically certain chemical reactions may lead to modifications of snow and ice chemistry. Its absorbed content of fuel-derived organic species, such as polycyclic aromatic hydrocarbons and other toxics, may harm marginal biota and near coastal stations.

Previous work showed that extremely small, but detectable, concentrations of black carbon aerosol are brought to the Amundsen–Scott South Pole Station in the background atmosphere in amounts consistent with models of long-range transport; however, the program that made this determination terminated in 1990. A 1986 study of surface snow and ice showed a clear plume of soot downwind of the station. We will install more modern equipment both upwind and downwind of the South Pole Station to re-establish the background aerosol measurements and to provide a direct assessment of the station's emissions. The results of our work will contribute to determining the station's environmental impact resulting from combustion-derived emissions. This information may be used to design mitigation and abatement strategies. The upwind data will contribute to the global monitoring record and to assessments of the global circulation of anthropogenic emissions capable of influencing atmospheric optics and chemistry. (EO-314-O)