Phytoplankton pigments and their alteration products in macrozooplankton feces were characterized by high-performance liquid chromatography. Fecal material was obtained from animals collected in the Southern California Bight, USA. Different patterns of fecal pigment composition were observed for 2 size classes of macrozooplankton grazers. Fecal material produced by copepoddominated assemblages contained intact phytoplankton carotenoids. Feces produced by 3 relatively large grazers (2 salp species and a pelagc crab) contained polar carotenoid products, tentatively identified as the ester hydrolysis products of peridinin, fucoxanthin, and 19'-hexanoyloxyfucoxanthin (characteristic carotenoids of major phytoplankton taxa). Degradation of chlorophyll a apparently occurred within the guts of both size classes of macrozooplankton, although some intact chlorophyll a was found in all fecal pellet collections. It is proposed that the difference in carotenoid alterations mediated by the 2 size classes of macrozooplankton grazers is related to differences in gut esterases and to the transit time of ingested material through the guts of the animals. Hydrolysis products of the estersubstituted carotenoids could provide a pigment 'signal' indicating the presence of feces produced by large macrozooplankton grazers in sediment trap collections.

A one-year in situ bioremediation pilot study was implemented in January 1992 at a site contaminated with polynuclear aromatic hydrocarbons, benzene, ethyl benzene, toluene, and xylenes from former manufactured gas plant operations. The objective of the study was to evaluate the effectiveness of in situ bioremediation on high molecular weight hydrocarbons under site conditions. The pilot study involved injecting treated groundwater amended with nutrients and oxygen (in the form of hydrogen peroxide) into the subsurface via an injection well, extracting groundwater through a downgradient extraction well, and periodically monitoring the system using monitoring wells and soil borings. Results indicate that the site hydrogeology, the high concentrations of target and non-target organics, and the presence of pure-phase coal tar in the subsurface limit the cost-effective application of in situ bioremediation at this site.

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