Effects of microbial activity on aquatic pollutants.

Bacteria and fungi present in estuarine and marine water and sediment accomplish significant degradation of crude oil, refined oils, polychlorinated biphenyls, and organomercurials, with the rate and extent of degradation varying with species, geographic source, temperature, and other biologic and environmental parameters. Our biodegradation studies have been extended to determine if physical weathering and/or microbial degradation of oil by microorganisms present in Chesapeake Bay water and sediment produces potentially carcinogenic substances. Water and sediment from an area in Chesapeake Bay that receives heavy input of oil and from a relatively nonpolluted site have been assayed for mutagenic ability by use of the Ames method, which is a bacterial assay and is highly sensitive. Preliminary findings indicate the presence of mutagenic substances in samples collected from the polluted site. Extracts of oil subjected to microbial degradation under controlled laboratory conditions did not yield detectable mutagenic activity. In situ studies are in progress.