|Hetzer, P - UNIV MD|
|Baker, J - UNIV MD|
Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1999
Publication Date: N/A
Technical Abstract: We evaluated the effects of surface-water runoff and sediment deposited from experimental outdoor agricultural plots on four estuarine organisms: the copepod Eurytemora affinis, the amphipod Leptochierus plumulosus, the hard clam Mercenaria mercenaria, and the diatom Thalassiosira psuedonana. Experimental plots consisted of two treatments with four replications per treatment. The first treatments utilized a growing technique used widely throughout the U.S. termed plasticulture, in which raised beds are covered with black polyethylene to control soil temperature, humidity, and weed growth. The second treatment was a new technique in which a hairy vetch, Vicia villosa, was grown on the plot, an then mulched to obtain the same beneficial effects as the plastic. Tomatoes were grown identically (except for mulching methods) in each plot with equivalent pesticide applications. Runoff water was collected approximately twice a month (May-Aug) following pesticide applications and a subsequent rainfall event (worst case) that produced a significant surface-runoff. Dissolved concentrations of analytes (endosulfan I and II, endosulfan sulfate, fenvalerate, esfenvalerate, chlorothalonil, metribuzin, and copper) were quanitified in water and sediment samples collected on site. A subsample was then analyzed immediately prior to the beginning of the bioassays to determine any loss during storage. Standard bioassays were conducted to determine lethal and sublethal effects on the test organisms resulting from pesticide exposure. Additional laboratory studies were conducted to investigate the independent and interactive effects of selected pesticides, and to determine the effects of pulsed-exposures on test organisms.