Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1998
Publication Date: N/A
An extensive study of air, rain, and surface water concentrations of twenty currently used pesticides, organochlorine pesticides and three degradation products was conducted during the Summer of 1996 in the Patuxent River watershed. Air and rain were collected at three locations and water was collected at four representative locations in different areas sof the river. Pesticide concentrations in water from an earlier study in 1995 combined with usage information from the Patuxent watershed indicate that a significant source of pesticides is located in the upper watershed area in Prince George's and Anne Arundel counties. Pesticide concentrations were compared with river flow and estimated use patterns in the watershed. Atrazine, 6-amino-2-chloro-4-isopropylamino-s-triazine (CIAT), simazine, metolachlor, and chlorpyrifos were consistently detected with maximum concentrations of 3000, 800, 2700, 70, and 190 ng/L, respectively. Concentrations were highest in the upper watershed, an area where 70% of pesticide usage occurs, and decreased with distance down the river. Dilution appears to be the main factor leading to the decrease in atrazine concentrations down the river. The expanded study conducted in 1996 will be used to more carefully determine the spatial and temporal variability in pesticide fluxes from runoff and atmospheric deposition to the entire watershed area and to describe the effects of tidal dilution on the fate of pesticides in this Chesapeake Bay tributary.