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Atmospheric transport of pesticides in the Sacramento, California, metropolitan area, 1996-1997

Weekly composite, bulk air was sampled with respect to wind speed and direction from January 1996 through December 1997 in one urban and two agricultural locations in Sacramento County, California. The sampling sites were located along a north-south transect, the dominant directions of the prevailing winds. The samples were analyzed for a variety of current-use pesticides, including dormant orchard spray insecticides and rice herbicides. A variety of pesticides were detected throughout the year, predominantly chlorpyrifos, diazinon, and trifluralin. The data obtained during the winter and spring suggest that some pesticides used in agricultural areas become airborne and may be transported into the urban area. Confirmation of this drift is difficult, however, because these three predominant pesticides, as well as other detected pesticides, also are heavily used in the urban environment. The spring data clearly show that molinate and thiobencarb, two herbicides used only in rice production, do drift into the urban environment.

Water-Resources Investigations Report↗

Quantity and quality of urban storm runoff in the Irondequoit Creek basin near Rochester, New York: Part 2,.Quality of storm runoff and atmospheric deposition, rainfall-runoff-quality modeling and potential of wetlands for sediment and nutrient retention

Water quality data collected at 17 sites in urbanized and rural parts of the 438 sq km Irondequoit Creek basin from July 1980 through August 1981 were used to compute annual loads of eight selected constituents. Of the total annual loads of these constituents, 50 to 70% was transported to Irondequoit Bay during a 3.5-month period from late January to early May. Of six mixed-land-use subbasins, the two most highly urbanized had the highest loads of all constituents. Of the four sites representing single land uses, the high density residential site and the housing construction site had the highest loads of all constituents except cadmium. A rainfall-runoff model was used to predict quantity and quality of storm runoff leaving one commercial site, two residential sites, and a large mixed-land-use subbasin. Predicted volume and peak discharges were within 10 to 30% of the measured values; predicted runoff loads of most constituents were within 40 to 60% of measured values. Stormflow modification in the Irondequoit Creek wetlands by two hypothetical control structures was simulated. Results indicate that outflow from the upper wetland could be decreased and stormflows dispersed to a greater part of the upper wetland to increase retention of suspended solids and associated chemical constituents.

New York↗