title: Pesticide and nitrate transport in an agriculturally influenced stream in Indiana.
abstract: Agrochemicals can be transported from agricultural fields into streams where they might have adverse effects on water quality and ecosystems. Three enrichment experiments were conducted in a central Indiana stream to quantify pesticide and nitrogen transport dynamics. In an enrichment experiment, a compound solution is added at a constant rate into a stream to increase compound background concentration. A conservative tracer (e.g., bromide) is added to determine discharge. Water and sediment samples are taken at several locations downstream to measure uptake metrics. We assessed transport of nitrate, atrazine, metolachlor, and carbaryl through direct measurement of uptake length (Sw), uptake velocity (Vf), and areal uptake (U). Swmeasures the distance traveled by a nutrient along the stream reach. Vfmeasures the velocity a nutrient moves from the water column to immobilization sites. U represents the amount of nutrient immobilized in an area of streambed per unit of time. Swvaried less than one order of magnitude across pesticides. The highest Swfor atrazine suggests greater transport to downstream ecosystems. Across compounds, pesticide Swwas longest in August relative to October and July. Vfvaried less than one order of magnitude across pesticides with the highest Vffor metolachlor. U varied three orders of magnitude across pesticides with the highest U associate with sediment-bound carbaryl. Increasing nitrate Swsuggests a lower nitrate demand of biota in this stream. Overall, pesticide transport was best predicted by compound solubility which can complement and improve models of pesticide abundance used by water quality programs and risk assessments.
authors.affiliation: Department of Biology, Ball State University, 2000 W. University Ave. CL121, Muncie, IN, USA. delias@bsu.edu.
authors.forename: Daniel
authors.identifier: http://orcid.org/0000-0002-4257-6804
authors.initials: D
authors.lastname: Elias
authors.affiliation: Department of Biology, Ball State University, 2000 W. University Ave. CL121, Muncie, IN, USA.
authors.forename: Melody J
authors.initials: MJ
authors.lastname: Bernot
mesh_terms: D000383:Agriculture; D016573:Agrochemicals; D001280:Atrazine; D017753:Ecosystem; D004784:Environmental Monitoring; D007196:Indiana; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen; D010575:Pesticides / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D060753:Water Quality
chemical_list: D016573:Agrochemicals; D009566:Nitrates; D010575:Pesticides; D014874:Water Pollutants, Chemical; D009584:Nitrogen; D001280:Atrazine
keywords: Areal uptake; Atrazine; Carbaryl; Metolachlor; Uptake length; Uptake velocity