title: Fate and transport of copper-based crop protectants in plasticulture runoff and the impact of sedimentation as a best management practice.
abstract: The fate and distribution of copper-based crop protectants, applied to plasticulture tomato fields to protect against disease, were investigated in a greenhouse-scale simulation of farming conditions in a coastal environment. Following rainfall, 99% of the applied copper was found to remain on the fields sorbed to the soil and plants; most of the soil-bound copper was found sorbed to the top 2.5 cm of soil between the plasticulture rows. Of the copper leaving the agricultural fields, 82% was found in the runoff with the majority, 74%. sorbed to the suspended solids. The remaining copper, 18%, leached through the soil and entered the groundwater with 10% in the dissolved phase and 8% sorbed to suspended solids. Although only 1% copper was found to leave the field, this was sufficient to cause high copper concentrations (average 2102+/-433 microg/L total copper and 189+/-139 microg/L dissolved copper) in the runoff. Copper concentrations in groundwater samples were also high (average 312+/-198 microg/L total copper and 216+/-99 microg/L dissolved copper). Sedimentation, a best management practice for reducing copper loadings. was found to reduce the total copper concentrations in runoff by 90% to a concentration of 245+/-127 microg/L; however, dissolved copper concentrations remained stable, averaging 139+/-55 microg/L. Total copper concentrations were significantly reduced by the effective removal of suspended solids with sorbed copper.
authors.affiliation: Civil and Environmental Engineering, Virginia Tech, Blacksburg 24061-0246, USA. dang@vt.edu
authors.forename: D L
authors.initials: DL
authors.lastname: Gallagher
authors.forename: K M
authors.initials: KM
authors.lastname: Johnston
authors.forename: A M
authors.initials: AM
authors.lastname: Dietrich
mesh_terms: D000327:Adsorption; D000383:Agriculture; D016573:Agrochemicals / Q000378:metabolism / Q000494:pharmacology*; D019985:Benchmarking / Q000379:methods; D011232:Chemical Precipitation; D003300:Copper / Q000378:metabolism / Q000494:pharmacology*; D004780:Environment, Controlled; D004784:Environmental Monitoring / Q000379:methods*; D005618:Fresh Water / Q000032:analysis / Q000737:chemistry*; D018551:Solanum lycopersicum / Q000378:metabolism; D010575:Pesticides / Q000378:metabolism / Q000494:pharmacology*; D010969:Plastics; D011891:Rain; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis; D012995:Solubility; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D016573:Agrochemicals; D010575:Pesticides; D010969:Plastics; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D003300:Copper