title: Transport of Cryptosporidium parvum oocysts through vegetated buffer strips and estimated filtration efficiency.
abstract: Vegetated buffer strips were evaluated for their ability to remove waterborne Cryptosporidium parvum from surface and shallow subsurface flow during simulated rainfall rates of 15 or 40 mm/h for 4 h. Log(10) reductions for spiked C. parvum oocysts ranged from 1.0 to 3.1 per m of vegetated buffer, with buffers set at 5 to 20% slope, 85 to 99% fescue cover, soil textures of either silty clay (19:47:34 sand-silt-clay), loam (45:37:18), or sandy loam (70:25:5), and bulk densities of between 0.6 to 1.7 g/cm(3). Vegetated buffers constructed with sandy loam or higher soil bulk densities were less effective at removing waterborne C. parvum (1- to 2-log(10) reduction/m) compared to buffers constructed with silty clay or loam or at lower bulk densities (2- to 3-log(10) reduction/m). The effect of slope on filtration efficiency was conditional on soil texture and soil bulk density. Based on these results, a vegetated buffer strip comprised of similar soils at a slope of <or=20% and a length of >or=3 m should function to remove >or=99.9% of C. parvum oocysts from agricultural runoff generated during events involving mild to moderate precipitation.
authors.affiliation: Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California-Davis, Tulare, California 93274, USA. ratwill@vmtrc.ucdavis.edu
authors.forename: Edward R
authors.initials: ER
authors.lastname: Atwill
authors.forename: Lingling
authors.initials: L
authors.lastname: Hou
authors.forename: Betsy M
authors.initials: BM
authors.lastname: Karle
authors.forename: Thomas
authors.initials: T
authors.lastname: Harter
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Tate
authors.forename: Randy A
authors.initials: RA
authors.lastname: Dahlgren
mesh_terms: D000818:Animals; D002021:Buffers; D016785:Cryptosporidium parvum / Q000502:physiology*; D005374:Filtration; D033661:Oocysts / Q000502:physiology*; D011891:Rain
chemical_list: D002021:Buffers