title: Effect of vegetated filter strips on transport and deposition rates ofEscherichia coliin overland flow in the eastern escarpments of the Mau Forest, Njoro River Watershed, Kenya.
abstract: The fate and transport ofEscherichia coli(E. coli) in lotic waters through vegetated filter strips (VFSs) was evaluated in a field model pasture, utilizing VFSMOD Windows along with direct pathogen testing. This study assessed effects of VFS on transport and deposition rates ofE. coliin lotic overland flow waters. The VFS measured 44 m long by 40 m wide, covering an area of 1584 m2and land slope of 15 %. Cowpat was applied onto the model pasture and washed by overland flow into the VFS. The 4-methylumbelliferyl β-D-glucuronide substrate confirmed the identity ofE. coliprior to cowpat application and after isolating them from soil using centrifugation and membrane filtration techniques. Napier grass root system recorded the highest recovery rates ofE. coliat 99.9 % along the length of VFS III. This efficiency reduced significantly (p< 0.05;df= 29) to 95 % in Kikuyu grass and 75 % in Couch grass-Buffer grass. The data demonstrated similarity in transport of manure-borneE. coliand organic carbon (OC) through all the simulated VFS. These results indicated that OC could be used as a true natural tracer of manure-borneE. coli, a pollution indicator organism of lentic and lotic surface waters provided the OC release kinetics from cowpat were similar to that ofE. colikinetics. Thus, efficient filtering to reduceE. coliconcentrations and load in overland flows requires managing combined grass species, agro-pastoral systems models and dispersed or preferential flows to enhance surface water quality standards.
authors.affiliation: Department of Environmental Science, Egerton University, Nakuru, Kenya.
authors.forename: C O
authors.initials: CO
authors.lastname: Olilo
authors.affiliation: Department of Agricultural Engineering Technology, Egerton University, Nakuru, Kenya.
authors.forename: J O
authors.initials: JO
authors.lastname: Onyando
authors.affiliation: Department of Environmental Science, Egerton University, Nakuru, Kenya.
authors.forename: W N
authors.initials: WN
authors.lastname: Moturi
authors.affiliation: Department of Biological Sciences, Egerton University, Nakuru, Kenya.
authors.forename: A W
authors.initials: AW
authors.lastname: Muia
authors.affiliation: Department of Crops and Soil Sciences, Egerton University, Nakuru, Kenya.
authors.forename: P
authors.initials: P
authors.lastname: Ombui
authors.affiliation: Department of Biological Sciences, Masinde Muliro University of Science and Technology, Kakamega, Kenya.
authors.forename: W A
authors.initials: WA
authors.lastname: Shivoga
authors.affiliation: School of Veterinary Medicine, University of California, Davis, Davis, CA, USA.
authors.forename: A F
authors.initials: AF
authors.lastname: Roegner
keywords: Escherichia coli; Fate and transport; Lotic surface water; Mass balance; Micro-biome; Overland flow rate; VFS