Affiliation:
1. Centre for Water and Waste Technology, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052
2. Sydney Catchment Authority, Penrith, New South Wales 2751, Australia
Abstract
ABSTRACT
The dispersion and initial transport of
Cryptosporidium
oocysts from fecal pats were investigated during artificial rainfall events on intact soil blocks (1,500 by 900 by 300 mm). Rainfall events of 55 mm h
−1
for 30 min and 25 mm h
−1
for 180 min were applied to soil plots with artificial fecal pats seeded with approximately 10
7
oocysts. The soil plots were divided in two, with one side devoid of vegetation and the other left with natural vegetation cover. Each combination of event intensity and duration, vegetation status, and degree of slope (5° and 10°) was evaluated twice. Generally, a fivefold increase (
P
< 0.05) in runoff volume was generated on bare soil compared to vegetated soil, and significantly more infiltration, although highly variable, occurred through the vegetated soil blocks (
P
< 0.05). Runoff volume, event conditions (intensity and duration), vegetation status, degree of slope, and their interactions significantly affected the load of oocysts in the runoff. Surface runoff transported from 10
0.2
oocysts from vegetated loam soil (25-mm h
−1
, 180-min event on 10° slope) to up to 10
4.5
oocysts from unvegetated soil (55-mm h
−1
, 30-min event on 10° slope) over a 1-m distance. Surface soil samples downhill of the fecal pat contained significantly higher concentrations of oocysts on devegetated blocks than on vegetated blocks. Based on these results, there is a need to account for surface soil vegetation coverage as well as slope and rainfall runoff in future assessments of
Cryptosporidium
transport and when managing pathogen loads from stock grazing near streams within drinking water watersheds.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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