Davies Cheryl M, Ferguson Christobel M, Kaucner Christine, Krogh Martin, Altavilla Nanda, Deere Daniel A, Ashbolt Nicholas J
Centre for Water and Waste Technology, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
Appl Environ Microbiol. 2004 Feb;70(2):1151-9. doi: 10.1128/AEM.70.2.1151-1159.2004.
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 degrees and 10 degrees ) 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 degrees slope) to up to 10(4.5) oocysts from unvegetated soil (55-mm h(-1), 30-min event on 10 degrees 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.
在完整土块（1500×900×300毫米）上进行人工降雨期间，研究了隐孢子虫卵囊从粪便堆中的扩散和初始迁移情况。向接种了约10⁷个卵囊的人工粪便堆所在的土壤地块施加了55毫米/小时、持续30分钟以及25毫米/小时、持续180分钟的降雨。土壤地块被一分为二，一侧无植被，另一侧保留自然植被覆盖。对降雨强度和持续时间、植被状况以及坡度（5度和10度）的每种组合都进行了两次评估。一般来说，与植被覆盖的土壤相比，裸土产生的径流量增加了五倍（P<0.05），并且尽管变化很大，但通过植被覆盖的土块发生的入渗明显更多（P<0.05）。径流量、降雨事件条件（强度和持续时间）、植被状况、坡度及其相互作用显著影响径流中卵囊的负荷。地表径流在1米距离内输送的卵囊数量从植被覆盖的壤土中10⁰.²个（25毫米/小时、180分钟降雨事件，坡度10度）到无植被土壤中高达10⁴.⁵个（55毫米/小时、30分钟降雨事件，坡度10度）不等。粪便堆下坡的表层土壤样本中，无植被地块的卵囊浓度明显高于有植被地块。基于这些结果，在未来评估隐孢子虫的迁移以及管理饮用水流域内靠近溪流的牲畜放牧产生的病原体负荷时，需要考虑地表土壤植被覆盖以及坡度和降雨径流情况。
