†Department of Environmental Science and Technology, University of Maryland at College Park, College Park, Maryland 20742, United States.
‡USDA-ARS Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, Beltsville, Maryland 20705, United States.
Environ Sci Technol. 2015 Jul 7;49(13):7860-9. doi: 10.1021/acs.est.5b01095. Epub 2015 Jun 8.
Understanding and quantifying microbial release from manure is a precondition to estimation and management of microbial water quality. The objectives of this work were to determine the effects of rainfall intensity and surface slope on the release of Escherichia coli, enterococci, total coliforms, and dissolved chloride from solid dairy manure and to assess the performance of the one-parametric exponential model and the two-parametric Bradford-Schijven model when simulating the observed release. A controlled-intensity rainfall simulator induced 1 h of release in runoff/leachate partitioning boxes at three rainfall intensities (30, 60, and 90 mm h(-1)) and two surface slopes (5% and 20%). Bacterial concentrations in initial release were more than 1 order of magnitude lower than their starting concentrations in manure. As bacteria were released, they were partitioned into runoff and leachate at similar concentrations, but in different volumes, depending on slope. Bacterial release occurred in two stages that corresponded to mechanisms associated with release of manure liquid- and solid-phases. Parameters of the two models fitted to the bacterial release dependencies on rainfall depth were not significantly affected by rainfall intensity or slope. Based on model performance tests, the Bradford-Schijven model is recommended for simulating bacterial release from solid manure.
了解和量化粪便中微生物的释放是评估和管理微生物水质的前提条件。本研究的目的是确定降雨强度和地表坡度对大肠杆菌、肠球菌、总大肠菌群和溶解氯从固态奶牛粪便中释放的影响，并评估单参数指数模型和双参数布拉德福德-希夫文模型在模拟观测到的释放时的性能。在径流/淋滤分配箱中，使用控制强度降雨模拟器在三种降雨强度（30、60 和 90 mm h(-1)) 和两种地表坡度（5%和 20%）下诱导了 1 小时的释放。初始释放中的细菌浓度比粪便中的起始浓度低 1 个数量级以上。随着细菌的释放，它们以相似的浓度分配到径流和淋出液中，但取决于坡度，体积不同。细菌释放发生在两个阶段，这与粪便液相与固相间释放的机制相对应。拟合细菌释放对降雨深度的依赖关系的两个模型的参数不受降雨强度或坡度的显著影响。基于模型性能测试，建议使用布拉德福德-希夫文模型来模拟固态粪便中细菌的释放。
