The University of Toledo Department of Environmental Sciences, Toledo, OH 43606, USA.
Sci Total Environ. 2012 Sep 1;433:273-80. doi: 10.1016/j.scitotenv.2012.06.021. Epub 2012 Jul 15.
The land-application of Class B biosolids is tightly regulated to allow for natural attenuation of co-applied pathogens. Since many agricultural fields that receive biosolids are artificially drained through subsurface tiles, it is possible that under scenarios of excessive drainage associated with heavy rainfall events, co-applied pathogens might be carried offsite to contaminate nearby surface waters. To address this concern, we used genetic as well as traditional methods to investigate the impact of rainfall on the offsite drainage of Escherichia coli from agricultural fields during biosolids application. Water samples from field drain tiles and a reference field (no biosolids applied) were collected pre-, during and post-biosolids application, while samples of applied biosolids were collected on site during application. The samples were analyzed for E. coli-density and community- and isolate-fingerprinting to assess the genetic link between E. coli in drainage water and those co-applied with biosolids. In contrast to E. coli densities present in the reference field drainage, our results revealed that post-application drainage water collected from biosolids treated fields contained significantly higher E. coli densities following heavy rainfall events, as compared to light rainfall events. Also, in contrast to the reference field, heavy rainfall correlated significantly with increased similarity of E. coli community fingerprints occurring in biosolids to those draining from treated field. Fingerprinting of individual E. coli revealed a high similarity (>94%) between some isolates collected from biosolids and post-application drainage water. Using a combination of enumeration and genetic typing methods, we show that heavy rainfall following biosolids application to agricultural fields induced the offsite transport of biosolids-associated E. coli, potentially compromising the quality of water draining through the watershed.
土地应用 B 级生物固体受到严格监管，以允许共同应用的病原体自然衰减。由于接收生物固体的许多农业领域通过地下瓦片进行人工排水，因此在与大雨事件相关的过度排水的情况下，共同应用的病原体可能会被携带到场外，污染附近的地表水。为了解决这个问题，我们使用遗传和传统方法来研究降雨对生物固体应用期间农业领域场外大肠杆菌排水的影响。在生物固体应用之前、期间和之后，从田间排水瓦和参考字段（未应用生物固体）收集水样，而在应用过程中在现场收集应用的生物固体样本。对水样进行大肠杆菌密度和群落和分离物指纹分析，以评估排水水中大肠杆菌与与生物固体共同应用的大肠杆菌之间的遗传联系。与参考字段排水中的大肠杆菌密度相比，我们的结果表明，与轻雨事件相比，大雨事件后从生物固体处理过的田地收集的应用后排水水中的大肠杆菌密度显着更高。此外，与参考字段相比，大雨与生物固体中大肠杆菌群落指纹的相似性增加显着相关，这些指纹与从处理过的田地中排水的指纹相似。对单个大肠杆菌的指纹分析显示，从生物固体和应用后排水中收集的一些分离株之间具有高度相似性（>94%）。我们使用计数和遗传分型方法的组合表明，生物固体应用于农业领域后的大雨引起了生物固体相关大肠杆菌的场外运输，可能会损害通过流域排水的水质。
