Abstract

Pathogenic enteric viruses and bacteria tend to occur in higher concentrations and survive longer in aquatic sediments than suspended in the water column. Re-suspension of these organisms can result in a significant degradation of overlying water quality. Additionally, the re-suspension of microbial pathogens in artificial irrigation canals could endanger the consumption of fresh and ready-to-eat produce. Irrigation water has been implicated in numerous fresh produce outbreaks over the last 30 years. This study aimed to quantify the proportions of bacterial and viral re-suspension from sediment in a recirculating flume with varying velocities. MS2 coliphage and Escherichia coli were found to re-suspend at rates that were not significantly different, despite organism size differences. However, E. coli re-suspension rates from sand and clay were significantly different. This suggests that likely sediment-associated particles were recovered with the organisms attached. Similar re-suspension rates are hypothesized to be due to the dynamics of sediment transport, rather than that of the organisms themselves. This study also indicated that the re-suspension of sediment at very low velocities (e.g., less than 10 cm/s), could impact the microbiological quality of the overlaying water. Results from this study conclude that sediment could be a viable mechanism for irrigation water contamination.

摘要

病原性肠道病毒和细菌倾向于以较高浓度发生，并且在水生沉积物中的存活时间比悬浮在水柱中的更长。这些生物的重新悬浮会导致上层水质的严重下降。此外，微生物病原体在人工灌溉渠中的重新悬浮可能危及新鲜和即食产品的消费。在过去的30年中，灌溉水与许多新鲜农产品的爆发有关。这项研究旨在量化速度变化的循环水槽中来自沉积物的细菌和病毒重悬的比例。尽管有机体大小存在差异，但发现MS2噬菌体和大肠杆菌以没有明显差异的速率重新悬浮。然而，沙子和粘土中的大肠杆菌重悬率显着不同。这表明与附着的生物体一起回收了可能的沉积物相关颗粒。假设类似的再悬浮速率是由于沉积物迁移的动态，而不是由于生物本身的动态。该研究还表明，以非常低的速度（例如，小于10 cm / s）重新沉积沉积物可能会影响覆盖水的微生物质量。这项研究的结果得出结论，沉积物可能是灌溉水污染的可行机制。