Effluents derived from a municipal wastewater treatment plant were used for virus filtration/retention experiments by using a horizontal laboratory filter. Filtration tests were performed to examine how soil geochemical heterogeneity and fracture patterns affected the transport of viruses in groundwater in order to model the influence of reductive perturbations in ionic strength (IS) during wastewater filtration. Although perturbations of IS and velocity are known to result in resuspension of colloids, we found that the effect of soil geochemical heterogeneity can produce strong and instantaneous virus releases in fractured aquifers, likely an internal additional source of viruses. Sixteen limestone slabs were packed in a PVC box filter at the Bari Laboratory (South Italy) to replicate wastewater filtration throughout a fractured medium similar to the Bari carbonate aquifer. Terra rossa, which is an aggregate of sand, silt and clay, was unevenly spread on the surface of each limestone slab within the filter. Since the mineralogical composition of terra rossa includes iron (hematite, magnetite, and goethite) oxides, the soil exhibited localized unfavorable colloid/collector interactions for attachment. In contrast, soil-free parts of the fracture surfaces maintained favorable colloid/collector interactions. We found in our experiments that the lowering of IS due to the reduction of water salt content, which could occur during runoff injections after rainfall, might be sufficient to cause strong detachment of viruses from fracture surfaces, allowing further migration into the groundwater. The model in this work can predict the count and pathways of released viruses in groundwater fractures under soil geochemical heterogeneity and originated by reductions of IS, by using analytical solutions.

中文翻译：

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响应离子强度的扰动，裂缝流中的病毒大量释放：过滤/保留测试和模型

通过使用水平实验室过滤器，将市政污水处理厂产生的废水用于病毒过滤/保留实验。进行了过滤测试，以检查土壤地球化学异质性和破裂模式如何影响地下水中病毒的迁移，从而模拟废水过滤过程中离子强度（IS）的还原扰动的影响。尽管已知IS和速度的扰动会导致胶体重新悬浮，但我们发现土壤地球化学异质性的影响可在破裂的含水层中产生强而瞬时的病毒释放，这很可能是病毒的内部其他来源。Terra rossa是沙子，淤泥和粘土的聚集体，不均匀地分布在过滤器内每个石灰石平板的表面上。由于terra rossa的矿物学组成包括铁（赤铁矿，磁铁矿和针铁矿）氧化物，土壤表现出局部不利的胶体/收集器相互作用。相反，断裂表面的无土部分保持了良好的胶体/收集器相互作用。我们在实验中发现，由于降雨后径流注入过程中可能发生的水盐含量降低而导致的IS降低可能足以导致病毒从裂缝表面强烈分离，从而允许进一步迁移到地下水中。通过使用分析解决方案，该模型可以预测土壤地球化学异质性下地下水裂缝中释放的病毒的数量和途径，并通过分析解决方案来减少IS的产生。