Subsurface irrigation by recharging shallow phreatic aquifers to raise the water table allows treated wastewater and other marginal water to be used in irrigation, without directly exposing crops to contaminants of emerging concern (CECs). The effects of soil and aquifer properties, environmental hydrological fluxes, irrigation parameters, and CEC biogeochemical reaction parameters, on crop and environmental contamination risks, are studied through numerical modeling. Non-biodegraded CEC solutes leave the agricultural field mostly by lateral discharge within the phreatic zone. The solute mass discharged beneath the simulated domain (potentially into deeper confined groundwater) typically represents the smallest portion of solute fate, but varied by orders of magnitude across scenarios. In contrast, other components of solute fate: the solute mass recovered by the subsurface drains, crop solute uptake, and solute mass discharged laterally within the phreatic zone are larger (in ascending order), but varied across scenarios mostly within one order of magnitude. Furthermore, solute biogeochemical reaction parameters most greatly (by orders of magnitude) affected crop solute uptake and solute discharge into the environment, followed by the hydrogeological parameters, atmospheric fluxes, and finally irrigation parameters. Hence, unfavorable biogeochemical or hydrogeological conditions cannot be mitigated by optimizing irrigation parameters. Although biogeochemical parameters affect only the partitioning of irrigated solute fate across the possible outcomes, hydrogeological parameters may also affect the irrigated solute mass, as more irrigation is needed to maintain target groundwater levels in phreatic aquifers with higher hydraulic conductivities or deeper confining layers. The irrigated solute mass strongly determines contaminant discharge to the environment, but has less effect on crop solute uptake, which is limited by crop water uptake. This study also shows that phreatic zone wastewater irrigation has crop contamination risks that are sensitive to factors different than (near-)surface irrigation techniques, and therefore contributes a meaningful alternative technique for reusing marginal water in irrigation.

中文翻译：

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水生区废水灌溉：污染物归宿的敏感性分析


通过补给浅层含水层来提高地下水位，进行地下灌溉，可以将处理过的废水和其他边际水用于灌溉，而不会直接使作物暴露于新兴污染物 （CEC） 中。通过数值建模研究土壤和含水层特性、环境水文通量、灌溉参数和 CEC 生物地球化学反应参数对作物和环境污染风险的影响。非生物降解的 CEC 溶质主要通过物理区内的横向排放离开农田。在模拟域下方排放的溶质质量（可能排放到更深的密闭地下水中）通常代表溶质命运的最小部分，但在不同情景中会相差几个数量级。相比之下，溶质命运的其他组成部分：地下排水管回收的溶质质量、作物溶质吸收和在物理区内横向排出的溶质质量更大（按升序排列），但不同情景之间的差异大多在一个数量级内。此外，溶质生物地球化学反应参数对作物溶质吸收和溶质排放到环境中的影响最大 （按数量级） 最大，其次是水文地质参数、大气通量，最后是灌溉参数。因此，不利的生物地球化学或水文地质条件不能通过优化灌溉参数来缓解。尽管生物地球化学参数仅影响灌溉溶质在可能结果中的分配，但水文地质参数也可能影响灌溉溶质质量，因为需要更多的灌溉来维持具有较高水力传导率或较深承压层的浸润含水层的目标地下水位。 灌溉溶质质量在很大程度上决定了污染物排放到环境中，但对作物溶质吸收的影响较小，因为作物溶质吸收受到作物水分吸收的限制。这项研究还表明，污水区废水灌溉具有作物污染风险，这些风险对与（近）地表灌溉技术不同的因素很敏感，因此为在灌溉中再利用边际水提供了一种有意义的替代技术。