Stormwater management practices (SMPs) rely on infiltration and adsorption capabilities of soil and vegetative cover to mitigate the harmful impacts of contaminants in stormwater runoff, including potentially toxic elements (PTEs). Under chemical equilibrium conditions, the soil-water distribution coefficient (K_d) quantifies the relationship between the solid and aqueous phase PTE concentrations, and thus the PTE removal efficiency and mobility through the SMP soil layers during the infiltration process. The SMP loading ratio (LR), the ratio of the drainage area to the SMP infiltration area, combined with runoff concentration determines SMP mass loading and is also expected to impact PTE transport. In this study, a simulation model was developed to investigate PTE breakthrough and build-up in SMP media, considering the impacts of K_d and LR. Eight PTEs were simulated (Cl⁻, Cr, Fe, Zn, Cu, As, Cd, and Pb), and Cl⁻ was the only PTE that showed high mobility and reached the groundwater table (e.g., ~ 1 year for breakthrough). Conversely, other PTEs were effectively immobilized in the top ~60 cm of soil for a simulated lifespan of 20 years. Soil and porewater contaminant indices, as indicators of SMP lifespan, were estimated based on the ratio of PTE porewater and soil concentrations after 20 years to published standards, suggesting the following order of environmental significance (most concern to least): Cl⁻ > Cr > As > Pb > Fe > Cu > Cd > Zn. After 20 years of simulated use, only Cl⁻ pore water concentrations at the groundwater table exceeded regulatory values, with porewater contamination index values of 4 to 7.5. Chloride also exceeded the surficial media soil contamination index, as did As and Cr, though these exceedences were largely associated with media background concentrations. Generally, higher LR and K_d contributed to higher accumulation of PTEs in top layers; however, simulations showed that the combination of low LR and high K_d may result in lower PTE accumulation in the media, such that the PTE concentration in soil may decrease in deeper layers. In these scenarios, a notable fraction of PTE load was adsorbed on top layers and considerably lower PTE concentrations reached the lower layers. Sensitivity analysis revealed that dispersion, infiltration rate, and kinetically-limited sorption did not impact the PTE accumulation and mobility to a practical extent. The results from this simulation may be adapted to various environmental conditions to enhance the design and maintenance of SMPs.

雨水管理实践（SMP）依靠土壤和植物覆盖层的渗透和吸附能力来减轻雨水径流中污染物（包括潜在的有毒元素）的有害影响。在化学平衡条件下，水土分配系数（K _d）量化了固相和水相PTE浓度之间的关系，从而量化了渗透过程中PTE去除效率和通过SMP土壤层的迁移率。SMP负载比（LR），排水面积与SMP渗透面积之比以及径流浓度共同决定了SMP的质量负载，也有望影响PTE的运输。在这项研究中，考虑到K _d和LR的影响，开发了一个仿真模型来研究PTE在SMP介质中的突破和积累。八页的PTE进行了模拟（CL ^- ，铬，铁，锌，铜，砷，镉，和Pb），和Cl ^-是唯一显示出高流动性并达到地下水位（例如，突破约1年）的PTE。相反，将其他PTE有效地固定在约60 cm的土壤顶部，模拟寿命为20年。土壤孔隙水污染物指标，为SMP寿命的指标，估计基于PTE孔隙水和土壤中的浓度在20年后出版的标准比例，提示的环保意义如下顺序（最关注至少）：氯^- > CR> As> Pb> Fe> Cu> Cd> Zn 经过20多年的模拟使用的，只有氯^-地下水位的孔隙水浓度超过了规定值，孔隙水污染指数值为4至7.5。氯离子也超过了表面介质的土壤污染指数，砷和铬也超过了表面污染物，尽管这些超出很大程度上与介质的背景浓度有关。通常，较高的LR和K _d有助于顶层中PTE的积累；然而，模拟表明低LR和高K _d的组合可能会导致培养基中PTE的积累降低，从而土壤中PTE的浓度可能会在更深的一层下降。在这些情况下，PTE负载的显着部分被吸附在顶层，而较低的PTE浓度到达了较低的层。敏感性分析表明，分散度，渗透率和动力学受限的吸附作用实际上并未影响PTE的积累和迁移。该模拟的结果可以适应各种环境条件，以增强SMP的设计和维护。