Department of Civil and Environmental Engineering, The University of Southern California, Kaprielian Hall 224B, 3620 South Vermont Ave., Los Angeles, CA 90089, USA.
Sci Total Environ. 2020 Jul 20;727:138363. doi: 10.1016/j.scitotenv.2020.138363. Epub 2020 Apr 10.
Assessing the health risks associated with emerging contaminants in groundwater systems is a complex issue that has been receiving increased attention in indirect potable reuse applications. Among several emerging contaminants, our study focuses on developing a numerical model that aims to compute the transport characteristics of Bisphenol A (BPA) in a 3D spatially heterogeneous aquifer under uncertainty. Traditional approaches that characterize the health risk of BPA to humans rely on the monotonic dose-response (MDR) relationship with a regulatory dose limit. Recent public health studies indicate that BPA can cause endocrine-related health effects in specific low dose ranges, which requires the consideration of the non-monotonic dose-response (NMDR) model. This work investigates the impact of different BPA DR models (i.e., monotonic vs. non-monotonic) on the resilience of the aquifer against BPA contamination in the presence of hydrogeological heterogeneity. For the resilience estimation, a systematic stochastic methodology linking risk characterization to aquifer resilience is established. Our results show the importance of the interplay between the DR models and aquifer heterogeneity on controlling the uncertainty of the resilience loss R (d) at a specified environmentally sensitive target. In the increased level of aquifer heterogeneity, the uncertainty bounds are higher for R estimated through the NMDR model as opposed to the MDR model. Moreover, R is controlled by η (-), the ratio of the volumetric flow rate at the source zone to the average flow rate at the background aquifer. In a risk management perspective, the consideration of the NMDR model needs to be emphasized due to its impact on the uncertainty of R. A critical case is when the land use of a contamination site indicates a large number of the vulnerable population to endocrine-related health effects. In this case, η as an indicator of aquifer resilience can reduce the uncertainty of R.
评估地下水系统中新兴污染物相关的健康风险是一个复杂的问题，在间接饮用水再利用应用中受到了越来越多的关注。在几种新兴污染物中，我们的研究重点是开发一个数值模型，旨在计算在不确定性下 3D 空间非均质含水层中双酚 A（BPA）的输运特性。传统的方法是根据 BPA 对人类健康的危害，依赖于具有监管剂量限制的单调剂量反应（MDR）关系。最近的公共卫生研究表明，BPA 在特定低剂量范围内会引起与内分泌相关的健康影响，这需要考虑非单调剂量反应（NMDR）模型。这项工作研究了不同 BPA 剂量反应（即单调与非单调）模型对含水层抵御存在水文地质非均质性情况下 BPA 污染的恢复力的影响。对于恢复力估计，建立了一种将风险特征与含水层恢复力联系起来的系统随机方法。我们的结果表明，在控制特定环境敏感目标的恢复力损失 R(d)的不确定性方面，DR 模型和含水层非均质性之间的相互作用非常重要。在含水层非均质性增加的情况下，通过 NMDR 模型估计的 R 的不确定性界限高于通过 MDR 模型估计的 R。此外，R 由 η(-)控制，即源区体积流速与背景含水层平均流速的比值。从风险管理的角度来看，需要强调考虑 NMDR 模型，因为它会影响 R 的不确定性。在污染场地的土地利用表明大量易感人群存在与内分泌相关的健康影响的情况下，这是一个关键案例。在这种情况下，作为含水层恢复力指标的 η 可以降低 R 的不确定性。
