Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu, 215123, People's Republic of China; Department of Environmental Science, University of Liverpool, Brownlow Hill, Liverpool, L69 7ZX, UK.
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
Water Res. 2020 Apr 1;172:115478. doi: 10.1016/j.watres.2020.115478. Epub 2020 Jan 9.
Environmental risk assessment (ERA) increasingly relies on speciation modeling of bioavailability. Heavy metals are the most prevalent pollutants globally, and dissolved organic matter (DOM) plays an important role in speciation and bioavailability of heavy metals. Due to the variation of DOM properties in natural aquatic systems, improvements to the standard one-size-fits-all approach to modeling metal-DOM interactions are needed for ERA. In this study, we investigate variations in DOM and lead (Pb)-DOM binding in Lake Tai (Taihu), a large, impacted lake in eastern China that is characterized by a complex drainage network and is an important water resource at a regional level, and we assess implications of our findings within the context of ERA needs. In our study, DOM in water samples collected from across the 2,400 km area of Taihu was characterized using three-dimensional excitation-emission matrix and synchronous fluorescence spectroscopy spectra, the latter being used to calculate conditional stability constants for metal binding. Parallel factor analysis and peak picking were used to assess contributions of protein- and humic-like components of DOM, and fluorescence indices indicative of diagenetic processes were calculated. These quantities calculated from spectroscopic studies, in addition to water quality parameters, were analyzed by bivariate and multivariate analysis. Results show that different DOM components are highly variable across different regions of Taihu, and bivariate and multivariate analyses confirm that water quality and DOM characterization parameters are strongly interrelated. This reflects the different inputs, diagenetic and transport processes across the large expanse of Taihu. We find that the conditional stability constant of Pb-DOM binding is strongly affected by the water chemical properties and composition of DOM, though the conditional stability constant is not itself a parameter that differentiates lake water properties in different regions of the lake. The variability of DOM composition and Pb-DOM binding strength across Taihu is consistent with prior findings that a one-size-fits-all approach to metal-DOM binding may lead to inaccuracies in commonly used speciation models, and therefore such generalized approaches need improvement for regional-level ERA in complex watersheds. The approach taken here to obtain site-specific metal-DOM conditional stability constants for use in increasing the accuracy of speciation modeling is fit-for-purpose for ERA applications at regional levels because the approach is relatively simple, inexpensive, and amenable to high throughput analysis.
环境风险评估（ERA）越来越依赖于生物有效性的形态建模。重金属是全球最普遍的污染物，而溶解有机质（DOM）在重金属的形态和生物有效性中起着重要作用。由于天然水系统中 DOM 性质的变化，需要改进标准的一刀切方法来对金属-DOM 相互作用进行建模，以满足 ERA 的要求。在这项研究中，我们调查了中国东部大型受影响湖泊太湖中 DOM 和铅（Pb）-DOM 结合的变化情况，该湖泊具有复杂的排水网络，是区域水平上的重要水资源，我们评估了我们的研究结果在 ERA 需求背景下的意义。在我们的研究中，使用三维激发-发射矩阵和同步荧光光谱对从太湖 2400 公里范围内采集的水样中的 DOM 进行了表征，后者用于计算金属结合的条件稳定常数。平行因子分析和峰提取用于评估 DOM 中蛋白质和腐殖质样成分的贡献，以及指示成岩过程的荧光指数。从光谱研究中计算出的这些数量，以及水质参数，通过二元和多元分析进行了分析。结果表明，不同区域的 DOM 成分差异很大，二元和多元分析证实了水质和 DOM 特征参数之间存在很强的相关性。这反映了太湖广阔范围内不同的输入、成岩和传输过程。我们发现，Pb-DOM 结合的条件稳定常数受水化学性质和 DOM 组成的强烈影响，尽管条件稳定常数本身并不是区分湖泊不同区域水质的参数。太湖 DOM 组成和 Pb-DOM 结合强度的变异性与先前的研究结果一致，即金属-DOM 结合的一刀切方法可能导致常用形态模型中的不准确，因此需要改进此类通用方法，以满足复杂流域的区域水平 ERA 的要求。这里采用的获取特定于站点的金属-DOM 条件稳定常数的方法，用于提高形态建模的准确性，适用于区域水平的 ERA 应用，因为该方法相对简单、廉价且易于进行高通量分析。
