Zhang Xiaokai, Qin Boqiang, Deng Jianming, Wells Mona
Department of Environmental Science, 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, United Kingdom.
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.
Environ Pollut. 2017 Oct;229:902-910. doi: 10.1016/j.envpol.2017.07.068. Epub 2017 Aug 2.
As the world burden of environmental contamination increases, it is of the utmost importance to develop streamlined approaches to environmental risk assessment in order to prioritize mitigation measures. Whole-cell biosensors or bioreporters and speciation modeling have both become of increasing interest to determine the bioavailability of pollutants, as bioavailability is increasingly in use as an indicator of risk. Herein, we examine whether bioreporter results are able to reflect expectations based on chemical reactivity and speciation modeling, with the hope to extend the research into a wider framework of risk assessment. We study a specific test case concerning the bioavailability of lead (Pb) in aqueous environments containing Pb-complexing ligands. Ligands studied include ethylene diamine tetra-acetic acid (EDTA), meso-2,3 dimercaptosuccinic acid (DMSA), leucine, methionine, cysteine, glutathione, and humic acid (HA), and we also performed experiments using natural water samples from Lake Tai (Taihu), the third largest lake in China. We find that EDTA, DMSA, cysteine, glutathione, and HA amendment significantly reduced Pb bioavailability with increasing ligand concentration according to a log-sigmoid trend. Increasing dissolved organic carbon in Taihu water also had the same effect, whereas leucine and methionine had no notable effect on bioavailability at the concentrations tested. We find that bioreporter results are in accord with the reduction of aqueous Pb that we expect from the relative complexation affinities of the different ligands tested. For EDTA and HA, for which reasonably accurate ionization and complexation constants are known, speciation modeling is in agreement with bioreporter response to within the level of uncertainty recognised as reasonable by the United States Environmental Protection Agency for speciation-based risk assessment applications. These findings represent a first step toward using bioreporter technology to streamline the biological confirmation or validation of speciation modeling for use in environmental risk assessment.
随着全球环境污染负担的增加，开发简化的环境风险评估方法以确定缓解措施的优先级至关重要。全细胞生物传感器或生物报告器以及形态建模对于确定污染物的生物有效性越来越受到关注，因为生物有效性越来越多地被用作风险指标。在此，我们研究生物报告器的结果是否能够反映基于化学反应性和形态建模的预期，希望将该研究扩展到更广泛的风险评估框架中。我们研究了一个关于含铅络合配体的水环境中铅（Pb）生物有效性的具体测试案例。所研究的配体包括乙二胺四乙酸（EDTA）、内消旋 - 2,3 - 二巯基丁二酸（DMSA）、亮氨酸、蛋氨酸、半胱氨酸、谷胱甘肽和腐殖酸（HA），并且我们还使用了中国第三大湖太湖的天然水样进行实验。我们发现，根据对数 - S 形趋势，随着配体浓度的增加，EDTA、DMSA、半胱氨酸、谷胱甘肽和 HA 的添加显著降低了铅的生物有效性。太湖水中溶解有机碳的增加也有相同的效果，而亮氨酸和蛋氨酸在所测试的浓度下对生物有效性没有显著影响。我们发现生物报告器的结果与我们根据所测试的不同配体的相对络合亲和力预期的水体铅的减少情况一致。对于已知合理准确的电离和络合常数的 EDTA 和 HA，形态建模与生物报告器的响应在被美国环境保护局认可为基于形态的风险评估应用合理的不确定性水平内是一致的。这些发现代表了朝着使用生物报告器技术简化用于环境风险评估的形态建模的生物学确认或验证迈出的第一步。
