AECOM, Conshohocken, Pennsylvania, USA.
EHS Support, Collegeville, Pennsylvania, USA.
Integr Environ Assess Manag. 2019 May;15(3):374-384. doi: 10.1002/ieam.4133. Epub 2019 Apr 4.
This study evaluated potential effects of mercury (Hg) on benthic macroinvertebrates in the South River, Virginia, USA. The study used a multiple lines of evidence approach, including spatially and temporally matched sediment chemistry, biological, and toxicological information (Sediment Quality Triad), exposure and effect analysis in bulk and interstitial sediment and interstitial water, and critical body residue analysis. Ten-day Chironomus dilutus and Hyalella azteca toxicity tests established site-specific no-effect concentrations (NOEC) at 18.9 μg/g total Hg (THg) and 102 ng/g methylmercury (MeHg). However, the benthic community at these locations was impaired, with lower mayfly and caddisfly composition. Few locations had concentrations of THg and MeHg that exceeded the NOEC in bulk or interstitial sediment. The THg concentrations in interstitial water were far below concentrations expected to reduce survival in benthic invertebrates, and only a low percentage of samples exceeded sublethal (growth) low-effect concentrations (LOEC) for THg or MeHg. The THg concentrations in invertebrate tissue did not exceed the NOEC or LOEC in the South River, and MeHg concentrations exceeded the LOEC at all locations, including those with no evidence of benthic impairment, illustrating the uncertainty associated with this line of evidence. Finally, statistical modeling that evaluated diversity of sensitive invertebrate species as a function of Hg exposure, geomorphological parameters, and physicochemical variables indicated that physicochemical and geomorphological parameters were most predictive of benthic community; where Hg was indicated, we were unable to distinguish between models with or without interstitial water Hg. Overall, the lines of evidence indicate that Hg, while clearly toxic to invertebrates at sufficiently high exposure concentrations, is not negatively impacting invertebrate communities in the South River. This study illustrates the difficulty of assessing risks to invertebrates using traditional tools of risk assessment and identifies critical gaps in knowledge that complicate the management of Hg risk. Integr Environ Assess Manag 2019;00:000-000. © 2019 SETAC.
本研究评估了汞（Hg）对美国弗吉尼亚州南河底栖大型无脊椎动物的潜在影响。该研究采用了多种证据方法，包括时空匹配的沉积物化学、生物和毒理学信息（沉积物质量三联体）、在整体和间隙沉积物和间隙水中进行的暴露和效应分析，以及临界身体残留分析。为期 10 天的摇蚊和食蚊鱼毒性测试确定了特定地点的无效应浓度（NOEC）为 18.9μg/g 总汞（THg）和 102ng/g 甲基汞（MeHg）。然而，这些地点的底栖群落受到了损害，蜉蝣和石蚕的组成较低。在整体或间隙沉积物中，很少有地点的 THg 和 MeHg 浓度超过 NOEC。间隙水中的 THg 浓度远低于预期会降低底栖无脊椎动物存活率的浓度，只有一小部分样品超过了 THg 或 MeHg 的亚致死（生长）低效应浓度（LOEC）。南河无脊椎动物组织中的 THg 浓度未超过 NOEC 或 LOEC，而所有地点的 MeHg 浓度均超过 LOEC，包括那些没有底栖受损迹象的地点，这说明了该证据线所存在的不确定性。最后，评估敏感无脊椎动物物种多样性作为 Hg 暴露、地貌参数和物理化学变量函数的统计模型表明，物理化学和地貌参数是底栖群落最具预测性的因素；在表明 Hg 存在的情况下，我们无法区分是否存在间隙水 Hg 的模型。总体而言，这些证据表明，尽管 Hg 在足够高的暴露浓度下对无脊椎动物具有明显的毒性，但它并没有对南河的无脊椎动物群落产生负面影响。本研究说明了使用传统风险评估工具评估无脊椎动物风险的困难，并确定了使 Hg 风险管理复杂化的知识关键差距。《综合环境评估与管理》2019 年；000-000. © 2019 SETAC.
