DEVELOPMENT OF IN-SITU MERCURY REMEDIATION APPROACHES BASED ON METHYLMERCURY BIOA

描述(由申请人提供)：拟议研究的目标是促进汞原位修复工具的开发。除了封顶和疏浚，汞污染的沉积物和土壤几乎没有可用的修复方案。原位修复尚未被广泛用于汞，但在成本和保护生态系统服务方面具有显著优势，特别是在污染水平较低/中等的大片地区。最近的两项重大进展增加了开发有效的汞就地修复选择的机会。首先，最近的实验室和现场试验表明，原位活化的Caron改良剂作为薄层应用于未受干扰的沉积物或土壤，可以显著减少受污染场地的甲基汞暴露。其次，今年早些时候确定了导致微生物汞甲基化的基因对(HgcAB)，这将首次确定环境中汞甲基化微生物的分布和活动。含有这些基因的生物体似乎相对罕见，它们在自然界中的分布尚不清楚。这有可能显著改进甲基汞的生产模式。这项研究研究将利用这两项发展以及其他几种新工具，以更好地了解对甲基汞生产和生物有效性的控制，开发就地修复方法，并确定可能使地点适合这些技术的生物地球化学特征。利用这些新信息，我们的目标是开发一个影响汞和甲基汞生物有效性的因素的经验模型，以：1)确定使汞污染场地适合于就地吸附剂修复的特征，以及2)设计降低甲基汞生物有效性的吸附剂修正/薄封顶策略。主要的研究地点将是新泽西州贝里克里克的一个盐沼，我们刚刚在那里开始了使用活性碳进行就地吸附修复的现场试验。还将在贝里溪沼泽进行更多的实地试验，以评估更广泛的黑碳的相对有效性。在Berry‘s Creek的这项密集工作将得到实验室微观世界研究的补充，这些研究使用了来自其他汞污染地点的沉积物和土壤。这种方法将被用来评估各种黑碳在更广泛的生物地球化学和场地条件下的有效性。

DESCRIPTION (provided by applicant): The goal of the proposed study is to advance the development of in situ remediation tools for mercury. There are few available remediation options for Hg contaminated sediments and soils, short of capping and dredging. In situ remediation has not been widely used for mercury, but offers significant advantages in cost and in preservation of ecosystem services especially for large areas with low/moderate levels of contamination. Two recent major advances improve the chances for development of effective in situ remediation options for Hg. First, recent lab and field trials show that in situ activated caron amendments, applied as a thin layer to undisturbed sediments or soils, can significantly reduce MeHg exposure from contaminated sites. Second, the identification of the gene pair responsible for microbial Hg methylation earlier this year (hgcAB) will allow the distribution and activity of Hg- methylating microorganisms in the environment to be established for the first time. Organisms that contain these genes appear to be relatively rare, and their distribution in nature remains unknown. This has the potential to significantly improve models of MeHg production. This research study will take advantage of both of these developments, and several other novel tools, to develop a better understanding of the controls on MeHg production and bioavailability, to develop in situ remediation approaches, and to identify biogeochemical characteristics that may make sites appropriate for these technologies. Using this new information, our goal is to develop an empirical model of the factors influencing Hg and MeHg bioavailability in contaminated areas to: 1) identify characteristics that make Hg- contaminated sites suitable for in situ sorbent remediation, and 2) design sorbent amendment/thin capping strategies that reduce MeHg bioavailability. The main study site will be a salt marsh in Berry's Creek, NJ, where we have just begun a field trial of in situ sorbent remediation using activated carbon. Additional field trials in the Berry's Creek marsh will be done to evaluate the relative efficacy o a wider range of black carbons. This intensive work in Berry's Creek will be supplemented with laboratory microcosm studies using sediments and soils from other Hg-contaminated sites. This approach will be used to evaluate the efficacy of a variety of black carbons across a wider range of biogeochemical and site conditions.