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发展。对于汞污染的沉积物和土壤，除了封顶和疏浚之外，几乎没有可用的补救方案。就地修复尚未广泛用于汞，但在成本和保护生态系统服务方面具有显著优势，特别是在低/中度污染的大面积地区。最近的两项重大进展提高了开发有效的汞原位修复方案的机会。首先，最近的实验室和现场试验表明，原位活性炭改性剂作为薄层应用于未受干扰的沉积物或土壤，可以显着减少污染地点的甲基汞暴露。其次，今年早些时候发现的负责微生物汞甲基化的基因对（hgcAB）将首次确定环境中汞甲基化微生物的分布和活性。含有这些基因的生物似乎相对罕见，它们在自然界的分布仍然未知。这有可能显著改善甲基汞生产模型。本研究将利用这两项发展，以及其他一些新工具，更好地了解对甲基汞生产和生物利用度的控制，开发原位修复方法，并确定生物地球化学特征，使其适合这些技术。利用这些新信息，我们的目标是建立一个影响污染地区汞和甲汞生物利用度的因素的经验模型，以：1)确定使汞污染地点适合原位吸附剂修复的特征，以及2)设计降低甲汞生物利用度的吸附剂修正/薄盖层策略。主要的研究地点将是新泽西州贝里溪的一个盐沼，在那里，我们刚刚开始了使用活性炭原位吸附剂修复的现场试验。将在Berry's Creek沼泽进行更多的实地试验，以评估更大范围的黑碳的相对功效。这项在贝里溪的密集工作将辅以使用其他汞污染地点的沉积物和土壤的实验室微观研究。这种方法将用于评估各种黑碳在更广泛的生物地球化学和现场条件下的功效。

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.