Microbial Controls on the Mobilization and Speciation of Arsenic from Newark Basin Shale

微生物对纽瓦克盆地页岩中砷的运移和形态的控制北美裂谷盆地横跨美国新泽西州（纽瓦克盆地）的一部分，含砷的页岩有红色、灰色和黑色。新泽西州地质调查局（NJ Geological Survey）最近进行的一项研究发现，该地区15-30%的水井砷含量超过10克/升，最高可达215克/升。人类在环境中接触砷通常是通过饮用水，饮用砷浓度超过10毫克/升的水会大大增加个人患肺癌和膀胱癌的风险（美国癌症研究委员会，2001年）。因此，美国环境保护署（EPA）建议将饮用水中砷的最大污染物水平（MCL）从50毫克/升降低到10毫克/升（USEPA， 2001年）。纽瓦克盆地的砷迁移可能是由于黑色和灰色页岩中的黄铁矿氧化，和/或赤铁矿或红色页岩中的其他氧化铁释放砷（Serfes et al, 2004）。虽然化学和物理过程在这些矿物的风化中起作用，但也有证据表明，微生物可能对这一过程至关重要。该提议的假设是，微生物在纽瓦克盆地及其地下水中砷的动员和形成中起着决定性作用。研究将有三个目标：1)比较纽瓦克盆地灰色/黑色页岩和红色页岩中附着和悬浮微生物的群落结构。假设黄铁矿影响的含水层与赤铁矿影响的含水层具有不同的微生物群落结构。这些差异将帮助我们确定对砷动员至关重要的特定生物体。2)研究微生物在环境（环中性）pH下从天然黄铁矿和赤铁矿中促进砷动员的程度。提出铁氧化剂促进黄铁矿中砷的释放，铁还原剂可能在缺氧条件下调动赤铁矿中的砷。此外，砷氧化还原剂和砷氧化还原剂在控制As(V)和As（III）的相对丰度，从而影响砷的运输和分布方面具有活性。参与砷动员和物种形成的生物将被识别和表征。3)利用基于16S rDNA序列的生物分子标记技术，鉴定与纽瓦克盆地黄铁矿和/或赤铁矿页岩相关的铁利用微生物，以及与砷形成相关的砷利用微生物。利用荧光原位杂交技术（FISH）和扫描电镜技术（SEM）观察了黑色和红色页岩表面铁和砷活性微生物的空间分布。这些有机物可能与页岩中的特定矿物相结合，例如，铁氧化剂与黄铁矿相结合，亚砷酸盐氧化剂与富As(V)的氧化铁相结合。了解微生物群落在从地质介质中动员砷的作用将为我们对地球环境中生物地质风化和微量元素循环的基础知识作出新的贡献。了解导致砷从天然富集的矿物质中迁移的过程，对于预测和保护饮用水供应的质量至关重要。虽然该项目针对的是新泽西州纽瓦克盆地的砷问题，但北美东部裂谷盆地是美国大西洋中部和东北部地区的主要地层，世界上其他类似的沉积盆地也是饮用水的来源。

ABSTRACT OF RESEARCHMICROBIAL CONTROLS ON THE MOBILIZATION AND SPECIATION OF ARSENIC FROM NEWARK BASIN SHALEThe North American Rift Basin spans part of New Jersey (Newark Basin) and has arsenic containing red, gray and black shale. In a recent study conducted by the NJ Geological Survey, it was determined that 15-30% of the wells from this area had arsenic levels exceeding 10 g/L and up to 215g/L. Human exposure to arsenic within the environment is typically through drinking water and the consumption of water with arsenic concentrations greater than 10 mg/L greatly increases an individual's risk of developing lung and bladder cancer (NRC, 2001). As a result, the U.S. Environmental Protection Agency (EPA) has proposed a reduction in the maximum contaminant level (MCL) for arsenic in drinking water from 50 mg/L to 10 mg/L (USEPA, 2001). Arsenic mobilization in the Newark Basin could be due to the oxidation of pyrite in black and gray shale, and/or release of arsenic from hematite or other iron oxides in red shale (Serfes et al, 2004). Although chemical and physical processes play a role in the weathering of these minerals, there is also evidence that microorganisms may be essential to the process. The hypothesis of this proposal is that microorganisms play a defining role in the mobilization and speciation of arsenic in the Newark Basin and its groundwater. Three objectives will be undertaken: 1) To compare the community structure of attached and suspended microorganisms associated with gray/black shale and with red shale found in the Newark Basin. It is hypothesized that pyrite-impacted aquifers will have a different microbial community structure than those impacted by hematite. These differences will help us identify the specific organisms critical to arsenic mobilization. 2) To examine the degree to which microbes enhance arsenic mobilization at ambient (circumneutral) pH from native pyrite and hematite. It is proposed that iron oxidizers facilitate the release of arsenic from pyrite and that iron reducers may mobilize arsenic from hematite under anoxic conditions. In addition, it is proposed that arsenic oxidizers and reducers are active in controlling the relative abundance of As(V) and As(III) and thereby affecting arsenic transport and distribution. The organisms involved in arsenic mobilization and speciation will be identified and characterized. 3) To identify iron-utilizing microbes associated with the pyrite and/or hematite shale and arsenic-utilizing microbes involved in the speciation of arsenic from the Newark Basin using biomolecular markers based on 16S rDNA sequence. Fluorescent in-situ hybridization (FISH) and scanning electron microscopy (SEM) will be used to observe the spatial distribution of both iron and arsenic active microbes on surfaces of black and red shale. It is proposed that the organisms will associate with specific minerals in the shale, for example, iron oxidizers will attach to pyrite and arsenite oxidizers will be associated with As(V)-enriched iron oxides. Understanding the role that the microbial community plays in mobilizing As from the geologic media will constitute a new contribution to our basic knowledge of biogeological weathering and trace element cycling in the earth's environment. Understanding the processes that lead to the mobilization of arsenic from naturally-enriched minerals is essential to predicting and protecting the quality of drinking water supplies. Although this project is directed at the arsenic issue in the Newark Basin in New Jersey, the Eastern Rift Basin of North America is a major formation in the mid-Atlantic and northeast region of the US and other similar sedimentary basins around the world are sources of drinking water.