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

北美裂谷盆地横跨新泽西州部分地区(纽瓦克盆地)，发育含砷的红色、灰色和黑色页岩。新泽西州地质调查局最近的一项研究确定，该地区15-30%的水井的砷含量超过10g/L，高达215g/L。人类在环境中暴露于砷的典型途径是饮用饮用水，而饮用砷浓度超过10 mg/L的水极大地增加了个人患肺癌和膀胱癌的风险(NRC，2001)。因此，美国环保局建议将饮用水中砷的最高污染水平从50毫克/L降低到10毫克/L(美国环保局，2001年)。纽瓦克盆地的砷动员可能是由于黑色和灰色页岩中的黄铁矿被氧化，和/或从红色页岩中的赤铁矿或其他铁氧化物中释放出砷(Serfes等人，2004年)。尽管化学和物理过程在这些矿物的风化过程中发挥了作用，但也有证据表明，微生物可能对这一过程至关重要。这一建议的假设是，微生物在纽瓦克盆地及其地下水中砷的动员和形态中起着决定性的作用。将实现三个目标：1)比较与纽瓦克盆地发现的灰色/黑色页岩和红色页岩有关的附着和悬浮微生物的群落结构。据推测，受黄铁矿影响的含水层与受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)考察微生物在常温(近中性)pH条件下对天然黄铁矿和赤铁矿中砷的活化作用。提出了氧化铁剂促进黄铁矿中砷的释放，以及铁还原剂在缺氧条件下对赤铁矿中砷的活化作用。此外，砷的氧化剂和还原剂在控制As(V)和As(III)的相对丰度方面发挥了积极作用，从而影响了砷的迁移和分配。将对参与砷动员和形态形成的生物进行鉴定和表征。3)利用基于16S rDNA序列的生物分子标记，鉴定纽瓦克盆地与黄铁矿和/或赤铁矿页岩有关的铁利用微生物和参与砷形态形成的利用砷微生物。利用荧光原位杂交(FISH)和扫描电子显微镜(SEM)观察了黑色页岩和红色页岩表面铁和砷活性微生物的空间分布。生物体与页岩中的特定矿物共生，如铁氧化剂附着在黄铁矿上，亚砷酸盐氧化剂与富As(V)的铁氧化物共生。了解微生物群落在从地质介质中动员As方面的作用，将对我们了解地球环境中的生物地质风化和微量元素循环的基础知识做出新的贡献。了解导致从天然浓缩矿物中动员砷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，世界各地其他类似的沉积盆地是饮用水的来源。

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.