Collaborative Research: Biogeochemical Controls on the Dynamics of Organoarsenic Transformation

合作研究：有机砷转化动力学的生物地球化学控制

• 批准号: 0719796
• 负责人: Madeline Schreiber
• 金额: $ 12.65万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0719796&HistoricalAwards=false
• 关键词: Collaborative; Research; Biogeochemical; Controls; Dynamics

Organoarsenic compounds are widespread in nature, occurring in freshwater and marine as well as terrestrial environments. Organisms, including bacteria, fungi, algae, invertebrates, vertebrates and even humans, can biotransform arsenic (As), converting inorganic to organic As, and in some cases vice-versa, producing a range of structurally simple to complex organoarsenic compounds in the environment. In addition to natural sources, organoarsenicals have been synthesized for agricultural, medicinal, and military uses. The use of organoarsenicals in the poultry industry, for example, has increased dramatically as the industry has grown. Roxarsone (3-nitro 4-hydroxybenzene arsonic acid) is added to poultry feed up to 45.5g per ton for the purpose of improving weight gain, feed efficiency, and pigmentation. When roxarsone is removed from feed for a 5-d period before slaughter, As concentrations in tissue are below the USFDA limit of 0.5 mg/kg. The majority (95%) of the As is excreted from the animal, resulting in elevated As (15 to 77 mg/kg) in poultry litter. Because poultry litter is rich in nutrients, more than 90% of it is land-applied as fertilizer. The disposal of poultry waste through land application results in release of an estimated 10^6kg of As to the environment. Recent work has demonstrated that As in poultry litter is highly water soluble and thus potentially mobile. Biotransformation of roxarsone and other organoarsenicals has been documented in the laboratory, but to date, there is little known about the ultimate fate of roxarsone, and other organoarsenicals, in watersheds. The goal of our proposed research is to examine the biogeochemical controls on organoarsenic transformation in a watershed within the Delmarva Peninsula, a region of intense poultry production. Our main hypothesis is that organoarsenic transformation is carried out by diverse microbial populations under a range of biogeochemical conditions. We will conduct intensive field monitoring of soil, ground, and surface waters before and after litter application to determine the concentration and form of As in each of these water types. We will use biochemical and molecular techniques to identify and characterize microbial communities in the water samples and to examine the impact of biogeochemical conditions on microbial community structure. To enhance public understanding of water quality, we will work with students, teacher, and community groups on water quality sampling projects on two river systems, one in a mostly forested and rural area (New River, Southwestern VA) and another impacted by agricultural and industrial land uses in an urban area (Allegheny, Monongahela, and Ohio Rivers, Pittsburgh, PA).

有机砷化合物广泛存在于自然界中，存在于淡水和海洋以及陆地环境中。 生物体，包括细菌、真菌、藻类、无脊椎动物、脊椎动物，甚至人类，可以生物转化砷，将无机砷转化为有机砷，在某些情况下，反之亦然，在环境中产生一系列结构简单到复杂的有机砷化合物。 除天然来源外，有机砷化合物还被合成用于农业、医药和军事用途。 例如，随着家禽业的发展，有机砷剂在家禽业的使用急剧增加。 Roxarsone（3-硝基4-羟基苯胂酸）被添加到家禽饲料中高达45.5g/吨，用于改善体重增加，饲料效率和色素沉着。 当洛克沙胂在屠宰前5天从饲料中去除时，组织中的As浓度低于USFDA限值0.5 mg/kg。 大部分（95%）的As从动物体内排出，导致家禽垫料中As含量升高（15至77 mg/kg）。 由于家禽粪便中含有丰富的营养成分，90%以上的粪便被用作肥料。 通过土地施用处理家禽废物导致估计10^6 kg As释放到环境中。 最近的研究表明，家禽粪便中的砷是高度水溶性的，因此可能是移动的。 洛克沙胂和其他有机砷的生物转化在实验室中已有记录，但迄今为止，对洛克沙胂和其他有机砷在流域中的最终命运知之甚少。 我们提出的研究的目标是检查在Delmarva半岛，一个地区的家禽密集生产的分水岭有机砷转化的生物地球化学控制。 我们的主要假设是，有机砷的转化是由不同的微生物种群在一系列的生态地球化学条件下进行的。 我们将进行密集的现场监测土壤，地面和地表沃茨之前和之后的凋落物应用，以确定在这些水类型的浓度和形式。 我们将使用生物化学和分子技术来鉴定和表征水样中的微生物群落，并研究生物地球化学条件对微生物群落结构的影响。 为了提高公众对水质的了解，我们将与学生，教师和社区团体合作，对两个河流系统的水质采样项目，一个是在一个主要是森林和农村地区（新河，西南弗吉尼亚州），另一个受农业和工业用地的影响，在城市地区（阿勒格尼，莫农加希拉，和俄亥俄州河流，匹兹堡，宾夕法尼亚州）。