Mestrot Adrien, Uroic M Kalle, Plantevin Thomas, Islam Md Rafiqul, Krupp Eva M, Feldmann Jörg, Meharg Andrew A
Institute for Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, Scotland, U.K.
Environ Sci Technol. 2009 Nov 1;43(21):8270-5. doi: 10.1021/es9018755.
Arsenic volatilization in the environment is thought to be an important pathway for transfer from terrestrial pools to the atmosphere. However, this phenomenon is not well characterized due to inherent sampling issues in trapping, quantifying and qualifying these arsine gases; including arsine (AsH(3)), monomethyl arsine (MeAsH(2)), dimethyl arsine (Me(2)AsH) and trimethyl arsine (TMAs). To quantify and qualify arsines in air we developed a novel technique based on silver nitrate impregnated silica gel filled tubes. The method was characterized by measuring the recovery of trapped arsines after elution of this chemo-trap with hot boiling diluted nitric acid. Results from three separate experiments, measured by ICP-MS, showed that the method is reproducible and quantitative. Arsine species recovery ranged from 80.1 to 95.6%, with limit of detection as low as 3.8 ng per chemo-trap tube. Moreover, HPLC-ICP-MS analysis of hot boiling water eluted traps showed that the corresponding oxy ions of the arsines were formed with the As-C bonds of the molecule intact, hence, allowing qualification of trapped arsine species. A microcosm study examining volatile arsenic evolution from field contaminated Bangladeshi paddy soils (24.2 mg/kg arsenic) was used to show the application of silver nitrate chemo-trapping approach. Traps were placed on the inlet and the outlet of microcosms containing the soils that were either (cattle derived) manured or not, or flooded or not, in a factorial design. The headspace was purged with air at a flow rate of 12 mL/min. Results showed that as much as 320 ng of arsenic (0.014% of total soil content) could be emitted in a 3 week period for manured and flooded soils and that TMAs was the dominant species evolved, with lesser quantities of Me(2)AsH. No volatile arsenic evolution was observed for nonmanured treatments, and arsine release from the nonflooded, manured treatment was much less than the flooded treatment.
环境中的砷挥发被认为是从陆地库转移到大气的重要途径。然而，由于在捕获、量化和鉴定这些胂气（包括胂（AsH₃）、一甲基胂（MeAsH₂）、二甲基胂（Me₂AsH）和三甲基胂（TMAs））时存在固有的采样问题，这种现象尚未得到充分表征。为了量化和鉴定空气中的胂，我们开发了一种基于填充硝酸银浸渍硅胶管的新技术。该方法通过用热沸腾的稀硝酸洗脱这种化学捕集器后测量捕获的胂的回收率来表征。通过电感耦合等离子体质谱（ICP-MS）测量的三个独立实验结果表明，该方法具有可重复性和定量性。胂物种的回收率在80.1%至95.6%之间，检测限低至每个化学捕集管3.8纳克。此外，对热沸水洗脱捕集器的高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）分析表明，胂的相应含氧离子在分子的As-C键完整的情况下形成，因此，能够鉴定捕获的胂物种。一项微观研究考察了受污染的孟加拉稻田土壤（砷含量为24.2毫克/千克）中挥发性砷的释放情况，以展示硝酸银化学捕集方法的应用。捕集器放置在含有土壤的微观模型的入口和出口处，土壤采用析因设计，分为施肥（牛粪来源）或不施肥、淹水或不淹水的情况。顶空以12毫升/分钟的流速用空气吹扫。结果表明，施肥且淹水的土壤在3周内可释放多达320纳克的砷（占土壤总含量的0.014%），且三甲基胂是释放的主要物种，二甲基胂的量较少。未施肥处理未观察到挥发性砷释放，未淹水的施肥处理的胂释放量远低于淹水处理。
