Factors Controlling the Migration of Tailings-Derived Arsenic: A Case Study at the Yara Siilinjärvi Site

详细信息    查看全文

• 作者：Kaisa Turunen ; Soile Backnäs ; Raisa Neitola&#8230
• 关键词：Arsenic fractionation ; Arsenic mobility ; Soil chemistry ; Water chemistry ; Risk assessment
• 刊名：Mine Water and the Environment
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：35
• 期：4
• 页码：407-420
• 全文大小：1793KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geology; Water Quality/Water Pollution; Hydrogeology; Mineral Resources; Ecotoxicology; Industrial Pollution Prevention;
• 出版者：Springer Berlin Heidelberg
• ISSN：1616-1068
• 卷排序：35

文摘

The behaviour of arsenic (As) derived from tailings was investigated at the Yara Siilinjärvi apatite mine and industrial site in eastern Finland. The study assessed factors influencing the migration and fate of As and compared the anthropogenic As load to the natural geogenic background. Environmental risks related to As were assessed by examining the As concentrations in humus, glacial till, aquatic sediments, groundwater, and surface water. The occurrence and fractionation of As and the presence of secondary precipitates and geochemical transformations in the tailings and in the ambient soil and sediment were evaluated by selective extraction. The water-derived emissions were evaluated by field measurements, hydrogeochemical analysis, and modelling. Results indicate elevated environmental risks due to dust and seepage emissions from the tailings since the concentrations and mobility of As and other potentially harmful elements (PHEs) such as Co, Ni, and Zn were elevated relative to the geogenic background. These elements were mainly associated with Fe (oxy)hydroxides in the soil and their mobility was closely linked to Fe biogeochemistry. Additionally, although the concentrations of As and PHEs were high in the tailings pond and seepage water, they decreased in ambient groundwater and surface water, indicating Fe (oxy)hydroxide stability. This was supported by hydrogeochemical modelling, which indicated precipitation of Fe oxides and hydroxides. According to speciation modelling, As was present mainly as toxic trivalent arsenious acid (H₃AsO₃) in groundwater and as the less toxic pentavalent As acid (H₂AsO₄−p> and HAsO₄2−p>) in surface water.