Relations between Arsenic Speciation and Mobility in Mine Drainage Sediments and Microbial Communities

Mine drainage sediments concentrate toxic elements issued from minerals alteration processes. For metalloids such as arsenic or antimony, sediments are considered as a sink and also a source since according to redox, temperature and pH conditions soluble forms can be generated contributing to water pollution. Here we address the question of factors affecting arsenic speciation and mobility at the interface of mine drainage sediments. The Gabe-Gottes arsenic mine (France) drainage sediments were chosen to address this question. Arsenic solid speciation data obtained on mine drainage sediments reveal seasonal variations. Chemical, physical, climatic and biological variables coming from waters and sediments sampled between 2010 and 2012 on five stations located upstream and downstream the Gabe-Gottes arsenic mine were analysed together. Principal Component Analysis and Partial Least Square analysis show that arsenite, (which is the more mobile arsenic form) concentration in water correlates with water parameters such as nitrogen sources, phosphates, sulphates, pH, conductivity, hydrology parameters and sediment parameters such as bacterial abundance and arsenic detoxification genes (aioA, ACR3-1) abundance in sediments. Multivariate regression trees reveal that bacterial and archaeal community structures in sediments are respectively explained by sediment iron and arsenic concentrations.