Influence of limestone drains and seasonality on arsenic speciation in a stream surrounding a gold mineralization area

摘要

Arsenic is a trace element that often occurs in gold mineralization areas associated with sulfide minerals. Acid Mining Drainage (AMD) caused by sulfide and ferrous iron oxidation, as well as biomethylation are important processes related to As mobility and toxicity in mining areas. This work focuses on the influence of limestone drains on As mobility and speciation in a stream surrounding a gold mineralization area. Total arsenic contents and speciation were mainly influenced by the proximity to the mineralized area, but limestone drains efficiently decreased soluble As. Arsenate (As~V) was the dominant species downstream the limestone drain. For organic arsenicals, only DMA was detected close to the mineralization area, upstream the limestone drain, which was related to the presence of algal mats and gel flocs.