Arsenic behavior in mining soil

A methodology based on leaching tests in conjunction with mineralogy analysis was used to investigate the mobility of arsenic from a mining soil. The specific objectives of the research presented here were to examine the effect of. (i) soil components (e.g., mainly iron content) on arsenic fixation, (ii) aging in different environmental conditions on arsenic speciation and liquid-solid partitioning, and (iii) pH and redox changes on arsenic mobilization. Results indicated that arsenic release at the natural pH of the soil (i.e., during contact with dionized water) is limited by the very low solubility of arsenic in the interstitial solution of the soil and by the stability of the arsenic complexes formed with the amorphous solid phases of the soil (mainly ferric hydroxides). However, a potential mobilization hazard exists over the long term under specific leaching conditions (i.e., pH or redox gradient, and chelation effect) which can arise in a given management scenario of a contaminated site.