Leaching of Arsenic in Soils Amended with Crushed Arsenopyrite Rock

초록

Arsenic and its compounds which is one of the most toxic elements that can be found naturally on earth insmall concentrations are used in the production of pesticides, herbicides, and insecticides. Most arsenic thatcannot be mobilized easily when it is immobile is also found in conjunction with sulfur in minerals such asarsenopyrite (AsFeS), realgar, orpiment and enargite. In this investigation we observed the leaching of arsenicin soils amended with several levels of gravel size of arsenopyrite collected from a road construction site. Soiland gravel size of arsenopyrite were characterized by chemical and mineralogical analyses. Results of XRFanalysis of arsenopyrite indicated that the proportion of arsenate was 0.075% (wt wt-1) while the maximumamount of arsenic in soil samples was 251.3 mg kg-1. Cumulative amounts of effluent collected from thebottom of the soil column for different mixing rate of the gravel were gradually increased where proportion ofthe gravel mixed was greater than 70% whereas the effluent was stabilized to the maximum afterapproximately 45 pore volumes of effluent or greater were collected. The arsenic in the effluent was recoveredfrom the soil columns in which the proportion of arsenopyrite gravel was 60% or greater. The total amount ofarsenic recovered as effluent was increased with increasing proportion of gravel in a soil, indicating that thearsenic in the effluent was closely related with gravel fraction of arsenopyrite.

키워드