Arsenic Characterisation in Industrial Soils by Chemical Extractions

The purpose of this research was to find a reliable and easy to use method to characterise As in iron-rich industrial or mining site soils. In this objective classical sequential extraction schemes and single extractions with EDTA and phosphate solutions were used. Results showed that classical Tessier's scheme overestimated residual As. A scheme specific to anionic species was also not really suitable to evaluate As distribution in these iron-rich soils. A more complex scheme using specific iron reagents indicated a correlation between iron dissolution and arsenic leaching and these results were confirmed by single extractions with EDTA and oxalate solutions. Finally a simplified and less time consuming scheme was established, tested on diverse industrial soils and validated on a certified sediment reference material. It allowed evaluation in 24 hours of the easily extractable fraction, amount solubilized under reducing conditions and As strongly bound to the soil.