A critical assessment on arsenic partitioning in mine-affected soils by using two sequential extraction protocols

ABSTRACT

The highly degraded mine-affected soils of Lavrion, central Greece, are greatly polluted by heavy metals and arsenic (As). To assess As partitioning in the soils of the area, Wenzel and BCR (Community Bureau of Reference) sequential extraction procedures (SEP) were applied to 29 top soils. The results of the Wenzel SEP showed that As was mainly bound to the well-crystallized (33.3%) and to the amorphous/poorly-crystalline (30.1%) oxides of Fe, Al, and Mn. According to the BCR scheme, most of the total As (78.4%) was retained in the residual phase. Low mobility factor values (Wenzel: 0.34%; BCR: 1.56%) clearly demonstrate the low availability and mobility of As in the studied soils. The specifically-sorbed/inner-sphere and the reducible fractions of As, obtained by the Wenzel SEP, were positively correlated with clay and Fe oxides content, respectively. The reducible As fractions of both SEPs were negatively correlated with carbonates content indicating that carbonates may partially control As sorption on Fe oxides. The comparative evaluation of the two SEPs showed that the application of the BCR protocol in contaminated soils cannot provide reliable information on As sequestration in soils but it can be a first estimate of As labile forms.

KEYWORDS:

• Wenzel fractionation scheme
• BCR sequential extraction protocol
• arsenic
• mining
• soil

Disclosure statement

No potential conflict of interest was reported by the authors.