Arsenic Characterisation in Industrial Soils by Chemical Extractions

Abstract

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.

Assesment of Trace Elements and Mobility of Arsenic and Manganese in Lagoon Sediments of the Salars of Huasco and Coposa, Chilean Altiplano

“…Further, the authors proved that the extractable As is originated from the fraction of amorphous Fe oxides and does not depend on metal contents. On the matter of the adsorption of As on Fe oxides, it has been proved that these compounds, found in soils and sediments, have a tendency to adsorb in its surface As species inserted by anthropogenic environment activities 5,33,35,38 . In salty lagoons, and although in a very low proportion, the Fe oxide found in sediments could also be able to adsorb arsenites or arsenates from the waters that cover them.…”

“…In Scotland soils, with the use of ammonium oxalate -oxalic acid buffer to extract Se, analyzed Fe, Mn, Al and Si and reported a slight recovery of Se, but did report an efficient dissolution of Fe and Al oxides 38 . Similarly, analyzing soils contaminated with As, employed the above mentioned buffer for simple, triple and sequence-phase extraction procedures in order to determine links between As and Fe and Al oxyhydroxides 38 . Further, the authors proved that the extractable As is originated from the fraction of amorphous Fe oxides and does not depend on metal contents.…”

Operationally defined associations of arsenic and copper from soil and mine waste in south-west England

“…Samples from very polluted areas have much higher contents of trace elements and Fe. The Tessier scheme applied to these soils did not allow a correct evaluation of the Fe associated fraction and lead to the overestimation of the residual fraction, giving in consequence a far too low risk assessment (Gleyzes et al, 2001(Gleyzes et al, , 2002.…”

“…Due to the high content of Fe in the studied soils (3.6 -31.5%), the reduction step (hydroxylamine hydrochloride extraction) of the classical Tessier protocol was modified according to Shuman (1985), as proposed by Gleyzes et al (2001) and the additional two steps targeting Fe-oxides were included: extraction with the oxalate buffer (in the dark) for amorphous Feoxides solubilisation and extraction with the oxalate buffer in Ascorbic Acid (in the light) for solubilisation of crystalline Fe-oxides. This paper presents results of the As and Cu fractionation by sequential extraction on soil and waste samples from the Devon Great Consols site.…”

Untitled

“…Natural arsenic concentrations in some areas are high enough to affect human health 1 . It can be toxic to plants or may accumulate in plants and thereby enter the animal and human food chain.…”