Potentially toxic element fractionation in technosoils using two sequential extraction schemes

Abstract

This study reports the chemical fractionation of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated technosoils of two former smelting and mining areas using two sequential extraction schemes. The extraction schemes used in this study were the Tessier's scheme and a modified BCR scheme. The fractions were rearranged into four equivalent fractions defined as acid soluble, reducible, oxidizable, and residual to compare the results obtained from two sequential extraction schemes. Surface soils were samples from a waste landfill contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (MDN; North France) and from a settling basin contaminated with PTE such as As, Pb, and Sb located at La Petite Faye (LPF; Limoges, France). The study of the Zn, Pb, Cd, As, and Sb partitioning in the acid soluble, reducible, oxidizable, and residual fractions of the technosoils revealed that Zn, Cd, and Pb were mainly associated with the acid soluble and reducible fractions for MDN site, while As, Sb, and Pb were associated with residual fraction for LPF site. Fractionation results indicate that the percentages of Zn, Pb, Cd, As, and Sb extracted in Fe-Mn oxide bound fraction of Tessier's scheme were always higher than those extracted by modified BCR scheme. This may be attributed to the stronger Tessier's scheme conditions used to extract this fraction. In contrast the percentages of Zn, Pb, Cd, As, and Sb extracted in the organic fraction of the modified BCR scheme were always higher than those of the Tessier's scheme. The order of mobility of PTE was as follows: Cd > Zn > Pb in MDN site and As > Sb > Pb in LPF site. PTE were distributed in all soil fractions, with the most relevant enrichments in extractable and residual fractions. A significant amount of Cd, Pb, and Zn were rather mobile, which suggests that these elements can be readily available to plants and soil organisms.

Biogeochemistry of Ni and Pb in a periodically flooded arable soil: Fractionation and redox-induced (im)mobilization

“…2) is consistent with the hypothesis that Pb origin might primarily be related to release from anthropogenic activities. Many authors reported principal Pb association with Fe-Mn oxides in polluted sediments and soils (Rodríguez et al, 2009;Qasim and Motelica-Heino, 2014;Rinklebe et al, 2016b). The main Pb ore bodies consist mainly of galena (PbS), anglesite (PbSO4), and plattnerite (PbO) (Burt et al, 2003).…”

“…Many authors noted the tendency of Pb to accumulate in soil organic matter in the range of 20e30% of total Pb (Qasim and Motelica-Heino, 2014;Rinklebe and Shaheen, 2014;Shaheen et al, 2015;Nevidomskaya et al, 2016). However, the organic fraction revealed a relatively low Pb content (6.1%).…”

“…However, it is recognized that mobilization of metals and consequent risk for the environment depends usually little on their origin and/or total soil content but upon redistribution and mobilization processes between solid phases and solution and among solid-phase components (e.g. Karczewska, 1996;Han et al, 2003;Kierczak et al, 2008;Qasim and Motelica-Heino, 2014). Heavy metals in soils are considered to exist in various solid-phase fractions, which can be measured by selective sequential dissolution (Tessier et al, 1979;Rinklebe and Shaheen, 2014).…”

“…However, high mobilization of geogenic metals has been reported and explained by their high concentrations in specific solid-phase fractions in soils (Kierczak et al, 2008;Rajapaksha et al, 2012;Vithanage et al, 2014;Hseu et al, 2015). Conversely, heavy metals added to soils, after initial fast retention slowly redistribute from labile fractions into more stable forms; thus, they may approach the fractional distribution of non-contaminated soils over time (Han et al, 2003;Qasim and Motelica-Heino, 2014).…”

Effect of nitrate and ammonium fertilization on Zn, Pb, and Cd phytostabilization by Populus euramericana Dorskamp in contaminated technosol

“…These are glauconious sand with a medium granulometry; on top of them are the clay alluvial material of the nearby River Scarpe, clays, and fine sands rich in organic matter. Three soil sampling sites named (MDN1, MDN2, and MDN3) were selected for this study according to the level of PTE concentrations (Qasim and Motelica-Heino 2014) and spatial distribution of the vegetation which essentially consists of Arabidopsis halleri L. and Avena sativa L. Surface soils (0-20 cm) were sampled at each location. The main physicochemical properties of the selected soil samples are summarized in Table 1.…”