Chromium fractionation in semi-arid soils amended with chromium and tannery sludge

Distribution and mobility of Cr in tannery waste amended semi-arid soils under simulated rainfall

“…The distribution of Cr fractions observed in this study were different from those reported by Barajas-Aceves et al [36], who used the same soils to evaluate the effects of treatment with a tannery sludge that contained a lower amount of Cr, nitrogen and carbon than the sludge evaluated here [36]. Specifically, they reported that after 120 days of incubation, the residual fraction of Cr had increased gradually with time.…”

“…The results of the present study and the study conducted by Barajas-Aceves et al [36] suggest that the tannery sludge characteristics are so important that they define the Cr fractionation in the soil [37]. Furthermore, these findings indicate that the incubation system used may influence the microbial processes in the soil and that the presence of organic compounds plays an important role in determining which fraction of Cr dominates [38,39].…”

Fractionation and availability of heavy metals in tannery sludge-amended soil and toxicity assessment on the fully–grownPhaseolus vulgariscultivars

“…The latter fraction meaning a lower degree of mobility, [3] since Fe hydrous oxides have been shown to be the most important compounds in the sorption of trace metallic pollutants. [2] Oxidation of Cr 3+ to Cr 6+ by Mn oxides is a significant environmental hazard because it represents the transformation of a relatively nontoxic species into a toxic species. [3] Nonetheless, it should be noted that in the present study only 6 mg Cr 6+ kg −1 were detected in tannery sludge, assuming that the Cr in the tannery sludge amended soil was Cr 3+ because Cr 6+ was no longer detected.…”

“…Cr 6+ is much more reactive, toxic and shows a higher mobility in soil than Cr 3+ . [2,3] Hence, determination of the total heavy metal content of soil samples is not sufficient to evaluate its mobility and, consequently the bioavailability of toxic metals to living organisms. [4] The application of sequential extraction procedures allows determination of the chemical forms in which the elements appear to be associated in soils.…”

An approach for arsenic in a contaminated soil: Speciation, fractionation, extraction and effluent decontamination

“…In addition, sequential extractions are carried out with reagents of different chemical properties, in order to identify fractions of elements with different labilities. Several sequential extractions schemes for metals (Tessier et al, 1979;Meguellati et al, 1983;Quevauviller et al, 1994) have been developed; in particular Tessier's scheme (Tessier et al, 1979) is one of the most widely used and it has been extensively applied to aquatic sediments (Pagnanelli et al, 2004), soils (Karathanasis and Pils, 2005) and sludges (Barajas-Aceves et al, 2007).…”