Adsorption of arsenate on soils. Part 2: Modeling the relationship between adsorption capacity and soil physiochemical properties using 16 Chinese soils

Abstract

Citrate-dithionite extractable Fe has the most important positive influence on arsenate adsorption on soils. AbstractAn attempt has been made to elucidate the effects of soil properties on arsenate adsorption by modeling the relationships between adsorption capacity and the properties of 16 Chinese soils. The model produced was validated against three Australian and three American soils. The results showed that nearly 93.8% of the variability in arsenate adsorption on the low-energy surface could be described by citrate-dithionite extractable Fe (Fe CD ), clay content, organic matter content (OM) and dissolved organic carbon (DOC); nearly 87.6% of the variability in arsenate adsorption on the high-energy surface could be described by Fe CD , DOC and total arsenic in soils. Fe CD exhibited the most important positive influence on arsenate adsorption. Oxalate extractable Al (Al OX ), citratedithionite extractable Al (Al CD ), extractable P and soil pH appeared relatively unimportant for adsorption of arsenate by soils.

Effects of Oxalate and Humic Acid on Arsenate Sorption by and Desorption from a Chinese Red Soil

“…The equation showed significant correlation with R values ranging from 0.996 to 0.998 (p < 0.01). The As(V) sorption generally increased with increasing initial As(V) concentrations from 0 to 2.0 mM, and the soil showed a rather higher sorption capacity for As(V) compared with the reported data for As(V) sorption on soils (Livesey and Huang, 1981;Jiang et al, 2005). The XRD analysis indicated only minor amounts of iron oxides in the soil.…”

“…However, the ratios of oxalate to citrate-dithionate extractable Al and Fe (0.30 for Al and 0.14 for Fe) suggested that significant proportions of Al and Fe were in forms of low crystallinity (Johnson et al, 1986). This accounted for the high sorption capacity of the soil (Livesey and Huang, 1981;Jiang et al, 2005). With the increasing As(V) sorption, significant enhancements in the release of dissolved organic carbon (DOC) and the major inorganic anions, such as OH − and PO 4 3− , were observed (Table 3).…”

“…Therefore, the use of a whole soil to examine sorption mechanisms is necessary (Smith et al, 2002;Violante and Pigna, 2002;Jiang et al, 2005). The Chinese red soil, a main soil type in south China, shows a rather high sorption capacity for As(V) (Jiang et al, 2005). Research on the sorption and desorption of As(V) in the soil is therefore of particular necessity.…”

“…Arsenate sorption on soil can not be explained completely by any of the mechanisms proposed for individual soil components. Therefore, the use of a whole soil to examine sorption mechanisms is necessary (Smith et al, 2002;Violante and Pigna, 2002;Jiang et al, 2005). The Chinese red soil, a main soil type in south China, shows a rather high sorption capacity for As(V) (Jiang et al, 2005).…”

Phosphate has a differential influence on arsenate adsorption by soils with different properties

“…The As (V) adsorption on ACpa occurred predominantly on the low-energy surface. Soil properties strongly affect As adsorption and subsequently influence the environmental fate of As (Jiang et al 2005b, Buschmann et al 2006, Girouard and Zagury 2009. Jiang et al (2005a) suggested that the Langmuir two-surface equation describes As (V) adsorption better than the Langmuir one-surface equation for soils with lower contents of OM, DOC, or extractable P, where both high-energy and low-energy surface adsorption sites would be available.…”