Chemistry of Arsenic in Soils: I. Sorption of Arsenate and Arsenite by Four Australian Soils

Abstract

Ten soils varying widely in chemistry and mineralogy were used to examine the physical and chemical properties that influence As sorption processes in soils. The sorption of As was measured using a batch technique with Asv and AsIII concentrations added in background solutions of NaNO3 (0.003–0.3 mol L−1) and a range of pH values (2.0–8.5). The soils generally sorbed more Asv than AsIII at equivalent As concentrations. In general, highly oxidic soils sorbed three times more Asv than soils containing small amounts of oxidic minerals. The effect of pH on As sorption varied considerably among the soils. In soils with low concentrations of oxidic minerals, increasing pH had little affect on the amount of Asv sorbed while in highly oxidic soils, sorption of Asv decreased with increasing pH. This decrease was attributed to two interacting factors, the increasing negative surface potential on the plane of sorption and increasing amount of negatively charged Asv species present in soil solution. In contrast to Asv, sorption of AsIII increased with increasing pH. The effect of ionic strength on As sorption varied between the As species. In general, there was a pH (∼3) below which Asv sorption decreased with increasing ionic strength and above which the reverse occurred. For AsIII species, increasing ionic strength had little effect on the amount of As sorbed.

Individual and combined phytotoxic effects of cadmium, lead and arsenic on soybean in Phaeozem

“…The investigations showed that As sorption was largely dependent on soil pH, and there was a general decrease in As (V) sorption as pH increase, while the proportion of As (III) sorbed by soil increased with increasing pH (Smith et al 1999). Smith et al (1999) observed that sorption by the soil ranged from approximately 0.80 of added As (III ) at low pH, to approximately 0.95 of added As (III) at pH 6 to 7. As stated previously, As (III) sorbed by the soil in this study was relatively higher at pH 6.76.…”

“…Arsenate [As (V) ] and arsenite [As (III) ] are the primary forms of inorganic As in soils, and As (III) is the most toxic, soluble, and mobile species found in the environment (Masscheleyn et al 1991, Smith et al 1999). The investigations showed that As sorption was largely dependent on soil pH, and there was a general decrease in As (V) sorption as pH increase, while the proportion of As (III) sorbed by soil increased with increasing pH (Smith et al 1999). Smith et al (1999) observed that sorption by the soil ranged from approximately 0.80 of added As (III ) at low pH, to approximately 0.95 of added As (III) at pH 6 to 7.…”

Arsenic present in the soil‐vine‐wine chain in vineyards situated in an old mining area in Trentino, Italy

“…In aerobic conditions, the desorption of As(V) by the soil increases along with pH as a consequence of the increased negative charges of soil colloids [3,6]. Nevertheless, a decrease in pH, for example, in the rhizosphere, may result in the dissolution of Fe and Al oxides and hydroxides, with the consequent codissolution of As bonded to this fraction [7].…”

Arsenic compounds in the leaves and roots of radish grown in three soils treated by dimethylarsinic acid

“…The effect of soil (iii) Fluvisols: The highest total extractable As contents in both seasons because of lack of sorption sites and/or low content of organic matter in this soil were observed in this case. In soils with low content of oxide minerals was observed three times lower sorption of arsenate compared to highly oxidic soils (Smith et al 1999). Almost all the arsenic present in extracts was DMA (98%) without any changes between growing seasons.…”