Effect of natural organic matter on arsenic release from soils and sediments into groundwater

Abstract

Arsenic (As) contamination in groundwater has received significant attention recently. Natural and anthropogenic sources contribute to the worldwide occurrence of As contamination. As speciation is an important factor related to its toxic and mobile behavior. The release of As from soils and sediments into groundwater is governed by several geophysicochemical processes, of which, As sorption behavior is of principle significance. This review paper summarizes existing information regarding the effects of natural organic matter (NOM) on the fate and mobility of As species in the environment. NOM may enhance the release of As from soils and sediments into the soil solution, thereby facilitating As leaching into the groundwater. The main influencing mechanisms include competition for available adsorption sites, formation of aqueous complexes, and/or changes in the redox potential of site surfaces and As redox speciation. NOM may also serve as binding agents, thereby reducing As mobility. However, comparably little research has been performed on this aspect. Since most investigations have been done on purified minerals under laboratory conditions, further research involving various geological materials under natural environmental conditions is required. Development of proper geochemical conceptual models may provide means of predicting the role of NOM in arsenic leaching and/or immobilization.

The impacts of different long-term fertilization regimes on the bioavailability of arsenic in soil: integrating chemical approach with Escherichia coli arsRp::luc-based biosensor

“…pH and P were important direct factors governing the mobility of As in soil. It has been reported that sequestration of As from of Fe-Mn oxides of mineral surfaces was consistently increasing with lower pH (Signes-Pastor et al 2007;Wang and Mulligan 2006;Yang et al 2002), because low pH values could lead to the formation of more positively charged Fe oxides, and then positively charged Fe oxides could adsorb more As anions on the mineral surface (Lafferty and Loeppert 2005;Jain et al 1999). In this research, NPK + M and M treatments have led to a slight increase of pH, but other treatments were opposite.…”

“…7 Comparison of BCR-SEPs-determined As (F1, F2) with the biosensor-determined As at the three As addition levels: 0 mg/kg, 50 mg/kg, and 100 mg/kg Jackson et al 2006;Mladenov et al 2010). Although there is no direct conclusion to prove that As bound with organic carbon is available by biosensor cell, however, interactions between organic carbon and As can be influenced by various factors such as pH, redox potential, and other competing ions in aquatic environments, and it could cause the secondary release of As to aquatic environments and the rise of bioavailable As (Wang and Mulligan 2006). pH and P were important direct factors governing the mobility of As in soil.…”

“…Meanwhile, the release of metal including As from the solid phase of soil was influenced by organic carbon based on the formation of soluble metal-organic complexes (Cao et al 2003;Grafe et al 2002;Harvey et al 2002;Jackson et al 2006;Mladenov et al 2010;Wang and Mulligan 2006). pH and P also have been confirmed as major factors impacting the release of As by the mechanism of competitive anion exchange (De Brouwere et al 2004;Grafe et al 2002;Signes-Pastor et al 2007;Wang and Mulligan 2006;Yang et al 2002;Zhao and Stanforth 2001).…”

“…However, the application of long-term fertilization increased organic carbon concentration (Liu et al 2013;Yang et al 2011) and the content of phosphorus (P) (Ge et al 2008;Zheng et al 2008a) and changed the acidity of soil depending on the soil conditions (Dong et al 2012;Zheng et al 2008b). Meanwhile, the release of metal including As from the solid phase of soil was influenced by organic carbon based on the formation of soluble metal-organic complexes (Cao et al 2003;Grafe et al 2002;Harvey et al 2002;Jackson et al 2006;Mladenov et al 2010;Wang and Mulligan 2006). pH and P also have been confirmed as major factors impacting the release of As by the mechanism of competitive anion exchange (De Brouwere et al 2004;Grafe et al 2002;Signes-Pastor et al 2007;Wang and Mulligan 2006;Yang et al 2002;Zhao and Stanforth 2001).…”

Selenium mobilization in soils due to volcanic derived acid rain: An example from Mt Etna volcano, Sicily

“…Several mechanisms might be responsible for the decreased Se mobility under acidic conditions in SOM-rich samples. Firstly, there is less mineral dissolution occurring due to the stabilization by SOM (Wang and Mulligan, 2006) as confirmed by lower Al and Fe leachate concentrations (Table A1). Secondly, new adsorption sites can be formed on humic acid or metal-humus complexes (Kamei-Ishikawa et al, 2007).…”