Chemical Processes Affecting the Mobility of Heavy Metals and Metalloids in Soil Environments

Abstract

The mobility, bioavailability, and toxicity of metal (-loid)s are influenced by their interactions with phyllosilicates, organic matter, variable charge minerals, and microorganisms. Physicochemical processes influencing the chemistry of metal(-loid)s in soil environments include sorption/desorption, solution complexation, oxidation-reduction, and precipitationdissolution reactions. In particular, the sorption/desorption reactions of metal(loid)s on/from soil sorbents are influenced by pH, nature of soil components, and presence and concentrations of cations and inorganic anions. In recent years, many extraction tests have been used for assessing trace elements mobility and phytoavailability. Chemical speciation of toxic elements may be achieved by spectroscopic analyses (XAS), which provide information about oxidation state, symmetry, and identity of the coordinating ligand environment, and possible solid phases.

The Response of Duckweed (Lemna minor L.) Roots to Cd and Its Chemical Forms

“…to variable transport efficiencies, mobilities, and thus modes of accumulation and distribution [41,42]. For example, high metal mobility is often associated with ethanol forms (F E ), whereas metals in the form of insoluble phosphates (or those which are firmly adsorbed on the cell wall) cannot migrate freely and effectively [14].…”

87Sr/86Sr and trace element mapping of geosphere-hydrosphere-biosphere interactions: A case study in Ireland

“…Using these reagents provided a best estimate of (1) the cations available for plants via ion-exchange in the soil (NH4NO3), and (2) the cations leachable with water flowing through the soil (ultra-pure H2O). These solutions do not extract elements bound to organics (Caporale and Violante, 2016). According to Pearcy et al (2000), the particular salt solution chosen does not significantly affect the amount of ions extracted, as in any case, nearly all exchangeable cations are released into solution.…”

Formation, properties and reactivity of coprecipitates and organomineral complexes in soil environments

“…Iron or Al may precipitate alone forming many Fe-or Al-oxides of different crystallinity, mineralogy, surface properties and reactivity (Cornell and Schwertmann, 1996), but they may also coprecipitate each other, in the absence or presence of organic ligands, forming mixed Fe-Al oxides. Iron(III) and Al may also coprecipitate with other bivalent cations such as Mg, Fe(II), Zn, Cu forming mixed oxides, such as layered double oxides (LDHs) (Caporale et al, 2011;Caporale and Violante, 2016;Pigna et al, 2016).…”