title: Phosphorus-arsenic interactions in variable-charge soils in relation to arsenic mobility and bioavailability.
abstract: Phosphorus (P) influences arsenic (As) mobility and bioavailability which depends on the charge components of soil. The objective of this study was to examine P-As interaction in variable-charge allophanic soils in relation to P-induced As mobilization and bioavailability. In this work, the effect of P on arsenate [As(V)] adsorption and desorption was examined using a number of allophanic and non-allophanic soils which vary in their anion adsorption capacity. The effect of P on As uptake by Indian mustard (Brassica juncea L.) plants was examined using a solution culture, and a soil plant growth experiment involving two As-spiked allophanic and non-allophanic soils which vary in their anion adsorption capacity, and a field As-contaminated sheep dip soil. Arsenate adsorption increased with an increase in the anion adsorption capacity of soils. The addition of P resulted in an increase in As desorption, and the effect was more pronounced in the case of allophanic soil. In the case of both As-spiked soils and field contaminated sheep-dip soil, application of P increased the desorption of As, thereby increasing its bioavailability. The effect of P on As uptake was more pronounced in the high anion adsorbing allophanic than low adsorbing non-allophanic soil. In the case of solution culture, As phytoavailability decreased with increasing concentration of P which is attributed to the competition of P for As uptake by roots. While increasing P concentration in solution decreased the uptake of As, it facilitated the translocation of As from root to shoot. The net effect of P on As phytoavailability in soils depends on the extent of P-induced As mobilization in soils and P-induced competition for As uptake by roots. The P-induced mobilization of As could be employed in the phytoremediation of As-contaminated sites. However, care must be taken to minimize the leaching of As mobilized through the P-induced desorption, thereby resulting in groundwater and off site contamination.
authors: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA, Australia; CRC for Contamination Assessment and Remediation in the Environment, University of South Australia, Mawson Lakes, SA, Australia. Electronic address: Nanthi.Bolan@unisa.edu.au.
authors: Nanthi
authors: N
authors: Bolan
authors: Santiago
authors: S
authors: Mahimairaja
authors: Anitha
authors: A
authors: Kunhikrishnan
authors: Girish
authors: G
authors: Choppala
mesh_terms: D001149:Arsenates / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics; D001151:Arsenic / Q000032:analysis / Q000737:chemistry* / Q000493:pharmacokinetics; D001682:Biological Availability; D001937:Brassica / Q000737:chemistry / Q000378:metabolism; D018525:Germination / Q000187:drug effects; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry* / Q000493:pharmacokinetics; D018517:Plant Roots / Q000737:chemistry; D018520:Plant Shoots / Q000737:chemistry; D012987:Soil / Q000737:chemistry*
chemical_list: D001149:Arsenates; D012987:Soil; D010758:Phosphorus; D001151:Arsenic; C025657:arsenic acid
keywords: Adsorption; Arsenic; Bioavailability; Phosphorus; Variable-charge soil