title: Organic matter-solid phase interactions are critical for predicting arsenic release and plant uptake in Bangladesh paddy soils.
abstract: Agroecological zones within Bangladesh with low levels of arsenic in groundwater and soils produce rice that is high in arsenic with respect to other producing regions of the globe. Little is known about arsenic cycling in these soils and the labile fractions relevant for plant uptake when flooded. Soil porewater dynamics of field soils (n = 39) were recreated under standardized laboratory conditions to investigate the mobility and interplay of arsenic, Fe, Si, C, and other elements, in relation to rice grain element composition, using the dynamic sampling technique diffusive gradients in thin films (DGT). Based on a simple model using only labile DGT measured arsenic and dissolved organic carbon (DOC), concentrations of arsenic in Aman (Monsoon season) rice grain were predicted reliably. DOC was the strongest determinant of arsenic solid-solution phase partitioning, while arsenic release to the soil porewater was shown to be decoupled from that of Fe. This study demonstrates the dual importance of organic matter (OM), in terms of enhancing arsenic release from soils, while reducing bioavailability by sequestering arsenic in solution.
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, England. p.n.williams@lancaster.ac.uk
authors.forename: Paul N
authors.initials: PN
authors.lastname: Williams
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: William
authors.initials: W
authors.lastname: Davison
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Meharg
authors.forename: Mahmud
authors.initials: M
authors.lastname: Hossain
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Norton
authors.forename: Hugh
authors.initials: H
authors.lastname: Brammer
authors.forename: M Rafiqul
authors.initials: MR
authors.lastname: Islam
mesh_terms: D000383:Agriculture; D000704:Analysis of Variance; D001151:Arsenic / Q000737:chemistry / Q000493:pharmacokinetics*; D001459:Bangladesh; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D004058:Diffusion; D006812:Humic Substances / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D012275:Oryza / Q000378:metabolism*; D025341:Principal Component Analysis; D012044:Regression Analysis; D012987:Soil / Q000032:analysis*; D014872:Water Movements
chemical_list: D006812:Humic Substances; D012987:Soil; D001151:Arsenic