Sorption of iodine in soils: insight from selective sequential extractions and X-ray absorption spectroscopy

Multiple geochemical factors may cause iodine and selenium deficiency in Gilgit-Baltistan, Pakistan

“…The input to soil I T from irrigation water is likely to be minimal because of the low concentration of I in water sources. Furthermore, the soils are predominantly sandy with low organic carbon concentrations, which limits the ability of the soils to retain I (Johnson, 2003 ; Johnson et al, 2003 ; Köhler et al, 2019 ; Mohiuddin et al, 2019 ; Watts & Mitchell, 2009 ; Watts et al, 2019 ). The alkaline nature of the soils would also limit I retention; adsorption of I onto Fe and Al oxyhydroxides and rates of conversion to humus-bound I, are both lower under alkaline conditions (Johnson et al, 2003 ; Shetaya et al, 2012 ; Söderlund et al, 2017 ; Wang et al, 2019 ; Watts & Mitchell, 2009 ).…”

Impact of abiotic and biogeochemical processes on halogen concentrations (Cl, Br, F, I) in mineral soil along a climatic gradient

“…6,8,14 In the forest oor and organic-rich topsoil, biotic and abiotic halogenation processes occur that incorporate Cl, Br and I into organic matter. [15][16][17][18] At the same time, biological processes include dehalogenation, 2,8,17,19 increasing in turn the mobility and therefore vertical displacement of halogens into the mineral soil. Because the biophilic halogens Cl, Br and I are correlated with organic matter owing to xation by halogenation processes, highest concentrations can be expected for the forest oor and the topsoil, where the concentration of organic matter is highest.…”

“…5,25,26 The mobility of halogens in soil is further reected by the proportion of labile inorganic halides; the lower it is, the stronger is the respective halogen retained in a certain part of the soil. 18 So far, only few data for the depth distribution of total halogens and/or labile halides in soils of pristine ecosystems are available. 7,11,13,20 1…”