Soil column experiments for iodate and iodide using K-edge XANES and HPLC–ICP-MS

Iodine soil dynamics and methods of measurement: a review

“…The biogeochemical cycling of iodine in soils is controlled by soil characteristics that affect retention against leaching, such as pH and the concentration of organic matter and metal oxides, and factors related to external iodine inputs, such as proximity of the soil to the coast. [17][18][19][20] Partly due to issues regarding the analytical detection of various iodine species, the understanding of soil-iodine reactions and plant uptake mechanisms are still limited. 21,22 The average iodine concentration in the Earth's crust is 0.25-0.45 mg kg -1 , whilst the average soil concentration is significantly higher at 5.1 mg kg -1 .…”

“…34 Soluble iodine exists predominantly as iodate, iodide and org-I: the proportions of these are influenced by soil characteristics and probably contact time. [17][18][19] There is substantial evidence demonstrating that when iodide and iodate are added to soils they are rapidly converted to org-I within minutes-to-days and days-to-weeks, respectively. 34,36,37,42,45 Within acidic soils, inorganic iodate may be reduced to elemental iodine and iodide; in soils with pH >6, organic matter has a greater influence on iodine sorption compared to Fe/Al oxides.…”

“…In flooded anoxic soils iodide is the dominant inorganic species, however, in oxidising conditions iodate is more likely to be the stable inorganic species. 19,48 Once in the terrestrial environment iodine is highly mobile; iodine present in the soil-plant system can be (re-)volatised into the atmosphere. Amiro and Johnston 49 speculated that iodine volatilised from plants is primarily released as methyl iodide, but emissions from living vegetation might only contributẽ 0.1% to the stable iodine concentration in the surrounding atmosphere.…”

“…Soluble iodine exists mainly as IO3 − , I − and org-I, and the proportions of these species present are significantly influenced by soil properties. [17][18][19] Iodine speciation analysis, in solution, can be performed by gas chromatography, high performance liquid chromatography, size exclusion chromatography, and electrospray ionisation, whilst synchrotron light source analysis can determine iodine species in a solid matrix. 19,35,37,122,123…”

“…Shimamoto, et al 19 investigated the mobility of iodide and iodate in soil pore water of paddy field soils using HPLC-ICP-MS. Soil columns (10.7 cm) were incrementally packed and pressed with a 2.0 kg weight the ensure uniform bulk density, the treatment consisted of applying 80 mL of Milli-Q water and then 50 mL of a treatment solution.…”