Socio-demographic characters, distribution and transformation of iodine in soil, plant and wheat grains at District Diamer, Gilgit-Baltistan, Pakistan

Spatial variation in iodine content with relation to soil physicochemical properties in lower Himalayan region

Topography of a place has a significant impact on soil characteristics that ultimately influence soil iodine levels. Lower Himalayan region (LHR) in Pakistan has a wide range of climatic and geological variations. Hence, an investigation was conducted to analyze the iodine concentration and other physicochemical properties of soils in two LHR districts, Haripur and Mansehra. Spatial analysis indicated a decrease in iodine levels in the mountainous regions in comparison to the flat portions of LHR. Soil samples obtained from different locations across Haripur had a stronger affinity for iodine due to variations in solubility and adsorption of iodine to soil clay components, which can be attributed to lower pH, higher organic matter, and a higher cation exchange capacity (CEC). In contrast to the plains of Haripur, elevated locations in the Mansehra district had decreased levels of iodine, along with a higher soil pH and reduced soil organic matter. The soil erosion and depletion of soil micronutrients in the hilly region of Mansehra may be attributed to the unfavorable soil conditions and excessive precipitation. Presence of clay, iron (Fe), and aluminum (Al) in the soil led to a rise in iodine levels. Iodine concentrations exhibited an inverse relationship with soil acidity. Study revealed a direct correlation between soil iodine levels and their cation exchange capacity (CEC) and clay content. This study aims to gather fundamental data for the chosen regions of LHR to address illnesses caused by iodine deficiency.

Iodine supplementation through its biofortification in Brassica species depending on the type of soil

Iodine is an essential microelement for humans and its deficiency leads to iodine deficiency disorder (IDD) which is a common problem faced by people in hilly areas. Biofortification of iodine is an option to overcome the IDD problem. Herein, we investigated the iodine uptake and accumulation in the edible portion of vegetables such as Brassica napus (BNP) and Brassica pekinensis (BPK) which were grown on two different soils such as sandy soil (SS) and silty loam soil (SLS) with different concentrations of iodine application (used in sodium iodide form) such as 0 ppm, 50 ppm, and 100 ppm. The concentration of iodine was determined by the oxidation of iodide, and nutrients were examined by double acid digestion. Different concentrations of iodine were noticed in silty loam and sandy soils, roots, and shoots of BNP and BPK, while the concentration follows the order: soils > roots > shoots. Iodine concentrations in the roots of BNP and BPK ranged from 46 to 223.7 μg/g which shows a strong correlation with other soil nutrients. Moreover, a large amount of iodine was lost due to the leaching. It is concluded that the biofortification of iodine increases its concentration in Brassica species. This work provides a reference for the iodine biofortification in plant species which will be helpful to control IDD.

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

Deficiencies of the micronutrients iodine and selenium are particularly prevalent where populations consume local agricultural produce grown on soils with low iodine and selenium availability. This study focussed on such an area, Gilgit-Baltistan in Pakistan, through a geochemical survey of iodine and selenium fractionation and speciation in irrigation water and arable soil. Iodine and selenium concentrations in water ranged from 0.01-1.79 µg L-1 to 0.016-2.09 µg L-1, respectively, which are smaller than levels reported in similar mountainous areas in other parts of the world. Iodate and selenate were the dominant inorganic species in all water samples. Average concentrations of iodine and selenium in soil were 685 µg kg-1 and 209 µg kg-1, respectively, much lower than global averages of 2600 and 400 µg kg-1, respectively. The 'reactive' fractions ('soluble' and 'adsorbed') of iodine and selenium accounted for < 7% and < 5% of their total concentrations in soil. More than 90% of reactive iodine was organic; iodide was the main inorganic species. By contrast, 66.9 and 39.7% of 'soluble' and 'adsorbed' selenium, respectively, were present as organic species; inorganic selenium was mainly selenite. Very low distribution coefficients (kd = adsorbed/soluble; L kg-1) for iodine (1.07) and selenium (1.27) suggested minimal buffering of available iodine and selenium against leaching losses and plant uptake. These geochemical characteristics suggest low availability of iodine and selenium in Gilgit-Baltistan, which may be reflected in locally grown crops. However, further investigation is required to ascertain the status of iodine and selenium in the Gilgit-Baltistan food supply and population.