Iodine Concentration,Chemical Speciation And Their Distribution In Atmospheric Precipitation And Soil

The iodine is the essential element of the human and mammals, the insufficient iodine intake will cause iodine deficiency disorders (IDD).China is one of the countries where IDD is the most widely distributed in the world. The key problem of IDD origin is the phytoavailability of iodine in environment. In this research, we gain field sampling and analysis the soil iodine content, chemical speciation and their distribution; In the typical area of china,we have atmospheric precipitation and surface water samples, and determine their total water iodine, iodide, iodate, and anion-cation content, On the basis of source analysis model, we study the source of iodine in the atmosphere. The main conclusions are as follows:1、Soil iodine content is not completely controlled by the distance from the sea:In Ju County Shandong Province located in coastal (Guxicun, Qianshiyao) soil iodine levels is even lower than inland Guizhou Province Zhijin County (Shuiyicun,Jingjiaocun,Shuitangcun,Shuiyanba)andGuiyang (Alicun,Caobacun).2、Soil forming rock have important influence on soil iodine content, soil iodine content of limestone region is higher than other adjacent rocks area(granite, sandstone, dolomite).3、In atmospheric precipitation,the iodate proportion is0～0.55%, and the iodide ratio is0.40～7.04%, the organic iodine ratio is95.13～99.31%. In the atmospheric environment,the most stable iodine form in chemical thermodynamics is iodate which is the lowest content, we need reviewing iodine atmosphere geochemical behavior.4、In surface water, iodate ratio is0～2.80%, and the iodide ratio is0.46～5.08%, organic iodine ratio is93.92～99.53%.5、In addition to zibo, in atmospheric precipitation iodate content is significantly higher than in surface water; in the others point, in surface water iodate content is higher than in atmospheric precipitation. After rain (snow) water landing surface, some organic iodine on the surface transforms into iodate under the action of biological geochemistry.6、Atmospheric precipitation has an important contribution to source of iodine from the surface water, in different areas,iodine geochemical behavior has a bigger difference, in surface water iodine content higher than in atmospheric precipitation shows that additional iodine solution out of soil and other surface environment and into the water, and in surface water iodine content lower than in atmospheric precipitation indicates that the iodine in atmospheric precipitation is absorbed by surface soil and plants.7、Sea salt tracer analysis shows that iodine contribution through sea water directly volatile, splash of atmospheric is less than1%, Apart from the ocean in100km distance, in atmospheric precipitation Marine contribution of sea water splash and direct volatile has no significant difference; Source of calcium tracer analysis shows that in atmospheric iodine the crust sources contribution is less than35%; Apart from the ocean in100km distance, the contribution of ocean to iodine of the surface environment is mainly through the iodine atmosphere geochemical cycle, namely in the photochemical and biogeochemical function, sea water iodine volatiles directly into the atmosphere in the form of gaseous iodine, contribution of the ocean to the surface environment is small, therefore distribution more "uniform".8、In Sanming atmospheric precipitation iodine content is significantly higher than other regions, confirmed that human emissions has an important contribution in the earth’s local surrounding,and its controlling effects.