Cartographic evaluation of the risk of natural elements' deficiency in the soil cover provoking spatial variation of the endemic morbidity level (on example of thyroid morbidity among population of the Central Federal District, Russia).

The main goal of the study is to evaluate the contribution of the natural geochemical risk in the central part of the Eastern European Plain to the spatial distribution of human diseases provoked by the deficiency of biologically significant microelements (Co, Cu, and I) in the environment. The Central Federal District (CFD) of Russia, located in the Eastern European Plain is characterized by a deficiency of Co, Cu, and I in the environment (soils, local food). To access the risk of thyroid diseases associated with Co, Cu, and I content in soils of the CFD based on published data of trace elements concentrations and digital soil map we create maps of the elements variation in soil cover allowing to estimate their mean concentration in the regions. The obtained cartographic estimates are comparable with the previously published assessments and averaged study results at the regional level. Comparison with medical data on thyroid disease morbidity from 2013 to 2017 at the regional level showed a significant inverse correlation with the cartographic estimates of soil I and combined (Co + Cu + I) status with due consideration of soil structure (12 regions, except for those affected by technogenic radioiodine contamination and Moscow urbanized regions). The urban population suffered from thyroid diseases to a higher extent in comparison with the rural population, which corresponds to our previous estimates. The results confirmed the possibility of assessing the geochemical risk of endemic diseases based on geochemical soil maps and identifying the negative contribution of micronutrient deficiency in the environment to endemic morbidity in the population.

On the ordered nature of redistribution of technogenic elements in undisturbed elementary landscape-geochemical systems of the temperate zone on the example of the Chernobyl 137Cs fallout.

The study is aimed at identifying patterns in distribution of pollutants in the elementary landscape-geochemical systems (ELGS) of the temperate zone. The study used 137Cs as a tracer, which allows a highly detailed analysis of the nature of the heterogeneity of secondary migration in the toposequence: summit-slope-closing depression, treated as the elementary landscape-geochemical system. The study site was located in the Bryansk region in the Chernobyl abandoned area with an initial level of 137Cs contamination exceeding 1480 kBq/m2 (40 Ci/km2). An original technique of repeated 137Cs measurements along cross-sections accompanied by topographic survey and soil cores sampling has been applied. The obtained results showed a complete absence of constant increase of 137Cs concentration downslope but revealed a steady regular variability of 137Cs activity of a cyclical type. Given uniformity of the initial 137Cs fallout within a small-sized plot, variation of 137Cs due to its secondary distribution in ELGS was 2-2.7-fold according to field gamma-spectrometry data which corresponded to the radionuclide contamination density of the top 20-cm layer of the soil containing 96-99% of the total radionuclide amount (correlation between the parameters equaled to r0.01 = 0.782, n = 20). A specifically regular structure obviously formed under the set of radionuclide water migration processes seems to be inherent in all systems of the studied type. The results obtained are believed to be of both theoretical and practical importance, since they can contribute to making decisions on the precise monitoring of zones of technogenic accumulation, as well as solving fundamental problems of soil formation and its restoration after technogenic pollution.

Chemical composition of groundwater used for drinking in conditions of natural deficiency of iodine and selenium and evaluation of its health effect: the case of Bryansk region (Russia).

Chemical composition of drinking water was examined in rural settlements of Bryansk region to reveal its influence on distribution of endemic thyroid diseases among population after the Chernobyl accident (1986) with due regard to different sources of water, the age and composition of water-bearing rocks. Groundwater samples (n = 515 in total) were collected in 156 rural settlements over the region in the period from 2007 to 2017 and analyzed for major cationogenic elements (Ca, Mg, Sr, K, Na, Mn, Zn, Fe, Al, Si) and anions (HCO32-, Cl-, F-, SO42-, NO32-, PO42-) as well as for I- and Se using ICP-AES, potentiometry, photometry and spectrofluorimetry. The results confirmed a low supply of water samples with iodine (Median (Me) = 5.96 µg/L, variation range 0.06-41.2 µg/L) and selenium (Me = 0.18 µg/L, variation 0.001-6.21 µg/L). The concentration levels of iron (64% of examined districts), manganese (36% of examined districts) and strontium (8% of examined districts) appeared to be inconsistent with hygienic standards. The data on chemical composition of drinking water were analyzed for correlation with the medical data on the prevalence of endemic thyroid diseases among the population living in the corresponding rural settlements. Tendencies of relationship between water iodine concentration and the incidence of thyroid diseases caused by iodine deficiency among teenagers aged 8 to 12 have been found. The same trend was found when comparing geochemical data with iodine content in renal excretion in this age group. The influence of some other components of natural waters on the manifestation of thyroid insufficiency has been cartographically assessed.