The distribution of natural radionuclides 40K, 228Ac, and 226Ra on Romanian Territory: a radiometric study

To estimate the radiation hazard due to the natural terrestrial radioactivity, 598 samples of soil covering the entire Romanian territory were collected and analyzed for the distribution of natural radionuclides 40K, 228Ac, and 226Ra. The ultra-low background Slanic-Prahova underground laboratory was used to determine the gamma-ray-specific activity of these radioactive isotopes with an uncertainty between 5 and 20%. All these data permitted to establishing a set of 2D maps illustrating the distribution of specific activity of each radionuclide as well as of the resulting air dose rate, all of them illustrating an heterogeneous distribution, increased values being displaced on the western and south-western territory. Mediated over 598 points, these determinations led to a value of annual effective dose of 0.7 ± 0.15 mSv/y and an external hazard index of 0.46 ± 0.1, both attesting to a radioecologically safe environment for human activity.

Concentration and mobility of trace elements (Li, Ba, Sr, Ag, Hg, B) and macronutrients (Ca, Mg, K) in soil-orchid system on different bedrock types

The mobility of chemical elements in the soil-orchid system has been poorly studied. The aim of this study is to evaluate the uptake and mobility of several trace (Li, Ba, Sr, Ag, Hg, and B) and macronutrients (Ca, Mg, and K) in the orchid Anacamptis morio (L.) R.M.Bateman, Pridgeon & M.W.Chase from soils in western Serbia. The sampling sites are characterized by three different bedrock types-cherts, limestones, and serpentines, which are the source of the significant chemical differences in the elemental status of the soil and plant tissues. The four-step Community Bureau of Reference sequential extraction procedure was used to determine the distribution of fractions and predict their potential phytoavailability. The orchid and soil samples were analyzed for total elemental content analysis using ICP-OES. The greatest potential for plant availability was determined for Ba and Sr, representing about 80% of the total soil content. More than 40% of Li in the soils was found to be potentially phytoavailable. Significant correlations were found between the total content of Li, B, and Sr in soils. Between 38 and 60% of Li content and more than 80% of Ba and Sr content were determined to be potentially phytoavailable by sequential analysis. The highest bioconcentration factor (> 1) was determined in the case of B and Sr for all orchid organs, while translocation factor for Li was highest in tubers and leaves. The studied elements were mainly stored in tubers and roots, indicating the exclusion strategy of A. morio as a metal tolerance mechanism. The data obtained showed significant differences in metal content in soils and plants originating from sites with different parent materials, suggesting that bedrock type and associated soil properties are important factors that determine chemical element mobility and uptake.

Vertical distribution and major influencing factors of soil selenium in tropical climate: A case study of Chengmai County, Hainan Island

Soil selenium is of great significance to human health. Soil-forming parent rocks are the most critical factor that influences soil Se levels. Chengmai County, Hainan Island, has a tropical climate and diverse types of parent rocks, in which soil Se content is high. This study investigated the vertical distribution of soil Se from various parent rock substrates under tropical climatic conditions, and the factors that influence these soil Se contents, with 69 vertical soil profiles covering Chengmai County. The vertical distribution of soil Se and correlations with CIA (chemical alteration index), Al₂O₃, TFe₂O₃ (total iron oxide expressed as Fe₂O₃), total iodine, SOC (soil organic carbon), and pH were analysed. As per the results, the mean ± standard error of Se content in the A, B, and C horizons was 0.88 ± 0.13 mg/kg, 0.77 ± 0.08 mg/kg and 0.45 ± 0.05 mg/kg, respectively. The parent rock strictly controlled the horizon distribution of Se in the A-horizon. Soil Se showed A-B-horizons-enrichment in the vertical profile, especially in soil profiles overlying granite and basalt. It is hypothesised that the Se enriched in soils developed from the Tuolie Formation due to the release of Se from the weathering process of Se-rich rocks. Meanwhile, Se in soils developed from granite and basalt is more closely associated with exogenous input. Another crucial factor for the high level of Se in Chengmai County is the tropical climate, which has led the rocks to generally undergo intense chemical weathering. This results in soils rich in clay minerals and Fe/Al oxyhydroxides, which easily absorb and retain Se. Furthermore, the Se content of the B-horizon was generally higher than that of the A-horizon due to leaching. These results provide further knowledge and understanding of the geochemical behaviour of soil Se and guide the evaluation of Se-rich land resources under tropical climatic conditions.

Spatial distribution and environmental impact factors of soil selenium in Hainan Island, China

Selenium is an essential micronutrient for the human body, given its various health benefits. However, Se deficiency is widespread globally, and dietary adjustment is a feasible way to supplement people's Se daily intake. The Multi-purpose Regional Geochemical Survey (NMPRGS) conducted in Hainan Island found an abundance of Se-rich soil. These Se resources have been utilized to grow naturally Se-rich produce. However, insufficient research has been conducted into the spatial distribution and enrichment of soil Se in Hainan Island. This paper analysed the effect of the environmental impact factors (parent rock, precipitation, etc.) on soil Se, using data from the NMPRGS database. The results showed that, in comparison to the baseline value of Chinese soil, the enrichment degree of Se in the topsoil of Hainan Island was higher, but its distribution was uneven. The parent rock, precipitation, soil type, and soil characteristics all affect the concentration and spatial distribution of regional soil Se. Geographically weighted regression showed that Iodine, pH, SOC, and TFe₂O₃ have a non-stationarity spatial relationship with Se. There was a significant correlation between soil Se and Chemical alteration index (CIA) in granite areas, while CIA was also related to mean annual precipitation (MAP). The concentration enrichment factor values of Se show that the external input of Se in high MAP areas is significantly higher than that in low MAP areas. Based on these results, three important environmental impact factors on soil Se enrichment at the regional scale in Hainan Island were defined: 1) Se-rich rocks; 2) precipitation; 3) SOC. These results can provide guidance for the planning and layout of Se-rich agriculture.

Essential differences in the mineral status of free-ranging European bison Bison bonasus populations in Poland: The effect of the anthroposphere and lithosphere

Tracking the concentration of elements in the organs of endangered animal species can provide significant knowledge about environmental hazards and allows more targeted protective measures to be taken. In this paper the differences in concentrations of 27 elements in the livers of free-ranging European bison were studied. The ICP-OES method was applied to study the four main Polish populations, which live in lowland (Białowieska, Knyszyńska and Borecka forests) and mountain (Bieszczady) habitats. The study was based on a unique and relatively large amount of comparative material. It was found that European bison populations that live in different locations differ from each other in terms of the hepatic concentrations of 17 of the elements studied in this work. The mountain population in Bieszczady was most distinctive due to the higher concentrations of Ba, Ca, Cd, Se, and the lower concentrations of Mo and V (compared to the other populations). Additionally, even geographically close lowland populations sometimes have different hepatic concentrations of particular elements. The sex and age of individuals have a weak effect on mineral status. Although the lithosphere is the primary factor that affects the availability of elements for the European bison, the soil parameters and biosphere can significantly affect the availability of elements, e.g. by accumulation. It was also shown that the anthroposphere plays a role, but this is mainly through agriculture as feeding on arable fields significantly changes the mineral status of European bison. The need for further research, especially on Cd, Se and Cu, was indicated. It was concluded that toxic elements or deficiencies in essential elements in the populations of the studied species should be considered locally as this would allow better understanding of the health condition of individual populations.