Element Accumulation Patterns of Native Plant Species under the Natural Geochemical Stress

A biogeochemical study of more than 20,000 soil and plant samples from the North Caucasus, Dzungarian Alatau, Kazakh Uplands, and Karatau Mountains revealed features of the chemical element uptake by the local flora. Adaptation of ore prospecting techniques alongside environmental approaches allowed the detection of geochemical changes in ecosystems, and the lessons learned can be embraced for soil phytoremediation. The data on the influence of phytogeochemical stress on the accumulation of more than 20 chemical elements by plants are considered in geochemical provinces, secondary fields of deposits, halos surrounding ore and nonmetallic deposits, zones of regional faults and schist formation, and over lithological contact lines of chemically contrasting rocks overlain by 5-20 m thick soils and unconsolidated cover. We have corroborated the postulate that the element accumulation patterns of native plants under the natural geochemical stress depend not only on the element content in soils and the characteristics of a particular species but also on the values of ionic radii and valences; with an increase in the energy coefficients of a chemical element, its plant accumulation decreases sharply. The contribution of internal factors to element uptake from solutions gives the way to soil phytoremediation over vast contaminated areas. The use of hyperaccumulating species for mining site soil treatment depends on several external factors that can strengthen or weaken the stressful situation, viz., the amount of bedrock exposure and thickness of unconsolidated rocks over ores, the chemical composition of ores and primary halos in ore-containing strata, the landscape and geochemical features of sites, and chemical element migration patterns in the supergene zone

Landscape monitoring studies of the North Caucasian geochemical province

The data on the geochemical features of the bedrocks and soils of the province are given. Considerable attention is paid to regional abundances, as well as enrichment and dispersion factors of the chemical elements in landscapes. Using the example of the North Caucasus, it is shown that for such indicators as phytomass, geological, geomorphological, and geobotanical features, it is possible to make a preliminary outlining of regional structures corresponding to geochemical provinces. At the same time, a subsequent geochemical study of these structures remains mandatory. Upon determining certain geochemical associations, geochemical provinces can be basically distinguished; to a large extent, geochemical properties of these accumulated and scattered associations of elements contribute to the regional soil geochemistry. The results of long-term monitoring studies of the North Caucasus geochemical province have shown that the key features of the regional landscapes are due to the composition of bedrock and the presence of a large number of ore deposits and occurrences. The data obtained are the basis for assessing the state of the environment in conditions of increasing anthropogenic impact, and the established regional abundances can be used to assess the degree of pollution in agricultural, residential, and mining landscapes

Trace element accumulation by soils and plants in the North Caucasian geochemical province

Long-term studies of the North Caucasian geochemical province allowed to establish regional abundances and calculate accumulation (dispersion) factors for chemical elements in rocks, soils, and plants. Certain natural regional patterns characterize the province. Associations of elements in high and low concentrations are often determined by the predominant composition of rocks: carbonate-terrigenous, terrigenous, and igneous. The study of the average contents of several chemical elements in the soils of the province showed that the association of accumulated elements includes metals with different migration characteristics. Thus, despite the rather close values of the ionic radii, Pb, Zn, Cu, and Li (judging by the ionic potential) are characterized by the formation of cations, while Mn, Mo, and Zr form complex ions. Such elements as Zn, Cu, and Pb are mainly accumulated on hydrosulfuric barriers, while Mo, Co, and Mn are stopped by oxygenous barriers. For Cu, Zn, Mo, and Co, biogenic accumulation plays a significant role, while for Pb and Ni it is practically absent. The absolute dispersion of the elements did not reach environmentally hazardous values, although it indicates a fairly intensive migration. In woody plants, Ba, Nb, Sc, Sr, and Zn are accumulated most intensively

The Modified Weighted Slab Technique: Models and Results

In an attempt to understand the source and propagation of galactic cosmic rays we have employed the Modified Weighted Slab technique along with recent values of the relevant cross sections to compute primary to secondary ratios including B/C and Sub-Fe/Fe for different galactic propagation models. The models that we have considered are the disk-halo diffusion model, the dynamical halo wind model, the turbulent diffusion model and a model with minimal reacceleration. The modified weighted slab technique will be briefly discussed and a more detailed description of the models will be given. We will also discuss the impact that the various models have on the problem of anisotropy at high energy and discuss what properties of a particular model bear on this issue.Comment: LaTeX - AASTEX format, Submitted to ApJ, 8 figures, 20 page

Concentration of essential chemical elements in whole blood and in paranasal sinuses mucosa is related to chronic rhinosinusitis severity in children

Objectives to evaluate the association between essential chemical element levels in whole blood and in pathologic mucosa and chronic rhinosinusitis severity in children. Material and methods. A total of 154 children aged from 6 to 17 years were examined. Among them, 88 children had chronic rhinosinusitis (CRS) and underwent functional endoscopic sinus surgery (FESS). The 66 healthy children were included in the control group. Life quality was assessed using SNOT-20 (Sino-Nasal Outcome Test-20). Endoscopic and computer tomography findings were evaluated using Lund Kennedy and Lund Mackay scales, respectively. The assessment of essential element levels in whole blood samples was performed using inductively-coupled plasma mass-spectrometry. Results. The obtained data demonstrate that total SNOT-20 scores in CRS patients were 68% higher than in controls. At the same time, whole blood calcium, selenium, zinc, and magnesium levels were 6%, 28%, 20%, and 3% lower than the respective control values. The analysis of pathologic mucosa demonstrated that the chemical element contents were reducing in the following order: Ca Mg = Fe Zn Cu Mn Se. However, only whole blood selenium level correlated significantly with its tissue level. In multiple regression models, the whole blood Se level was inversely associated with SNOT-20 and Lund Mackay total scores. Conclusion. Therefore, the obtained data allow to propose the potential role of altered calcium, magnesium, zinc and selenium metabolism in CRS progression

Element Accumulation Patterns of Native Plant Species under the Natural Geochemical Stress

A biogeochemical study of more than 20,000 soil and plant samples from the North Caucasus, Dzungarian Alatau, Kazakh Uplands, and Karatau Mountains revealed features of the chemical element uptake by the local flora. Adaptation of ore prospecting techniques alongside environmental approaches allowed the detection of geochemical changes in ecosystems, and the lessons learned can be embraced for soil phytoremediation. The data on the influence of phytogeochemical stress on the accumulation of more than 20 chemical elements by plants are considered in geochemical provinces, secondary fields of deposits, halos surrounding ore and nonmetallic deposits, zones of regional faults and schist formation, and over lithological contact lines of chemically contrasting rocks overlain by 5–20 m thick soils and unconsolidated cover. We have corroborated the postulate that the element accumulation patterns of native plants under the natural geochemical stress depend not only on the element content in soils and the characteristics of a particular species but also on the values of ionic radii and valences; with an increase in the energy coefficients of a chemical element, its plant accumulation decreases sharply. The contribution of internal factors to element uptake from solutions gives the way to soil phytoremediation over vast contaminated areas. The use of hyperaccumulating species for mining site soil treatment depends on several external factors that can strengthen or weaken the stressful situation, viz., the amount of bedrock exposure and thickness of unconsolidated rocks over ores, the chemical composition of ores and primary halos in ore-containing strata, the landscape and geochemical features of sites, and chemical element migration patterns in the supergene zone

Memory Effect: How the Initial Structure of Nanoparticles Affects the Performance of De-Alloyed PtCu Electrocatalysts?

An important feature of this research is the investigation of the de-alloyed catalysts based on the nanoparticles with a simple structure (alloy) and a complex structure (gradient). The resulting samples exhibit the 2–4 times higher mass activity in the ORR compared with the commercial Pt/C. The novelty of this study is due to the application of the express-electrochemical experiment to register the trend of changes in the ORR activity caused by rearranging the structure of bimetallic nanoparticles. The state-of-the-art protocol makes it possible to establish the dependence of properties of the de-alloyed catalysts on the nanoparticles’ structure obtained at the stage of the material’s synthesis. The study shows the possibility of determining the rate of the ongoing reorganization of bimetallic nanoparticles with different architectures. The PtCu/C electrocatalysts for proton-exchange membrane fuel cells presented in this work are commercially promising in terms of both the high functional characteristics and the production by facile one-pot methods

Memory Effect: How the Initial Structure of Nanoparticles Affects the Performance of De-Alloyed PtCu Electrocatalysts?

An important feature of this research is the investigation of the de-alloyed catalysts based on the nanoparticles with a simple structure (alloy) and a complex structure (gradient). The resulting samples exhibit the 2–4 times higher mass activity in the ORR compared with the commercial Pt/C. The novelty of this study is due to the application of the express-electrochemical experiment to register the trend of changes in the ORR activity caused by rearranging the structure of bimetallic nanoparticles. The state-of-the-art protocol makes it possible to establish the dependence of properties of the de-alloyed catalysts on the nanoparticles’ structure obtained at the stage of the material’s synthesis. The study shows the possibility of determining the rate of the ongoing reorganization of bimetallic nanoparticles with different architectures. The PtCu/C electrocatalysts for proton-exchange membrane fuel cells presented in this work are commercially promising in terms of both the high functional characteristics and the production by facile one-pot methods