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Partitioning of metals in soil particles of various size classes has been receiving greater significance due to the necessity to predict the behaviour and pathways of the potentially toxic elements in the environment. In this study the analysis of metals’ distribution in various particle size fractions was performed to characterize and compare geochemical features of the topsoil horizons of two small erosional landforms located in uncontaminated area of the central part of European Russia (the Middle Protva basin, mixed forest zone). The landforms represent two typical lithological types of gullies in the study area. Soil samples were fractionated and the concentrations of Fe, Mn, Ti, Zr, Ni, Co, Cr, Zn, Cu, Pb were determined in five particle size fractions: 1–0.25, 0.25-0.05, 0.05−0.01, 0.01–0.001 and

Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth's systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SI ≥0.5), very high (SI ≥0.7), and the highest potential (SI ≥0.9) for dust emission cover >1 670 000 km2, >560 000 km2, and >240 000 km2, respectively. In the Arctic HLD region (≥60∘ N), land area with SI ≥0.5 is 5.5 % (1 035 059 km2), area with SI ≥0.7 is 2.3 % (440 804 km2), and area with SI ≥0.9 is 1.1 % (208 701 km2). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50∘ N, with a “transitional HLD-source area” extending at latitudes 50–58∘ N in Eurasia and 50–55∘ N in Canada and a “cold HLD-source area” including areas north of 60∘ N in Eurasia and north of 58∘ N in Canada, with currently “no dust source” area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0 % of the global dust emission originated from the high-latitude regions. About 57 % of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD.

Dust particles emitted from high latitudes (≥ 50° N and ≥ 40° S, including Arctic as a subregion ≥ 60° N), have a potentially large local, regional, and global significance to climate and environment as short-lived climate forcers, air pollutants and nutrient sources. To understand the multiple impacts of the High Latitude Dust (HLD) on the Earth systems, it is foremost to identify the geographic locations and characteristics of local dust sources. Here, we identify, describe, and quantify the Source Intensity (SI) values using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM), for sixty-four HLD sources included in our collection in the Northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and Southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD dust sources show seasonal character. The environmental and climatic effects of dust on clouds and climatic feedbacks, atmospheric chemistry, marine environment, and cryosphere-atmosphere feedbacks at high latitudes are discussed, and regional-scale modelling of dust atmospheric transport from potential Arctic dust sources is demonstrated. It is estimated that high latitude land area with higher (SI ≥ 0.5), very high (SI ≥ 0.7) and the highest potential (SI ≥ 0.9) for dust emission cover >1 670 000 km2, >560 000 km2, and >240 000 km2, respectively. In the Arctic HLD region, land area with SI ≥ 0.5 is 5.5 % (1 035 059 km2), area with SI ≥ 0.7 is 2.3 % (440 804 km2), and with SI ≥ 0.9 it is 1.1 % (208 701 km2). Minimum SI values in the north HLD region are about three orders of magnitude smaller, indicating that the dust sources of this region are highly dependable on weather conditions. In the south HLD region, soil surface conditions are favourable for dust emission during the whole year. Climate change can cause decrease of snow cover duration, retrieval of glaciers, permafrost thaw, and increase of drought and heat waves intensity and frequency, which all lead to the increasing frequency of topsoil conditions favourable for dust emission and thereby increasing probability for dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify and assess the environmental and climate significance of HLD in the future.

We investigated the vertical and spatial distribution of chemical elements (ChEs) in four cross-sections within a catena formed in typical southern taiga on Retiosols , underlying loess loams and carbonate moraine deposits. Catena located in the Tver' region (Russia). In plants (70 samples, 19 species) and soils (31 samples), the total content of the ChEs was determined by mass spectrometry. In soil samples, we measured pH, grain size and levels of ChE mobile fractions (exchangeable (F1), bound to organic complexes (F2) and bound to Fe and Mn hydroxides (F3).In the A-horizons the average total concentration of Fe is 1,2%, Ti – 0,33%; Mn – 482 mg‧kg-1, Zr–292, Sr–90, Zn–39, Cr–21, Pb–21, Ni–9, Cu–8. The concentration of metal F1 diminishes in order: Fe>Mn>Sr>Zn, Pb>Ti, Cr, Ni, Cu, Co, Zr. The concentrations of F2 and F3 show the following order: Fe>Mn>>Ti, Zr, Pb>Co>Ni, Cu, Zn>Cr, Sr and Fe>Mn>Ti>Zn, Sr, Pb>Cr>Cu, Ni, Co>Zr, respectively.In all studied Retisols, vertical distribution of the total Pb and Zr, F1 of Co, Fe, Mn, Pb and Zn, F2 of Cu, Fe, Pb and Zn, F3 of Pb accumulate in topsoil. For the total Co, Fe, Ni, Sr and Zn, F1 of Co, Cr, Cu, Mn, Pb, Zn and Zr, F2 of Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Zr and F3 of Co, Cr, Cu, Ti, Zn, Zr the loss from the albic horizons and/or the accumulation in the argic horizons were registered.Spatial distribution of the total concentration of ChEs increases in the A-horizon in the upper part of the catena slope position. In the A-horizons at footslope and toeslope positions, the concentration of F1 Ni, Cu, Sr and Zr, F2 Ni, Cu and Zn increases, and the concentration F2 of Co, Cr, Pb, Ti and Zn, F2 of Cr, Ti and Co, F3 of Mn, Ni, Zn, Pb, Zr decreases.Ratios calculated on the basis of the total and mobile element content were applied to evaluate biogenic migration of ChEs with different biophilicity in the "plant-soil" system. According to soil-to-plant transfer ratios, Mn, Zn and Cd are actively involved in biological accumulation. Participation in biological accumulation of Mn and Zn was noted in many works (Avessalomova, 2007; Isachenkova, Tarzayeva, 2006, Kadata-Pendias, Szteke, 2015)Mn and Zn have important physiological significance in plants; they actively migrate in plant tissues. Cd is not a necessary ChEs for plants but is easily absorbed by the root system and leaves (Kabata-Pendias, 2011). Cationic elements (Cd and Zn) have high mobility in the soils (Jen-How Huang, 2011). Our results indicate that in the reference forest communities, tree species play the major role in the uptake and turnover of biophilic microelements (Mn, Zn, Co) while sphagnum moss and grassy covers mostly absorb the elements with low biophilicity (Fe, Ti, Cr, Zr, Pb). Metabolic pathways carry out the absorption of Fe and Cr (Kabata-Pendias, 2011).

For an improved understanding of metal behavior in soils, studies on geochemical changes occurring in a specific grain-size fraction during pedogenesis and lateral translocation of soil material are needed. In the present research we analyzed the concentrations and vertical distributions of Fe, Mn, Cu, Ni, Co, Cr, Zn, Pb, Ti, Zr in coarse and medium sand fraction of the major soil types of the middle Protva basin, situated in the mixed forest zone of European Russia, and described patterns of downslope (lateral) distribution of metals in the humus horizons along two catenas and two types of small erosional systems. The observed concentrations for all metals in the fraction 1–0.25 mm, except of Mn, conform to the natural geogenic concentrations reported previously in literature. The majority of the metals exhibit high natural variability in concentrations in the sand fraction. Higher metal concentrations are found either in the topsoil horizons or in parent material and underlying stratum. Studying lateral aspects of metal distribution in the sand fraction of humus horizons revealed a decrease in Mn, Zn, Pb, Co, Ti and an increase in Fe, Cr and Ni levels of the lower sections of the slopes. The similarity of metal concentrations in the sand fraction in these positions across two catenas implies the importance of the geochemical convergence processes operating in downslope direction. The small erosional landforms, a gully and a dry U-shaped valley, show similar patterns in lateral distribution of Fe, Cu, Ni, Cr, Zr, Zn, but they differ in terms of Pb, Co and Mn behavior across their elementary units: adjacent areas, slopes and bottom. The results imply that the features of vertical (within the soil profiles) and lateral (along catenas and small erosional systems) distributions of metals are significantly controlled by the provenance of the sand fraction, although at the same time some variations in metal contents seem are attributed to chemical transformations of the sand fraction due to pedogenic processes and during downslope translocation of soil material.

Small erosional landforms, despite their importance in mass transfer processes, have received insufficient attention in geochemical studies. This paper presents a case study dealing with geochemistry of two small erosional systems, typical of humid moraine landscapes of the central part of European Russia. They are considered as integrated systems comprising several units viz. slopes, bottoms, detrital fans as well as adjacent areas as sources of solid material. Chemical composition of topsoil (total concentrations of Ti, Zr, Mn, Co, Zn, Cu, Pb, Cr, V, Ni, Sn, Sr, Ba and concentrations of the acid-extractable Fe, Mn, Co, Zn, Cu, Pb, Cr, Ni) was used to explore the role of granulometry, pH, organic matter content and transport processes in geochemical differentiation of the systems. Spatial variations in granulometry across the various units indicate a progressive depletion of a finer material in the gully and comparatively invariant distribution of the same fractions within the balka. The granulometry is the main factor controlling the distribution of total and acid-extractable metal concentrations in both systems. The findings imply that the prevailing mechanism of metal migration through the studied systems is a suspension transfer in association with clay and silt particles. The young gully system operates as a transit system and shows higher geochemical differentiation than the aged balka system where some elements may accumulate in topsoil of the lower units of this system.