Displays

The main factors for the degradation of the ecosystems in the metal-polluted territories are soil toxicity, organic matter degradation and violation of macro-element cycles. Heavily contaminated soils lose their ability to maintain sustainable vegetation, which leads to the formation of industrial barrens as the final stage of plant cover digression, where the vegetation cover is less than 10%. The deposition of metal mobile compounds into an insoluble form by alkaline sorbents is one of the most effective remediation techniques in situ. Technosol engineering is a trigger for the beginning of plant and soil cover development and the recovery succession under high pollution with metals compounds.

Field experiment of remediation using three types of serpentine mining wastes, expanded vermiculite and grass seeds mixture was laid down in 2010-2013 in the impact zone of the copper-nickel ore processing enterprise on the Kola peninsula (northern Europe) beyond the Arctic Circle at two sites with podzol and peat soil. The results obtained in 2019 showed that the immobilization effect was strengthened by high pH inherited from the alkaline wastes making Technosols a geochemical barrier. For the first 5-8 years of the experiment, the Technosol upper layers primary consisted of serpentine minerals, accumulated more than 1 g·kg-1 Ni and 0.1 g·kg^-1 Cu which are constantly deposited from the atmosphere as a result of the Cu-Ni enterprise activity. They also affected the underlying soil and neutralized the most toxic water-soluble and exchangeable fractions of Cu and Ni. Grass growing and litter deposition (in total 4.5-6 kg·m^-2) during the experiment term led to the accumulation of organic carbon by serpentine minerals about 1.5%. Organic matter accumulation also played a significant role in metal binding by upper Technosol layers. Summarily, the remediation technology through the use of serpentine-reached mining wastes bound metals emitted by smelter into insoluble forms, reduced the toxicity of water-soluble and exchangeable fractions of heavy metals and promoted the sustainable development of plant cover.

Research was carried out with the support of the Russian Science Foundation grant 19-77-00077.

How to cite: Slukovskaya, M., Kremenetskaya, I., Drogobuzhskaya, S., Ivanova, L., Novikov, A., and Mosendz, I.: Serpentine-reached mining wastes as a geochemical barrier for the soil remediation under the ongoing Cu-Ni pollution in the Russian Arctic, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-526, https://doi.org/10.5194/egusphere-egu2020-526, 2020.

Source identification and apportionment of heavy metals (HMs) has been a vital issue of soil contamination restoration. In this study, qualitive approaches (Finite mixture distribution model (FMDM) and raster based principal components analysis (RB-PCA)) as well as quantitative approach (positive matrix factorization (PMF)) were composed to identify and apportion sources of five HMs (Cd, Hg, As, Pb, Cr) with the help of several crucial auxiliary variables in Wenzhou City, China. The result of FMDM showed Cd, and Pb fitted for single log-normal distribution, while Hg fitted for double log-normal mixed distribution, and As, Cr presented triple log-normal distribution. Each element was identified and separated from natural or anthropogenic sources. An improved score interpolation map of PCA attached with corresponded auxiliary variables analysis suggested three main contribution sources including parental materials, mines exploiting and industrial emissions contributes most in the whole study area. Each element was further discussed for quantitative contributions through PMF model. Parental materials contributed to all elements (Cd, Hg, As, Pb, Cr) as 89.22%, 84.81%, 7.31%, 35.84%, 27.42%. Industrial emissions had a contribution as 2.94%, 80.77%, 15.93%, 4.79%, 25.63% for each element respectively. While Mine exploiting mixed with fertilizers inputs has dedicated for such five HMs as 7.84%,11.92%, 48.23%, 10.40% and 46.95%. Such results could efficiently be devoted to scientific decisions and strategies making regarding HMs pollution regulation in soils.

How to cite: Shao, S., Hu, B., Zhou, Y., and Shi, Z.: Comprehensive Source Identification and Apportionment Analysis of five Heavy Metals in Soils in Wenzhou City, China , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2514, https://doi.org/10.5194/egusphere-egu2020-2514, 2020.

In megacities, the environment experiences a high anthropogenic press caused by emissions from vehicles and industrial enterprises. Soils are an important component of urban landscapes: they not only accumulate pollutants, but also can be a source of secondary pollution of atmosphere and groundwater. The aim of this work is to analyze the long-term dynamics of soil contamination with potentially toxic elements (PTEs) in Moscow, as Moscow is one of the most polluted cities of Russia.

The basis for assessing the pollution of soils with As, Cd, Pb, Zn, Hg, Cu, Ni, Mn was the annual monitoring data for 2007-2016, which is obtained by the «Mosecomonitoring» institution and include more than 2000 points of observation. The accumulation of PTEs was characterized by a technogenic concentration factor Kc=Curb/Cb relative to the background Cb, which differed by three physiographic provinces. The total geochemical load on soils was estimated as Zc=∑Kc–(n–1), where n is the number of elements with Kc>1.

An analysis of the changes in the pollutant content in the soils of Moscow over the decade showed a twofold increase in the accumulation of Cu, Cd, As in the Central District and Cd in the Western and Northwest ones, as well as As in the northeastern part of the city by 1.4–2.3 times. In all districts, a tendency toward a decrease in pollution with Zn, Pb, and Hg was revealed. Compared with 2007, in 2016, the average content of all PTEs in the soils of the city decreased or remained unchanged, except for As.

The spatial distribution of PTEs in Moscow soils is controlled by the intensity and geochemical specialization of pollution sources, and varies due to soil properties. Central, Eastern, South-Eastern Districts are leading in terms of Cu and Pb pollution. Central and South-Eastern Districts are distinguished by Hg pollution. Central, North-Eastern, South-Eastern, and Southern Districts are most polluted with Zn and Cd. Soils in the southern part of Moscow are most enriched in Ni. High concentrations of As are characterized by soils of light grain-size composition with a high content of organic matter.

The highest values of the total soil pollution index Zc are characteristic for the Central and South-Eastern Districts, the lowest ones – for the Western and North-Western Districts. Analysis of Zc maps for 2007-2016 showed a decrease in soil pollution. In 2007, uncontaminated soils occupied 35.3% of the city’s area; slightly medium, and heavily polluted – 33%, 22.8% and 9.4% respectively. In 2016, this sequence was as follows: 65%, 22.7%, 11%, and 1.3%. This trend is associated with a decrease in industrial production in Moscow, the removal of harmful industries outside the city and the renovation of enterprises remaining in the capital, as well as with a reduction in emissions from vehicles. Changes in the location of man-made geochemical anomalies in soils reflect leveling in the pollution from vehicles due to the construction of new housing and the large-scale transformation of Moscow regions with a decrease in traffic in the center (Bityukova, Mozgunov, 2019).

How to cite: Kosheleva, N. and Tsykhman, A.: Pollution of Moscow soils with potentially toxic elements: analysis of long-term monitoring data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4207, https://doi.org/10.5194/egusphere-egu2020-4207, 2020.

Study of Zn and Cu accumulation and transformation in highly contaminated technogenically transformed soils near the sediment pond of a chemical plant using a combination of direct nondestructive physical methods, including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) based on synchrotron radiation. The object of the study was technogenic soils (Technosol) subjected to long-term anthropogenic load. The object of research was a territory of sludge collectors region of the Atamanskoe Lake natural basin, the city of Kamensk-Shakhtinskii, Southern Russia. The contents of Zn and Cu were determined by the X-ray fluorescence method. The EXAFS and XANES experimental data were obtained at the Structural Material Science Station at the 1.3b beamline of the Kurchatov Center of Synchrotron Radiation ''Kurchatov Institute''. Soil samples were analysed with the sequential extraction procedure recommended by BCR. This procedure can be described as follows: first step (exchangeable fraction), second step (reducible fraction) and third step (oxidisable fraction). The studied Technosols are characterized by exceeding of the lithosphere clark for Zn in hundreds of times (26 000-66 000 mg/kg) and for Cu in tens of times (376-577 mg/kg). It has been found that in the oxidisable fraction of Zn is coordinated by four O atoms and only two Zn atoms. The Zn-Zn distance is 3.36 Å, and there are two different short Zn-O bonds (1.95 and 2.04 Å). In the reducible and exchangeable fractions, the main peaks of the EXAFS Fourier transform are shifted to the region of large values, which indicates the possible presence of Zn-S bonds of 2.34 Å. The simulation results have shown a high content of ZnS in the reducible fraction; ZnS with an admixture of ZnSO₄ and ZnO dominates in the exchangeable fraction. The oxidisable fraction is characterized by a high content of ZnSO₄ with the addition of ZnO. The significant difference in the position of the absorption edge and the values of the main features of the spectrum with Cu–S and Cu–O bonds has made it possible to reliably diagnose these types of Cu environments in Technosol. Peaks of the EXAFS Fourier transforms of Cu spectra indicate the predominance of Cu–O bonds in the oxidisable fraction and Cu–S bonds in the reducible and exchangeable fractions. The results of fitting Cu spectra by a linear combination indicate that the spectra of the reducible fraction coincide with high accuracy with the spectra of Cu₂S. In the exchangeable fraction, the content of Cu₂S is also high, although there are CuSO₄ impurities. The oxidisable fraction is characterized by a high content of CuCO₃ and the presence of Cu₂S and CuSO₄ as impurities as trace amounts. Thus, sequential chemical selective fractionation and subsequent X-ray spectral diagnostics based on synchrotron radiation and molecular calculations have made it possible to identify and evaluate the Zn and Cu phases in Technosol.

The reported study was funded by RFBR, projects no. 19-34-60041 and 19-05-50097.

How to cite: Minkina, T., Nevidomskaya, D., Shuvaeva, V., Bauer, T., and Burachevskaya, M.: X-ray absorption analysis of Zn and Cu speciation in soils around the sediment ponds of chemical plants, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3848, https://doi.org/10.5194/egusphere-egu2020-3848, 2020.

Soil hydrophobicity was extensively investigated in the context of fire-induced, naturally-occurring and wastewater related hydrophobicity. Oil-induced soil hydrophobicity, however, received much less attention and was not yet investigated under regions characterized by hyper-arid climate. In this study, we investigate the hydrological effects and the persistence of oil-induced soil hydrophobicity in Evrona nature reserve located in the hyper-arid region of southern Israel. The Evrona nature reserve has experienced two oil spills that occurred in 1975 and 2014, providing a unique opportunity to study the hydrophobicity of oil-polluted soils over time. In this study, we 1) apply field monitoring to investigate how the severe hydrophobicity affects water flow in the polluted soils, and 2) conduct laboratory incubation experiments to assess the natural attenuation of hydrophobicity and its relation with the content and composition of hydrocarbons.

We set up two monitoring stations in two adjacent streams, of which one is polluted and the other is clean. In each section, an array of water content sensors was installed. Analyses of data measured during two years reveal that during rain and runoff events infiltration in the oil-contaminated soil was much lower relative to the clean soil. Furthermore, infiltration in the oil-contaminated stream showed highly preferential patterns, typical of hydrophobic soils. The reduced infiltration and the establishment of preferential flow paths may lead to negative consequences including increased runoff and erosion, reduction in the water available to native plants, and the generation of fast conduits for contaminant transport.

In the second part of the research, incubation experiments were conducted with contaminated soils from the 2014 and 1975 sites. Soils were treated with the addition of either water alone or different combinations of water, nutrients and surfactant. Treated soils were sampled periodically to assess soil hydrophobicity and hydrocarbon content. The results show a concomitant decrease in the hydrophobicity and hydrocarbon content in soils to which water or water and nutrient and/ or surfactants were added. The fastest hydrophobicity reduction was observed in soil to which both nutrients and surfactants were added, while when only water was added to 50% saturation, degradation and hydrophobicity reduction were very slow. Overall, during the one year and a half incubation, the total petroleum hydrocarbon of the treated soils decreased by 40% in the 2014 soil and by up to 80% in the 1975 soil. However, although hydrophobicity was reduced during incubation, the soils still remained severely hydrophobic. This suggests that considering the concentration of hydrocarbons as the sole criterion for the endpoint of soil remediation is not sufficient and the degree of soil hydrophobicity should be evaluated as well. 

How to cite: Rosenzweig, R., Li, Z., Gelman, F., Crouvi, O., Arye, G., and Ronen, Z.: Remediation and hydrological implications of oil-induced soil hydrophobicity in the Evrona nature reserve, Israel, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9195, https://doi.org/10.5194/egusphere-egu2020-9195, 2020.

A quantitative assessment of the potential soil erosion on arable land in the European part of Russia (EPR) was carried out. The total area of arable land of the EPR is about 650,000 km². The majority of the population of Russia lives here - about 95 million people. The level of generalization of work is regional and corresponds to a scale of 1: 500,000.

As a research method, mathematical modeling based on modified for Russia’s natural conditions USLE equation for calculating potential soil loss from erosion. Another leading method for assessing soil erosion and presenting results is GIS. A raster model of data presentation was used in the calculations, including a model of slope angles, slope lengths, soil erodibility, erosive rainfall potential, water reserves in snow, intra-annual redistribution of rainfall, and land use types.

New data have been obtained on the value of soil erosion losses during melt and storm runoff periods and total annual losses. An electronic map of soil erosion losses on arable lands of the European part of Russia has been compiled, which allows determining spatial features of soil erosion rates.

The average soil erosion losses, taking into account the soil-protective coefficients of agricultural crops for the study area, are 4.04 t / ha per year. In annual soil losses due to erosion, storm 3.78 prevails, soil loss from melt water is almost an order of magnitude less - t / ha 0.26. About half of the territory is located in conditions under which the soil loss does not exceed 0.5 t / ha per year.

The rate of potential soil erosion on arable land in the European part of Russia naturally decreases in the direction from the taiga-forest to the steppe landscape zone. The band of maximum potential soil erosion of the west-east sub-latitudinal strike is clearly distinguished, confined to the subzone of mixed and broad-leaved forests with very high plowing. A comparative analysis of our data and data obtained in the mid-1980s showed a reduction in soil loss from water erosion in all landscape zones. In addition, a comparative analysis of the data obtained by us and the data for the European Union was carried out, which showed that the soil losses on the EPR are slightly higher.

How to cite: Maltsev, K. and Yermolaev, O.: The soil loss by water erosion at the European part of Russia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10198, https://doi.org/10.5194/egusphere-egu2020-10198, 2020.

Historical ore mining and processing has considerably affected soil properties, causing the changes in local landscapes and soil enrichment in potentially toxic elements. Złoty Stok (formerly: Reichenstein), in SW Poland, was over many decades the largest European centre of arsenic mining and processing. Numerous mine and processing dumps have remained in that area. Waste material was in several sites intentionally spread on the land surface. Moreover, large floodplain areas were flooded by tailings released from disposal impoundments during stormy rains. The soils in all those sites contain high concentrations of arsenic, in extreme cases over 1%, while the permissible soil concentrations, considered environmentally safe, remain in the range 10-100 mg/kg, depending on land usage and soil properties. Remediation should be undertaken in all the sites with higher As concentrations, in order to reduce potential environmental risk and prevent As from entering the food chain. Because of relatively low As solubility and bioavailability, phytostabilization seems to be the best option of remediation. Grasses are particularly suitable for this purpose because of their quick growth, relatively large biomass, efficient coverage of the surface, and thick root systems. Major grass species are known as eliminators of heavy metals, highly resistant to their high concentrations. We examined the suitability of three grass species: Festuca rubra, Agrostis capillaris and Holcus lanatus for phytostabilization of As rich soils. As concentrations in their shoots were examined in the field and in a pot experiment. The latter was performed in order to examine the effects of various soil treatment, including fertilization, on plant growth and As uptake by plants. Soil treatment with manure increased strongly As extractability in soils but did not increase As uptake by grasses. The concentrations of As in plant shoots were in the pot experiment by manifold higher than those in the field. The maximum concentrations of As reported from the field for F. rubra, A. capillaris and H. lanatus were: 51, 9.3 and 62 mg/kg, while the corresponding maximum As concentrations from the pot experiments were: 390, 1020 and 570 mg/kg, respectively. Large differences between the field and pot data indicate that the populations growing in highly contaminated sites have probably developed a specific tolerance to soil As. Its possible mechanisms are discussed. One of the conclusions is that further pot experiments should be carried out with the seed material collected from enriched sites rather than with commercial cultivars. The data from the field indicate that all the three species of grass examined in this study are As excluders and relatively good candidates for phytostabilization of As-rich soils. However, the concentrations of As in the shoots of grasses growing in the most strongly enriched sites exceeded 4 mg/kg, the value set as a safe As content in fodder, posing therefore a risk to potential animal consumers.

How to cite: Karczewska, A., Szopka, K., Dradrach, A., and Gałka, B.: Accumulation of arsenic by various grass species growing in strongly contaminated sites affected by historical As mining and processing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11013, https://doi.org/10.5194/egusphere-egu2020-11013, 2020.

The emission and spread of global contaminants such as Pb, Cd, Hg, U and rare earth elements (REE) are of high global concern as they pose a serious health risk to humans and wildlife alike. Although the Arctic is a known hot-spot for deposition of globally transported organic and inorganic contaminants, Greenland is often viewed as pristine with little influence of local emission sources. This perception is, however, flawed as Greenland hosts numerous former, active and prospected mining activities, many of which have a profound adverse impact on the surrounding environment. Detailed monitoring before, during, and after mining activities is thus essential to evaluate the environmental health status of a mining area and to minimize the potential spread of mining derived contaminants.

Arthropods constitute the majority of the terrestrial Arctic species diversity, which facilitates sampling for environmental assessment. With documented abilities to accumulate contaminant metals (e.g. Cd, Ag, Hg), we show that spiders play a key role in bioaccumulation and biomagnification processes. Acting as both predator and prey, and by linking food webs in the aquatic to the terrestrial environment, spiders can enable a continued transfer of contaminants up the food chain. Moreover, and because arthropods are an important food source for migrating birds, there is a strong potential for a further geographical spread of contaminants. However, the extent to which contaminant bioaccumulation occurs in Arctic spiders, and their role in global contaminant cycles, remain unclear.

The aim of this project and presentation is to examine the use of wolf spiders (e.g. P. glacialis, P. furcifera and P. hyperborea) as biomonitors of metal and radiogenic contamination near Arctic mine sites. Particular focus will be given to the globally prioritized elements Pb and Hg (incl. isotopic signatures), as well as contaminants of local concern such as U (incl. decay series) and REEs. Further, we discuss the role of spiders in local- to global contaminant cycles by linking the contamination transfer through onsite food webs to location data from migrating birds (e.g. GPS-trackers). Combining contamination- and location-data will allow us to model movement of biota, and inherent mining derived contamination, to and from arctic ecosystems on an annual basis.

How to cite: Hansson, S. V., van Beest, F. M., Schmidt, N. M., Høye, T. T., and Søndergaard, J.: Wolf spiders as biomonitors of mining derived contamination in Arctic ecosystems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13413, https://doi.org/10.5194/egusphere-egu2020-13413, 2020.

The main work of soil reclamation in coal mine area is to recover the structure and function of soil, which is the key factor for the restoration of mine damaged ecosystem. The calculation of soil resilience is an index to measure the stability of ecosystem, which provides guidance for the sustainability of soil management. As the case of Heidaigou open pit mine in Mongolia, the soil restoration of waste dump in 1995, 2000, 2008 and 2015 is taken as the research objects. The field investigation and soil quality experiment data are used to compare and analyze between the reclamation soil and original soil. The soil resilience of waste dump of open pit mine is measured by principal component analysis and structural equation model. The results showed:  (1) The volume density of reclaimed soil was larger, and the soil particle size did not show obvious vertical layered distribution. The degradation of soil nutrients, the low level of soil fertility, the accumulation of soil alkaline hydrolysis nitrogen content and organic matter, and the utilization of plant roots to nutrients were low. The biodiversity and activity of soil decreased. (2) Quantitative evaluation of soil resilience was divided into four dimensions: soil structure stability, soil water retention capacity, soil fertilizer retention capacity, and soil biological activity. Soil clay particles, silt particles, median diameter, and sand particles contributed 81.609% to main component for soil structure stability. Surface water content, deep water content, bulk density, calcium carbonate contributed 82.379% to main component for soil water retention capacity. Soil organic, alkaline nitrogen, total nitrogen, pH, total potassium, total phosphorus, available phosphorus contributed 85.39% to main component for soil fertilizer retention capacity. Soil urease, alkaline phosphatase, invertase activity, microbial diversity Simpson index, richness Chao index, litter quality, pH contributed 87.373% to main component for soil biological activity. (3) Soil resilience was measured by four aspects: soil structure stability, soil water holding capacity, soil fertilizer holding capacity and soil biological activity. The average soil resilience value was 0.37, 0.33, 0.26, 0.18 in 1995, 2000, 2008, 2015, respectively. The average soil resilience was 0.75 in original soil. Soil biological activity had the positive impact on soil resilience, with an influence coefficient of 0.66. The water retention capacity and fertilizer retention capacity had coefficient of 0.44 and 0.37 on soil resilience.

How to cite: Hou, H. and Wang, C.: Measure soil resilience after reclamation of open pit dump in semi-arid area, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20768, https://doi.org/10.5194/egusphere-egu2020-20768, 2020.

The São Domingos mine is within the Iberian Pyrite Belt, one of the oldest mining districts in Europe, with one of the largest concentrations of polymetallic massive sulfide deposits. Mine waste heaps are considered extreme environments, since they possess high concentrations of potentially hazardous elements (PHE). When the presence of PHE is combined with adverse physical characteristics and low contents of organic matter and nutrients, the development of most plants is inhibited and the biodiversity of the area is drastically reduced. The transfer of chemical elements among the different solid phases contributes to control their behaviour, mobility and availability. Autochthonous plant species, such as Cistus salvifoliius L., which are well adapted to extreme environments and are able to grow naturally in degraded environments may contribute to minimize the negative chemical impacts and improve the landscape quality. However, the environmental rehabilitation processes associated to the development of these plants (phytostabilization) are very slow and the combined use of materials/wastes that improve some physico-chemical characteristics of the matrix is necessary. This work studied the effectiveness of the phytostabilization with C. salvifoliius of gossan mine wastes from the mine of São Domingos amended with organic/inorganic wastes. The amendments used were (g/kg of gossan): biomass ash (BA, 2.5), a mixture of organic residues (OR, 120) and a mixture of both (BA+OR).

The mine wastes have very acid pH, between 3.44 and 3.54, high total concentrations of PHE, such as As, Cu and Pb, and low concentrations of organic C and nutrients. The available fraction of Al, Ca, Fe, K, Mg and V in the mine wastes was, in general, less than 8% of their total concentration while for As, Cu, Mo, Pb and Zn it was less than 4.3% of the total. Nonetheless Mn availability lay between 21.2 and 24.8%.

The best vegetative development, that occurred without visible signs of toxicity, was obtained in the two treatments with organic wastes (OR and BA+OR). Independently of the treatment, this species does not behave as accumulator of PHE. High levels of Catalase activity were quantified in the soluble fraction of the roots from OR treatment and in the ionically bound fraction of roots from BA+OR treatment. As for Peroxidase, the activity quantified in the soluble fraction was slightly higher in roots than in shoots, while in the ionically bound fraction high values were measured both in shoots and roots.

The application of amendments, especially with organic matter (mixture or single application), together with the phytostabilization allowed the improvement of the plant-soil system namely at level of a better plant cover and improvement of several chemical characteristics of mine wastes (e.g. decrease of the majority of PHE in the available fraction, increase of fertility and water-holding capacity), leading to speed up the environmental rehabilitation.

How to cite: Carvalho, L. C., Santos, E., Saraiva, J. A., and Abreu, M. M.: Ability of Cistus salviifolius L. to phytostabilize gossan mine wastes amended with ash and organic residues, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18789, https://doi.org/10.5194/egusphere-egu2020-18789, 2020.

Soil microbial communities play vital roles in the biogeochemical processes, and they are sensitive to environmental pressure induced by environmental pollutants, including heavy metal or antibiotic contaminants. It is well known that exposure to heavy metals can increase microbial tolerance in contaminated soil. Recently it was also discovered that heavy metal exposure in agricultural soils could induce microbial tolerance to antibiotics, thus yielding human health concerns. To date, it remains unknown how wide-spread this co-tolerance is in the environment. The aim of this study was to determine the microbial tolerance under different heavy metal concentration levels, and to investigate whether increasing tolerance to metals will co-select for tolerance to antibiotic. We hypothesized that microbial tolerance to both heavy metals and antibiotics would increase with metal pollutant concentrations. The tolerance to pollutants was determined by the pollution induced community tolerance (PICT) approach and the concentration for 50% inhibition (IC₅₀) values.

To address our hypothesis, we collected soil samples from an ancient open cast land-mine in North Wales, UK, called Parys Mountain, known as the ‘Copper Kingdom’, where the soils cover a very wide span concentrations (c. 50 µg – 4000 µg g^-1 soil) of copper (Cu), lead (Pb) and zinc (Zn) alone or in combination. The soils were very acidic with pH range from 3.49 to 4.96, and soil organic matter contents very variable, from 5 to 46 %, yielding a wide range of water holding capacities, from 0.45 to 3.47 g water g^-1 dry soil. We determined basal soil respiration, SIR-biomass, microbial growth and community composition, and bacterial tolerance to Cu, Pb, Zn, tetracycline and vancomycin.

We found that bacterial growth rates significantly decreased with increasing available Cu (R² = 0.26) and decreasing pH (R² = 0.39), but did not show any regressions against with total metal concentrations, and total microbial biomass and respiration showed similar patterns. It was possible to reliably establish accurate dose-response relationships for bacterial tolerance to metals with average R² values of 0.96 for Cu, 0.93 for Pb, and 0.92 for Zn with logistic curve fits. Based on these, we estimated that bacterial tolerance to heavy metals varied substantially across the sites, with average log(IC₅₀) value was c. 4 log-unit Cu, 3.4 log-unit Pb, and 3.8 log-unit Zn. Metal tolerance was weakly linked to soil metal concentrations, as shown by limited linear relationship built between tolerance and soil concentrations (R²= 0.25, 0.44, 0.20 for Cu, Pb and Zn, respectively). The substantial variance in heavy metal tolerance among the sampled mining soils provided a high power to assess if metal tolerance could induce tolerance also to antibiotics. To assess this, we established dose response relationships between bacterial growth and a common and widely used antibiotic (tetracycline) as well as an antibiotic held in reserve for human therapy (vancomycin). The toxicity estimates are still awaiting analyses, but we hypothesize a strong link between bacterial tolerance to tetracycline and that for Cu, Zn, and Pb, while a weaker or non-existent pattern is expected for vancomycin, due to its limited environmental presence.

How to cite: Zhong, Q., Paredes, C. C., and Rousk, J.: Can heavy metal pollution induce bacterial tolerance to antibiotics in soils from ancient land-mines? , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6019, https://doi.org/10.5194/egusphere-egu2020-6019, 2020.

Cs-137 distribution was studied in the regular grid and in landscape cross-sections characterizing the ELGS system (top-slope-closing depression) in the “Vyshkov-2” test site located in the Chernobyl abandoned zone, the Bryansk region, Russia. The test site (70×100 m) located on the Iput’ river terrace in a pine forest formed on sod-podzolic soils is characterized by a pronounced elevation gradient (ca 4.5 m). In 1986 the level of ¹³⁷Cs contamination of the area varied from 1480 kBq/m² to 1850 kBq/m². The distribution of ¹³⁷Cs was studied in the topsoil, soil, moss and litter cover in a grid manner with a step of 10 m and along cross-sections with 1 m step. To assess the influence of water regime on radiocaesium migration moisture content was also determined in the studied objects. The data showed that the major part of ¹³⁷Cs is now fixed in the soil layer 2-10 cm thick while the highest activity of radiocaesium is found at a depth of 2-8 cm that can be explained mainly by the burial of the initially contaminated layer under the annual leaf fall. In the ELGS system the content of ¹³⁷Cs in the top soil layer (0-2 cm) determined in laboratory conditions by Canberra gamma-spectrometer with HPGe detector correlated with the surface Cs-137 activity measured by field gamma-spectrometer Violinist III (r=0.643, n=15). Cs-137 activity in the green part of moss samples correlated with the radionuclide activity in soil layer samples 4-6 cm deep (r=0.627, n=15). In the moss samples the highest correlation was observed between the green and rhizoid moss parts (r_0.01=0.718, n=60, along cross-sections), (r_0.05=0.858, n=20, in regular grid). Correlation between radiocesium activity of the green part of mosses and the underlain litter samples was lower, but also significant (r_0.01=0.617, n=60, along cross-sections), (r_0.05=0.481, n=20, in regular grid). Cs-137 activity in the rhizoid part of moss and in litter were also positively linked, but to a lower degree (r_0.01=0.402, n=60). Studies performed in 2015-2019 confirmed our earlier finding that radiocaesium had not moved in unidirectional manner down the slope to the closing depression, but formed a more complex polycentric structure in ELGS.

The study was financially supported by the Russian Foundation for Basic Research (grant # 19-05-00816).

How to cite: Dolgushin, D., Korobova, E., Baranchukov, V., and Dogadkin, N.: Detailed study of 137Cs distribution in soil-litter-moss cover within the undisturbed woodland test site in the Chernobyl abandoned zone, Russia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-339, https://doi.org/10.5194/egusphere-egu2020-339, 2020.

The collapse of a tailings dam of a Pb-Zn mine, caused by a storm in 1978, resulted in severe heavy metals contamination in the valley downstream the mine, located in the Guangxi Province, southwest of China. The metals still pose a risk to the adjacent fragile karst environment. Especially, the potential for leaching of the heavy metals to the adjacent environment is of concern due to the high average annual precipitation of >1500 mm in the subtropical climate. Previous studies have classified areas of the valley as slightly (SP), moderately (MP) or heavily polluted (HP) based on heavy metals content (Pb, Cd, As, Cu, Zn) of the upper 20 cm of the soils. We analysed soil and sediment profiles up to 2 m deep, obtained in areas of the three pollutions levels, for basic chemical and physical parameters including pH, total organic carbon (TOC), soil moisture, particle size, total metals concentrations (Pb, Zn, Cd, and Cu), and δ¹⁸O and δ²H of soil moisture. Further, we measured the δ³⁴S of soil extractable sulphate, and the content of chromium-reducible sulphur (CRS) and soluble sulphates (SS), to investigate the link between sulphur cycling and heavy metals mobilization. Today, four decades after the dam collapse, heavy metal concentrations are still highly elevated in the valley. In the HP profile concentrations of Pb, Cd, Cu and Zn range between 800–8120, 8–132, 156–616, and 2647–12250 mg/kg, respectively, between surface and 2 m depth. Concentrations of CRS in the HP profile of 287–5530 mg/kg were observed, while no CRS could be extracted from the SP and MP soil profiles. The δ³⁴S-SO₄^2- of the HP profile (0.4‰–16.0‰) matches values previously measured in the original tailing. The matching δ³⁴S-SO₄^2- and elevated CRS values of the HP profile indicate that the valley contains thick deposits (up to at least a 2 meters) of resettled tailings sediments of the original upstream tailings dam. However, these sediments are clayey, with >50%wt being <0.002 mm in particle size, allowing only a slow advective water and solute movement to or from (leaching) the sediment. A currently low, yet possibly significant(!), heavy metals leaching is further indicated by the only slightly acidic pH (6-6.5) which indicate a lack of oxygen intrusion into the sediments and reaction with the CRS content. Also, the HP profile had soluble sulphate concentrations of 532–1156 mg S/kg which were reasonably comparable to the values measured in the less polluted areas, implying a history without large amounts of CRS oxidation. Further, Pb and Cu concentration in the HP profile shows a continuous (high) distribution vs. depth which also suggests a history without extremely low pH. Finally, deuterium-excess values can be interpreted as showing diffusive, rather than advective, water and solute movement. While, accordingly, the heavy metals currently appear relatively well stabilized towards leaching, any management that increases oxygen intrusion or water exchange will impose a high risk of immediate and severe environmental pollution to the adjacent aqueous environment.

How to cite: Qin, W., Han, D., Song, X., and Jessen, S.: Controls on mobility of heavy metals of mine tailings in a karst area as shown by multi-stable isotopes tracing: δ18O/δ2H in soil water and δ34S of soil soluble SO42-, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21762, https://doi.org/10.5194/egusphere-egu2020-21762, 2020.

Although 40% of Hungary's territory is very sensitive to deflation, few studies have been conducted on wind-eroded sediment as an environmental pathway for pesticide transport.

Three experiment were conducted on loam soil and an other in sandy soil near Szeged (Hungarian Great Plain) in 2017, 2018, 2019, to examine wind-eroded sediment as a transport mechanism for two surface-applied pesticides [chlorpyrifos and pendimethalin].

For the experiments we used a portable 12 m long wind tunnel and a Wet Active Sediment Trap (WAST). WAST is a horizontal, isokinetic active wet trap that is patterned at different heights to collect the suspended soil fractions. Trap inlets are 5-10 cm, 20-25 cm, 50-55 cm high. Rolling soil samples (sediments) were also collected in a recessed tray at the end of the wind tunnel with a clean brush.

Before the experiment, a part of the sample area was treated with chlorpyrifos (2l/ha) and pendimethalin (5l/ha). A control area was also selected. Samples were taken before and after the wind event at 3 different places in the wind tunnel.

In the laboratory we analyzed the topsoil samples (pH (H₂O), CaCO₃ (%), Arany yarn test, OM %, total salt content (%), humidity (%), pesticide contents) and the collected sediments (chlorpyrifos, pendimethalin concentrations) according to hungarian standard procedures.

We calculated the enrichment ratios (ER) of concentrations in the rolling and suspended samples.

Our measurements showed that the enrichment of chlorpyrifos and pendimethalin can be clearly indicated in the sediments. The mean value of chlorpyrifos ER in 2017 is 3,4. In 2018 the mean value of chlorpyrifos ER is 2,9 and of pendimethalin ER is 13,7. Pendimethalin ER is much higher in the rolled fraction than chlorpyrifos. Measurements of 2019 showed us that the analyzed pesticides were enriched in the rolling soil fraction. There were no pesticides enrichment in the suspended fraction.

The research was funded by the ‘Thematic Network for the Sustainable Use of Resources – RING2017’ project (program code: EFOP-3.6.2-16-201700010) and by the support of OTKA 1K 116981, "In situ wind channel experimentation based on in situ wind channel experiments on different soil types, on site and off site effects" and supported by the ÚNKP-19-3 New National Excellence Program of the Ministry for Innovation and Technology”.

How to cite: Csányi, K., Barta, K., Szatmári, J., and Farsang, A.: Wind Erosion Contribution to Pesticide Transport, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22201, https://doi.org/10.5194/egusphere-egu2020-22201, 2020.

An urban world population of 0.75 billion in 1950 and expected 6 billion in 2050 shows the tremendous potential growth of urban areas. The urban soil fulfills the role of the reactor for the physical, chemical and biological transformations of matter but also covers such functions as reduction of air pollution, regulation of climate elements in cities, source of biodiversity and formation of areas for ornamental and recreation purposes. As a usual part of urban ecosystems, urban soils in general have high concentrations of trace elements derive from human activities. The objectives of this work were (1) to quantify the concentrations and establish background levels of Ba, Co, Cr, Cu, Mn, Pb, Ni, V and Zn in soils of Coronel city; (2) to assess the degree of pollution and identify local sources of pollution and (3) to assess the health risks of TE in soils of Coronel city. From Coronel city were collected 129 samples from 43 sites located in schoolyards and playground areas. At each sampling point were taken three samples: topsoil sample (TS) (0-10 cm), subsoil sample (SS) (10-20 cm) and deep soil sample (DS) (150 cm). Multivariate statistical analysis and depth ratios were used to distinguish the source. Ecological indices were implemented to evaluate the degree of contamination. The median and (range) of the trace elements (TE) in TS were Ba 38 mg kg^-1 (12-147 mg kg^-1), 38 mg kg^-1; Co 4-40 mg kg^-1; 15 mg kg^-1; Cr 10-35 mg kg^-1, 18 mg kg^-1; Cu 12-70 mg kg^-1, 22 mg kg^-1; Mn 167-950 mg kg^-1, 536 mg kg^-1; Ni 11-115 mg kg^-1, 35.5 mg kg^-1; Pb 1.5-115 mg kg^-1, 6 mg kg^-1; V 52-528 mg kg^-1, 94 mg kg^-1; Zn 42-373 mg kg^-1, 65 mg kg^-1. Depth ratios and multivariate statistical analysis suggested that Co, Ni and Mn have principal contribution of geogenic sources and Ba, Cr, Cu, Pb, V and Zn anthropogenic sources. The upper limit of background values estimated with median absolute deviation (MAD) method and DS samples were Ba 30 mg kg^-1,  Co 24 mg kg^-1,  Cr 22 mg kg^-1,  Cu 24 mg kg^-1,  Mn 662 mg kg^-1,  Ni 66 mg kg^-1,  Pb 1.5 mg kg^-1,  V 108 mg kg^-1,  and Zn 52 mg kg^-1. Contamination factor showed that some soil sample were categorized as considerable contamination to very high contamination for Pb, Zn and V. Both Hazard index and cancer risk indicated no adverse health effects.

Keywords: Heavy metals, urban soils, ecological indices, health risk assessment

How to cite: Tume, P., Acevedoa, V., Roca, N., and Bech, J.: Trace metals concentrations in schoolyard and playground soils in Coronel city, Chile, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3887, https://doi.org/10.5194/egusphere-egu2020-3887, 2020.

Mediterranean coastal areas have been cultivated for long time. Wetlands areas situated near to the coast have been drainaged by using drainage channels. Heavy metals can be transferred from soils to the channels under agricultural management practices, especially under flood and furrow irrigation (the most important in the area studied). Anthropogenic inputs, including excessive use of agrochemicals and manure, in agricultural soils contribute to an increase of the content of some toxic heavy metals [1].

The agricultural area situated in the South of the province of Alicante has an important drainage system (avoiding to be a coastal wetland), which more than a thousand kilometers that allow the cultivation on calcareous soils (mainly Fluvisols). However, land uses have been changing and an important transformation of rural areas to residential areas have been occurred in the recent decades.

Under this situation, the presence of Cd, Cr and Ni in drainaged waters derived from infiltration from agricultural soils, and runoff from some urban areas, have been checked in the main drainage system (13 drainage channels) in order to detect possible influences of soil management in metal pollution. Water samples were taking along the channels in three to ten points of each channel, depending on the length, and metals were analyzed following standard methods [2]. At the same time, the land cover has been analyzed by using the last data from National Aerial Orthophotography Plan (available from the National Center of Geographical Information, Spain).

The most important result obtained was that the presence of Cd in the waters was under the limit of detection of 0.1 μg/L. This result reflected the absence of pollution sources of this metal from soils to these drainage channels.

Moreover, in the case of Cr, the values obtained were even below the reference values ​​for drinking water [3]. However, the major concentrations of this metal were between 6 to μg/L in only 4 channels. Ni, whose concentrations were lower than those for Cr, has values under 7 μg/L. Heavy metal pollution, at least in the elements analyzed, does not seem to be a serious problem in terms of the quality of these waters.

Although many land cover changes have occurred, most of the soils are dedicated to agriculture. On the other hand, no clear effects related to the proximity of urban areas to the drainage channels have been observed.

Keywords

Heavy metals; irrigation; land cover changes, pollution, wetlands.

References

[1] Navarro-Pedreño, J.; Almendro-Candel, M.B.; Gómez, I.; Jordan, MM; Bech, J.; Zorpas, A.A. (2018). Trace metal content and availability of essential metals in agricultural soils of Alicante (Spain). Sustainability 10, 4534.

 [2] APHA, AWWA, WEF (2012). Standard Methods for the examination of water and wastewater. Ed. American Public Health Association, Washington.

[3] Real Decreto 314/2016, de 29 de julio, por el que se modifican el Real Decreto 140/2003, de 7 de febrero, por el que se establecen los criterios sanitarios de la calidad del agua de consumo humano.

How to cite: Navarro-Pedreño, J., Almendro-Candel, M. B., Meléndez-Pastor, I., Gómez-Lucas, I., Jordán, M. M., García-Sánchez, E., Bech, J., and Zorpas, A. A.: Cd, Cr and Ni in drainage water from agricultural soils. Case study of South Alicante., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2838, https://doi.org/10.5194/egusphere-egu2020-2838, 2020.

When dealing with restoration and remediation projects of zones contaminated by waste and activities derived from mining operations, all the aspects that affect the neighbouring areas dedicated to the cultivation of vegetables are especially relevant, and should be carefully considered. According to previous studies carried out, the areas of mining influence affect to a very different extent the bordering areas depending not only of the characteristics of the soil but also of the type of mining activity that was developed, and so of the primary mineralogy involved, and even of the particular type of vegetable that is being cultivated. The diversity and complexity of these factors suggest the convenient of studying the process by clarifying the mechanisms of transfer of potentially toxic elements from the soil to the biotic environment, with the soil-plant-biotic chain sequence.

In this work an experimental study was carried out with this purpose making use of experiments carried out at the greenhouse scale in order to find a model that could clarify the processes that could take place in restored soils.

Construction and demolition residues (CDRs) as well as other residues containing high concentrations in limestone filler were used to prepare technosols, and the transfer factors (TF) and bioconcentration factors (BCF) of potentially toxic elements were measured for the selected plant species (chard and broccoli). In this way, in addition to the soil remediation, benefit can be obtained of the re-valorization of such type of  easily available, low cost residues. For the realization of the tests in the greenhouse, four technosols were prepared and experiments were planned in duplicate, which constituted eight experimental units, each one containing 21 large pots disposed in such a way that leachates were poured in the same storing tank.  

The technosols were prepared as follows:

• Vegetable soil or reference soil. (T1)
• Contaminated soil: 50% reference soil + 50% mine residue (T2).
• Amended Land 1: 75% contaminated soil + 25% CDR (T3).
• Amended soil 2: 75% contaminated soil + 25% Limestone filler (T4).

A statistical study was carried out to evaluate the relationships between the levels of potentially toxic elements (Pb and Cd) found in rhizospheres and root contents and the levels present in the technosols prepared. Conclusions could be obtained as regards  the mobility of  these elements, the characteristics of the technosols and the type of cultivation. The data allows a model to be outlined that could be translated at a higher scale for an effective remediation of large zones.

How to cite: Pérez-Sirvent, C., Martinez-Sanchez, M. J., Martinez-Lopez, S., Agudo, I., and Bech, J.: Transfer of heavy metals to plants in technosols remediated with calcareous residues., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6154, https://doi.org/10.5194/egusphere-egu2020-6154, 2020.

A promising planning for recovery and closure of mining tailings, from both active and abandoned mines, must include environmental and socioeconomic approaches. Buenaventura group and La Zanja mine are evaluating, in different closure systems of tailings composed of mine wastes rich-in sulfides, the integrated rehabilitation of the ecosystem (mine wastes, percolated leachates, runoff water and plants cover) and its recovery to other secure land uses which promote the regional socio-economic valorisation. In adjacent areas to La Zanja mine (Cajamarca, Peru), the milk production is the main economic activity although with low profitability. Therefore, herbaceous and shrubs intake by domestic animals could be one important food chain route for human exposure to toxic elements. Although it is essential the evaluation of the potential animal feed risk, until what is known these studies are not usual in mine closure planning.

This work aims to evaluate, at long term, the chemical and microbiological characteristics of the soil, and development and environmental potential risk of the herbaceous strata growing in mine tailings closed with two conventional closure systems and innovative system with a Technosol designed specifically for environmental problems of the mining tailing. The studied conventional systems are characterized by superficial coverage with local soil or local soil under materials with low permeability. Before planting native plant species and different fast-growing herbaceous, amendments were applied to the soil, such as lime and/or chicken manure. In other mine tailing with similar chemical and mineralogical characteristics was applied a superficial layer of a designed Technosol with andic, eutrophic and reductor properties. An adjacent area without influence of mining activity was used as control.

Composite samples of soils as well as herbaceous plants and dominant shrub growing on these soils were collected. Soil characteristics (pH, fertility, overall activity and biomass of microbial community) and multielemental concentration in soils (pseudototal and available fractions) and plants were determined. The accumulation behaviour of potentially hazardous elements in shoots was studied as well as their relation with the chemical soil characteristics.

The chemical and biological quality of the soils depended on closure system. Soils from conventional system presented significant degradation at chemical and biological level and smaller plant development, compared to system with Technosol. The chemical characteristics of the Tecnosol still remained being, in many cases, better than those in control soil.

In conventional systems, the alteration of the chemical characteristics of the soils and/or presence of the layer of low permeability material limited the plant development biomass production contributing to a higher risk of erosion. Herbaceous species growing on the soils from all studied closure systems of mine tailings do not seem to represent an environmental risk for domestic animals that exist in the areas adjacent.

This study is included in a strategy environmental management and sustainable development for the recovery of non-productive areas for other land uses.

Financial support grated by: InnóvatePerú–FINCyT 2 (PITEI-4-P-015-091-16) to Compañía de Minas Buenaventura and Minera La Zanja; Fundação para a Ciência e Tecnologia to LEAF (UID/AGR/04129/2013).

How to cite: Santos, E., Cornejo, M., Arán, D., and Gallardo, A.: Risk assessment of the land recovery to pastures on sulfide tailings closed with different systems: Conventional Vs Technosol, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12527, https://doi.org/10.5194/egusphere-egu2020-12527, 2020.

Sorption parameters of natural zeolite-containing tripolite from the Khotynetsky deposit (Russia, Oryol region) were studied in a series of experiments to evaluate possibility of its usage as a geochemical barrier for teсhnogenic Ni²⁺ and Zn²⁺ contaminating soils and ground waters. 
Firstly, the tripolite total ion-exchange capacity was established by its saturation with ammonium ion and evaluating its content in the initial and ammonium forms with the help of X-ray fluorescence method. Secondly, the kinetic characteristics, namely the time necessary to reach the equilibrium state of the rock-water system containing Ni²⁺ and Zn²⁺ ions were determined in batch experiments using the method of "limited volume". The latter experiment was conducted using 0.5 g tripolite with 250 ml model solutions simulating natural river water (0.003 н CaCl₂) and filtration water from solid domestic waste landfill (0.06 н CaCl₂) and containing  2 mg/l Ni²⁺ and  Zn²⁺. The time of contact between the sorbent and the model solution varied from 2 hours to 21 days. Thirdly, basing on reference data on the real content of heavy metals in the filtrates of various landfills, an experiment on determination of the tripolite equilibrium exchange (and adsorption) capacity was carried out. The prepared model solutions in the latter experiment contained 2, 5, 7 and 10 mg/l of Ni²⁺ and Zn²⁺. The amount of Ni²⁺ and Zn²⁺  in solutions was determined by the ICP-AES.
According to the obtained results, the total ion-exchange capacity of the natural tripolite equaled to 1.18 mg-eq/g. The sorption isotherms based on kinetic experiments showed that equilibrium in the studied rock-solution system took place after 200 to 500 hours of interaction. Despite natural scattering of experimental points in the range of the used Ni²⁺ and Zn²⁺ concentrations in the third experiment which lasted 21 days, the sorption of the studied ions by the natural tripolite can be approximated by a linear isotherm, zinc being sorbed much better than nickel. The average values of distribution coefficients (Kd) obtained for 0.003 n CaCl₂ aquatic solution equaled to 2.7*103 ml/g for Ni²⁺ and 6.7*103 ml/g for Zn²⁺.
Therefore, natural tripolite of the Khotinetsky deposit may well be used as a natural geochemical barrier for extraction of technogenic Ni²⁺ and Zn²⁺ from natural waters draining landfills and contaminated by these ions.

How to cite: Kolmykova, L., Nikashina, V., and Korobova, E.: An experimental study of sorption properties of natural zeolite-containing rocks and their ability for purification of aquatic solutions contaminated with Ni and Zn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2224, https://doi.org/10.5194/egusphere-egu2020-2224, 2020.

Soil is one of the key elements for all terrestric ecosystems. The ability of soils to adsorb metal ions from aqueous solution is of special interest and has consequences for agricultural issues as remediation of polluted soils. The aim of this work was to study the mechanisms of copper and zinc adsorption by meadow soil in the Rostov region (Russia). To study the ion-exchange adsorption of the Cu²⁺ and Zn²⁺ cations, the soil in the natural ionic form was disaggregated using a pestle with a rubber head and sieved through a 1mm sieve. The soil samples were treated with solutions of Cu²⁺ and Zn²⁺ nitrates at the separate presence of metals. The concentrations of the initial solutions were 0.05, 0.08, 0.1, 0.3, 0.5, 0.8 and 1.0 mM L^–1. The soil:solution ratio was 1:10. The suspensions were shaken for 1 h, left to stand for 24 h, and then filtered. The contents of the metals in the filtrates were determined by atomic absorption spectrometry. The contents of adsorbed cations were calculated from the difference between the metal concentrations in the initial and equilibrium solutions.  The isotherm of Cu²⁺ and Zn²⁺ adsorption by meadow soil from nitrate solutions is described by the Langmuir equation:

C_ad = C_∞K_lC_{e /} (1 + K_lC_e),                        (1)

where Cad is the amount of adsorbed cations, C_∞ is the maximum adsorption, mM kg^–1, C_e is the concentration of the metal in the equilibrium solution, mM L^–1 and K_l is the Langmuir constant, L mM^–1.

According to the binding strength (constant value К_l) to the meadow soil, the studied cations form the series Cu²⁺ (103.7±6.3) >> Zn²⁺ (3.9±0.4). The specific interaction with the soil exchangeable complex could be more typical for the adsorption of Cu²⁺ by the soil than for the adsorption of Zn²⁺. The obtained regularity also coincides with the order of the change in the electronegativity of the metals. The higher the electronegativity of a metal, the stronger its interaction with the surface of the soil particles, which results in the formation of stronger bonds with the surface functional groups. The values of the maximum adsorption (С_∞) for Cu²⁺ and Zn²⁺ decrease in the same order as the constants, but not so significantly: Cu²⁺ (13.2±0.4) > Zn²⁺ (3.9±0.4). Thus, the maximum adsorption, an extensive characteristic of the adsorption, is a less sensitive parameter than the equilibrium constant of adsorption K_l, an intensive characteristic of the process.

The reported study was funded by RFBR, project number 19-34-60041.

How to cite: Bauer, T., Minkina, T., and Pinskii, D.: The adsorption mechanisms of heavy metal ions by meadow soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-471, https://doi.org/10.5194/egusphere-egu2020-471, 2020.

Chemical pollution of the environment is one of the most serious problems for mankind in the modern time. The main sources of pollutants entering the environment are atmospheric emissions of industrial enterprises, ore dumps and wastes released by the chemical industry. However, regardless of the source of the pollutants, the main function in reducing environmental risk is performed by the soil. With the increasing anthropogenic load on natural landscapes and agricultural lands, reliable data on the toxicity of heavy metals (HM) as well as the mechanisms of their entry into the plants are needed to carry out environmental monitoring and quality control of grown products.

The accumulation and transformation of Ni, Mn, Zn, Cu, Cr, Cd, and Pb in soils of steppe zone of southern Russia were studied under different sources of pollution: aerotechnogenic emissions by Novocherkassk power station and industrial effluents of the chemical plant near Kamensk-Shakhtinskii city. The author’s method for determining the HM compounds composition in the soil (Minkina et al., 2008) was used to assess the ecological situation of the impacted territory. It was found that the total content of HM in the soils of the impacted territories exceeded Clarke value, especially for Zn (up to 796 times).

The patterns of accumulation and distribution of Ni, Mn, Zn, Cu, Cr, Cd, and Pb were determined for the most common species of wild-growing and agricultural herbaceous plants of the Poaceae (Triticum aestivum, Hordeum sativum, Poa pratensis L.), and Asteraceae (Ambrosia artemisiifolia, Achillea nobilis, Tanacetum vulgare) that grew in the impacted territory. Agricultural and wild herbaceous plants growing 1.5–2.2 km from the power station are polluted with Pb, Zn, Ni and Cd.

It was shown that even in conditions of extreme soil pollution by industrial effluents, the root system of the plants successfully performed its protective function: the HM content in roots significantly exceeded it in above-ground part. At the same time, the pollutants concentration ratio in the above-ground part and in the roots was higher under aerotechnogenic pollution due to the additional receipt of the HM through the surface of the leaves. The dependence between HM accumulation and distribution in plants and the content of mobile metal compounds in the soil was established (correlation coefficient=0.79).

The extreme HM contamination effect on the anatomical and morphological characteristics and ultrastructure of the cultivated and wild plants was studied by transmission electron microscopy. The differences in adaptation of the plants to the effects of a stressful environmental factor were manifested not only in the external structure but also at the anatomical and intracellular levels of organization. In the samples contaminated with HM, parenchyma cell vacuoles contained electron-dense inclusions grouped in the center of the vacuole which were probably the deposits of metal compounds. Cultivated herbaceous plants of Poaceae family were found to be more susceptible to anthropogenic pollution with HMs compared to the wild plants of the same family.

Research was supported by the Grant of the President of the Russian Federation, project no. MK-2818.2019.5, RFBR, project no. 19-29-05265.

How to cite: Chaplygin, V., Mandzhieva, S., Minkina, T., Chernikova, N., Fedorenko, A., Barahov, A., and Lobzenko, I.: The effect of different level and type of pollution on the heavy metals accumulation and distribution in soil-plant system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-684, https://doi.org/10.5194/egusphere-egu2020-684, 2020.

The level of contamination with the natural (K-40, Th-232, Ra-226) and induced (Cs-137) radioactive nuclides of the following forest soils(pine- trees, fir-trees, birch-trees) and of the long fallow ecological systems at the polluted (southern part) and not polluted (northern part) territories of Kaluga region of the Russian Federation, was evaluated in 2017. The analysis showed that the specific activity of the natural radioactive nuclides Ra-226 and Th-232 is low and it changes insignificantly in the soils' profile of the studied ecological systems. Higher levels of K-40 are registered, reaching the maximum in the long fallow soils, which arises from a heavier granulometric composition of the differences that were formed here. In general the density of soil contamination with the natural radioactive nuclides in various ecological systems varies: 3,14-11,70 for Ra-226, 0,33-3,22 for Th-232 and 3,52-94,19 kBq/m2 for K-40, which corresponds to the background indexes  and complies with the regional lithological features of the territory. The density of the soils contamination with Cs-137 varies from 60.8 to 273,8 kBq/m2 at the polluted territories(it does not exceed 3 kBq/m2 at the background territories). Among the studied ecological systems the forest ones (especially coniferous) are the most contaminated with Cs-137, the long fallow ecological systems are the least contaminated with Cs-137. In comparison with the initial period starting with the precipitation in 1986, the density of soils' contamination with Cs-137 has presently decreased by more than 3 times in average. However this index still significantly exceeds the admissible level of 37kBq/m2. Cs-137contributes most significantly into the summary specific activity of the soils and gives the power of the  equivalent absorbed dose for the  ecological systems of the polluted territories. K-40 provides this effect for the background territories.

How to cite: Kononets, O., Shcheglov, A., and Tsvetnova, O.: Natural and induced radioactive nuclides in the soils of forest and long fallow lands of the background and polluted territories of Kaluga region of the Russian Federation. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-721, https://doi.org/10.5194/egusphere-egu2020-721, 2020.

Having drinking water is one of the sustainable development goals (SDG no. 6) that is not always easy to ensure, especially in countries like Spain or arid regions marked by water deficit. The reuse of treated water should be considered when planning water resources, but it is necessary to conduct experiments to verify that this effectiveness is applicable to real situations. Our field trial was carried out in several study areas distributed in agricultural parcels of SE Spain. Three olive grove and vineyard plantations were monitored for 3 years. Two irrigation water types were considered: freshwater from conventional wells (controls) and treated wastewater (TW). The treated wastewater came from three different wastewater treatment plants (WWTP) that employ a biological secondary treatment without disinfection and different numbers of Inhabitants Equivalent (IE) as a measure of pollutant load. They were located in Valdeganga (3,000 IE), Fuenteálamo (5,600 IE) and Ontur (1,500 IE). All the study plots were watered by drip irrigation using 16 mm-diameter polyethylene pipelines.

Several soil and water parameters were analysed to determine the main differences among them. Increasing of soil salinity is a real risk after irrigating with wastewater as is reflected in higher electrical conductivity values. However, this fact was compensated by the greater contribution of organic matter and nutrients, which allowed crops to adequately develop. Moreover, no microbiological, metal content, toxicity or organic compounds in the studied water samples were detected and reclaimed municipal wastewater was comparable in quality to the conventional sources at all the demonstration sites. Hence adopting this water type for irrigation for grapes and olives could help save primary water resources. The future of water resources management policies involves sustainable wastewater reuse within a circular economy frame because this is the only way to guarantee everyone solidarity access to water.

Fundings provided by the ERA-NET WaterWorks2014 Cofunded Call. This ERA-NET is an integral part of the 2015 Joint Activities developed by the Water Challenges for a Changing World Joint Programme Initiative (Water JPI).

How to cite: Mañas Ramírez, P., De las Heras Ibañez, J., and Peña Molina, E.: Reclaimed wastewater to irrigate olive groves and vineyards: effects on soil properties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3424, https://doi.org/10.5194/egusphere-egu2020-3424, 2020.

Increased atmospheric CO₂ concentration will have an significant impact on the nitrogen cycle of terrestrial ecosystems. The elevation of atmospheric CO₂ has become an inevitable trend, and nitrogen is the most important factor affecting plant growth. But it is rare to explore the effect of CO₂ on nitrogen cycle by measuring the value of δ¹⁵N. The δ¹⁵N value as a comprehensive indicator of the nitrogen cycle of the ecosystem, which can not only clarify the migration and transformation of nitrogen, but also effectively indicate the nitrogen limit and nitrogen open level of the ecosystem. Our experiment selected alfalfa (C3 plant) as the research object, then investigated the response of nitrate nitrogen, ammonia nitrogen and absorbable nitrogen to the elevated CO₂ concentration in soil and alfalfa leaves under ambient and elevated atmospheric CO₂ (500 and 700ppm) in open top chambers. The ¹⁵N isotope value was determined by bacterial denitrification , and ¹⁵N-gas chromatography (GC-MS) were applied to further analyze the effect of elevated CO₂ concentration on nitrogen cycling in soil and plant leaves. The increase of CO₂ concentration led to the decline of various inorganic nitrogen levels in soil, and the δ¹⁵N in the soil also showed a certain downward trend, but always maintained a positive value. The nitrogen level and δ¹⁵N values in alfalfa leaves did not change significantly, showing a small increase. It indicates that there are different degrees of nitrogen loss in the leaves under the influence of different concentrations of CO₂. These results are closely related to the fractional distillation of nitrogen isotopes caused by microorganisms in the process of nitrogen morphologic transformation. We briefly reviewed the changes of nitrogen content in soil and plant leaves under elevated CO₂, providing new insights into the nitrogen cycle of soils and plants under high CO₂ concentrations. It also provides a scientific basis for the protection of soil and plants under the greenhouse effect.

How to cite: Zong, Y., Hu, J., Zhuang, Z., Li, Y., and Liu, W.: Effects of elevated CO2 on nitrogen cycling in soil and alfalfa leaves, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5139, https://doi.org/10.5194/egusphere-egu2020-5139, 2020.

With the increasing population growth rate, and in order to attain the goals set by the 2030 Agenda for Sustainable Development, it is necessary to find solutions that can ensure food security and food safety. Population growth implies not only increasing food demand, but also land use for housing, which ultimately results in the need to claim more land. However, with only 30% land available in the world, it is crucial to find strategies to answer the demands for the near future. A potential strategy could be the reclaiming/recovery of marginal lands, such as salt and drought prone lands, or even abandoned mining areas, that are not suitable for farming. The latter is still a controversial approach, because of the knowledge void, as to determining pollution level, environmental and health risk assessment protocols, contaminated sites identification, all factors that can diminish the success of sustainably recover abandoned mining areas. Mining activities result in land degradation, environmental contamination and thus ecosystem disruption. Soils/wastes from mining areas are rich in potentially hazardous elements (PHE) that cannot be degraded, thus there has been recent efforts to create sustainable ecotechnologies that could rehabilitate these areas, creating conditions for agriculture activities while assuring food safety. Phytostabilization is a prospective rehabilitation strategy that uses adapted/tolerant plants towards PHE immobilization in the rhizosphere and most especially with low PHE translocation factors from soil/roots to shoots. Allying with this, one can improve soil properties (e.g. fertility, water-holding capacity, structure) to promote plant growth and PHE availability decrease, by engineering a soil (Technosol) using organic and/or inorganic amendments together with soils/wastes from the contaminated site. The combination of phytostabilization with geotechnologies can minimize the risk to both human health and the environment, while promoting solutions for waste management and circular economy. Although the combination of these strategies seems ideal, it is not without issues that have to be addressed, such as the highly important task of identifying the nature/amount of PHE, soil proprieties, climatic conditions and the PHE translocation factor of the species that could be stablished in a specific mining site for rehabilitation. In other words, for each contaminated site it is necessary to design a specific phytotechnology tailor-made for each situation. In the present study, it was evaluated the response of a highly drought tolerant legume, Lablab purpureus (L.) Sweet, which due to its multifunctionality (forage, food, ornamental and medicinal), can offer a wide range of revenue to areas that otherwise would be neglected for agricultural activities as is the case of São Domingos abandoned mine area, our study area. After Lablab growing in Technosols made with high contaminated soils (e.g. As, Pb, Cu, Zn) and organic/inorganic wastes, our findings show that Lablab accumulates PHE in the roots and the concentrations present in the shoots are safe for animal consumption, thus presenting a potential plant to rehabilitate highly contaminated sites using Technosols.

How to cite: Abreu, M. M., Monteiro, F., and Vidigal, P.: A green solution for the rehabilitation marginal lands: the case of Lablab purpureus (L.) Sweet, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5637, https://doi.org/10.5194/egusphere-egu2020-5637, 2020.

The speciation of chromium in waters and leachates obtained from soils and sediments has aroused interest in the last years. The element may be present in two oxidation degrees that have quite different toxicity. While chromium (III) is even essential for human beings due to its role in the metabolism of glucose and lipids, Cr(VI) is toxic due to its oxidant properties. The concentration of chromium in waters is usually of a few micrograms per liter, and the difficulty of carrying out the measurement at such low levels is further increased due to the distribution of the total element in the two mentioned forms. The technique commonly used nowadays for the purpose is inductively coupled plasma mass spectrometry (ICP-MS), a powerful analytical tool, but expensive both in acquisition and maintenance. Speciation, in addition, requires some type of previous separation or suitable strategy since the signal obtained by ICP-MS depends on the total amount of the metal present.

Recent advances in microextraction techniques have demonstrated that the determination and speciation is also possible by using electrothermal atomization atomic absorption spectrometry (ETAAS), an analytical technique which is of lesser cost than ICP-MS and is present in most laboratories worldwide. This communication summarizes some recent studies carried out in our laboratory based on the use of dispersive solid-phase microextraction to concentrate chromium. The small volume of liquid extract finally obtained can be injected into the electrothermal atomizer, and a very sensitive chromium determination is achieved. The extreme sensitivity in this way obtained is the consequence of combining the efficient preconcentration step with the sensitivity inherent to ETAAS measurement. Selectivity is also guaranteed by the characteristics of ETAAS. Speciation can be carried out by means of simple previous redox treatments without the need for a chromatographic separation. Three procedures are compared, one of them using graphene oxide as the active micro-solid phase, other based in the use of cellulose, an inexpensive reagent. Both procedures require a centrifugation step to separate the micro-solid phase from the supernatant. The third procedure uses freshly prepared ferrite particles and avoids the centrifugation step since the magnetic characteristics of the solid material permit an easy separation of phases with an external magnet. In all cases, chromium is measured after desorption from the micro-solid phase by a small volume of a suitable reagent. The limits of detection are close to 0.01 micrograms/L. The reliability of the three procedures is checked by using several reference samples with a certified chromium content. Data for the speciation of the metal are also given, a point that may be of practical interest for those involved in risk assessment or toxicity studies, since the dealers of the reference materials only provide the total chromium content.

How to cite: Hernandez Cordoba, M., Lopez-Garcia, I., Marín-Hernández, J. J., Muñoz-Sandoval, M. J., and Perez-Sirvent, C.: Modern approaches for the analytical speciation of chromium at very low concentration in waters and leachates , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6130, https://doi.org/10.5194/egusphere-egu2020-6130, 2020.

The modification of environmental conditions and the subsequent evolution of the ecosystems results in soil degradation or desertification, which is also caused by the abandonment of the countryside, poor agricultural practices and the socio-economic dynamics that nowadays presents the rural environment. Land degradation leads to loss of fertility, nutrients and vegetation cover and increased erosion, pollution, salinization and alkalinization. The effects derived from this situation aggravate, in turn, climate change, in a strongly intertwined dynamics that feeds back.

Degraded soils are recoverable through various strategies, among them good agricultural practices being especially relevant.  In this paper, the degree of desertification of several plots of soil that have undergone treatments for the incorporation of organic matter (sewage sludge, manure from different animals, composted plant remains) and their untreated counterparts (blank) is evaluated. To this end, desertification indicators (salinization, organic matter, phosphorus content) included in the LIFE AMDRYC4 Project have been used to monitor soil neutrality, as a measure of the global desertification suffered by a plot.

The results obtained clearly show an improvement in the soil characteristics following the application of the mentioned strategy for soil treatment. It is therefore concluded that soil degradation is mitigated by good agricultural practices, which leads to a decrease in erosion and salinization and an increase in organic matter, nutrient content, plant cover and the ability to sequester dioxide carbon.  Soils are not affected by polluting processes both in terms of potentially toxic elements and other emerging pollutants. The experimental data obtained indicate that soils in this way remediated can be used to reduce the concentration of greenhouse gases in the atmosphere and represent a good tool to fight against climate change.

How to cite: Martinez-Sanchez, M. J., Martinez-Lopez, S., Martinez-Martinez, L. B., Ortega, M., Hernandez-Cordoba, M., and Perez-Sirvent, C.: Improvement of soil characteristics making use of logical, good agricultural practices: purpose and results obtained in the LIFE AMDRYC4 Project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7439, https://doi.org/10.5194/egusphere-egu2020-7439, 2020.

Heavy metal contamination in soil is a major environmental issue intensified by rapid industrial and population growth. Understanding the spatial distribution of soil contamination by heavy metals in the ecosystem is a necessary precondition to monitor soil health and to assess the ecological risks. The main sources of heavy metals in soil are natural and anthropogenic sources. Natural sources are typically released of heavy metals from rock by weathering and atmospheric precipitation. Anthropogenic sources are related to industrialization, rapid urbanization, agricultural practices, and military activities. We analyzed a total of 358 topsoil samples (0–30 cm) collected in Golestan province in the northeast of Iran based on a regular square grid networks with 1,700 squares each sized 2.5 km²(random sampling within the grid). From these samples, we determined the spatial distribution of Cd, Cu, Ni, Zn, and Pb using random forest (RF). A multi-spectral image (Landsat 8), and environmental derivatives calculated from terrain attributes, climatic parameters, parent material, land use maps, distances to mine sectors, main roads, industrial sites, and rivers were used as covariates to predict the spatial distribution of concentrations of heavy metals. The multi-collinearity of the predictors was examined by the variance inflation factor (VIF), and a feature selection process (genetic algorithm) was applied to avoid noise and optimize the selected input variables for the final model. The predictive accuracy of RF model was assessed by the mean prediction error (ME), root mean squared error (RMSE), and coefficient of determination (R²) using 5-fold cross-validation technique. The results showed that the concentration levels (mg kg^-1) of Cd, Cu, Pb, Ni, and Zn varied from 0.02 to 2.75, 9.70 to 93.70, 6.80 to 114.20, 9.50 to 93.20, and 25.10 to 417.4, respectively. The best prediction performance was for Ni (RMSE=9.9 mg kg^-1 and R²=56.6%), and the lowest prediction performance for Cd (RMSE=0.4 mg kg^-1 and R²=28.0%). Environmental covariates that control soil moisture and water flow along with climatic factors were the most important variables to define the spatial distribution of soil heavy metals. We conclude that the RF model using easily accessible environmental covariates is a promising, cost-effective and fast approach to monitor the spatial distribution of heavy metal contamination in soils.

Keywords: Heavy metals; digital soil mapping; machine learning; random forest; spatial variation; soil pollution.

How to cite: Zeraatpisheh, M., Mirzaei, R., Garosi, Y., Xu, M., Heuvelink, G. B. M., Scholten, T., and Taghizadeh-Mehrjardi, R.: Feasibility of using environmental covariates and machine learning to predict the spatial variability of selected heavy metals in soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12378, https://doi.org/10.5194/egusphere-egu2020-12378, 2020.

The uranium mineralization from Fé mining area (Spain) contains sulfides, resulting mine wastes generators of acid mine drainage rich in potentially hazardous elements (PHE). The improvement of the physicochemical characteristics and biogeochemical processes of sulfide mine tailings as well as their socioeconomic valorisation can be achieved by the application of a green technology based on circular economy: Technosol. The efficiency of the application of a superficial layer of a designed Technosol with specific properties to the rehabilitation of the sulfide tailings from Fé mining area was tested. Also, the risk assessment of the land recovery by this technology to pasture was evaluated through a microcosm experiment.

After 20 months of the Technosol application in the field, composite samples of Technosol, recovered tailing (bottom of the Technosol) and tailings without recuperation (control tailing) were collected. These samples were used for microcosm assay and characterized for pH, electric conductivity, fertility, PHEs concentration in total fraction and available fraction extracted with rhizosphere-based method. The substrate effect on development of Lollium perenne and Trifolium pratense (visual signs of phytotoxity, percentage of plant cover and dry shoots biomass) and multielemental composition in their of shoots was evaluated in microcosm assay under greenhouse conditions.

Mine wastes from control tailing had pH ≈4 and high total concentrations of several PHEs (g/kg; Al: 46.2; As, Co and Pb: 0.02-0.03; Cu: 0.04; Fe: 63.2 Mn: 1.3; Ni and Zn: 0.1-0.2). Potentially toxic concentrations of Co, Mn and Ni were identified in the available fraction pointing out the serious environmental risk posed by the control tailing. These chemical characteristics together lack of structure iin mine wastes from control tailing contributed to total inhibition of Trifolium germination and a significant diminution of Lollium growth. Both species growing in Technosol and recovered tailing produced significant plant cover and quite similar amounts of shoot biomass.

The improvement of the overall physicochemical properties in the recovered tailing materials (e.g. the decrease of the hazardous element concentrations in available fraction, and the improvement of the fertility and structure) allowed a quick and secure plant cover with pasture species. The results evidenced the efficiency of the designed Technosol in the sulfide mine tailing rehabilitation and potential land recovery to pastures.

The authors thank ENUSA for technical cooperation and providing the study area and soil samples.

How to cite: Arán, D., Santos, E., Abreu, M. M., Antelo, J., and Macías, F.: Pasture species behaviour on sulfide mine tailings rehabilitated with a designed Technosol, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12598, https://doi.org/10.5194/egusphere-egu2020-12598, 2020.

Mining of Zn and Pb metal ores, mainly blende (ZnS) and galena (PbS), in Cave del Predil (I) valley from 1800 to 1991 produced a huge amount of tailings (estimated about 20 •10⁶ m³). Such tailings had been prevalently accumulated close to the Rio del Lago creek or used to reshape the excavation area. These tailings are rich in toxic metals (i.e. Pb, Zn, Tl) under different chemical and mineralogical forms (sulphide, sulphate, carbonate, etc.), representing a potential health risk to the local ecosystem. The gradual oxidation of sulfide minerals tend to mobilize these toxic metals, that in part are retained due to the calcareous nature of rock, but they are partially leached to the trans-boundary Slizza/Gailitz creek.

Phytocapping represents a promising strategy to reduce the dispersion of contaminants into the air as dust particles and to groundwater, but the establishment of a permanent vegetation is strongly unpaired by the toxicity of this substrate. Immobilization techniques, using abundant, rather inexpensive, natural and/or industrial by-products, may offer an effective alternative to conventional methods to reduce the metals mobility and bio-availability.

The aims of this study are to assess: (i) the effect of metal immobilization treatments on mine tailings and (ii) the uptake and translocation of Pb, Zn and Tl in the metalliferous plant species Biscutella laevigata (L.) and Silene vulgaris (L.).

The mobility of toxic metals has been evaluated either in batch extractions (synthetic rain, TCLP) or by leaching columns in the native mine tailings and in tailings treated by different amendments (zero-valent Fe, Fe(II)+digestate, biochar).

The plants were collected respectively upstream (2 stations) and downstream (5 stations) the mining site in the sediment banks of Slizza/Gailitz creek. In each stations, six specimens were sampled for each species. In addition, at each plant collection point, a composite bulk soil and rhizospheric soil sample was excavated along the 0–20 cm profile. Plant specimens were divided into two fractions: root apparatus and aboveground biomass. The soil and plant samples were oven-dried and acid-digested in a microwave oven. Total Cu, Fe, Ni, Pb, Tl and Zn contents in the extracts were determined by ICP-MS. The bioavailable metal fraction of Cd, Pb, Tl and Zn was determined by selective extractants.

Addition of Zero-valent Fe showed the strongest decrease of leached metals trough the soil columns, whereas the addition of Fe(II)+digestate strongly increased the concentration of metals in leachates, probably because of the acidification caused by Fe oxidation/precipitation.

Biscutella laevigata and Silene vulgaris are metal tolerant species. Pb concentration in B. laevigata ranged between 0.01-669 and 0.01-234 mg kg^-1, respectively in roots and shoots. In the same fractions of S. vulgaris Pb ranged between 0.01-891 and 0.01-208 mg kg^-1. As for Zn, root and shoot concentration in B. laevigata were 13.4-1461 and 20.6-3390 mg kg^-1 respectively, whereas in S. vulgaris 2.36-1829 and 17.2-1590 mg kg^-1. The response of metal uptake and accumulation in plant species grown in treated mine tailings are currently under observation.

How to cite: Contin, M., Fellet, G., Lizzi, D., Piani, B., De Nobili, M., and Marchiol, L.: Leaching and plant uptake of toxic metals in abandoned mine tailings in the Cave del Predil (I) mining site and Rio del Lago valley, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13346, https://doi.org/10.5194/egusphere-egu2020-13346, 2020.

Dibenzothiophene (DBT) is a sulfur-containing PAH typically used as a model chemical to study biodegradation of PAHs and bioremediation. The effects of using different carbon sources (sodium gluconate, glucose, sodium pyruvate, sodium acetate and glycerol) as a co-substrates were investigated during DBT biodegradation by Burkholderia sp. C3 with respect to (i) bacterial (Burkholderia sp. C3) growth, (ii) DBT biodegradation kinetics, (iii) secretion of the biosurfactant rhamnolipids (RLs) and (iv) RLs characterization. This is the first study showing a direct association between RLs biosynthesis and DBT biodegradation induced by different carbon sources in Burkholderia species. The results indicated that bacterial growth supported by gluconate, glucose, pyruvate and glycerol, and the maximal OD600 achieved in presence of gluconate and glycerol. Glycerol and pyruvate significantly enhanced DBT biodegradation after 7 days, while glucose inhibited DBT biodegradation. RL is a glycolipid biosurfactant extensively studied in Pseudomonas species and its potential in the bioremediation field. Glycerol can induce C3 produce at least four RLs by HPLC separation and MALDI-TOF/TOF identification. Glycerol stimulated a dual function in C3 as a RL producer and a DBT degrader. The increase of RL biosynthesis and secretion facilitated biodegradation of DBT in C3. Additionally, RLs reduced the surface tension of cultures with glycerol which increased the bioavailability of DBT for Burkholderia sp. C3 to utilize it. The direct utilization of crude glycerol for bacteria to degrade pollutants must be cost-effective and environmentally friendly.

How to cite: Cao, J., Ni, J., and Li, Q. X.: Effect of different carbon sources on Dibenzothiophene degradation and Rhamnolipids production by Burkholderia sp. C3, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14938, https://doi.org/10.5194/egusphere-egu2020-14938, 2020.

In mining areas of the Moscow brown coal basin, soils are impacted by acid mine drainage (AMD), solid sulfide-bearing mine wastes and carbonaceous particles. Spoil heaps of overburden rocks and subsidence areas over the mined space are formed at abandoned mine fields. Most of the spoil heaps have not been remediated and erode intensively due to physical and chemical properties of waste rocks. AMD of sulfuric acid, Al and Fe sulfates as well as pyritized material, entering from the eroded spoil heaps, results in morphological changes in soil properties. Other environmental concern is the formation of subsidence areas over the mined space due to the dewatering of abandoned сoal mines. It results in alteration of the soil water regime. On deluvial and proluvial dump tailings around spoil heaps technogenically transformed soils are common.

The aim of the study was to examine the post-mining evolution of natural soils under the impact of supply of tecnhogenic material from the spoil heaps and changes of the terrain in abandoned sulfur coal mining areas.

We investigated two key sites within abandoned coal mine fields in the central part of the Moscow basin (the Tula region, Russia). Prevailing natural soils are Greyic Phaeozems and Haplic Chernozems (WRB 2014) (Grey forest and Leached Chernozems in Russian classification).

Soil samples and soil solutions were analysed for (acid-base properties, content and composition of readily soluble salts, content of Fe²⁺ and Fe³⁺, H⁺ and Al³⁺, carbonates, composition of exchangeable cations, particle size content, total content of S, Al, Fe and organic carbon). Soil solutions were displaced by ethanol (Ishcherekov-Komarova method, Russia) (Snakin et al. 2001). The level of saturation of soil solutions by gypsum, iron and aluminum hydroxides was evaluated.

Properties of newly formed soils differ significantly from natural soils. We identified the transformation of the composition of soil solutions. Key geochemical processes at mine sites in soils were:  (1) acidification and Fe-Al-SO₄ salinization of soil profile along with the increment in H⁺ and Al³⁺ ions content; (2) cation exchange, leading to displacement of Cа²⁺ and Mg²⁺ ions by Al³⁺, H⁺, Fe²⁺ and, perhaps, by Fe³⁺ in soil ion-exchange complex; (3) alteration of radial differentiation of organic carbon and carbonates in soils; (4) mineral transformations.

  Semi-hydromorphic soils with signs of gleying and peat accumulation were formed in subsidence areas. In Greyic Phaeozems the intensification of podzolization process could be noted. In Haplic Chernozems gypsum neoformations (neogypsans) were observed. Post-technogenic soils have no analogues in natural forest-steppe landscapes of the Russian Plain.

How to cite: Kostin, A., Krechetov, P., Chernitsova, O., and Terskaya, E.: Changes in soils of Central Russian forest-steppe under the impact of sulfur coal mining (the Moscow basin), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17954, https://doi.org/10.5194/egusphere-egu2020-17954, 2020.