In urban regions, surface dust and topsoil can be used as indicators of metal pollution. Numerous studies have been conducted in different locations throughout the world to assess metal pollution and associated environmental and human health risks, but none have been conducted in Afghanistan's Kandahar region. The purpose of this study is to examine the environmental and health risks of metal concentrations (As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) in topsoil samples of sampling site. The average metal concentrations in the topsoil slightly exceeded their corresponding background values in Upper Continental Crust (UCC). Top soil samples showed low contamination for Cd, Co, Cr, Cu, Ni, Pb, V, Zn and considerable to very high contamination for As. Pollution load indices (PLI) demonstrated that all sampling sites are at a high load of metal pollution (PLI >1) indicating deterioration of soil quality.  

According to Geo-accumulation Index (Igeo), topsoil samples fall under uncontaminated category for Co, Cr, Cu, Ni, Pb, V, Zn and moderately to heavily contaminated for Cd and heavily to extremely contaminated for As. Ecological risk values suggested that study area had low risk for Co, Cr, Cu, Ni, Pb, V, Zn while considerable to high risk for Cd and high to very high risk for As. According to the health risk assessment, ingestion is the major pathway for non-carcinogenic risk and children are at more risk as compared to adults. Fall outs of high ammunition usage, wear and tear of heavy duty vehicles and fossil fuel consumption seems to be responsible for the high levels of metals in topsoil of Kandahar region. More such studies need to be conducted with more spatial coverage to identify contaminated areas and subsequent remediation to safeguard human health and ecosystem.

How to cite: Monib, A. W. and Yadav, S.: Trace metals in the topsoil of Kandahar region, Afghanistan and their associated health and ecological risk, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-620, https://doi.org/10.5194/egusphere-egu23-620, 2023.

Preliminary lead and strontium isotopic compositions of soil profiles collected from highly urbanized and industrialized sites were measured to develop a survey of possible sources of lead. Potential lead and strontium sources range from geologic (e.g., bedrock and bedrock-derived soils) to anthropogenic (e.g., vehicular traffic and legacy of burning fossil fuels, heavy metal smelters, manufacturing of paint, plastics, lubricants, residential development, agricultural amendments, atmospheric deposition, etc.). Twenty-one soil profiles were sampled (6 samples/profile site to a depth of 60 cm). Lead concentrations and isotopic compositions (thermal ionization mass spectrometry and inductively coupled mass spectrometry) were measured for bulk soils, acid-leachates, and residues of bulk leaching. The soils include rock-forming silicates (e.g., feldspars, quartz, mafic minerals) and secondary minerals and amorphous materials (e.g., iron-oxyhydroxides, clays, organics). The lead isotopic compositions of acid-leachates of the soils represent lead adsorbed to mineral surfaces or held in soluble minerals (for example, iron- and manganese-hydroxides, and carbonate); soil residues likely reflect feldspar and other rock-forming minerals in bedrock-derived soils. The soils plot as a broad band in ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb space extending from radiogenic values (typical of rock-derived lead (bedrock and bedrock-derived soils) to lower ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb values that likely indicate anthropogenic/industrial types of lead (for example, heavy metal aerosols, leaded paint, agricultural amendments). Lead isotopic values of the Los Angeles soils form a broad band  intermediate between values of lead ores from the highly radiogenic U.S. Mississippi Valley type deposits and less radiogenic lead deposits of China.  Labile lead (leach fractions from soils) shows a moderate range in values of ²⁰⁶Pb/²⁰⁷Pb ~1.1671 to 1.1928, and ²⁰⁸Pb/²⁰⁷Pb ~2.4319 to 2.4498. Residues overlap the leach compositions and extend to more radiogenic values (rock-derived lead). The lowest values of ²⁰⁶Pb/²⁰⁷Pb (~1.1754) and ²⁰⁸Pb/²⁰⁷Pb (~2.4375) and highest lead contents (~4000 ppm) were measured in soils near where lead was smelted. Higher values of ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb and lower values of lead (~25 ppm) are found in other bulk soils and may represent lead derived from bedrock. The variations in lead isotope values in the soil profiles are consistent with contributions from distinct sources, which include both natural and anthropogenic lead.

How to cite: Ayuso, R., Foley, N., Johnston, J., Indela, R., Jackson, J., and Bickerstaff, D.: Pb and Sr Isotopic Compositions of Soils in Urbanized Industrial Settings, East Los Angeles, California, U.S.A: From Geogenic to Anthropogenic Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8303, https://doi.org/10.5194/egusphere-egu23-8303, 2023.

The city of Huelva in SW Spain is known to be affected by air pollution derived from industrial activities^1,2 and the soils surrounding the industrial estates contain anomalous concentrations of potentially toxic elements (PTEs)³. This study focuses on the urban soils of Huelva covering 33 sampling points in the principal public parks, playgrounds, and green areas. We evaluated potential contamination of the soils comparing Al-normalized values, contamination factor (CF) with respect to background values, and regulatory levels after analyzing the concentrations of PTEs (Cu, Zn, Co, As, Cr, Cd, Pb and Ni) in the topsoil, and further we assessed the potential toxicological effects using Lactuca Sativa L. bioassay and human exposure modelling. Al-normalized data highlighted anomalous high concentrations for Cu, Zn, As, Cr, and Pb. Moreover, CF values higher than one were found in 88% of the soils for Cu, 85% for Zn, 30% for Co, 45% for A36% for Cr, 100% for Cd, 45% for Pb, and 18% for Ni with elevated maximum concentrations (2083, 790, 16, 51, 153, 5.0, 293, and 32 mg/kg, respectively). The regulatory values for As (36 mg/kg) and Pb (275 mg/kg) were exceeded in soils of ten sampled urban areas. However, the germination and root elongation bioassays with Lactuca sativa L. did not show phytotoxicity in any of the tested soils, and health exposure modelling did not present risk for toxic effects nor for carcer. This study highlights the vicinity of the industrial area as a risk factor for the accumulation of PTEs in urban soils and previous studies corroborate this^3,4. We recommend monitoring of the urban soils of Huelva, further investigations on the soils that can be declared as polluted soils according to this study, and also to increase the number of toxicity bioassays with different organisms and to include different exposure routes for human health risk.

Acknowledgment

This work has been financed by the EMC21_00056 project granted by the Council of University, Research and Innovation of the Regional Government of Andalusia.

References

• Parviainen, A., Casares-Porcel, M., Marchesi, C. & Garrido, C. J. Lichens as a spatial record of metal air pollution in the industrialized city of Huelva (SW Spain). Environ. Pollut. 253, 918–929 (2019).
• Fernández-Camacho, R. et al. Geochemical characterization of Cu-smelter emission plumes with impact in an urban area of SW Spain. Atmos. Res. 96, 590–601 (2010).
• Guillén, M. T. et al. Heavy metals fractionation and multivariate statistical techniques to evaluate the environmental risk in soils of Huelva Township (SW Iberian Peninsula). J. Geochemical Explor. 119–120, 32–43 (2012).
• Guillén, M. T., Delgado, J., Gómez-Arias, A., Nieto-Liñán, J. M. & Castillo, J. Bioaccessibility and human exposure to metals in urban soils (Huelva, SW Spain): evaluation by in vitro gastric extraction. Environ. Geochem. Health 44, 1501–1519 (2022).

How to cite: Parviainen, A. and Martín-Peinado, F. J.: Urban soil pollution and assessment of human health risks in the industrialized city of Huelva, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14865, https://doi.org/10.5194/egusphere-egu23-14865, 2023.

Wheel weights used for balancing tires are among the top five anthropogenic lead (Pb) sources contaminating the surface environment in modern society. In the present study we characterized size, shape, and stages of degradation of wheel weights from the U.S.A. to understand abrasion, dissolution, and transfer of metallic Pb. In a previous study of wheel weights [Ayuso and Foley 2020, Jour. Geochem Explor.], we identified partially abraded and chemically corroded textures with coatings of reconstituted Pb particles, including litharge (PbO) and/or plattnerite (PbO₂), in a matrix of clays, feldspars, silica, and iron-oxides. New examples of finely comminuted Pb-rich particles (by Field Emission-Scanning Electron Microscopy) include platy sheaths, rods, and tabular crystals up to about 30 µm in length, slender needles less than ~0.5 µm in width, and submicrometer-sized flakes, chips, and masses of indeterminate form.  Abraded Pb oxide particles are mostly <1 µm-size consisting of acicular needles and hair-like crystals; the size and particle shapes can have significant adverse health impacts if ingested, inhaled, or imbedded in the human body. Pb isotope analysis (by Thermal Ionization Mass Spectrometry and High Resolution Inductively Coupled Plasma Mass Spectrometry) provides a way to identify the main lead exposure pathways. Lead isotopic ratios for wheel weights (bulk and acid-leachates) in plots of ²⁰⁶Pb/²⁰⁷Pb (~1.130-1.230) vs. ²⁰⁸Pb/²⁰⁷Pb (~2.410-2.470) are analytically indistinguishable. The ²⁰⁸Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁷Pb data implicate a lead source from Mississippi Valley-type deposits (U.S.A.) and a less radiogenic endmember which may link to an international lead source, such as ore deposits of China. Degradation of wheel weight particles will influence the Pb isotopic composition of local surface and groundwater regardless of whether the contribution is from solid particles derived from grain erosion or from dissolved forms of Pb. Geochemical modelling supports the argument that pH is a primary factor in lead corrosion; however, the range of sizes (<63 µm) and morphologies (needles, hairs) identify an additional health concern associated with intake of weathered products of Pb components found in water and soils. The legacy of past and current uses of Pb metal in manufactured products will continue to be of global concern because these industrial products remain readily available through both primary and secondary global markets.

How to cite: Foley, N. and Aysuo, R.: Surface topography, mineralogical survey, and Pb isotopic compositions of vehicle wheel weights: Major heavy metal contaminants of roadways, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2425, https://doi.org/10.5194/egusphere-egu23-2425, 2023.

This study investigated the effect of hydrogen peroxide treatment on the removal pH for Fe, Al, and Mn and sludge production in the lime neutralization process. In the laboratory, the AMD collected from the coal mine was oxidized with 5% H₂O₂, and then neutralized to pH 3, 5, 7 and 9, respectively, with 20% lime slurry. In the control experiment, the same neutralization experiment was performed without H₂O₂ treatment. During the experiment, the supernatant was measured for pH and Eh and analyzed for Fe, Al, Mn, Ca and SO₄^2- ions. Simple neutralization without H₂O₂ treatment up to pH 8 resulted in almost 100% Fe (<0.3 mg/L), Al (<0.3 mg/L), and Mn (2 mg/L) removal. Neutralization with pre H₂O₂ treatment also eliminated Fe and Al at pH 6 to the same removal efficiencies and Mn remained at 15 mg/L. The use of lime was 17% less and the weight of sludge was 35% less, and the volume of sludge decreased by 47%. As a result of evaluating the pH-Eh-Fe diagram for hydrogen peroxide/lime neutralization facilities, it was evaluated that Fe could be removed at pH 5-6. It can be concluded that neutralizing up to pH 6 after oxidation effectively minimizes the amount of sludge generated by removing Fe and Al and suppressing gypsum production.

How to cite: Cheong, Y., Cho, D.-W., Yim, G., and Jang, J.-Y.: Evaluation of water quality change and sludge generation according to hydrogen peroxide treatment during lime neutralization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2217, https://doi.org/10.5194/egusphere-egu23-2217, 2023.

The exploitation of mineral resources is a fundamental activity for the development of societies, but the importance of the alterations caused to the environment has not been considered when carrying out these exploitations. In the case of metallic mining, sulphide oxidation and leaching of potentially toxic elements (PTEs) lead to soil and water pollution.

Sierra Minera of Cartagena-La Unión (SE, Spain) has historically been a major mining district. Technological development caused production to rise during the second half of the 20th century, leading to an increase in tailings dumps, producing one of the biggest ecological disaster on the Mediterranean coast.

Sediments from Portman Bay were collected during the Pilot Project for its regeneration (2008). Samples have been analyzed in 12 cores of 10 meters deep, with one sample every meter. Two cores were selected and analyzed to a depth of 24 meters in order to reach the original bedding material and thus be able to make a 3D model of the extent of the contamination at depth.

The total PTEs content was determined after an acid digestion. In addition, a characterization of the mineralogical composition has been carried out by XRD, both in powder samples and oriented aggregates for the determination of bulk and clay mineralogy respectively.

The materials studied showed sandy texture, except collected close to the discharge point, as in the core located in the internal area of the Bay, where the texture is finer. The total PTEs content is high and follows the following order of concentration: Zn > Pb > As > Cu > Cd.

The mineralogical results showed the presence of quartz, feldespars and phyllosilicates in most of the samples. The rest of the minerals present in the samples correspond to different phases of Fe as sulphides (pyrite), oxides (hematite and magnetite), oxyhydroxides (goethite), carbonates (siderite) and sulphates with different states of hydration, such as jarosite. Gypsum appears in most of the samples, regardless of their depth. The presence of jarosite is relevant in the surface samples of cores in the inner part of the bay, as well as in the first line of cores located near the dumping point. In the case of cores located further away from the coastline, the presence of this phase has been detected both at surface and at depth.

Clay mineralogical data revealed that samples with mining residues contain greenalite, chlorite and mica-illite as main minerals, with minor amounts of minnesotaite, kaolinite and smectite. On the other hand, in the samples from the deeper zones corresponding to the bedding materials, the phyllosilicates found are mica-illite, kaolinite and chlorite in order of abundance.

The statistical integration of the results has allowed the selection of quartz, pyrite, siderite and arsenic as representative variables for the 3D model. Taking into account that the current reclamation project in the bay includes mobilization of part of the waste to a mining cut, the use of these 3D models is very useful as a complement to the geochemical and mineralogical characterization.

How to cite: García-Lorenzo, M. L., Arroyo-Rey, X., Ferri-Moreno, I., Esbrí, J. M., Ortiz Zarco, F. J., Pérez-Sirvent, C., and Martínez-Sánchez, M. J.: 3D Characterization of potentially toxic elements dispersion in Portman Bay using mineralogical and geochemical indicators, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7543, https://doi.org/10.5194/egusphere-egu23-7543, 2023.

Measurements of acid volatile sulphide (AVS) and simultaneously extracted metals (SEM) in sediments are used to assess the toxicity of metals to native benthic organisms. The AVS is obtained from the sulphides contained in the sediments by addition of acid and the SEM are the metals extracted during the AVS treatment. The AVS/SEM method reflects a more precise estimation of sediment toxicity to benthic organisms than "total" metal values (cadmium, copper, lead, nickel and zinc) by measuring a "bioavailable" fraction of the metals present. Sediment toxicity is assessed by calculating the sum of the SEM (µmol/g dry weight) divided by the AVS concentration (in the same units): a ratio less than or equal to 1 indicates that the metals in the sediment are not bioavailable, while a ratio greater than 1 indicates that the metals are bioavailable.

In this case, they are applied to soils containing mining waste and marine sediments that were buried under these inputs in Portman Bay (SE Spain) and compared with the values obtained from the ecotoxicity tests used: microtox, ostracodes and gambarus for sediments and phytotoxicity tests for topsoil samples.

The results confirm the ecotoxic characteristics of some of the samples evaluated and also allow an approximation to be made of the impact that neighbouring materials may have if subjected to AMD, when there is intense precipitation and the waters of the wadis reach the bay with the runoff from the neighbouring mining areas.

How to cite: Pérez-Sirvent, C., Martínez Sanchez, M. J., Martínez Lopez, S., Martinez Martinez, L. B., Hernandez Cordoba, M., Hernandez Perez, C., Banegas Garcia, A., el Jamaoui, I., Bech, J., and Garcia Lorenzo, M.: Acid mine drainage and ecotoxicity in soils and sediments., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9474, https://doi.org/10.5194/egusphere-egu23-9474, 2023.

Mining areas are so complex that it is sometimes difficult to differentiate between anthropogenic contamination and geogenic anomalies. This is the case in the so-called Sierra de Cartagena-La Unión, which constitutes a mining district of Ag, Pb, Zn, Fe in stratabound sulphide deposits that have been exploited for more than three thousand years. Since the closure programme was implemented in 1991, the area has remained abandoned. This results in runoff from extreme rainfall events, as well as wind action, allowing the transport of dissolved or suspended particles and pollutants from mining areas to the plain of Campo de Cartagena, the Mar Menor and the Mediterranean Sea. In this area, arsenic pollution is one of the main environmental and public health problems. In general, arsenic levels in uncontaminated soils rarely exceed 10 mg/kg, the proposed Generic Reference Level (GRL) being 7.84 mg/kg for the Region of Murcia. In exclusion zones, As concentrations exceed 300 mg/kg, reaching in some cases 5000 mg/kg (coinciding with accumulations of mining waste, ponds, dumps, etc.).

The main objective of this work was to evaluate the potential risk to humans, through the main route of entry, ingestion, represented by the soils of the Rambla del Beal basin (SE Spain) and its mouth in the Lopoyo Wetland (Mar Menor, SE Spain), taking into account:

- Total As content in four different soil fractions (˂2mm; ˂250µm; ˂100µm; ˂63µm).

- Bioaccessible arsenic content in four different soil fractions (˂2mm; ˂250µm; ˂100µm; ˂63µm).

- Two possible adult land uses (agricultural and residential) and one possible child land use (residential).

For the determination of As bioaccessible, in vitro extraction methods were used. Among the various in vitro methods to assess the relative bioavailability of existing metals, the Solubility Bioaccessibility Research Consortium (SBRC) method was selected, as it provides an adequate relationship between bioavailability and bioaccessibility of arsenic, with a high correlation with the results obtained in vivo experiments, distinguishing two phases, stomach and intestinal.

In the area studied, the Lopoyo Wetland is the area that presents the greatest risk to the health of people (both children and adults). It is an area that requires priority intervention for its recovery. The arsenic contamination present and its mobility in this reduction-oxidation zone represents an unacceptable risk for both public health and the ecosystem.

The results highlight the importance of carrying out risk analysis studies on human health at sites potentially contaminated by carcinogenic trace metals such as arsenic, taking into account the concentration of bioaccessible As.  According to the results obtained when the study is carried out with the total concentration of arsenic, i.e. without bioaccessibility, the results of unacceptability of the carcinogenic risk and of the systemic hazard are much higher than those obtained with bioaccessibility, independently of the granulometric fraction on which the determination is carried out. Moreover, these results are reproducible for all possible uses (scenarios) of the site.

How to cite: Hernandez Cordoba, M., Martínez Lopez, S., Martinez Martinez, L. B., Martínez Sanchez, M. J., Perez Sirvent, C., Hernandez Perez, C., Banegas Garcia, A., el Jamaoui, I., and Bech, J.: Assessment of bioaccessible As in a wetland with mining influence (Mar Menor, SE Spain)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9901, https://doi.org/10.5194/egusphere-egu23-9901, 2023.

In order to predict the future behaviour of technosols designed for the remediation of sites contaminated with mining waste, a pilot experiment was carried out in containers under an enclosed building.

One-metre cubic polyvinyl chloride (PVC) containers were used and filled with soil of the different types that are abundant on the site. Four soil types were selected with different textures (sandy to silty-clay), different mineralogy and different PTE content. Soil mixtures were also prepared with limestone filler at different proportions (30, 40 and 50 %).

These containers were subjected to a humidity and drying process, simulating the rainfall conditions that the site receives as an average annual value, in 10 successive cycles, maintaining the experience for 4 years. The drains obtained were analysed and their corresponding crystallised phases were obtained and characterised by XRD and electron microscopy. The metals determined were Fe, Cd, Cu, Pb, As and Zn.

This experiment allows us to differentiate the behaviour of the selected soils with respect to humidity, since the untreated soils with a clayey loam texture are AMD producers, with very low pH and a high mobilisation of metals. In contrast, sandy textured soils and soils containing 30 % or more limestone filler have a pH close to 7 and small metal contents close to the limit of quantification.

Efflorescences are more abundant in those leachates rich in Zn and Fe, being copiapite, hexahydrite, bianchite and gypsum the main soluble phases associated with these leachates.  Finally, the percolates with a higher salt load correspond to the third percolation carried out approximately nine months after the start of the experiment.

How to cite: Martinez-Sanchez, M. J., Garcia Lorenzo, M., Martínez Lopez, S., Martinez Martinez, L. B., Hernandez Cordoba, M., Banegas Garcia, A., Bech, J., Hernandez Perez, C., el Jamaoui, I., and Perez Sirvent, C.: Evaluation of Amd production under experimental conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11706, https://doi.org/10.5194/egusphere-egu23-11706, 2023.

The rehabilitation of the Lousal mine in Portugal, carried out during September-November 2021 within the framework of the LIFE RIBERMINE project, is the first designed and built rehabilitation project in Europe where geomorphic reclamation methodologies have been combined with solutions aimed at addressing the problems caused by the generation of acid mine drainage and the mobilisation of potentially toxic elements (PTE).

To assess the success and impact of the rehabilitation actions on the hydrochemistry of surface and groundwater in Lousal, four groundwater samples and two surface water samples were collected in May 2022. In each of the water samples, in situ dissolved oxygen, pH, conductivity was measured and PTEs and cation-anion content analysis were carried out by ICP - MS in an external laboratory. The post mine rehabilitation effects of recent less acidic leachates with lower metallic loads have not yet reflected correction to the pH or EC values, but they are significant in terms of oxidation reduction potential and presence of PTEs.

The geomorphic evolution and development of vegetation in the reclaimed area has been monitored since the conclusion of the reclamation actions in November 2021. After the completion of the rehabilitation work, localised rilling processes were observed in areas where surface run-on entered the rehabilitation topography from adjacent areas. These erosive forms were corrected by extending limestone blocks over the eroded areas to create additional open limestone channels that manage incoming surface runoff and minimise its erosive potential. Throughout 2022, no signs of active erosion have reappeared in the restored area, demonstrating the success of the physical stabilisation actions applied in the intervention area.

Vegetation has successfully developed during the year 2022, after manual sowing in November 2021. Currently, the intervention area is almost completely covered with herbaceous vegetation, with the exception of some small areas where the density of vegetation is lower.

It is expected that the data and information obtained from the continued monitoring of this pioneering mine rehabilitation project will provide new knowledge and methodological innovations that can be applied to future mine rehabilitation projects around the globe with characteristics similar to those of the Lousal mine.

How to cite: Esbrí, J. M., Sanchez-Donoso, R., Muntaner, L., Martins, M., García-Lorenzo, M., Pereira, A. M., Pinto, A., Relvas, J., Lillo, F. J., Tejedor, M., and Martín-Duque, J. F.: First monitoring data of the post-project of geomorphological and geochemical rehabilitation in Lousal (Portugal), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11874, https://doi.org/10.5194/egusphere-egu23-11874, 2023.

All climate change predictions foresee a rise in sea level in the coming decades. Estuaries are environments particularly affected by this change due to their biodiversity. The Estuary of Huelva (SW Iberian Peninsula) is one of the most vulnerable ecosystems on the coastline on a global scale because it represents a transition zone between an acid fluvial environment severely polluted by acid mine drainage and alkaline seawater. Sediments and marsh soils are rich in iron and aluminium precipitates, which are highly reactive due to their nano-particle size. They also act as sinks for numerous pollutants, particularly arsenic. This research focuses its attention on the study of the set of geochemical and mineralogical processes that affect the mobility of metals and the stability of the particulate material under estuarine mixing, especially those processes that would be triggered by a foreseeable rise in sea level. Moreover, this study provides insight into the high contribution of the acid mine drainage discharges to the release of other elements (S, Zn, Cd, Ni and Co) to the coastal areas, as their initial concentrations behaved conservatively in mixing solutions with no participation in sorption processes. Some potentially toxic elements that remain mobile after reaching the estuary, finally end up to the Atlantic Ocean contributing significantly to the total pollutant loads and threatening the environmental conditions of coastal areas. Knowing the stability and mobility of pollutants in the estuarine areas that will be flooded in the next years according to most predictive models of climate change is essential for the design of adaptation strategies and minimization of impacts on the estuarine environment.

Acknowledgements

This work was supported by the Spanish Ministry of Science and Innovation under the research project TRAMPA (PID2020-119196RB-C21).

How to cite: Pérez-López, R., Millán-Becerro, R., Basallote, M. D., Macías, F., Ruiz Cánovas, C., and Nieto, J. M.: Geochemical processes controlling the partitioning of metals between water and sediments / marsh soils in an estuary affected by acid mine drainage leachates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13800, https://doi.org/10.5194/egusphere-egu23-13800, 2023.

Circular economy is based on the re-use of wastes. However, it also implies the application of solutions that can help to reduce the environmental and climate change impacts. On the one hand, the preparation of materials for construction from mining activities generates wastes, for instance in marble and stone industry. On the other hand, the use of these materials in construction also generates wastes, construction and demolition wastes (CDW), which account for more than a third of all waste generated in the EU. In the case of the SE of Spain, stone preparation (cutting, polishing, etc…) produces fine and coarse wastes, mainly from carbonate rocks and secondary from granites. The large building activity produces residues in a wide variety of materials (concrete, bricks, wood, glass, metals and plastics). 
Mining restoration could be an opportunity to reuse those materials, as many mining holes are abandoned and need to be refilled before the preparation of a soil cover and landscape recovery.
In this work, it has been studied the restoration of an ancient mining hole (up to 10 meters depth and 21000 m²), situated in the SE of Spain under a BSk climate -Köppen and Geiger classification-, with marble wastes and CDW, and finally the formation of a Technosol (IUSS Working Group WRB) which can support a vegetation cover. Several actions were done as follow: refilling of the mining hole first with marble wastes (calcareous materials mainly of different sizes), the second was the addition of CDW and the third was the mixing of CDW with topsoil (approximately last 50 cm depth of surface restoration) forming the surface and conditioning the topography to reduce soil erosion. This action was accompanied by the construction of a central drainage stone filled canal (50 cm depth). After two years, Pinus halepensis vegetation was introduced (261 pine trees). Two years later, soil samples were taken (0-5 cm to measure bulk density and 0-20 cm depth to measure pH, electrical conductivity and organic matter) in eight selected points distributed equidistant in the restored area. 
The results showed that the soil had a slightly basic pH, but not homogeneous along the surface (from 8.13 to 8.89). In the case of the electrical conductivity, the variation between samples was greater (0.49 to 2.41 dS/m) and probably controlled by the lithology of the area, in the north close to Triassic formations with soluble gypsum formations and in the middle to the south to calcareous rocks. The organic matter (between 1.13 to 1.59 %) and the bulk density (1.40 to 1.47 g/cm³) were more homogeneous in the restored area. The survival of the pine trees was successful and more than 80%, considering no irrigation applied excepting the first month.
The use of this materials could be of interest to reduce the impact, favoured the circular economy and restoration of ancient mining areas, recovering the landscape and the soil functions.

How to cite: Navarro Pedreño, J., Rodríguez Espinosa, T., Carpena López, A., Jordán Vidal, M. M., Gómez Lucas, I., and Bech Borrás, J.: Restoration with mining wastes and construction and demolition wastes to improve circular economy and soil functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15081, https://doi.org/10.5194/egusphere-egu23-15081, 2023.