Search Results (10)

The European Union prioritizes nature restoration, particularly in semiarid Mediterranean regions where integrating degraded coal mining areas into the landscape is essential. This involves maximizing water use and controlling runoff. A rehabilitation project in a former mining quarry was conducted with the objective of constructing suitable Technosols to support vegetation, limit erosion, and reduce rehabilitation costs. To prepare the substrate, mine spoils (saline materials) were mixed with residual materials, including discarded lignite powder, sewage sludge, pig slurry, and straw. Pig slurry was also introduced as a mulch in the experiment. A complete randomized block design with three replicates was set up, with each block containing two plots of the prepared substrate. In one of the plots, pig slurry was applied on the surface as a mulch to enhance infiltration and promote plant establishment. The quality of the newly created Technosols and the benefits of mulch application were evaluated 2 and 4 years after the rehabilitation. After two years, salt-tolerant plant species colonized the rehabilitated areas, providing sufficient vegetation cover to control water, soil, and nutrient losses, keeping soil losses below a 2.2 Mg ha⁻¹ yr⁻¹ threshold. Four years later, the new Technosols showed a fourfold increase in soluble organic-C content (up to 0.59 g kg⁻¹) and higher soil respiration rates compared to the mine spoils and lignite powder in the surrounding degraded quarry areas. No significant differences were observed in any parameters due to superficial slurry application. Addressing salinity and optimizing vegetation cover are crucial for the successful formation and sustainability of Technosols in these environments. Full article

This study focuses on the physiological response of lettuce grown on Technosols designed for the remediation of soils polluted by potentially harmful elements (PHEs: As, Cd, Cu, Fe, Pb, and Zn). Lettuce plants were grown in five treatments: recovered (RS) and polluted soil (PS) as controls, and three Technosols (TO, TS, and TV) consisting of 60% PS mixed with 2% iron sludge, 20% marble sludge, and 18% organic wastes (TO: composted olive waste, TS: composted sewage sludge, and TV: vermicompost of garden waste). The main soil properties and PHE solubility were measured, together with physiological parameters related to phytotoxicity in lettuce such as growth, photosynthetic capacity, oxidative stress, and antioxidant defence. All Technosols improved unfavourable conditions of PS (i.e., neutralised acidity and enhanced OC content), leading to a significant decrease in Cd, Cu, and Zn mobility. Nevertheless, TV was the most effective as the reduction in PHEs mobility was higher. Furthermore, lettuce grown on TV and TO showed higher growth (+90% and +41%) than PS, while no increase in TS. However, lower oxidative stress and impact on photosynthetic rate occurred in all Technosols compared to PS (+344% TV, +157% TO, and +194% TS). This physiological response of lettuce proves that PHE phytotoxicity is reduced by Technosols. Thus, this ecotechnology constitutes a potential solution for soil remediation, with effectiveness of Technosols depending largely on its components. Full article

In order to obtain solutions to the coal mining region demand in southern Brazil for high-performance and low-cost technosols within a concept of mineral circularity and sustainable development of the coal sector, this study aims to evaluate the functional feasibility of the combined use of a residual fraction of coal tailing, waste from the rice and poultry agro-industry, as well as the cellulose industry, as raw materials for technosol development. Characterizations (XRF, LOI, ICP-OES, pH, XRD, and sulfur forms) were performed to adjust the waste proportions used in the constructed soil, as defined based on the clay content of the coal tailing, the organic carbon content of the poultry litter, and technical recommendations for the use of synthetic gypsum in agricultural soils. Based on the characterizations of the residues, a greenhouse experiment was designed, consisting of four technosol formulations (T1–T4). Initially, an ecotoxicity test was conducted with the treatments in contact with Allium cepa L. (onion) to determine the degree of technosol toxicity. Field tests were then carried out, which were replicated three times in a completely randomized block design, with the germination and growth of Lactuca sativa L. (crisp lettuce) as a bioindicator. The fertility of the treatments was analyzed eight weeks after the establishment of the experiment and compared to standard values for agricultural soils. The characterization performed with the individual wastes demonstrated the potential for application in technosols according to current regulations. The ecotoxicity tests showed that the soil was not toxic to the plant in any of the treatments studied. The field experiment demonstrated no difference in germination between the treatments. However, the development of lettuce seedlings occurred only in technosol formulations T2 and T3, highlighting the potential of the studied residues for the construction of technosols. Full article

This study evaluated the effectiveness of six Technosols designed for the remediation of polluted soils (PS) by metal(loid)s at physicochemical, biological, and ecotoxicological levels and at a microcosm scale. Technosols T1–T6 were prepared by combining PS with a mix of organic and inorganic wastes from mining, urban, and agro-industrial activities. After two months of surface application of Technosols on polluted soils, we analysed the soil properties, metal(loid) concentration in total, soluble and bioavailable fractions, soil enzymatic activities, and the growth responses of Trifolium campestre and Lactuca sativa in both the Technosols and the underlying polluted soils. All Technosols improved the unfavourable conditions of polluted soils by neutralising acidity, increasing the OC, reducing the mobility of most metal(loid)s, and stimulating both the soil enzymatic activities and growths of T. campestre and L. sativa. The origin of organic waste used in the Technosols strongly conditioned the changes induced in the polluted soils; in this sense, the Technosols composed of pruning and gardening vermicompost (T3 and T6) showed greater reductions in toxicity and plant growth than the other Technosols composed with different organic wastes. Thus, these Technosols constitute a potential solution for the remediation of persistent polluted soils that should be applied in large-scale and long-term interventions to reinforce their feasibility as a cost-effective ecotechnology. Full article

The lack of topsoil is frequently a limiting factor in limestone quarry restoration. This implies that new technosols for maintaining target habitats must be created using mining wastes as the main components. We designed three different technosols using different combinations of mineral materials (mining wastes, excavated soils and topsoil), organic amendment types (compost and digestate) and doses for the restoration of target habitats. Moreover, we monitored the main physicochemical indicators of the quality of the technosols. We observed not only an increase in soil organic carbon and plant nutrients related to the application of any type of organic amendment, but that the digestate mostly increased the soil resistance to erosion by improving soil aggregation even before the emergence of vegetation. Soil-water-retention capacity only improved in technosols built with organic amendments and topsoil. The combination of mining wastes, organic amendments and a superficial horizon of topsoil resulted in the most optimal technosol for the restoration of limestone quarries in the Mediterranean climate. Full article

Reclamation of abandoned mining areas can be a potentially viable solution to tackle three major problems: waste mismanagement, environmental contamination, and growing food demand. This study aims to evaluate the rehabilitation of mining areas into agricultural production areas using integrated biotechnology and combining Technosols with a multipurpose (forage, food, ornamental and medicinal) drought-resistant legume, the Lablab purpureus (L.) Sweet. Two Technosols were prepared by combining gossan waste (GW) from an abandoned mining area with a mix of low-cost organic and inorganic materials. Before and after plant growth, several parameters were analysed, such as soil physicochemical characteristics, nutritional status, bioavailable concentrations of potentially hazardous elements (PHE), soil enzymatic activities, and development and accumulation of PHE in Lablab, among others. Both Technosols improved physicochemical conditions, nutritional status and microbiological activity, and reduced the bioavailability of most PHE (except As) of GW. Lablab thrived in both Technosols and showed PHE accumulation mainly in the roots, with PHE concentrations in the shoots that are safe for cattle and sheep consumption. Thus, this is a potential plant that, in conjunction with Technosols, constitutes a potential integrated biotechnology approach for the conversion of marginal lands, such as abandoned mining areas, into food-production areas. Full article

In this work the adsorption and immobilization of copper ions of four different Technosols constructed with wastes were tested. These soils were made from mixtures of limestone wastes, organic matter, sand, and bentonite. The methods used were “batch” and columns experiments, where the soils were in contact with a Copper (Cu) rich solution for 24 h and afterwards for 24-weeks. Total concentration of adsorbed Cu, sequential extraction in the Technosols and Cu concentration in the leachates were evaluated. The results showed that the Technosols have high efficiency to rapidly immobilize Cu ions, and the percentage of adsorption varied between 87 and 99% in the batch experiment after 24 h. The sequential extraction showed that the materials used in the construction of technosols demonstrated high affinity for the metal, especially the carbonates and organic matter, which adsorbed 14–16% and 10–16% respectively of total Cu added via solution. However, most of the adsorbed Cu was found in the residual fraction (50–64%), which represented the less labile form of Cu. These results demonstrate that in addition to adsorb great part of the Cu added via solution, the Technosols immobilize Cu in a highly stable form, representing a great option for the reclamation of contaminated-Cu areas. However, the decrease in pH with time (24 weeks) showed a strong influence on the adsorption of Cu in Technosols, influencing the amount of leached copper. We therefore recommend the design of Technosols with limestone wastes, bentonite, and organic matter with periodical control of pH for fast and efficient retention of Cu. Full article

A large number of heavy metals are usually contained in mine-derived liquids, which could cause contamination of surrounding water sources. Due to the detrimental effects on the environment and health, conventional treatments have been employed to capture heavy metals in mining-polluted streams. This study shows the results of the operation of a built prototype for the retention of arsenic contained in waters contaminated by mining activities using Technosols (mixtures of local soil with nanoparticles). Our team previously run laboratory tests using fixed-bed columns to find out the best dose of the Technosol (97% soil + 3% nanoparticles). Based on these results, the sizing and building of a scale model were conducted, which in turn was used to evaluate the performance of the treatment in a concrete channel packed with reactive barriers. Variations in water volume, barrier separation and gate opening were tested to analyze the behavior of the proposed system and to obtain the most optimal hydraulic retention time that allowed the prototype to reach an arsenic retention level of a minimum of 70%. Moreover, to analyze the procedure under conditions of high arsenic contamination, samples of mine tailings were enriched with the toxic metalloid. It was found that the content of Fe in the local soil allowed adsorption of the contaminant, which was subsequently compared with the increase in the uptake of As due to the Fe/FeS multicomponent nanoparticles (NPs), dosed in the Technosol in a proportion of 97% soil + 3% NPs. The best treatment achieved 70.5% of As removal in ten cycles with a volume of 44 L. Tests were run at a maximum input flow rate of 43.8 L·min⁻¹, an output flow rate of 13.2 L·min⁻¹, a speed of 6.0 m·min⁻¹ and a hydraulic retention time of 3.4 min per cycle. Results of arsenic retention using this prototype suggest that this simple and inexpensive technological setup could be scaled up to a functional field application to effectively capture the toxic metalloid. Full article

Soil is a non-renewable natural resource. However, the current rates of soil usage and degradation have led to a loss of soil for agriculture, habitats, biodiversity, and to ecosystems problems. Urban and former industrial areas suffer particularly of these problems, and compensation measures to restore environmental quality include the renaturation of dismissed areas, de-sealing of surfaces, or the building of green infrastructures. In this framework, the development of methodologies for the creation of soils designed to mimic natural soil and suitable for vegetation growth, known as constructed soils or technosols, are here reviewed. The possible design choices and the starting materials have been described, using a circular economy approach, i.e., preferring non-contaminated wastes to non-renewable resources. Technosols appear to be a good solution to the problems of land degradation and urban green if using recycled wastes or by-products, as they can be an alternative to the remediation of contaminated sites and to importing fertile agricultural soil. Nevertheless, waste use requires analysis to ensure the salubrity of the starting materials. Moreover, materials produced on site or nearby minimize the cost and the environmental impact of transport, thus the involvement of local stakeholders in the urban land management must be encouraged. Full article

Urban agriculture is sprouting throughout the world nowadays. New forms of urban agriculture are observed such as rooftop farming. In the case of low-tech rooftop farming projects, based on recycled urban waste, one of the key issues is the type of substrate used, as it determines the functions and ecosystem services delivered by the green roof. Using a five year experimental trial, we quantified the food production potential of Technosols created only with urban wastes (green waste compost, crushed wood, spent mushroom), as well as the soil fertility and the potential contamination of food products. Regarding food production, our cropping system showed promising results across the five years, in relation with the high fertility of the Technosols. This fertility was maintained, as well as the nutrients stocks after five cropping years. Most of the edible crops had trace metals contents below existing norms for toxic trace metals with nevertheless a concern regarding certain some trace metals such as Zn and Cu. There was no trace metal accumulation in the Technosols over time except for Zn. This study confirmed that constructing Technosols only from urban wastes is a suitable and efficient solution to design rooftops for edible production. Full article