In this study, we investigated the effect of different rates of compost (20%, 40%, 60% w/w) in combination with biochar (0%, 2%, 6% w/w) on soil physiochemical properties and the mobility of arsenic (As) and lead (Pb), in addition to the ability of Arabidopsis thaliana (ecotype Columbia-0) to grow and accumulate metal(loid)s. All modalities improved pH and electrical conductivity, stabilized Pb and mobilized As, but only the mixture of 20% compost and 6% biochar improved plant growth. Plants in all modalities showed a significant reduction in root and shoot Pb concentrations compared to the non-amended technosol. In contrast, As shoot concentration was significantly lower for plants in all modalities (except with 20% compost only) compared to non-amended technosol. For root As, plants in all modalities showed a significant reduction except for the mixture of 20% compost and 6% biochar. Overall, our results indicate that the mixture of 20% compost with 6% biochar emerged as the optimum combination for improving plant growth and As uptake, making it the possible optimum combination for enhancing the efficiency of land reclamation strategies. These findings provide a foundation for further research on the long-term effects and potential applications of the compost-biochar combination in improving soil quality.

Phytoremediation strategies present promising approaches for mitigating metal contamination in soils. This study examines the effectiveness of compost and biochar amendments, applied separately or in combination, in altering the properties of sandy mining waste soils (Sw) and affecting levels of metallic trace elements (MTEs). The research evaluates changes in soil physicochemical parameters, metal concentrations in soil pore water (SPW), and metal accumulation in Phaseolus vulgaris. Compost and biochar addition significantly affected SPW pH, which remained alkaline, while increasing SPW electrical conductivity (EC). A treatment combining 20% compost and 2% biochar (SwC20B2) enhanced soil enzymatic activities, with the highest values observed for FDA and ALP activities. Metal availability in the SPW appeared higher on D(0) compared to D(12), with notable reductions in Pb and Zn concentrations observed in the SwC20B2 treatment. Despite this decline, metal accumulation in plant shoots did not significantly differ from that in plants grown in unamended Sw, although all plants exhibited substantial growth. The minor decrease in SPW pH, likely due to compost, may have enhanced metal mobility at D(0). Notably, SPW Pb and Zn concentrations increased with higher compost rates, with SwC20B2 registering the highest Pb and Zn. Although these amendments did not directly alleviate metal mobility, they show potential for use in phytostabilization strategies by using suitable plant species.

Mining activities produce waste materials and effluents with very high metal concentrations that can negatively impact ecosystems and human health. Consequently, data on soil and plant metal levels are crucial for evaluating pollution severity and formulating soil reclamation strategies, such as phytoremediation. Our research focused on soils and vegetation of a highly contaminated site with potentially toxic metals (Pb, Zn, and Cu) in the Touissit mining districts of eastern Morocco. Vegetation inventory was carried out in three mine tailings of the Touissit mine fields using the “field tower” technique. Here, 91 species belonging to 23 families were inventoried: the most represented families were Poaceae and Asteraceae, and the biological spectrum indicated a predominance of Therophytes (55.12%). From the studied areas, 15 species were selected and collected in triplicate on the tailings and sampled with their corresponding rhizospheric soils, and analyzed for Pb, Zn, and Cu concentrations. Reseda lutea, lotus marocanus, and lotus corniculatus can be considered as hyperaccumulators of Pb, as these plants accumulated more than 1000 mg·kg⁻¹ in their aerial parts. According to TF, these plant species could serve as effective plants for Pb phytoextraction.

The extensive use of copper (Cu) in viticulture has resulted in its high accumulation in soils, threatening ecosystems and soil health. Biochar, widely recognized for its potential in remediating metal-contaminated environments, offers promising sorption properties that strongly rely on both feedstock composition and the final biochar’s characteristics. This study investigates five biochars produced from different vineyard by-products; grape marc (BM), grape seed (BS), exhausted grape seed (BES), pruning (BP1), and pruning subjected to double pyrolysis (BP2). These biochars were comprehensively characterized in terms of physicochemical and structural properties, elemental composition, and potential toxicity. The maximum copper sorption capacities of the biochars ranged from Q _max of 39.35 to 134.36 mg Cu ² ⁺g ⁻¹ , depending on their properties, and followed the Langmuir isotherm and pseudo-second-order (PSO) kinetic models (for BM). Fourier-transform infrared spectroscopy (FT-IR) confirmed the presence of surface functional groups such as –OH, –COOH, and aromatic structures. Zeta potential (ZP) analysis indicated a predominantly negative surface charge across a wide pH range. Copper sorption was primarily attributed to π-cation interaction and precipitation mechanisms, while copper desorption assays revealed limited copper release, suggesting strong retention. Scanning electron microscopy (SEM), coupled with energy-dispersive X-ray spectroscopy (EDS), was used to analyze the morphology of the biochar and to verify copper incorporation in the Cu-loaded samples. Given the strong influence of feedstock on metal sorption efficiency, vineyard by-products were characterized by thermogravimetric analysis (TGA), FT-IR, and determination of lignocellulosic composition and physicochemical properties. Biochar from vineyard by-products, particularly grape marc (BM), demonstrated the highest potential, highlighting the valorization of vineyard by-products as a sustainable in situ remediation strategy in vineyard soils, in line with circular economy principles.

Growing concerns over metal pollution highlight the need for effective remediation strategies. This study evaluates the accumulation capacity and tolerance of Melia azedarach and Ailanthus altissima for trace elements (Pb, Zn, and Cu), aiming to assess their phytoremediation potential. Three-month-old seedlings of both species, grown from seeds collected at the Touissit mine site, were cultivated in perlite and irrigated with Hoagland nutrient solution. Plants were exposed to various concentrations of metal salts—Pb(NO₃)₂ (8, 40, and 80 mg.L⁻¹), ZnSO₄ (8, 40, and 80 mg.L⁻¹), and CuSO₄ (2, 10, and 20 mg.L⁻¹)—over a 90-day period. Growth, biomass, metal accumulation, chlorophyll, and carotenoid contents were measured. Results indicate that M. azedarach exhibited enhanced biomass under Pb exposure, suggesting notable tolerance and potential for phytoremediation. Conversely, A. altissima showed an initial increase in biomass at low Pb levels, followed by a significant reduction at higher concentrations. Both species demonstrated decreased biomass under Zn and Cu treatments, with varying degrees of sensitivity. Notably, A. altissima accumulated significant levels of Pb, Zn, and Cu, particularly in the roots, indicating high phytoremediation potential. While M. azedarach also accumulated metals, levels were comparatively lower. Both species maintained chlorophyll content under metal stress, indicating resilience. Overall, this hydroponic screening highlights the considerable capacities of M. azedarach and A. altissima for Pb, Zn, and Cu tolerance, with A. altissima showing particularly high potential for Pb phytostabilization.