Diego Arán

The management of organic waste in mining operations located in remote regions poses considerable logistical challenges, primarily because of the long distance to available landfill sites and the associated high costs. In addition, substantial environmental concerns arise from greenhouse gas emissions generated during waste processing and transportation. This study evaluated the implementation of an accelerated and automated composting process for the on-site treatment of organic waste at a mining operation. Operational performance indicators were established and evaluated over a 14-month period, including waste-to-compost conversion ratios, environmental indicators comparing emissions from conventional waste management with on-site treatment, and an economic profitability analysis. The quality of the produced compost was also assessed. The results showed an average conversion rate of 32 ± 7%, resulting in a 38% reduction in emissions compared with landfill disposal, equivalent to 0.17 kg CO₂e per kg of food waste treated. From an economic perspective, the process generated savings equivalent to USD 41.52 per Mg of food waste. Overall, the quality of the compost produced was adequate and met most regulatory and hygiene requirements. The comprehensive evaluation demonstrated that the improvements achieved by this management model offer an opportunity for treating organic waste in mining contexts and in communities with limited access, as well as under operational or environmental conditions that restrict conventional composting alternatives.

Wildfires are a dominant ecological disturbance in Mediterranean ecosystems, yet how post-fire aboveground carbon dynamics and vegetation characteristics govern soil organic carbon stock (SOC) remains poorly understood. This study characterized the dynamics of the carbon pool and changes in the plant community in cork oak shrublands in southern Portugal 11 and 19 years after a fire. Unburned stands were used as a reference. Five plots of each scenario were selected, for a total of 45 independent transects (15/scenario). Aboveground carbon, litter carbon, SOC, and community structural and diversity traits were quantified. Random Forest regression was used to identify the structural and compositional predictors at each stage. The results showed that 11 and 19 years after the fire, the stands held approximately 3:1 and 2:1 more aboveground carbon than the unburned sites due to higher post-fire shrub growth. Total litter carbon amount reached the highest value at 19 years, accompanied by a transient increase in species richness. However, SOC did not differ significantly across any scenario, revealing a clear decoupling between above- and belowground pools, likely constrained by Mediterranean drought conditions. Random Forest analysis showed that the nature of the vegetation–SOC relationships shifted qualitatively across the chronosequence, from structurally dominated in unburned stands to increasingly species-identity-driven. These findings highlight the limitations of assuming monotonic post-fire carbon recovery and underscore the role of species functional identity in mediating long-term SOC dynamics in Mediterranean shrublands.

The recovery of sulfide mine areas using designed Technosols and vegetation is often evaluated under controlled conditions, whereas field-scale evidence remains scarce. The first pilot (1.5 ha) with designed Technosols, produced from agro-industrial and urban wastes, was installed at the São Domingos mine (Iberian Pyrite Belt, Portugal)in two areas subject to continuous leaching of acid mine drainage, for environmental recovery purpose. An adjacent area without Technosol was used as control. The areas with and without Technosol were sown with a commercial herbaceous mixture including some autochthonous shrub species. After 4.5 years from recovery system (Technosol+vegetation) installation, the physicochemical quality of soil (pH, EC, fertility, nutrients and potentially hazardous elements-PHE availability) and the vegetation status (species composition, % cover, total biomass, seed bank diversity) were evaluated. A total of 25 randomly distributed sampling points were established with both soil and vegetation samples collected at each point (T1-Technosol area: 15, T2-Technosol area 2: 5, control: 5). The aim of the study was to evaluate the chemical quality of soil and vegetation status in the Technosol and control areas at long-term.The application of the designed Technosol significantly improved the soil quality of the mine area compared to the control, increasing pH (from 4.08 to 7.76) and organic C content (62.49 vs. 2.42 g kg⁻¹). The available fractions of macronutrients were higher in the Technosols areas while available PHE amounts were approximately 73% lower than in the control area. Vegetation reflected soil improvement, with 20 taxa (10 families) registered and higher family richness in the Technosol areas (10 vs. 4) .Technosols areas were dominated by Poaceae and Asteraceae showing almost complete soil cover (~96%). The control area was barely covered (

Abandoned mining sites are a major source of long-term soil contamination by potentially toxic elements. This study assessed the environmental risk of metal-contaminated soils from the Sidi Kamber mine (northeastern Algeria). Mining residues are spread into the surrounding areas and the Oued Es-Souk, a river that supplies the Guenitra dam.This dam is the main drinking water reserve in the Skikda region..This study is based on the geochemical and ecotoxicological analysis of 16 soil samples, from four stations distributed along the Oued Es-Souk until the dam. Samples were taken at two depths (0–25 cm and 25–50 cm) during both the dry and wet seasons. in Metal availability was evaluated through simulated leachate analyses, while soil properties (pH, fertility and pseudo-total elemental concentrations) were determined using conventional methods. Ecotoxicological bioassays were conducted to assess the biological effects of both soils and leachates in two plant species (Allium cepa and Lactuca sativa), focusing on seed germination, root elongation, and total biomass production as sensitive indicators of phytotoxicity. Soil pollution indices, including the Igeo-Geoaccumulation Index and the CF-Contamination Factor were calculated to quantify contamination levels and identify the most critical elements.The soils showed a very variable conductivity (510–3460 μS/cm) and a pH ranging from neutral to slight acid (5.15–7.54), with a tendency towards acidification during dry season. The leachates, less saline, were systematically acid (pH ~5). The organic carbon and some available nutrients contents were relatively low confirming low soil fertility.The upstream location had the lowest Zn, Mn, Cu, and Pb concentrations in pseudo-total fraction recorded in wet season (194, 480, 16.5, and 88 mg/kg, respectively). Despite being the lowest on the site, these levels exceeded benchmarks reported by Dutch Target Values or AFNOR standards. The highest concentrations are located at the surface of the soils and at specific points, reflecting a localized accumulation. Mobility Index (MI = Av/PT) ranked metals in descending order of mobility: Cd>Zn>Ni>Cu>Pb>Cr>Fe. Contamination Factors confirm a significant polluting heritage: the pseudo-total contents of Zn, Pb and Cd are considerably enriched (CF>10 in many cases) compared to local natural levels. The geoaccumulation index classifies metals into three categories: strong to extreme contamination for Cd and Pb (Igeo>3); moderate accumulation for Zn and S (1

Pyrolysis-derived products are increasingly being researched to improve soil and manage organic by-products from agroforestry and livestock operations. However, their chemical behavior and agronomic safety vary with feedstock and pyrolysis conditions. Eucalyptus bark contains phenolic and tannin compounds with allelopathic effects, while sheep wool contains nitrogen and sulfur compounds, which, at low pyrolysis temperatures, may produce ecotoxic substances. In soil solution, these compounds may reduce seed germination and plant growth. Therefore, assessing the ecotoxicology of leachates from pyrolysis-derived products is important to ensure the safe agricultural use of products from a circular economy.This study assessed the ecotoxicology of leachates from pyrolysis-derived products using bioassays with two sensitive plant species. Pyrolysis-derived products included Eucalyptus bark (EB), sheep wool residues (SWR), and mixed EB/SWR at various ratios (100% EB, 100% SWR, 30/70, 40/60, 60/40, and 70/30). Feedstocks were pyrolyzed at various temperatures (150 to 500 °C) and residence times (10, 20, and 30 minutes). Simulated leachates (DIN extraction) were obtained from the raw eucalyptus biomass (EM) and pyrolysis-derived products and used in a bioassay (filter paper, n=5 replicates/treatment, n=25 seeds/replicate) with Lactuca sativa and Allium cepa..The bioassays were carried out in a growth chamber maintained at a temperature of 25 ± 1 °C and a photoperiod of 16 h light and 8 h dark. The leachates were characterized by the elemental analyses of the macronutrients (K, Ca, Mg, P, and Na) and the ecotoxicity was determined by the measuring the percentage of germination, the time to 50% germination (T₅₀), the total dry biomass, as well as the total dry plant biomass and roots and shoots elongations. The statistics were conducted using ANOVA and the means were separated using Dunan’s multiple range test for the means which were significantly different at a 5% level (p ≤ 0.05).The leachates presented differences in their chemical characteristics. Higher pyrolysis temperatures result in leachates with a higher pH and greater concentrations of Ca, Mg, and K. Conversely, leachates from unprocessed eucalyptus biomass and low-temperature pyrolysis products exhibited higher electrical conductivities and concentrations of elements. The final germination percentages were relatively similar across all treatments for both species, indicating a relatively robust germination response to a broad range of chemical characteristics of the leachates The remaining plant parameters were more sensitive to the treatment effects. Low-temperature pyrolysis treatments contributed to the reduction of root elongation and total dry biomass. On the other hand, leachates from pyrolysis-derived products obtained at temperatures greater than or equal to 400 °C positively influenced overall seedling performance, particularly the mixtures of eucalyptus bark and sheep wool. Pyrolysis temperature played a vital role in determining leachate quality and potential ecotoxicity. The products of high-temperature pyrolysis (≥400 °C) produced leachates with lower ecotoxicity and, in some instances, positive effects on early seedling development. Conversely, unprocessed biomass and low-temperature pyrolysis products contained leachate constituents capable of inducing unfavorable physiological responses in sensitive plants.Keywords: Simulated Leachates, Bioassay; Pyrolysis; Lettuce; Onion; sheep wool wastes

Agriculture in semi-arid Mediterranean regions contributes significantly to local food production and rural livelihood. Nevertheless, it depends strongly on irrigation to sustain crop production and soil fertility. With the terrain complexity present, irrigation can lead to downward and lateral transfer of soil particles and nutrients, thus intensifying and accelerating the complex interplay between leaching and erosion, which in turn, reduce soil productivity and create spatial fertility imbalances. This study addresses the lack of knowledge about these processes to support better soil management in Bir Bouhouch irrigated perimeter with complex terrain characteristics in northeastern Algeria , which represents a strategic agricultural area mainly producing cereals .The area has been used for intensive agriculture since the expansion of irrigation schemes in recent decades .In This study the vertical and catenary variability of physicochemical characteristics of soils were examined. Four soil profiles along a toposequence from the summit (P1), to the toeslope (P4) were described and soils samples were collected in different depth to physicochemical characterization (texture, pH and electrical conductivity in water (EC), active lime, organic matter (OM), total nitrogen and extractable phosphorus. All profiles showed alkaline pH (8.10–8.60) with low EC (0.23–0.58 dS/m) that increased progressively from the summit to the teslope as well as with depth. Surface horizons (0- 60 cm) at downslope profiles showed finer textures with transition from silty clay to loamy clay and higher OM contents (up to 17.2 g/kg) compared with the summit (9.00 g/kg), indicating possible downslope colluvial accumulation. Active lime increased but followed a bi-profile sequence along surface (from 55 to 145 g/kg for P1-P2 and from 35 to 105 g/kg for P3-P4) and with depth reflecting a possible carbonate leaching and re-precipitation under alkaline conditions, locally forming caliche horizons. Extractable P concentrations ranged from 0.05 to 0.07 mg/kg and were enriched at lower slope positions at surface horizons. Besides total N (0.8–1.5 g/kg) showed limited vertical and lateral variation. These patterns demonstrate that soil variability along the transect can be mainly controlled by the topography-driven redistribution and carbonate dynamics enhanced by irrigation.This work was funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projects UIDB/04129/2020 and UID/04129/2025 (LEAF) and LA/P/0092/2020 (TERRA).

Abandoned ore processing plants represent critical, long-term sources of environmental contamination and therefore constitute an important field of research for the subsequent rehabilitation of the area. The objective of this study was the evaluation of the level and spreading of soil contamination by trace metal elements in the vicinity of an abandoned ore processing plant in northeastern Algeria. Superficial soil samples were collected from 8 sampling stations located upstream, downstream, and directly at the abandoned ore processing plant during the wet and dry seasons. An environmental assessment of soil samples was conducted through the analysis of physicochemical characteristics: pH, electrical conductivity, and concentration of nutrients and potentially toxic elements in the available and total fractions.Soil samples showed marked spatial variability in pH values and electrical conductivities although, in general, soils collected in the both seasons showed an acid pH (3.66-4.19) and low-moderate EC (250-446 µS/cm)The total concentrations of S, Fe, Cr, As, Cu, Pb and Zn were elevated in all soil samples, exceeding the maximum values permitted for industrial land use according to soil legislation in several countries (e.g. Canada). For Ni and Cd, only some soil samples exceeded the maximum allowed values. The variation in the elements' availability revealed clear spatial heterogeneity between locations upstream and downstream of the abandoned ore processing plant. However, values remained consistently high near the plant regardless of position, which confirmed its role as the primary contamination source through multidirectional dispersion via runoff and wind.This work was funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the projects UIDB/04129/2020 and UID/04129/2025 of LEAF-Linking Landscape, Environment, Agriculture and Food, Research Unit and LA/P/0092/2020 of Associate Laboratory TERRA

Land degradation is a major environmental challenge in post-mining landscapes, where soil structure, fertility, carbon storage and potentially hazardous elements availability are severely compromised. Designed Technosols have emerged as a promising strategy for restoring soil functionality in such disturbed areas under different climatic conditions. Their effectiveness under field conditions over time requires systematic evaluation but these studies are scarce. A study was conducted at the São Domingos mine (Iberian Pyrite Belt, Portugal), where the first pilot project using designed Technosols for environmental rehabilitation was implemented in late 2020 (1.5 ha).From the rehabilitation implementation system, physicochemical characteristics of Technosol and vegetation development have been monitored to understand the underlying temporal dynamics. Additionally, to physicochemical analysis in the soil samples collected periodically, the evolution of the temporal change was assessed via remote sensing for the area. Adjacent areas without Technosol application were used as control.In general, mine areas without Technosol maintain their high environmental risk due to acid characteristics and high availability of potentially hazardous elements-PHE. Technosol remains their eutrophic and alkaline properties, supporting dense vegetation cover and improvement chemical characteristics of the area (pH, fertility and diminution of PHE spreading). Nonetheless temporal patterns following Technosol application have been observed.For instance, Organic C and total N exhibited similar trends, with the highest values at implementation (130.58 g/kg and 7.92 g/kg, respectively), followed by a moderate decline over time, although it was statistically significant only after six months. C stock dynamics further supported these trends. Below-ground C stock increased gradually from (96.65 to 106.81 t C/ha) over 27 months and remained within the same overall range as the implementation, indicating high stabilization potential. Overall, Above-ground C stock increased from 11.55 to 108.85 t C/ha, peaking at 302.31 t C/ha after six months. Temporal evaluation using NDVI showed an increase in area and intensity of the index from 0.03 to 0.9. Overall, the grouped trends demonstrate that Technosols simultaneously promote biological activity, the improvement of C and N balance and enhance both below- and above-ground C stocks.To evaluate the drivers of the rehabilitation system evolution, remote sensing products to derive topographic and hydrologic covariates (slope, aspect, topographic position, and connectivity proxies) are included to evaluate their influence on C stock, PHE availability and runoff connectivity in adjacent areas to the Technosol area. This study provides important indicators framework linking contamination dynamics and ecosystem recovery as well as the effectiveness of the environmental system with designed Technosol at long term.This work was funded by national funds through FCT—Fundação para a Ciência e a Tecnologia under the projects UID/04129/2025 (LEAF) and LA/P/0092/2020 (TERRA).

Propose: Sustainable agriculture promotes the use of local resources for management and production without diminishing crop profitability. This represents a challenge in the search for new products with lower environmental impact and fertilizer alternatives that meet the nutritional needs of crops. The objective of this study was to develop a tailored amendment, formulated and produced from recovered waste, and to evaluate its effectiveness in meeting the specific needs of the soil and the Vitis vinifera var. Red Globe crop. Methods: The amendment was formulated from agro-industrial waste (asparagus residue, four different types of bagasse, cattle manure, and ash) sourced within a 150-km radius from the production facility. Its response in a vineyard —1 ha per treatment— was compared against a mix of cattle and sheep manure (conventional amendment). Quality assessment was performed based on the soil’s physicochemical characteristics during the 615 days after application, and its response to the crop during the first year, using growth and productivity variables. Economic performance was assessed through a cost–benefit comparison of the two amendments transportation, production, application and product sells. Results: The soil fertilized with the designed amendment showed improved nutritional status, with increased organic matter, nitrogen, and cation exchange capacity compared to both the control and pre-fertilization conditions. Vine growth and productivity parameters showed a significant increase in branch length, yield, bunch count per plant, and bunch weight, resulting in an increase of more than 9 Mg of grapes/ha with the designed amendment compared to the conventional one. Economic evaluation revealed a net gain exceeding USD 18,500 per hectare when using the designed amendment instead of the conventional manure, therefore the financial analysis also showed the opportunity for scaling it up in the sector. Conclusion: The designed amendments based on the valorization of agro-industrial waste proved to be an appropriate solution for vineyard fertilization, contributing to improved its productivity and soil quality.

This study examined long-term changes in soil carbon stock dynamics 11 and 19 years after fire under different severities at 0–5 and 0–25 cm depths with a digital soil mapping approach. Linear (MLR) and non-linear models (RF, SVR, XGBoost) combined with feature selection methods (r < 0.8, FFS, Boruta) were used to predict bulk density (BD), total C, and C stock. Distributional biases were evaluated with Kolmogorov–Smirnov statistics and corrected by Quantile Mapping (QM). RF-FFS performed best for BD and total C at 0–5, while RF-SVR outperformed for C stock and all properties at 0–25. Total C was 49% higher at 0–5, whereas C stock was 7.57 times greater at 0–25. Both models underestimated variability, especially for C stock. At 0–25, bulk density decreased after fire, particularly under conditions of medium severity, while total C increased following the same tendency. The results showed that fire’s legacy is still present in the ecosystem after one and two decades. This is particularly evident at greater depths, where long-term C stock is lower.