JWSS - Journal of Water and Soil Science

Biochar, a stable, economical, and environmentally friendly carbonaceous material, has garnered significant attention in the development of advanced adsorbents for the immobilization and removal of environmental pollutants from water and soil. This interest stems from its oxygen-containing functional groups, aromatic structure, notable porosity, high specific surface area, and suitable cation exchange capacity. However, the performance limitations of pristine biochar in pollutant removal underscore the necessity for its modification and engineering. In this regard, the production of biochar composites through the combination with minerals and iron-containing compounds has emerged as an effective strategy to enhance structural and chemical properties, as well as surface reactivity. This review paper examines the primary methods for synthesizing biochar composites, including post-pyrolysis modification and direct mixing with mineral phases. Synergistic and direct loading methods are introduced as novel approaches. Furthermore, the influence of biomass type, pyrolysis conditions, modifier type, and synthesis pathway on the final physicochemical characteristics of the composites is analyzed. Additionally, the governing mechanisms underlying the performance of these materials in immobilizing and removing heavy metals are discussed, encompassing adsorption, precipitation, complexation, ligand exchange, redox reactions, electron transfer, electrostatic interactions, and ion exchange. Study results indicate that the synergy between biochar and mineral/iron-bearing phases can significantly enhance the efficiency of immobilizing pollutants, including both anionic and cationic heavy metals. This review emphasizes the importance of targeted design of biochar composites based on a precise understanding of the relationship between synthesis methods and functional properties. Future challenges and prospects concerning the application of biochar-mineral composites in environmental remediation and the promising commercialization of this technology are also addressed.

Excessive groundwater abstraction is a major environmental and economic challenge in Iran’s arid and semi-arid regions. This study examined farmers’ perceptions of groundwater over-abstraction and its perceived socioeconomic consequences in the Siminehroud catchment. Data from 373 questionnaires were analyzed using descriptive statistics, Mann–Whitney U tests, and chi-square tests. Effect sizes were reported, and p-values were adjusted using the Benjamini–Hochberg procedure. Overall, 41.8% of respondents believed that groundwater over-abstraction was occurring in their locality. Respondents with this perception were younger (median 48.5 versus 53 years; p<0.001), and the proportion with this perception was lower among users of piped water conveyance than among users of traditional canals (24.2% versus 45.6%; p=0.001). Both associations remained significant after false-discovery-rate adjustment. The most frequently perceived consequences of groundwater-level decline were declining farm income, loss of irrigated land, changes in cropping patterns, and increased migration. The findings indicate that groundwater management in Siminehroud should incorporate aquifer monitoring, improved water conveyance, and social interventions tailored to users’ characteristics.
 

This study evaluated groundwater-level variations in the Isfahan-Borkhar aquifer and examined their relationship to land subsidence. Representative hydrographs, groundwater-level maps, depth-distribution maps for the wettest and driest months of the study period, and a 20-year groundwater-level variation map were prepared and compared with the land subsidence map within the aquifer area. The results indicated that subsidence zones were mainly located in areas experiencing considerable groundwater-level decline. The occurrence of critical subsidence zones in regions with a high density of pumping wells and agricultural lands further confirmed this relationship. In addition, the alluvial-thickness map of the study area was prepared and compared with the land subsidence map to investigate the relationship between the spatial distribution of subsidence zones and alluvial thickness. The findings indicated that land subsidence is associated not only with groundwater-level decline but also with other factors, including alluvial thickness and soil texture. In other words, even under substantial groundwater-level decline, significant land subsidence is unlikely where alluvial thickness and the proportion of compressible fine-grained sediments are low.

 

Nickel (Ni) is an essential element for living organisms and plays important biological roles in plants; however, its accumulation at high concentrations can cause toxicity and adverse effects. This study aimed to evaluate nickel accumulation using the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus as biological indicators in Ahvaz City during the summer of 2025. A total of 126 leaf samples and 63 soil samples were collected from seven stations across Ahvaz City. Chemical digestion of the leaf and soil samples was performed using the Johnson and EPA 3050 methods, respectively. Nickel concentrations were determined using atomic absorption spectrometry. Significant differences were observed in Ni concentrations among the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus (P < 0.05), whereas no significant difference was observed in Ni concentrations among the soil samples (P > 0.05). The highest and lowest Ni concentrations in the unwashed and washed leaves of Albizia lebbeck were 36.2 and 10.3 mg kg⁻¹, respectively. The highest and lowest Ni concentrations in the soil samples collected from the tree rhizospheres were 57.36 and 44.1 mg kg⁻¹, respectively. The highest Ni transfer factor was observed in Albizia lebbeck leaves (0.446), whereas the lowest was observed in Eucalyptus globulus leaves (0.203). The Ni transfer factors for the leaves of Albizia lebbeck, Prosopis cineraria, and Eucalyptus globulus, together with the linear regression analysis of Ni concentrations in washed and unwashed leaves, indicate that atmospheric deposition may be an important source of Ni accumulation in the leaves. In contrast, the contribution of soil-derived Ni to leaf accumulation appears to be relatively low.

This research was conducted with the aim of site selection and land capability evaluation for the development of pistachio cultivation in Sistan and Baluchestan province by integrating Geographic Information Systems (GIS), the Analytical Hierarchy Process (AHP), and remote sensing data (Landsat 8 satellite imagery within the Google Earth Engine platform). Eight criteria, including distance from water canals, roads, and population centers, land use, slope, elevation, slope aspect, and soil characteristics (salinity, texture, and pH), were weighted based on the opinions of 15 experts (inconsistency ratio = 0.03). The highest weights were assigned to distance from water canals (0.32), soil characteristics (0.25), and distance from roads (0.14). Information layers with a spatial resolution of 30 m were prepared in the GIS environment and integrated using the weighted overlay method. The final map showed that 13.8 percent of the province is in the highly suitable class, 23.0 percent in the moderately suitable class, 33.5 percent in the marginally suitable class, 27.5 percent in the unsuitable class, and 2.2 percent has absolute limitations. The findings indicated that 36.8 percent of the province has significant potential for the development of pistachio cultivation; however, the main limitation is access to water resources. 65.5 percent of the province is located in the unsuitable category in terms of distance from water canals. Therefore, the sustainable development of pistachio cultivation in the province requires precise planning with a focus on suitable areas and the sustainable management of water resources. The novelty of this research lies in applying Boolean masks to eliminate ecological errors and using cloud computing (GEE) for the temporal consistency of data. Furthermore, comparative analysis revealed that crop development in some areas (such as Zahedan) relies more on groundwater extraction than on inherent land potential; the model classifies these areas as "unsuitable," providing a preventive warning regarding long-term sustainability

The Helmand River is the main source of water for the Sistan Plain and underpins the provision of key ecosystem services, including water supply, agricultural production, forage provision, soil protection, and wildlife habitat. The operation of the Kamal Khan Dam and the diversion of river flow toward Goud-e Zereh have reduced downstream water availability and accelerated land degradation in Sistan. This study aimed to assess land-use and land-cover changes associated with Helmand River water availability before and after the operation of the dam. Land-use/land-cover maps for 2019, 2020, 2024, 2025, and 2026 were produced using Landsat imagery, supervised classification, and the Random Forest algorithm, and their accuracy was evaluated using field-based reference samples. The results showed that, after dam operation, the Hamoun-e Hirmand water body completely dried up, whereas the water-covered area around Kamal Khan Dam and in the Goud-e Zereh region increased from 3,039 ha in 2019 to 62,794 ha in 2026. In the Sistan Plain, agricultural land reached its maximum extent of 69,025 ha in 2020 but declined to 5,776 ha in 2025. In addition, the area of saline lands in the Sistan Plain and Hamoun increased from a minimum of 110,414 ha in 2020 to a maximum of 274,708 ha in 2026. These changes were accompanied by a reduction in rangelands, an expansion of barren lands, increased soil salinity, and greater soil susceptibility to wind erosion. The findings indicate that the diversion of water toward Goud-e Zereh, together with associated declines in agricultural land, rangelands, and soil moisture and the expansion of saline and barren lands, has weakened the ecosystem services provided by the Helmand River.
 

Managed Aquifer Recharge (MAR) using treated wastewater is a viable strategy for water-resource sustainability in arid regions; however, the simultaneous assessment of its hydrogeological and economic aspects remains challenging. The objective of this study was to hydro-economically evaluate the implementation of an MAR project in the Qotb-Abad Plain by integrating numerical modeling and cost-benefit analysis (CBA). The quantitative and qualitative responses of the aquifer were simulated using the MODFLOW and MT3DMS models to estimate changes in groundwater levels, nitrate concentrations, and total dissolved solids (TDS). Economic benefits, including pumping energy savings, the value of stored water, and improvements in water quality, were evaluated alongside capital and operational costs under lower- and upper-bound scenarios. Subsequently, economic indicators, including net present value (NPV), benefit-cost ratio (BCR), internal rate of return (IRR), and payback period, were calculated. The results indicated that implementing MAR with an annual treated wastewater volume of 1.898 million m³ resulted in an approximately 4.5 m rise in groundwater level, accompanied by reductions in TDS from 1859 to 1752 mg/L and in nitrate concentration from 22.2 to 15.4 mg/L by the end of the five-year simulation period. Under the upper-bound scenario, the NPV, BCR, and payback period were 43.7 billion Rials, 1.36, and 3.23 years, respectively. In contrast, the lower-bound scenario was not economically justified, as its BCR was less than 1. Overall, integrating numerical modeling with cost-benefit analysis provides a comprehensive framework for supporting groundwater-management decision-making.