Ghasem Rahimi

Heavy metal contamination, particularly lead (Pb), poses significant risks to agricultural soil health and food safety. This study investigates Pb contamination in the Bahar plain, a key agricultural region in Iran, by integrating Sentinel-2 satellite imagery with some ground-based soil sampling and laboratory analysis. Forty topsoil samples were collected systematically and analyzed for Pb content, physicochemical properties, and spatial distribution relative to a major roadway. A predictive model was developed using spectral indices (e.g., Soil Adjusted Vegetation Index, and Weighted Difference Vegetation Index) and multivariate regression to estimate Pb levels from satellite data, achieving a strong Pearson correlation (r = 0.79) between lab-measured and model-predicted values. Results indicated that total Pb contents (15.17–42.62 mg/kg) were within permissible limits for calcareous soils, except near urban-industrial zones. Contrary to expectations, Pb levels increased with distance from the road, likely due to decades of chemical fertilizer use in central farmlands. The study demonstrates the efficacy of combining remote sensing and limited ground data for large-scale Pb monitoring, providing a framework for sustainable soil management and contamination risk mitigation.

Heavy metal pollution is considered a serious risk to the environment and human health due to its toxicity and indestructibility. Measuring and monitoring little concentration (even lower than the detection limit of the device) in the case of dangerous and biostable pollutants such as cadmium in natural water samples is a necessity. ...

Heavy metal contamination in soils presents a critical environmental challenge, threatening ecosystems, agricultural productivity, and human health. Conventional remediation techniques, such as biochar application, are limited by hydrophobicity, particle aggregation, and inefficient soil interaction. This study introduces a novel, sustainable adsorbent for heavy metal immobilization: carbon quantum dots (CQDs) loaded onto cyanobacteria-derived microcarriers. CQDs, with their high surface area, hydrophilicity, and abundant functional groups, offer superior adsorption potential. However, their direct use is hindered by mobility and separation challenges. To address this, cyanobacteria—rich in extracellular polymeric substances (EPS)—are utilized as dual precursors for CQD synthesis and microcarrier fabrication via the oilothermal pyrolysis method. This innovative technique employs an oil medium to prevent EPS dissolution during pyrolysis, enabling simultaneous carbonization of cyanobacterial cells and EPS into stable, spherical CQD-microcarrier composites. The resulting adsorbent combines the high adsorption capacity of CQDs with the structural advantages of microcarriers, ensuring uniform soil distribution, resistance to microbial degradation, and ease of separation. Experimental results demonstrate exceptional efficacy in immobilizing cadmium, with adsorption capacities exceeding traditional biochar by 40–60%, attributed to the composite’s hydrophilic functional groups (e.g., -OH, -COOH) and enhanced soil contact. The oilothermal method eliminates the need for costly precursors or hazardous equipment, offering a scalable, cost-effective, and eco-friendly solution. By integrating cyanobacteria cultivation, waste valorization, and one-step synthesis, this approach advances in-situ soil remediation, overcoming the limitations of existing technologies. The study underscores the potential of bio-based nanomaterials in sustainable environmental management, providing a blueprint for efficient, low-cost heavy metal mitigation while aligning with circular economy principles.

Soil contamination by anthropogenic heavy metals has become a global issue. This study aimed to investigate cadmium (Cd) concentration, mobility, and contamination indices of Cd in soils in the Hamadan province, west of Iran. To investigate the concentration of Cd in soil, one hundred soil samples from wheat farms and five samples from control lands were collected. Pollution indexes, including Cd mobility, enrichment factor, geoaccumulation index, contamination index, and availability ratio, were investigated. The structural equation model was also used to evaluate effective parameters on cadmium durability in soil. Results showed that mean values of available phosphorus (P) were 83.65, 129, and 65 (mg kg⁻¹) in three land-use types rainfed, irrigated, and controlled, respectively. The mean values of Cd in different land-use types of rainfed, irrigated, and controlled were 0.15, 0.18, and 0.08 (mg kg⁻¹), respectively. The results indicated that the amount of Cd in both forms (available and total) in ones that received fertilizer, especially P fertilizers, was higher than in the controlled one. Other pollution indexes revealed that the study area had been slightly contaminated due to anthropogenic activities. Lime, clay, lead, and OM were identified as affective parameters on cadmium durability. Finally, the results demonstrated that the mobility rate was high. Cd had a higher potential mobility in soil samples in the rain-fed and irrigated land than in the controlled land, and Cd had a low retention time.

We investigated the potential application of potato peel biochar (PPB) for the adsorption and immobilization of heavy metals (Cd, Pb, and Ni) in contaminated acidic soil. The addition of PPB to the soil, especially at the application rate of 8%, increased soil pH, cation exchange capacity (CEC), and organic carbon (OC). The maximum adsorption capacity of Cd, Pb, and Ni in the soil amended with PPB at the application rate of 8% was 3215.9, 4418.67, and 3508.51 mg kg⁻¹, respectively. Compared to the control, the addition of 8% PPB to the soil decreased the soluble and exchangeable fraction of Cd, Pb, and Ni to 84.3, 90.6, and 79.1 mg kg⁻¹, respectively. In contrast, the addition of 8% PPB to the soil increased the organically-bound and residual fractions of metals in the following order: Pb > Cd > Ni, and Cd > Pb > Ni, respectively. The results of this study showed that potato peel biochar has the potential to stabilize and reduce the bioavailability of heavy metals in contaminated acidic soil. Therefore, potato peel biochar can serve as an eco-friendly, low-cost, and efficient adsorbent to immobilization of heavy metals in contaminated acidic soils.

Irrigation with wastewater is possible in many arid and semi-arid countries that suffering from water shortage. Furthermore, addition of gypsum (CaSO₄. 2H₂O) to soil may be reduce effluent problems. This research targeted the consequences of gypsum and wastewater on soil properties, yield components, and element content in soils and Black cumin (Nigella sativa L.) seeds. Factorial and completely randomized designs were conducted at the research station of Avicenna herb garden. The results showed that gypsum (0, 3.48, 4.34, and 5.21 g kg^–1) and treated wastewater (0, 25, 50, 75, 100%), significantly affected soil heavy metal content. The highest concentrations of heavy metals found in the soil were iron (Fe), and the lowest copper (Cu) but, their values were below the critical level. The highest concentration of heavy metal in black cumin was iron found in the roots and stems, and the lowest was copper in the same plant parts. Generally, gypsum at the rate of 5.21 gkg⁻¹ and the irrigation with 75% concentration of effluent, increased significantly the plant yield components and heavy metals concentration in different black cumin organs. Still, the concentrations of all heavy metals studied were found within the standard limits.

Cadmium (Cd) is one of the toxic elements entering the food chain in various ways, including chemical fertilizers. This study aimed to assess different amounts and forms of available Cd in soils under wheat cultivation affected by long-term use of phosphorus chemical fertilizers and also to study the rate of Cd intake by people with age and gender differences. To investigate the Cd status in wheat-cultivated lands, 105 soil samples and also 24 wheat samples were collected from three land uses of rainfed, irrigated, and control one. Phosphorus levels were also measured in soil samples to investigate the relationship between the amount of chemical fertilizer consumption and the amount of Cd. The mean values of available Cd were 0.15, 0.18, and 0.08 (mg/kg) under three land-use types of rainfed, irrigated, and control one, respectively, and the mean values of total Cd were also 1.9, 2.22, and 1.30 in the rainfed land, irrigated land, and control one, respectively. The results showed that the amount of available and total Cd in the irrigated and rainfed lands was higher than the amount of Cd in the control sample. According to the results of Cd fractionation, the highest amounts of Cd were in the residual, carbonate, organic, soluble, and exchangeable fractions, respectively. The amounts of Cd in the three parts of root, stem, and grain were 1.08, 0.65, 0.91 (mg/kg), respectively. Finally, the results showed that the rate of Cd entry into the children’s body was higher than that of adults and the elderly.