https://jhmr.hsu.ac.ir/ Journal of Heavy Metal Research en daily 1 Sun, 01 Feb 2026 00:00:00 +0330 Sun, 01 Feb 2026 00:00:00 +0330 https://jhmr.hsu.ac.ir/article_234136.html Heavy metal contamination poses a significant threat to plant health, soil quality, and agricultural productivity. This review explores the sources, physiological impacts, and biochemical mechanisms underlying heavy metals toxicity in plants. Common heavy metals of concern include cadmium (Cd), lead (Pb), mercury (Hg), nickel (Ni), chromium (Cr), copper (Cu), and zinc (Zn), which originate from both natural processes and anthropogenic activities and anthropogenic activities including industrial emissions, fertilizers, pesticides, and wastewater irrigation. Excessive accumulation of these elements disrupts plant metabolism by generating reactive oxygen species (ROS), leading to oxidative stress, enzyme inhibition, membrane damage, and impaired photosynthesis. Experimental studies show that cadmium and nickel stress significantly alter antioxidant enzyme activities—such as catalase, peroxidase, and superoxide dismutase—indicating a defensive response to oxidative imbalance. Morphological symptoms of metal toxicity include chlorosis, stunted growth, reduced yield, and reproductive failure. In addition to direct plant effects, heavy metals disturb soil microbial communities, alter pH, and inhibit processes like nitrogen fixation and decomposition. Effective mitigation requires regular soil monitoring, use of biochar and organic amendments, phytoremediation with hyperaccumulator plants, and balanced nutrient management. Understanding these interactions provides a foundation for sustainable soil management and the development of resilient crop systems in metal-polluted environments. This review synthesizes current understanding of heavy metal ecotoxicology in agricultural systems and emphasizes the need for integrated management approaches to ensure food safety and environmental sustainability. https://jhmr.hsu.ac.ir/article_233671.html The escalating issue of heavy metal contamination in industrial effluents, particularly from Iran's burgeoning petrochemical and metallurgical sectors, necessitates the development of cost-effective and sustainable remediation technologies. This study investigates the potential of natural and modified minerals sourced from significant Iranian deposits for the adsorptive removal of heavy metals from synthetic industrial wastewater. Clinoptilolite-rich zeolite from Semnan Province and vermiculite from Gilan Province were subjected to a novel blended modification, combining acid (H₂SO₄) and surfactant (CTAB) treatments to create a multi-functional adsorbent. The performance of these materials was evaluated for the removal of Cr(III), Cr(VI), Cu(II), Ni(II), Cd(II), Pb(II), and Zn(II) ions from an initial concentration of 10 mg/L for each metal. Batch adsorption experiments were conducted by varying key parameters, including adsorbent concentration (10 g/L), pH (4, 6, 8), and the ratio of natural to modified minerals. Characterization using XRD, FTIR, and BET analysis confirmed structural and surface chemical changes post-modification, leading to enhanced surface area and active site availability. Results demonstrated that modified vermiculite was exceptionally effective, achieving removal efficiencies exceeding 98% for Pb(II) and Cr(VI) under optimal conditions (pH 6, 60:40 a cost-effective 60:40 natural-to-modified mineral ratio). Modified zeolite also showed significant removal capabilities, particularly for Cu(II) and Zn(II). Kinetic studies indicated rapid initial adsorption, with equilibrium reached within 60-90 minutes for most metals. Multiple regression analysis yielded robust predictive models (R² > 0.97) for the tested parameter space, linking final pollutant concentrations to variables such as removal percentage and mineral adsorption capacity. This research highlights the immense potential of locally sourced, geochemically characterized Iranian minerals as a sustainable solution for industrial wastewater treatment, offering a practical pathway to mitigate environmental pollution and support circular-economy principles in the region, while acknowledging the need for further validation under more complex, competitive conditions. https://jhmr.hsu.ac.ir/article_233144.html  This study investigates the potential of using treated municipal wastewater to irrigate fenugreek, spinach, radish, and carrot crops in Neyshabur, Iran, as a sustainable response to water scarcity in arid regions. Greenhouse experiments were conducted under three irrigation regimes—100% groundwater (control), 50% wastewater blend, and 100% wastewater—to assess growth performance, yield, and soil and plant quality. Irrigation with 100% wastewater significantly enhanced plant growth, biomass, leaf area, and yield, particularly in fenugreek, due to the wastewater’s high nutrient content (nitrogen, phosphorus, potassium, and organic matter), which improved soil fertility despite increased salinity and pollution indicators (EC, BOD, COD). Heavy metal analyses revealed elevated concentrations of Pb, Ni, Zn, Cu, Cr, and Cd in soils irrigated with wastewater, yet all remained below international safety standards. Although metal accumulation in plant tissues rose with wastewater use, concentrations were within FAO/WHO permissible limits, except for cadmium (Cd), which showed a transfer factor (TF) greater than 1 in root vegetables, indicating higher mobility from soil to edible parts. Overall, treated wastewater proved to be a promising alternative water and nutrient source for vegetable cultivation in water-limited areas like Neyshabur, enhancing productivity without immediate health risks, though continuous monitoring of cadmium accumulation is essential to prevent potential long-term soil and food safety issues. https://jhmr.hsu.ac.ir/article_233145.html This study evaluates the economic feasibility of recycling critical and hazardous heavy metals from two major waste streams in Iran—spent batteries containing lead and cadmium, and electronic waste rich in copper and gold. Using an integrated analytical framework that combines Cost-Benefit Analysis (CBA) and Life Cycle Cost (LCC) modeling, it assesses recycling as a strategic pathway toward sustainable development under conditions of environmental stress, limited resources, and economic sanctions. The analysis draws on data from 2015 to 2025, including international metal prices, national waste generation, and energy and water costs, alongside technical process estimates. Results demonstrate strong economic potential for both recycling pathways: one metric ton of spent lead-acid batteries generates a net economic benefit of $350–$450, largely due to lead recovery and reduced environmental damage, while one ton of mixed electronic waste (PCBs) yields over $2,500, driven by the recovery of copper and gold. Energy savings contribute an additional 15–25% to total benefits, even with low domestic energy prices. Sensitivity analysis identifies international metal price fluctuations and collection efficiency as key determinants of profitability. Overall, the study concludes that heavy metal recycling is not only environmentally essential but also economically viable for Iran, offering a means to enhance resource efficiency, reduce pollution, and foster circular economy development. To realize this potential, policy actions are needed to formalize informal recycling sectors, adjust energy pricing mechanisms, and introduce targeted incentives that attract investment. These measures could enable Iran to transform its waste management system into a resilient, value-generating circular economy model aligned with the Sustainable Development Goals. https://jhmr.hsu.ac.ir/article_233968.html This study provides the first systematic baseline assessment of Platinum Group Metals (PGMs: Pt, Pd, Rh) and associated toxic heavy metals (Pb, Cd, Zn, Ni, Cr) in spent automotive catalytic converters (SACCs) from Iran's most prevalent vehicles. The unique composition of the Iranian fleet, dominated by a mix of older licensed European models and modern domestic and imported cars, creates a distinct SACC waste stream whose characteristics are largely undocumented. Samples from eight common models were systematically collected, prepared, and analyzed using Inductively Coupled Plasma–Mass Spectrometry (ICP–MS) and X-ray Fluorescence (XRF). The results reveal significant inter-model variability, directly linked to vehicle age and technology. A clear technological transition was observed, from older, Pt-dominant catalysts (e.g., Peugeot 405, with total PGMs up to 4,850 mg/kg) to newer, Pd-dominant, and lower-loading designs (e.g., Mazda 3, ~1,255 mg/kg). Critically, SACCs from older, high-volume models were found to be a particularly rich secondary PGM resource. Concurrently, significant concentrations of hazardous metals were quantified, with lead (Pb) reaching up to 750 mg/kg in older models—a legacy of past leaded gasoline use—and zinc (Zn) exceeding 2,000 mg/kg across all samples. These findings underscore the dual nature of SACCs in the Iranian context: a high-value "urban ore" for critical metals and a hazardous waste stream requiring stringent environmental management. This foundational dataset provides the crucial evidence base needed to develop a tailored national SACC recycling strategy, one that can harness the economic opportunity of PGM recovery while mitigating the environmental risks posed by toxic metal contaminants, thereby advancing circular economy principles in the region. https://jhmr.hsu.ac.ir/article_236949.html Nowadays, the adverse effects of toxic metals on humans are well-known. Large-scale production and the demand for new electronic devices have made electronic components a significant source of toxic elements. This work focused on examining the exposure to residential toxic metals and metalloids in electronic components repairers by analyzing their scalp hair and nail samples. In this study, 19 electronic component repairers were selected based on the required criteria for the study, including different ages and employment durations. Hair and nail samples as biological tissues were collected from them and analyzed to detect the toxic elements. The results showed that smoking and filled teeth were effective in increasing the value of toxic elements in these people. High levels of Zn and Sn were obtained in the nails compared to hair samples, including 310.5 and 204.7 μg/g for nails and 254 and 77.1 μg/g for hair, respectively, and the concentration levels of the studied elements were found in the rank order of Zn>Sn>Pb>Ni>As>Se>Cr>Cd. Our study confirmed that there was a strong correlation between nail selenium content and nail As burden (r=0.907, p=0.028). We realized that Sn and Pb had a strong correlation together due to the use of solder joints in the repairing process by the repairers. This study shows that human scalp hair and nails could be useful biomarkers to assess the extent of toxic metal exposure in the repairer of electronic components. https://jhmr.hsu.ac.ir/article_242564.html The Niger Delta region of Nigeria faces persistent water quality challenges driven by rapid urbanization, oil-related industrial activity, and aging infrastructure. Despite numerous environmental assessments in the region, drinking water quality within schools—where children represent a highly vulnerable population—remains largely unexplored. This study provides a targeted evaluation of metal(loid) contamination in tap water from 30 primary and secondary schools distributed across urban (Port Harcourt, Warri) and peri-urban/rural communities. Concentrations of Pb, Cd, As, Hg, Cr, Ni, Cu, Zn, Fe, and Mn were determined using atomic absorption spectrometry, with rigorous QA/QC procedures. Samples were collected under flushed conditions and acidified, representing total recoverable metal fractions. Mean concentrations (µg/L) decreased in the order Zn > Fe > Cu > Mn > Pb > Ni > Cr > As > Cd > Hg. Lead exceeded the WHO guideline (10 µg/L) in 47% of schools. Entropy-Weighted Water Quality Index (EWQI) results classified 80% of samples as excellent to good, whereas 20% were medium to poor. Multivariate analyses (PCA with KMO = 0.72; Bartlett’s p < 0.001) identified two dominant factors: (1) infrastructure-related corrosion (Pb–Zn–Cu–Fe) and (2) geogenic/industrial influences (As–Hg–Cr). Health risk assessment following USEPA guidelines indicated that non-carcinogenic risk was generally below the safety threshold (HI < 1), although exceedances occurred in 10% of schools for children. Carcinogenic risk values for Pb and As surpassed the acceptable limit (1 × 10⁻⁴) in 30% of locations. Although limited by sample size and single-season sampling, the findings highlight infrastructure deterioration as a key determinant of school drinking water quality and underscore the need for systematic monitoring and targeted remediation to protect children’s health. https://jhmr.hsu.ac.ir/article_243060.html India’s rapidly expanding economy relies heavily on the mining sector to supply raw materials for energy production, infrastructure development, and industrial growth. However, mining activities generate vast quantities of waste, including overburden, waste rock, and tailings, which pose serious environmental and social challenges. These wastes may release toxic elements and contribute to land degradation, water contamination, and long-term ecological risks. This review examines how circular economy principles can be applied to mining waste management in India, with the aim of transforming waste streams into valuable resources while minimizing environmental impacts. The study evaluates several strategic approaches, including waste minimization at the source, reprocessing of historical tailings to recover residual metals, and upcycling of mineral waste into construction materials such as bricks, blocks, ceramics, and geopolymer binders. The paper also discusses the environmental implications of heavy metal contamination associated with mining waste, highlighting the risks posed by elements such as arsenic, lead, and cadmium in mining regions. In addition, emerging technologies such as digital monitoring systems, advanced mineral processing techniques, and artificial intelligence–based resource management are reviewed as tools that may support more sustainable mining practices. The results indicate that integrating circular economy strategies into India’s mining sector could significantly reduce waste volumes, recover valuable metals, and support more sustainable resource utilization. These approaches provide both environmental and economic benefits and represent an important pathway toward responsible mineral resource management. https://jhmr.hsu.ac.ir/article_243368.html Metal ions are integral to biological chemistry, underpinning structural organization, catalytic reactivity, and regulatory control in living systems. Current estimates indicate that roughly one-third of all proteins require a bound metal cofactor to achieve functional competence. This review examines the roles of selected first-row transition metals, nickel (Ni), chromium (Cr), zinc (Zn), copper (Cu), manganese (Mn), and cobalt (Co), in protein structure and function, emphasizing the mechanistic principles that govern their biological activity. We analyze how metal coordination shapes protein folding landscapes, stabilizes native conformations, and enables small structural domains such as zinc fingers to attain functional architecture. In contrast, we discuss how aberrant metal binding to unfolded or non-native states can disrupt folding pathways, promote aggregation, and contribute to proteotoxic stress. The catalytic versatility of these metals is explored in the context of metalloenzymes, where redox cycling and Lewis acid chemistry facilitate reactions ranging from energy metabolism to antioxidant defense. Additionally, we highlight the role of metal-responsive transcription factors that couple intracellular metal availability to gene expression, thereby maintaining homeostatic balance. Finally, we examine the pathological consequences of metal dyshomeostasis, including carcinogenesis, neurodegeneration, and cardiovascular toxicity. Together, these perspectives underscore the delicate equilibrium between essential metal utilization and metal-induced toxicity that defines metal–protein interactions in health and disease.