Heavy metal contamination in water and soil presents a growing global issue that poses significant risks to environmental integrity and human well-being. Various heavy metals, including arsenic (As), lead (Pb), mercury (Hg), cadmium (Cd), and chromium (Cr), contaminate ecosystems. These metals enter the environment through both natural processes and human activities such as coal mining, leather production, metal processing, agriculture, and industrial waste disposal. With their high toxicity and tendency to accumulate in organisms, heavy metals induce oxidative stress in cells, resulting in organelle damage. This toxicity can lead to genetic mutations and histone alterations. Given the severe effects of heavy metals, urgent actions are required to eliminate them from polluted soil and water. While physicochemical techniques like membrane filtration, precipitation, oxidation, and reduction exist, they have limitations. Hence, there is a pressing need to devise environmentally friendly and cost-efficient approaches for heavy metal removal. This article examines heavy metal contamination in water and soil, its adverse impacts, and the cleanup of heavy metals using eco-friendly methods. [GRAPHICAL ABSTRACT]

Biochar has been recognised as an efficacious amendment for the remediation of compound heavy metal contamination in soil. However, the molecular mechanism of biochar-mediated tolerance to compound heavy metal toxicity in cotton is unknown. The objective of this research was to investigate the positive impact of biochar (10 g.kg(-1)) on reducing damage caused by compound heavy metals (Cd, Pb, and As) in cotton ( Gos- sypium hirsutum L.). The results revealed that biochar reduced Cd concentrations by 24.9 % (roots), and decreased Pb concentrations by 37.1 % (roots) and 59.53 % (stems). Biochar maintained ionic homoeostasis by regulating the expression of metal transporter proteins such as ABC, HIPP, NRAMP3, PCR, and ZIP, and genes related to the carbon skeleton and plasma membrane. Biochar also downregulated genes related to photosynthesis, thereby increasing photosynthesis. Biochar re-established redox homoeostasis in cotton by activating signal transduction, which regulated the activity of the enzymes POD, SOD, and CAT activity; and the expression of related genes. This research revealed the molecular mechanism by which biochar confers resistance to the harmful effects of compound heavy metal toxicity in cotton. The application of biochar as a soil amendment to neutralise the toxicity of compound heavy metals is recommended for cash crop production.

Background Utilizing rice straw biochar (RSB) presents a novel approach to overcome toxicity of arsenic (As) in agricultural settings. Similarly, silicon (Si) has emerged as an effective agent for overcoming metal stress within agricultural crops. The present study investigates into the syringic application of RSB and Si in ameliorating As-induced stressed in Oryza sativa L. (rice) seedlings. Methods In the present study, we have used different levels of RSB (0, 2.5, and 5% w/w) and Si (0, 1.5, and 3 mM) to O. sativa seedlings when exposed to different levels of As stress i.e., 0, 50 and 100 mu M to examine plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, and the response of various antioxidants (enzymatic and non-enzymatic) and their specific gene expression, proline metabolism, the AsA-GSH cycle, cellular fractionation in the plants. Results Our results showed that the increasing concentration of As in the soil significantly (P < 0.05) decreased total plant length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight by 26, 12, 18, 34, 39 and 20% respectively, compared to the plants which were grown in the 0 M of As in the soil. Additionally, As stress in the soil increased the concentration of reactive oxygen species (ROS) causes oxidative damaged to membranous bounded organelles, increases organic acids, As concentration, affects antioxidants, proline metabolism, AsA-GSH cycle and cellular fractionation. Although, Although, the application of Si and RSB showed a significant (P < 0.05) increase in plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of Si and RSB enhanced cellular fractionation and decreased the proline metabolism and AsA-GSH cycle in O. sativa seedlings. Conclusion These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Heavy metals are often found in soil and can contaminate drinking water, posing a serious threat to human health. Molecular pathways and curation therapies for mitigating heavy metal toxicity have been studied for a long time. Recent studies on oxidative stress and aging have shown that the molecular foundation of cellular damage caused by heavy metals, namely, apoptosis, endoplasmic reticulum stress, and mitochondrial stress, share the same pathways as those involved in cellular senescence and aging. In recent aging studies, many types of heavy metal exposures have been used in both cellular and animal aging models. Chelation therapy is a traditional treatment for heavy metal toxicity. However, recently, various antioxidants have been found to be effective in treating heavy metal-induced damage, shifting the research focus to investigating the interplay between antioxidants and heavy metals. In this review, we introduce the molecular basis of heavy metal-induced cellular damage and its relationship with aging, summarize its clinical implications, and discuss antioxidants and other agents with protective effects against heavy metal damage.