Background: Cadmium contamination is becoming an important issue globally due to its high toxicity and carcinogenicity, leading to detrimental effects on both environmental and human health. This review paper discusses the different sources of cadmium, its toxic effects on the environment and human health, and the influence of different soil factors in changing the speciation and bioavailability of cadmium in soil. This paper also covers research on different remediation strategies currently available for reducing cadmium bioavailability. Methods: Previous research and critical comparison of cadmium extent, toxicity, effects and management were studied Results: The carcinogenic nature of Cadmium is of significant human health concern. Cadmium is found in both free and complexed forms, where its availability depends on its speciation in soil. In soil, oxidizing conditions and high pH decrease cadmium bioavailability and speciation. Here, organic matter can also act as both a sink and source of cadmium and microbes perform many mobilization processes including protonation, chelation, and chemical transformation whereas, sorption or precipitation decreases cadmium availability. Continuous exposure to cadmium can result in browning, decomposing and mucilaginous roots, shoot reduction and apical growth of root, chlorosis, and rolling of leaves. Toxicity may inhibit lateral root formation or can result in rigid, twisted, and browning of the main root. Toxicity also affects photosynthesis and the availability of mineral nutrients. In this paper, the remediation techniques of soil polluted by Cd, including biological, chemical and physical remediation are reviewed. The methods of remediation, developing trends, drawbacks, and strengths were also reviewed to provide a reference for the research in this field to date. Conclusion: Although cadmium toxicity is of great concern, many remediation techniques can be successfully used to mitigate its adverse effects. Phytoremediation, hyperaccumulation, bioremediation, and the application of different amendments to the soil have all been successful in alleviating cadmium bioavailability. Amongst all available techniques, in-situ immobilization with inorganic, organic or clay amendments is an environmentally friendly and cost-effective strategy to remediate cadmium contaminated soils and achieve sustainable agriculture production.

The present study aimed to evaluate the effect of soil-applied Zn and Cu on absorption and accumulation of Cd applied through irrigation water in legume (chickpea and mung bean) and cereal (wheat and maize) crops. The results revealed that Cd in irrigation water at higher levels (2 and 5 mg L⁻¹) significantly (p < 0.05) reduced the plant biomass while the soil application of Zn and Cu, singly or combined, favored the biomass production. Plant tissue Cd concentration increased linearly with the increasing application of Cd via irrigation water. While Cd application caused a redistribution of metals in grains, straw, and roots with the highest concentration of Cd, Zn, and Cu occurred in roots followed by straw and grains. Zinc addition to soil alleviated Cd toxicity by decreasing Cd concentration in plant tissues due to a possible antagonistic effect. The addition of Cu to the soil had no consistent effects on Zn and Cd contents across all crops. Inhibitory effects of Cd on the uptake and accumulation of Zn and Cu have also been observed at higher Cd load. Thus, soil-applied Zn and Cu antagonized Cd helping the plant to cope with its toxicity and suppressed the toxic effects of Cd in plant tissues, thus favoring plant growth.

With the growing scarcity of water, the remediation of water polluted with heavy metals is the need of hour. The present research work is aimed to address this problem by adsorbing heavy metals ions (Pb (II) and Cr (VI)) on modified graphene oxide having an excess of carboxylic acid groups. For this, graphene oxide (GO) was modified with chloroacetic acid to produce carboxylated graphene oxide (GO-COOH). The successful synthesis of graphene oxide and its modification has been confirmed using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray Diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission electron microscopy (TEM). The increase in surface area of graphene oxide after treatment with chloroacetic acid characterized by BET indicated its successful modification. A batch experiment was conducted to optimize the different factors affecting adsorption of both heavy metals on GO-COOH. After functionalization, we achieved maximum adsorption capacities of 588.23 mg g⁻¹ and 370.37 mg g⁻¹ for Pb and Cr, respectively, by GO-COOH which were high compared to the previously reported adsorbents of this kind. The Langmuir model (R² = 0.998) and Pseudo-second-order kinetic model (R² = 0.999) confirmed the monolayer adsorption of Pb and Cr on GO-COOH and the chemisorption as the dominant process governing adsorption mechanism. The present work shows that the carboxylation of GO can enhance its adsorption capacity efficiently and may be applicable for the treatment of wastewater.