Nanomaterials for soil contaminant remediation

Soil is the foundation of agriculture, but it is also a major sink for anthropogenic pollutants. Excessive emissions of domestic and industrial waste and chemicals from agricultural application can impose a tremendous burden on the soil ecosystem because of their limited degradation rates under natural conditions. In particular, persistent organic pollutants such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons, halogenated hydrocarbons, phthalates, and organophosphorus pesticides are classes of compounds commonly found in agricultural soils, with sources derived from pesticides, electrical insulators, surfactants, solvents, and flame retardants, and other industrial chemicals/processes. In addition, mining, smelting, exhaust gas discharge, and sewage irrigation can lead to the release of toxic metals/metalloid elements [e.g., chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), manganese (Mn), arsenic (As), and mercury (Hg)] into soil.4 Moreover, emerging substances that are widely used as pharmaceuticals and personal care products have garnered increasing concern. Many pollutants are likely to adsorb to soil particles because of their high molecular stability and low solubility; these contaminants may subsequently enter the food chain after absorption by crops and threaten human health. Importantly, contamination of farmland globally limits the available arable land for agricultural production and exacerbates food insecurity, causing a massive waste of grain each year. Considering that the global demand for food is predicted to increase by 50%–70% by 2050, developing cost-effective and sustainable remediation technologies for soil contamination is thus imperative.7