Impact of iron and manganese nano-metal-oxides on contaminant interaction and fortification potential in agricultural systems - a review

Rising population growth and increase global food demand have made meeting the demands of food production and security a major challenge worldwide. Nanotechnology is starting to become a viable remediation strategy of interest in farming. Ultimately, it may be used as a sustainability tool in agricultural systems. In these roles, it could be used to increase the efficiency of techniques such as food monitoring, pathogen control, water treatment and targeted delivery of agrochemicals. In addition to these uses, nanoparticles, particularly nano-metal-oxides (NMOs), have been engineered to act as contaminant scavengers and could be applied to a wide range of systems. Numerous studies have investigated the scavenging ability of NMOs, but few have investigated them in this role in the context of agricultural and food systems. Within these systems, however, research has demonstrated the potential of NMOs to increase crop health and yield but few have studied using NMOs as sources of key micronutrients, such as Fe and Mn. In this review, we address previous research that has used Fe-and Mn-NMOs in agricultural systems, particularly the worldwide crop production of the four major staple foods - rice, wheat, maize and soybeans - highlighting their application as fertilisers and sorbents. Fe- and Mn-NMOs are strong candidates for immobilisation of agricultural contaminants in soils and, because they are naturally ubiquitous, they have the potential to be a cost-effective and sustainable technology compared with other remediation strategies.