Hazardous microplastic characteristics and its role as a vector of heavy metal in groundwater and surface water of coastal south India

Study of hazardous microplastics in the natural water resources is minimal compared to the sea salt, seafood and even packaged water. We presented results of the first baseline research of microplastics in groundwater and surface water from the coastal south India (Tamil Nadu state) and evaluated the heavy metal adsorption capacities of different polymers. The microplastics (up to 19.9 particles/L) were of relatively larger size in surface water (0.34-4.30 mm) compared to the groundwater (0.12-2.50 mm). Polyamide (nylon), polyester, polypropylene, polyethylene, polyvinyl chloride and cellulose were the common polymers and all of them showed different capacities of heavy metal adsorption. In two different experimental sites, the polypropylene showed higher capacity of adsorption compared to other polymers in the following orders: (i) cadmium > manganese > lead > arsenic and (ii) manganese > zinc > arsenic > lead > copper. The polyamide, however, exhibited better adsorption only for manganese. Similar to other recent findings, our results associate microplastics as a major vector to transport heavy metals in the water system. Formulation of strategies to reduce the environmental risks of particulate plastics as a potent vector for transportation of the toxic trace elements and subsequent, impact on human health through the OSPRC framework (Origins, Sources, Pathways, Receptors and Consequence) in the study area would require future research.

Automated summary

The study revealed the presence of larger microplastics in groundwater and surface water in coastal south India, with different polymers showing varying capacities for heavy metal adsorption. Polypropylene demonstrated the highest adsorption capacity for heavy metals among all tested polymers.