Did the COVID-19 pandemic play a role in the spatial and temporal variations of microplastics? Evidence from a tropical river in southern India.

Personal protective equipment (PPE) use has increased because of COVID-19, producing more microplastics (MPs). The pandemic's impact on MP pollution in Indian rivers is little understood. In this study, the Netravathi River in Karnataka was investigated for the spatiotemporal distribution of MPs. The MPs abundance, size, and categories varied seasonally, with a higher concentration during the monsoon seasons. The reduction in rainfall during MON20 and the COVID-19 lockdown can be the reasons for the significant decrease in the MP concentration when compared to MON19. Polyethylene and polyethylene terephthalate were the most abundant polymers, with a shift from polyethylene to the latter (74 %) during post-monsoon season post-lockdown. The situation of MP pollution in Western Ghats can be mitigated with the aid of appropriate waste management of plastic trash and greater public awareness about the disposal of single-use plastics, which has risen significantly during the COVID-19 pandemic.

Assessment of pollution and risks associated with microplastics in the riverine sediments of the Western Ghats: a heritage site in southern India.

There is very little knowledge on microplastic pollution in the Western Ghats (WG), a heritage site in southwest India. To address this, we have studied the spatiotemporal variations of sedimentary microplastics (MPs) from the River Sharavathi, a pristine river in the Western Ghats (WG), southern India. The rich biodiversity in the region makes it relevant to analyse the distribution of this emerging pollutant that is causing harm to the biota and the ecosystem. We analysed the sedimentological and carbon content (organic and inorganic) of these sediments and explored their relationship with MPs. Finally, risk assessment indices such as the Pollution Load Index (PLI), the Polymer Hazard Index (PHI), and the Potential Ecological Risk Index (PERI) were calculated to detect the levels of plastic pollution. The concentration of MPs ranged from 2.5 to 57.5 pieces/kg and 0 to 15 pieces/kg during the pre-monsoon and post-monsoon seasons, respectively. The dip in the MPs' abundance during the post-monsoon season was due to the extremely high rainfall in the river basin during July-August 2019, which would have entrained the sedimentary MPs and transported them to the coast/Arabian Sea. Smaller MPs (0.3-1 mm) were more abundant than the larger MPs (1-5 mm), mainly due to the breakdown of sedimentary plastics by physical processes. Fragments, films, foams, and fibres were the main categories of MPs, and the main polymers were polyethylene, polyethylene terephthalate, and polypropylene. No significant relationship was observed between the sedimentological properties and microplastics, which may be due to the different physical properties of sediments and microplastics. The PLI, PHI, and PERI indices suggest different contamination levels in the river basin. Based on the PLI scores, all the samples belong to the hazardous level I suggesting minor risk category, and the risk of microplastic pollution falls under the high to hazardous risk category based on the PHI values. The PERI value ranged from 160 to 440 and 40 to 2240 during the pre-monsoon and post-monsoon seasons, respectively. The risk assessment in a region known for its rich biodiversity is crucial, as the data can be used by the district administration to mitigate plastic pollution.