Qualitative and Quantitative Analysis of Microplastics in the Surface Waters and Freshwater Fish from Four Important Lakes in Pune, India

Abstract

Freshwater ecosystems, especially lakes, constitute vital reservoirs of potable water, irrigation resources, and aquaculture habitats. However, there is a lack of comprehensive data regarding the prevalence of microplastics (MPs) in freshwater lakes of densely populated metropolitan regions in the Indian Subcontinent. In this study, we have investigated the qualitative and quantitative attributes of MPs in the surface waters of four important lakes in Pune, India: (i) Kasarsai, (ii) Pashan, (iii) Manas, and (iv) Mastani. Our analyses revealed prevalent contamination across all four lakes, with Kasarsai lake exhibiting the highest mean MPs abundance of 14.03 ± 5.41 particles/L. Primary morphotype of MPs detected in the water samples were fibres and the dominant size was between 100 µm to 1000 µm. Additionally, in terms of colour, transparent microplastics were prominent. Fourier Transform Infrared Spectroscopy (FTIR) revealed that polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) were the main types of MPs present in water samples. Furthermore, we assessed the abundance of MPs ingested by commercially available edible fish Tilapia, Oreochromis niloticus, collected from these lakes. We observed maximum ingestion of MPs in the fish from Kasarsai lake, which was 2.8 ± 2.9 particles per individual fish. To evaluate the possible health risks on humans, Estimated Daily intake (EDI) and Microplastics Cancer Risk (MPCR) index were determined for adults and children. EDI of PP was highest for Kasarsai and Manas lake, while, EDI of PE was predominant for Pashan and Mastani lake. For all four lakes, the MPCR index of PE was highest in both adults and children, with the maximum reaching to 0.52 for children consuming water from Pashan lake. Our findings raise concerns about the potential negative effects of MPs on freshwater ecosystem and the health of humans consuming the water and fish from such lakes. An ambitious strategy involving the collective efforts of the general public is required to address this hazard.