Microplastics in freshwater lakes: A case study from Southern India

Microplastics (MP) are prevalent and virtually present in all environmental domains. Though microplastics are reported worldwide, only limited studies have been carried out in freshwater ecosystems. Therefore, this study was initiated to evaluate the presence of microplastics in a freshwater lake (Vellayani Lake), located in Thiruvananthapuram, Kerala, Southern India. The water quality of this lake assumes significance as it serves as a primary drinking water source for thousands of people in Thiruvananthapuram. This study analyzed the seasonal distribution of microplastics in water samples from three locations within Vellayani Lake under two distinct climatic conditions, identifying microplastics in all sampled locations. During the monsoon sampling, the abundance of MP ranged from 20 to 100 particles/m3, with an average abundance of 65 particles/m3 and a total abundance of 194 particles/m3. However, during the summer, microplastic concentrations ranged from 34 to 67 particles/m³, with an average abundance of 49 particles/m³ and a total abundance of 147 particles/m³. Four varieties of polymers, High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Polypropylene (PP), and Polyethylene Terephthalate (PET), have been detected. HDPE is the most abundant polymer in the water, along with PP, PET, and LDPE. The dominance of Polyethylene and Polypropylene polymers in the lake water samples highlights the rapid disintegration of single-use disposable plastics. The consumption of microplastics has been proven to be harmful, and their long residence time and widespread presence in the water make it necessary to develop new purification techniques to specifically target plastic contaminants.