Assessment of Spatial Distribution and Source Influence of Microplastic Contamination in the Socio-Religious Stretch of the Krishna River, Satara.

This study successfully quantified the MP load along the urban reach of the Krishna River in Satara, setting an important benchmark for freshwater ecosystems in Maharashtra. The study reveals an evident spatial pattern of higher MP loads, mainly influenced by point-source anthropogenic contamination. The Sangam-Mahuli junction (Station S2) acts as the prime environmental hotspot, with high loads of 3.7 MPs/L in surface water and 22 MPs/100g in riverbank sediments. Such high levels far exceed the benchmark levels at the upstream (S1, Vaduth) and downstream (S3, Mahagaon) sites. The elevated junction level can be attributed to socio-ritual activities at the Shri Kashi Vishweshwar temple and the Kailash Smashan Bhumi (cremation site). The occurrence of synthetic fibers and transparent films as the dominant microplastics suggests secondary contamination, which occurs due to the mechanical degradation of ritual textiles and municipal plastic waste. A crucial technical breakthrough made through this study was Using the improved 75 µm sieve stack enabled us to collect a large number of secondary microplastics, which cannot be detected at all using conventional 300 µm regulation sieves. This methodology allowed for capturing an extra 62%, where 38% were surface water microplastics, which fall exclusively into the 75-150 µm size interval, revealing that standard techniques grossly underestimate the problem. Morphological Characterization indicated absence of industrial primary pellets. The main microplastic constituent in sediments comprised of synthetic fibers (48.8%) and can be traced to decomposition of clothes in wash and bathing ghats. Films and fragments were identified as weathered polyethylene bags, used in nirmalya offerings, and clothes from river cremations. In order to prevent this contamination, physical screens and facilities for collecting nirmalya should be installed in the ghats by local officials. This research underscores the immediate necessity for local awareness and management strategies to curb microplastic contamination in Satara.

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