Investigations on the co-occurrence of microplastics and other pollutants in River Yamuna, Delhi

Yamuna River is a threatened resource of freshwater in Delhi, India. The present study is focused on investigating three important contaminants, namely microplastics (MPs), heavy metals, and fecal coliforms in the surface water of this river with major emphasis on MPs occurrence and characterization. MPs showed an increase in abundance in the river from Wazirabad barrage (n = 500 MPs/m(3)) to Okhla barrage (n = 3,900 MPs/m(3)) in Delhi, with a maximum abundance downstream to Najafgarh and Shahdara drain outfalls. White color and fragmented shape were prevalent characteristics of the isolated MPs. ATR-FTIR spectroscopy revealed five types of polymers. Heavy metals (Cr, Pb, Mn, Fe) and fecal coliforms were at unacceptable levels at most of the sampling sites. Due to the emergence of issues concerning MP's tendency to actively interact with heavy metals and pathogenic microorganisms, investigation of the co-occurrence of such harmful pollutants is very important. The present study is aimed at this issue and urges similar kinds of investigations in other riverine regions of our country as well as globally due to their scarcity in literature. This study can further provide a baseline database to help the Government of India's efforts to clean and revive the Delhi stretch of the Yamuna River. HIGHLIGHTS Microplastics (MPs) were prevalent across the Yamuna River stretch with a mean abundance of 1.78 x 10(3) MPs/m(3). MPs were most abundant near the wastewater discharge points of Najafgarh and Shahdara drains. In addition to MPs, the presence of co-contaminants like heavy metals and fecal coliforms in the study area was also a serious concern. Co-contaminant interactions may disturb the balance of several biological systems.

Automated summary

The Yamuna River in Delhi, India, is facing threats from pollution, particularly microplastics, heavy metals, and fecal coliforms. The abundance of microplastics increases as the river flows from Wazirabad barrage to Okhla barrage, with the highest levels found downstream to Najafgarh and Shahdara drain outfalls. The presence of co-contaminants like heavy metals and fecal coliforms is also a serious concern. The study emphasizes the importance of investigating the co-occurrence of these harmful pollutants and calls for similar research in other riverine regions.