The Yamuna River, one of the most polluted rivers in the world, has been found to contain various contaminants. Agricultural fields near the river in Delhi-NCR region are irrigated with the river water itself, thus posing a great threat to human health as well as adverse effects on the soil microbial community. The present study evaluated the impact of this irrigation process on enzyme activity and microbial community of soil. Three sets of five pots each were treated with river water sampled from six different sites (two upstream, two middle stream, and two lower stream) within the stretch of Yamuna river in Delhi-NCR region, while the soil sample treated with tap water was taken as control. The result indicated that the soil sample treated with river water from lower stream had much higher level of organic pollution as shown by higher value of TOC (total organic carbon) as well as dehydrogenase and nitrate reductase enzyme activities. ARISA-ADAPT analysis showed overall, Firmicutes (50.84%) were the most abundant bacterial group followed by Proteobacteria (33.32%) and Actinobacteria (12.46%). They displayed a higher percentage of variability in relation to the contamination of river water. Furthermore, specific bacterial groups such as Acidobacteria, Verrucomicrobia, and Aquificae were exclusively found in soil samples that had been treated with river water. The study concludes that increase in the organic pollutants in the river water significantly alter the composition of microbial population as well as the soil enzyme activity. These microbial communities could be used in identifying the level of pollution in river water so that improved management techniques can be adopted.
Sharma et al. (Tue,) studied this question.