Eutrophication Risk Assessment by Estimation of Denitrification Rate in Yamuna River Sediments

Abstract

Nitrogen loading in river systems is increasing the potential threat for eutrophication and human health due to reactive nitrogen species such as nitrate. In this study, we estimated the potential sediment denitrification rate in Yamuna River. The denitrification rate varied from 0.20 to 2.14 µg N g−1 DM h−1 in Yamuna River system with an annual mean value of 1.01 µg N g−1 DM h−1. Using nitrate disappearance method, the denitrification rate in Yamuna River varied from 1.01 to 3.24 µg g−1 h−1 and mean observed 1.92 µg g−1 h−1. We found that the denitrification rate was positively correlated with nitrate concentration, indicating river spread over the surface water regime offers nitrate for sediment denitrification process. Both the methods showed a significant positive correlation(r = 0.68). However, the rate calculated using acetylene inhibition method was 50% effective, suggesting this approach can be utilised for studying denitrification rate and eutrophication load in Yamuna River sediments.