Dissimilatory nitrate reduction and functional genes in two subtropical rivers, China

• Published in: Environmental science and pollution research international 2021-12, Vol.28 (48), p.68155-68173
• Main Authors: Zhao, Binjie, Li, Xinshuai, Wang, Yang, Tan, Xiang, Qi, Wenhua, Li, Hongran, Wei, Junwei, You, Yong, Shi, Wenjun, Zhang, Quanfa
• Format: Article
• Language: English
• Subjects: Ammonium; Ammonium Compounds; Anaerobic Ammonia Oxidation; Anaerobic processes; Aquatic ecosystems; Aquatic environment; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Autumn; Carbon; Denitrification; Dissolved organic carbon; Dissolved Organic Matter; Earth and Environmental Science; Ecosystem; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Humans; Nitrate reduction; Nitrates; Nitrates - analysis; Nitrogen - analysis; Oxidation; Oxidation-Reduction; Reduction; Research Article; River ecology; Rivers; Seasonal variations; Sediments; Spring; Spring (season); Summer; Total organic carbon; Waste Water Technology; Water Management; Water Pollution Control; Water temperature
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-15197-3

Dissimilatory nitrate reduction processes, including denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA), are important pathways of nitrate transformation in the aquatic environments. In this study, we investigated potential rates of denitrification, anammox, and DNRA in the sediments of two subtropical rivers, Jinshui River and Qi River, with different intensities of human activities in their respective catchment, China. Our objectives were to assess the seasonality of dissimilatory nitrate reduction rates, quantify their respective contributions to nitrate reduction, and reveal the relationship between dissimilatory nitrate reduction rates, functional gene abundances, and physicochemicals in the river ecosystems. Our results showed higher rates of denitrification and anammox in the intensively disturbed areas in autumn and spring, and higher potential DNRA in the slightly disturbed areas in summer. Generally, denitrification, anammox, and DNRA were higher in summer, autumn, and spring, respectively. Relative contributions of nitrate reduction from denitrification, anammox, and DNRA were quite different in different seasons. Dissimilatory nitrate reduction rates and gene abundances correlated significantly with water temperature, dissolved organic carbon (DOC), sediment total organic carbon (SOC), NO 3 - , NH 4 + , DOC/NO 3 - , iron ions, and sulfide. Understanding dissimilatory nitrate reduction is essential for restoring nitrate reduction capacity and improving and sustaining ecohealth of the river ecosystems.