Impact of functional microbes on nitrogen removal in artificial tidal wetlands in the Yangtze River estuary: Evidence from molecular and stable isotopic analyses

• Published in: Journal of cleaner production 2021-03, Vol.287, p.125077, Article 125077
• Main Authors: Zhang, Manping, Huang, Jung-Chen, Sun, Shanshan, Ur Rehman, Muhammad Muneeb, He, Shengbing, Zhou, Weili
• Format: Article
• Language: English
• Subjects: Greenhouse gas emission; Microbial pathways; Nitrogen removal; Stable isotope; Tidal wetlands
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2020.125077

After decades of rapid development in the delta, the worsening water quality in the Yangtze River estuary has become a concern in China. To improve the situation, we explored the use of two tidal wetland mesocosms (PA and NP), by evaluating nitrogen removal performance, greenhouse gas emissions and underlying molecular mechanisms. Our results show the mesocosms removed ∼23.9% of TN from nitrate-dominated river water (1.20 mg L−1), with PA twice effective as NP, which is consistent with the molecular and stable isotopic data. The emissions of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) were low in the soil of both PA and NP, while integrated microbial analyses suggest nitrification was the major contributor of nitrite to anaerobic ammonium oxidation (anammox) and also the dominant ammonia removal pathway in the mesocosms, particularly PA. The simultaneous dissimilatory nitrate reduction to ammonium (DNRA), anammox, denitrification and nitrification had mainly contributed to the nitrogen removal and greenhouse gas emission reduction, with rates of 0.86–2.05, 11.94–24.38, 44.95–340.95, and 458.56–1046.91 nmol N2 g−1 dry soil d−1, respectively. This study would expand our understanding of the nitrogen-cycling in tidal wetlands, helping develop a sustainable solution to the water pollution problem in the Yangtze River estuary. [Display omitted] •Tidal wetland PA (planted) was twice effective in removing TN as NP (unplanted).•Low CH4, CO2 and N2O emissions were produced in both PA and NP.•Nitrification played a key role in NH4+ removal and nitrite supply for anammox.•Microbial pathways associated with N transformation were active in both PA and NP.•The tidal system provided an effective way of treating micro-polluted river water.