Dissimilatory nitrate reduction in urban lake ecosystems: A comparison study between closed and open lakes in Chengdu, China

Zhanbiao Yang; Lan Lu; Zhang Cheng; Junren Xian; Yuanxiang Yang; Lixia Liu; Xiaoxun Xu

doi:10.1016/j.watres.2022.118218

Dissimilatory nitrate reduction in urban lake ecosystems: A comparison study between closed and open lakes in Chengdu, China

Water Res. 2022 May 1:214:118218. doi: 10.1016/j.watres.2022.118218. Epub 2022 Feb 23.

Authors

Zhanbiao Yang¹, Lan Lu², Zhang Cheng², Junren Xian², Yuanxiang Yang², Lixia Liu³, Xiaoxun Xu⁴

Affiliations

¹ College of Environment Sciences, Sichuan Agricultural University, Chengdu 611130, China. Electronic address: z.b.yang@sicau.edu.cn.
² College of Environment Sciences, Sichuan Agricultural University, Chengdu 611130, China.
³ College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
⁴ College of Environment Sciences, Sichuan Agricultural University, Chengdu 611130, China. Electronic address: xuxiaoxun@sicau.edu.cn.

PMID: 35231805
DOI: 10.1016/j.watres.2022.118218

Abstract

Urban lake ecosystems play important roles in nitrogen cycling, yet the occurrence, contribution and mechanism of nitrate reduction in urban closed and open lakes (UCL and UOL) remain unclear. On November - December of 2020, the potential rates of denitrification (DEN), anammox (ANA), and dissimilatory nitrate reduction to ammonium (DNRA) were quantified using slurries incubations in six urban lakes of Chengdu, China. The environmental variables, genes abundance (nirS, hzsB and nrfA), bacterial 16S rRNA gene were also measured. UOL had higher water ammonium (NH₄⁺), nitrate (NO₃^-) and nitrite (NO₂^-), and sediment NH₄⁺, NO₃^-, total organic carbon (TOC) and ferrous iron (Fe²⁺) content than UCL. The potential rates of DEN and anammox in UOL were 2.16- and 3.45-times more than in UCL, respectively. Conversely, the DNRA rate in UCL was 1.20-fold higher than UOL. Higher nirS and hzsB abundance were found in UOL, while higher nrfA abundance occurred in UCL. High-throughput sequencing analysis showed that the relative abundance of DEN bacteria was higher in UOL (2.59-12.30%) than in UCL (1.96-6.70%) at the genus level, while the relative abundance of DNRA bacteria was higher in UCL (2.02-4.19%) than in UOL (1.14-2.31%). The difference in the relative abundance of anammox bacteria at the genus level was not significant. Multiple linear regression showed that the physicochemical properties and nitrate reduction bacteria together control the potential nitrate reduction rates. Since a higher nitrogen retention capability appears in UCL, according to the nitrogen retention index (NRI), further management should be focused on urban closed lakes to avoid the potential for eutrophication.

Keywords: Bacterial community; Dissimilatory nitrate reduction; Potential rate; Sediment; Urban lakes.