Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Harbin Institute of Technology, School of Civil and Environmental Engineering, Shenzhen, 518055, China.
Environ Pollut. 2020 Aug;263(Pt A):114478. doi: 10.1016/j.envpol.2020.114478. Epub 2020 Apr 5.
Currently, wastewater treatment plant (WWTP) upgrades have been implemented in various countries to improve the water quality of the receiving ecosystems and protect aquatic species from potential deleterious effects. The impact of WWTP upgrades on biological communities and functions in receiving waters is a fundamental issue that remains largely unaddressed, especially for microbial communities. Here, we selected two wastewater-dominant rivers in Beijing (China) as study sites, i.e., one river receiving water from an upgraded WWTP to explore the impacts of upgrade on aquatic ecosystems and another river receiving water from a previously upgraded WWTP as a reference. After a five-year investigation, we found that WWTP upgrade significantly decreased total organic nitrogen (N) in the receiving river. As a biological response, N-metabolism-related bacterioplankton are accordingly altered in composition and tend to intensively interact according to the network analysis. Metagenomic analysis based on the N-cycling genes and metagenomic-assembled genomes revealed that WWTP upgrade decreased the abundance of nitrifying bacteria but increased that of denitrifying and dissimilatory nitrate reduction to ammonium (DNRA) bacteria in the receiving river, according to their marker gene abundances. After calculation of the ratios between DNRA and denitrifying bacteria and quantification of genes/bacteria related to ammonium cycling, we deduced the changes in N-metabolism-related bacteria are likely an attempt to provide enough bioavailable N for plankton growth as conservation of ammonium was enhanced in receiving river after WWTP upgrade.
目前，许多国家已经实施了废水处理厂（WWTP）升级改造，以提高受纳生态系统的水质，保护水生物种免受潜在的有害影响。WWTP 升级对受纳水体中生物群落和功能的影响是一个基本问题，但尚未得到充分解决，尤其是对微生物群落而言。在这里，我们选择了北京的两条以废水为主的河流（中国）作为研究地点，一条河流接收来自升级 WWTP 的水，以探索升级对水生态系统的影响，另一条河流接收来自之前升级 WWTP 的水作为参考。经过五年的调查，我们发现 WWTP 升级显著降低了受纳河中的总有机氮（N）。作为一种生物反应，与 N 代谢相关的浮游细菌的组成相应发生变化，并根据网络分析倾向于密集相互作用。基于 N 循环基因和宏基因组组装基因组的宏基因组分析表明，WWTP 升级降低了受纳河中的硝化细菌丰度，但增加了反硝化和异化硝酸盐还原为铵（DNRA）细菌的丰度，这是根据其标记基因丰度得出的。在计算 DNRA 和反硝化细菌之间的比例以及定量与铵循环相关的基因/细菌后，我们推断 N 代谢相关细菌的变化可能是为了提供足够的生物可利用氮以促进浮游生物生长，因为 WWTP 升级后受纳河中的铵保存增强。
