Enhanced microbial nitrification-denitrification processes in a subtropical metropolitan river network.
Yingxue Xuan1, Yingwen Mai2, Yunqiu Xu2
1School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China.
Water Research
|July 22, 2022
Summary
Urban rivers show distinct microbial communities that accelerate nitrogen cycling. High pollution drives changes in bacteria, enhancing nitrification and denitrification processes in these ecosystems.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Ecotoxicology
Background:
- Urban rivers are significant sources of nitrogen pollution and transformation.
- Microbial communities in urban rivers differ from natural ones, but their role in nitrogen cycling is unclear.
Purpose of the Study:
- To investigate nitrogen transformations and microbial communities in a metropolitan river network.
- To understand how urbanization impacts microbial nitrogen cycling.
Main Methods:
- Utilized nitrogen (N) nutrients-related isotope technology (natural-abundance isotopes and isotope-labeling).
- Employed bioinformatics methods including 16S rRNA high-throughput sequencing and quantitative PCR.
- Analyzed bacterial community structure, functional gene abundances, and N transformation rates.
Main Results:
- Highly urbanized rivers exhibited higher bacterial richness, lower complexity, and increased abundances of nitrification and denitrifying bacteria compared to suburban rivers.
- Abundances of nitrifier (amoA) and denitrifier (nirK, nirS) genes were significantly higher in urbanized rivers.
- Nitrification and denitrification processes were accelerated in highly urbanized rivers, evidenced by isotope data and transformation rates.
Conclusions:
- Excess nitrogen pollution in urban rivers shapes specific aquatic bacterial communities.
- These altered microbial communities enhance nitrification-denitrification processes in urban river networks.
- The study expands the application of isotopic and bioinformatics methods for studying microbial nitrogen cycling in urban ecosystems.
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