Source: Wuhan Botanical Garden

Wetlands enjoy the reputation of the "Kidney of the Earth" and have attracted global attention in terms of intercepting pollutants and improving water quality. Wetlands can reduce nitrogen pollution through various means such as plant absorption, soil fixation, and soil microbial processes (including denitrification and anaerobic ammonia oxidation). Among them, the denitrification pathway reduces nitrate nitrogen to nitrogen and enters the air, thereby permanently removing nitrogen. Current research has some understanding of the denitrification of wetlands, but little is known about the rate of denitrification of wetlands under the influence of environmental and biological factors under different hydrological conditions.

Recently, Deng Danli, a PhD student in the Wetland Ecology Group of the Wuhan Botanical Garden, Chinese Academy of Sciences, and Pan Yongtai, a PhD student at Tibet University, under the guidance of researchers Liu Guihua, Liu Wenzhi, and assistant researcher Ma Lin, Taking the Danjiang River, a non-point source polluted river in the water source area of the middle line of the South-to-North Water Transfer Project, as the research object, the potential denitrification and background denitrification rates of sediments in 36 rivers, streams, ponds and ditches in its watershed were measured and quantified by qPCR Analyze the abundance of denitrifying microorganisms. The study found that the ditches have the highest denitrification rate and abundance of denitrifying microorganisms. The denitrification rate has a strong seasonality, and the denitrification rate is higher in June. In rivers and streams, nitrogen and carbon concentrations are significantly positively correlated with the rate of denitrification, but this correlation is not found in ponds and ditches. The denitrification rate is significantly negatively correlated with water flow rate and viscosity. The results show that hydrological conditions, especially flow velocity and hydrological pulses, can play an important role in the biogeochemical process of nitrogen in wetlands.

The research results were published in Science of the Total Environment under the title of "Seeking the hotspots of nitrogen removal: A comparison of sediment denitrification rate and denitrifier abundance among wetland types with different hydrological conditions". The research was supported by National Natural Science Foundation of China, CRSRI open research project and youth innovation promotion association of Chinese Academy of Sciences.

Framework of research ideas

Paper link: https://doi.org/10.1016/j.scitotenv.2020.140253

Source: http://www.cas.cn/syky/202007/t20200706_4752145.shtml

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