Eutrophication in lakes caused by excess nitrogen (N) inputs has stimulated research on the ability and mechanism of lakes to remove excess N input from watersheds. As one of the main processes contributes to N retention, sediment denitrification could permanently remove N through the conversion of nitrate (NO₃^-) to dinitrogen (N₂) gases and the potent greenhouse gas - nitrous oxide (N₂O).  

There are two factors regulating denitirifation and N₂O production: Proximal controls (available carbon, NO₃^- concentration and oxygen supply in overlying water and sediment) and distal controls (land use, plant communities and soil texture). However, till now, the study of sediment denitrification and affecting factors is limited.  

A research team led by Prof. LIU Guihua from Wuhan Botanical Garden measured the potential denitrification, unamended denitrification, and N₂O production rate of 68 sediment samples from 20 lakes located in the Yunnan-Guizhou Plateau of China with varying watershed land uses by using the acetylene block technique and the gas chromatograph.  

Based on the model proposed by Seitzinger et al. (2006), researchers estimated that large quantities of annual N inputs (36.43-81.4%) in the 20 plateau lakes can be removed via sediment denitrification. The sediment denitrification was significantly related to water chemistry or sediment properties and human land uses. In huaman-dominated lakes, the denitrification and N₂O production rates were controlled primarily by sediment properties, especially the N contents, while in reference lakes, they were generally controlled by water chemistry.  

This study entitled “Sediment denitrification and nitrous oxide production in Chinese plateau lakes with varying watershed land uses” was published in Biogeochemistry. Funding was provided by the Special S&T Project on Treatment and Control of Water Pollution and the National Science Foundation of China.