Synchronous Nutrient Controlled-Release of Greenhouse Gases During Mineralization of Sediments from Different Lakes.

Lake sediments, as an important emission source of nutrients and greenhouse gases, play a crucial role during the biogeochemical cycle processes. However, the impact mechanisms of different nutrient levels on greenhouse gas emission from lakes are still insufficient. In this study, the sediments from eight shallow lakes in the middle and lower reaches of the Yangtze River were cultured to study the release characteristics of greenhouse gases more than one month. Results showed that the greenhouse gases during the mineralization processes of sediments were mainly released to the atmosphere instead of being dissolved in the overlying water. The released concentrations of CH and CO were as high as 1 × 10 μmol L in the later stage of the experiment, while the concentration of NO was relatively low with a maximal value of about 10 μmol L. In addition, all the lake sediments displayed a nutrient release to the overlying water, where the concentrations of TC, TOC, TN, NH-N and TP were up to 173.0, 102.7, 36.7, 30.8 and 6.34 mg L, respectively. The nutrient levels of different lake sediments are symmetrical to the released nutrients concentrations in the overlying water. The further statistical analysis illustrated a synchronous nutrient controlled-release of greenhouse gases, that is, the higher the levels of nutrients in the sediments, the higher the concentrations of greenhouse gases released. These findings provide a better understanding that the control of endogenous nutrient levels of sediments is extremely important for lacustrine management, which can play a positive role in mitigating the greenhouse gas emissions from lake sediments.