Yan Gao a, 1, Zhenhua Zhang a, Xinhong Liu a, Neng Yi a, Li Zhang a, Yan Wang a, Shaohua Yana
aInstitute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing 210014, China;
Abstract
Biogenic gas production in a eutrophic pond located in the subtropical climate zone of China was quantified using a newly developed gas-trapping device. This device allows for a vertically resolved collection and subsequent analysis of biogenic gases (N2, O2, N2O and CH4). Determining the vertical structure of gas production is especially relevant in stratified water bodies as it allows to link the stratification of physicochemical parameters with the gases produced. The investigated pond exhibited strong thermal stratification in temperature, DO, pH, nutrients and Chlo-α during summer and autumn, but not in winter. Gas production was greatest at the sediment-water interface and in the surface layer and small in the middle layer. Gases produced at the surface were mainly N2 and O2, whereas the latter is likely to stem from photosynthetic activity as gas production followed a diurnal cycle. At the sediment-water interface, the collected gas was mainly composed of N2 and CH4. Our results highlight the vertical heterogeneity of gas production and underline the value of vertically-resolved sampling which is made possible with the presented gas-trapping device.