Diurnal and seasonal variations of CO2 flux across water-air interface in artificial wetland in the boreal zone of China

Using the static chamber method, CO
2
flux across the water-air interface of Nihe reservoir was measured for 24 hours over a one-year cycle in China. Gas ebullition and gas emission in winter was not considered in this study. According to our results, Nihe reservoir was a total carbon source (690.42 ± 15.18 mg m
⁻²
d
⁻¹
) during the year. The maximum and minimum CO
2
flux were 50.52 (mg m
⁻²
h
⁻¹
) and 17.87 (mg m
⁻²
h
⁻¹
), respectively. The diurnal and seasonal variation of CO
2
flux was obvious: the CO
2
emission during the daytime was lower than night; the CO
2
flux was highest in summer (31.52±2.27 mg m
⁻²
h
⁻¹
), and lowest in fall (25.03 ± 3.21 mg m
⁻²
h
⁻¹
). CO
2
emission was negatively correlated with temperature, wind speed, and chlorophyll, while positively correlated with alkalinity. Ultimately, no single environmental factor can solely responsible for CO
2
flux.