Main Factors Impacting the CO2 Flux Between Sediment and the Atmosphere in an Intertidal Zone, Qingdao

Using a Li-8100 automated soil CO₂ flux system (Licor, Lincoln, Nebraska, USA), we measured the in situ diurnal CO₂ flux from the sediment to the atmosphere in a temperate intertidal zone in northern China in 19 days during April 24 to July 26 of 2006, with average CO₂ flux of 0.09 mumol m^-2 s^-1. The CO₂ flux varied with redox potential and temperature. When the redox potential was <300 mv, the correlation coefficient between the daytime average CO₂flux and the daytime average redox potential was 0.963 (p = 0.001; n = 7) and the redox potential mainly regulated CO₂ flux. When the redox potential ranged from 300 mv to 500 mv, both redox potential and temperature affected CO₂ flux significantly and the correlation coefficients reached 0.912 (p = 0.088; n = 4) and 0.996 (p = 0.004; n = 4), respectively. When the redox potential was greater than 500 mv, redox potential is no longer a factor limiting CO₂ flux, thus leaving temperature the only influential factor, with a correlation coefficient of 0.889 (p = 0.018; n = 8) between CO₂ flux and temperature.