The Method Estimating Daytime CO2 Flux Between Intertidal Sediment and the Atmosphere


  •  Pengjin Yang    
  •  Longjun Zhang    

Abstract

The daytime variation in CO2 flux between the intertidal sediment and the atmosphere was great and impacted by environmental elements. This paper analyzed the daytime variation in CO2 flux between the intertidal sediment and the atmosphere and concluded its different rules during the ebb tide and flood tide. During the ebb tide, the CO2 flux rose as the tide ebbed and its rate of change was different when the redox potential changed (0.13umol m-2 s-1 per 100 cm height of the tide at Eh<=300mv, 0.15umol m-2 s-1 per 100 cm height of the tide at 300mv<Eh<500mv and  0.07umol m-2 s-1 per 100 cm height of the tide at Eh>=500mv). During the flood tide, the CO2 flux maintained the largest of the day and almost unchanged with the increase of water level. The average CO2 flux in the flood tide increased with the increase of the redox potential at Eh<=300mv and 300mv<Eh<500mv, but their linear regressions between the average CO2 flux and the redox potential were different. Compared with the average CO2 flux at Eh<=300mv and 300mv<Eh<500mv, the average CO2 flux was no longer related to the redox potential but related to temperature at Eh>=500mv. According to these rules, the daytime CO2 flux can be calculated  based on limited measurements well and truly. The fitting straight line equation between the estimated and measured CO2 flux was y= 0.9353x+0.0872(R2 = 0.75, P <0.01).



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