Quantification of laboratory-simulated water-atmosphere CO2 fluxes in estuaries

Abstract

 Laboratory simulation of the processes that affect chemical species as they pass through estuaries is a useful tool for the study of these littoral systems. In this work, laboratory generation of the salinity gradients of several estuaries was performed using the steady state approach. We show how longitudinal salinity gradients can be generated in the laboratory, in order to characterize water-atmosphere CO₂ flux variations along different salinity gradients. Many natural estuaries, exposed to anthropogenic influence, show oversaturation of CO₂ relative to the atmosphere, with water pCO₂ values between 500 and 9500 µatm. In all the experiments performed, pCO₂ values higher than the mean atmospheric pCO₂ were obtained. On the other hand, all the experimentally quantified water-atmosphere CO₂ fluxes decrease exponentially with the increase in salinity. This same behaviour has been reported for several European estuaries by different authors.