Implications of observed inconsistencies in carbonate chemistry measurements for ocean acidification studies

[摘要] The growing field of ocean acidification research is concerned with theinvestigation of organism responses to increasing pCO₂ values. Oneimportant approach in this context is culture work using seawater withadjusted CO₂ levels. As aqueous pCO₂ is difficult to measuredirectly in small-scale experiments, it is generally calculated from twoother measured parameters of the carbonate system (often A_T,C_T or pH). Unfortunately, the overall uncertainties of measured andsubsequently calculated values are often unknown. Especially under highpCO₂, this can become a severe problem with respect to theinterpretation of physiological and ecological data. In the few datasets fromocean acidification research where all three of these parameters weremeasured, pCO₂ values calculated from A_T and C_T aretypically about 30% lower (i.e. ~300 μatm at a targetpCO₂ of 1000 μatm) than those calculated from A_T andpH or C_T and pH. This study presents and discusses these discrepanciesas well as likely consequences for the ocean acidification community. Untilthis problem is solved, one has to consider that calculated parameters of thecarbonate system (e.g. pCO₂, calcite saturation state) may not becomparable between studies, and that this may have important implications forthe interpretation of CO₂ perturbation experiments.

[学科分类] 地球化学与岩石