Geochemical fixation of carbon dioxide in the environment

Abstract

Characteristics of carbonate deposition in the environment are ubiquitous distribution, extensive production by organic activities and long-term stabilization of reactive organic carbon. Since enormous amount of carbon dioxide has been fixed in carbonate deposits during the evolution of life, the study of fixation-fluxes in carbonates and their mechanisms acquires considerable importance of clarifing the present globalclimate changes. From the view point of carbon dioxide sinks in the enironment, we propose three major objectives of carbonate study: the estimates of cardon dioxide fluxes fixed by carbonates, the detection of the global climate changes recorded in the past carbonates with fine time resolution, and the modeling of global carbon cycles. The following is a list of important subjects for each objectives. (1) Flux measurements: photosynthesis of calcium carbonate in coral reef, calcification by calcareous algae, carbonate desolution in deep-sea sediments, rate and mechanisms of carbonate preicipitation. (2) Detection of past climate changes: paleoclimate changes with fine time resolution, time determination with fine time resolution, microanalysis of trace elements and isotopes, quantitative measurements of diagenetic processes, and reading sedimental records of climate related to short time scales. (3) Simulation: chemical reaction of carbonates in aqueous systems and global circulation of carbon fluxes.