A comparative study of methods for determining carbonate content in marine and terrestrial sediments

Abstract

Abstract Carbonate can be produced in a variety of environments on the Earth's surface, such as shallow seas and deep oceans, continental lakes, soils and subsurface aquifers. The carbonate content of sediments is an important proxy in paleoceanography and paleoclimatology and is often used to reconstruct paleoenvironmental evolution of the earth. Many methods have been reported to measure the content of carbonate in sediments, but how those methods perform (e.g. degree of accuracy and precision, error-induced factors, operability, cost and time) remains understudied. Here, we employ three widely-used non-instrumental methods, including acid-base titration, gasometric method, and loss on ignition (LOI) based on muffle combustion, together with X-ray diffraction for mineral phase analysis, to compare the carbonate content data of sediments from deep ocean (water depths from 1218 m to 6147 m) of the western Pacific and Cenozoic sedimentary rocks from the Qaidam basin, northern Tibetan Plateau. The results show that data accuracies of most methods are closely related to mineral compositions in sediments (e.g. carbonate species and clay mineral contents) and analytical operations. Non-instrumental methods generally demonstrate low precisions (avg. RSD of 3.36%) in determining sediments with low carbonate contents (