Glacial atmospheric CO2 decline in association with decrease of marine sedimentary phosphorus

Abstract

The environmental and biogeochemical information extracted from the sediments collected from the northern shelf of the South China Sea shows that terrigenous inputs of phosphorus into the sea remained relatively constant, and the variation of phosphorus contents at different depths was caused by climatic and environmental changes. The findings also suggest that the vertical variation of phosphorus content was opposite to those of calcium carbonate and cadmium, and the functional correlation between CO 2 and PO 4 3− in seawater was given by calculating the chemical equilibrium, indicating that the accumulation of marine sedimentary phosphorus may have something to do with the variation of atmospheric CO 2 . The decreased phosphorus accumulation as well as the correspondingly-increased calcium carbonate content might be one of key factors causing glacial atmospheric CO 2 decline.Keywords: sedimentary phosphorus, calcium carbonate, atmospheric CO 2 , northern shelf of the South China Sea, biogeochemistry.Since the discovery from the ice-core record of South Pole revealed that atmospheric concentration of CO 2 of the last glacial was 80-100 ppm less than that of Holocene [1] , many researchers [2][3][4][5][6] have obtained a series of important findings to seek the dominant factors controlling its change from marine physical, chemical and biological processes, among which the view has gained increasing attention that phosphorus, as a macronutrient, is a crucial limitation to marine primary production, and ultimately affects atmospheric CO 2 and global climatic change [7,8] . Nevertheless, as how the biogeochemical cycle of phosphorus affected the concentration of atmospheric CO 2 is extrapolated mainly by studying modern processes at present, yet little was revealed about the response of phosphorus to paleoclimatology in geological records, there are no specific conclusions about how the biogeochemical process of phosphorus might lead to glacial atmospheric CO 2 change for lack of sound geological evidence as yet.In this paper, through analyzing the vertical variation of phosphorus content in the sediment column, and its correlation with the contents of calcium carbonate and cadmium, as well as theoretical calculation of the chemical equilibrium between different forms of phosphorus and CO 2 in seawater, discussed is the coupled relationship between the accumulation of sedimentary phosphorus and the change of atmospheric Glacial atmospheric CO 2 decline in association with decrease of marine sedimentary phosphorus 323 CO 2 from a biogeochemical point of view. The results provide novel evidence for revealing the predominant factors to pose the atmospheric CO 2 fall during the last glacial period.