The applicant has made his great efforts in studying the geochemistry in the surficial geo-systems and in understanding of global climatic and environmental changes, and gained some outstanding achievements both in geochemical methodology and paleoclimate reconstructions. The methodology achievements: 1) Establish and improve the high-efficient methods for analyzing high-precision Sr/Ca and Mg/Ca ratios in corals based on ICP-MS, ICP-AES and LA-ICP-MS. This has significantly pushed the development of the coral paleoclimate reconstruction studies in China. 2) Establish and improve the low blank method for analyzing high-precision boron isotope in various materials, which enables a leading study in reconstructing the history of ocean acidification. The achievements of theoretical and application studies are as follows: 1) Discover the out of phase phenomenon in the seasonal variations of precipitation and temperature in the northern South China Sea during the mid-Holocene. 2) Reconstruct the records of seawater pH changes in the past ~200 years on coral reefs from the Great Barrier Reefs, and discover the climatic effects on the natural variability of seawater pH, and outline the links between the anthropogenic CO2 emissions and the trend of ocean acidification. This is essential to understand the mechanism of global ocean acidification. 3) Discover the mechanism for the mobilization and re-distribution of the elements during intensive chemical weathering, and the significant fractionation of Nd and Hf isotopic systematics during intensive chemical weathering, which has not been reported before. 4) Establish the method for tracing chemical weathering in the source regions of the marine sediments, and further decipher their paleoclimatic information. This extends the application of geochemical methods in paleoceanography studies. The applicant will make further studies on the variations of seawater pH, and seek for the insight mechanism for seawater pH change. These studies are helpful in understanding the processes and the mechanism of ocean acidification.