High-resolution Geochemical Studies Of The Holocene Loess-paleosol Profile In The Upper-reaches Of The Huaihe River

Nowadays human are facing up with a series of global environmental problems which never occurred before. Global changes especially in climate have deep impacts on both economic development of all the countries and survival of human beings. Studies of the Holocene environmental evolution is an essential part of "PAST GLOBAL CHANGES" (PAGES) and has a vitally important reference value to forcasting future environmental changes. Many methods were introduced into the studies and great progress was made. The loess-paleosol sequence in the Loess Plateau which is located in Northwest China was accepted as a wonderful information carrier. The formative mechanism, source of loess-paleosol and history of climatic changes in the Loess Plateau was made clear through the studies of the loess-paleosol sequence.Through field exploration, sampling and experimenting, we gained a lot of datum of chemical elements, magnetic susceptibility, pH value, content of calcium carbonate and loess-on-ignition which have an important indicative significance to paleoclimatic evolution. We studied mainly the distributing law of different kinds of chemical elements in the loess-paleosol profile and probed into their geochemical characteristics, indictive significance to pedogenic environmental changes and the Holocene climatic change laws with the combination of other environmental indexes, and the source of aeolian loess-paleosol was studied simultaneously.The results are very important for understanding regional response to global changes in the semi-humid zone within the upper reaches of the Huaihe River Basin.The results are as follows:1. The contents of major element oxides (Al₂O₃, Fe₂O₃, K₂O and MgO ), heavy metal elements(Zn,V,Co,Cu and Ni) and other microelements(Rb,Ga) varied similarly in the Holocene aeolian loess-paleosol profile, that is, the contents of these elements reached highest in the paleosol(So) and then in the modern topsoil(MS), and lowest in the loess(Li, Lt, Lo). The contents of other heavy metal elements (Nb,Pb,Ti and Cr) in the modern topsoil(MS) were higher than that in the paleosol slightly which showed that modern pedogenic reconstruction was very strong during the late Holocene. Na₂O and Sr eluviated in the paleosol and congregated relatively in the loess. The contents...