Composition Features Of Biological Markers In Paddy Soil In Chuodun Archaeology Site And Research Of The Change In The Paleoclimate And Paleoenvironment

Ancient soil contains regional and global changes information in the natural environment of different time scales. Ancient soil with a large number of inhabitants' activity in the area can be used to explore the natural environment of human activities and intensity of the response process. However, there were very little well-preserved ancient soils on the ancestors' sustainable activity of area. Launching this kind of research on Chuodun agricultural sites provided an excellent opportunity.Since this site was first excavated in 1982, we currently found much extremely rich information in this site. It has experienced four continuous cultural periods: a) Majiabang cultural periods, b) Songze cultural periods, c) Liangzhu cultural periods, and d) the culture of Maqiao. These four periods run across the Neolithic age recorded in the Taihu Lake region. Although scientists like archaeologists have made some encouraging results in the field of Cultural Relics and Archaeology, they mainly interested in excavated ancient artifacts. However, the ancient soil, which contains environmental changes and human activities, did not be concerned by archaeologists. The current researches on the ancient soil were limited to its particle size, magnetic susceptibility, and the clay minerals, but the researches on the lipid compounds for the identification of human activities and environmental changes of information in ancient rice soil have not yet commenced. Therefore, the study on the ancient soil lipid compounds is a field which need to be strengthen, not only provided indirect evidence for the archaeological work, but also has a great significance for understanding human activities during the Holocene, particularly, the influence of human farming activities on changing of the environment.In the thesis, we choice one of soil profile within a depth of 2m in Chuodun agricultural sites for the full study, and we analysis characteristics of lipid compounds like n-alkanes and saturated fatty acids, organic carbon, total nitrogen. The results obtained are described as follows:1. The studies of soil organic carbon, total nitrogen and C/N have shown that the soil profile may contained two cycles of soil layers which were formed ancient soil and modern rice soil. The segment of 200-174cm was considered as the mother of ancient soil layer, and the lower boundary of the ancient soil was located near the 162 cm segment. Near the 92 cm was the ancient soil surface, and at 174-92 cm of the ancient soil layer has undergone two significant developmental periods, from 136 cm divided into 174-136cm and 136-92 cm. And the segment from 92 to 68 cm was the deposition layer, and near 68cm was a new round of the beginning of the pedogenic process, and it was more anastomosis with ¹⁴C dating results.2. According to the parameters of n-alkanes and saturated fatty acids - CPI, A_H/A_L, F_H/F_L, C₃₁/C₁₇, C₂₇/C₃₁, CPI_(H)ALK and ACL, et al., we can see that Chuodun agricultural soil layer is located in a warm, hot and humid environment. It is slightly higher than nowadays' temperature in Taihu Lake area, and also has slightly larger humidity, so it is more suitable for crop growth. As the crustal movement and the expansion of sea-level, the region was often scoured by sea water, causing a large number of algae, bacteria and other biological injected into the soil, and also tested a lot of herbs identification from soil layers. It evidenced the existence of ancient rice soil in further. Based on the sudden decreased of n-alkanes and saturated fatty acids in> C₂₀ levels in ancient soil layers, the inference confirmed that Chuodun ancient paddy soil may be infected with a certain degree of "fire". It is may be due to our ancestors using the primitive farming methods: fire-irrigation cultivation system of paddy which caused a difference on the distribution of n-alkane carbon on ancient and modern rice territories.