以分子标志化合物研究珠江口陆源有机碳百年演变特征与环境变化反演

河口在全球碳的生物地球化学循环中发挥着重要作用。近百年来珠江流域由于人口的快速增长和人类活动的急剧变化，陆源物质输入的增加对珠江口及邻近海域的自然生态过程包括碳循环都产生了重要影响。本项目通过对沉积记录的研究来了解珠江口陆源有机碳百年演变特征，反演区域环境变化，研究结果将有利于对珠江口及邻近海域未来环境演变趋势作出科学预测。项目将通过对珠江口系列柱状沉积物进行高碳数正构烷烃、木质素和甘油二烷基甘油四醚 (GDGTs) 的定性定量研究，结合对珠江流域 (东江、西江、北江) 河流表层沉积物、两岸典型土壤及植被的上述分子标志化合物的定量研究，定量计算珠江口各类陆源有机碳的相对输入贡献，重建珠江流域的大气平均温度, 通过高碳数正构烷烃的δD值重建气候干/湿。在此基础之上探讨珠江口近百年来陆源有机碳的演变特征及与气候/环境变化和人类活动的可能关系，为典型河口地区碳循环研究提供机制上的参考

Estuaries are sites of significant land–sea interaction and play a disproportionately important role in the carbon biogeochemical cycles globally. Substantially increased terrestrial matter input into the Pearl River Estuary due to the rapid population growth and increasing human activities, which makes a significant disturbance to the estuarine ecosystems including the carbon bio-geochemical cycle during the past centenary. However, the information on the land vegetation types and environmental change history over the past 100 years is scarce due to the absence of the actual observation records, which restricts the scientific prediction on the environmental changes in the Pearl River estuarine system.. This research is focused on the compositions of molecular biomarkers related to the terrestrial organic carbon and the paleoenvironmental reconstruction in the Pearl River Estuary over the past 100 years. Several aspects will be involved, including: (1) the quantitative and qualitative research of land plant biomarkers in the short sediment cores from the estuary will performed, which could provide the information on the types of the land plants in the past. (2) The composition and distribution of glycerol dialkyl glycerol tetraethers (GDGTs) in the short sediment cores will be investigated, which could provide the information on the sources of GDGTs. GDGT-based indices will be calculated and the relative contribution of the soil would be evaluated. (3) The composition and distribution of lignin phenols in the short sediment cores will be studied and the types of the vegetation will be reconstructed for the same core sediment. (4) All these molecular biomarkers will be studied for the typical soils, land plants and surface sediments collected from the Pearl River systems. (5) The stable isotopes (δD and δ13C) of long-chain n-alkanes will be investigated, which could provide the information on the relative humidity of the climate and the C3/C4 palnts. All these achievements would enable us to elaborate the variations of terrestrial organic carbon and evaluate the relationship between the inputs of the terrestrial organic carbon and the paleoenvironmental change in the Pearl River Estuary since last 100 years.