摘要
本文通过对青藏高原可可西里28个湖泊和中国东北地区26个湖泊表层沉积物中有机质C/N比值、有机碳同位素组成(δ^(13)C_(org)),以及有机质饱和烃组分特征的分析,探讨了这些参数对湖泊沉积物中有机质来源的指示和早期成岩作用对C/N、δ^(13)C_(org)的影响。研究表明,湖泊沉积物中有机质在迁移、聚集过程中早期成岩作用对有机质的作用比较明显,改变了沉积物中有机质C/N和δ^(13)C_(org),以至于影响这些参数对原始母质来源的判断。在有机质的演化过程中,沉水植物、藻类和C_4植物的降解作用最为强烈,初始有机质碳同位素组成可能在-17‰^-20‰;陆生植物C_3的降解作用相对较小,有机碳同位素组成的变化也相对较小,初始值可能在-26‰^-30‰;水生浮游、挺水植物的降解作用中等,有机碳同位素组成的变化中等,初始值可能在-20‰^-26‰。沉积物中早期成岩作用与有机质类型、湖泊水体性质、深度、滞留时间等有关,造成有机质C/N比值和碳同位素组成的降低,陆生植物来源的有机质碳同位素组成可能能更好地代表原始环境信息。
C/N, organic carbon isotopic compositions and organic n-alkane components have been analyzed in surface sediments from 28 lakes in the Koh Xil area and 26 lakes in the northeastern China. It is shown that organic sources can be indicated by these biogeological proxies. And at the same time, early digenesis can impact the ratios of C/N and the values of δ^13Corg at the beginning of terrestrial and aquatic plants inputting the lake water bodies. Early digenesis can lower the C/N and δ^13Corg obviously in the process of transferring and accumulation of organic matter. Changed C/N and δ^13Corg cannot indicate organic sources very accurately. Submerged plants, algae and C4 grasses degrade most intensively in the evolvement process of organic matter. Original values of organic isotope may be in the range of - 17‰ to -20‰; Organic matter mainly from C3 terrestrial plants changes in minimum and original organic isotope is about -26‰- -30‰; floating aquatic and emergent macrophytes are in the mid, and original isotope is about - 20‰ - - 26‰. In generaX, organic matter in the lakes is remade with types of organic matter, water characteristics, depth and residue time of lake waterbodies. Isotope of the terrestrial pXants changed less can indicate primary environments preferably.
出处
《地球环境学报》
2012年第4期1005-1012,共8页
Journal of Earth Environment
基金
国家自然科学基金面上项目(41173015)
教育部博士点基金(20100211110020)
