湖泊环境早成岩作用对沉积物中有机质C_N和碳同位素组成的影响.docVIP

 湖泊环境早成岩作用对沉积物中有机质 C/N 和碳同位素组成的影响# 张成君，张菀漪，樊荣，郜逗* 5 10 15 20 25 30 35 40 （兰州大学资源环境学院，兰州 730000） 摘要：本文通过对青藏高原可可西里 28 个湖泊，以及中国东北地区 26 个湖泊表层沉积物中 13 13 明，湖泊沉积物中有机质在迁移、聚集过程中不仅遭受细菌的分解，而且早期成岩作用对有 13 母质的判断。在有机质的演化过程中，沉水植物、藻类和 C4 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-16‰~-20‰范围；陆生植物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‰范围；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‰范围。沉积物早期成 岩作用的强度、湖泊中细菌作用，以及湖泊水体滞留时间等对有机质有较大的改造作用。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。 关键词：湖泊；有机质；早成岩作用；C/N；有机质碳同位素组成 中图分类号：Q911 Early diagenesis impacting C/N and organic isotopic compositions in the lacustrince sediments Zhang Chengjun, Zhang Wanyi, Fan Rong, Gao Dou (School of Resources and Environmental Sciences, Lanzhou University, LanZhou 730000) Abstract: C/N, organic isotopic compositions and organic n-alkane components have been analysized to the lake 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 the same time, early diagenesis can impact the ratios of C/N and the values of δ13Corg at the beginning of terrestrial and aquatic plants inputting the lake waterbodies. Degrading of bacteria and early diagenesis can be lower the C/N and δ13Corg obviously in the process of transferring and accumulation of organic matter. Changed C/N and δ13Corg 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 maybe in the range of -16‰ to -20‰; Organic matter from 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 general, the intensity of early diagenesis, action of bacteria and the residuum time of lake waterbodies can remake primary organic matter. Isotope of the terrestrial plants changed less can indicate primary environ