珠江水体悬浮物颗粒有机碳稳定同位素组成及分布特征

Characteristic of the Organic Carbon-isotope Composition and Contribution of Suspended Matter in the Pearl River

研究了珠江三干流西江、北江和东江水体中悬浮物颗粒有机碳稳定碳同位素的组成、分布以及季节变化特征。研究结果显示:可以根据.C_3、C_4植物及悬浮物的δ^(13)C值区分不同流域的植被覆盖状况;东江流域水土流失区以草地、农田为主,C_4植物影响较大;北江水体中颗粒有机碳主要来源于森林覆盖区,同位素组成受C_3植物影响较大;西江水体中颗粒有机碳同位素组成介于其间,同时受C_3、C_4植物影响,颗粒有机碳部分来源于森林覆盖土壤,部分来源于草地和农田。

The paper studies the characteristic of the contribution and seasonal change of organic carbon isotope composition(δ^(13)C) in the Pearl River. According to the δ^(13)C value of C_3, C_4 plant and river suspended matter, we can discern the state of plant covered in different water and soil loss area. The water and soil loss area in the Dongjiang River basin was mainly grassland and cropland. The water and soil loss area in Beijiang River basin was lots of subtropical forests. The results indicated that we can discern the condition of plant covered in different basins. POC of Beijiang mainly originated from forest area and its carbon-isotope composition was affected by C_3 plant. The carbon-isotope composition of Xijiang is between that of Beijiang and Dongjiang's. It indicated that the suspended matter was affected by C_3 and C_4 plant at the same time. And part of POC in Xijiang River originated from the soil covered by forest, some came from grassland and cultivated land.