天津地表水中有机碳来源的同位素示踪研究

Using Stable Carbon Isotopes to Identify the Sources of Organic Carbon in Surface Waters of the Tianjin District

地表水中的有机碳是陆地水生生态系统的核心组分之一,可以反映流域生态环境概况,也是全球生物地球化学循环研究的重要组成部分。本研究通过系统采集天津地区地表水体的水样和水体颗粒物样品,完成了稳定碳同位素及相关组分测定,对天津地表水中的颗粒有机碳和溶解有机碳的来源进行了探讨。研究结果显示,天津地表水体中颗粒有机碳的δ13 C值主要分布于-22‰～-36‰之间,主要来源于城市污水释放和水体自身的浮游植物。溶解有机碳的δ13 C值主要分布于-25‰左右,主要来源于污水贡献。对于天津地表水体中颗粒有机碳和溶解有机碳来说,流域土壤侵蚀释放的有机碳贡献比例都很小。

Organic carbon, one of the important constituents and an effective environmental indicator in the terrestrial aquatic ecosystem, is an important link in the global carbon cycle. In the present study, the δ^13C values of Particulate Organic Carbon （POC） and Dissolved Organic Carbon （DOC） in surface waters of the Tianjin District were measured to investigate their potential sources. The results showed that the δ^13C values of POC range from -22‰ to -36‰, fully indicating that POC is derived from city sewage water and planktons. The δ^13C values of DOC have an average value of -25‰, implying the overwhelming contribution of city sewage. Inspire of POC or DOC, organic carbon that is derived from soil erosion has only very limited contributions.