咸化水体中DIC的同位素组成及环境过程分析

Isotopic composition and environmental behavior of dissolved inorganic carbon in brackish surface water

系统采集了天津地区地表水样品，对其溶解无机碳的稳定碳同位素比值（δ^13CDIC）及相关化学组成进行了全面测定，以期对咸化并且受到污染水体中的溶解无机碳的来源和迁移转化特征进行探讨。研究结果显示，天津地表水中溶解无机碳的δ^13CDIC值主要分布于0.27‰～14.9‰之间，显示了相对较宽的分布范围。同时，天津地表水体具有非常高的溶解无机碳浓度，浓度范围分布于155～1000mg／L之间，主要分布区间为200～500mg／L。从溶解无机碳浓度及其同位素组成特征分析，水体咸化引起的水／气界面的大气CO2气体交换和水体自身有机质降解过程是天津地表水溶解无机碳的两个最主要来源。

In the present study, δ^13 of the Dissolved Inorganic Carbon （DIC） in brackish surface waters of Tianjin were measured to investigate its potential sources and cycling mechanism. The results show that δ^13 values of DIC in the Tianjin surface waters range from 0.27‰ to 14.9‰, displaying a wide range comparing to most of other surface water of the world. The concentrations of DIC also show very high values that range from 155 mg/L to 1000 mg/L, mainly from 200 mg/l to 500 mg/L. Those δ^13 values and concentrations of DIC indicated that atmospheric CO2 and organic carbon decomposition were two major sources of DIC for the Tianjin surface waters.