西江流域水文水化学因子对岩溶系统碳汇通量的影响分析

Effects of the Hydrology-Water Chemistry Factors of the Xijiang River Basin on the Carbon Sink Flux in the Karst System

河流岩溶碳汇通量的研究对于掌握全球碳循环机制、寻找"遗漏碳汇"具有重要意义。水文地质特征是岩溶动力系统的重要单元,为了分析河流岩溶碳汇在通量、长时间尺度的变化,本文选取受湿润季风气候影响显著的西江梧州断面为研究对象,探讨了2011~2015年西江流域流量、水位、本地降水量、水温、pH值、电导率、Ca^(2+)和HCO_3^-浓度等水文水化学因子对岩溶碳汇通量的影响。结果表明:1岩溶碳汇通量与流量、水位的相关系数均在0.95以上,岩溶碳汇通量与流量达到了同步变化,岩溶碳汇通量与水位良好的相关关系则是通过水位对流量响应表现出来;降水通过不同方式进入河流直接改变地表径流状况,进而影响岩溶碳汇通量。2水温对岩溶碳汇通量的影响与西江流域雨季与夏季在同一时间段的气候特点有关,属于次要因子。3监测点水体常年呈弱碱性,pH值对岩溶碳汇通量的影响较弱;电导率、Ca^(2+)和HCO_3^-浓度主要受流量影响,对岩溶碳汇通量变化的影响甚微。由此推断,流量是岩溶碳汇通量的主控因素。

The river carbon sink flux is important for the global carbon cycle and finding the missing carbon sink.Hydrogeological features are important parts of the karst dynamic system. In order to analyze the long-term trend and flux changes of river carbon sink,the Wuzhou section of Xijiang that was significantly affected by the wet monsoon climate was selected as the study object. In this paper,the effects of the hydrology and chemistry factors such as flow,water level,rainfall,water temperature,pH,EC,Ca^2＋,HCO3^- of Xijiang river basin from 2011 to 2015 on the river carbon sink flux are discussed. Results show that ① there is a good correlation of river carbon sink flux with the flow and water level（ correlation coefficients 〉0. 95）. The carbon sink flux varies with flow and the good correlation between the carbon sink flux and water level was reflected by the effect of water level on the flow. The rainfall enters a river by different ways,which directly changes the run off in surface and further affects the river carbon sink flux. ② The effect of water temperature on the river carbon sink flux was secondary and related to the climate of summer and monsoon of the Xijiang river basin during the same period. ③ The pH has no obvious effect on the river carbon sink flux because the monitor point water is weakly alkaline. The EC,Ca^2＋ or HCO3^- were mainly affected by flow and have little effect on the carbon sink flux. Therefore,the flow is the most important factor for the carbon sink flux.