岩溶地下河系统在无雨条件下,秋季短时间尺度(10日左右)内其出口处水化学动态具有显著的日周期,连续功率谱及交叉功率谱分析可以识别这一周期。文章以茂兰自然保护区板寨地下河系统出口为研究对象,运用频谱分析方法对2007年10月中旬无雨条件下10日左右连续监测的气象要素、水化学数据进行研究,发现植被覆盖良好的岩溶地下河系统,出口处水化学动态呈现日动态变化周期,表现为白天气温升高,水的pH值升高,二氧化碳分压、电导率和方解石饱和指数降低,其中pH值对气象要素的响应最为敏感,二氧化碳分压对水温的响应最为敏感。
In normal days of no rainfall, the hydrochemical variation of the exit of a karst ground river system has a remarkable diurnal periodicity on a short time scale (about 10 days) and the periodicity can be identified using continuous power spectrum analysis and cross spectrum analysis. In this article, taking the outlet of the Banzhai karst ground river system in the Maolan Nature Reserve as an example and using the method of spectrum analysis, the authors investigate the data of meteorological factors and hydrochemistry which were continuously monitored for about ten days of no rainfall in the middle October in 2007. The results indicate that the hydrochemieal variation of outlet of the karst ground river system covered with virgin forest shows a remarkable diurnal periodicity. The water pH rose, whereas CO2 partial pressure, electric conductivity and calcite saturation index drop during daytime when the air temperature rose. The response of water pH to meteorological factors and the response of CO2 partial pressure to water temperature are most sensitive.