三峡库区典型农田小流域水化学特征及变化规律

Water chemistry characteristics of a typical agricultural small watershed in Three Gorge Reservoir area and its changing tendency

以三峡库区典型农田小流域—涪陵王家沟小流域为代表,通过对流域内水体主要离子组成的系统监测,分析了该流域的水化学特征和主要离子组成变化规律.结果表明,Ca2+、Cl-分别是该流域的优势阳离子和优势阴离子,流域属淡水,水质为氯化物水体,即ClCaⅢ型,水化学类型为Cl-—Ca2+型;TZ+(总阳离子当量浓度)为6.30meq/L,高于世界平均水平,TZ-(总阴离子当量浓度)为6.29meq/L;TDS(总溶解固体)平均值为294.78mg/L,显示了该流域剧烈的化学侵蚀作用;大多数离子的含量随采样点、季节、水体类型的不同而有显著性差异.

Through systematically monitoring the ion compositions of the water bodies,a case study has been conducted in a typical agricultural small watershed-Wang Jiagou Small Watershed,which is located in Three Gorges Reservoir areas,Chongqing,for understanding the characteristics of its water chemistry and the changing tendency,The results showed that Ca2＋ and Cl-were predominant cation and anion respectively,waters in the watershed were of fresh water,and the water quality belonged to Cl--Ca2＋ type classified as ClCaⅢ type.Meanwhile,it＇s also found that TZ＋ was 6.30meq/L,which highly exceeded the world average level,and TZ-was accordingly 6.29meq/L.Additionally,the average TDS was 294.78mg/L,indicating the existence of significant chemical erosion process.Furthermore,for most ions among different sampling points,the significant variations of ions contents were also observed due to seasons and water types.