云南开远南洞地下河水质演变特征

Changing features of water quality in the Nandong underground river,Kaiyuan,Yunnan

在云南开远南洞地下河出口,连续19年采取旱、雨季水样进行水质变化监测,结果表明:(1)整体上地下水水质旱季好于雨季,历年旱季水质类型以良好为主,雨季则以较差为主;(2)水质变化阶段性明显:1987—1993年,离子浓度普遍较低,旱、雨季波动不大,水质多属、类,有机污染以NH+4、NO-3等为主;1994—2000年,旱、雨季离子浓度均普遍升高且变化加剧,NH+4、As、Cd、Cr、Mn出现历年最大值,金属离子污染日趋加剧,水质以、类为主;2001—2005年,旱、雨季离子浓度有升有降,以升为主,Pb、Zn、Cl-、SO42-出现历年最大值,水质以、类为主。南洞地下河水质19年来发生了较大的变化,污染日趋严重。分析认为该地下河水质逐步变差与上游补给区盆地内经济发展状况密切相关。为此,提出了采用自动监测等方法加强地下河动态变化监测研究以及实行分区、分级管理等水质保护的具体对策建议。

The Nandong underground river system is large in scale and complex in structure. The results from continuous monitoring of water quality data taken from both dry and rainy reason each year from 1987 to 2005 at the outlet of the Nandong underground stream show that the chemical concentration of the ground- water has three distinct periodic features, and tends to increase overall and the value in rainy season is higher than that in dry season generally. From 1987 to 1993,the ion concentration was relatively low with a slightly change between dry and rainy season, and water quality chiefly belonged to class Ⅰ or Ⅱ, and the polluted chemical material mainly included NH4^＋ and NO3^-. From 1994 to 2000,the ion concentration value usually was raised with a intensive change between dry and rainy season, and water quality degraded to class Ⅱ or Ⅲ, and the metallic pollution appeared with the content of Cd, Cr, Mn reached to a maximum all over the years. From 2001 to 2005,the ion concentration value fluctuated with a trend of increase during dry and rainy season, while water quality remained in class Ⅱ and Ⅲ, and the content of Pb, Zn, Cl^-, SO4^2- reached a maximum over the years. Generally, the water quality in dry season is better than that in rainy season. The water quality has great changes and been deteriorated and contaminated gradually over 19 years mainly due to economic development in the basin at the upper reaches of the catchment. Concrete countermeasures such as au- tomatic monitoring to underground river and actual management through partition and classification have been put forward finally.