土地利用影响下的岩溶地下水水化学变化特征

为了进一步探讨土地利用方式与地下水水质的关系,在湖南湘西峒河流域采集了包括地下水和地表水的131个样品,在室内进行简分析或全分析,并现场测量了水样的p H、温度和电导率。依据土地利用方式和污染来源将峒河流域的岩溶地下水划分为3种类型: 第一类,不受耕地和居民点影响的岩溶地下水;第二类,受耕地但不受居民点影响的岩溶地下水;第三类,受居民点影响的岩溶地下水。将三类岩溶地下水中K+ 、Na+ 、Cl- 、SO2-4 和NO-3 的浓度从大到小放在一个坐标系中比较,结果显示第三类岩溶地下水的5种离子浓度最大,第二类中等,第一类最低,表明土地利用方式对岩溶地下水水质影响明显。在空间分布上,岩溶地下水离子浓度具有东部和东南、西北较高的特点,表现为一些泉水遭到明显的污染,与这些地方土地利用类型以水田、旱地和农村居民点为主,即与农耕施肥和生活垃圾排放有关。虽然居民点或耕地等土地利用类型目前还没有致使地下水水质超过饮用水标准,但是流域内的饮水安全问题不容忽视。 

Hydro-chemical variation of karst groundwater under the impact of land use in Donghe catchment, Hunan

In order to discuss the relationship between land use and groundwater quality further,131 water samples in Donghe catchment were collected and analyzed in the laboratory to determine K ,Na ,Ca2 ,Mg2 ,HCO-3,Cl-,SO2-4,NO-3,etc.Water temperature,pH and electric conductivity were measured in situ.According to land-use type and pollution source,springs were divided into three types,namely,karst groundwater which was not affected by infield and settlement,karst groundwater polluted by infield but not settlement and karst groundwater polluted by settlement.It could be showed that the concentrations of K ,Na , Cl-,SO2-4,NO-3 had a tendency of increase from the first type to the second type and then to the third one,indicating that land use had a distinct impact on groundwater quality.For the spatial distribution,concentrations of these ions were higher in the east,southeast and northwest parts,representing some springs had suffered from evident pollution.The land-use types in these regions were mostly paddy field,dry land and village,showing that springs there were easily affected by fertilizer and consumer waste.The two springs in Liuxinpo and Tongmuzhai respectively could represent the impact of land use on hydro-chemistry obviously.They had same geological condition but different land-use types,leading to difference in hydro-chemistry.Although rural settlements and cultivated land had not made the groundwater undrinkable at present,the problem of rural drinking water safety should not be ignored at any time.