广州市沿海地区浅层地下水质量评价

Evaluation of Shallow Groundwater Quality in Coastal Area of Guangzhou

基于研究区18个地下水采样点近2 a的监测结果,采用单指标综合评价法和主成分分析法对研究区地下水质量进行了评价,并探讨了水质变化的影响因素。结果表明:研究区浅层地下水质量总体较差,但近两年有变好的趋势。研究区超标指标主要有氨氮、锰、耗氧量、氯化物、总硬度、溶解性总固体、铁、pH值和硫酸盐等9项,超标率在23.6%~77.8%之间。从时间上看,该区域浅层地下水质量雨季略优于旱季;从空间上来看,区域内各分区的浅层地下水质量互有优劣。地下水水质的影响因素较多,其中氯化物、总硬度、溶解性总固体和硫酸盐等盐分指标主要受海水影响,铁、锰等重金属指标主要受氧化还原环境影响,pH值同时受酸雨和海水影响,氨氮主要受农业面源污染和生活污水影响,耗氧量主要与受污染的地表水有关。

Based on the monitoring results of 18 groundwater sampling points in the study area in recent two years,the groundwater quality in the study area was evaluated by single index comprehensive evaluation method and principal component analysis method,and the influencing factors of water quality change were discussed.The results show that the quality of shallow groundwater in the study area is generally poor,but it tends to be better in recent two years.In the study area,the over standard indexes mainly include ammonia nitrogen,manganese,oxygen consumption,chloride,total hardness,total dissolved solids,iron,pH value and sulfate,with the exceeding rate of 23.6%~77.8%.In terms of time,the quality of groundwater in rainy season is slightly better than that in dry season;in terms of space,the quality of groundwater in each region is good or bad.There are many factors affecting groundwater quality,among which chloride,total hardness,dissolved total solid and sulfate are mainly affected by seawater;iron,manganese and other heavy metal indicators are mainly affected by redox environment;pH value is affected by acid rain and seawater;ammonia nitrogen is mainly affected by agricultural non-point source pollution and domestic sewage;oxygen consumption is mainly related to polluted surface water.