科尔沁沙地奈曼地区地下水水质时空变化特征

Spatial and Temporal Variability Analysis of Groundwater Quality in Naiman Region of Horqin Sandy Land

区域地下水水质是水质评价的重要内容,也是合理制定地下水开发利用及保护治理方案的基本前提。以科尔沁沙地奈曼地区地下水水质为研究对象,选取2005—2014年地下水水质监测数据,分析地下水水质时空变化特征。结果表明:近10年来奈曼地区地下水水质各指标均值均低于地下水Ⅱ类标准,pH值、NO_3^-含量、化学需氧量(CODcr)在局部地区出现超标现象,但水质总体较好;该地区地下水矿化度(TDS)与Ca^(2+)、Mg^(2+)、Na^+、HCO_3^-、SO_4^(2-)浓度及COD_(cr)具有明显的正相关关系,即随着Ca^(2+)、Mg^(2+)、Na^+、HCO_3^-、SO_4^(2-)、CODcr浓度的增加,TDS也会增加;各主要指标浓度随时间呈下降趋势,SO_4^(2-)、Na^+、HCO_3^-浓度及TDS较稳定,而Ca^(2+)、Mg^(2+)、Cl^-、PO_4^(3-)浓度及COD_(cr)随时间变化较为明显;Ca^(2+)、Mg^(2+)、HCO_3^-、SO_4^(2-)浓度及TDS农田非灌溉井>农田灌溉井>沙地水位井,Na^+、CODcr浓度沙地水位井>农田非灌溉井>农田灌溉井,NO_3^-浓度沙地水位井>农田灌溉井>农田非灌溉井;该地区地下水水质变化主要与碳酸盐岩溶解、农药化肥的使用、工业及生活污水排放有关。

Research on spatial and temporal variability of regional groundwater quality is not only an impor- tant content of water quality evaluation, but also is the basic and premise for management decisions of groundwater utilization and protection. In this study, the 10-years data of groundwater quality from 2005 to 2014 were used to analyze the spatial and temporal variability of groundwater quality in Naiman region of Horqin Sandy Land. The results showed that the 10-years average value of each index was lower than na- tional groundwater quality Ⅱ class standards, but pH.NO3- and CODcr exceeded national groundwater Ⅱ class standard in some areas, in general, the water quality in this region was better. There were an obvious posi- tive correlation between the regional TDS with Ca2＋, Mg2＋, Na＋, HCO3-, SO2-4, CODcr, additionally, TDS increased with increasing Ca2＋, Mg2＋, Na＋, HCO3-, SO2- 4 , CODer, the concentration of major water quality index were on the decline over time, SO2-4, Na＋, TDS, HCO3- were relatively stable over time, but Ca2＋, NO3-, Mg2＋, Cl-, PO3-4, CODer had significant changes during the 10-years period. The concentration of Ca2＋, Mg2＋, HCO3-, SO2-4, TDS were the sequence of farmland non-irrigation well.farmland irrigation well〉sand gauging well, Na＋, CODcr were the sequence of sand gauging well.farmland non-irrigation well 〉farmland irrigation well, NO/was the sequence of sand gauging well〉farmland irrigation well〉farmland non-irrigation well. The changes of groundwater quality in this area mainly depend on the carbonate karst solution, the pesticides and fertilizers utilization, and the industrial and living sewage discharge.