再生水补给河道入渗区地下水水质时空变异分析

运用聚类分析、判别分析和主成分/因子分析方法来研究潮白河流域再生水补水河段地下水水质的时空变异情况。对地下水进行剖面分析（剖面A为平行于水流场方向，剖面B垂直于水流场方向）。地下水研究结果表明除NO3-、NH4+和Mn2+外，其余指标均达到地表水Ⅱ类标准。剖面A的季节判别中由于淋溶作用筛选出pH和TDS，正确率为77.5%，说明研究区在近岸区。同时，剖面B的季节变异由于远离河岸的土壤蓄水层中氧化还原作用使得Fe3+、Mn2+、Na+、NO2-、CODMn和TP被判别出，正确率为74.4%。此外，由于非冻土期土壤蓄水层中频繁的淋溶作用和活跃的生化反应识别出CODMn、HCO3-、NO2-、pH、SO42-、Cl-、Na+和Ba2+表征了非冻土期剖面A的空间变异，而判别正确率为100%的F-、Na+和HCO3-则表征了冻土期剖面A的空间变异。冻土期剖面B的TDS和TP以及非冻土期剖面B的TN和K+的判别正确率均为100%。再生水对近岸带的影响较远岸带显著。该分析结论可归因于再生水的污染、土壤蓄水层矿物盐岩溶解污染、工农业废水排放的点源污染和降水及流域水土流失所造成的非点源污染的综合作用。

Multivariate statistical analysis of temporal-spatial variations in ground water quality of urban riverways

Variations in the quality of ground water near reclaimed water (RW) supplement that reach the Chaobai River were described via cluster analysis (CA), discriminant analysis (DA), and principal component analysis/factor analysis (PCA/FA). Ground water profiles (with profile A along the flow and profile B vertical to the flow) were analyzed. Ground water results demonstrated a relatively satisfactory water quality, except for NO3-, NH4+, and Mn2+, pH and thermal desorption spectroscopy (TDS) caused 77.5% of temporal variations in profile because of leaching, which dominated areas near the riparian zone (RZ). Meanwhile, Fe3+, Mn2+, Na+, NO2-, CODMn and TP caused 74.4% of temporal variations in profile B because of oxidation-reduction process in soil aquifer far from the riparian zone (FRZ). Additionally, CODMn, HCO3-, NO2-, pH, SO42-, Cl-, Na+ and Ba2+ caused 100% of non-frozen soil period (NFP) spatial variation of profile A because of frequent leaching and active biochemical reaction in soil aquifer during NFP, whereas only F-, Na+, and HCO3- caused 100% of frozen soil period (FP) spatial variation of profile A. TDS and TP were selected for FP, whereas TN and K+ were selected for NFP, both with 100% accuracies. The effect of RW on the RZ was more significant than that on the NRZ. This finding could be due to the combination of RW pollution, mineral rock dissolution pollution from soil aquifer, point pollution of domestic and industrial wastewaters, and non-point pollution of rainfall and soil erosion from watersheds.