WATER QUALITY, HYDROCHEMICAL PROCESSES AND SOURCE APPORTIONMENT OF SHALLOW GROUNDWATER IN URBAN-RURAL FRINGE SUZHOU CITY CHINA

Thirty two groundwater samples were collected in urban-rural fringe, Suzhou City, China to delineate the hydrochemical processes, identify the ion source, and appraise the drinking and irrigation water quality. The results show that the order of abundance of the ions is as follow: HCO3->Na+>Ca2+>Mg2+>SO42->Cl- . HCO3- and Na+ are the dominant component for anions and cations, respectively. The Durov diagram identified three types of hydrochemical facies containing Na-HCO3, Ca-HCO3, and Mg-HCO3. The hydrogen-oxygen isotopes analysis indicates the atmospheric precipitation plays an obvious role in the origin of the groundwater samples, and some samples have undergone evaporation before being infiltrated to the aquifer. Gibbs diagram reflect the water-rock interaction is the prominent process. The bivariate plots of HCO3/Na versus Ca/Na, and Mg/Na versus Ca/Na and the ion ratio analysis, combined with principal component analysis (PCA), and the Unmix model analysis illustrate that the dissolution of halite, the dissolution of sulfate, the weathering of silicate, and the cation exchange are the main undergoing hydrochemical processes. Water quality index (WQI) suggest that thirty samples accounting for 93.75% were classified into good water quality category, two samples accounting for 6.25% were categorized as poor water quality. The USSL diagram shows that 65.62% of the samples fall in the C2S1 category and 34.38% of the samples are in C3S1 category. The Wilcoxdiagramindicates that 21 samples belong to the excellent to good category, 11 samples fall under the good to permissible category, and these samples can be applied to irrigate salt-tolerant and semi-tolerant crops under favorable drainage conditions.