Hydrochemical properties and groundwater quality evaluation in Suzhou City, lower Yangtze Delta, China

Abstract

Detailed study of the chemical analysis results of 49 groundwater samples collected from the region’s second confined aquifer were carried out in an attempt to identify the samples’ hydrochemical properties and to assess the quality and usability of groundwater in Suzhou city, China. The results revealed that sodium, calcium and bicarbonate were the dominant ions in the groundwater samples. Na-HCO3, mixed Na-Ca-HCO3, Ca-HCO3, and Na-Cl type were the four major hydrochemical facies identified by a Piper Trilinear diagram. It was observed that the concentration of ammonia and nitrite in most of the samples in study area exceeded the permissible limit values prescribed by the national (China) and international (WHO) drinking water guidelines. Anthropogenic activities have been shown to be largely responsible for groundwater contamination. Scatter diagrams and factor analysis suggest that natural weathering processes, along with anthropogenic activities, control the hydrogeochemistry of groundwater. On the basis of the analytical results of the 49 groundwater samples as compared to water quality standards, it was found that majority of groundwater samples were not suitable for drinking or for industrial uses directly. Toxic metals and high levels of ions must be removed to render the groundwater suitable for drinking and industrial purposes. However, salinity, sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and sodium percentage (Na%) values indicate that most of groundwater samples were suitable for irrigation purposes.