Characteristics of the content and distribution of heavy metals in groundwater in Mashan area, middle to lower Hongshui River, Guangxi, China

Based on the groundwater data obtained from the karst groundwater and information gained from the groundwater pollution investigation and evaluation in the southwest China, this work analyzes geochemical characteristics of 10 heavy metals with 27 karst groundwater samples collected in Mashan area located in the middle to lower Honghe River. The main focus of this study is to establish a relationship between the concentrations of heavy metals and their spatial distribution and the other chemical constituents dissolved in the karst groundwater, as well as the relationship between the heavy metals studied. The results indicate that the concentration of heavy metals is lower than the upper limit for drinking water standard of China, and the contents of heavy metals in the groundwater follows a descending order as Fe＞Al＞Zn＞Mn＞Pb＞Se＞As＞Cd. There is a remarkably positive correlation between Mn, Fe, As and Al, and a significant positive correlation between Zn and Pb, Cd in the groundwater as well. The relationship between Se and other seven heavy metals is not that apparent, perhaps due to the diversity of the heavy metal sources. All the heavy elements have no correlation with pH, whereas the chemical contents HCO3-, Ca2+and HCO3-have a great impact on the heavy metal concentrations. TDS has little effect on most of the heavy metals, but a certain effect on the appearance of As and Cd. In terms of spatial distribution of the heavy metals, the localities with high concentrations mainly occur in and around the city Mashan and townships in the vicinity of Guzhai and Qiaolijie.