A 10-Year Statistical Analysis of Heavy Metals in River and Sediment in Hengyang Segment, Xiangjiang River Basin, China

Heavy metal elements in water and surface sediments were characterized in Hengyang river segment in Xiangjiang River basin, one of China's most important heavy metal control and treatment region. Data of heavy metal monitoring results in water and sediment for 10 years were acquired from an environmental monitoring program in the main channel of the studied area. Descriptive and exploratory statistical procedures were performed to reveal the characteristics of the sample distributions of heavy metal elements. The sample distributions of heavy metal elements were largely skewed right. Data censoring and too severe rounding in the water monitoring data were identified to have caused discretization in the sample distributions. Temporal and spatial characteristics of the data sets were addressed. The chromium (Cr) in the sediment possessed unique behavior, and this could be caused by a rapid deposition and releasing process.