Reconstruction of the Cadmium Contamination History of a River Floodplain from Maoniuping Mining Area (China) by Gamma Ray Spectrometry and Inductively Coupled Plasma Mass Spectrometry

The Maoniuping rare earth elements deposit is the second largest rare earth elements deposit in China, and the third largest in the world. A sediment core was collected from the river floodplain downstream from the Maoniuping rare earth elements mining area (Sichuan Province, China) to reconstruct the cadmium contamination history and trace its contamination source. Based on lead-210 (²¹⁰Pb) dating by gamma ray spectrometry and elements determination with inductively coupled plasma mass spectrometry of the sediment core, it was found that the cadmium accumulation rate of the flood plain increased from 0.16 to 2.22 µg cm^?2 yr^?1 over the past 100 years. Combining aspects of time, space, and element composition information, it is proved that the exploitation of Maoniuping rare earth elements deposit was the main reason for the increase. Moreover, to evaluate the mobility and availability of cadmium in the sediment core, the modified European Communities Bureau of Reference sequential extraction procedure in combination with inductively coupled plasma mass spectrometry was applied. Risk assessment code was used to further assess the environmental risk of cadmium in the sediment. It was found that the environmental risk from cadmium was high in the surface of the sediments. The results from gamma ray spectrometric and mass spectrometric methods may provide important information for the control and remedy of cadmium-related pollution areas.