Radionuclides distribution characteristic in sediment profiles of a uranium smelting in Guangdong, South China

In order to study the radionuclides vertical distribution of the sediments downstream from the uranium smelting in Guangdong, the contents of 238U, 235U, 226Ra, 232Th and 40K were measured in pond sediment, river sediments, and paddy soil profiles using HPGe-γ ray spectrometer. The 238U, 235U and 226Ra pollution were serious in the pond sediments > stream sediment > paddy soil, while those of 232Th and 40K changed a little. Radionuclides contents are relatively low in paddy soil, since the rice fields were not irrigated by water downstream from the uranium smelting. The contents of 238U, 235U and 226Ra were higher in the pond sediments than those of the paddy soil by about 100, 87, and 155 times, respectively. The contents of 238U, 235U, and 226Ra were increased with the vertical depth of sediment samples. The highest content was about 40 cm in depth. The 238U, 235U and 226Ra contents increased with stream sediment depth, and its contents positively correlated with organic matter content in the sediments.