Radiological hazard in the sediment of the Xining section of the Huangshui River, China

Natural radioactivity was determined in sediment samples collected from the Xining section of the Huangshui River in northwest China. The activity concentrations of 226 Ra, 232 Th and 40 K in the sediment samples range from 15.8 to 65.3, 24.3 to 86.0 and 432.6 to 702.4 Bq.kg-1 with an average of 32.4, 43.0 and 527.5 Bq.kg-1 , respectively. All investigated sediment samples have radium equivalent activity lower than the limit of 370 Bq.kg-1 and an external hazard index less than unity. The mean outdoor air absorbed dose rate is 63.5 nGy.h-1 and the corresponding outdoor annual effective dose rate is 0.078 mSv.y-1 . The radiation level of the studied location is safe, and the sediment can be safely used in construction according to the current norms.