Multivariate statistical study on naturally occurring radioactive materials and radiation hazards in lakes around a Chinese petroleum industrial area

Abstract

The high-purity germanium gamma-ray spectrometer was used to measure the radioisotope in surface water of lakes in a Chinee petroleum industrial area. 92 samples were collected from surface water of three lakes. Activity concentrations of 232Th, 226Ra and 40K in three lakes were measured, distributed in the range of 101.8–209.4, 192.1–224.9 and 335.0–548.9 mBq/L, respectively. Results were all within the limits of WHO and China. Potential environmental and health risks were assessed by calculating some radiation hazard indicators, radium equivalent index, annual effective dose, excess lifetime cancer risk, absorbed dose rate, external hazard index, internal hazard index, annual gonadal dose equivalent, activity utilization index and representative gamma index, which ranged 0.38–0.54 Bq/L, 0.06–0.08 mSv/y, 0.23 × 10−3-0.31 × 10−3, 0.17–0.24 nGy/h, 1.01 × 10−3-1.46 × 10−3, 1.55 × 10−3-2.02 × 10−3, 1.16–1.66 μSv/y, 3.13 × 10−3-4.45 × 10−3 and 2.60 × 10−3-3.77 × 10−3. The results were all at acceptable levels, meaning no impact on human health. The relationship between the electrical conductivity of surface water and the activity concentration of 232Th, 226Ra and 40K was evaluated. The electrical conductivity value was 0.241–0.369 mS/cm, showing a significant correlation coefficient between 226Ra and 40K and electrical conductivity. Multivariate statistical methods were used to determine the relationship between the activity concentrations of 232Th, 226Ra, and 40K, radiation hazard indicators and electrical conductivity.

Keywords

• Surface water
• Multivariate statistical analysis
• Radioactivity
• radiation hazards
• Petroleum industry