Multidimensional pollution and potential ecological and health risk assessments of radionuclides and metals in the surface soils of a uranium mine in East China

PURPOSE: Pollution from long-lived radionuclides coupled with metals and metalloids (MMs) in uranium mines is globally considered a primary environmental concern. However, research on this topic has been limited to uncovering the ecological and human health risks of this combined pollution in uranium mines. MATERIALS AND METHODS: A total of 120 surface soil samples were collected from 40 sampling sites at a uranium mine in East China. The health hazards of the natural radionuclides were evaluated according to their absorbed dose rate, radium equivalent, hazard indices, annual effective dose equivalent, and excess lifetime cancer risk. Moreover, the contamination statuses and potential ecological and health risks to children and adults through different MM exposure routes were revealed using the geo-accumulation index (Igₑₒ), contamination factor (Cf), pollution loading index (PLI), potential ecological risk index (RI), and US EPA health risk assessment models. The interactions between potential ecological and health risks were shown by using the regression fitting method, and the Pearson correlations between the radionuclides and MM were also calculated. RESULTS AND DISCUSSION: Results showed that only the average activity concentration of the radionuclide ⁴⁰K was much higher than the global average, but the health hazard and radiological parameters were within acceptable levels. The average Cd content was 1.6 times the local background value and slightly less than that of grade I in the Chinese soil quality guidelines, which posed potential ecological risks to the study area, although other MMs were present at levels lower than both of the reference values. The Igₑₒ, Cf, PLI, and RI results suggested that the contamination around the uranium facilities was more serious than at other sampling sites. Health risk assessments showed that ingestion was the primary route for the metals to enter the human body and threaten human health. The carcinogenic risk from Ni and As to children and adults was the primary health concern in the study area. Moreover, the children were potentially under higher carcinogenic risk than the adults. The correlation analyses between potential ecological and health risks showed that the compatibility between the RI and HIA, HIC, or CRC, respectively, was acceptable when applied in the study area. Strong positive correlations were also found between the ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K, ¹³⁷Cs, Cu, As, and Ni. CONCLUSIONS: Pollution from long-lived radionuclides and their associated MMs has posed potential ecological risks to the ecosystem and caused human carcinogenic risk in the study area.