Assessment of Radioactive Materials and Heavy Metals in the Surface Soil around the Bayanwula Prospective Uranium Mining Area in China

Abstract

The present work is the first systematic and large scale study on radioactive materials and heavy metals in surface soil around the Bayanwula prospective uranium mining area in China. In this work, both natural and anthropogenic radionuclides and heavy metals in 48 surface soil samples were analyzed using High Purity Germanium (HPGe) γ spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS). The obtained mean activity concentrations of 238U, 226Ra, 232Th, 40K, and 137Cs were 25.81 ± 9.58, 24.85 ± 2.77, 29.40 ± 3.14, 923.0 ± 47.2, and 5.64 ± 4.56 Bq/kg, respectively. The estimated average absorbed dose rate and annual effective dose rate were 76.7 ± 3.1 nGy/h and 83.1 ± 3.8 μSv, respectively. The radium equivalent activity, external hazard index, and internal hazard index were also calculated, and their mean values were within the acceptable limits. The estimated lifetime cancer risk was 3.2 × 10−4/Sv. The heavy metal contents of Cr, Ni, Cu, Zn, As, Cd, and Pb from the surface soil samples were measured and their health risks were then assessed. The concentrations of all heavy metals were much lower than the average backgrounds in China except for lead which was about three times higher than that of China’s mean. The non-cancer and cancer risks from the heavy metals were estimated, which are all within the acceptable ranges. In addition, the correlations between the radionuclides and the heavy metals in surface soil samples were determined by the Pearson linear coefficient. Strong positive correlations between radionuclides and the heavy metals at the 0.01 significance level were found. In conclusion, the contents of radionuclides and heavy metals in surface soil around the Bayanwula prospective uranium mining area are at a normal level.

Distribution and Multivariate Pollution Risks Assessment of Heavy Metals and Natural Radionuclides Around Abandoned Iron-Ore Mines in North Central Nigeria

“…The hazard index HI is defined as the total sum of HQ obtained for different pathways as shown in Eq. (8) (Xu et al 2013, Bai et al 2017):…”

“…If HI > 1.0, noncarcinogenic health risk is probable and the risk increases with increase in HI (Bleam 2016;Bai et al 2017).…”

“…For non-cancer risk, the values of the hazard indices due to heavy metals rock samples are more pronounced than those for soil samples. For cancer risk, only Ni, Cr, Cd, Co and As were considered (Bai et al 2017). The cancer risks obtained for the five heavy metals in rock and soil dusts are much lower than the acceptable upper limit of 10 −4 .…”

“…Strong positive correlations between heavy metals or radionuclides suggest similarity in origin, transfer mechanism or behavior in the environment. The absence of correlations implies that the heavy metals or radionuclides are mutually independent or differ in behavior (Bai et al 2017). …”

“…Long-term exposure to and inhalation of heavy metals and natural radionuclides could cause many health problems, such as acute leukemia, anemia, cataracts of the eye as well as different types of cancer (Taskin et al 2009;Qureshi et al 2014;Wang et al 2017). Several researchers have made efforts to correlate heavy metal contamination with natural radioactivity in soil and water (Baykara and Dogru 2010;Meindinyo and Agbalagba 2012;Faisal et al 2015;Milenkovic et al 2015;Chen et al 2015), aquatic environment (Szarlowicz et al 2013;Aytas et al 2014;Goher et al 2014;El-Amier et al 2017), crude oil (Ajayi et al 2009), fertilizer (El-Taher and Althoyaib 2012), uranium and phosphate mining areas (Atta et al 2016;Bai et al 2017), other mining environment (Mileusnic et al 2014), etc. Information on such efforts concerning iron-ore mines is very scanty.…”