Mohammad Khanizadeh

Anthropogenic activities such as uranium mining, coal ash disposal, and phosphate fertilizers utilization can further enhance uranium mobilization in the environment. This systematic review investigated the uranium (U) concentration in world water sources with a meta-analysis assessment. A search strategy was done in PubMed, Science Direct, Web of Science, Google Scholar databases, and gray literature, and 46 records were included. Heterogeneity among the studies was assessed using the I 2 statistic and Cochran's chi-square test. Funnel curve asymmetry was evaluated by Egger's regression asymmetry test. Sensitivity analysis was conducted to specify the robustness of the findings. The uranium mean concentration in water sources was 0.15 μg/L (0.13-0.16), and mean of uranium in groundwater and surface water was 0.17 (0.13, 0.21), 0.19 (0.13, 0.25), 0.14 (0.12, 0.16), 0.16 (0.12, 0.20), 0.14 (0.12, 0.16), 0.13 (0.09, 0.17), 0.15 (0.13, 0.16), and I 2 = 8 %, 0.09 (0.03, 0.15), 0.29 (0.11, 0.47), 0.17 (0.02, 0.36), and I 2 = 77.5 % respectively. The concentration of uranium in water sources varies significantly across different countries, with the maximum concentration detected in surface water from South Africa (0.29 μg/L) and the minimum in groundwater from the USA (0.01 μg/L). The meta-regression test also indicated that the number of samples, the sampling area, and the publication year did not affect the heterogeneity between the studies. The results of subgrouping based on the water source showed that the surface water affected the heterogeneity value.