Estimation of uranium in groundwater and assessment of age‑dependent radiation dose in Nalbari district of Assam, India

摘要

Uranium concentration has been estimated in 31 groundwater samples collected from the Nalbari district of Assam inpre-monsoon and post-monsoon season. Fourteen other water quality parameters have also been monitored to studytheir correlation with uranium. The uranium concentration varies from 0.3 to 7.1 μg/L with the mean value of 2.15 μg/Lin pre-monsoon and 0.6–10.3 μg/L with the mean value of 2.75 μg/L in the post-monsoon season. The higher concentrationof uranium in post-monsoon may be ascribed to the dissolution of uranium from soil sediments in the rainy season.It has been observed that the uranium content in both seasons is far lower than the WHO (2011) permissible limit of 30μg/L. In both seasons, nitrate, sulphate, and especially phosphate show a positive correlation with uranium, which maybe due to different agricultural activities. Agricultural nitrate and phosphate fertilization might be the carrier of uraniumin groundwater through dissolution. For all life stage groups, the annual effective dose was appeared to be far belowthe WHO (2011) prescribed limit of 100 μSv/y. In consideration to adults, the ingestion dose for infants was turned out tobe higher. The carcinogenic and non-carcinogenic risk was less than the permissible limits for both children and adults.Both dose value and risk indices were found higher in the post-monsoon season.