Selenium in groundwater and its contribution towards daily dietary Se intake under different hydrogeological zones of Punjab, India

Summary More than 750 groundwater samples collected from different hydrological zones of Punjab state in India were analysed for selenium and some quality parameters to determine suitability of groundwater for irrigation and drinking purpose. Selenium content varied from 0.01 to 35.6 μg L −1 . Average Se content in groundwater was the highest in Northeastern Siwalik foothill zone (NSFZ) followed by Central zone (CZ) and Southwestern zone (SWZ). Majority of the water samples contained −1 – the safe limit for drinking purpose except one location each in SWZ and CZ and three locations in NSFZ. Only at one location, water contained >20 μg Se L −1 which is considered unsuitable for irrigation of crops. On the basis of pH, 42% of the samples were unfit for drinking in SWZ, 41% in CZ and 6% in NSFZ. Only in SWZ, 24% of the samples with high total dissolved salts were unfit for drinking and 18% unfit for irrigation purpose due to high EC. Selenium content in groundwater was inversely related to depth of water and the degree of relationship was higher for NSFZ ( r  = −0.342 ∗∗ ) followed by CZ ( r  = −0.157 ∗ ) and SWZ ( r  = −0.126 ∗ ). Depending on the amount of water consumed from 2 to 5 L, average Se intake varied from 1.66 to 6.39 μg d −1 and its contribution towards the recommended daily Se allowance ranged from 3.0% to 11.6% for women and 2.4% to 9.1% for men. Among the grain samples, 94% of wheat and 46% of rice contained Se above the deficiency limit of 100 μg kg −1 . Thus, the residents in the study area primarily consuming wheat grains and drinking groundwater are getting adequate supply of Se. Among the materials tested for decreasing Se from drinking waters, scrap iron fillings showed potential for commercial use.