High levels of molybdenum in Qatar's groundwater and potential impacts

• Qatar faces serious challenge on deterioration of groundwater quality & quantity.
• Limited global emphasis is placed on molybdenum (Mo) in groundwater (GW).
• The study emphasizes that elevated Mo in GW may be a global phenomenon.
• Results call for more studies on Mo to address potential health risks of exposure.

Similar to other arid nations, Qatar's aquifers are highly susceptible to contamination due to overexploitation and rapid industrialization creating conditions of vulnerability for local environments and populations. This study quantified physicochemical properties, cations, anions, organic carbon and trace element content in 205 samples of Qatar's groundwater. Elevated Mo (mean = 26.9 μg/L; max = 103 μg/L) was observed throughout Qatar, along with localized clusters of elevated Cd (max = 8.67 μg/L), As (71.6 μg/L), Pb (37.1 μg/L) and Se (80.1 μg/L) indicating spatial distribution of these contaminants. Groundwater was brackish to saline (25th–75th percentile TDS = 2140–4660 mg/L); SAR (mean = 10.1) and EC (mean = 7250 μS/cm) values indicate continued use of Qatar's groundwater for irrigation may compromise soil structure and crop yield. Limited global emphasis is placed on Mo in groundwater; however, localized regions of the world exhibit elevated Mo, including Qatar. Compared to the studies in other parts of the world, our study serves to emphasize that elevated levels of Mo in groundwater may be a global phenomenon and calls for further studies to address potential health risks of exposure.