The stable isotopic compositions of nitrate dissolved in 49 types of bottled drinkingwater collected worldwide were determined, to trace the fate of atmospheric nitrate(NO−3 atm) that had been deposited into subaerial ecosystems, using the17O anomalies(∆175 O) of nitrate as tracers. The use of bottled water enables collection of groundwaterrecharged at natural, background watersheds. The nitrate in groundwater had small∆17O values ranging from −0.2 ‰ to +4.5 ‰ (n = 49). The average ∆17O value andaverage mixing ratio of atmospheric nitrate to total nitrate in the groundwater sampleswere estimated to be 0.8 ‰ and 3.1 %, respectively. These findings indicated that the10 majority of atmospheric nitrate had undergone biological processing before being exported from the surface ecosystem to the groundwater. Moreover, the concentrations ofatmospheric nitrate were estimated to range from less than 0.1 µmol l−1to 8.5 µmol l−1,with higher NO−3 atm concentrations being obtained for those recharged in rocky, arid orelevated areas with little vegetation and lower NO−3 atm concentrations being obtained15 for those recharged in forested areas with high levels of vegetation. Additionally, manyof the NO−3 atm-depleted samples were characterized by elevated δ15N values of morethan +10 ‰. Uptake by plants and/or microbes in forested soils subsequent to deposition and the progress of denitrification within groundwater likely plays a significant rolein the removal of NO−3 atm.