Fig. 3. Distributions in all ground water samples from each site of (A) average age with mixing (piston flow ages shown for Maryland, where mixed ages were not calculated), (B) piston flow age, (C) dissolved O₂, (D) denitrification progress (proportion of initial nitrate in ground water subsequently converted to N₂, _denit in Eq. [4]), and (E) NO₃^–. Error bars show the minimum and maximum values, boxes show the interquartile range, and horizontal lines inside the boxes show the median.