Figure 3: Δ17O-NO3− versus δ15N-NO3− of Uinta Mountain water samples relative to possible sources. | Nature Communications

Figure 3: Δ17O-NO3− versus δ15N-NO3− of Uinta Mountain water samples relative to possible sources.

From: Agriculture causes nitrate fertilization of remote alpine lakes

Figure 3

The SIAR model inputs for nitrate sources are represented by the blue and grey boxes. The lines shown below the x axis (δ15N) indicate source N isotopic ranges (see also Supplementary Table 2). The overlap in source values for δ15N (NH4+ & NO3− Fertilizer+Rain NH4+, Soil NO3− and Septic Effluent and Manure) is shown by the overlap of lines below the x axis. Model inputs for the nitrate sources are drawn from the literature21 other than for AON, which was derived from the mean and s.d. of the Uinta Mountain snow samples. Samples plotting above terrestrial source Δ17O (0±1‰) contain a significant contribution from AON.

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