Skip to main content
. 2021 Nov 11;18(22):11805. doi: 10.3390/ijerph182211805

Figure 2.

Figure 2

The box plots of δ18O values of NO3− from different sources. Note: (1) data source: literature [59,60,61,62,63,64,65,66,67,68,69,70,71,77,78,79,80,81], sample number: atmospheric deposition NO3−: n = 40; nitrification: n = 36; NO3− fertilizer: n = 15.