Tracing the Origin of Groundwater Nitrate in an Area Affected by Acid Rain Using Dual Isotopic Composition of Nitrate

Figure 1

Study area. (a) Topography with the lowest elevation of 750 m a.s.l. and the highest elevation of 1700 m a.s.l.; (b) aquifer types (the introduction can be found in the text), groundwater and surface water flow direction, and spring sampling sites. The bigger dots indicate the spring samples with higher discharges.