Identification of nitrate sources in groundwater using a stable isotope and 3DEEM in a landfill in Northeast China

Abstract The groundwater was sampled in a typical landfill area of the Northeast China. Coupled stable isotope and three dimensional excitation–emission matrix (3DEEM) were applied to dentify diffused NO 3 − inputs in the groundwater in this area. The results indicated that combined with the feature of groundwater hydrochemistry and three-dimensional fluorescence technology can effectively identify the nitrate pollution sources. The nitrate was derived from manure and sewage by δ 15 N and δ 18 O–NO 3 − values of groundwater in the different periods. The excitation–emission matrix fluorescence spectroscopy was further evidence of groundwater DOM mainly which comes from the landfill. The protein-like was very significant at the sampling points near the landfill (SPNL), but only fulvic acid-like appeared at downstream of the landfill groundwater sampling points (DLGSP) in the study area. Partial denitrification processes helped to attenuate nitrate concentration in anaerobic environment.