Variables: dissolved_oygen dissolved_organic_carbon electric_conductivity Substances: 18-beta-Glycyrrhetinic acid (MPDGHEJMBKOTSU-YKLVYJNSSA-N) 2 -2 -Difluorodeoxyuridin (FIRDBEQIJQERSE-QPPQHZFASA-N) Systems: groundwater Keywords: monitoring high resolution mass spectrometry land use