Carbon IsotopesCarbonIsotopesNitrogen IsotopesIsotope LabelingOxygen IsotopesCarbon DioxideMethyl ChlorideAtmosphereGeologic SedimentsFossilsNitrogen FixationChemical FractionationPhotosynthesisEthylene DichloridesPaleontologyMethaneXanthobacterPlant LeavesPinus taedaVolcanic EruptionsPeptococcaceaeCarbon MonoxideCarbon CycleCarbonatesBiomassNanotubes, CarbonCarbon Compounds, InorganicPlant TranspirationEpitestosteroneEcosystemFlaveriaRhamnusHistory, AncientSoilMyrtusHyphomicrobiumNitrogen CompoundsSeawaterBiodegradation, EnvironmentalDoping in SportsWaterNitrogen CycleOceans and SeasNitrogen DioxideGas Chromatography-Mass SpectrometryBlood Urea NitrogenNitrogenZinc IsotopesPoaceaePhosphoenolpyruvate CarboxylasePlant StomataRainFresh WaterSulfur IsotopesTreesRibulose-Bisphosphate CarboxylaseExtinction, BiologicalDeuteriumCarbon Monoxide PoisoningTimeReactive Nitrogen SpeciesClimateIron IsotopesChiropteraAcetatesPlantsBacteriaSulfatesAnaerobiosisNitrogen OxidesGeographyPII Nitrogen Regulatory ProteinsCarbon TetrachlorideStrontium IsotopesCarbon SequestrationAmmoniaDietNitratesSeasonsModels, BiologicalRadioisotope Dilution TechniqueFertilizersCarbon DisulfidePhylogenyMass SpectrometryKineticsCarbon RadioisotopesQuaternary Ammonium CompoundsAmino AcidsOxidation-ReductionBiological EvolutionCulture MediaIndicator Dilution TechniquesHydrogenMolecular Sequence DataCarbon Tetrachloride PoisoningGlutamate-Ammonia LigaseUreaHydrogen-Ion Concentration