Ammonium ion Carbon Carbon cycle Cenozoic Critical load Detection Drainage basins East Asian Summer Monsoon El Nino Factor analysis Fluvial environment Geochemical cycle Geochemistry Grasslands Holocene Jingcun China Jinghe River Land cover Land use Monsoons Nitrate ion Nonpoint sources Northeastern China Paleoclimatology Paleoecology Paleoenvironment Paleosols Pollutants Pollution Principal components analysis