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Accueil du site > Français > Les annonces de séminaires et thèses > Séminaire de Ji-Hyung Park (Université de Kangwon, Corée du Sud)

Séminaire de Ji-Hyung Park (Université de Kangwon, Corée du Sud)

Date : 8 juillet 2011, 11h

Titre : Watershed-level responses of dissolved and particulate organic carbon export to rainfall variability & extremes.

Lieu : Salle de Conférences du CAREN (bât. 14B RDC)

Résumé : Land-water transport of dissolved organic carbon (DOC) and particulate organic carbon (POC) represents a crucial link in the global C cycle. Recent studies have suggested that hydrologic carbon export via soil erosion and leaching can transfer a substantial portion of the annual soil C sequestration to aquatic systems. To provide baseline data essential for predicting changes in hydrologic carbon export from mountainous watersheds in a changing climate, responses of DOC and POC export to rainfall variability and extremes were investigated in a mountainous mixed land-use watershed in northern South Korea, using a combined approach of stream sampling on various time scales, in-stream optical measurements, and stable isotopes. Routine biogeochemical monitoring at a forested subcatchment and a watershed outlet receiving agricultural runoff over two years showed generally higher concentrations of DOC than POC in precipitation, throughfall, forest floor leachates, and both forest and agricultural streams. However, intensive storm sampling and high-frequency in-stream measurements captured larger, nonlinear increases in streamwater POC concentrations exceeding DOC concentrations during peak flow periods of intense storms. Comparison of δ13C, δ15N, 206Pb/207Pb and 208Pb/206Pb among source soils and suspended sediments suggested varying sediment sources during storms, including the forest floor, streambank, and cropland soils. The results suggest that the hydrologic export of soil organic carbon from erosion-prone mountainous watersheds can significantly increase in response to more frequent occurrence of extreme storm events.