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The export of dissolved and particulate organic carbon and nitrogen in two forested catchments during heavy precipitation events in South Korea

Mi-Hee Lee1, Jean-Lionel Payeur-Poirier2, Silvia Parra3, Ji-Hyung Park4, Bomchul Kim5, Gerhard Gebauer3, Stefan Peiffer2, Egbert Matzner1
1 Department of Soil Ecology, University of Bayreuth, BayCEER, Germany
2 Department of Hydrology, University of Bayreuth, Germany
3 BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Germany
4 Department of Environmental Science and Engineering, Ewha Womans University, Republic of Korea
5 Department of Environmental Science, Kangwon National University, Republic of Korea

P 7.14 in Controls of dissolved organic matter fluxes in ecosystems

Poster Session 1 on Monday, 16:30-18:30

The export of organic carbon (C) and nitrogen (N) from terrestrial to aquatic systems can occur in the form of dissolved organic C and N (DOC, DON) but also in the form of particulate organic C and N (POC, PON). Heavy precipitation events induced by monsoon climate can change fluxes and concentrations of dissolved and particulate organic matter (DOM, POM) in runoff by surficial soil erosion and variable water flow paths. Tree species might affect the export of organic C and N from forested catchments to runoff by different litter and humus quality in forest floor.

In this study, we investigated the effect of tree species and of precipitation intensity on the export of fine particulate (0.7µm – 1 mm) and dissolved organic C and N from soils to the runoff in two forested catchments in South Korea. We tested the following hypotheses, 1) During monsoonal precipitation events, export of DOM and POM from mixed forested catchment differs from that of a purely deciduous catchment. 2) The quality and quantity of DOM and POM in throughfall, forest floor percolate and runoff reflects the forest type. 3) Fine PON is the dominant form of N export in runoff, and 4) The concentration response to discharge is similar for C and N.

We collected bulk precipitation, throughfall, forest floor percolate, soil solution, runoff, and hydrological data (precipitation and runoff discharge) in the monsoon season 2013. Water samples were analyzed for DOC, DON, POC and PON, specific ultraviolet absorbance (SUVA), humification index (HIX) and fluorescence spectra.

At runoff events of > 2 mm h-1, POC export was ten times larger than DOC in both forested catchments. The export of DOC, POC, and PON in the purely deciduous catchment was larger than in coniferous/deciduous mixed forested catchment, but no difference was visible in the export of DON. The dominant forms of N export in runoff were PON, NO3-N and DON. For both catchments, the POC/PON ratio in runoff showed almost constant in response to discharge.

Heavy precipitation events trigger high losses of C and N from forested catchments. The export of DOC with runoff during monsoon season is less in mixed forests than in deciduous forests.

Key words: DON, DOC, fine POC, PON, heavy precipitation, runoff, coniferous, deciduous, forested catchment.

Letzte Änderung 19.06.2014