Publication

Summary

There has been an increasing focus on the effects of climate change on dynamics and mobilization of dissolved organic matter (DOM) during the last years. This is partly due to the observed increases in colour and dissolved organic carbon (DOC) concentrations in lakes and rivers (Freeman et al. 2001;Hongve et al. 2004). The knowledge of climatic controls on DOC dynamics is limited, and is even more scarce on dissolved organic matter (DON) dynamics. There are also indications of different responses in DOC and DON dynamics to climatic factors (Kalbitz et al. 2000). Including DON in studies of DOM dynamics is therefore of great importance. The objective of the presentation is to examine the effects of changes in climatic factors on DON mobilization, and to investigate possible differences in release mechanisms for DOC and DON. The work is part of the CLUE (Climate change and Land Use Effects) project (http://www.umb.no/ipm/forskning/clue/), where headwater catchments are manipulated. The manipulations are meant to simulate climatic changes that are predicted for Norway. Three types of manipulations are conducted: 1) Addition of artificial precipitation in summer and autumn, to simulate increased precipitation. 2) Snow removal during winter, to simulate the effects of increased winter temperatures. 3) Isolation during winter, to simulate the traditional thick snowpack, for comparison with treatment 2). DON runoff from treated catchments is compared with DON runoff from reference catchments. In addition DOC:DON ratios in runoff from treated and reference catchments is compared. References Freeman, C., Evans, C. D., Monteith, D. T., Reynolds, B. and Fenner, N. (2001) Export of organic carbon from peat soils. Nature 412, 785. Hongve, D., Riise, G. and Kristiansen, J. F. (2004) Increased colour and organic acid concentrations in Norwegian forest lakes and drinking water - a result of increased precipitation? Aquatic Sciences 66, 231-238. Kalbitz, K., Solinger, S., Park, J. H., Michalzik, B. and Matzner, E. (2000) Controls on the dynamics of dissolved organic matter in soils: A review. Soil Science 165, 277-304.