HR: 0800h
AN: H51D-1174    [Abstracts]
TI: Hydrochemical Modeling of Dissolved Organic Carbon in a Small, Undisturbed, Forested Watershed in Southern Chile
AU: * Valdivia, M V
EM: mvv2@cornell.edu
AF: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AU: Walter, M T
EM: mtw5@cornell.edu
AF: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AU: Salmon, C D
EM: cds8@cornell.edu
AF: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AU: Hedin, L O
EM: lhedin@princeton.edu
AF: Department of Ecology and Evolutionary Biology and Princeton Environmental Institute, Princeton University, Princeton, NJ 08544 United States
AU: Walter, M F
EM: mfw2@cornell.edu
AF: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AB: The objective of the present study is to model Dissolved Organic Carbon (DOC) concentrations in a stream draining a small, undisturbed, old-growth forested watershed in Southern Chile and test model results against measured data. DOC plays an important role in several processes in terrestrial and aquatic ecosystems. For example, through the formation of organic complexes, DOC can influence nutrient availability, affect the solubility, mobility, and toxicity of metals, and control the absorption of pesticides to soils. DOC also influences biological activity by absorbing UV-B radiation and can contribute significantly to freshwater acidity. Additionally, DOC is linked to the formation of trihalomethanes as by-products of the disinfection of drinking water with chlorine, which constitutes a potentially serious threat to human health. Despite plentiful research on biogeochemical processes controlling DOC production and consumption, there is little information from minimally impacted environments, which can provide valuable baseline information from which to evaluate the more impacted ecosystems. Our study focused on a virtually unpolluted old-growth forested watershed in Southern Chile. We developed a conceptual model that assumes DOC production in forest soils is a function of temperature and DOC transport from soil to stream water is a function of discharge and hydrological flow paths. The hydrological response of the catchment under study was simulated using a simple lumped model, based on two years of meteorological data previously collected. Three different equations were used to simulate DOC concentrations in soil water as a function of temperature, and ultimately to derive DOC concentrations in streamflow. Model results were tested against two years of measured DOC concentrations in streamflow, and all three models provided a reasonably good representation of the DOC response of the small studied watershed and a better agreement to the observed DOC than previously published, similarly simple models.
DE: 1806 Chemistry of fresh water
DE: 1831 Groundwater quality
DE: 1860 Runoff and streamflow
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting