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Retention of Sediments and Nutrients in the Iron Gate I Reservoir on the Danube River

Teodoru, Cristian ; Wehrli, Bernhard

In: Biogeochemistry, 2005, vol. 76, no. 3, p. 539-565

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    Titre
    • Retention of Sediments and Nutrients in the Iron Gate I Reservoir on the Danube River
    Auteur
    • Teodoru, Cristian. Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology (ETH), Limnological Research Center, Seestrasse 79, CH-6047, Kastanienbaum, Switzerland
    • Wehrli, Bernhard. Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology (ETH), Limnological Research Center, Seestrasse 79, CH-6047, Kastanienbaum, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Biogeochemistry, 2005, vol. 76, no. 3, p. 539-565. Kluwer Academic Publishers
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:317143
    Summary
    This work addresses an intensively debated question in biogeochemical research: "Are large dams affecting global nutrient cycles?” It has been postulated that the largest impoundments on the Lower Danube River, the Iron Gates Reservoirs, act as a major sink for silica (Si) in the form of settling diatoms, for phosphorus (P) and to a lesser extent for nitrogen (N). This retention of P and N in the reservoir would represent a positive contribution to the nutrient reduction in the Danube River. Based on a 9-month monitoring scheme in 2001, we quantified the nutrient and the sediment retention capacity of the Iron Gate I Reservoir. The sediment accumulation corresponded to 5% TN (total nitrogen), 12% TP (total phosphorus) and 55% TSS (total suspended solids) of the incoming loading. A mass balance revealed that more N and P are leaving the reservoir than entering via the inflow. Based on these current results, the reservoir was temporarily acting as a small nutrient source. The nutrient accumulation in the sediments of the Iron Gate I Reservoir represents only 1% of the "missing” load of 106t N and 1.3 × 105t P defined as the difference between the estimated nutrient export from the Danube Basin and the measured flux entering the Black Sea. This result disproves the hypothesis that the largest impoundment on the Danube River, the Iron Gates Reservoir, plays a major role in N and P elimination