WasserCluster Lunz – Interuniversitäre Forschungseinrichtung www.wcl.ac.at Master thesis „Efficiency of self-purification in streams along a gradient of pollution” Background and aim: Natural headwaters possess a high potential for in-stream nutrient and organic matter uptake. Increasing pollution through nutrient loadings from agriculture and channelization may impact this self-purification capacity, thereby degrading headwaters to mere transport systems. The aim of the project PowerStreams is to determine the efficiency of the nitrogen and carbon uptake in differently impacted streams via in-field short-term nutrient addition experiments. Tasks: Conduct in-field short-term nutrient addition experiments with nitrate, ammonium, and acetate in differently impacted streams; Analyze water and sediment chemistry (amongst others, C and N concentrations in water and sediments, activity of extracellular enzymes, microbial abundances, …); calculate nutrient and organic carbon uptake; statistical analyses of the efficiency of self-purification. Location: WasserCluster Lunz, Lunz/See Start: February 2015 Contact: Dr. Gabriele Weigelhofer [email protected] Dr. Thomas Hein [email protected] AG Bioframes -Biogeochemical Functions: Research And Management in Ecosystems at multiple Scales WasserCluster Lunz – Interuniversitäre Forschungseinrichtung www.wcl.ac.at Master thesis „The self-purification capacity of streams: Effects of long-term organic pollution on the in-stream uptake of nitrate and ammonium“ Background and aim: Natural headwaters possess a high potential for in-stream nutrient and organic matter uptake. Nutrients may be retained and removed from the water column via abiotic and biotic processes. These processes are influenced by the interaction between benthic algae and microorganisms and may be changed by long-term organic pollution. The aim of the project PowerStreams is to analyze the effects of long-term additions of bioavailable organic carbon on the in-stream uptake of nitrate and ammonium and on the benthic metabolism via long- and short-term addition experiments in experimental stream reaches or flumes. Tasks: Conduct in-field long- and short-term nutrient addition experiments with nitrate, ammonium, and acetate in experimental stream reaches or flumes; Analyze water and sediment chemistry (amongst others, C and N concentrations in water and sediments, activity of extracellular enzymes, microbial abundances, …); calculate nutrient and organic carbon uptake; statistical analyses of the efficiency of self-purification. Location: WasserCluster Lunz, Lunz/See Start: earliest summer 2015; latest spring 2016 Contact: Dr. Gabriele Weigelhofer [email protected] Dr. Thomas Hein [email protected] AG Bioframes -Biogeochemical Functions: Research And Management in Ecosystems at multiple Scales