The water sampling frequency of the joint operation with the Stockholm Water monitoring program is at least one times per month at 12 levels with a depth of: 5, 15, 30, 50, 60, 70, 80, 85, 90, 95, 100m. Parameters that will be analyzed are: PO4, Ptot, NO3, NO2, NH4, Ntot, Dsi, SO4, H2S. The methods used include spectrophotometric methods, auto-analysis and micro-electrode measurements of sulphur.
Conductivity, Temperature, Depth (CTD) Sensors are used at various depth for continuous measurements of these parameters.
Sediment sampling, analysis and evaluation
Sediments are characterized in terms of water content and organic content in different layers. Sediment dating to estimate sediment growth will be performed using radiocesium isotopes as a tracer. Phosphorus fractionation will be used to quantify the mobile pool of phosphorus in the sediments and how this may change during the project. The sediments will also be analyzed for their content of iron, manganese and cadmium. The survey will quantify any changes in the storages of phosphorous and selected metals within the sediment compartment. Moreover, sediment traps are installed to monitor the concentrations of phosphorus in settling matter.
Monitoring of macrobenthic fauna will be undertaken before, during and after oxygenation in the Kanholmsfjärden site. Starting from the deepest hypoxic zone sampling will move upwards until animals are found. At the deepest point where macrozoobenthos are found, a triplicate will be collected. Each sample is analysed for biomass, abundance and taxa/species distribution. To investigate if oxidation of sediments can lead to ecotoxicological effects at different trophic levels sediments from Kanholmsfjärden are oxidized in the laboratory and tests are performed using three organisms (Macoma, Marenzelleria and Mysis). The organisms will be exposed to the reduced sediments and water that successively increase its oxygen content.
In Hanöbukten, local partners perform exploratory fishing before, during and after oxygenation to study if the experiment affects the fish population, including attraction of fish to the pumping device.
With the contribution of the LIFE financial instrument of the European Community