Detecting transboundary environmental pressures and consequences
The environmental pressures faced by the North Sea system are oblivious to national boundaries. Impacts from over-fishing and transport of contaminants provide good examples of pressures with transboundary causes and consequences. In order to mount effective monitoring and assessment there is a need to move beyond the nationally focussed monitoring toward integrated and coherent multinational initiatives.
SmartBuoy measurements in the North Sea provide high frequency fixed point observations of a range of physical, chemical and biological variables. They are providing long-term observations critical to the assessment of eutrophication as currently required by OSPAR and various EU Directives. They also provide measurements that can be combined with similar data from other sources such as spatial data from FerryBox to give greater confidence in environmental assessments. A comparison between SmartBuoy and FerryBox observations was carried by Wehde et al together with an application of a hydrodynamic model. Without the application of the hydrodynamic model the comparison between the observations show a poor relationship. However, when water masses measured with the FerryBox were introduced as Lagrangian Tracers in to a General Circulation Model (GCM) their spatial displacement was pFebruary 28, 2006d in a much improved agreement between buoy and FerryBox data. This counts for quasi conservative parameters like salinity. For non conservative parameters like chlorophyll the results still remain unsatisfactory. Therefore, a biological module was implemented to estimate the changes in phytoplankton chlorophyll concentration within the time span the water mass is transported from the SmartBuoy to the ferry route. This results in much improved agreement between the two data sets. This study illustrates one method for simulation and quantification of the transport of contaminants contained within water masses.
Chlorophyll fluorescence observed at Cefas Gabbard buoy (upper panel) and chlorophyll fluorescence of water passively transported within the GCM (lower panel)
Comparison between observed FerryBox Chl Fluorescence (lower panel) and estimated chlorophyll for tracers starting from the Gabbard and drifting to the FerryBox route (upper panel)
Questions concerning the extent of transboundary transport of nutrients have arisen as a result of European member states citing the cause of eutrophication in their own maritime waters as due to anthropogenic nutrient enrichment sourced from another state. The answers to such questions require the combined use of data and models to provide estimates of fluxes. Collaborative efforts between member states to gather and provide data as well as agreement on choice and method for application of appropriate models are more likely to lead to more widely acceptable answers.
