The field work will concentrate on 4 characteristic study sites (Rhine River, Rhine estuary, coastal North Sea and Skagerrak). Additionally, a high latitude 
coastal Arctic station will be sampled. We will characterize the DOM pool and its molecular weight fractions and determine the trace metal concentration (Fe, 
Cu, Cd, Mn) and speciation in the different DOM molecular weight fractions. In situ and lab experiments will be performed to determine the alterations in the 
DOM-metal complex upon exposure to UV radiation. In these experiments, the formation of photoproducts from the DOM will be followed as well as the changes in 
metal speciation. In bio-assay experiments, the UV-induced changes in the bioavailability of selected metal species will be investigated. Biological weighting 
functions for the response of microbial community to the exposure to UV radiation and its subsequent recovery are determined. Micro- and mesocosm experiments 
at selected sites will be performed to investigate the complex interaction between the DOM-metal complex and the microplankton component of the food web in 
the presence of UV radiation. All the data acquired are directly entered in an existing model, which will be expanded significantly to allow predictions on 
the future development of the physico-chemical interactions in the DOM-metal complex model and its interaction with the planktonic component of the food 
web in European waters. 
            

Water column profiles of the underwater radiation regimens including the ultraviolet radiation (UVR) were made in October/November 2000 in the coastal North 
Sea, the estuary of the River Rhine and the River Rhine. Attenuation coefficients have been calculated from these data and formed the input required for WPs 
3 to 5. These data are now used for the modelling component as well (WP6). Following the intensive sampling campaign outlined in the 3rd Management Report in 
the Rhine river estuary (Lek, Waal, Schelde) and the coastal North Sea analysis were performed on the collected samples. Water samples were taken for dissolved 
organic carbon (DOC), absorbance, and fluorescence measurements as well as for ultrafiltration. According to WP 2 the following detailed analysis were conducted 
on the high molecular weight fractions of Rhine river, estuarine, and North Sea samples during summer and fall 2001. We have completed measurements of BWFs, 
on three phytoplankton species in culture, using three different parameters (14Carbon fixation, photosynthetic electron transport [PAM] and growth). 
Each measurement is performed on a spectral radiation resolution of 1 nm. We are now doing the modelling part using the technique developed by Cullen et al using 
PCA. We will however compare this technique with the more traditional technique described by Rundel.    
   
To elucidate the influence of UVB on the bioavailability of metal and DOC mesocosm/microcosm experiments were made with 3 different water types: arctic 
water (Ny-Ålesund/Svalbard), temperate waters strongly influenced by terrestrial matter (Isefjord/Denmark) and surface water from Øresund/Denmark 
only weakly influence by terrestical matter. The bioavailability of metals was measured by means of Diffusive Thinlayer Gradients (DGT), a new sensitive 
methods for time-integrated monitoring and very easy to handle. UVB effect on DOM was only seen in the Isefjord water. In the two others water types no effects 
of UVB were seen on the DOC, neither in concentration nor in absorbance at 250 and 365 nm. UVB has no effect on the bioavailability of the metals in any of the water 
types, however the DOM concentration and quality in the water tested was very different. Comparison between the arctic water and Isefjord water indicates 
3-4 times lower concentration of the bioavailable Fe, Mn and As in the arctic water. Opposite, the concentration of bioavailable Cd, Cu, Cr and Zn was 3-10 times 
higher in the arctic water. Bioavailable concentrations of Al, Co, Ni and Pb were almost similar in the two water types. The result is important since the impact 
of metals on biota does not depend primarily on their total concentrations but on the concentration of the bioavailable form(s). Moreover, single species 
experiments were performed at the Univ. Göteborg using phytoplankton cultures in the laboratory. One aim was to measure combination effects of copper and 
UVBR for inhibiting photosynthesis and growth of a diatom (Phaeodactylum tricornutum). The ERSEM (European Regional Sea Ecosystem Model) has been used to 
incorporate a module for the UVR-DOM-metal interactions and their role in pelagic food webs. To the ERSEM the Princeton Ocean model has been added and parameters 
which should enter the model have been determined 
            

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