Assessing the seasonality of the distribution of persistent organic pollutants (POPs) in water and plankton of a subalpine lake.

POPs have become a major concern because of their diffusion, toxicity, persistence and ability to bioaccumulate. Once they enter the water ecosystem, POPs generally persist long time and their fate is largely controlled by the partitioning with suspended or dissolved organic carbon. Internal fluxes of C and energy determines to which extent POPs will be deposited to sediment or be addressed to the trophic web. The budget of organic carbon in water is the results of a complex interaction between parameters such as nutrients availability, environmental conditions, genes control, etc. This can generate very dynamic scenarios. For example algal blooms are conditions in which the amount of particulate organic matter can change considerably in a shorter amount of time. So far, POP fate has been addressed in such dynamic scenarios only through modelling. The present proposal is linked to an ongoing research project aimed to assess the fate of selected POPs (namely PCBs and organochlorine pesticides) in a strongl y dynamic ecological scenario (a spring algal bloom in a subalpine mesotrophic lake). Such project, leaded by a NIVA researcher is the result of a collaboration with the Lancaster Environment Centre. Within the project, sampling and chemical analysis of w ater dissolved phase and particle fraction has been already carried out during the last year. The period of 2 months requested here by the applicant will allow her collaborating closely with the Norwegian researcher for the phase of data analysis, interpr etation and manuscript writing. The results from this project will provide information for the parameterization of dynamic models of the fate of POPs in the water system and will be useful for obtaining insights on the coupling between biogeochemical driv ers and the exposure of the pelagic food web to POPs.