Modelling the cycling and fate of persistent organic pollutants (POPs) in the North Sea and coastal and shelf systems: past and future

Kieran O'Driscoll

Research output: Contribution to conferenceOtherpeer-review


The cycling and fate of two selected legacy persistent organic pollutants (POPs), PCB 153 and γ-HCH, have been investigated for the North Sea system using combined hydrodynamic (HAMSOM, Hamburg shelf ocean model) and fate and transport ocean models (FANTOM). FANTOM processes include air-sea exchange, river input, partitioning between water and POC (particulate organic carbon), sinking and resuspension, degradation in water and sediment, diffusion, advection, and exchange with adjacent water bodies. Results of simulations are presented and discussed.

Contemporary simulations were made for the 10-year period 1996–2005. Model output was validated by comparing results with available data, which showed the simulations to be of very satisfactory quality. Results show that the North Sea is a net sink for γ-HCH and a net source to the atmosphere of PCB 153. Total masses of γ-HCH and PCB 153 in 2005 are reduced to 30% and 50%, respectively, of 1996 values. Storms resuspending bottom sediments into the water column mobilise POPs into the atmosphere and have the potential to deliver substantial loads of these POPs into Europe.

To investigate the impact of climate variability on POPs in the North Sea in the 21st century, future scenario model runs for three 10-year periods to the year 2100 using plausible levels of both in-situ concentrations and atmospheric, river and open boundary inputs were performed. Dry gas deposition and
volatilization of γ-HCH increase in the future relative to the present by up to 20% (in the spring and summer months for deposition and in summer for volatilization). In the water column, total mass of γ-HCH and PCB 153 remain fairly steady in all three runs. In sediment, γ-HCH increases in the future runs, relative to the present, while PCB 153 in sediment decreases exponentially in all
three runs, but even faster in the future, due to the increased number of storms, increased duration of gale wind conditions and increased water and air temperatures, all of which are the result of climate change.

Finally, a model for investigating the fate and cycling of POPs in marine ecosystems, including the uptake and exchange of POPs at lower trophic levels (phytoplankton and zooplankton), is introduced. The state-of-the-art ‘ecosystem approach’ to POP modelling will be developed in consultation with
national and European policy makers within the EU Marine Strategy Framework Directive.
Original languageEnglish
Publication statusPublished - 13 Apr 2016
Event10th Network Conference on Persistent Organic Pollutants - Birmingham, United Kingdom
Duration: 13 Apr 201614 Apr 2016


Conference10th Network Conference on Persistent Organic Pollutants
Country/TerritoryUnited Kingdom
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