Modelling of POP Hemispheric Transport

MSC-E Technical Report 8/2002

A.Malanichev, V.Shatalov, N.Vulykh, B.Strukov

ABSTRACT

This technical report describes the progress in the investigation of POP long-range transport and accumulation in the Northern Hemisphere. For considered POPs (PAHs, PCDD/Fs, PCB, g-HCH and HCB) investigation of their long-range transport potential was carried out. This demonstrated the necessity of some POP modelling on the hemispheric scale. A pilot version of hemispheric multicompartment POP transport model is under development and preliminary calculations of PCB, g-HCH and HCB are carried out. Besides model description of sea currents and experimental sea ice transport module is under investigation.

On the basis of the above-mentioned activity the following results were obtained:

- Assessment of long-range transport potential made on the basis of the regional MSCE-POP model allowed one to select substances for hemispheric modelling (PCB, g-HCH and HCB).

- Brief review of existing model approaches to POP assessment on the hemispheric scale was carried out. The hemispheric model for evaluation of POP pollution is based on the atmospheric transport module with advection Bott scheme. It operates in the geographical coordinates with spatial resolution 2.5°x2.5° and vertical s-coordinate. Apart from the atmosphere, the model includes special modules describing processes in soil, seawater and vegetation.

- The pilot calculations of PCB, g-HCH and HCB hemispheric transport for 1990 confirmed the operability of the model. They showed that for European region air concentrations are in a reasonable agreement with those obtained by regional model and lay in the range close to monitoring data. Pollutants emitted from the European sources are transported to such remote regions as the Arctic, Asia and North America. The highest ability to long-range transport demonstrates HCB. For more accurate pollution assessment modelling should be made during rather long period (e.g. up to 30 years for PCBs).

- The pilot version of the sea ice module was prepared and tested. Besides a refinement of redistribution of pollutants between different phases and sedimentation in the marine environment was suggested. Numerical experiments showed that this modification improved description of POP behavior in seawater.

- Further development of the hemispheric model is aimed at improvement of process descriptions in the different environmental compartments. For the atmosphere the scavenging with snow will be introduced in the model. For soil a redistribution of POPs between air, soil solute, organic matter and dissolved organic will be refined. More attention will be paid to degradation processes in the atmosphere, soil and seawater. Seawater module will be complemented with more detailed description of sedimentation and partitioning processes. Besides sea ice POP transport module will be improved and integrated into the hemispheric model.

Some supplementing information on POP behavior in the environment is presented here.