Brown T.N. 1 , Wania F. 1 , Breivik K. 2 , Goss K.U. 3

1. 3 2 1 0 No Deviation Mostly in Air Mostly in Sediment or Soil* AW -1 Significant Deviation K log -2 -3 -4 -5 -6 3 4 5 6 7 8 9 10 11 12 13 log K Mostly in Water or Soil* OA Mostly in Water Minor Deviation 3 3 2 2 *Environmental fate depends on the emission scenario. 1 1 CoZMo-POP2 MMTF Model 0 0 -1 -1 AW AW K K -2 -2 log log -3 -3 -4 -4 -5 -5 -6 -6 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 log log K K OA OA Wania F., Breivik K., Persson N.J., McLachlan M.S. Environmental Modelling Software, 2006, 21, 868-884. Summary TESTING A DYNAMIC MULTI-MEDIA MODEL DESCRIBING ENVIRONMENTAL PHASE PARTITIONING WITH POLY-PARAMETER LINEAR FREE ENERGY RELATIONSHIPS • a multimedia transport and fate model is modified to better describe partioning for polar chemicals • partioning to organic matter is described with poly-parameter linear free energy relationships instead of assuming a linear relationship with partitioning to octanol • the degree of affinity for organic matter is found to be the most important factor affecting the results • it is found that using octanol as a surrogate for organic carbon fails to capture all of the molecular interactions of organic carbon, not only for polar chemicals but for relatively non-polar chemicals too in some cases Brown T.N.1, Wania F.1, Breivik K.2, Goss K.U.3 1 Department of Chemistry and Department of Physical and Environmental Sciences, University of Toronto Scarborough, Canada. 2 University of Oslo, Department of Chemistry, Norway. 3 Helmholtz Zentrum für Umweltforschung UFZ, Department Analytik, Germany Introduction Results & Discussion Environmental partitioning of chemicals after 10 years of static emissions, using spLFERs to describe partitioning • Commonly applied single parameter linear free energy relationships (spLFER) assume that molecular interactions with organic carbon (OC) can be approximated by the interactions with octanol • a poly-parameter linear free energy relationship (ppLFER) describes interactions between any two phases as the sum of specific (hydrogen bonding) and non-specific (dipole, van der Waals) interactions • replacing spLFERs with ppLFERs in multi-media transport and fate (MMTF) models is expected to increase their domain of applicability to polar molecules Deviation from results of spLFER calculations when using ppLFERs instead Methods • the octanol-based spLFERs for atmospheric particles and POC in soil, water and sediment compartments were replaced with ppLFERs in CoZMo-POP2 • chemicals can be divided into groups based on their partitioning behaviour • emissions to air, soil and water were tested; mode of emission was only found to be significant for some chemicals • each pair of chemicals in figure above is predicted to have very similar environmental fates based on calculations using the octanol spLFER • calculations were repeated for the chemicals using ppLFERs to describe partitioning instead of spLFERs • the degree of difference between the results was found to be largely unrelated to the environmental fate of the chemicals • the primary factor affecting the results is the affinity of the molecules for organic matter, with increasing affinity leading to increased deviations When using ppLFERs instead of spLFERs, in some emission scenarios not only did chemical behaviour deviate from spLFER calculations, but the behaviour of each pair of chemicals was found to be divergent as well • Diphenylmethanone (DPM) and 3,4-dichlorophenol (3,4-DCP) behave very similarly using both LFERs if they are emitted to water; they both remain in the water • emissions to air or soils results in different ratios partitioned to soil and water • spLFER calculations predict that a larger fraction of 3,4-DCP will be sorbed to soils than DPM • ppLFER calculations predict the opposite outcome; 3,4-DCP is predicted to be much more efficiently washed out of soils by runoff due to its increased hydrogen bond donor capacity • solute descriptors, which describe the molecular interactions of specific chemicals, were obtained for 932 chemicals in the model’s domain of applicability • 20 chemicals were selected for more detailed analysis based on initial results diphenylmethanone (CAS 119-61-9) 3,4-dichlorophenol (CAS 95-77-2) • PCB-155 and PCN-46 behave very similarly using both spLFER and ppLFER data if they are emitted to soil, they both remain in the soil • emission to air causes slightly more PCN-46 than PCB-155 to be partitioned to soil • emission to water increases this effect; dramatically more PCN-46 than PCB-155 is partitioned to the soil • the reasons for this are complex, but is most likely related to the full ortho-substitution of PCB-155 which appears to increase its affinity for water PCN-46 (CAS 3432-57-3) PCB-155 (CAS 33979-03-2) Conclusion • if chemicals partition only weakly to organic phases then using spLFERs is acceptable for describing their environmental behaviour • chemicals that sorb more strongly to organic phases the potential error cause by assuming that octanol is a good surrogate for organic matter increases • divergent behaviour of chemicals when using ppLFERs demonstrates that partioning into octanol fails to capture all of the proper interactions, even for chemicals believed to be well described by this spLFER • Ibuprofen and Octhilinone behave very similarly using both spLFER and ppLFER data if they are emitted to water; they both remain in the water • Ibuprofen and Octhilinone have both hydrogen bond donator and acceptor character, but Ibuprofen has more of each, this causes ibuprofen to have elevated levels in water when emissions are to air or soil Acknowledgements We acknowledge funding from the Long-range Research Initiative of the European Chemical Industry Association (CEFIC). Ibuprofen (CAS 15687-27-1) Octhilinone (CAS 26530-20-1)