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Biological, physico-chemical and biogeochemical dynamics of hydrophobic organ compounds
Stockholm University, Faculty of Science, Department of Zoology.
1997 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents new findings pertaining to several processes that govern the fate and effects of hydrophobic organic compounds (HOCs) in the environment. Two groups of HOCs, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), have been used as model compounds.

Equilibrium partitioning between particles and water studied in the field, reveals that for PCBs and for PAHs, the sorption is significantly stronger than has previously been assumed on the basis of laboratory studies. The partitioning of HOCs between dissolved organic carbon (DOC) and water was also studied. The results showed that under most conditions this matrix had considerably less sorbing capacity than particulate organic carbon, and that the sorption mechanism differs from the particle-water partitioning.

The work carried out in this thesis also showed that during periods of phytoplankton growth, partition coefficients, and thus concentrations of HOCs, in the field are lower for phytoplankton than for free-living pelagic bacteria. This is due to the fact that the sorption kinetics in the larger phytoplankton is slower than growth rate. The free-living pelagic bacteria have been shown to be an important input route for organic carbon to the pelagic foodweb, on an annual basis comparable to grazing of phytoplankton. These results therefore imply that free-living bacteria may be a more important input route of HOCs to the pelagic foodweb than phytoplankton.

Large scale fate processes of PCBs and PAHs were studied in the Baltic Sea. A budget was compiled and revealed important differences in the environmental behaviour between PCBs and PAHs. PCBs seem to be intensively recycled over the air-water, and sediment-water interfaces, while PAHs to a greater extent appear to follow a one-way fate with atmospheric deposition, sedimentation and subsequent burial in the sediments. Since PAHs are released in connection to combustion processes they may reach the environment strongly associated to soot particles, which in turn prevent exchange with the surrounding media. PCBs, on the other hand, reach the environment mainly via diffusive processes by the release of single molecules which then participate in dynamic partitioning.

Finally, although several studies including this thesis, show that the concentrations in waters close to populated areas have decreased significantly since PCBs were banned, budget calculations for PCBs in the Northern Hemisphere indicates that these pollutants are only very slowly removed from the remote areas of the global environment.

Place, publisher, year, edition, pages
Stockholm: Stockholms universitet , 1997. , 42 p.
National Category
Biological Sciences
Research subject
Animal Ecology
URN: urn:nbn:se:su:diva-47760ISBN: 91-87272-52-0OAI: diva2:374112
Public defence
1997-05-23, Magnélisalen, Svante Arrhenius väg 12, Stockholm, 14:00 (English)
Härtill sju uppsatser.Available from: 2010-12-02 Created: 2010-12-02 Last updated: 2010-12-02Bibliographically approved

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