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MP7 Global Fate of POPs
(142) Does adsorption to black carbon dominate the partitioning of persistent organic pollutants?
Lohmann, R1, 2, 3, Eisenreich, S2, Jones, K1, MacFarlane, J3, Gschwend, P3, 1 Lancaster University, Lancaster, UK2 Rutgers University, New Brunswick, NJ, USA3 MIT, Cambridge, MA, USA
ABSTRACT- The distribution of organic contaminants between dissolved/gaseous and particulate phases was determined in ambient samples from the New Jersey region and sediment suspensions from Boston and New York Harbor. Measured distribution coefficients of ambient PCDD/Fs exceeded predictions based on absorption into the organic carbon (OC) fraction in aerosols by to 1 order of magnitude. In the sediments, observed solid-water distributions exceeded predictions based on focKoc products by 1-2 orders of magnitude for PAHs, PCBs and PCDDs. It is suggested that adsorption to black carbon (BC) dominated the sorption processes in atmosphere and sediments. A combined OC-absorption and BC-adsorption model was used to explain the observed data. The gas-particle partitioning of PCDD/Fs was calculated as Kp = fom Koa / (1012 oct) + fBCKBC-air / (1012 BC) and improved predictions to within a factor of 2 (0.3 log units) of the measured values. In the sediments, the overall partitioning was parameterized including a non-linear BC-adsorption model: Kd = focKoc + fBCKBCCwn-1, with n set to 0.7 and dissolved concentration Cw in g/L. Adsorption to BC emerged as the dominating matrix during atmospheric transport, and even more so in urban sediments.
Key words: gas-particle partitioning, sediment-water partitioning, black carbon, organic carbon
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