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| Titel |
Prediction of gas/particle partitioning of polybrominated diphenyl ethers (PBDEs) in global air: A theoretical study |
| VerfasserIn |
Y.-F. Li, W.-L. Ma, M. Yang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 4 ; Nr. 15, no. 4 (2015-02-18), S.1669-1681 |
| Datensatznummer |
250119438
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| Publikation (Nr.) |
 copernicus.org/acp-15-1669-2015.pdf |
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| Zusammenfassung |
| Gas/particle (G/P) partitioning of semi-volatile organic compounds (SVOCs)
is an important process that primarily governs their atmospheric fate,
long-range atmospheric transport, and their routes of entering the human body. All
previous studies on this issue are hypothetically based on equilibrium
conditions, the results of which do not predict results from monitoring
studies well in most cases. In this study, a steady-state model instead of an
equilibrium-state model for the investigation of the G/P partitioning
behavior of polybrominated diphenyl ethers (PBDEs) was established, and an
equation for calculating the partition coefficients under steady state (KPS)
of
PBDEs (log KPS = log KPE + logα) was developed in which
an equilibrium term (log KPE = log KOA + logfOM
−11.91 where fOM is organic matter content of the particles) and a non-equilibrium term
(log α, caused by dry and wet depositions of particles), both being
functions of log KOA (octanol–air partition coefficient), are included.
It was found that the equilibrium is a special case of steady state when the
non-equilibrium term equals zero. A criterion to classify the equilibrium and non-equilibrium status of PBDEs was also
established using two threshold values of log KOA, log KOA1, and log KOA2, which divide the
range of log KOA into three domains: equilibrium, non-equilibrium, and maximum partition
domain. Accordingly, two threshold values of temperature t, tTH1 when log KOA = log KOA1 and
tTH2 when log KOA = log KOA2, were identified, which divide the range of temperature also into the same three domains for each PBDE congener.
We predicted the existence of the
maximum partition domain (the values of log KPS reach a maximum constant
of −1.53) that every PBDE congener can reach when
log KOA ≥ log KOA2, or t ≤ tTH2. The novel equation developed in this study
was applied to predict the G/P partition coefficients of PBDEs for our
Chinese persistent organic pollutants (POPs) Soil and Air Monitoring
Program, Phase 2 (China-SAMP-II) program and other monitoring programs worldwide,
including in Asia, Europe, North America, and the Arctic, and the results
matched well with all the monitoring data, except those obtained at e-waste
sites due to the unpredictable PBDE emissions at these sites. This study
provided evidence that the newly developed steady-state-based equation is superior to
the equilibrium-state-based equation that has been used in describing the
G/P partitioning behavior over decades. We suggest that the investigation on
G/P partitioning behavior for PBDEs should be based onsteady-state, not equilibrium
state, and equilibrium is just a special case of steady-state when non-equilibrium factors
can be ignored. We also believe that our new equation provides a useful tool
for environmental scientists in both monitoring and modeling research on G/P
partitioning of PBDEs and can be extended to predict G/P partitioning
behavior for other SVOCs as well. |
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