TY - JOUR

T1 - Emissions of polychlorinated biphenyls in Switzerland

T2 - a combination of long-term measurements and modeling

AU - Diefenbacher, Pascal S.

AU - Bogdal, Christian

AU - Gerecke, Andreas C.

AU - Glüge, Juliane

AU - Schmid, Peter

AU - Scheringer, Martin

AU - Hungerbühler, Konrad

PY - 2015/2/17

Y1 - 2015/2/17

N2 - Ambient air concentrations of polychlorinated biphenyls (PCBs) in Zurich, Switzerland, are reported for the years 2011-2013. These measurements reveal a distinct seasonal trend with PCB concentrations in air during the summer that were three to five times higher than in the winter. We used a long-term dynamic multimedia model to analyze the seasonal trend and to back-calculate urban emissions of PCBs. In contrast to previous short-term studies that considered time periods of several days to months to extrapolate annual emissions, the use of long-term field data and the corresponding model reduces the uncertainty in these extrapolations. Comparison with measured PCB concentrations in air shows that our model is able to reproduce seasonal trends of the six indicator PCBs (iPCBs). The good agreement of the model results with measurements over a time period of three years provides confidence in model outputs and allows us to estimate the total annual PCB emissions of Zurich (86 μg capita(-1) d(-1)). The resulting summer emissions are nine times higher than emissions during winter. Interestingly, this factor corresponds to the expected increase in PCB volatilization due to the effect of temperature on vapor pressure. This finding implies that PCBs in Zurich are probably released mainly by volatilization from sources that are directly exposed to ambient air temperature (i.e., outdoor sources). The derived emissions are in accordance with previous studies performed at the same location and are also in agreement with an existing emission inventory.

AB - Ambient air concentrations of polychlorinated biphenyls (PCBs) in Zurich, Switzerland, are reported for the years 2011-2013. These measurements reveal a distinct seasonal trend with PCB concentrations in air during the summer that were three to five times higher than in the winter. We used a long-term dynamic multimedia model to analyze the seasonal trend and to back-calculate urban emissions of PCBs. In contrast to previous short-term studies that considered time periods of several days to months to extrapolate annual emissions, the use of long-term field data and the corresponding model reduces the uncertainty in these extrapolations. Comparison with measured PCB concentrations in air shows that our model is able to reproduce seasonal trends of the six indicator PCBs (iPCBs). The good agreement of the model results with measurements over a time period of three years provides confidence in model outputs and allows us to estimate the total annual PCB emissions of Zurich (86 μg capita(-1) d(-1)). The resulting summer emissions are nine times higher than emissions during winter. Interestingly, this factor corresponds to the expected increase in PCB volatilization due to the effect of temperature on vapor pressure. This finding implies that PCBs in Zurich are probably released mainly by volatilization from sources that are directly exposed to ambient air temperature (i.e., outdoor sources). The derived emissions are in accordance with previous studies performed at the same location and are also in agreement with an existing emission inventory.

KW - Chemistry

U2 - 10.1021/es505242d

DO - 10.1021/es505242d

M3 - Journal articles

C2 - 25622721

VL - 49

SP - 2199

EP - 2206

JO - Environmental Science & Technology

JF - Environmental Science & Technology

SN - 0013-936X

IS - 4

ER -