Christian Temme

Polychlorinated biphenyls in air and water of the North Atlantic and Arctic Ocean

Air and seawater samples were collected on board the R/V Polarstern during a scientific expedition from Germany to the Arctic Ocean during June–August 2004. The air data show a strong decline with latitude with the highest polychlorinated biphenyl (PCB) concentrations in Europe and the lowest in the Arctic. ΣICES PCBs in air range from 100 pg m−3 near Norway to 0.8 pg m−3 in the Arctic. A comparison with other data from previous and ongoing land-based air measurements in the Arctic region suggests no clear temporal decline of PCBs in the European Arctic since the mid-1990s. Dissolved concentrations of Σ6PCBs (28/31, 52, 101, 118, 138, 153) in surface seawater were <1 pg L−1. Dominant PCBs in seawater were 28/31 and 52 (0.1–0.44 pg L−1), with PCBs 101, 118, and 138 < 0.1 pg L−1. In seawater, PCB 52 displayed the highest concentrations in the northernmost samples, while PCBs 101, 118, and 138 showed slightly decreasing trends with increasing latitude. Fractionation was observed for PCBs in seawater with the relative abundance of PCBs 28 and 52 increasing and that of the heavier congeners decreasing with latitude. However, in air only 15–20% of the variability of atmospheric PCBs can be explained by temperature. Owing to large uncertainties in the Henrys Law constant (HLC) values, fugacity quotients for PCBs were estimated using different HLCs reported in the literature. These indicate that on average, deposition dominates over volatilization for PCBs in the Arctic region with a strong increase in the middle of the transect near the marginal ice zone (78–79°N). The increase in fugacity ratio is mainly caused by an increase in air concentration in this region (possibly indirectly caused by ice melting being a source of PCBs to the atmosphere).

Measurements of atmospheric mercury species at a German rural background site from 2009 to 2011 – methods and results

Environmental context Mercury is a very hazardous substance for human and environmental health. Systematic long-term direct measurements in the atmosphere can provide valuable information about the effect of emission controls on the global budget of atmospheric mercury, and offer insight into source–receptor transboundary transport of mercury. A complete setup for the measurement of the four most relevant atmospheric mercury species (total gaseous mercury, gaseous oxidised mercury, particle-bound mercury, and gaseous elemental mercury) has been operating at the rural background site of Waldhof, Germany, since 2009. We present the dataset for 2009–2011, the first full-speciation time series for atmospheric mercury reported in Central Europe. Abstract Measurements of mercury species started in 2009 at the air pollution monitoring site ‘Waldhof’ of the German Federal Environmental Agency. Waldhof (52°48′N, 10°45′E) is a rural background site located in the northern German lowlands in a flat terrain, 100km south-east of Hamburg. The temporally highly resolved measurements of total gaseous mercury (TGM), gaseous oxidised mercury (GOM), particle-bound mercury (PBMPM2.5, with particulate matter of a diameter of ≤2.5µm) and gaseous elemental mercury (GEM) cover the period from 2009 to 2011. The complete measurement procedure turned out to be well applicable to detect GOM and PBMPM2.5 levels in the range of 0.4 to 65pgm–3. As the linearity of the analyser was proven to be constant over orders of magnitude, even larger concentrations can be measured accurately. The 3-year median concentration of GEM is found to be 1.61ngm–3, representing typical northern hemispheric background concentrations. With 6.3pgm–3, the 3-year average concentration of PBMPM2.5 is found to be approximately six times higher than the 3-year average GOM concentration. During winter the PBMPM2.5 concentration is on average twice as high as the PBMPM2.5 summer concentration, whereas the GOM concentration shows no clear seasonality. However, on a comparatively low level, a significant diurnal cycle is shown for GOM concentrations. This cycle is most likely related to photochemical oxidation mechanisms. Comparison with selected North American long-term mercury speciation datasets shows that the Waldhof 3-year median speciated mercury data represent typical rural background values.