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2018
A complete rethink is needed on how greenhouse gas emissions are quantified for national reporting
Elsevier
2018
Long-term Arctic air monitoring of per- and polyfluoroalkyl substances (PFASs) is essential in assessing their long-range transport and for evaluating the effectiveness of chemical control initiatives. We report for the first time temporal trends of neutral and ionic PFASs in air from three arctic stations: Alert (Canada, 2006–2014); Zeppelin (Svalbard, Norway, 2006–2014) and Andøya (Norway, 2010–2014). The most abundant PFASs were the perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorobutanoic acid (PFBA), and fluorotelomer alcohols (FTOHs). All of these chemicals exhibited increasing trends at Alert with doubling times (t2) of 3.7 years (y) for PFOA, 2.9 y for PFOS, 2.5 y for PFBA, 5.0 y for 8:2 FTOH and 7.0 y for 10:2 FTOH. In contrast, declining or non-changing trends, were observed for PFOA and PFOS at Zeppelin (PFOA, half-life, t1/2 = 7.2 y; PFOS t1/2 = 67 y), and Andøya (PFOA t1/2 = 1.9 y; PFOS t1/2 = 11 y). The differences in air concentrations and in time trends between the three sites may reflect the differences in regional regulations and source regions. We investigate the source region for particle associated compounds using the Lagrangian particle dispersion model FLEXPART. Model results showed that PFOA and PFOS are impacted by air masses originating from the ocean or land. For instance, PFOA at Alert and PFOS at Zeppelin were dominated by oceanic air masses whereas, PFOS at Alert and PFOA at Zeppelin were influenced by air masses transported from land.
Elsevier
2018
Unleaded gasoline as a significant source of Pb emissions in the Subarctic
After the phasing out of leaded gasoline, Pb emissions to the atmosphere dramatically decreased, and other sources became more significant. The contribution of unleaded gasoline has not been sufficiently recognized; therefore, we evaluated the impact of Pb from unleaded gasoline in a relatively pristine area in Subarctic NE Norway. The influence of different endmembers (Ni slag and concentrate from the Nikel smelter in Russia, PM10 filters, and traffic) on the overall Pb emissions was determined using various environmental samples (snow, lichens, and topsoils) and Pb isotope tracing. We found a strong relationship between Pb in snow and the Ni smelter. However, lichen samples and most of the topsoils were contaminated by Pb originating from the current use of unleaded gasoline originating from Russia. Historical leaded and recent unleaded gasoline are fully distinguishable using Pb isotopes, as unleaded gasoline is characterized by a low radiogenic composition (206Pb/207Pb = 1.098 and 208Pb/206Pb = 2.060) and remains an unneglectable source of Pb in the region.
Pergamon Press
2018
2018
Uptake and effects of 2, 4, 6 - trinitrotoluene (TNT) in juvenile Atlantic salmon (Salmo salar)
Elsevier
2018
2018
2018
Accurate gas velocity measurements in emission plumes are highly desirable for various atmospheric remote sensing applications. The imaging technique of UV SO2 cameras is commonly used to monitor SO2 emissions from volcanoes and anthropogenic sources (e.g. power plants, ships). The camera systems capture the emission plumes at high spatial and temporal resolution. This allows the gas velocities in the plume to be retrieved directly from the images. The latter can be measured at a pixel level using optical flow (OF) algorithms. This is particularly advantageous under turbulent plume conditions. However, OF algorithms intrinsically rely on contrast in the images and often fail to detect motion in low-contrast image areas. We present a new method to identify ill-constrained OF motion vectors and replace them using the local average velocity vector. The latter is derived based on histograms of the retrieved OF motion fields. The new method is applied to two example data sets recorded at Mt Etna (Italy) and Guallatiri (Chile). We show that in many cases, the uncorrected OF yields significantly underestimated SO2 emission rates. We further show that our proposed correction can account for this and that it significantly improves the reliability of optical-flow-based gas velocity retrievals.
In the case of Mt Etna, the SO2 emissions of the north-eastern crater are investigated. The corrected SO2 emission rates range between 4.8 and 10.7 kg s−1 (average of 7.1 ± 1.3 kg s−1) and are in good agreement with previously reported values. For the Guallatiri data, the emissions of the central crater and a fumarolic field are investigated. The retrieved SO2 emission rates are between 0.5 and 2.9 kg s−1 (average of 1.3 ± 0.5 kg s−1) and provide the first report of SO2 emissions from this remotely located and inaccessible volcano.
2018
2018
2018
Water column distribution of mercury species in permanently stratified aqueous environments
Biogeochemical structures of three permanently stratified waterbodies were studied: a sea water basin (the Black Sea), an estuary (Hunnbunn fjord), and a freshwater lake (Nordbytjernet), with focus on the distributions of methylmercury (MeHg) and total mercury (THg). THg concentrations were similar in the sea water basin (0.2–1.8 ng/L) and the freshwater lake (0.8–1.2 ng/L), but significantly higher in the estuary (0.6–9.4 ng/L). An increase in the MeHg concentration and MeHg/THg ratio were found in the redox zone in all three basins, indicating bacterial production of MeHg in the aqueous phase. In the lake and estuary, the maximum MeHg concentration and MeHg/THg ratio were found in samples located closest to the bottom sediments, likely due to the formation of MeHg in surface sediments and subsequent diffusion to the overlying waters.
Springer
2018
Low concentrations of persistent organic pollutants (POPs) in air at Cape Verde
Ambient air is a core medium for monitoring of persistent organic pollutants (POPs) under the Stockholm Convention
and is used in studies of global transports of POPs and their atmospheric sources and source regions. Still,
data based on active air sampling remain scarce in many regions. The primary objectives of this study were to
(i) monitor concentrations of selected POPs in air outside West Africa, and (ii) to evaluate potential atmospheric
processes and source regions affecting measured concentrations. For this purpose, an active high-volume air
sampler was installed on the Cape Verde Atmospheric Observatory at Cape Verde outside the coast of West
Africa. Sampling commenced in May 2012 and 43 samples (24 h sampling) were collected until June 2013. The samples were analyzed for selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB) and chlordanes. The concentrations of these POPs at Cape Verde were generally low and comparable to remote sites in the Arctic for several compounds. Seasonal trends varied between compounds and concentrations exhibited strong temperature dependence for chlordanes. Our results indicate
net volatilization fromthe Atlantic Ocean north of Cape Verde as sources of these POPs. Air mass back trajectories
demonstrated that air masses measured at Cape Verdewere generally transported fromthe Atlantic Ocean or the North African continent. Overall, the low concentrations in air at Cape Verde were likely explained by absence of major emissions in areas from which the air masses originated combined with depletion during long-range atmospheric
transport due to enhanced degradation under tropical conditions (high temperatures and concentrations of hydroxyl radicals).
Elsevier
2018
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2017