The spatial distribution of polyfluoroalkyl compounds (PFCs) and their composition profile was investigated in 48 water samples collected from the German Bight. All samples were prepared by ...solid-phase extraction with Strata XAW cartridges and analysed using high performance liquid chromatography/negative electrospray ionisation–tandem mass spectrometry (HPLC/(−)ESI–MS/MS). Concentrations of various PFCs, including perfluorinated sulfonates (PFSAs), perfluorinated carboxylic acids (PFCAs), unsaturated fluorotelomercarboxylic acids, perfluoralkyl sulfonamide and sulfonamidoethanol, were quantified. The ∑PFC concentration ranges from 9.36
ng
L
−1 to 31.2
ng
L
−1, while perfluorobutane sulfonate (PFBS, 3.38–17.7
ng
L
−1) and perfluorooctanoic acid (PFOA, 2.67–7.83
ng
L
−1) dominated. The rivers Elbe, Weser and Ems had a high influence on the distribution of most PFCs in the German Bight, with maximum PFC concentrations found in their estuaries, and concentrations decreasing with increasing distance from the coast. Conversely, PFBS had its maximum concentration not in the estuaries but in the western German Bight, which suggest an additional source, where PFBS was transported into the German Bight with the westerly current.
Many emission inventories for mercury have been compiled but rarely constrained using observations of ambient air concentrations with a known quality. In this paper, we derive Hg/CO, Hg/halocarbon, ...and Hg/CH
4 emission ratios from pollution episodes observed during the long-term mercury monitoring at the Mace Head Atmospheric Research Station in Ireland. The average Hg/CO emission ratio from 15 pollution episodes with air originating from the European continent observed between 1996 and 2003 was 0.0050±0.0021
ng
m
−3
ppbv
−1, i.e. (5.5±2.3)×10
−7
mol/mol, which is almost identical to the ratio reported recently for the continental plumes of eastern Asia. Mercury correlated also with CFCl
3 (CFC-11), CF
2Cl
2 (CFC-12), CH
3CCl
3, CCl
4, CCl
2FCF
2Cl (CFC-113), CHCl
3, N
2O, and CH
4 during the pollution episodes. The mercury emissions calculated from the emission ratios and the European emissions of the above gases are in reasonable agreement with the estimated anthropogenic total mercury emissions of 250
t/yr in 1995. However, the measurements encompass almost exclusively elemental mercury whose anthropogenic emissions are estimated to be only 152
t
yr
−1. Several hypotheses are proposed to explain this discrepancy, such as natural sources, underestimation of the emissions of elementary mercury, and erroneous speciation of anthropogenic emissions.
Temporal trends of polyfluoroalkyl compounds (PFCs) were examined in liver samples from harbor seals (
Phoca vitulina) collected from the German Bight (1999–2008). Concentrations of various PFCs, ...including C
4–C
10 perfluoroalkyl sulfonates (PFSAs), perfluorooctane sulfinate (PFOSi), perfluorooctane sulfonamide (FOSA) and C
8–C
15 perfluoroalkyl carboxylic acids (PFCAs) were quantified. Perfluorooctane sulfonate (PFOS) was the predominant compound with a maximum concentration of 3676
ng
g
−1 ww (1996), making up on average 94% of the measured PFCs. Significantly higher concentrations were found in <7 month old in comparison to ⩾7 month old harbor seals for C
6–C
8 PFSAs, perfluorododecanoic acid (PFDoDA) and FOSA, whereas perfluorodecanoic acid (PFDA) showed significantly lower concentrations in the younger harbor seals (
p
<
0.05). These results suggest a transplacental transfer of PFCs to the foetus and/or consumption of different contaminated food. Regression analysis of logarithmic transformed PFC mean concentrations indicated a significant temporal trend with decreasing concentrations for C
5–C
7 PFSAs (
p
<
0.001), PFOSi (
p
=
0.028), FOSA (
p
<
0.001) and perfluorooctanoic acid (PFOA) (
p
=
0.031) between 1999 and 2008. Furthermore, PFOS decreased by 49% between 1999 and 2008, which correspond with decreasing concentration levels of its metabolic precursors PFOSi and FOSA of 83% and 95% in the same time period. However, the decreasing trend of PFOS is not significant (
p
=
0.067). The reason for the decline during the past 10 years could be an effect of the replacement of these PFCs by shorter chained and less bioaccumulative compounds. But the observations of increasing perfluorodecane sulfonate (PFDS) levels (
p
=
0.070), the high concentrations of PFOS and constant levels of C
9–C
13 PFCAs indicates that further work on the reduction of environmental emissions of PFCs are necessary.
The global monitoring plan of the Minamata Convention on Mercury was established to generate long-term data necessary for evaluating the
effectiveness of regulatory measures at a global scale. After ...25 years of monitoring (since 1995), Mace Head is one of the atmospheric monitoring stations with the longest mercury record and has produced sufficient data for the analysis of temporal trends of total gaseous mercury (TGM) in Europe and the North Atlantic. Using concentration-weighted trajectories for atmospheric mercury measured at Mace Head as well as another five
locations in Europe, Amderma, Andøya, Villum, Waldhof and Zeppelin, we identify the regional probabilistic source contribution factor and its changes for the period of 1996 to 2019. Temporal trends indicate that concentrations of mercury in the atmosphere in Europe and the North Atlantic have declined significantly over the past 25 years at a non-monotonic rate averaging 0.03 ngm-3yr-1. Concentrations of TGM at remote marine sites were shown to be
affected by continental long-range transport, and evaluation of reanalysis back trajectories displays a significant decrease in TGM in continental air masses from Europe in the last 2 decades. In addition, using the relationship between mercury and other atmospheric trace gases that could serve as
a source signature, we perform factorization regression analysis, based on positive rotatable factorization to solve probabilistic mass functions. We reconstructed atmospheric mercury concentration and assessed the contribution of the major natural and anthropogenic sources. The results reveal that the observed downward trend in the atmospheric mercury is mainly associated with a factor with a high load of long-lived anthropogenic species.
Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric ...chemistry, and air–surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM ∕ GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM ∕ GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation. Hence, the performance of the Hg oxidation mechanisms under study differs in the extent to which they can reproduce the various observed parameters. This variation implies possibility of more complex chemistry and multiple Hg oxidation pathways occurring concurrently in various parts of the atmosphere.
Mercury species in air have been measured at five sites in Northwest Europe and at five coastal sites in the Mediterranean region during measurements at four seasons. Observed concentrations of total ...gaseous mercury (TGM), total particulate mercury (TPM) and reactive gaseous mercury (RGM) were generally slightly higher in the Mediterranean region than in Northwest Europe. Incoming clean Atlantic air seems to be enriched in TGM in comparison to air in Scandinavia. Trajectory analysis of events where high concentrations of TPM simultaneously were observed at sites in North Europe indicate source areas in Central Europe and provide evidence of transport of mercury on particles on a regional scale.
The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal ...depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.
Long-term measurements of gaseous elemental mercury (GEM) concentrations at Cape Point, South Africa, reveal a downward trend between September 1995 and December 2005 and an upward one from March ...2007 until June 2015, implying a change in trend sign between 2004 and 2007. The trend change is qualitatively consistent with the trend changes in GEM concentrations observed at Mace Head, Ireland, and in mercury wet deposition over North America, suggesting a change in worldwide mercury emissions. Seasonally resolved trends suggest a modulation of the overall trend by regional processes. The trends in absolute terms (downward in 1995–2004 and upward in 2007–2015) are highest in austral spring (SON), coinciding with the peak in emissions from biomass burning in South America and southern Africa. The influence of trends in biomass burning is further supported by a biennial variation in GEM concentration found here and an El Niño–Southern Oscillation (ENSO) signature in GEM concentrations reported recently.
The Mace Head dataset comprises the longest existing time series of atmospheric mercury measurements with high time resolution in the temperate marine background atmosphere, starting in September ...1995. For this study, the concentrations of total gaseous mercury in baseline air masses arriving at Mace Head, Ireland have been analyzed for possible trends in the atmospheric mercury background concentration over a 16-year period (i.e., 1996–2011). Statistical analyses have revealed a significant negative (downwards) trend of −0.027 +/− 0.01 ng/m3 yr−1, or −1.4 to 1.8% per year. Furthermore, evidence of a seasonal cycle was found with somewhat higher concentrations during the winter time and somewhat lower concentrations during summer.
Since January 2009 highly time-resolved mercury speciation measurements in ambient air are carried out at the Central European German EMEP monitoring station and measurement site of the German ...Federal Environment Agency “Waldhof“, providing the longest Central European dataset for mercury species. First statistical analyses do not indicate long term trends for the concentrations of gaseous elemental mercury (GEM) and particle bound mercury (TPM). A potential increasing trend for reactive gaseous mercury (RGM) will have to be verified in the coming years and should be regarded as indicative only at present. A seasonal cycle for TPM could be observed with higher concentrations during winter time. Furthermore a diurnal cycle for RGM is apparent with highest concentrations in the early afternoon.
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