A series of measurements of total gaseous mercury (TGM) made over the Atlantic Ocean in 1977–1980, 1990, and 1994 has been continued by measurements made on board the research vessel (RV)
Polarstern ...during three cruises: from Bremerhaven to Punta Quilla (October–November 1996), Bremerhaven–Cape Town–Antarctica–Cape Town (December 1999–March 2000), and Antarctica–Punta Arenas (February 2001). The data from these cruises are presented and compared with the data from previous cruises. In both hemispheres the average and median TGM concentrations in 1996 and 2000 were comparable to those measured in 1977–1980 but substantially lower than those observed in 1990. TGM measurements on board ships proved to provide a valuable complementary information to measurements by a ground based monitoring network since they show a large-scale distribution and can provide information about sources of mercury and its long-range transport in areas not covered by the present monitoring network.
Monitoring of atmospheric mercury concentrations has been carried out at the Mace Head atmospheric research station on the west coast of Ireland between September 1995 and December 2001. Measurements ...were carried out with a time resolution of
15
min
. No trend in the concentration levels has been detected during the measurement period, with the annual average concentrations remaining constant at
1.75
ng
m
−3
. A slight increase in the concentration levels is derived, if only clean sector filtered air masses clearly of marine origin are used.
The Mace Head data set shows a seasonal pattern with higher monthly mean concentrations in the winter months. Comparison with two continental sites in Sweden shows, that atmospheric mercury concentrations at the western inflow boundary are on an average higher than those at the two continental sites, expressing a west to east decreasing concentration gradient.
At Mace Head, no indications for so-called Mercury Depletion Events (MDEs), recently reported for a number of sites in the Arctic and in the Antarctic, have been found between 1995 and 2001.
As part of an international Hg flux intercomparison at the Steamboat Springs, Nevada, geothermal area, several dynamic soil flux chambers and micrometeorological gradient systems were operated over ...desert soils in early September 1997. A series of unanticipated convective rain cells impacted the site with the first rainfall in ∼90 days, and the initial 4‐cm rainfall increased soil moisture from ∼0.01 to 0.06% (vol/vol). Several chambers were operating prior to the events, and two were deployed over wet soils following rainfall. Rainfall resulted in an immediate and steep rise in ambient air Hg concentrations and soil Hg emissions which persisted for 12–24 hours. Fluxes increased most quickly and to a greater degree over the wettest soils, and the rate of increase was related to chamber design and flushing rate. The flux response was also apparent in the micrometeorological data. In general, soil emissions increased by an order of magnitude following the rain, and reached levels ∼6 times above those at the same time the previous day. These fluxes were significantly correlated with temperature, radiation, humidity, wind speed, and soil moisture. After drying for ∼40 hours, selected soil plots were manually irrigated with low‐Hg‐distilled water. Mercury emissions responded similarly across the three treated sites, uniformly increasing from ∼60 ng m−2 h−1 pretreatment to ∼650 ng m−2 h−1 posttreatment, which was a factor of ∼6 higher than adjacent control soils. Possible causes of the increases in flux include soil gas displacement, desorption of Hg° by water molecules, and desorption of Hg(II) and subsequent reduction in solution. The kinetics of the flux response, combined with local soil and climatic conditions, suggest that Hg emissions were responding primarily to soil moisture and solar radiation. These data have interesting implications for the role of changing regional climates on biogeochemical cycling of Hg.
Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg ...pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos.eu) and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010-2015), analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.
A panel of international experts was convened in Madison, Wisconsin, in 2005, as part of the 8th International Conference on Mercury as a Global Pollutant. Our charge was to address the state of ...science pertinent to source attribution, specifically our key question was: “For a given location, can we ascertain with confidence the relative contributions of local, regional, and global sources, and of natural versus anthropogenic emissions to mercury deposition?” The panel synthesized new research pertinent to this question published over the past decade, with emphasis on four major research topics: long-term anthropogenic change, current emission and deposition trends, chemical transformations and cycling, and modeling and uncertainty. Within each topic, the panel drew a series of conclusions, which are presented in this paper. These conclusions led us to concur that the answer to our question is a “qualified yes,” with the qualification being dependent upon the level of uncertainty one is willing to accept. We agreed that the uncertainty is strongly dependent upon scale and that our question as stated is answerable with greater confidence both very near and very far from major point sources, assuming that the “global pool” is a recognizable “source.” Many regions of interest from an ecosystem-exposure standpoint lie in between, where source attribution carries the greatest degree of uncertainty.
Neutral volatile and semi-volatile polyfluorinated organic compounds (PFC) and ionic perfluorinated compounds were determined in air samples collected at two sites in the vicinity of Hamburg, ...Germany, and onboard the German research vessel Atair during a cruise in the German Bight, North Sea, in early November 2007. PUF/XAD-2/PUF cartridges and glass fiber filters as sampling media were applied to collect several fluorotelomer alcohols (FTOH), fluorotelomer acrylates (FTA), perfluoroalkyl sulfonamides (FASA), and perfluoroalkyl sulfonamido ethanols (FASE) in the gas- and particle-phase as well as a set of perfluorinated carboxylates (PFCA) and sulfonates (PFSA) in the particle-phase. This study presents the distribution of PFC in ambient air of the German North Sea and in the vicinity of Hamburg for the first time. Average total PFC concentrations in and around Hamburg (180
pg m
−3) were higher than those observed in the German Bight (80
pg m
−3). In the German Bight, minimum–maximum gas-phase concentrations of 17–82
pg m
−3 for ΣFTOH, 2.6–10
pg m
−3 for ΣFTA, 10–15
pg m
−3 for ΣFASA, and 2–4.4
pg m
−3 for ΣFASE were determined. In the vicinity of Hamburg, minimum–maximum gas-phase concentrations of 32–204
pg m
−3 for ΣFTOH, 3–26
pg m
−3 for ΣFTA, 3–18
pg m
−3 for ΣFASA, and 2–15
pg m
−3 for ΣFASE were detected. Concentrations of perfluorinated acids were in the range of 1–11
pg m
−3. FTOH clearly dominated the substance spectrum; 8:2 FTOH occurred in maximum proportions. Air mass back trajectories, cluster, and correlation analyses revealed that the air mass origin and thus medium to long range atmospheric transport was the governing parameter for the amount of PFC in ambient air. Southwesterly located source regions seemed to be responsible for elevated PFC concentrations, local sources appeared to be of minor importance.
Polyfluorinated compounds (PFCs) were investigated in waste water treatment plant (WWTP) effluents and surface waters of the River Elbe from samples collected in 2007. Concentrations of various PFCs, ...including C4–C8 perfluorinated sulfonates (PFSAs), C6 and C8 perfluorinated sulfinates, 6:2 fluorotelomer sulfonate, C5–C13 perfluorinated carboxylic acids (PFCAs), C4 and C8 perfluoroalkyl sulfonamides and 6:2, 8:2 and 10:2 unsaturated fluorotelomercarboxylic acids were quantified. ∑PFC concentrations of the river water ranged from 7.6 to 26.4ngL−1, whereas ∑PFC concentrations of WWTP effluents were approximately 5–10 times higher (30.5–266.3ngL−1), indicating that WWTPs are potential sources of PFCs in the marine environment. PFC patterns of different WWTP effluents varied depending on the origin of the waste water, whereas the profile of PFC composition in the river water was relatively constant. In both kinds of water samples, perfluorooctanoic acid (PFOA) was the major PFC, whereas perfluorobutane sulfonate (PFBS) was the predominant PFSA.
We examined recent atmospheric mercury concentrations measured with a high temporal resolution of 15 min at Mace Head, a GAW station on the
western coast of Ireland. We attributed a direct ...contribution of 34 % (0.44 ng m−3) to primary sources. Additionally, a steep decline (0.05 ng yr−1) in mercury concentrations was observed between 2013 and 2018. Using a stereo algorithm we reconstructed 99.9 % of the atmospheric mercury. A conservative analysis demonstrated no decrease in total gaseous mercury (TGM) associated with atmospheric species typically used as tracers for oceanic emissions. The results show that the atmospheric mercury mass is mainly loaded in
a baseline factor with an ongoing decline. Moreover, we exploit temporal variation and wind pattern effects in the measured atmospheric species; the results show that the diurnal variation and seasonality in TGM observed in Mace Head are closely related to other species linked to primary sources and can be explained by transport from continental areas.
Total body burden and tissue distribution of polyfluorinated compounds (PFCs) were investigated in harbor seals (
Phoca vitulina) from the German Bight in 2007. A total number of 18 individual PFCs ...from the following groups could be quantified in the different tissues: perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs) and their precursors perfluorinated sulfinates (PFSiAs), perfluorinated sulfonamides, and sulfonamido ethanols. Perfluorooctanesulfonate (PFOS) was the predominant compound in all measured seal tissues (up to 1665
ng
g
−1 wet weight in liver tissue). The dominant PFCAs were perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), but their concentrations were much lower compared to PFOS. The mean whole body burden in harbor seals of all detected PFCs was estimated to be 2665
±
1207
μg absolute. The major amount of the total PFCs burden in the bodies was in blood (38%) and liver (36%), followed by muscle (13%), lung (8%), kidney (2%), blubber (2%), heart (1%), brain (1%), thymus (<0.01%) and thyroid (<0.01%). These data suggest large differences in body burden and accumulation pattern of PFCs in marine mammals.
The concentration of atmospheric mercury was measured on 13 June 1996, during a level flight from Munich to Halle at an altitude of 900
m a.s.l. and back at 2500
m a.s.l. Measurements, corrected for ...pressure dependence of the instrument response, showed that, with the exception of the southernmost part of the return flight with higher concentrations, mercury was horizontally evenly distributed over a distance of 400
km. The total gaseous mercury (TGM) concentration at an altitude of 2500
m a.s.l. (in the free troposphere) was with 1.635±0.094
ng
m
−3 (
n=22) slightly lower than at 900
m a.s.l. (in the mixing layer) with 1.774±0.101
ng
m
−3 (
n=17). Higher TGM concentrations of 2.190±0.255
ng
m
−3 (
n=2) during the southernmost part of the flight south of Munich and of 2.321±0.133
ng
m
−3 (
n=8) at the summit of the mountain Wank was attributed to a different air mass. Substantially higher TGM concentrations were observed in the mixing layer downwind of a former chlor–alkali plant at Schkopau. From the downwind/upwind concentration difference and the prevailing wind conditions, a mercury emission of about 0.4
kg
d
−1 was estimated for the plant area.
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