| 1. |
- Sprovieri, F., et al.
(författare)
-
Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network
- 2016
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:18, s. 11915-11935
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 2. |
- Angot, H., et al.
(författare)
-
Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models
- 2016
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:16, s. 10735-10763
-
Tidskriftsartikel (refereegranskat)abstract
- Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission). Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011-2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and inter-annual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.
|
|
| 3. |
- Gårdfeldt, Katarina, 1959, et al.
(författare)
-
Evasion of Mercury from coastal and open waters of the Atlantic ocean and the Mediterranean sea
- 2003
-
Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1
-
Tidskriftsartikel (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) was measured in coastal Atlantic seawater and in the Mediterranean Sea. The Atlantic measurements were performed during September 1999 at the Mace Head Atmospheric Research Station, situated on the Irish west coast. The measurements in the Mediterranean Sea were made along a 6000 km cruise path from 14 July to 9 August 2000 in the framework of the Med-Oceanor project. Total gaseous mercury (TGM) concentrations in air were continuously measured with a 5 min time resolution using an automated mercury analyser (Tekran 2537A) during both expeditions. Paired TGM and DGM samples from all campaigns showed that the surface water was supersaturated with elemental mercury. The mercury evasion was estimated using a gas exchange model (J. Geophys. Res. 97 (1992) 7373), which uses salinity, wind speed and water temperature as independent parameters. The predicted average mercury evasion from the coastal Atlantic water was 2.7 ng m−2 h−1 implying that the concentration of TGM in the Atlantic air is enhanced by mercury evasion from the sea. Measurements in different regions of the Mediterranean Sea showed spatial variations in DGM concentrations. The highest DGM concentration (90 pg l−1) was observed at a location in the Strait of Sicily (37°16N 11°52E). The mercury evasion in the eastern sector of the Mediterranean Sea (area: 32–36°N, 17–28°E) was generally higher (7.9 ng m−2 h−1) than that observed in the Tyrrhenian Sea (4.2 ng m−2 h−1) or in the western sector (2.5 ng m−2 h−1) (areas: 38–42°N, 8–13°E and 38–41°N, 7–8°E, respectively). Estimations of mercury evasion were also made at Mediterranean coastal sites using a dynamic chamber technique. In addition, a newly developed method making continuous in situ DGM measurements possible was tested.
|
|
| 4. |
- Andersson, Maria, 1980, et al.
(författare)
-
Seasonal and daily variation of mercury evasion at coastal and off shore sites from the Mediterranean Sea
- 2007
-
Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 104:3-4, s. 214-226
-
Tidskriftsartikel (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hg-extr / H', Hg-extr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March-April 2004 and October-November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hg-extr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600-1150%) was observed during the summer. The spring showed the lowest variation (260-360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500-1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P. S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air-sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(l):373-387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m(-2) h(-1). The summer value was estimated to 22.3 pmol m(-2) h(-1) and the spring to 7.6 pmol m(-2) h(-1). Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons. (C) 2006 Elsevier B.V. All rights reserved.
|
|
| 5. |
- Coccioni, Rodolfo, et al.
(författare)
-
Integrated stratigraphy of the Lutetian-Priabonian pelagic section at Bottaccione (Gubbio, central Italy) : A proposal for defining and positioning the Global Stratotype Section and Point (GSSP) for the base of the Bartonian Stage (Paleogene System, Eocene Series)
- 2022
-
Ingår i: From the Guajira Desert to the Apennines, and from Mediterranean Microplates to the Mexican Killer Asteroid : Honoring the Career of Walter Alvarez - Honoring the Career of Walter Alvarez. - : Geological Society of America. - 0072-1077. - 9780813795577 - 9780813725574 ; 557
-
Bokkapitel (refereegranskat)abstract
- At present, the Global Stratotype Section and Point (GSSP) for the base of the Bartonian remains the only GSSP of the Paleogene System to be defined by the International Subcommission on Paleogene Stratigraphy (ISPS) and the International Commission on Stratigraphy (ICS). Here, we present the results of an integrated, high-resolution study of calcareous plankton and benthic foraminifera biostratigraphy and a detailed magneto-, chemo-, and cyclostratigraphic analyses carried out through the upper Lutetian to the upper Priabonian pelagic sediments of the Bottaccione Gorge section near Gubbio, central Italy, to check its stratigraphic completeness and constrain in time the optimal interval for defining and positioning the GSSP for the base of the Bartonian Stage. The high-resolution and solid integrated stratigraphic framework established at Bottaccione confirmed the completeness of the section, which meets the ICS recommendations for a potential designation as a GSSP for the base of the Bartonian Stage. Thus, the Bottaccione section was compared with the parastratotype section of the Bartonian in its type area, Alum Bay, UK. On this basis, two reliable criteria for defining and positioning the Bartonian GSSP at Bottaccione are provided: (1) the base of magnetic polarity chronozone C18r as the primary correlation criterion and (2) the base of the calcareous nannofossil Dictyococcites bisectus, which defines the CNE14/CNE15 zonal boundary as a secondary correlation criterion.
|
|
| 6. |
|
|
| 7. |
- Mulder, M. D., et al.
(författare)
-
Air-sea exchange and gas-particle partitioning of polycyclic aromatic hydrocarbons in the Mediterranean
- 2014
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus Publications. - 1680-7316 .- 1680-7324. ; 14:17, s. 8905-8915
-
Tidskriftsartikel (refereegranskat)abstract
- Polycyclic aromatic hydrocarbon (PAH) concentration in air of the central and eastern Mediterranean in summer 2010 was 1.45 (0.30-3.25) ng m(-3) (sum of 25 PAHs), with 8 (1-17) % in the particulate phase, almost exclusively associated with particles <0.25 mu m. The total deposition flux of particulate PAHs was 0.3-0.5 mu g m(-2) yr(-1). The diffusive air-sea exchange fluxes of fluoranthene and pyrene were mostly found net-depositional or close to phase equilibrium, while retene was net-volatilisational in a large sea region. Regional fire activity records in combination with box model simulations suggest that seasonal depositional input of retene from biomass burning into the surface waters during summer is followed by an annual reversal of air-sea exchange, while interannual variability is dominated by the variability of the fire season. One-third of primary retene sources to the sea region in the period 2005-2010 returned to the atmosphere as secondary emissions from surface seawaters. It is concluded that future negative emission trends or interannual variability of regional sources may trigger the sea to become a secondary PAH source through reversal of diffusive air-sea exchange.Capsule: In late summer the seawater surface in the Mediterranean has turned into a temporary secondary source of PAH, obviously related to biomass burning in the region.
|
|
