Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-1036
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Dec 2016
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Four years (2011–2015) of Total Gaseous Mercury measurements from the Cape Verde Atmospheric Observatory
Katie A. Read1, Luis M. Neves2, Lucy J. Carpenter1, Alastair C. Lewis1, Zoe Fleming3, and John Kentisbeer4 1National Centre for Atmospheric Science (NCAS), Department of Chemistry, University of York, York, YO10 5DD, UK
2Instituto Naçional de Meteorologia Geofisica (INMG), Delegãço de São Vicente, Monte, CP15, Mindelo, Rep of Cape Verde
3National Centre for Atmospheric Science (NCAS), University of Leicester, Leicester, LE1 7RH, UK
4Centre for Ecology and Hydrology (CEH), Bush Estate, Penicuik, Midlothian, EH26 0QB, UK
Abstract. Mercury is a chemical with widespread anthropogenic emissions that is known to be highly toxic to humans, ecosystems and wildlife. Global anthropogenic emissions are around 20 % higher than natural emissions and the amount of mercury released into the atmosphere has increased since the industrial revolution. In 2005 the European Union and United States adopted measures to reduce mercury use, in part to offset the impacts of increasing emissions in industrialising countries. The changing regional emissions of mercury have impacts on a range of spatial scales. Here we report four years (Dec 2011–Dec 2015) of Total Gaseous Mercury (TGM) measurements at the Cape Verde Observatory (CVO), a global WMO-GAW station located in the sub-tropical remote marine boundary layer. Observed total gaseous mercury concentrations were between 1.03 and 1.33 ng m−3 (10th, 90th percentiles), close to expectations based on previous interhemispheric gradient measurements. We observe a decreasing trend in TGM (0.04 ± 0.03 ng m−3 yr−1, −3.4 % ± 2.4 % yr−1) over the four years consistent with the reported decrease of mercury concentrations in North Atlantic surface waters and reductions in anthropogenic emissions. The trend was more visible in the summer (Jul–Sep) than in the winter (Dec–Feb), when measurements were impacted by air from the African continent and Sahara/Sahel regions. African air masses were also associated with the highest and most variable TGM concentrations. We suggest that the less pronounced downward trend in African air may be attributed to poorly controlled anthropogenic sources such as artisanal and small-scale gold mining (ASGM).

Citation: Read, K. A., Neves, L. M., Carpenter, L. J., Lewis, A. C., Fleming, Z., and Kentisbeer, J.: Four years (2011–2015) of Total Gaseous Mercury measurements from the Cape Verde Atmospheric Observatory, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1036, in review, 2016.
Katie A. Read et al.
Katie A. Read et al.
Katie A. Read et al.

Viewed

Total article views: 155 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
116 29 10 155 4 14

Views and downloads (calculated since 06 Dec 2016)

Cumulative views and downloads (calculated since 06 Dec 2016)

Viewed (geographical distribution)

Total article views: 155 (including HTML, PDF, and XML)

Thereof 155 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 26 Mar 2017
Publications Copernicus
Download
Short summary
This paper presents four years of total gaseous mercury data obtained from measurements made at the Cape Verde Atmospheric Observatory, a subtropical site in the Atlantic Ocean. The data shows a clear decreasing trend in the overall concentrations but in air from sub-saharan Africa the trend is less significant and the data more variable. We attribute this result to an influence from artisanal small-scale gold mining in this region, a source for which there is uncertain information.
This paper presents four years of total gaseous mercury data obtained from measurements made at...
Share