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A dual-inlet, single detector relaxed eddy accumulation system for long-term measurement of mercury flux

Osterwalder, Stefan and Fritsche, Johannes and Alewell, Christine and Schmutz, Michael and Nilsson, Mats and Jocher, Georg and Sommar, Jonas and Rinne, Janne and Bishop, Kevin. (2016) A dual-inlet, single detector relaxed eddy accumulation system for long-term measurement of mercury flux. Atmospheric Measurement Techniques, 9. pp. 509-524.

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Official URL: http://edoc.unibas.ch/44565/

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Abstract

The fate of anthropogenic emissions of mercury (Hg) to the atmosphere is influenced by the exchange of elemental Hg with the earth surface. This exchange holds the key to a better understanding of Hg cycling from local to global scales, which has been difficult to quantify. To advance research about land-atmosphere Hg interactions, we developed a dual-inlet, single detector relaxed eddy accumulation ( REA ) system. REA is an established technique for measuring turbulent fluxes of trace gases and aerosol particles in the atmospheric surface layer. Accurate determination of gaseous elemental mercury (GEM) fluxes has proven difficult due to technical challenges presented by extremely small concentration differences (typically < 0.5 ngm(-3)) between updrafts and downdrafts. We present an advanced REA design that uses two inlets and two pairs of gold cartridges for continuous monitoring of GEM fluxes. This setup reduces the major uncertainty created by the sequential sampling in many previous designs. Additionally, the instrument is equipped with a GEM reference gas generator that monitors drift and recovery rates. These innovations facilitate continuous, autonomous measurement of GEM flux. To demonstrate the system performance, we present results from field campaigns in two contrasting environments: an urban setting with a heterogeneous fetch and a boreal peatland during snowmelt. The observed average emission rates were 15 and 3 n gm(-2) h(-1), respectively. We believe that this dual-inlet, single detector approach is a significant improvement of the REA system for ultra-trace gases and can help to advance our understanding of long-term land-atmosphere GEM exchange.
Faculties and Departments:05 Faculty of Science
05 Faculty of Science > Departement Umweltwissenschaften
05 Faculty of Science > Departement Umweltwissenschaften > Umweltgeowissenschaften
05 Faculty of Science > Departement Umweltwissenschaften > Umweltgeowissenschaften > Umweltgeowissenschaften (Alewell)
UniBasel Contributors:Alewell, Christine and Schmutz, Michael and Osterwalder, Stefan
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:European Geosciences Union
ISSN:1867-1381
e-ISSN:1867-8548
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:31 Oct 2017 07:28
Deposited On:31 Oct 2017 07:28

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