Abstract. Measurements of gaseous elemental mercury (GEM) fluxes over snow surfaces using a relaxed eddy accumulation (REA) system are carried out at the High Arctic site at the Villum Research Station, Station Nord, in North Greenland. Simultaneously, CO2 fluxes are determined using the eddy covariance (EC) technique. The REA system with dual inlets and dual analyzers is used to measure fluxes directly over the snow. The measurements were carried out from 23 April to 12 May during spring 2016, where atmospheric mercury depletion events (AMDEs) took place. The measurements showed a net emission of 8.9 ng m−2 min−1, with only a few minor episodes of net depositional fluxes, from a maximum deposition of 8.1 ng m−2 min−1 to a maximum emission of 179.2 ng m−2 min−1. The data support the theory that gaseous oxidized mercury (GOM) is deposited during AMDEs followed by formation of GEM on surface snow and is re-emitted as GEM shortly after the AMDEs. Furthermore, observation of the relation between GEM fluxes and atmospheric temperature suggests that GEM emission partly could be affected by surface heating. However, it is also clear that the GEM emissions are affected by many parameters.

Abstract. Emission of ammonia (NH3) is a ubiquitous problem due to the adverse effects of NH3 on the environment and human health. The agricultural sector accounts for nearly all NH3 emissions in Europe. Hence, technologies for the abatement of NH3 emissions from this sector have been in strong demand in recent years. In order to document emissions and evaluate abatement technologies, there is a strong need for reliable NH3 measurement methods. Photoacoustic spectroscopy (PAS) is often used to measure NH3 concentrations, but recent research shows interference from compounds typically present in livestock production and during agricultural activities. In this work, the performance of cavity ring-down spectroscopy (CRDS) from Picarro, as an alternative to PAS, has been tested with respect to method validation under laboratory and field conditions. Potential interferences of 10 volatile organic compounds (VOCs) on CRDS NH3 measurement were tested with simultaneous VOC analysis performed by proton-transfer-reaction mass spectrometry (PTR-MS). Both laboratory and field calibrations show excellent linearity over a large dynamic range of NH3 concentrations. The analyzer shows a small humidity effect of up to a few ppb in the extreme case of a nearly water-saturated air stream. Apart from the negligible humidity dependency, no interferences of the tested VOCs were observed. Overall, the CRDS system performs satisfactory and is well suited for measurements of NH3 emissions from livestock production.

Abstract. Pollution from ammonia (NH3) is a widespread problem due to the effects on the environment and human health. The agricultural sector accounts for nearly all NH3 emissions in Europe; thus, focus has especially been on NH3 emissions from this sector in recent years. We need abatement techniques to reduce NH3 emissions, and in order to evaluate the techniques, there is a strong need for reliable NH3 measurement methods. Photoacoustic spectroscopy (PAS) is often used to measure NH3 concentrations, but recent discoveries show interference from compounds typically present in livestock production and during agricultural activities. We tested the performance of the Cavity Ring-Down Spectroscopy (CRDS) from Picarro for filter effects and laboratory and field calibrations with standard gasses. Furthermore, concentrations of ten volatile organic compounds (VOCs) where determined by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) to test the potential interference of these VOCs. Both laboratory and field calibrations show excellent linearity over a large dynamic range of NH3 concentrations. The analyzer shows a small humidity effect of up to a few ppb in the extreme case of a nearly water saturated air stream. Besides, from the negligible humidity dependence, there is no interference from the tested VOCs. Overall, the system performs well with only negligible influences from other compounds.

No abstract

No abstract