Abstract
Atmospheric measurements of nitrogen oxides (NOx = NO + NO2), ozone (O3) and other constituents were carried out during three field campaigns (29 March–30 April 2010, 1–26 April 2011, 18 May–8 October 2015) at Ny-Ålesund. The study focused on the variability of important O3 precursors, such as NOx, in the Arctic troposphere, and on the impact from anthropogenic sources on their measured concentrations: higher NO and NO2 levels were mostly associated with the lowest wind speeds and northern directions, indicating local pollution. Long-range transported sources from Russia and Europe were also identified with an occurrence of high NOx levels. Several ozone depletion events were observed and associated to winds blowing from the north-west direction (Arctic Ocean). Most of these events were connected to the lower NO and NO2 concentrations. Measurements of halogen and low molecular weight carbonyl compounds in 2010 and 2011, respectively, showed variable effects during the ozone depletion events. Other data, such as high time-resolved radon progeny measurements, were used in 2015 to identify source tracking and transport of air masses, local effects and atmospheric stability dynamics that could influence the NOx concentrations at Ny-Ålesund.
Highlights
Nitrogen oxides (NOx = NO + NO2 ) play a critical role in the oxidizing capacity of the troposphere through their impact on the production of radical species (OH, HO2 and RO2 )and ozone (O3 )
Calibrations were performed every 24 h to determine the sensitivity of the instrument using a National Institute of Standards and Technology (NIST)-certified standard of NO in nitrogen (Scott-Marin, Inc., Riverside, CA, USA)
In 2010 in two ways: first, all data were reported in the present study to quantify the impact of local pollution sources on NOx measurements
Summary
The main sources of NOx in the troposphere are fossil fuel combustion, biomass burning, microbial activity in the soil and lightning. The sources of nitrogen oxides in the Arctic regions are different from those of other regions because of the Arctic’s sparse population and its distance from human activities. Anthropogenic pollution in the Arctic originates primarily from Europe and North America or from boreal or agricultural fires. Sources of anthropogenic pollution within the Arctic regions (e.g., vehicle emissions, domestic heating, shipping, oil and gas and petroleum extraction, metal smelting and mineral extracting [2,3]) are important, but they are poorly quantified. Natural emissions from boreal forest fires, vegetation (tundra and forests), ocean, volcanic eruptions, resuspended dust from volcanic ash sediments and glacial deposits are important sources of air pollutants [3]. Several studies have demonstrated that nitrate (NO3− ) photolysis in the snowpack under sunlight conditions is a local and natural source of NOx [4]
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