Overview of NO2 pollution level in the lower Danube basin during DANS measurements campaign

Abstract

The aim of this paper is to quantify the NO2 level in the lower Danube basin area based on measurements using a mobile DOAS (Differential Optical Absorption Spectroscopy) system. The DOAS system used in this study is composed of an UV-Vis spectrometer for recording the sunlight spectra mounted on a car, as mobile platform. Mobile DOAS measurements were performed in October 2018 around and inside the cities of Galati, Braila, Tulcea, in rural areas and remote areas that are far from cities and other major sources of nitrogen oxide, in order to observe how the pollution level varies in the case of these zones. The measurement tracks show the NO2 distribution in different zones of the lower Danube basin. The values of the NO2 tropospheric densities are extracted from measurements of the mobile DOAS system by using a simple approach. Thus, all the measurements were performed at noon, when the sunlight path is almost perpendicular to the ground surface and therefore, the performed measurements are more sensitive in detecting the vertical column densities (VCD) of trace gases from the troposphere. A GIS (Geographic Information System) software was used to plot the results of the measurements as spatial distribution maps for each track.