资源环境科技发展态势分析平台

European emissions data have been reported during the last 40 years under the Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP), launched by the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP). In this paper, long-term continuous data of gaseous and particulate air pollutants concentrations measured over a period of 36 years (1981–2017) from a coastal background EMEP air quality monitoring site in Preila, Lithuania, were analyzed. All the analyzed S- and N- species decreased during the 1981–2017 period except for nitrate concentration, which increased during the 1990s by 170%, and showed minor decreasing trend during the 2000–2017 period.

The analysis has shown that despite the 95% and 79% decrease of sulfur dioxide and sulfate concentrations, respectively, sulfate comprised a considerable share of the ion balance. As the concentration of total sulfate decreased remarkably, the sea-related particles portion of the sulfate concentration increased up to 22%. The sulfur dioxide concentration at the Preila station has stabilized since 2015. Separation between the time series of sulfur dioxide and sulfate occurred in 2007–2008 with sulfate exceeding sulfur dioxide concentrations during the latest decade. This indicates the absence of local sulfur dioxide sources and relative increase in contributions by long-range transport of particulate forms of sulfur.