Significant climate change has been detected in Southeastern Romania (SERO) in recent decades. This region also suffers from the influence of different pollution sources. Therefore, the spatial and temporal variations in the particulate matter PM10 and PM2.5 and trace gases (NO₂, CO, SO₂, and O₃) in the atmosphere of different zones of this region need to be analyzed.
We studied time series of the above major air pollutants' mass concentrations, measured by the national air quality monitoring network (RAQMN) in the southeastern area of Romania. The data are from 59 locations (12 urban traffic, 14 urban background, 8 urban industrial, 4 suburban traffic, 8 suburban background, 8 suburban industrial, 4 rural background, and 1 rural industrial site). For the short-term variations, we used data from 2018 to the present, while for the long-term analysis regarding trend identification and quantification, we used a time period as long as currently possible, as the data were provided by the RAQMN.
The temporal pattern analysis and other statistical analyses were performed using R software with the Openair package. The temporal trend analysis was performed using the Mann–Kendall approach and Theil-Sen's slope method. The univariate spatial analysis (LISA clusters and Moran’s I) was performed using the GeoDa software package.
Among the key findings, we include the identification of a so-called O₃ weekday–weekend effect in a mid-size petrochemical city, according to which the temporal patterns in O₃ precursors (elevated VOCs despite the reduced NOx during weekends); themain pollution sources, through a Principal Component Analysis; and different levels of spatial interactions were identified, which proved to be pollutant-dependent.
The present work provides important insights into the variations in major air pollutants in the SERO area that have not been identified in previous studies, in the larger context of defining new pollution abatement strategies at the local and regional scales.
