| Abstract [eng] |
INTRODUCTION The Earth's climate system is influenced in complex ways by aerosol particles, including organic, inorganic and carbonaceous components. Higher concentrations of these aerosol particles have a significant impact on the climate in rural, urban and coastal areas. These various aerosols play a crucial role in atmospheric processes that influence weather and affect air quality. To address uncertainties, it is crucial to comprehensively understand the chemical composition, sources, formation, transformations, and dynamic interactions of aerosol particles within the Earth's climate system. Recent studies in Western and Southern Europe have comprehensively characterized aerosol sources, especially in urban and rural areas. Despite this extensive knowledge, the Baltic region, particularly Eastern Europe, has seen limited studies, marking a significant gap in our understanding. The present study aims to fill this gap by presenting a comprehensive, long-term approach focusing on the chemical composition of organic, inorganic and carbonaceous aerosol particles in the rural environment of boreal forests (North-Eastern part) and the urban environment of Lithuania. This includes leveraging local studies and datasets to provide a regional perspective that enhances our understanding of aerosol dynamics in these areas. The objective is to enhance knowledge about pollution seasonality, source variability, and their implications for decision-makers. Similarly, in the Philippines, the research focuses on the critical issue of black carbon (BC) pollution in urban and coastal areas. While previous research has made significant progress in characterizing aerosol particles in terms of size distribution, concentration, and spatial variability, knowledge gaps persist, particularly in understanding BC sources other than road activity and the impact of the Manila Port on aerosol levels. This research aims to provide new insights into these areas, contributing to our understanding of the complex atmospheric mechanisms that regulate aerosol composition and distribution as well as their influence on climate change. THE MAIN AIM AND TASKS The objective of this study was to identify the main sources of organic, inorganic, and carbonaceous aerosol particles and compare their properties across rural, urban, and coastal environments. To achieve this objective, the following tasks were established: • Characterization of organic, inorganic and carbonaceous aerosol particles in rural, urban and coastal environments. • Source apportionment of carbonaceous aerosol particles in rural, urban and coastal environments. • Evaluation of the impact of meteorological conditions on organic, inorganic and carbonaceous aerosol particles in rural, urban and coastal environments. NOVELTY A key novelty of this study lies in the comparative analysis carried out in the urban environments of Northern Europe and South Asia, which allowed identification of a consistent relative contribution of brown carbon to carbonaceous aerosol across geographically and climatically distinct regions, despite differences in biomass burning sources driven by seasonal and socioeconomic factors, i.e. domestic heating in Lithuania and agricultural residue burning in the Philippines. DEFENSIVE STATEMENTS 1. Organic aerosols (OA) were the dominant component across rural, urban, and coastal environments (53 – 80%). Inorganic aerosols (SO₄²⁻, NO₃⁻, NH₄⁺, and Cl⁻) remained lower than OA throughout the study, indicating a consistent dominance of organics in the composition of atmospheric aerosol particles regardless of environmental differences. 2. Black carbon (eBC) originating from fossil fuel combustion and the transport sector was the dominant source (contributing 80 – 90%) in rural, urban, and coastal environments. In contrast, biomass burning accounted for a significantly lower share (10 – 20%), confirming the larger impact of traffic and fossil fuel sources on eBC levels across different environments. 3. In rural, urban and coastal environments, brown carbon (BrC) accounted for only 14 – 22% of the total composition of carbonaceous aerosol. Biomass burning is the main source of BrC and has a relatively smaller impact on air quality comparing to other dominant of eBC, such as fossil fuel combustion and transport emissions. 4. eBC and BrC concentrations in Northern European urban environment is 14 – 15 times lower than in South Asian urban environments, but the relative contribution of fossil fuel and biomass combustion sources remains similar (4% difference) regardless of geographical location and season of the year. WORK RELEVANCE Characterizing the chemical components of atmospheric submicron aerosols in rural, urban, and coastal environments is important due to their adverse effects on human health and their significant influence on the Earth’s climate system. Therefore, it is crucial to deepen our understanding of aerosol chemical composition and the pathways of their formation. The results of this study could enhance our understanding of atmospheric chemistry at both local and global scales. Additionally, it highlights the persistent black carbon (BC) pollution in developing regions and calls for scientifically based strategies to mitigate the air quality crisis. CONCLUSIONS 1. The mean hourly average mass concentrations of NR-PM1 at Rugšteliškis, Vilnius, and Manila port were 8.48 μg/m³, 18.98 μg/m³, and 29.52 μg/m³, respectively. Mean hourly average mass concentrations of eBC at Rugšteliškis, Vilnius, Quezon, and Manila Port reported as 0.60 μg/m³, 2.46 μg/m³, 36.19 μg/m³, and 10.27 μg/m³, respectively. The comparative analysis revealed significant spatial variations in NR-PM1 and eBC concentrations, with Quezon City showing the highest levels, followed by Manila North Port, Vilnius, and the lowest in Rūgšteliškis. Seasonal variations showed higher NR-PM1 concentration (9.07 μg/m³) in spring and higher eBC concentration (0.72 μg/m³) in autumn at the Rūgšteliškis rural site, with particularly high eBC in Quezon urban (36 μg/m³) and Manila Port (10 μg/m³) during winter. 2. The diurnal trend analysis of NR-PM1 and eBC across different environments reveals significant variations driven by the interplay of anthropogenic activities and natural atmospheric conditions. In rural areas, morning peaks of OA and eBC reflect emissions from biomass burning and vehicular traffic, along lower boundary layer height. Urban environments show more pronounced diurnal peaks due to high traffic and industrial activities, especially during morning and evening rush hours. In coastal areas, the diurnal patterns are similarly influenced by local traffic, port activities, and atmospheric conditions such as wind speed and boundary layer dynamics. 3. The comprehensive source apportionment analysis reveals that the dominant source of eBC at Rūgšteliškis, Vilnius, Quezon, and Manila North Port originated from fossil fuel and transport-related emissions, accounting for 90%, 85%, 81%, and 86% respectively. Although lesser, the contribution of biomass burning to eBC underscores the influence of local practices such as residential heating and agricultural burning. The contribution of BrC was 14%, 18%, 22%, and 20% at Rūgšteliškis, Vilnius, Quezon, and Manila North Port, respectively. The minor but notable presence of BrC, primarily from biomass burning, varies spatially with local practices such as domestic cooking, agricultural residue burning, and seasonal activities, impacting light absorption characteristics. 4. Both local sources and long-range transport significantly impacts the concentrations of NR-PM1 and eBC at rural, urban, and coastal sites. Specifically, at the rural site of Rūgšteliškis, higher concentrations were associated with wind directions from south and west. In Vilnius, elevated levels correlated with wind directions from the west and east. At the QCG site, higher eBC concentrations were linked to wind directions from the east, while at the Port site, elevated levels were tied to wind directions from west. |
