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The accumulation of trace elements in the thalli of epiphytic lichens can reveal levels of trace elements in the ambient air. This study assessed the trace elements in lichen species Pyxine cocoesfound in the urban and peri-urban areas of Kolkata. Trace elemental analysis was carried out using energy-dispersive X-ray fluorescence and proton-induced X-ray emission spectroscopy. Variable levels of elements like Mn, Fe, Cu, Zn, Cr, V and Pb, are detected in the thalli of P. cocoescollected from repressentative locations. Localization of trace elements in the thalli was confirmed by analysis using scanning electron microscope attached with EDX spectrometer. Several pollution indices such as enrichment factor, contamination factor (Cf) and pollution load index were estimated to evaluate the trace element contamination level of the ambient air at the sampling spots. PLI and Cf and values suggest deterioration or air quality that varies from moderate to high level of contamination. Ca, S, Pb, Sr and Cr, are highly enriched at urban sampling spots (1–9). High coefficient of variation values for Ca, S, Pb, Sr and Cr confirm their accumulation from local anthropogenic sources in the urban sampling spots (1–9). However, results of principal component analysis analysis have shown that sources of trace elements in the samples from urban areas include both vehicular emissions and anthropogenic activities. Higher concentration of trace elements in the lichen thalli collected from peri-urban locations is attributed to vehicular emissions from the highways and expressways running through these areas.

This study presents measurements of aerosol chemical properties at Sonla, northern Vietnam (675 m a.s.l.) during spring time, when biomass burning (BB) was very active in the northern Indochina Peninsula, as part of the 7-SEAS (Seven South East Asian Studies) campaign in 2013. The gas chromatography-mass spectrometry (GC-MS) analysis of BB markers in 14 selected samples indicated that mixed softwood, hardwood, grass, and non-woody vegetation were burned. More than 50 organic compounds including levoglucosan, lignin and resin products, sugar and sugar alcohol compounds, fatty acids, phthalate esters, aromatic acids, poly-acids, and biogenic oxidation products (e.g., 2-methyltetrols, alkene triols, 3-hydroxyglutaric acid) were measured in PM2.5. Levoglucosan, a BB tracer, was the predominant species among aerosol sugars, with an average concentration of 1.62 ± 0.89 µg m−3, comprising 2.23 ± 0.5% of PM2.5mass. For the collection period of the selected samples, backward air mass trajectories were classified into the source regions of Indochina (BBIC), southern China (BBSC), and the South China Sea (BBSS). All resolved molecular compounds show their dominance on the trajectory from BBIC, verifying the BB smoke origin of that region. Trajectory classification provides additional information, such as higher level of diethyl phthalate associated with BBSC trajectory, revealing urban or industrial influence, and more low-molecular-weight than high-molecular-weight fatty acids, indicating distributions with more microbial and lesser plant wax/vegetation burning contributions along the BBSC trajectory. In addition, we report, for the first time, stable carbon isotopic data (δ13C) for PM2.5aerosols in northern Vietnam, which ranged from –26.6 to –25.4‰ in PM2.5, indicating contributions from burning of C3plants and fossil fuel combustion.