PM10 and PM2.5 composition over the Central Black Sea: origin and seasonal variability

Koçak, M.; Mihalopoulos, N.; Tutsak, E.; Theodosi, C.; Zarmpas, P.; Kalegeri, P.

PM10 and PM2.5 composition over the Central Black Sea: origin and seasonal variability

2015

Daily PM₁₀ and PM₂.₅ samples were collected between April 2009 and July 2010 at a rural site (Sinop) situated on the coast of the Central Black Sea. The concentrations of PM₁₀ and PM₂.₅ were 23.2 ± 16.7 and 9.8 ± 6.9 μg m⁻³, respectively. Coarse and fine filters were analyzed for Cl⁻, NO₃ ⁻, SO₄ ²⁻, C₂O₄ ²⁻, PO₄ ³⁻, Na⁺, NH₄ ⁺, K⁺, Mg²⁺, and Ca²⁺ by using ion chromatography. Elemental and organic carbon content in bulk quartz filters were also analyzed. The highest PM₂.₅ contribution to PM₁₀ was found in summer with a value of 0.54 due to enhanced secondary aerosols in relation to photochemistry. Cl⁻, Na⁺, and Mg²⁺ illustrated their higher concentrations and variability during winter. Chlorine depletion was chiefly attributed to nitrate. Higher nssCa²⁺ concentrations were ascribed to episodic mineral dust intrusions from North Africa into the region. Crustal material (31 %) and sea salt (13 %) were found to be accounted for the majority of the PM₁₀. The ionic mass (IM), particulate organic matter (POM), and elemental carbon (EC) explained 13, 20, and 3 % of the PM₁₀ mass, correspondingly. The IM, POM, and EC dominated the PM₂.₅ (~74 %) mass. Regarding EU legislation, the exceeded PM₂.₅ values were found to be associated with secondary aerosols, with a particular dominance of POM. For the exceeded PM₁₀ values, six of the events were dominated by dust while two and four of these exceedances were caused by sea salt and mix events, respectively.

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