Investigation of the effects of marine aerosol on the particulate matter pollution in urban atmosphere: A case study in Istanbul

In this study, ion (a set of both trace element and inorganic ions) concentrations of atmospheric aerosols collected along the coastline and in terrestrial regions of Istanbul in accordance with the ASTM-G140 Wet Candle method were measured between April 2011 and October 2011. Similarities and dissimilarities in the chemical compositions of aerosols from various sampling sites were investigated. Aerosol samplings were performed at the stations of Rumeli Feneri, İstinye Emirgan, YTU Maslak, YTU Davutpaşa, Fenertepe, Koç Üniversitesi, Avcılar, Silivri, Yenikapı, Şirinevler, Bakırköy, Kabataş, Levent and Sarıyer which are in the European side of İstanbul; Kadikoy, Bostanci, Maltepe and Büyük Çamlıca Municipal facilities stations which are in the Asian side. Ions (F-, Cl-, NO-2, Br-, NO-3, SO-4, PO-24, Li+, Na+, NH+4, K+, Mg+2, Ca+2) analyses and trace elements (Al, Fe, Ca, Zn, Co, Pb, Ca, Ni, Fe, Mn, Cr, V, Cu, Al, B) analyses were performed by Ion Chromatography and ICP instruments, respectively. Although partially negative effect of wind direction was observed, impact of traffic and industry were also observed on aerosol samples collected from stations in the inner regions. On the other hand, effect of natural sources were predominantly observed in the coastal line of İstanbul. Average Na+ and Cl- fluxes and standard deviation values were determined on the aerosol plume for the Sea of Marmara, the Black Sea and the Bosphorus, and their average values were found to be 34,91±26,27 mg/m2.day and 42,53±43,49 mg/m2.day; 109,82mg/m2.day and 77,69 mg/m2.day; 94,77±94,55 mg/m2.day and 67,48±56,81 mg/m2.day. While aerosol samples were collected on the coastal region of İstanbul in order to examine the marine aerosol formation, aerosol samples were also collected in the inner parts of İstanbul to examine the marine aerosol transportation toward inland areas. Highest and lowest average Na+ and Cl- fluxes and their respective standard deviation ordinarily for; YTU Yıldız, 1,77 km and Levent, 3,3 km away from the Bosphorus were determined to be 24,91±16,09 mg/m2.day and 21,72±12,76 mg/m2.day, 14,81±16,81 mg/m2.day and 14,48±16,27 mg/m2.day Enrichment Factor Analysis (EF) were performed in order to determine sources of parameters. As a result of marine enrichment factor analysis (EF)d fluxes of Na+ ve Cl- were calculated as a close to the values of the affected coastal area of sea surface along the coast of Istanbul (Marmara Sea, Black Sea and Istanbul Bosphorus). EFm values are calculated 1 for Cl- which represent to marine aerosol throughout coastal stations. Marine enrichment was recorded especially summer season in coastal and inland areas of Istanbul. In addition, while fluxes of chromium, lead, nickel, and zinc are generated from anthropogenic sources such as local and regional industries during all study period, fluxes of aluminum, iron, magnesium etc. are reached to Istanbul from natural sources during spring and autumn. At the same time, these results were explained according to effect of local sources on stations and results of Principle Component Analysis (PCA).The results of samples were compared with the results of long range transport obtained from HYSPLIT model. Dust plume were transported from Egypt and Jordan to Turkey on 16 April and 29 September within the sampling period. Satellite maps of this transportations were displayed by NASA's Earth Observatory website. The same dates back to 24-hour HYSPLIT trajectory model was run with an altitude of 500, 750 and 1500 m in order to determine the effects of transportation on aerosol samples. According to the model outputs of both situations, the air masses approaching over Istanbul during both cases came from over Blacksea and not from southeast. Therefore, it was concluded from the compositions of aerosol collcted during those periods that the sources of aerosols were thought to be originated from marine, anthropogenic and soil structures on local scales.Statistical analyses of aerosol compositions showed that, variations of mass flux values were wider in the case of dominant marine originated aerosols and relatively narrower in the case of dominant anthropgenic originated aerosols.