GAW Report No. 205 - IGAC Project

CHAPTER 6 - EUROPEaddition to local pollution, Istanbul is vulnerable to trans-boundary transport of air pollutants fromEurope, because its location is on the eastern end of the Continent, where westerly winds prevail[Kidnap, 2008].6.7.2.2 Emissions sources of pollutants and their precursors in the areaBetween 1980 and 1990 the consumption ratio of coal to fuel-oil increased from 0.68 (in1980) to 3.09 in 1990 [Tayanc et al., 2000]. Liquefied petroleum gas (LPG) has been widely used intraffic starting from the beginning of 1998. Through the emissions from the transport sector, a bigportion of ozone precursors and aerosols are emitted to the atmosphere. There has been a shiftfrom coal to natural gas for domestic heating purposes starting from the early 1990s, leading to adecrease in the concentrations of primary pollutants such as sulphur oxides (SO x ) but an increasein secondary pollutants such as aerosols and ozone. The region experiences very dense industrialactivities, almost the highest in the country. Almost half of Turkish industry is located around theMarmara Sea [OECD, 2008]. Based on Istanbul Chamber of Industry reports, 37% of the industrialactivities comprise textile industry, 30% metal industry, 21%chemical industry, 5% food industry,and 7% other industries [Im et al., 2006]. Low quality solid and liquid fuels with high sulphur content,natural gas, and LPG are the most commonly used fuel types in the industrial activities. In addition,over 2 million cars circulate in Istanbul, most of them are older cars. Under these the density andvariety of industrial activities, the region experiences very complex air quality conditions.Markakis et al. [2009] have developed an emission process kernel aimed at compiling a highspatial and temporal resolution emission inventory for anthropogenic sources for the GIA at a 2 kmgrid. They considered nitrogen oxides (NO X = NO + NO2), carbon monoxide (CO), SO X , ammonia(NH3), non-methane volatile organic compounds (NMVOCs), PM 10 , and PM 2.5 . They estimated totalannual emissions in the GIA of 437 kt for CO, 305 kt for NO X , 91 kt for SO X , 77 kt for NMVOCs, 7 ktfor NH 3 , 61 kt for PM 10 , and 37 kt for PM 2.5 . Their results indicate that the road transport sector is themain contributor to the emissions in the area, whereas residential and industrial combustion as wellas cargo shipping are also important source categories. Industrial combustion (49% of PM 10 and24% of PM 2.5 ) and road transport (17% of PM 10 and 29% of PM 2.5 ) emissions also play the majorrole in PM emissions. Particularly, 76 % of the organic portion of PM comes from traffic. Energy andindustrial combustion are found to be the main SO X emitters (36 and 23%, respectively). NMVOCsmainly originate from road transport (45%), solvent use (30%), and waste (20%). The spatialdistribution of emissions follows the residential distribution and the seasonal variation shows higheremissions during the winter. Weekend emissions are lower than weekday emissions and diurnalcalculations show that the profile fits with the rush hours due to the highest contribution of trafficemissions [Makrakis et al., 2009].6.7.2.3 Air pollutantsOzone and its precursors - Im et al. [2008] reported O 3 observations from two different locationsin Istanbul close to the Marmara sea from 2001 to 2005. One location, Saraçhane, is on theEuropean side of the city and the other one location, Kadıköy, is the Asian side of the city. Thehighest ozone concentrations were observed during hot, sunny summer when maximumtemperatures were above 25 °C. These episodes were mainly characterized by southwesterlysurface winds during the day and northeasterly surface winds during the night. High VOC-to-NO Xratios at both stations indicated that NO X -sensitive chemistry was dominant in the region. However,higher correlations of VOCs in Kadıköy, as compared with those in Saraçhane, indicated that VOCsalso have an important contribution to ozone formation. High O 3 days demonstrated a typical diurnalprofile with maximum concentrations appearing during afternoon hours and minimumconcentrations appearing during rush hours due to NO X titration from traffic emissions. According tomeasurements, daily average O 3 concentrations were around 100 µg . m −3 whereas individualepisodic periods had hourly concentrations reaching 180 µg . m −3 in Saraçhane and 140 µg . m −3 inKadıköy [Im et al., 2008]. Lower-daily maximum values at the Kadıköy Station resulted from betterventilation due to its location near the sea and from larger titration values of NO X resulting fromclose proximity to dense traffic.236