GAW Report No. 205 - IGAC Project

CHAPTER 4 – SOUTH AMERICAMaximum SO 2 concentrations measured in the 1970s were 90% lower than the air qualitystandards. Therefore, SO 2 was considered a pollutant of non-concern in the region and within aminimal budget for air quality monitoring the environmental authorities decided againstsystematically measuring this pollutant. This decision has remained until present. The availableSO 2 concentration data come from different measurement campaigns undertaken mostly in the late90s [e.g., Bogo et al., 2001]. However the increasing use of liquid fuels in both mobile sources,including ships, and power plants have the potential to revert the present low levels towardsincreasing values. Therefore, it may be advisable to include SO 2 in future air quality monitoringstrategies.The few measurements of O 3 concentrations in the MABA region have been undertaken byacademia. The results show that 1-hour concentrations do not exceed the standards of the City ofBuenos Aires. In accordance with ground level ozone chemistry, O 3 and NO concentrations areinversely correlated, with O 3 concentrations being lower in areas with high vehicular traffic.Because of the small size of the sample, the O 3 situation in the region cannot be assessed.In line with worldwide trends, monitoring of particles in the MABA evolved from measuringtotal suspended particulate matter (TSP) to PM 10 and more recently PM 2.5 . Measurements of TSPwere carried out mostly by governmental agencies while those of PM 10 and PM 2.5 were carried outby research groups that have been interested in a number of issues such as assessing the impactof specific sources, characterizing multi-elemental aerosol composition, and source identificationthrough receptor models. PM 10 levels are relatively high, although 24-hour concentrations do nottypically exceed the air quality standard. The monthly average PM 10 levels are in some casesclose to or slightly higher than 50 µg/m 3 . PM 2.5 levels are typically high with 24-hour concentrationsclose to or relatively higher than the air quality standard of the City of Buenos Aires whilst monthlyaverages are twice the strict limit established by the US air quality standards. Mass concentrationsof PM 10 levels increase from the inner part of the city towards the La Plata river shore while PM 2.5 isthe size fraction more homogeneously distributed. The influence of the adjacent ocean is apparentin terms of sea salt and halogens [Dos Santos et al., 2009].Lead concentrations in particulate matter were reported in three different studies [Caridi etal., 1989; Ozafrán et al., 1999; Smichowski et al., 2004]. The two latter studies show thedecreasing levels of this metal with respect to those measured in the first study, reflecting thephase out of the use of lead alkyl additives to gasoline enforced in Argentina since 1995.Until recently, no consistent emission inventory was available for Buenos Aires. The firstsystematic attempt is described in D'Angiola et al. [2010]. This inventory refers to on-road mobilesources of MABA and reports emissions for the period 2000-2006 of greenhouse gases (CO 2 , CH 4and N 2 O) and criteria pollutants (CO, NOx , NMVOCS, PM and SO 2 ) disaggregated by district andalso presented in a grid of 1x1 km 2 using a distribution algorithm described by Saide et al. [2009b].The same research group is now developing the inventory for stationary sources [Oreggioni, 2009].According to these data, on-road vehicles are the main contributors for almost all of the pollutantsin MABA with the only exception of SO 2 and CO 2 , for which stationary sources are dominant.Compared to other cities in South America, the existent relatively high emission rates fromMABA are generally not perceived as an environmental threat due to the atmospheric conditionthat rapidly vent the MABA. Nevertheless, the large population density of Buenos Aires constitutesa risk as more population is exposed to pollution, increasing the probability of health impacts. Inaddition, the strong ventilation and vertical mixing of the MABA, the tenth largest megapolis of theworld, is subject to impact long-range transport of pollution from Buenos Aires.4.4 LIMA, PERULima, Peru is located at 12˚3’S and 77°3’˚W at an altitude of 110 m.a.s.l with a populationof ~9 million inhabitants. The quasi-permanent subtropical Pacific high and the Chilean-Peruvianoceanic current determine largely the climate of Lima, which is arid with an annual precipitation of153