Comparison of Carbonaceous Aerosols in Tokyo before and after Implementation of Diesel Exhaust Restrictions

Abstract

We compared the status of carbonaceous aerosols in Tokyo before and after the implementation of a diesel vehicle regulation intended to reduce the quantity of particulate carbon from diesel engines in one of the largest scale ever attempts at vehicle exhaust control. Radiocarbon (14C) in elemental carbon (EC) and total carbon (TC) were analyzed to identify fossil fuel carbonaceous particles emitted from diesel-powered vehicles. One-sided paired-month t-tests showed no distinct difference in the absolute concentrations of particles in terms of total mass (19.5 to 18.0 microg m(-3); p = 0.321), EC (3.6 to 3.3 microg m(-3); p = 0.272), and TC (6.3 to 6.2 microg m(-3); p = 0.418) for the finest particles (d(a) < 1.1 microm) after the implementation of the regulation. The ratios of the concentrations of the chemical constituents were, however, altered after the regulation. EC/TC was significantly decreased from 56.7% to 50.2% (p = 0.039). Although it was not statistically significant, the percentage of fossil carbon in EC also decreased (67.8% to 63.8%; p = 0.104). Since EC is predominantly of combustion origin, the observed decrease was likely due to the decrease in fossil EC emissions from diesel-powered vehicles. The decrease in EC/TC after the implementation of the regulation was also likely to have resulted from attachment to diesel vehicle exhaust systems of particulate filters as required as part of the regulation by the Tokyo Metropolitan Government. The EC/TC of fossil carbon of the finest particles decreased from 66.2% to 55.2% (p = 0.066), but EC/TC of biomass carbon did not decrease but rose slightly from 43.6% to 44.5% (p > 0.5). Thus, the relative ratios of components of carbonaceous aerosol particles, such as 14C, could provide a better understanding of the atmospheric pollution status, despite short-term fluctuations, than do measurements of absolute concentrations.

Aerosol Absorption and Scattering Measurements: Field Measuremnets and Laboratory Characterizations.

“…Heald et al (2008) compiled all the gas and particle phase organic measurements into the newly defined "Total Observed Organic Carbon", which had a daytime mean of 456ugCm-3 at TO and 17ugCm-3 for the C-130. The TO levels are an order-of-magnitude higher than those measured in Pittsburgh (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45), while those measured in the C-130 are typical of polluted airmasses in the US sampled from aircraft. The organic aerosol PM contribution increased from -3% of the TOOC at TO to 9% for the C-130, due to SOA formation and the larger contribution of biomass burning to regional airmasses.…”

“…During the MCMA-2006 field campaign, air flow trajectories within the Mexico City basin and the fate of the urban plume were simulated, and five types of wind circulation patterns were identified : Cold Surge, South Venting, 0 3 -North, 0 3 -South, and Convection (North and South). During the 31 days of the MCMA-2006 field campaign, three were Cold Surge (14,21,23 March), eight were South Venting (1)(2)(3)(4)(5)(6)(7)13 March), five were 03-South (8,12,(15)(16)(17), seven were 03-North (9)(10)(11)(18)(19)(20)22 March), and eight were Convection (24)(25)(26)(27)(28)(29)(30)(31). The prevailing meteorological conditions can strongly influence ambient pollutant concenti'ations for given emission levels and also determine the regional impacts of the urban plume .…”

“…Gaffney, NA. Marley / Atmospheric Environment 43 (2009) [23][24][25][26][27][28][29][30][31][32][33][34][35][36] States in 1996 due to its extreme toxicity, particularly in children. However, it is still allowed for off-road uses including aircraft, racing cars, farm equipment and marine engines.…”

“…Marley/Atmospheric Envhonment 43 (2009) [23][24][25][26][27][28][29][30][31][32][33][34][35][36] quality in London due to the combustion of coal (Evelyn, 1661). His comments on the effects of air quality included: "...This hoirid Smoake which obscures our Church and makes our Palaces look old, which fouls our Cloth and corrupts the Waters, so as the veiy Rain, and refreshing Dews which fall in the several seasons, precipitate to impure vapour, which, with its black and tenacious quality, spots and contaminates whatever is exposed to it... it is evident to eveiyone who looks on the yearly Bill of Mortality, that near half the children that are born in London die under two years of age.…”

Emission Regulations Altered the Concentrations, Origin, and Formation of Carbonaceous Aerosols in the Tokyo Metropolitan Area

“…It is expected that the characteristics of carbonaceous aerosols in the Tokyo metropolitan area (TMA) will have significantly varied since the introduction of these regulations. Yamamoto et al (2007) (Yamamoto et al, 2007). Fushimi et al (2011) investigated the impacts of biogenic carbon on the mass of secondary organic aerosols (SOA) as well as their diurnal variations at sites outflow from the TMA in the summer of 2007.…”