Effect of the Shutdown of a Coal-Fired Power Plant on Urban Ultrafine Particles and Other Pollutants

摘要

Ultrafine particle (UFP) monitoring over the size range of 10-500 nm has been ongoing in Rochester, New York, since November 2001. A nearby large coal-fired power plant (CFPP) was shut down in the spring of 2008 for conversion to natural gas combustion. This shutdown resulted in a reduction in observed concentrations of UFP number and other pollutants. In this study, positive matrix factorization (PMF) model and conditional probability function (CPF) were used to elicit the CFPP source information based on 2005-2010 hourly concentration data of particles and gaseous species and meteorological variables. Five factors were identified, i.e., nucleation, regional transport, traffic, CFPP, and O₃-rich secondary aerosol that influenced the measured pollution levels. The average 10-50 nm, 50-100 nm, and 100-500 nm particle number concentrations decreased 49.8%, 51.9%, and 52.9% from 2007 to 2008, respectively. The annual average SO₂, CO, and PM_2.5 concentrations also decreased by 64.1%, 39.6%, and 45.6% from 2007 to 2008, respectively. The largest reductions of 10-50 nm particles, CO, and SO₂ concentrations between 2007 and 2009 were observed with northerly winds. These changes were clearly attributed to the shutdown of the large CFPP in the study area.