Abstract
The United States has experienced substantial air pollutant emissions reductions in the last two decades. Among others, emissions produced by electricity generation plants and industries were significantly lowered. Ultralow (<15 ppm) sulfur fuels were introduced for road vehicles, nonroad, rail, and maritime transport. New heavy-duty diesel trucks have been equipped with particle traps and NOx controls. Residual oil (No. 6) for space heating and for any other purpose was replaced with cleaner No. 2 and No. 4 oils. Chemical speciation of PM2.5 has been measured since 2005 at eight sites across the New York State. A prior study has identified and apportioned the major sources of PM2.5 across the State using receptor modelling (positive matrix factorization). This present study aims to investigate the long-term trends of those source-apportioned PM2.5 mass contributions from 2005 to 2016 at the eight sites: two rural sites (Pinnacle and Whiteface), three medium sized cities (Buffalo, Albany, Rochester), and three sites in the New York City metropolitan area (Bronx, Manhattan and Queens). Negative trends from 2005 to 2016 were detected across the state for secondary sulfate (from −0.19 μg/m3/y in Rochester to −0.36 μg/m3/y at BRO and QUE) and secondary nitrate (from −0.02 μg/m3/y at the rural sites to approximately −0.2 μg/m3/y at BRO and MAN). Spark-ignition vehicles were the only source type experiencing upward annual trends at all urban sites with slopes ranging from 0.02 μg/m3/y (ROC, not statistically significant) to ∼0.2 μg/m3/y (Albany, Bronx, Manhattan). Other sources exhibited different trends among the sites. The relationships of source contributions with emissions inventories were explored with regression analysis. A new trajectory model, differential concentration-weighted trajectories (DCWT), was used to examine spatial changes in sources of secondary aerosol affecting the rural sites.
Highlights
Starting in the 1970s, many developed countries including the United States implemented air quality management policies to protect human health and the environment
The changes in potential source areas of precursors of secondary sources were evaluated using a new trajectory ensemble method: differential concentration-weighted trajectory (DCWT) analysis. These results provide information on which source emissions were substantially reduced over the past decade, identify those sources that did not change during this period, and identify those sources whose emissions increased
All distilled oil sold in New York State for any purpose were required to be ULSD after July 1, 2012
Summary
Starting in the 1970s, many developed countries including the United States implemented air quality management policies to protect human health and the environment. Since the 1970s, many air pollutant concentrations have declined across the United States (e.g., Hogrefe et al, 2004; Frost et al, 2006; Tagaris et al, 2007; Pye et al, 2009; Dallmann and Harley, 2010; Parrish et al, 2011; Brown-Steiner et al, 2016; Duncan et al, 2016; Nopmongcol et al, 2016; Rattigan et al, 2016; Emami et al, 2018; Masiol et al, 2018a; Squizzato et al, 2018a). Downward trends for the particle number concentrations measured in Rochester have been reported (Masiol et al, 2018a)
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