Comparison of long-term PM2.5 carbon measurements at an urban and rural location in New York

In order to provide consistency for PM2.5 carbon data across urban and rural areas in the United States the Chemical Speciation Network (CSN) carbon sampling and analysis protocols were changed to resemble those of the Interagency Monitoring of Protected Visual Environments (IMPROVE). The “new” CSN carbon sampler, the URG-3000N, was introduced into the network in May 2007. In this paper collocated carbon measurements are used to (1) check for equivalency between the URG-3000N and the IMPROVE and (2) compare the URG-3000N and IMPROVE data with other collocated measurements. A sufficiently extensive dataset (over several years) enabled comparisons to be performed on a seasonal basis. The URG-3000N provided consistent measurements of PM2.5 carbon with the IMPROVE at both urban and rural locations. In contrast measurements by the CSN MetOne were higher by approximately 20–30% for total carbon at the urban location and 40–50% at the rural location. This information is important for assessing discontinuities in time series data due to changes in the method as occurred to the CSN carbon in 2007.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (82 K)Download as PowerPoint slideHighlights► Several PM2.5 carbon methods are compared at an urban and rural location. ► URG-3000N and IMPROVE PM2.5 carbon are consistent at both locations. ► Seasonal differences between IMPROVE PM2.5 carbon and other methods are explored. ► Total carbon (TC) differences from 20 to 50% are observed. ► TC differences are attributed to a dynamic particle-gas phase equilibrium.