Toward Establishing the Stability of Multi-Year Monitoring of Elements in Airborne Particles

Abstract

Crocker Nuclear Laboratory uses a custom built energydispersive X-ray fluorescence system with a molybdenum anode to provide routine analysis of elements from nickel to zirconium and lead in Interagency Monitoring of Protected Visual Environments (IMPROVE) samples. Standard methods are used to ensure accuracy and statistical control of the data, including repeated analysis of singleelement standards, standard reference materials, and selected actual samples from the IMPROVE network. This paper compares the short-term (week) precision and longterm (2-yr) reproducibility revealed by the actual sample reanalyses. Currently reported analytical uncertainties are shown to predict actual 2-yr reproducibility within a factor of 2.

Assessing the Suitability of Historical PM2.5 Element Measurements for Trend Analysis

“…18 A custom energy-dispersive X-ray fluorescence (EDXRF) system using a Mo-anode excitation tube (Mo XRF) was introduced in June 1992 to obtain better sensitivity for the heavier elements, Fe−Pb. 19 A second, custom EDXRF system with a Cu-anode excitation tube replaced PIXE for the lighter elements, and was used to report Na−Fe starting in December 2001. The analysis chamber of the initial Cu XRF system was flushed with He (Cu XRF, He) to displace atmospheric Ar, which contributes unwanted spectral background.…”

“…Proton induced X-ray emission (PIXE) analysis with the CNL cyclotron was initially used for all the elements . A custom energy-dispersive X-ray fluorescence (EDXRF) system using a Mo-anode excitation tube (Mo XRF) was introduced in June 1992 to obtain better sensitivity for the heavier elements, Fe–Pb . A second, custom EDXRF system with a Cu-anode excitation tube replaced PIXE for the lighter elements, and was used to report Na–Fe starting in December 2001.…”

A Special Issue of JA&WMA on Aerosol and Atmospheric Optics: Visual Air Quality and Radiation

“…Three papers in this issue explore statistical analysis and data quality issues using IMPROVE data. This includes the effect of different methods of estimating precision, 2 the long-term stability of filter samples to nondestructive analyses, 3 and the need to consider particulate sample deposit geometry for accurate face-velocity determination. 4 Whereas the regional haze rule uses 24-hr averaged aerosol data to determine progress toward meeting the national goal of no manmade visibility impairment, large variations in light extinction may occur over periods of a few hours as is demonstrated from analysis of data from the RoMANS study.…”