Development and Characterization of a Time-Sequenced Cascade Impactor: Application to Transient PM2.5 Pollution Events in Urbanized and Industrialized Environments

Abstract

To set up a sampling and analysis strategy for particulate matter (PM) based on the time periods used in international standards is often inadequate for assessing the impact of day/night cycles or episodic emissions on urban air quality. To obtain a detailed physico–chemical characterization of urban PM when concentrations exceed the regulatory thresholds, a new rotary cascade impactor named the Time-Resolved Atmospheric Particle Sampler (TRAPS) was designed and tested for coarse and fine particle sampling. The TRAPS implementation, coupled with Optical Particle Counter measurements, provides time-resolved samples that can be analyzed by a wide range of single-particle analysis techniques. The TRAPS theoretical design was verified experimentally. Experimental cut-off diameters of 1.32 and 0.13 µm, respectively, for coarse and fine stages, were found in good agreement with theoretical values. Additionally, good trace separation, preventing inter-sample contamination, was evidenced by Scanning Electron Microscopy (SEM). The homogeneous distribution of particles of different types over a trace was also verified. As a case study, automated SEM-EDX analysis of 2500 particles, collected during two pollution peaks of a transient PM2.5 pollution event, revealed that individual particles’ chemical composition was influenced by local sources during the first pollution peak, and mainly transported during the second peak.

Atomic spectrometry update – a review of advances in environmental analysis

“…The Versatile Aerosol Concentration Enrichment System (VACES) enabled 17 simultaneous sampling of ultrafine particles both on filters and in a liquid suspension for subsequent chemical and toxicity measurements. The Time Resolved Atmospheric Particle Sampler (TRAPS) coupled 18 a rotary cascade impactor to an OPC so that both coarse particles (1 μm) and fine particles (0.1 μm) could be monitored at high temporal resolution.…”

“…The carbonate was decomposed to CO 2 which was collected under a controlled atmosphere for offline analysis. A comparison of isotopic data for carbonate zones analysed both by classical methods (micro-drilling followed by acid digestion) and the new laser calcination method gave correlation coefficients of 0.99 for d 13 C and 0.96 for d 18 O for a range of different mineralogies and isotopic compositions. As well as decreasing the overall analytical time considerably by reducing the number of preparation steps, the new procedure offered the possibility of performing spatially resolved analysis at the mm scale.…”

Optimization Study of Sampling Device for Semi-Volatile Oil Mist in the Industrial Workshop

“…Common equipment for aerosol separation includes the diffuser, the inertial impactor, and the virtual impactor [27][28][29][30][31][32]. In the case of the diffuser, since the diffusion coefficients of particles and gas in the diffusion tube are different, separation is achieved as the gas diffuses to the tube wall and the particles flow out through the tube.…”