Abstract

Optical detectors for atmospheric aerosol concentration measurements are often used inair quality applications given their potentialities for online measurements of air qualityparameters at high temporal resolution. In this work the performances of different opticalaerosol detectors used in air quality applications have been tested and compared for urbanbackground aerosol conditions. Simultaneous measurements of aerosol number concentrations,size distributions and mass concentrations were taken in two different periods:November 2013 - February 2014 and May-June 2014 at an urban background site inLecce (Southeastern Italy). Measurements were carried out using an OPC Grimm (mod.1.109), an OPC FAI (Multichannel Monitor) and an optical photometer Mie pDR-1200.Good correlation, with determination coefficients R2 larger than 0.93 were found betweenparticle number concentrations measured by the two OPCs both in accumulation (0.28-0.90 lm for FAI and 0.29-0.90 lm for Grimm) and coarse modes (1.10-10 lm for FAIand 1.15-11.25 lm for Grimm). Absolute counting for the accumulation fraction showsthat Grimm OPC detects more particles (about 10%) than FAI OPC at concentration higherthan 200,000 particles/L in condition of high RH. This could be due to the changes of theoptical properties of particles in high RH conditions visible even if the inlets of the twoinstruments are conditioned for lowering RH in sampled air. The differences in the absolutecounting of the coarse fraction does not seems to be related to RH effects. The performancesin evaluating mass concentrations PM10, and PM2.5 were evaluated comparingOPCs and pDR-1200 outputs with reference gravimetric and b-ray methods (that appearedto be essentially equivalent). Good agreement between Grimm OPC and SWAM is foundboth in PM10 and PM2.5 fractions while FAI OPC revealed greater discrepancy and scatterwith respect to reference measurements. The performances of the pDR-1200 photometerwere lower with respect to the OPCs with a larger influence of RH and optical propertiesof particles. The analysis of diurnal average trends in number and mass concentrationsas well as the high temporal resolution responses of the instruments showed that opticaldetectors could be very useful to investigate atmospheric aerosol for air quality applicationsand to individuate and investigate specific pollution events. However, especially ifthey are used for evaluating mass concentrations (PM1, PM2.5 or PM10), it is necessary to take into account RH effects (even if the inlet are conditioned) and, possibly, use opticaldetectors together with reference gravimetric or b-ray methods to check their response inthe effective operative conditions.

Autore Pugliese

• Donateo Antonio , Contini Daniele

Tutti gli autori

• A. Dinoi; A. Donateo; F. Belosi; M. Conte; D. Contini

Titolo volume/Rivista

Measurement

Anno di pubblicazione

2016

ISSN

0263-2241

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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