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Environ Sci Pollut Res Int. 2019 Oct;26(28):29334-29350. doi: 10.1007/s11356-019-06117-7. Epub 2019 Aug 8.

Inter-comparison of carbon content in PM10 and PM2.5 measured with two thermo-optical protocols on samples collected in a Mediterranean site.

Author information

1
Institute of Atmospheric Sciences and Climate, ISAC-CNR, Str. Prv. Lecce-Monteroni km 1.2, 73100, Lecce, Italy. e.merico@isac.cnr.it.
2
Institute for the Dynamics of Environmental Processes, IDPA-CNR, Via Torino 155, 30172, Venice Mestre, Italy.
3
Institute of Atmospheric Sciences and Climate, ISAC-CNR, Str. Prv. Lecce-Monteroni km 1.2, 73100, Lecce, Italy.
4
Department of Environmental Sciences, Informatics and Statistics (DAIS), Ca' Foscari University of Venice, Via Torino 155, 30172, Venice Mestre, Italy.
5
Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100, Lecce, Italy.
6
Department of Economics, Management and Business Law, University of Bari Aldo Moro, Largo Abbazia Santa Scolastica 53, 70124, Bari, Italy.
7
Department of Chemistry, University of Bari Aldo Moro, Via Orabona 4, 70125, Bari, Italy.

Abstract

Scientific interest is focusing on different approaches for characterising organic carbon (OC), elemental carbon (EC) and equivalent black carbon (eBC), although EUSAAR2 protocol has been established and frequently used in EU for regulatory purposes. Discrepancies are observed due to thermal protocols used for OC/EC determinations and the effect of the chemical-physical properties of aerosol using optical measurements for eBC. In this work, a long-term inter-comparison of carbon measurements with two widely used protocols (EUSAAR2 and NIOSH870) was performed on PM2.5 and PM10 samples. The influence of the protocol on the evaluation of secondary organic aerosol (SOC) and on the correlation between EC and eBC was investigated. An extensive check of repeatability gave typical uncertainties of ~ 5% for TC and OC, and ~ 10% for EC for both thermal protocols. Results show that OC is statistically comparable between the two protocols but EC is significantly higher with EUSAAR2, especially during the warm season. The ratio OC/EC is lower with EUSAAR2, also showing a seasonality (lower values in the warm season) not observed with NIOSH870. Despite the differences in OC/EC ratios, the contribution of SOC to OC (~ 50%), evaluated using the EC-tracer method, did not differ significantly between the two protocols and for both size fractions. Further, SOC/OC ratios were comparable in cold and warm periods. eBC/EC ratios larger than one for both protocols were obtained, 1.62 (EUSAAR2) and 1.92 (NIOSH870), and also correlated with the ratio OC/EC for both protocols, especially in the cold season.

KEYWORDS:

EC; EUSAAR2; NIOSH870; OC; Thermo-optical protocols; eBC

PMID:
31396867
DOI:
10.1007/s11356-019-06117-7
[Indexed for MEDLINE]

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