Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data
Abstract The carbon fractions of organic (OC1, OC2, OC3, OC4, OP) and elemental (EC1, EC2, and EC3) carbon obtained from IMPROVE (Interagency Monitoring of PROtected Visual Environments) thermal/optical carbon analysis of quartz-fiber filters have been implemented to help distinguish spark-ignition...
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| Format: | Article |
| Language: | English |
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Springer
2023-05-01
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| Series: | Aerosol and Air Quality Research |
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| Online Access: | https://doi.org/10.4209/aaqr.230041 |
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| author | Philip K. Hopke Yunle Chen David Q. Rich John G. Watson Judith C. Chow |
| author_facet | Philip K. Hopke Yunle Chen David Q. Rich John G. Watson Judith C. Chow |
| author_sort | Philip K. Hopke |
| collection | DOAJ |
| description | Abstract The carbon fractions of organic (OC1, OC2, OC3, OC4, OP) and elemental (EC1, EC2, and EC3) carbon obtained from IMPROVE (Interagency Monitoring of PROtected Visual Environments) thermal/optical carbon analysis of quartz-fiber filters have been implemented to help distinguish spark-ignition engine exhaust particulate matter (PM) contributions from those of heavy-duty diesel exhaust. The Positive Matrix Factorization (PMF) source factor containing the optical pyrolysis correction (OP) typically includes significant contributions to sulfate and/or nitrate. This factor is associated with aged secondary organic and inorganic species. The U.S. EPA changed the sampling and analytical protocols for its Chemical Speciation Network (CSN) in the 2007–2009 period to provide these well separated individual peaks in the thermogram for aerosol characterization, source apportionment, visibility, and health studies. However, after October 1, 2018, there was a change in the laboratory and instruments used to implement the IMPROVE_A protocol for CSN samples. Although this switch resulted in similar total organic and elemental carbon (OC and EC) values, the protocol changes resulted in large shifts in the OC4, OP, and EC2 fractions, resulting in a swap in the resolved contributions from gasoline and diesel engine exhaust apportionments of PM2.5 mass concentration. It also affected the OP factor contributions. As a result, using the most recent CSN carbon fractions for source apportionments to separate gasoline from diesel vehicles will not result in correct results. The only current recourse is to reanalyze remnants of those samples using the original and temporally consistent IMPROVE_A protocol. |
| format | Article |
| id | doaj-art-d5624102878f42a89b327ecb86f11088 |
| institution | Kabale University |
| issn | 1680-8584 2071-1409 |
| language | English |
| publishDate | 2023-05-01 |
| publisher | Springer |
| record_format | Article |
| series | Aerosol and Air Quality Research |
| spelling | doaj-art-d5624102878f42a89b327ecb86f110882025-02-09T12:22:02ZengSpringerAerosol and Air Quality Research1680-85842071-14092023-05-012361710.4209/aaqr.230041Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network DataPhilip K. Hopke0Yunle Chen1David Q. Rich2John G. Watson3Judith C. Chow4Department of Public Health Sciences, University of RochesterDepartment of Public Health Sciences, University of RochesterDepartment of Public Health Sciences, University of RochesterDivision of Atmospheric Sciences, Desert Research InstituteDivision of Atmospheric Sciences, Desert Research InstituteAbstract The carbon fractions of organic (OC1, OC2, OC3, OC4, OP) and elemental (EC1, EC2, and EC3) carbon obtained from IMPROVE (Interagency Monitoring of PROtected Visual Environments) thermal/optical carbon analysis of quartz-fiber filters have been implemented to help distinguish spark-ignition engine exhaust particulate matter (PM) contributions from those of heavy-duty diesel exhaust. The Positive Matrix Factorization (PMF) source factor containing the optical pyrolysis correction (OP) typically includes significant contributions to sulfate and/or nitrate. This factor is associated with aged secondary organic and inorganic species. The U.S. EPA changed the sampling and analytical protocols for its Chemical Speciation Network (CSN) in the 2007–2009 period to provide these well separated individual peaks in the thermogram for aerosol characterization, source apportionment, visibility, and health studies. However, after October 1, 2018, there was a change in the laboratory and instruments used to implement the IMPROVE_A protocol for CSN samples. Although this switch resulted in similar total organic and elemental carbon (OC and EC) values, the protocol changes resulted in large shifts in the OC4, OP, and EC2 fractions, resulting in a swap in the resolved contributions from gasoline and diesel engine exhaust apportionments of PM2.5 mass concentration. It also affected the OP factor contributions. As a result, using the most recent CSN carbon fractions for source apportionments to separate gasoline from diesel vehicles will not result in correct results. The only current recourse is to reanalyze remnants of those samples using the original and temporally consistent IMPROVE_A protocol.https://doi.org/10.4209/aaqr.230041Carbon fractionsSource apportionmentGas/diesel separationThermal/optical analysisIMPROVE_A protocol |
| spellingShingle | Philip K. Hopke Yunle Chen David Q. Rich John G. Watson Judith C. Chow Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data Aerosol and Air Quality Research Carbon fractions Source apportionment Gas/diesel separation Thermal/optical analysis IMPROVE_A protocol |
| title | Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data |
| title_full | Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data |
| title_fullStr | Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data |
| title_full_unstemmed | Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data |
| title_short | Issues with the Organic and Elemental Carbon Fractions in Recent U.S. Chemical Speciation Network Data |
| title_sort | issues with the organic and elemental carbon fractions in recent u s chemical speciation network data |
| topic | Carbon fractions Source apportionment Gas/diesel separation Thermal/optical analysis IMPROVE_A protocol |
| url | https://doi.org/10.4209/aaqr.230041 |
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