Preprints
https://doi.org/10.5194/acp-2021-991
https://doi.org/10.5194/acp-2021-991
 
07 Mar 2022
07 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Measurement Report: An Exploratory Study of Fluorescence and CCN Activity of Urban Aerosols in San Juan, Puerto Rico

Bighnaraj Sarangi1, Darrel Baumgardner2, Benjamin Bolaños-Rosero3, and Olga L. Mayol-Bracero1,a Bighnaraj Sarangi et al.
  • 1Department of Environmental Sciences, University of Puerto Rico - Río Piedras Campus, San Juan, Puerto Rico, USA
  • 2Droplet Measurement Technologies LLC, Longmont, Colorado, USA
  • 3Department of Microbiology, School of Medicine, University of Puerto Rico - Medical Sciences Campus, San Juan, Puerto Rico, USA
  • anow at: Environment and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York, USA

Abstract. Many types of atmospheric aerosols cloud condensation nuclei (CCN) capable of activating as cloud droplets. Some primary biological aerosol particles (PBAP), such as plant spores, pollen, or bacteria, have been identified as such CCN. Urban environments are a source of these bioaerosols, those that are naturally produced by the local flora, or are transported from surrounding regions, and others that are a result of human activities. In the latter case, open sewage, uncovered garbage, mold or other products of such activities can be a source of PBAPs. There have been relatively few studies, especially in the tropics, where PBAPs and CCN have been simultaneously studied to establish a causal link between the two. The metropolis of San Juan, Puerto Rico is one such urban area with a population of 2,448,000 (as of 2020). To better understand the fluorescent characteristics and cloud forming efficiency of aerosols in this region, measurements with a Wideband Integrated Bioaerosol Spectrometer (WIBS), a condensing nuclei (CN) counter, and a CCN spectrometer were made at the University of Puerto Rico – Rio Piedras Campus. Results show that the CCN / CN activation ratio and the fraction of fluorescing aerosol particles (FAP) have repetitive daily trends when the FAP fraction is positively correlated with relative humidity and negatively correlated with wind speed, consistent with previous studies of fungi spores collected on substrates.

The results from this pilot study highlight the capabilities of ultraviolet-induced fluorescence (UV-IF) measurements for characterizing the properties of FAP as they relate to daily evolution of PBAPs. The use of multiple excitation and emission wavelengths, along with shape detection, allows the differentiation of different PBAP types. These measurements, evaluated with respect to previous, substrate-based analysis of the local fungal and pollen spores, have established a starting database of measurements that future, longer term studies will build upon.

Bighnaraj Sarangi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-991', Anonymous Referee #2, 23 Mar 2022
  • RC2: 'Comment on acp-2021-991', Anonymous Referee #1, 01 Apr 2022

Bighnaraj Sarangi et al.

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Dataset to: Measurement Report: An Exploratory Study of Fluorescence and CCN Activity of Urban Aerosols in San Juan, Puerto Rico Bighnaraj Sarangi, Darrel Baumgardner , Benjamin Bolanos Rosero , Olga L. Mayol-Bracero https://doi.org/10.17632/t26dctfk7t.1

Bighnaraj Sarangi et al.

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Short summary
This paper discusses the fluorescent characteristics and cloud forming efficiency of aerosols in an urban site in Puerto Rico. The results from this pilot study highlight the capabilities of ultraviolet-induced fluorescence (UV-IF) measurements for characterizing the properties of FAP as they relate to daily evolution of primary biological aerosol particles (PBAPs). These measurements have established a starting database of measurements on which future, longer term studies will be initiated.
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