Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China.

Toxics

Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.

Published: February 2024

AI Article Synopsis

  • Aerosol liquid water content (ALWC) plays a significant role in the properties and toxicity of aerosols but is rarely measured due to expensive and complex instruments.
  • In a summer 2023 study in Nanjing, researchers utilized a cost-effective method combining a PM monitor and turbidimeters to measure ALWC, revealing it made up about one-sixth of total PM mass.
  • The study found that while ALWC is influenced by relative humidity and PM concentrations, it does not always correlate with air quality index levels, highlighting the need to consider ALWC for accurate assessments of air quality and health impacts.

Article Abstract

Aerosol liquid water content (ALWC) affects the mass loading, optical properties, and toxicity of aerosols. However, the measurement of ALWC is very rare due to its requirement of sophisticated instruments and its high operational costs. In this work, we improved on our previous simple, low-cost method by using a combination of one real-time fine particulate matter (PM) monitor and two turbidimeters and successfully applied these for the direct measurement of ALWC in PM in Nanjing during the summer of 2023. The average ALWC during this measurement period occupied ~1/6 of the total PM mass, and this contribution was even greater with the elevation in the PM concentration. The ALWC was, as anticipated, closely related to the relative humidity (RH) and PM concentrations, but it did not always increase with the air quality index (AQI) due to the fact that polluted periods in summer were often governed by high O levels, not PM levels. The ALWC also had a great impact on visibility; it could decrease the visibility rapidly to hazy conditions when the dry PM was not high (~30 μg m) or the AQI was "good" (75~100), indicating that the air quality classified as "good" using the dry PM concentration might actually be "lightly polluted" if the ALWC is included. We also found that the air mass originating from Northeast China had the lowest PM mass concentration yet the highest ALWC values due to its high RH. Moreover, the quantification of ALWC levels can help us understand the solubility/bioavailability and thus the toxic effects of some specific components (for example, heavy metals or organics). Moreover, the influence of ALWC on air quality classifications should also be considered in the assessment of the health effects of air pollution and in public health early warning and protection.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10974118PMC
http://dx.doi.org/10.3390/toxics12030164DOI Listing

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