PCDD/Fs and PCBs scavenged through cloud water during northeast monsoon

Area of Science:

• Environmental Chemistry
• Atmospheric Science
• Pollutant Transport

Background:

• Limited research exists on chlorinated persistent organic pollutants (Cl-POPs) in cloud/fog water.
• Cl-POPs include polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs).

Purpose of the Study:

• To investigate the characteristics, partitioning, and scavenging efficiency of Cl-POPs in cloud/fog water.
• To compare Cl-POP scavenging by cloud/fog water versus precipitation.

Main Methods:

• Deployment of active and passive cloud/fog collectors on Mt. Bamboo, Taiwan.
• Collection and analysis of cloud/fog water samples during the 2018-2019 northeast monsoons.
• Quantification of Cl-POPs, differentiating between particle-bound and dissolved phases.

Main Results:

• Cloud/fog water exhibited significantly higher Cl-POP concentrations than precipitation.
• PCDD/Fs were primarily particle-bound (79%), while PCBs were mostly dissolved (>50%).
• Scavenging ratios for PCDD/Fs in cloud/fog water (10^4-10^7) exceeded those in precipitation (10^3-10^5).

Conclusions:

• Cloud/fog water plays a critical role in scavenging atmospheric Cl-POPs.
• The findings suggest potential for long-range transport of these pollutants via cloud/fog.
• Understanding this process is crucial for assessing environmental and human health risks.