7Be, 210Pb and 137Cs concentrations in cloud water.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Radiochemistry

Background:

• Cloud water composition is vital for understanding atmospheric deposition.
• Radionuclide monitoring is essential for assessing environmental contamination, particularly post-nuclear events.

Purpose of the Study:

• To determine the concentrations of beryllium-7 (7Be), lead-210 (210Pb), and cesium-137 (137Cs) in cloud water.
• To establish a reference level for 137Cs in cloud water, representing long-term post-accidental background.
• To compare radionuclide deposition in cloud water versus rainwater and assess aerosol scavenging efficiencies.

Main Methods:

• Cloud water sampling over 8 months (2008-2009) at a high-altitude atmospheric research station.
• Measurement of activity concentrations for 7Be, 210Pb, and 137Cs using established radiometric techniques.
• Calculation of cloud-to-rain concentration ratios and aerosol scavenging efficiencies.

Main Results:

• Average activity concentrations: 7Be (1.9±0.11 mBq m⁻³ air), 210Pb (140±10 μBq m⁻³ air), and 137Cs (0.14±0.02 μBq m⁻³ air).
• The measured 137Cs level indicates a long-term post-Chernobyl accident background.
• Cloud-to-rain concentration ratios ranged from 3.4 to 8.1, while aerosol scavenging efficiencies were low (0.13-0.40).

Conclusions:

• This study provides the first reference data for 137Cs in cloud water.
• Cloud water radionuclide concentrations are significant for assessing wet deposition, especially in high-altitude regions and during fog events.
• Lower scavenging efficiencies for aerosols by cloud droplets were observed compared to soluble inorganic ions.