Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 1985 | Published
Journal Article Open

Chemical characterization of stratus cloudwater and its role as a vector for pollutant deposition in a Los Angeles pine forest


Highly concentrated, acidic stratus cloudwater was monitored as it intercepted a pine forest (Henninger Flats) 25 km northeast of Los Angeles. Observed pH values ranged from 2.06 to 3.87 for over 100 samples collected in 1982 and 1983 with a median value below pH 3. The ratio of nitrate/sulfate in cloudwater samples was between 1.5 and 2: rainwater at the same site had a ratio of approximately 1. The solute deposition accompanying several light. spring rains (summing to ~1 % of annual rainfall) was a disproportionate fraction of the annual total: H^+. NO_3 and SO _4^2 were -20% or more. Based on a reasonable estimate of fog precipitation, deposition of sulfate, nitrate and free acidity due to intercepting stratus clouds may be of comparable magnitude as that due to the incident rainfall at Henninger Flats. Cloudwater that had deposited on local pine needles was collected. It was in general more concentrated than ambient cloudwater but with comparable acidity. Enrichment of K^+ and Ca^(2+) in those samples and in throughfall is believed to be due to leaching from foliar surfaces. Injury to sensitive plant tissue has been noted in the literature when prolonged exposure to this severe kind of micro-environment has been imposed.

Additional Information

This journal is published under the terms of the Creative Commons Attribution 4.0 International (CC-BY 4.0) License. Manuscript received June 25; in final form December 4. 1984. We are grateful to the Los Angeles Fire Department Forestry Bureau for allowing us to conduct our field monitoring at Henninger Flats and to the Rangers at the site for their assistance. This research has been supported by a contract with the California Air Resources Board (Contract No. A2-048-32), with additional support from the Coordinating Research Council.

Attached Files

Published - j.1600-0889.1985.tb00058.x.pdf


Files (1.3 MB)
Name Size Download all
1.3 MB Preview Download

Additional details

August 19, 2023
October 23, 2023