Variation of rain chemistry during storms at two sites in northern California

Water Resources Research
By: , and 



The chemical composition of rainfall at Menlo Park, on San Francisco Bay, is compared with rainfall at Petrolia, which is near the coast about 500 km north of San Francisco. Sequential samples representing 1.35 to 5.4 mm of rain were collected from November 1971 to January 1972. At rural Petrolia the Cl:Na ratio was that of seawater for Cl concentrations ranging from 0.02 to 38 mg/l. In metropolitan Menlo Park the Cl:Na ratio in rain closely approximated that in seawater above about 0.5 mg/l Cl, but at lower Cl concentrations the ratio exceeded that in seawater, a fact attributed to the presence of anthropogenic Cl. Other constituents dissolved in Menlo Park rain (along with their concentration ranges in milligrams per liter), and believed to be derived in part from anthropogenic sources, were Ca (0.01–1.07), Mg (<0.01–1.08), Pb (0.003–0.035), Zn (0.002–0.013), Mn (0.0001–0.0057), Cu (0.0008–0.0024), NO3‐N (0.02–0.54), and Br (<0.01–0.12). The range of pH values was smaller in the rural than in the metropolitan areas; average H+ activity corresponded to a pH of 5.1 to 5.2 in both areas. At Petrolia, pH decreased with increased dissolved salts in rainfall, but no relation between pH and dissolved salts was evident at Menlo Park.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Variation of rain chemistry during storms at two sites in northern California
Series title Water Resources Research
DOI 10.1029/WR015i003p00687
Volume 15
Issue 3
Year Published 1979
Language English
Publisher American Geophysical Union
Contributing office(s) California Water Science Center
Description 16 p.
First page 687
Last page 702
Country United States
State California