Chemistry of precipitation from a remote, terrestrial site in Australia

Wet‐only rain samples were collected and chemically analyzed during 1980–1984 at Katherine, Australia, as part of the Global Precipitation Chemistry Project. Rainfall averaged 104 cm/yr and ranged from 74.6 cm in 1982–1983 to 135.7 cm in 1983–1984. Total cation concentration was about 29 μeq/L. The volume‐weighted mean H+ concentration expressed as pH was 4.73, 64% of the free acidity was due to organic acids (formic and acetic). The pH due to strong mineral acids only was 5.08. Air mass trajectories during the wet season were predominantly from the northeast (51%), and this trajectory was most important in terms of deposition. Although there is a high frequency of lightning during the wet season, no evidence was found that it contributed significantly to the nitrate concentration in rain. Because concentrations decreased markedly with amount of precipitation, the total deposition of dissolved substances was not correlated directly with the amount of rain. Comparisons were made between the chemistry of rain at Katherine and with other remote areas and with the eastern United States.