Chemistry of Rainwater and Cloud Water at Remote Sites in Alaska and Oregon

Cloud water and rainwater were examined at remote sites in southeastern Alaska and coastal Oregon using standardized collection and analytical techniques. Cloud water and rainwater were characterized by extremely low concentrations of most ions except SO 2− 4 , Na + , and Cl − . Acidity was greater than expected because of organic acids from unknown sources. Concentrations of NO − 3 and NH + 4 were extremely low, especially compared to samples collected similarly in the eastern USA. Rainwater did not differ between Alaska and Oregon except in concentrations of Ca 2+ , Mg 2+ , K + , Na + , and Cl − . Cloud water generally had higher concentrations of ions than rainwater, especially in NO − 3 , NH + 4 , and SO 2− 4 . Ion concentrations were highly variable and non‐normally distributed. Sample sizes in future studies should be large (>40). Cloud water deposition may be very important in terms of potential pollution effects and nutrient cycling in ecosystems with frequent cloud cover.