Sodium/Potassium Ratio in Rain-water

Abstract

DR. B. C. V. ODDIE has commented1 on a portion of my recent article “Surface of the Ocean as a Source of Air-Borne Nitrogenous Material and Other Plant Nutrients”2 with particular reference to the sodium/potassium ratio in rain-water. In this article I presented results of the analysis of New Zealand snows and proposed that there exists on the surface of the ocean a very thin layer which is rich in potassium, nitrogenous material and other substances as a result of the activities of micro-organisms. It was suggested that portions of this layer are transferred to the atmosphere by the bursting of bubbles in ‘white caps’ and thence to the land. I referred to the fact that the sodium/potassium ratio in rain is often markedly lower than that in bulk sea-water and suggested that the excess potassium was coming from the surface layer described above. Oddie directs attention to the fact that the low sodium/potassium ratios commonly recorded at inland collecting stations are scarcely ever observed at exposed coastal stations in Europe and North America and states that in general the more maritime the situation of a station the more closely does the ratio approximate to that of sea-water (that is, 27). He makes reference to results from the Shetland Islands. Oddie further states, however, that this is evidence against my suggestion, at least for European and American rains.