Sodium, Potassium, Calcium and Magnesium Content of Northwest Arkansas Rain Water in 1973

Abstract

Individual rains falling on Fayetteville, Ark., in 1973 were analyzed for sodium, potassium, calcium and magnesium. Compared to a drier year, 1955?56, the average concentrations of these elements were lower in 1973 but the fluxes higher, except calcium. Each element had a peak flux in the spring and fall, corresponding to the peaks in the amount of rainfall. Calcium concentration relative to the other elements was uniquely high during late winter and early fall suggesting more wind dependence for calcium. The elemental ratios are near those for crustal rocks not seawater. The monthly fluxes of sodium, potassium and magnesium were nearly constant with increasing rainfall up to six inches of rainfall per month then increased more steeply. Calcium monthly flux increased linearly with increasing rainfall. Extrapolation of the monthly flux to zero rainfall gives a measure of the dry fallout contributed to the fluxes obtained here with open collectors. Dry fallout and wet fallout (rain) are about equal.