Concentrations of some ionic species in Central Long Island, New York precipitation in relation to meteorological variables

Abstract

Three years of hourly sequential precipitation data from central Long Island, New York were analyzed to determine the concentrations of major anions and cations and their relationships to each other and to meteorological conditions. Findings with respect to sulfate, nitrogen in nitrate plus nitrite, nitrogen in ammonium, chloride and sodium ions and selected ratios are reported here. Concentrations of each of the first three species were highly correlated with concentrations of the others and with hydrogen ions. Little correlation was found between these species and either sodium or chloride ions but the latter two were highly correlated with each other. Concentrations of the first three species are highest in summer and lowest in winter. High concentrations were also found with cold front and squall line precipitation and with rain showers and thundershowers. Concentrations of these species are high with both low and high precipitation rates. Concentrations are highest with west and northwest winds due to the presence of major source regions in those directions. They are high with both low and high temperatures but lower in the moderate temperature range. Concentrations are high with low (3.0 to 3.9) and with high (6.0 to 6.9) pH but less at intermediate levels. Thus, concentrations of these species in precipitation are determined by complex chemical and meteorological interactions and relationships. Chloride and sodium were found to be largely of marine origin. Highest concentrations occur in the fall and with hurricanes, strong winds, and onshore wind directions. Concentrations decrease with increasing precipitation rate. At low concentrations, the chloride/sodium ratio is above the seawater ratio and excess chloride is present. At high concentrations the ratio is below the seawater ratio and a chloride deficit exists.