Characteristics of ionic components in precipitation in Kitakyushu City, Japan

Precipitation samples were collected by filtrating bulk sampler in Kitakyushu City, Japan, from January 1988 to December 1990. Volume weighted annual mean of pH was 4.93, but the pH distribution indicated that most probable value lay in the range pH 6.0–6.4. Volume weighted annual mean concentrations of major ionic components were as follows; SO 4 2− : 84.2, NO 3 − : 28.1, Cl−: 86.3, NH 4 + : 45.5, Ca2+: 63.3, Mg2+: 27.0, K+: 3.4, Na+: 69.0 µ eq l−1. The highest concentrations of these ionic components were observed in winter and the lowest occurred in the rainy season. The ratio of ex-SO 4 2− /NO 3 − exhibited the lowest ratio in summer, and the highest ratio in winter. Good correlations were obtained between Cl− and Na+, ex-SO 4 2+ and ex-Ca2+, NO 3 − and ex-Ca2+, and NH 4 + and ex-SO 4 2− , respectively. However, no correlation between Cl− and Na+ with Ca2+ was observed. The relationship of H+ with (ex-SO 4 2− + NO 3 − ) - (ex-Ca2+ + NH 4 + ) indicated positive correlation.