Evaluation of sea-salt origin pollutants in precipitation at Akita using constrained oblique rotational factor analysis

Abstract

The validity of the classification of sea-salt and non-sea-salt origins of pollutants in precipitation was evaluated using a constrained oblique rotational factor analysis. The precipitations used for this analysis were collected from April, 1993 to March, 1995 in Akita and from January to March of 1994 and 1995 in Yuzawa on a day-after-day basis. The chemical compositions in these precipitations were analyzed and their four sub-data-sets (a two-year data-set of Akita, a data-set of winter season in Akita, a data-set of seasons except for winter in Akita and a data-set of winter season in Yuzawa) were analyzed using the factor analysis. Three or four pollutant sources were quantitatively extracted for each data-set. The factor analysis has extracted a factor ascribed to the sea-salt (ss) component without using any information concerning its composition. However, a part of the sodium and chloride ion is also involved in another acidic factor, which contains sulfuric acid. This means that part of sea-salt particles suffered a chemical reaction while coming to the precipitation place from the Sea of Japan.