The Relationship of Concentrations of the Major Ion in Rain and Snow Deposition to Meteorological Factors

A Statistical Analysis by Using the Quantification Method of First Type for Non-Seasalt Sulfate Ion

Abstract

The multivariate analysis was applied for our better understanding of the relationship between meteorological factors and the major ion concentrations in rain and snow depositions. The analyzed wet deposition was collected on each event basis at two sampling stations placed in Muroran and Morino, southwest Hokkaido from July, 1990 through December, 1992. Because one of the most serious pollutant species has been hitting our environment, the variation in content of non-seasalt (nss) SO₄^2- ion in wet depositions was investigated by the quantification method of first type with respect to meteorological factors. It is found that the analyzed meteorological factors contribute to the concentration of nssSO₄^2- in the following ascending order: season, wind direction, back trajectory course and the amount of deposition. The analysis for back trajectory course by this particular method also revealed that a portion of nssSO₄^2- contents orginated from industrial pollutant emissions from geographical sources, viz in southeast China and east Russia. It is suggested that the wind direction can be utilized as an indicator to identify local sources of pollutant species in wet precipitation. Thus, the employment of multivariate analysis is more effective than a simple mathematical analysis in order to see the exact relationship between the conentration of a given ionic species in wet deposition and the meteorological factors.