Evaluation of Ionic Pollutants of Acid Fog and Rain Using a Factor Analysis and Back Trajectories

Abstract

Recently, acid precipitation is receiving global interest because it affects terrestrial and aquatic ecosystems. 1,2 Our research group has studied 3-7 the acid precipitation of Hyogo and Akita prefectures in Japan, combining a chemical analysis of the ionic substances with meteorological situations, and has analyzed pollutants by a factor analysis. [3][4][5][6][7] Furthermore, investigations for the fog on a mountain ridge showed by a factor analysis that a fog droplet had some soluble pollutants (e.g. (NH4)2SO4, seasalt, H2SO4 and HNO3), and that the uptake mechanism by a fog droplet would be different for each pollutant.It is well-known that fog/cloud water is more acidic and has a higher concentration of pollutants than rain water. 5,9-11 Nevertheless, prior attempts 15,16 to elucidate the mechanisms of fog acidification, especially the behavior of the ionic substances in the fog droplets, have not been quantitatively conclusive. There has been no investigation, moreover, concerning where the air pollutants specified by employing the oblique rotational factor analysis 3,4,6,12 are transferred.Our purpose here was threefold. First, by using an oblique rotational factor analysis, we examined the observed drop size dependence of the chemical composition during fog events at Akita Hachimantai mountain range from June to September of 1998 and 1999. Second, we evaluated the transport of some air pollutants in combination with ionic substances which were quantitatively extracted from a factor analysis developed by our research group, 3,4 with a 72 h back trajectory at the 850 hPa level and from the point of view of a synoptic weather system. Third, from the feature of chemical composition of fog or rain, which was non-ion-balanced, we tried to estimate unknown soluble chemical species. ExperimentalFog water was collected on a mountainside (39˚56′N, 140˚51′E, 1465 m, a.s.l.) of Mt. Mokkodake (1578 m, a.s.l.) in the Akita Hachimantai mountain range from June to September of 1998 and 1999 (Fig. 1) Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.

Increase of Pollutants in Radiation Fog by Fumigation at Takanosu Basin in Northern Japan

“…Using the series sampling by constant volume of the radiation fog, it was clarified that the increase in pollutant of air by fumigation results in the increase of pollutant in fog droplets. ) concentrations, pH and electric conductivity of the fog water collected and the analysis of the mean volume diameter of the fog droplets, as well as the estimation method of the transport course of air mass have been reported elsewhere [9]. Liquid water content (LWC) was measured using a liquid water content meter (EPS-001; Usui Kogyo Kenkyusho Inc.).…”

“…. In generally, as the droplet size decreases, the ion concentration (μeq/L) becomes higher and as the droplet size increases, the concentration decreases according to a water-diluting effect [9,10]. Therefore, if the ion concentration (μeq/L) was used, it cannot be decided whether the increase in the ion concentration of the fog is due to the effect of the droplet size or fumigation.…”

Effect of Long-range Transport of Air Mass on the Ionic Components in Radiation Fog in Northern Japan

“…Our research group has studied acid fog and precipitation in the Akita Hachimantai mountain range of northern Japan, by combining chemical analysis with 72-h back trajectories. [1][2][3] Adzuhata et al found that the acidity of fog water was very high when an air mass was transported from northeastern China to the Hachimantai range. 3 It is widely known that upslope fog in a mountain range is directly influenced not only by short-range transport, but also by the long-range transport of ionic pollutants.…”

“…[1][2][3] Adzuhata et al found that the acidity of fog water was very high when an air mass was transported from northeastern China to the Hachimantai range. 3 It is widely known that upslope fog in a mountain range is directly influenced not only by short-range transport, but also by the long-range transport of ionic pollutants. There are some reports on the effect of long-range transport of pollutants to a basin, [4][5][6] and the pollution mechanism of radiation fog.…”

Spectrofluorometric Resolution of Closely Overlapping Drug Mixtures Using Chemometrics Methods

“…All of these methods are based on improving the selectivity of the coexisting components. Chemometric methods, such as factor analysis, [6][7][8][9][10] have become even more popular in solving problems that are difficult to handle using conventional techniques, without having to resort to expensive or time-consuming procedures. Especially, three-way resolution and calibration methods [11][12][13] play important roles in solving the problem of closely overlapping fluorescence spectra.…”