Y. Ishikawa et al., HIGH SULFATE AND NITRATE CONCENTRATIONS IN PRECIPITATION AT NAGASAKI IMPACTED BY LONG-DISTANT AND LOCAL-SOURCES, Atmospheric environment, 32(17), 1998, pp. 2939-2945
Wet-only event-basis precipitation data at Nagasaki, the border area b
etween the Asian Continent and Japan, with high non-sea-salt (nss-) SO
42- and NO3- concentrations from November 1983 through March 1988 were
analyzed in terms of wind conditions at upper and surface levels to a
ssess both long-distant and local sources. In order to investigate the
high nss-SO42- concentration events occurring with similar transport
patterns, the wind conditions were grouped into the following three ty
pes: type 1, the upper air flow from the Asian Continent and the surfa
ce wind from the sea; type 2, the stagnant upper air and the surface w
ind from the land at and around Nagasaki; and type 3, the upper air fl
ow from the Continent and the surface wind from the land. In the case
of high MO; concentration events, their wind-condition types were simi
lar to those for high nss-SO42- concentration events. These three type
s for both ions were discussed to estimate their sources as follows: t
ype 1, long-distant sources in the Asian Continent; type 2, local sour
ces at and around Nagasaki; and type 3, both long-distant and local so
urces. From the viewpoint of precipitation chemistry, the ratios of H / (nss-SO42- + NO3-) were evaluated for the high concentration events
so as to examine the degree of neutralization of acidic input, H2SO4
and HNO3. High ratios events corresponded to wind-condition type 2 whe
reas low ratios were associated with types 1. This suggested that the
acidic input from local sources were little neutralized to cause much
higher acidity in precipitation than those from long-distant sources.
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