Temporal variation of trace element concentrations in selected rainfall events at Tsukuba,Japan

Using ICP emission spectrometry, the temporal variation of the concentration of dissolved Al, Fe. Si, Mn, Zn. Cu and B in rain-water during an event was observed at Tsukuba, Japan. The relationships between trace element variations and rainfall characteristics were compared with those for major elements such as Na, K, Ca and Mg. In many cases, the concentration of minor elements was highest in the initial stage. The exception was in rain with very short duration or very strong intensity at the initial stage of rainfall.No significant relationship was observed between rainfall intensity and soluble elemental concentration, although in a few cases AI, Zn, Na and Fe showed an inverse correlation with rainfall intensity. It was found that the concentration of minor elements such as Fe, Al and Zn fluctuated, whereas those of Na and other major elements changed smoothly. This difference is considered to be caused by differences in the scavenging process of the elements as well as the heterogeneous and varying distribution of atmospheric particles which supply minor elements in rain-water.