Spatial settling process of Pb in Jiaozhou Bay

Abstract

We analyzed the vertical distributions, seasonal variations and transfer processes of Pb in Jiaozhou Bay based on investigation data in surface and bottom waters in 1986. Results showed that Pb contents in surface waters were in order of spring < autumn < summer. By means of vertical water's effect, Pb was settling from surface waters to bottom waters continuously, and was accumulating in bottom waters continuously, resulting in Pb contents in bottom waters were in order of spring < summer < autumn. The variation ranges of Pb contents in April, July and October in waters in the bay mouth were basically consistent. In case of Pb contents in surface waters were low, accumulation effect was making a role in bottom waters. In case of Pb contents in surface waters were high, dilution effect was making a role in bottom waters. The seasonal variations of Pb contents in surface waters were following to the seasonal variation of the inflow rivers, while the seasonal variations of Pb contents in bottom waters were determining by vertical water's accumulation effect. For spatial scale, Pb contents in surface and bottom waters were tending to be consist, no matter the input of Pb was different in time, source and source strength. In generally, the seasonal variations, variation ranges and horizontal distributions of Pb contents in surface and bottom waters were confirming the vertical settling process that Pb was settling to sea bottom rapidly by means of gravity force and marine current.