Spatial-temporal variations of Cd in Jiaozhou Bay

Abstract

We analyzed the horizontal, vertical and seasonal variations of Cd in waters in the bay mouth of Jiaozhou Bay, eastern China in 1984. Results showed that, for seasonal variation Cd contents in waters were higher in autumn than in summer, which were determined by the equatorial Kuroshio flowing. For horizontal variation, Cd contents in surface waters in summer were decreasing from the outside of the bay mouth to the bay mouth, and then to the inside of the bay mouth, yet there was no trend in autumn. However, Cd contents in both surface and bottom waters in summer and autumn were both decreasing from the outside of the bay mouth to the bay mouth, and then to the inside of the bay mouth. For vertical variation, the differences of Cd contents in surface and between which in bottom waters were little no matter Cd contents were high or low, due to the rapidly and continuously sedimentation of Cd. For regional variation, a little amount of Cd was inputted by marine current, leading to the higher Cd contents in surface waters than in bottom waters. Both the temporal and spatial variations of Cd contents in waters were revealing the horizontal water’s effect and vertical water’s effect, as well as the horizontal transfer process and horizontal sedimentation process.