The Dynamic Vertical Variation of Cadmium Content Caused by Source and Transport Volume

Based on investigation data of Cd in Jiaozhou Bay in May and August of 1991, according to horizontal and vertical variation of Cd content, the vertical distribution and sedimentation region was displayed by the difference in Cd content at surface and bottom in bay mouth. The results showed that Cd content in May reached 0.58μg/L from ships and wharfs in northern bay mouth, and 0.40μg/L in August from atmospheric sedimentation in bay center. In spatial variation, with the increasing distance from source, spatial variation of Cd content was presented. In May, compared with bottom, Cd content at surface was higher in northern bay mouth and lower in bay center, which, whereas, was contrary in August. From the perspective of time, the source of Cd content changed along with time, displaying the variation of Cd content at surface and bottom. From May to August, the source varied from ships and wharfs to atmospheric sedimentation with a decreasing Cd content at surface. Thus, the variation in space and time proved the dynamic vertical variation rule of Cd content proposed by the author. In specific, with the farther source, Cd content at surface could rapidly and constantly sediment to seafloor, vertical disputed amount of Cd content at surface and bottom decreased, then varied to vertical sediment amount, which increased from the lowest value.