Horizontal Distribution Trend of Cadmium Content in Surface and Bottom Waters

Abstract

According to investigation data of Jiaozhou Bay in 1991, this paper studied the vertical distribution and seasonal variation of Cd in surface and bottom waters from bay center to northern bay mouth, and determined its seasonal distribution, variation range and horizontal distribution trend. The results showed that in May and August, in the entire waters from bay center to northern bay mouth, from surface to bottom, the Cd content range was 0.06-0.58μg/L, which shows that the water was not polluted by Cd. From May to August, in bay center, the seasonal variation of Cd content at surface and bottom was an order of summer > spring. In May and August, in northern bay mouth, the seasonal variation of Cd content at surface was an order of spring > summer, and summer > spring at bottom. The seasonal variation of Cd content shows that the Cd content at surface was not controlled by season, but source transport. Besides, Cd content at bottom was not controlled by season, but cumulative effect and dilutive effect when Cd content at surface reached seafloor. In Jiaozhou Bay, in surface and bottom waters from bay center to northern bay mouth, the horizontal distribution trend of Cd contents at surface and bottom was presented. The horizontal distribution trend of Cd content at surface and bottom was opposite in May and consistent in August. The results disclosed the principle of horizontal distribution trend at surface and bottom. Cd content was transported from sources reached surface, then rapidly and constantly sedimentated to seafloor. When Cd content reached high before being cumulated in seafloor, the horizontal distribution trend of Cd content at surface and bottom was consistent. On the contrary, it was opposite. In bottom waters, the accumulation of Cd content and its gravity features determined the consistent horizontal distribution trend of matter content at surface and bottom.