The Consistency of the Cd Content in Lands and Oceans

Based on the data from May, August, and October 1992, the Cd content in the Jiaozhou Bay waters varied from 0.11 to 1.53μg/L, up to the water quality standards of Class I and II seawater. This indicates that the water quality of the entire bay was slightly or not polluted by Cd during this period. In May, the variation of the Cd content in the bay ranged from 0.23 to1.53μg/L, more specifically, the Cd content reached a relatively high level of 1.00-1.53μg/L in the offshore waters near the estuary of Dagu River, Loushan River, Licun River and Haibo River and offshore waters of the north of the bay, leading to a mild contamination, while other waters in the bay were not polluted by the Cd content at all. In August, the variation of Cd content in the bay ranged from 0.11 to 1.11μg/L, more specifically, the Cd content hit the record high of 1.11μg/L in the offshore waters near the estuary of Dagu River and in the waters of the south of the bay mouth, making the waters polluted slightly, while other waters in the bay were not polluted by the Cd content at all. In October, the variation of the Cd content in the bay ranged from 0.12 to 1.11μg/L, more specifically, the Cd content reached a relatively high level of 1.04-1.11μg/L in the offshore waters near the estuary of Loushan River and Licun River, leading to mild contamination, while other waters in the bay were not polluted by the Cd content at all. There are three sources of the Cd content in the Jiaozhou Bay waters: rivers, main sea currents and surface runoff. In other words, these are three ways to transport the Cd content. In these ways, 0.96-1.53μg/L, 1.11μg/L and 1.10μg/L of Cd content are transported respectively. In this regard, the order from the largest to smallest of Cd content delivery is as follows: rivers, main sea currents and surface runoff. The Cd content transported by surface runoff is very close to that transported by main sea currents, indicating that the Cd content emitted by humans to land is consistent with that released to the oceans. Besides, the Cd content transported by the three sources is higher than or close to 1.00μg/L, suggesting that both lands and oceans are mildly polluted by the Cd content.