关键词: 城镇化, 城镇扩展强度指数, 景观格局指数, 北京昌平区

Abstract: Sediment and water samples were collected from Jinzhou Bay and three rivers of Huludao to investigate their arsenic concentration, distribution, and forms. The arsenic concentration in the sediments and waters of Lianshan River and Wuli River, and in the sediments of the downstream of Cishan River adjacent to zinc refining plant was lower than 10 mg·kg-1 and 10 μg·L-1, and reached to 752 mg·kg-1, respectively, indicating that the former two rivers did not suffer significant arsenic pollution, while the downstream of Cishan River was arsenic-polluted to a certain degree. Wuli Estuary was very seriously arsenic-polluted. In the effluent of zinc refining plant at Wuli Estuary, the arsenic concentration was as high as 31761 mg·kg-1, being 158 times higher than the national sediment guideline. Because of the release of effluent and slag from the zinc refining plant, Jinzhou Bay was also very seriously polluted, with the highest concentration of arsenic reached to 5695 mg·kg-1. There was a similar vertical distribution pattern of arsenic concentration in the sediments and pore-water, suggesting that the arsenic concentration in pore-water was mainly controlled by that in sediments. The results of sequential extraction showed that exchangeable arsenic was the dominant form, followed by residual arsenic, and amorphous Fe oxides-arsenic, illustrating that the arsenic in the sediments was very active and easily released to the above waters, possessing a chronic and serious threat on the ecosystems of Huludao and Jinzhou Bay. The influence of Fe oxides on the behaviors of arsenic in the sediments was not significant.

Key words: Urbanization, Urbanization expanding index, Landscape metrics, Changping District