关键词: 芦苇, UV-B辐射, 光合特性, 光合色素, 叶绿体超微结构

Abstract: The concentration, distribution, and speciation of heavy metals in urban soils of Haikou City were investigated. The mean concentrations of heavy metals Hg, As, Cd, Cu, Cr, Ni, Pb and Zn were 0.073, 3.82, 0.25, 26.7, 92.4, 52.5, 29.1 and 84.1 mg·kg^-1, respectively. In comparison with the background values, the enrichments of Hg, As, Cd, Cu, Cr, Ni, Pb and Zn in the soils of Haikou City were obvious, indicating a certain degree of heavy metal pollution. Cr, Ni, Cu, Cd and Zn were enriched in suburban areas, while Pb was enriched in roadside green belts and Hg was enriched in residential areas. Zn, As, Cr, Cu and Ni in the soils of Haikou were predominantly in residual fraction. Hg was mainly associated with strong organic-bound and residual fractions, while Pb was mainly presented as iron and/or manganese oxide-bound fractions. On the contrary, Cd existed mainly in bio-available fractions. The results of multiple-metals ecological risk assessment indicate that the heavy metal pollution in the soils of Haikou is at a relatively low level. However, Cd and Hg pollution deserves much more attention.

Key words: Phragmites australis, UV-B radiation, photosynthetic characteristics, photosynthetic pigment, chloroplast ultrastructure.