Distribution and Enrichment of Heavy Metals in the Mangrove Plants of Aegiceras Corniculatum and Kandelia Candel Collected from Luoyang Estuary in Quanzhou Bay

The distribution, enrichment and migration characteristics of heavy metals in the mangroves of Aegiceras corniculatum and Kandelia candel were studied by means of determining the contents of acid extractable heavy metals in surface sediments and in different parts of each mangrove collected from the mangrove swamp in Luoyang estuary of Quanzhou Bay. The main sources of heavy metals in the investigated mangroves were also discussed preliminarily in this article. The contents of heavy metals in the surface sediments showed a sequence of Fe>Mn>Zn>Pb>Cu>Cr>Ni>Co, in which the average contents of Cu and Pb were higher than the quality standard limit (level Ⅰ) for marine sediments. The contents of heavy metals in different parts of both mangroves were in the accordant order of root>branch>leaf for Cu, leaf>root>branch for Ni and root>leaf>branch for Fe, Mn, Cr, Zn, Pb and Co. The enrichment capability for Ni, Cr, Cu, Zn, Fe and Mn in both mangroves was higher than that for Co and Pb. The enrichment capacity of Kandelia candel for Cu, Ni, Mn, Fe and Co was higher than that of Aegiceras corniculatum, while relatively lower for Zn, Cr and Pb. But the two kinds of the plants can not come up to the requirements of hyper-accumulators according to their accumulation capacity for each element. For both plants, the enrichment capability for Ni was the highest, which concentrated mainly in leaves. While the other elements mainly concentrated in roots. Except for Ni, the migration factors of all other elements in both plants were lower than 1. The content of Cr in Aegiceras corniculatum and Cu, Zn and Mn in Kandelia candel were mainly derived from the mangrove sediments, and there were different sources for other elements that accumulated in different parts of two plants.