Abstract: By the method of sequential extraction, this paper studied the Cu accumulation and its chemical forms in different parts of two tropical sea grass species Thalassia hemprichiiand Enhalus acoroidesunder different ambient Cu concentrations. For both T. hemprichii and E. acoroides, the Cuaccumulation was in the order of leaf > root > rhizome, suggesting that Cu was mainly accumulated in the leaves of the two sea grass species. HCl-extractable Cu was the predominant Cu form in leaf, indicating that the Cu in sea grass leaves was stably fixed and occurred as low toxicity copper complexes. On the other hand, NaCl-extractable Cu was the main Cu form in rhizome, suggesting that the Cu in rhizome was combined with protein and formed as relatively high activity copper complexes. In T. hemprichii root, acetic acid-extractable Cu was the main Cu form, suggesting that the Cu was mostly existed as insoluble copper phosphate, but in E. acoroidesroot, various Cu forms were found. Our results could provide a basis for studying the toxic mechanisms of heavy metals on sea grasses.

Key words: Pinits yunnanenensis, Leptagraphium yunnanense, Tomicus piniperda, Temperature, Resistance