泰来藻、海菖蒲体内铜的化学形态与累积规律

Chemical forms and accumulation patterns of Cu in two sea grass species Thalassia hemprichii and Enhalus acoroides

采用化学逐步提取法,研究了中国2种典型热带海草泰来藻(Thalassia hemprichii)和海菖蒲(Enhalusa coroides)在不同浓度铜胁迫下,其不同部位(根、茎、叶)对铜的累积及其化学形态。结果表明:2种海草中铜的累积模式均表现为叶>根>茎,说明叶是铜最主要的累积部位;2种海草叶中的铜主要以盐酸提取态为主,表明稳定且毒性低的草酸铜是海草叶中铜的主要存在形式;2种海草茎中铜都是以氯化钠提取态为最主要的存在形态,表明海草茎中的铜主要是以活性较高的蛋白质结合形态存在;在泰来藻根部,醋酸提取态为铜主要的存在形态,说明铜主要以毒性较低且较稳定的磷酸盐形式存在,而在海菖蒲根部,铜以多种结合形态存在。此结果可为研究重金属对海草的毒害机理提供依据。

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 hemprichii and Enhalus acoroides under different ambient Cu concentrations. For both T. hemprichii and E. acoroides,the Cu accumulation 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. acoroides root,various Cu forms were found. Our results could provide a basis for studying the toxic mechanisms of heavy metals on sea grasses.