太湖南泉水域水体及水华蓝藻中常量元素Ca Na Mg K和Al的特征和变化

Characteristics and Variation of Major Element Ca,Na,Mg,K,Al in Waters and Water-bloom-forming Cyanobacteria in Nanquan Area of the Taihu Lake,China

近年来以微囊藻为优势种的太湖蓝藻水华持续暴发,已经成为严重的环境问题之一。本文通过现场采样及室内分析,研究了2009年太湖南泉水域蓝藻发生过程中藻类群落组成的变化,并同步研究了蓝藻体内及其水环境中常量元素Ca、Na、Mg、K和Al元素浓度的周年变化,分析了三者之间可能的相关性。研究显示,太湖蓝藻发生时间为6—10月,期间水温保持在20℃以上,pH值在水华发生后期可升高至9.8;水体中元素浓度依次为Na>Ca>Mg>K>Al,而水华蓝藻中元素浓度依次为Ca>K>Mg>Na>Al;藻体对水体环境中元素的富集系数大小依次为Al>K>Mg>Ca>Na。研究结果既为选择最佳物理除藻时期来有效降低湖泊中常量元素的负荷量,从而进行水华控制提供了支撑,也为今后将富含元素的水华蓝藻作为"生物矿源"加以利用提供了理论依据。

The Taihu Lake is the third largest freshwater lake in China.Recently,heavy cyanobacterial blooms,being dominated by microcystis,have broken out frequently in this lake every year,and therefore,become a serious environmental problem.In the present work,a year-round study was conducted to investigate the variations of the community composition of waterbloom-forming cyanobacteria,the concentrations of major element Ca,Na,Mg,K,Al in the cyanobacteria and ambient water,and the changes in water temperature and pH at Nanquan area of the Taihu Lake from March 2008 to February 2009.Results showed that the most intense waterbloom happened from May to October during the study period with the water temperature maintained above 20 ℃ and the pH increased distinctly in October.The concentrations of the major elements in water samples were follow the order NaCaMgKAl,and those in cyanobacterial samples were CaKMgNaAl.The calculated bioaccumulation factors of cyanobacteria were in the following order AlKMgCaNa.The concentration of Na in the cyanobacterial samples was even lower than that in water samples.In addition,the highest bioaccumulation factor was documented for Al in water-bloom cyanobacteria,which was as high as 19 194 in July.The results of the present study could serve as fundamental insights for further investigation on the functional significance of these element to the occurrence and development of cyanobacterial water blooms,and furthermore,provided important evidence for the potential apporach of water-bloom control by removing major element burden.This study also suggested that water-bloom-forming cyanobacteria could be used as an important ＂bio-mine＂ resource,due to its huge amount of biomass and extreme accumulation of these major elements.