活体微藻对镉（Ⅱ）的富集机理

选取小球衣藻（Chlamydomonas microsphaera）、铜绿微囊藻（Microcystis aeruginosa）、钝顶螺旋藻（Spirulina platensis）和四尾栅藻（Scenedesmus quadricauda）等4种微藻，通过室内模拟实验，对水体中的Cd2+进行吸附，并对吸附Cd2+的微藻分别采用去离子水、0.2 mol·L-1 CaCl2与研磨处理，测定Cd2+的解脱量，研究活体微藻对重金属离子的富集特征与机理。结果表明：4种活体微藻均对水体中Cd2+有较强的富集能力，在Cd2+初始浓度为10 mg·L-1、溶液pH为7.0的实验条件下，小球衣藻富集量可达76.34 mg·g-1，铜绿微囊藻、钝顶螺旋藻和四尾栅藻富集量分别为24.78、15.28 和 9.85 mg·g-1，说明微藻是良好的重金属吸附剂；4种活体微藻对Cd2+的富集特征均符合准二级动力学方程（R2>0.99），反映出活体微藻对Cd2+的富集主要是一种化学行为；活体微藻对Cd2+的富集主要是离子交换形式的化学吸附，富集比例均在60%以上，其中小球衣藻最高，达86.51%。除化学吸附外，还包括物理吸附与生物吸收，生物吸收所占富集比例为6.75%~18.96%，而物理吸附量最少，为3.02%~14.63%。

Accumulation mechanism of Cd2+ upon living microalgae

Four microalgae including Chlamydomonas microsphaera, Microcystis aeruginosa, Spirulina platensis, Scenedesmus quadricauda and Cd2+ were selected as experiment materials. After studying the accumulation characteristic and mechanism of heavy metal upon living microalgae by simulation experiments as adsorption of Cd2+ upon living algae and desorption with deionized water, 0.2 mol·L-1 of calcium chloride and grinding respectively. Result showed that all four microalgae could accumulate strongly Cd2+ in water, and the accumulation of Cd2+ upon Chlamydomonas microsphaera was 76.34 mg·g-1, Microcystis aeruginosa, Spirulina platensis and Scenedesmus quadricauda were 24.78, 15.28 and 9.85 mg·g-1, respectively, which meant living microalgae were good adsorbent for heavy metal removal. The kinetics features of the four microalgae fitted pseudo-second order kinetics equation (R2>0.99) which showed the accumulation of heavy metals upon living microalgae were chemical primarily. Other than chemical adsorption, the accumulation included physical adsorption and biological absorption. The accumulation amount with chemical adsorption was the highest, more than 60%, among them, Chlamydomonas microsphaera was highest with 86.51%. Biological absorption with 6.75% to 18.96% and physical adsorption followed with 3.02% to 14.63%.