稀土元素对小球藻叶绿素（a）含量及其亚显微结构的影响

为了解稀土元素的水生生物效应，通过小球藻的培养试验，研究了若干轻稀土元素镧（La）、铈（Ce）、镨（Pr）、钕（Nd）及其混合物对椭圆小球藻（chlorellaellipsoidea）的生理影响。结果显示，低浓度（2～10mg/L）稀土元素在短期内（1～3d）对小球藻叶绿素（a）含量的增长有轻微的刺激促进作用，但随着处理浓度的提高和时间的延长，小球藻叶绿　素（a）含量的增长明显受到抑制，当稀土浓度≥100gm/L时，其叶绿素（a）含量基本处于负增长，小球藻生长停滞，趋于死亡，此时其细胞亚显微结构遭到破坏，尤以叶绿体结构的变化最为明显。4种稀士元素及其混合物对小球藻的毒性尚属中等。

Effects of rare-earth elements on Chlorophyll (a) contents and ultrastructure of Chlorella ellipsoidea

In order to find out effects of rare-earth elements on aquatic organisms, the physiological effects of some light rare-earth elements (La, Ce, Pr, Nd and their mixtures)on Chlorella ellipsoidea were studied by means of aquaculture test. The results show that lower concentration(2-10mg/l) of rare-earth elements stimulates lightly chlorophyll (a) contents of Chlorella ellipsoideaat the beginning of test, but inhibites it apparently as treating concentration increases and time prolongs. While the concentration of rare-earth elements>=100mg/l, chlorophyll (a) contents increases negatively, and Chlorella ellipsoidea stagnates growth and tends to die; in the meantime, the ultrastructure of Chlorella ellipsoidea, especially chloroplast, is destroyed obviously. The toxicities of La, Ce, Pr, Nd and their mixtures on Chlorella ellipsoidea are of medium levels.