铀对两种小球藻生长和光合作用的影响

为了探究铀对藻类生长及光合作用的影响，筛选新的基于光合作用的水体铀污染生态风险评价指标，本试验采用不同浓度铀（0、0.5、1、5、10、20mg U·L-1）分别处理普通小球藻(Cholorella vulgaris)和黄龙普通小球藻两种来自不同生境的微藻，在处理后的第3、5、7、10、14d进行相对生长速率、光合放氧速率、叶绿素含量和叶绿素荧光动力学参数等指标的测定。结果表明：（1）0.5mg·L-1低浓度铀处理显著促进两种小球藻的生长和光合作用效率，表现为两种微藻的相对生长速率、光合放氧速率、光系统II最大光化学量子产量Fv/Fm、实际光化学量子产量Y（Ⅱ）、相对电子传递速率rETR等叶绿素荧光参数等指标均显著高于对照， 而5-20 mg·L-1高浓度铀处理则显著抑制两种小球藻的生长和光合作用；（2）黄龙普通小球藻比普通小球藻对铀处理更敏感，在1mg·L-1处理浓度下生长与光合作用就受到显著抑制，可以用来作为水体铀污染生物监测的指示生物；（3）回归分析表明，不同浓度铀处理下，叶绿素荧光参数Y(II)和rETR的响应速度快于相对生长速率、光合放氧速率、叶绿素含量和Fv/Fm等指标的变化，可以作为水体铀污染生态风险评价的敏感指标。

Effects of Uranium on the Growth and Photosynthesis of Two Types of Chlorella

In order to explore the impact of uranium on algae growth and photosynthesis, and screen new and based on photosynthetic ecological risk assessment indicators for uranium pollution in water bodies, this experiment used different concentrations of uranium (0, 0.5, 1, 5, 10, 20mg U·L-1) to treat two types of microalgae from different growth environments, Chlorella vulgaris and Huanglong Chlorella vulgaris. The relative growth rate, photosynthetic oxygen release rate, chlorophyll content, and chlorophyll fluorescence kinetic parameters were measured on the 3rd, 5th, 7th, 10th, and 14th days after treatment. The results showed that: (1) 0.5mg·L-1 low concentration uranium treatment significantly promoted the growth and photosynthetic efficiency of two types of microalgae, manifested as the relative growth rate, photosynthetic oxygen release rate, maximum photochemical quantum yield (Fv/Fm) of photosystem II, actual photochemical quantum yield Y (II), and relative electron transfer rate rETR of the two microalgae being significantly higher than the control, however, high concentration uranium treatment of 5-20 mg·L-1 significantly inhibited the growth and photosynthesis of two types of Chlorella. (2) Huanglong Chlorella vulgaris is more sensitive to uranium treatment than Chlorella vulgaris, and its growth and photosynthesis are significantly inhibited at a concentration of 1mg·L-1, and it can be used as an bioindicator for biological monitoring of uranium pollution in water bodies; (3) Regression analysis shows that under different concentrations of uranium treatment, the response speed of chlorophyll fluorescence parameters Y (II) and rETR is faster than the changes in relative growth rate, photosynthetic oxygen release rate, chlorophyll content, and Fv/Fm, which can be used as sensitive indicators for ecological risk assessment of uranium pollution in water bodies.