农药在现代农业中起着非常重要的作用，然而大量使用农药导致了其在环境中的残留，造成了环境的污染，也影响了非靶标生物的生长。异丙隆是一种广泛应用的取代脲类除草剂，近年来在水生环境中经常能够检测到异丙隆的残留。为了评估异丙隆对水生植物的毒性以及在水生态环境中的归趋，本论文研究了异丙隆对模式生物莱茵衣藻的生理毒性以及莱茵衣藻对异丙隆的生物富集、生物降解作用。研究结果对了解异丙隆对水生态环境的危害性，认识异丙隆对水环境结构和功能的整体效应以及其迁移转化规律，同时为探索监测水生态系统农药污染提供一定的科学数据。 为了研究异丙隆处理对莱茵衣藻的生长的影响，实验设定了5个浓度梯度5，15，25，35和50 µg L-1<上标!> 以及不加异丙隆的空白对照，测定细胞密度和叶绿素含量的变化。结果表明，异丙隆处理抑制了莱茵衣藻的生长，细胞密度和叶绿素含量都有所减少，随着异丙隆处理浓度的升高，这种抑制作用逐渐增强。这两种测定指标均可以用作评价异丙隆对莱茵衣藻毒性大小的理想指标。同时也研究了培养时间变化与毒性的关系，结果发现随着培养时间的延长，藻细胞对环境的适应性使得异丙隆对莱茵衣藻生长的抑制作用逐渐减弱。为了评估不同浓度异丙隆处理对莱茵衣藻光合作用的抑制，实验测定了叶绿素荧光参数Fv/Fm和Yield的变化情况，结果也呈现浓度相关性。 论文研究了异丙隆对莱茵衣藻的活性氧胁迫及响应机制。实验发现在异丙隆浓度处理范围内（5~50 µg L-1<上标!>），藻细胞内活性氧（ROS）被诱导过量产生，进而引发细胞内膜质过氧化作用，TBARS物质丙二醛含量与没有添加异丙隆的对照相比明显升高。处理浓度越高，丙二醛含量就越高。藻细胞内过量的 ROS 激活了细胞内抗氧化物岐化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX），它们作为抗氧化酶系共同作用以消除细胞中过量 ROS，从而降低甚至消除活性氧伤害。同时，细胞内重要的解毒酶谷胱甘肽转移酶（GST）被激活。半定量PCR的结果证实了与SOD，CAT, APX活性相关的基因在转录水平上受到调控，调控程度与酶活力的变化趋势基本吻合。半定量PCR结果还发现血红素加氧酶HO-1基因被ROS激活，表达量与异丙隆浓度正相关。 最后论文研究了莱茵衣藻对异丙隆的生物富集和降解作用。在初始异丙隆添加浓度为550 μg L-1<上标!>范围内，莱茵衣藻可以通过生物富集作用降低培养基中的异丙隆含量。随着处理浓度的提高，藻中异丙隆的富集量呈现增加的趋势。生物富集因子（BCF）随着处理浓度的升高而逐渐减小，在5 μg L-1<上标!>时，生物富集能力最强，BCF达到284.24；随着培养时间的延长，藻中积累的异丙隆含量逐渐升高，培养时间为1, 2, 3, 4, 5和6 d时，藻中积累量分别达到0.54、0.51、1.30、1.47、1.88、2.23 μg g-1<上标!>。BCF值逐渐升高，第六天已经增加到135.70。实验表明莱茵衣藻对异丙隆也具有一定的降解能力。高浓度处理时具有较高的生物降解率。并且随着培养时间的延长，莱茵衣藻对异丙隆的降解能力也明显提高，到第六天时，已经有12.1% 的异丙隆被降解。

Pesticides play an important role in modern agriculture. However, the wide use of pesticides has brought the residue and pollution in environment. The pesticide residue may affect the non-targets in the environment. Isoproturon (IPU) is a widely used phenylurea derived systemic herbicide that has been detected in aquatic environment in recent years. To evaluate the eco-toxicity of isoproturon to aquatic plants and its fate in the aquatic environment, this paper studied the eco-toxicity of isoproturon to the model organisms Chlamydomonas reinhardtii and the ability of bioaccumulation and biodegration of Chlamydomonas reinhardtii to IPU. This can help us understand the harm of IPU to aquatic environment, the overall effect of IPU on the structure and function of aquatic environment and its migration pattern. This could also provide some basis to the monitoring of pesticide contamination in aquatic ecosystems. The algae were cultivated with IPU at 0, 5, 15, 25, 35 and 50 μg L-1<上标!> for 3 days. The cell density and chlorophyll content of Chlamydomonas reinhardti were determinated. The results showed that isoproturon inhibited the growth of Chlamydomonas reinhardtii, and reduced cell density and chlorophyll content of Chlamydomonas reinhardtii. The inhibition gradually increased with the treatment concentration of IPU. The cell density and chlorophyll content were found to be ideal indicators to evaluate the toxicity of isoproturon to Chlamydomonas reinhardtii. Algae were incubated with IPU 25 μg L-1<上标!> in time-denpendent experiments. A declined toxicity with the exposure time was also observed in this study. When the algae exposed to IPU, the photosynthesis was inhibited. The decline of chlorophyll fluorescence parameters namely Fv/Fm and Yield were concerned with the concentration. The reaction of C. reinhardtii to oxidative stress induced by IPU was investigated. Production of reactive oxygen species (ROS) was observed when the miroalgae were exposed to IPU with the concentration ranged from 5 to 50 μg L-1<上标!>. The result showed an increase in thiobarbituric acid reactive substances (TBARS) with the treatment concentration of IPU. To deal with oxidative damage and remove excessive ROS, activities of antioxidant enzymes in C.reinhardtii substantially changed. The activities of SOD, CAT, APX and GST in C. reinhardtii were increased treated with IPU. A RT-PCR-based assay was performed to analyze the transcript abundance of SOD, APX, CAT and HO-1. The result was showed that the expression of SOD, APX and CAT was up-regulated by IPU exposure, with a pattern similar to the antioxidant enzyme activities. The up-regulation of HO-1 expression in the cells exposed to IPU revealed in a concentration-dependent manner. Furthermore, the amount of IPU in algae and culture medium and the bioaccumulation and biodegration capability of C. reinhardtii to IPU were determined. The results were showed that C.reinhardtii could accumulate and concentrate IPU. After 72 h exposure with IPU, accumulation of IPU in C.reinhardtii was added with increases in initial IPU levels. The significantly larger BCFs were observed at low levels of IPU. The BCF reached the peak level of 284.24 after exposure to IPU at 5 μg L-1<上标!>. BCFs were increased with exposure time and reached the maximum value of 135.70 on day 6 . The amount of IPU accumulated in the microalgae during 1, 2, 3, 4, 5 and 6 days were respectively 0.54, 0.51, 1.30, 1.47, 1.88 and 2.23 μg g-1<上标!>. The biodegradation of isoproturon in C. reinhardtii is very limited during the short time exposure. The capacity of biodegradation was enhanced at higher IPU lever. The biodegradation percentage of IPU at 25 μg L-1<上标!> increased with the exposure time. On day 6, 12.1% of IPU was decreased by biodegradation.