Abstract：
The first synthetic review of the PAHs effects on microalgae in experimental studies and aquatic ecosystems is provided. Phytoplankton and phytobenthos from marine and freshwaters show a wide range of sensitivities to PAHs, and can accumulate, transfer and degrade PAHs. Different toxicological endpoints including growth, chlorophyll a, in vivo fluorescence yield, membrane integrity, lipid content, anti-oxidant responses and gene expression are reported for both freshwater and marine microalgal species exposed to PAHs in culture and in natural assemblages. Photosynthesis, the key process carried out by microalgae appears to be the most impacted by PAH exposure. The effect of PAHs is both dose- and species-dependent and influenced by environmental factors such as UV radiation, temperature, and salinity. Under natural conditions, PAHs are typically present in mixtures and the toxic effects induced by single PAHs are not necessarily extrapolated to mixtures. Natural microalgal communities appear more sensitive to PAH contamination than microalgae in monospecific culture. To further refine the ecological risks linked to PAH exposure, species-sensitivity distributions (SSD) were analyzed based on published EC50s (half-maximal effective concentrations during exposure). HC5 (harmful concentration for 5% of the species assessed) was derived from SSD to provide a toxicity ranking for each of nine PAHs. The most water-soluble PAHs naphthalene (HC5 = 650 µg/L), acenaphthene (HC5 = 274 µg/L), and fluorene (HC5 = 76.8 µg/L) are the least toxic to microalgae, whereas benzo[a]pyrene (HC5 = 0.834 µg/L) appeared as the more toxic. No relationship between EC50 and cell biovolume was established, which does not support assumptions that larger microalgal cells are less sensitive to PAHs, and calls for further experimental evidence. The global PAHs HC5 for marine species was on average higher than for freshwater species (26.3 and 1.09 µg/L, respectively), suggesting a greater tolerance of marine phytoplankton towards PAHs. Nevertheless, an important number of experimental exposure concentrations and reported toxicity thresholds are above known PAHs solubility in water. The precise and accurate assessment of PAHs toxicity to microalgae will continue to benefit from more rigorously designed experimental studies, including control of exposure duration and biometric data on test microalgae.
摘要：
提供了实验研究和水生生态系统中PAHs对微藻的影响的第一个综合综述。来自海洋和淡水的浮游植物和植物底栖动物对PAHs表现出广泛的敏感性，并且可以积累，转移和降解多环芳烃。不同的毒理学终点，包括生长，叶绿素a,体内荧光产量，膜完整性,脂质含量，据报道，在培养物和自然组合中暴露于PAHs的淡水和海洋微藻物种的抗氧化反应和基因表达。光合作用,微藻进行的关键过程似乎受PAH暴露的影响最大。PAHs的影响是剂量和物种依赖的，并受环境因素如紫外线辐射的影响，温度,和盐度。在自然条件下,PAHs通常存在于混合物中,并且由单一PAHs诱导的毒性作用不一定外推到混合物中。在单特异性培养中，天然微藻群落对PAH污染似乎比微藻更敏感。为了进一步完善与PAH暴露相关的生态风险，根据已发表的EC50（暴露期间最大有效浓度的一半）分析了物种敏感性分布（SSD）。HC5(对于所评估物种的5%的有害浓度)源自SSD以提供9种PAHs中的每一种的毒性等级。水溶性最强的PAHs萘（HC5=650µg/L），萘（HC5=274µg/L），和芴（HC5=76.8µg/L）对微藻的毒性最小，而苯并[a]芘（HC5=0.834µg/L）的毒性更大。EC50和细胞生物体积之间没有关系，这不支持较大的微藻细胞对PAHs较不敏感的假设，并要求进一步的实验证据。海洋物种的全球PAHsHC5平均高于淡水物种（26.3和1.09µg/L，分别)，表明海洋浮游植物对PAHs的耐受性更高。然而，重要的实验暴露浓度和报告的毒性阈值高于已知的PAHs在水中的溶解度。PAHs对微藻毒性的精确和准确评估将继续受益于更严格设计的实验研究，包括对测试微藻的暴露持续时间和生物特征数据的控制。
