Early stage toxicity of excess copper to photosystem II of Chlorella pyrenoidosa-OJIP chlorophyll a fluorescence analysis

Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short period of time.High Cu concentration resulted in a significant suppression in photosynthesis and respiration.The absorption flux (ABS/RC) per PSⅡ reaction center increased with increasing Cu concentration,but the electron transport flux (ET_0/RC) decreased.Excess Cu had an insignificant effect on the trapping flux (TR_0/RC).The decline in the efficiency with which a trapped exciton can move an electron into the electron transport chain further than QA- (ψ_o),the maximal quantum yield of primary photochemistry (φP_o),and the quantum yield of electron transport (φE_o) were also observed.The amount of active PSⅡ reaction centers per excited cross section (RC/CS) was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration.JIP-test parameters had a good linear relationship with photosynthetic O_2 evolution.These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSⅡ reaction centers and inhibition of electron transport in the acceptor side.     

利用络合铜控制水华优势藻的试验研究

试验研究了络合铜对蓝藻水华优势藻铜绿微囊藻和绿藻水华优势藻普通小球藻的杀藻抑藻效果。试验结果表明,络合铜对铜绿微囊藻的抑制作用优于对小球藻的抑制作用。当投加1mg/L以上络合铜络合时对铜绿微囊藻有很好的杀灭作用,但投加浓度提高到5mg/L时才能有效抑制普通小球藻的生长。同时还开展了络合铜对青鳉鱼的急性毒性试验,得出了络合铜的半致死浓度分别为24hLC50=8.5mg/L;48hLC50=5.7mg/L;96hLC50=3.9mg/L。     

蛋白核小球藻(Chlorella pyrenoidosa)微板毒性分析方法优化

以蛋白核小球藻(Chlorella pyrenoidosa,CP)为指示生物,96孔微板为暴露载体,污染物对藻的72 h生长抑制率为毒性指标,通过系统地检测蛋白核小球藻的生长曲线和吸收光谱,确定藻细胞密度和683 nm波长处光密度(D₆₈₃)之间的线性关系,考察不同初始藻密度、照度、暴露时间和暴露体积对藻生长的影响,建立了蛋白核小球藻微板毒性分析方法(CP-MTA法).将CP-MTA法应用于重金属盐、除草剂、杀虫剂以及离子液体等8种化学品对蛋白核小球藻的生长抑制毒性测试,以pEC₅₀为毒性指标,毒性大小顺序为敌草快>CuSO₄·5H₂O≈CdCl₂·2.5H₂O>氯化1-甲基-3-辛基咪唑(［Omim］Cl)>草甘膦>氯化1-甲基-3-丁基咪唑(［Bmim］Cl)>敌敌畏>乐果,与文献结果一致.CP-MTA法由于以微板为反应载体,所需样品少,便于多次平行,数据重复性好.      

脱水红霉素对蛋白核小球藻的生态毒性效应研究

脱水红霉素是环境中普遍存在的一种大环内酯类抗生素,其生态毒性效应尚不明确。因此,以蛋白核小球藻(Chlorella pyrenlidosa)为受试生物,研究了脱水红霉素对绿藻的生长、叶绿素a含量、抗氧化酶活性和丙二醛(MDA)含量的影响。结果表明,脱水红霉素对蛋白核小球藻的生长具有抑制作用,且随暴露浓度的升高而增强。脱水红霉素对蛋白核小球藻的96 h比生长率半数抑制浓度(E_rC_(50))和生长量半数抑制浓度(E_yC_(50))分别为0.267和0.117 mmol·L~(-1),属于中-低毒物质。脱水红霉素暴露对蛋白核小球藻的叶绿素a含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和MDA含量具有重要影响。叶绿素a含量随脱水红霉素浓度升高而降低; SOD酶活性升高,但与脱水红霉素浓度之间不存在剂量效应关系,CAT酶活性和MDA含量随脱水红霉素升高而升高,说明脱水红霉素对蛋白核小球藻具有氧化胁迫效应。暴露96 h后,藻液中脱水红霉素的去除率随其初始浓度增加而增加,在脱水红霉素初始浓度为0.87 mmol·L~(-1)时,其去除率可达到43%。研究结果可为脱水红霉素的生态风险评估提供理论依据。     

不同粒径和不同浓度清洁疏浚物对2种海洋微藻生长的影响

采用室内模拟试验研究了不同粒径和不同浓度悬浮清洁疏浚物对2种常见海洋微藻小球藻（Chlorella sp.）和新月菱形藻（Nitzschia closterium）生长的影响.结果表明,在8d的试验周期里,与对照组相比,不同浓度清洁疏浚物对2种海洋微藻生长的影响均达极显著水平（P＜0.01）.在相同粒径范围内,悬浮清洁疏浚物质量浓度为1～7g·L-1时,其对微藻生长的抑制作用随浓度升高而增加.随悬浮清洁疏浚物粒径的减小,2种海洋微藻的细胞密度呈下降趋势,＞88～ 125 μm粒径范围内生长的藻细胞受影响最小,0～16 μm粒径范围内生长的藻细胞受影响最大.悬浮清洁疏浚物对2种海洋微藻比生长速率的抑制作用明显,延缓了最大比生长速率出现的时间.2种海洋微藻对悬浮清洁疏浚物的敏感性存在差异,小球藻对悬浮清洁疏浚物的反应更加迅速.     

Evidence for Atmospheric Deposition Impacts On the Enchytraeid Worm Population of Uk Upland Ombrotrophic Peats

The results of four experiments on acidification effects upon the Enchytraeid worm populations of ombrotrophic peats are reported. in the first, populations were measured in peats from Calluna vulgaris-dominated microcosms collected from along a gradient in N deposition in the UK and subjected for 18 months to simulated precipitation with a solute composition appropriate for their site of collection. There was a significant decline in Enchytraeid population along the N deposition gradient for Calluna-dominant microcosms, but when grasses took over from the Calluna, Enchytraeid numbers increased significantly. in the second experiment, two sets of peat moorland microcosms from a single site, supporting Calluna and Calluna-grass mixed vegetation, were subjected for 12 months to ambient and 2- and 6-times the ambient N deposition. Additional N was added in two forms, as ammonium sulphate and as nitric acid. the high N treatments significantly reduced the Enchytraeid populations for both vegetation types. in a third experiment, the pH preference for the Enchytraeids was assessed using interconnected tubes of peat covering the pH range 2.2–8.7. the preferred pH range after 8 months was 2.7–3.7. in the final experiment, it was found that recolonization with Enchytraeids after initial removal was more rapid under grass dominant vegetation than under Calluna dominant vegetation.     

壬基酚在蛋白核小球藻和大型溞体内的富集与传递

为探究壬基酚(nonylphenol,NP)在水生生物中的富集传递效应,选择以蛋白核小球藻(Chlorella pyrenoidosa)和大型溞(Daphnia magna)为研究对象,开展蛋白核小球藻对NP的富集效应实验,及NP在蛋白核小球藻和大型溞体内的传递效应实验。研究结果表明,NP对蛋白核小球藻的96 h半数效应浓度(96 h-EC50)为3.13 mg·L~(-1),对蛋白核小球藻的生长和叶绿素含量的影响呈现明显的剂量-时间效应。NP对大型溞的48 h半数效应浓度(48 h-LC50)为37.41μg·L~(-1),属于高毒类化合物。蛋白核小球藻暴露于0.05 mg·L-1NP 4 h后,其生物富集系数(BCF)为5 144.93,富集量为252.2μg·g~(-1),在12 h内对NP的生物富集系数(BCF)最高达12 053.64,富集量为1 181.73μg·g~(-1)。以0.05 mg·L-1NP中暴露4 h后的蛋白核小球藻为饵料投喂大型溞7 d后,大型溞体内NP富集量最高达3.6μg·g~(-1)。0.05 mg·L~(-1)NP直接暴露组大型溞暴露10 d后,大型溞体内NP富集量最高达4.02μg·g~(-1)。蛋白核小球藻对NP具有较强的富集能力,能够通过摄食过程将NP传递到大型溞,经传递的NP能够显著抑制大型溞的生长、繁殖、摄食等生命活动。论文为评估NP在水生生态系统中的污染风险和富集传递效应提供了一定的参考依据。     

纳米二氧化钛和单壁碳纳米管对普通小球藻生长的抑制效应(Effects of Nano-TiO2 and Single-Walled Carbon Nanotubes on the Growth of Chlorella vulgaris)

纳米材料独特的理化性质使其得到了广泛的应用,但其可能带来的生物安全性问题引起了社会各界的广泛关注.采用污染物藻类毒性测试的标准实验方法,研究了纳米二氧化钛(nano-TiO2)和单壁碳纳米管(SWCNTs)对普通小球藻(Chlorella vulgaris)生长的抑制效应.结果表明,在0.01～500mg·L-1浓度范围内,nano-TiO2对普通小球藻的生长没有明显的抑制现象,而SWCNTs却对普通小球藻的生长存在明显的抑制效应,其96h半效应浓度(96h-EC50)为261.5mg·L-1.光学和电子显微镜观察发现,与nano-TiO2相比,SWCNTs能够发生凝聚并吸附大量的普通小球藻细胞,因此严重抑制了普通小球藻的正常生长.     

芦苇生物活性组分对小球藻生长的促进效应

利用乙醇从芦苇(Phragmites australis)生物质中提取得到具有生物活性的粗提液,研究了芦苇乙醇粗提液对蛋白核小球藻生物量、叶绿素含量、蛋白质含量的影响.结果表明,芦苇中存在的生物活性组分对蛋白核小球藻的生物量、叶绿素含量、蛋白质含量的提高均具有促进效应,层析中性组分可使小球藻藻密度平均提高0.87倍,最高可提高1.79倍,叶绿素含量及蛋白质含量平均提高0.67倍和0.99倍,最高可提高2.71倍和4.76倍.芦苇中存在的高价值生物活性物质具有很好的开发及应用潜力.     

改进的PVA-硫酸盐法固定蛋白核小球藻除磷研究

首次报道采用改进后的PVA-硫酸盐固定化方法,包埋固定蛋白核小球藻.该方法克服了现有的几种PVA固定化包埋过程的缺点.其操作过程简单,形成的凝胶小球不黏连,透光性好,对生物毒性小,机械强度高.经固定的蛋白核小球藻在光照条件下对磷的去除率达95%,3个周期后,磷去除率仍可达到75%以上,凝胶小球强度没有明显降低.实验证明,光照是影响固定化蛋白核小球藻除磷的主要因素,光暗比12:12与24h全光照的两组对磷的最高去除率没有明显差别,但光暗比12:12的一组去除率有波动.透射电镜观察结果表明,PVA与细胞壁紧密粘贴,蛋白核小球藻生长没有停止.