Algal toxicity induced by effluents from textile-dyeing wastewater treatment plants

This research aimed to evaluate the alga Scenedesmus obliquus toxicity induced by textiledyeing effluents(TDE).The toxicity indicator of TDE in alga at the physiological(algal growyth),biochemical(chlorophyll-a(Chl-a) synthesis and superoxide dismutase(SOD) activity) and structural(cell membrane integrity) level were investigated.Then we further study the relationship among toxicity indicators at physiological and biochemical level,and supplemented by research on algal biomacromolecules.According to the analysis of various endpoints of the alga,the general sensitivity sequence of toxicity endpoints of Scenedesmus obliquus was:SOD activity Chl-a synthesis algal growth.The stimulation rate of SOD activity increased from day 3(57.25%～83.02%) to day 6(57.25%～103.81%),and then decreased on day 15(-4.23%～-32.96%),which indicated that the antioxidant balance system of the algal cells was destroyed.The rate of Chl-a synthesis inhibition increased gradually,reaching19.70%～79.39% on day 15,while the rate of growth inhibition increased from day 3(-12.90%～10.16%) to day 15(-21.27%～72.46%).Moreover,the algal growth inhibition rate was positively correlated with the inhibition rate of SOD activity or Chl-a synthesis,with the correlation coefficients were 0.6713 and 0.5217,respectively.Algal cells would be stimulating to produce excessive reactive oxygen species,which would cause peroxidation in the cells,thereby destroying chloroplasts,inhibiting chlorophyll synthesis and reducing photosynthesis.With increasing exposure time,irreversible damage to algae can lead to death.This study is expected to enhance our understanding of the ecological risks through algal tests caused by TDE.     

Aggregation and ecotoxicity of CeO₂ nanoparticles in synthetic and natural waters with variable pH, organic matter concentration and ionic strength

The influence of pH (6.0-9.0), natural organic matter (NOM) (0-10 mg C/L) and ionic strength (IS) (1.7-40 mM) on 14 nm CeO₂ NP aggregation and ecotoxicity towards the alga Pseudokirchneriella subcapitata was assessed following a central composite design. Mean NP aggregate sizes ranged between 200 and 10000 nm. Increasing pH and IS enhanced aggregation, while increasing NOM decreased mean aggregate sizes. The 48 h-E_rC20s ranged between 4.7 and 395.8 mg CeO₂/L. An equation for predicting the 48 h-E_rC20 (48 h-E_rC20 = −1626.4 × (pH) + 109.45 × (pH)² + 116.49 × ([NOM]) − 14.317 × (pH) × ([NOM]) + 6007.2) was developed. In a validation study with natural waters the predicted 48 h-E_rC20 was a factor 1.08-2.57 lower compared to the experimental values.     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

水处理工艺去除藻毒素的效果探讨

探讨了饮用水处理的各工艺过程对藻毒素的去除作用,并根据前期已进行的实验对各工艺的优化组合进行了讨论,认为以气浮代替沉淀,并附之以粉末活性炭吸附预处理可有效地去除藻毒素;对没有条件改造沉淀池的水厂可暂时采用预氯化和粉末活性炭吸附组合的工艺也可达到较好的效果;对生物预处理工艺进行适当的强化,可达到对有机物、藻类、藻毒素等物质的有效去除.     

镍对纤维藻（Ankistrodesmus．sp．）毒性作用研究

本文研究了重金属镍对一种淡水绿藻──纤维藻（Ａｎｋｉｓｔｒｏｄｅｓｍｕｓ．ｓｐ．）的毒性作用．结果表明：纤维藻对镍毒作用反应敏感．镍对纤维藻的半数有效浓度９６ＥＣ５０为０．３３μｇ／ｍＬ镍，当镍浓度≥０．４μｇ／ｍＬ时，纤维藻的生长受到明显抑制，生长滞期延长，光合作用受阻，细胞膜透性增加．当镍浓度为３．２μｇ／ｍＬ时，其蛋白质氨基酸含量明显下降．     

稳定塘中氧传递规律研究

在稳定塘污水处理过程中,氧是有机物好氧分解的重要组成部分,稳定塘中氧的来源有藻类光合放氧和大气复氧。本研究通过有光无光对比试验、大气复氧试验及对实际稳定塘中运行数据进行总结研究,定量分析藻类光合产氧和大气复氧量,计算在稳定塘中有机物的总去除量中各部分所占的比例,确定出大气复氧是稳定塘中氧传递的主要方式。      

微生物控制水华藻的研究进展

水华藻的过度繁殖及引发的水生生态系统的安全问题亟待解决。随着溶藻微生物逐步发现,以微生物手段治理水华,越发得到广泛的关注和认可。在概述微生物抑藻研究现状及机理的基础上,从提高微生物对水华藻的控制效率和保障环境安全性的角度对水华的微生物防治进行了探讨,以期为实际应用微生物治理水华提供参考,并为微生物抑藻实践中可能出现的问题提供解决方法的理论依据。