Tega-numa （Lake Tega） is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the North- chiba Water Conveyance Channel was constructed in 2000, which transfer water from Tone Rive...Tega-numa （Lake Tega） is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the North- chiba Water Conveyance Channel was constructed in 2000, which transfer water from Tone River into the lake. After 2000, the dominant species of diatoms, mainly Cyclotella sp., have been replacing blue-green algae, mainly Microcystis aeruginosa in Lake Tega. This transition of dominant species would be due to the dilution, but the detail mechanism has not been understood yet. This study examined the relationship between phosphorus fluctuation caused by river water dilution to Lake Tega and dominance of algal species, M. aeruginosa or Cyclotella sp. based on the single-species and the mixed-species culture experiments. The single-species culture experiment showed that the half-saturation constant and uptake rate of phosphorus were one order lower and seven times higher for M. aeruginosa than those for Cyclotella sp. These findings implied that M. aeruginosa would possess a potential for the growth and survival over Cyclotella sp. in the phosphorus limited condition. The superiority of M. aeruginosa was reflected in the outcome of the mixed-species culture experiment, i.e., dominance of M. aeruginosa, even phosphorus concentration was lowered to 0.01 mg-P/L. Therefore, it could be concluded that the decrease in phosphorus concentration due to the river water dilution to Lake Tega would be interpreted as a minor factor for the transition of dominant species from M. aeruginosa to Cyclotella sp.展开更多
Fluoranthene Is one of the polynuclear aromatic hydrocarbons with four benzene rings. Because of Its toxicity, mutagenlclty, and carclnogenlclty, fluoranthene Is on the black lists of 129 and 68 priority pollutants es...Fluoranthene Is one of the polynuclear aromatic hydrocarbons with four benzene rings. Because of Its toxicity, mutagenlclty, and carclnogenlclty, fluoranthene Is on the black lists of 129 and 68 priority pollutants established by US Environmental Protection Agency and the People＇s Republic of China, respectively. In recent years, the amount of fluoranthene In the aquatic environment has been Increasing with Increases In anthropogenlc discharge. Based on the biological investigation of tidal water In the Futlan mangrove, Cycioteila ~aspla was selected as the dominant algal species to determine the toxicity of fluoranthene towards C. caspla alga and to Investigate the blodegradatlon of fluoranthene by C. caspla under pure culture. The toxicity experiment showed that the 96-h EC50 value for fluoranthene was 0.2 mg/mL. Four parameters, namely C. caspla algal growth rate, chlorophyll （Chl） a content, cell morphology, and superoxlde dlsmutase （SOD） activity, were chosen as Indices of toxicity and were measured at 6 d （144 h）. The results showed that： （Ⅰ） the toxicity of fluoranthene towards C. caspla alga was obvious; （Ⅱ） C. caspla algal growth rate and Chl a content decreased with Increasing concentrations of fluoranthene; and （Ⅲ） the rate of cell deformation and SOD activity Increased with Increasing concentrations of fluoranthene. The blodegradatlon experiment showed that： （Ⅰ） the rate of physical degradation of fluoranthene was only 5.86%; （Ⅱ） the rate of blodegradatlon of fluoranthene on the 1st and 6th days （l.e. at 24 and 144 h） was approximately 35% and 85%, respectively; and （Ⅲ） the blodegradatlon capability of C. caspla alga towards fluoranthene was high. It is suggested that further Investigations on the toxicity of fluoranthene towards algae, as well as on algal blodegradatlon mechanisms, are of great Importance to use C. caspla as a biological treatment species In an organic wastewater treatment system.展开更多
Alkylphenols （APs）, the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs ...Alkylphenols （APs）, the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs are discharged into aquatic environments. Nonylphenol （NP）, the most noxious AP, is included in the blacklist of several countries. The toxicity of NP to the alga Cyclotella caspia and the biodegradation of NP by C. caspia were studied in the laboratory. The median effective concentration at 96 hr （96 hr EC50 ） of NP for C. caspia was found to be 0.18 mg/L. Five toxicity and three degradation indices were selected for toxicity and biodegradation experiments, respectively, in five or three concentrations of NP set by the 96 hr EC50 of NP. The algal growth rate and chlorophyll a contents decreased as NP concentration increased. The main manifestations of morphological deformity of the cells included volume expansion and the presence of cytoplasmic inclusions （lipid droplets）. The abnormality rate of the cells increased with NP concentration and time, and was 100% at 0.22 and 0.26 mg/L of NP after 192 hr of culture. Superoxide dismutase activity initially increased and then declined at a higher NP toxicity of greater than 0.18 mg/L. After 192 hr of culture, the biodegradation rates of NP by C. caspia with initial concentrations of 0.14, 0.18, and 0.22 mg/L were 37.7%, 31.7%, and 6.5%, respectively. The kinetic equation of C. caspia biodegradation on NP was correlated with algal growth rate and initial NP concentration.展开更多
本文利用18S r RNA基因对4株经形态学初步鉴定的梅尼小环藻(Cyclotella meneghiniana)进行了分子鉴定。结果显示,这4株分离自淡水环境(2株)和海水环境(2株)的梅尼小环藻的18S r RNA基因序列基本一致,并与已经报道的梅尼小环藻(登录号为G...本文利用18S r RNA基因对4株经形态学初步鉴定的梅尼小环藻(Cyclotella meneghiniana)进行了分子鉴定。结果显示,这4株分离自淡水环境(2株)和海水环境(2株)的梅尼小环藻的18S r RNA基因序列基本一致,并与已经报道的梅尼小环藻(登录号为GQ148712和AY496212)聚为一支,不同方法所构建的系统树的支持率分别为99%(邻接法)和98%(最大似然法),表明这4株来自不同环境的藻为同一物种——梅尼小环藻。随后作者利用扫描电镜技术在亚显微水平上对这4株梅尼小环藻进行了观察,结果显示:梅尼小环藻淡水株和海水株具有相当不同的亚显微结构特征。生活在海水的梅尼小环藻藻株具有更大的细胞以及更多的中央支持突。此外,本文还对造成梅尼小环藻种内高水平形态差异的原因以及18S r RNA基因序列是否可以作为小环藻属物种鉴定的分子标记做了分析和讨论。展开更多
文摘Tega-numa （Lake Tega） is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the North- chiba Water Conveyance Channel was constructed in 2000, which transfer water from Tone River into the lake. After 2000, the dominant species of diatoms, mainly Cyclotella sp., have been replacing blue-green algae, mainly Microcystis aeruginosa in Lake Tega. This transition of dominant species would be due to the dilution, but the detail mechanism has not been understood yet. This study examined the relationship between phosphorus fluctuation caused by river water dilution to Lake Tega and dominance of algal species, M. aeruginosa or Cyclotella sp. based on the single-species and the mixed-species culture experiments. The single-species culture experiment showed that the half-saturation constant and uptake rate of phosphorus were one order lower and seven times higher for M. aeruginosa than those for Cyclotella sp. These findings implied that M. aeruginosa would possess a potential for the growth and survival over Cyclotella sp. in the phosphorus limited condition. The superiority of M. aeruginosa was reflected in the outcome of the mixed-species culture experiment, i.e., dominance of M. aeruginosa, even phosphorus concentration was lowered to 0.01 mg-P/L. Therefore, it could be concluded that the decrease in phosphorus concentration due to the river water dilution to Lake Tega would be interpreted as a minor factor for the transition of dominant species from M. aeruginosa to Cyclotella sp.
基金Supported by the National Natural Science Foundation of China （20307012）.
文摘Fluoranthene Is one of the polynuclear aromatic hydrocarbons with four benzene rings. Because of Its toxicity, mutagenlclty, and carclnogenlclty, fluoranthene Is on the black lists of 129 and 68 priority pollutants established by US Environmental Protection Agency and the People＇s Republic of China, respectively. In recent years, the amount of fluoranthene In the aquatic environment has been Increasing with Increases In anthropogenlc discharge. Based on the biological investigation of tidal water In the Futlan mangrove, Cycioteila ~aspla was selected as the dominant algal species to determine the toxicity of fluoranthene towards C. caspla alga and to Investigate the blodegradatlon of fluoranthene by C. caspla under pure culture. The toxicity experiment showed that the 96-h EC50 value for fluoranthene was 0.2 mg/mL. Four parameters, namely C. caspla algal growth rate, chlorophyll （Chl） a content, cell morphology, and superoxlde dlsmutase （SOD） activity, were chosen as Indices of toxicity and were measured at 6 d （144 h）. The results showed that： （Ⅰ） the toxicity of fluoranthene towards C. caspla alga was obvious; （Ⅱ） C. caspla algal growth rate and Chl a content decreased with Increasing concentrations of fluoranthene; and （Ⅲ） the rate of cell deformation and SOD activity Increased with Increasing concentrations of fluoranthene. The blodegradatlon experiment showed that： （Ⅰ） the rate of physical degradation of fluoranthene was only 5.86%; （Ⅱ） the rate of blodegradatlon of fluoranthene on the 1st and 6th days （l.e. at 24 and 144 h） was approximately 35% and 85%, respectively; and （Ⅲ） the blodegradatlon capability of C. caspla alga towards fluoranthene was high. It is suggested that further Investigations on the toxicity of fluoranthene towards algae, as well as on algal blodegradatlon mechanisms, are of great Importance to use C. caspla as a biological treatment species In an organic wastewater treatment system.
基金supported by the National Natural Science Foundation of China (No. 41171416)the National Hi-Tech Research and Development Program (863) of China (No. 2007AA091703)
文摘Alkylphenols （APs）, the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs are discharged into aquatic environments. Nonylphenol （NP）, the most noxious AP, is included in the blacklist of several countries. The toxicity of NP to the alga Cyclotella caspia and the biodegradation of NP by C. caspia were studied in the laboratory. The median effective concentration at 96 hr （96 hr EC50 ） of NP for C. caspia was found to be 0.18 mg/L. Five toxicity and three degradation indices were selected for toxicity and biodegradation experiments, respectively, in five or three concentrations of NP set by the 96 hr EC50 of NP. The algal growth rate and chlorophyll a contents decreased as NP concentration increased. The main manifestations of morphological deformity of the cells included volume expansion and the presence of cytoplasmic inclusions （lipid droplets）. The abnormality rate of the cells increased with NP concentration and time, and was 100% at 0.22 and 0.26 mg/L of NP after 192 hr of culture. Superoxide dismutase activity initially increased and then declined at a higher NP toxicity of greater than 0.18 mg/L. After 192 hr of culture, the biodegradation rates of NP by C. caspia with initial concentrations of 0.14, 0.18, and 0.22 mg/L were 37.7%, 31.7%, and 6.5%, respectively. The kinetic equation of C. caspia biodegradation on NP was correlated with algal growth rate and initial NP concentration.
文摘本文利用18S r RNA基因对4株经形态学初步鉴定的梅尼小环藻(Cyclotella meneghiniana)进行了分子鉴定。结果显示,这4株分离自淡水环境(2株)和海水环境(2株)的梅尼小环藻的18S r RNA基因序列基本一致,并与已经报道的梅尼小环藻(登录号为GQ148712和AY496212)聚为一支,不同方法所构建的系统树的支持率分别为99%(邻接法)和98%(最大似然法),表明这4株来自不同环境的藻为同一物种——梅尼小环藻。随后作者利用扫描电镜技术在亚显微水平上对这4株梅尼小环藻进行了观察,结果显示:梅尼小环藻淡水株和海水株具有相当不同的亚显微结构特征。生活在海水的梅尼小环藻藻株具有更大的细胞以及更多的中央支持突。此外,本文还对造成梅尼小环藻种内高水平形态差异的原因以及18S r RNA基因序列是否可以作为小环藻属物种鉴定的分子标记做了分析和讨论。
