两种抗生素对塔玛亚历山大藻生长和产毒的影响

论文以中国南海筛选的一株塔玛亚历山大藻Alexandrium tamarense C101为研究对象,研究了两种抗生素,氨苄青霉素(ampicillin,Amp)和新霉素(neomycin,Nm)对A.tamarense C101细胞生长、形态以及毒素含量的影响.结果表明:和空白对照组相比,经1 500μg/mL Nm...     

藻类水体Cd2+毒性快速监测新方法研究

采用藻类生长抑制试验和光合活性抑制试验两种方法对蛋白核小球藻受不同浓度Cd2+胁迫作用下叶绿素浓度及藻活性荧光参数进行测量,依据Sigmoidal曲线拟合及单因素方差分析(one-way ANOVA)的方法对Cd2+不同胁迫时间下藻活性抑制率和96 h比生长率抑制率的相关性进行研究.结果表明,48、53、72、77和96 h的藻活性抑制率和96 h比生长率抑制率间具有较好的S函数关系(R2>0.95),因此可采用藻活性抑制率48 h-EC10和53 h-EC10来代替96 h的藻类半数比生长率抑制率EC50进行Cd2+藻类毒性实验评价.进一步分析了蛋白核小球藻受Cd2+胁迫48 h和53 h藻活性抑制率和Cd2+毒性当量的剂量-效应关系.该方法为实验室内单一Cd2+毒性的监测提供了一种快速有效的新方法,为水环境综合毒性预警提供了一种切实可行的方法依据.     

表面活性剂Burkholderia xenoborans LB400体系对低氯代PCBs的好氧强化降解

增强多氯联苯(PCBs)的水溶性是强化PCBs微生物降解的主要控制因素之一,本研究选取了PCB5(2,3-CB)和PCB31(2,4',5-CB)作为低氯代PCBs的典型代表,以曲拉通100(TX-100)、吐温80(Tween 80)、鼠李糖脂粗提物(RL crude)3种表面活性剂和β-环糊精( HPCD)联合Burkholderia xenoνorans LB400构建PCBs好氧降解体系,测试了它们对PCB5和PCB31的溶出率及微生物生长的影响.结果表明,TX-100(CMC＝194 mg·L-1)、 Tween 80(CMC＝13.1 mg·L-1)、 RL crude(CMC＝50 mg·L-1)浓度在1~7 CMC 时和 HPCD 浓度在500~1500 mg·L-1时对 PCB5和 PCB31溶出率分别达到54.7％~100％、59.8％~100％;10.5％~40.8％、6.8％~31.6％;10.3％~19.9％、3.3％~11.6％和19.5％~34.2％、4.2％~10.7％. TX-100浓度在1~7 CMC时对B. xenoνorans LB400生长的抑制率达到30.3％~45.8％,而Tween 80浓度在0.1~1 CMC时对其生长的抑制率为10.0％~15.4％; RL crude 本身能作为底物促进 LB400的生长,而 HPCD 对其生长无明显影响. B. xenoνorans LB400对PCB31(5 mg·L-1)的降解效率在添加表面活性剂后有不同程度的提高：TX-100,23.7％~65.5％; Tween 80,14.6％~44.3％;RL crude,9.6％~27.2％;HPCD,15.3％~20.7％;而表面活性剂对PCB5(10 mg·L-1)的降解效率则无明显影响.表面活性剂主要通过增大溶液中PCBs-表面活性剂的胶束浓度来提高LB400对PCBs的降解效率,在水溶液培养体系中当设置TX-100和Tween 80浓度分别在1和7 CMC时,PCB31的降解效率达到100％和81.7％,而此时B. xenoνorans LB400生长的抑制率为30.3％和5.4％.     

宝鸡市经济增长与环境空气综合污染指数关系研究

文章以空气综合污染指数法分析了宝鸡市2006年-2011年的环境空气质量状况,分析结果表明宝鸡市环境空气质量逐年变好。以人均GDP为经济指标,以空气综合污染指数为环境指标,建立经济增长与环境空气质量之间的计量模型,进行环境库兹涅茨曲线实证研究。研究结果表明,宝鸡市经济增长和环境空气质量的关系符合库兹涅茨曲线"拐点"后的下降部分。证明该市2006年-2011年的环境空气质量与人均GDP处于良性发展状态。     

千岛湖水源水微生物安全性评价

千岛湖作为国家战略水源地,其微生物安全直接关系到千万居民的用水安全.为了研究千岛湖湖水的生物安全性,于2018-2019年采集了金竹牌取水口不同深度的水样,并检测了水样的可生物降解溶解性有机碳(BDOC)、细菌再生长的潜力(BGP)、可培养细菌数、潜在的条件致病菌和细菌群落结构.结果显示,千岛湖水质属地表水Ⅱ～Ⅲ类水,...     

不同光照时间对杏鲍菇生长发育的影响

为探究光照时间对杏鲍菇生长发育的影响,设置蓝、白两种光质,每种光质下设置5种不同光照时间处理进行栽培试验,并测定每个处理下杏鲍菇原基形成与分化速度、菇蕾与子实体形态、产量及可溶性蛋白质与总糖含量.结果显示,原基形成速度随光照时间增加呈现先增加后降低的趋势,蓝光下以15 min光照15 min黑暗时间处理下原基形成速度最...     

Protection of ash (Fraxinus excelsior) trees from ozone injury by ethylenediurea (EDU): roles of biochemical changes and decreased stomatal conductance in enhancement of growth

Treatments with ethylenediurea (EDU) protect plants from ozone foliar injury, but the processes underlying this protection are poorly understood. Adult ash trees (Fraxinus excelsior), with or without foliar ozone symptoms in previous years, were treated with EDU at 450ppm by gravitational trunk infusion in May-September 2005 (32.5ppmh AOT40). At 30-day intervals, shoot growth, gas exchange, chlorophyll a fluorescence, and water potential were determined. In September, several biochemical parameters were measured. The protective influence of EDU was supported by enhancement in the number of leaflets. EDU did not contribute its nitrogen to leaf tissue as a fertiliser, as determined from lack of difference in foliar N between treatments. Both biochemical (increase in ascorbate-peroxidase and ascorbic acid, and decrease in apoplastic hydrogen peroxide) and biophysical (decrease in stomatal conductance) processes regulated EDU action. As total ascorbic acid increased only in the asymptomatic trees, its role in alleviating O(3) effects on leaf growth and visible injury is controversial.     

Characterization of the toxic effects of cadmium and 3.5-dichlorophenol on nitrifying activity and mortality in biologically activated sludge systems—effect of low temperature

Background, aims, and scope  Sometimes, urban wastewaters convey a more or less significant part of toxic products from industries or the craft industry. Nitrifying activity can be affected by these substances, implying higher ammonia concentrations in the outlet effluent and contributing to toxicity for the aquatic environment. Moreover, the more stringently treated wastewater standards now require a reliable treatment for nitrogen. One of the key issues is the identification of the inhibition behavior of nitrifying bacteria facing a toxic substance. This new understanding could then finally be integrated into models in order to represent and to optimize wastewater treatment plants (WWTP) operation in cases involving ‘toxic scenarios’. Materials and methods  The toxic substances studied in this work, cadmium and 3.5-dichlorophenol (3.5-DCP), are representative of chemical substances commonly found in municipal sewage and industrial effluents and symbolize two different contaminant groups. The effects of Cd and 3.5-DCP on nitrification kinetics have been investigated using respirometry techniques. Results  IC50 values determination gives concentrations of 3.1 mg/L for 3.5-DCP and 45.8 mg/L for Cd at 21 ± 1°C. The variation to low temperature seems to have no real effect on IC50 for DCP, but induces a decrease of cadmium IC50 to 27.5 mg/L at 14°C. Finally, specific respirometric tests have been carried out in order to determine the potential effect of these toxic substances on the nitrifying decay rate b _a . No significant effect has been noticed for Cd, whereas the presence of 3.5-DCP (at IC50 concentration) induced a dramatic increase of b _a at 20°C. The same behavior has been confirmed by experiments performed in winter periods with a sludge temperature around 12°C. Discussion  The target substances have different modes of action on activity and mortality, notably due to the abilities of the contaminant to be precipitated, accumulated, or even to be progressively degraded. Studies realized at low temperature confirmed this assumption, and put in evidence the effect of temperature on toxic substances capable of being biosorbed. However, the change in the sludge sample characteristics can be pointed out as a problem in the investigation of the temperature effect on nitrification inhibition, as biosorption, bioaccumulation, and predation are directly linked to the sludge characteristics (VSS concentration, temperature) and the plant operating conditions (loading rates, sludge age, etc.). Conclusions  This work brings new understandings concerning the action mode of these specific contaminants on nitrifying bacteria and, in particular, on the role of temperature. The experiments lead to the determination of the IC50 values for both toxic substances on biological nitrification. The inhibition mechanisms of Cd and 3.5-DCP on nitrifying activity have been simply represented by a non-competitive inhibition model. Recommendations and perspectives  Other experiments carried out in a continuous lab-scale pilot plant should be done with a proper control of the operating conditions and of the sludge characteristics in order to better understand the mechanisms of nitrification inhibition for each contaminant. Finally, these first results show that toxic substances can have an effect on the growth rate but also on the decay rate, depending on the characteristics of the toxic substance and the sludge. This eventual double effect would imply different strategies of WWTP operation according to the behavior of the contaminant on the bacteria.     

家用洗衣粉中磷对斜生栅藻生长的影响

以洗衣粉中的有机磷为磷源,通过室内模拟的方法研究在不同磷浓度的水体条件下斜生栅藻的生长情况,以及磷对斜生栅藻的生长是否有毒害作用.通过显微计数测定藻细胞数目来探讨洗衣粉中磷对斜生栅藻生长的影响;同时分析了洗衣粉中磷对斜生栅藻96 h生长期中光合色素的影响.结果表明,洗衣粉中的磷除了促进藻生长外,其浓度过低或过高都会抑制藻的生长.由实验结果可得,磷对藻生长的富营养化作用和毒性作用取决于磷浓度的高低.     

Physicochemical substance properties as indicators for unreliable exposure in microplate-based bioassays

In the last years many efforts were made to transform standardized algal test protocols into low-cost microplate assays. While advantages were pointed out frequently, limitations are not systematically addressed, thus hindering a widespread utilisation. In this study a group of organic substances with a wide distribution of volatility (log K_AW from −6.53 to −2.13) and lipophilicity (log K_OW from 1.26 to 4.92) was investigated with respect to the influence of these physicochemical properties on their algal toxicity in different assays. Therefore the EC₅₀ values were determined with a microplate assay based on ISO 8692 protocol and the results were compared with those of an established algal growth inhibition test conducted in air tight glass vessels. Using the ratio of the EC₅₀ values, a clear connection between biological response and volatility as well as lipophilicity of test substances could be detected. Chemicals with a log K_OW higher than 3 or a Henry coefficient log K_AW higher than −4 were identified as less effective in the microplate assay than in the comparative assay. The loss in nominal concentration due to physicochemical properties could be shown to contribute to this using HPLC analysis. Consequently, when using microplate assay’s one should be aware that lipophilic and volatile chemicals might be underestimated in their toxicity, which could be indicated from evaluating related physicochemical properties modelled from structural information prior to an experimental investigation.