三峡水库运行初期小江回水区藻类群落季节变化特点

根据对三峡小江(澎溪河)回水区2007年5月～2008年5月藻类的跟踪观测,分析了在水库蓄水运行初期小江回水区藻类的群落结构组成和演替特点.结果发现藻类的细胞密度和生物量春季最高,冬季最低,细胞密度的最高值达到421.64×105cells·L-1,而最低值只有2.06×105cells·L-1;生物量的最高值是39231.84μg·L-1,而最低值为226.17μg·L-1.从2007年5月～2008年5月在小江共鉴定出藻类7门,101属,262种,其中绿藻51属占50.5%、硅藻22属占21.8%、蓝藻18属占17.8%,此外,甲藻4属、隐藻2属、裸藻3属、黄藻及其他1属.隐藻、小球藻、小环藻、栅藻、卵囊藻、衣藻、弓形藻、直链藻、冠盘藻和针杆藻是小江回水区段的常见藻属.星杆藻、直链藻、空星藻、小球藻、栅藻、集星藻、网球藻、鱼腥藻、束丝藻、平裂藻、角甲藻、多甲藻和隐藻等12个藻属是小江回水区不同季节的优势藻属.     

水体及沉积物氮磷水平对附植藻类的影响

为了探讨湖泊富营养化过程中沉积物及水体氮、磷浓度对附植藻类的影响,通过室内模拟实验,研究了水体及沉积物氮、磷升高对苦草(Vallisnerianatans(Lour.) Hara)上附植藻类生长、群落组成及其体内氮、磷含量的影响.结果表明,在实验条件下,随着水中氮、磷含量升高,附植藻类生物量及附植藻类氮、磷含量均呈极显著增加(p0.01).随着水体可获得的氮、磷浓度升高,附植藻类的相对丰度有所变化,舟形藻(Navicula)、小球藻(Chlorella)及微囊藻(Microcystis)相对丰度随着氮、磷水平的升高而下降,直链藻(Melosira)则相反,但舟形藻、直链藻、微囊藻、小环藻(Cyclotella)和小球藻均为群落的优势属种.沉积物氮、磷含量升高对附植藻类生物量、优势种丰度及群落氮、磷含量影响较小,均未达到显著水平(p0.05).在实验条件下,沉积物氮、磷含量对附植藻类影响不大,而水体氮、磷浓度升高显著地促进了附植藻类生长.研究结果也为解释富营养化湖泊沉水植物衰退及消亡提供了一定的科学依据.     

碳素纤维对富营养化水体的水质改善与对藻类群落结构的影响

以北京朝阳区清河水为原水,开展碳素纤维生物修复试验,考察生物膜从形成到成熟及处理过程中碳素纤维外观、生物相结构、氮磷浓度及藻类群落结构的变化. 结果表明,碳素纤维在3 d内挂膜成功且生物相丰富,说明其生物亲和性强,吸附性能好. 碳素纤维生物膜对氮、磷具有较好的去除效果,TN、TP、NH₄+-N去除率分别达40%、60%、98%,其中对氮、磷的去除以吸附水体中颗粒态污染物为主. 碳素纤维生物膜对富营养化水体藻类的增殖有明显的抑制作用,尤其对蓝藻的抑制作用显著,藻类总密度和蓝藻密度达到最大值的时间与对照组相比延迟6 d,且藻类总密度及蓝藻密度都低于对照组. 碳素纤维生物膜还影响水体中的藻类群落结构,试验期间水体中以硅藻为主,蓝藻所占比例平均为22.4%,而对照组中以蓝绿藻占优,蓝藻平均所占比例高达47.2%.      

磷营养控制与藻存量削减对蓝藻水华的阻遏

通过原位实验比较了磷营养控制和藻存量削减2种方法对小型富营养化水体蓝藻水华形成早期的影响,测定了水体藻类群落结构、光合系统活性、水温、氮磷等参数的变化。结果显示:对照组水体藻类生物量从7.87 mg/L上升至14.25 mg/L,蓝藻在藻类生物量中所占比例由20%升高至40.8%,实验后期水体表面出现蓝藻局部堆积;磷营养控制组(添加钙盐)藻类生物量保持在7.53⁹.18 mg/L范围,蓝藻所占比例低于30%,后期水华控制效果明显;施用除藻剂(铜盐)可使藻类生物量迅速下降到1.88 mg/L,同时蓝藻所占比例降低至10%以下,但绿藻在后期形成优势,藻类生物量回升并超过对照组。相关性分析表明各组藻类生物量的主要限制因子分别为水温(对照)、总磷浓度(磷营养控制)和铜离子浓度(藻存量削减)。总体而言,2种方法均在水华形成早期对小型富营养化水体的蓝藻水华起到了阻遏作用。     

三峡小江回水区叶绿素a季节变化及其同主要藻类的相互关系

通过分析三峡小江回水区2007年5月～2008年4月115个样品叶绿素a的季节特点,提出了适用于表征小江回水区叶绿素a与不同藻类细胞密度和生物量的3种状态：Chla≤5 μg·L^-1、5 μg·L^-1-1和Chla>19 μg·L^-1,目的是探讨小江回水区不同水平下Chla与同期各主要藻类细胞密度和生物量的相互关系,为进一步了解三峡水库特定水域藻类季节演替特征提供参考. 全年数据下,小江回水区藻类总细胞密度、生物量和叶绿素a间均呈极显著的正相关关系（R>>0.70,Sig.≤0.01）. 研究期间小江回水区叶绿素a、绿藻、硅藻、蓝藻、甲藻生物量均值分别为(9.58±10.77)、(1605±647)、(707±124)、(511±266)和(4019±1345) μg·L^-1. Chla≤5 μg·L^-1的水平下,绿藻、硅藻与Chla浓度呈显著正相关;5 μg·L^-1-1水平下,仅有蓝藻与Chla含量呈显著正相关关系;Chla>19 μg·L^-1时,甲藻与Chla含量呈显著的正相关关系,但其它藻门与Chla含量无显著相关关系.     

水体氮磷浓度对两种沉水植物上附着藻类的影响

为了了解富营养化进程中湖泊水体氮、磷浓度升高对不同沉水植物上附着藻类的影响,通过室内模拟实验,设置3组不同氮磷浓度,研究了常见的沉水植物苦草(Vallisneria natans(Lour.)Hara)和狐尾藻(Myriophyllum spicatum L.)上附着藻类生物量及其种群组成.结果表明,附着藻类生物量随水体氮、磷浓度的升高呈显著增加的趋势;狐尾藻上附着藻类生物量均高于苦草,且随富营养化水体氮、磷浓度升高差距越来越大.不同沉水植物上藻类群落组成均以硅藻门、蓝藻门及绿藻门占优势,但优势藻组成和优势藻数量存在差异.研究结果不仅丰富了淡水水体附着藻类生态学的理论知识,也可为富营养化湖泊生态修复过程中沉水植物群落的构建提供一定的理论依据.     

三峡小江回水区磷素赋存形态季节变化特征及其来源分析

磷被普遍认为是富营养化的限制性因子,但河道型的三峡水库支流回水区在变化的水动力条件下磷的季节变化有其独特性.对2007年3月～2008年3月三峡小江回水区磷素的跟踪观测结果进行了分析.研究期间小江回水区总磷(TP)平均浓度为(61.7±2.7)μg·L~(-1),虽然各采样断面磷浓度差异不大,但其季节变化明显,大体上冬季最高、夏季较高、春季次之、秋季较低.颗粒态磷占TP平均浓度的54.05%,是TP的主要组成部分.结合同期对叶绿素a、悬浮无机颗粒物、悬浮有机颗粒物、河口流量、河口水位等主要环境变量的跟踪观测结果发现,颗粒态磷以吸附于泥沙颗粒表面或同矿质相结合的无机形态为主,并在降雨、径流的作用下进入水体使水中TP含量增加,该现象在低水位运行状态下更加明显.而在高水位运行条件下水动力条件的改变使磷素赋存形态向溶解态形式转变.小江回水区藻类生长对溶解性磷酸盐的生物利用过程十分明显,溶解性磷酸盐浓度同叶绿素a显著负相关.TP亦同叶绿素a呈负相关关系.研究认为,降雨、径流强度的加大及水位的降低虽然带来丰富的营养物,但亦使河道型的回水区水体更新周期缩短;而悬浮颗粒浓度升高导致的水体光学透射性能的下降以及洪水脉冲带来的不稳定的生长环境却阻碍了浮游植物的进一步生长和繁盛,这两方面综合作用的结果可能是小江回水区TP-Chla负相关的原因.     

重庆主城区三峡水域优势藻类的演替及其增殖行为研究

通过在三峡水系中重庆主城段的长江与嘉陵江现场布点、采样和分析自然水体中的藻类,在实验室内分别模拟氮磷比、光照和流速对嘉陵江水体中藻类生长的影响,发现在不同TN/TP和光照强度的静水环境中蓝藻和绿藻生长迅速,硅藻消亡很快,其它藻类变化不大,总藻细胞密度最大可达107/L以上;而在0.03m/s左右的缓流下总藻细胞增长最明显,但密度也只能达到106个/L,硅藻比例提高,当流速进一步加快,蓝藻和绿藻比例降低.显然,优势藻类随水文情势发生演替.总藻密度分别与TN/TP、流速拟合的可决系数R2均在0.93以上,与光照强度的拟合效果次之.自然状态下两江的现场水样分析还表明:嘉陵江总藻密度大于长江,硅藻占绝对优势,其次为绿藻和蓝藻,与实验室测试结果相符.     

草甘膦对沉积物-水界面藻类群落结构影响研究

为了探究环境中残留除草剂草甘膦对沉积物-水界面藻类群落结构演替的影响,分别以九龙江两个断面拱桥溪和石龟头的沉积物-水界面藻类群落结构为研究对象,并添加0.05 mg·L^-1草甘膦作为磷源进行实验模拟.结果表明：拱桥溪沉积物-水界面藻类生物量占比为蓝藻：绿藻∶硅藻∶甲藻=0.3%∶7.8%∶91.5%∶0.3%,蓝藻生物量占比低于1%,以硅藻门直链藻属为优势种属;石龟头沉积物-水界面藻类生物量起点占比为蓝藻∶绿藻∶硅藻∶甲藻=20.8%∶58.5%∶19.5%∶1.2%,蓝藻生物量占比大于20%,绿藻门栅藻属、蓝藻门微囊藻属和硅藻门直链藻属为优势种属.草甘膦调控15 d后,拱桥溪沉积物-水界面蓝藻生物量占比从0.3%增长到22.6%,生物量是无机磷组的7.6倍,但硅藻仍为优势门类,这与蓝藻生物量占比低于1%的拱桥溪表层水体藻类群落演替结果类似;而石龟头沉积物-水界面蓝藻生物量占比从20.8%增长到57.8%,生物量是无机磷组的近5倍,蓝藻演替为优势门类,这与蓝藻生物量占比大于15%的石龟头表层水体藻类群落演替结果相似.调控实验表明,在草甘膦胁迫下蓝藻门的增殖能力均表...     

三峡库区次级河流回水区环境因子对藻类生长影响的模拟实验研究

从三峡库区次级河流139m回水区采集水样,选用L9(34)正交表进行藻类培养试验,以Chla最大浓度作为指标选择适合藻类生长的适宜条件.结果表明,当控制水样温度为20℃、光照为8000lx、活性磷酸盐和溶解无机氮浓度分别为2.86μmol·L-1、85.71μmol·L-1时藻类生长最好;磷为限制该水域藻类生长的营养元素,藻类生长氮磷元素适宜摩尔比约为30:1.在适宜生长条件下,对数期藻细胞比生长率达到1.03d-1,稳定期Chla最大浓度达到110mg·m-3.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.