表流人工湿地中芦苇对重金属的吸收和累积

为了研究人工湿地植物中重金属的累积和分布,对中试规模湿地植物(芦苇)中6种重金属Cd、Cr、Cu、Ni、Pb和Zn进行取样和分析。结果表明:湿地芦苇中Zn、Cu和Cr的质量分数沿着湿地入口的前3个采样点显示出下降趋势,即在离进水较近的约30 m区域内,芦苇对重金属的吸收最明显。芦苇各部位中Cu的分布显示为根>茎>叶;其他5种重金属的分布为根>叶>茎,则根中重金属质量分数远大于茎和叶。芦苇根易于富集Cd和Cu,对Cr的富集能力较弱;芦苇中除Cr以外,其他5种重金属由根向叶的迁移能力大于由根向茎的转移能力,且Cu和Zn从芦苇根向地上部位的迁移能力较强。     

湿地植物芦苇(Phragmites australis)的重金属富集能力与评价

以江苏盐城海岸带的原生湿地植物芦苇(Phragmites australis)为研究对象,检测了Hg、As、Cu、Zn、Pb、Ni、Cd、Cr共8种重金属在其茎叶和根系部分的含量。结果表明,芦苇植物体对重金属的生物富集能力各异,其根系对Hg和Cr的富集能力较大,其茎叶则表现为对Hg的富集能力较大;芦苇植物体对于8种重金属的转运系数均小于1,其中转运系数最大的是Cd,达到0.88。基于国家药用植物行业标准《中华人民共和国外经贸行业标准药用植物及制剂进出口绿色行业标准》,评价了该湿地植物芦苇的入药情况。结果表明,该湿地芦苇不符合药用植物入药标准。芦苇滩土壤中,Cd和Cu含量超出了土壤环境质量标准的要求,存在一定程度的Cd和Cu污染。因此,就目前芦苇开发利用状况而言,收割芦苇的行为有利于高效、经济地从湿地中转移出各种重金属污染物。芦苇可以作为受污染滨海湿地生态系统的修复植被,利用其高生产力,通过秸秆收割来达到净化湿地环境的效果。     

纳污湿地植物对底泥重金属吸收特性研究

对武河湿地两种主要植物——芦苇和菖蒲不同组织及其底泥中Cu、Zn、Cd、Pb 4种重金属元素的含量进行了测定,结果表明:4种重金属元素在两种植物中的含量表现为Cu(628.51 mg/kg)Zn(578.05 mg/kg)Pb(32.01 mg/kg)Cd(11.71 mg/kg),但同一种元素在植物体不同组织中的含量有较大的差异;芦苇对于4种重金属元素的转移能力表现为ZnCuPbCd,富集能力表现为ZnCuCdPb,菖蒲对于4种重金属元素的转移能力表现为ZnCdPbCu,富集能力表现为ZnCdCuPb;芦苇处理Cu、Zn复合污染及Cd污染的污水效果较好,菖蒲净化Zn污染及Cd污染的水体效果较好,二者对于Pb元素的净化能力有限;相关分析表明,芦苇茎部对于碳酸盐结合态Pb元素的吸收效果良好,芦苇根部对于残渣态Pb吸收效果较好,但有机结合态Pb可能会抑制芦苇根部对于Pb元素的吸收,离子态的Pb可能会抑制菖蒲根部对其的吸收。     

环渤海芦苇湿地沉积物重金属污染评价

滨海湿地位于陆地和海洋交错处的关键带,对污染物的迁移和转化具有十分重要的调控作用。为了解环渤海湿地沉积物中重金属的污染现状及潜在生态风险,文章选取环渤海11个主要芦苇湿地表层(0～20 cm)沉积物为研究对象,对其中Pb、Cr、Ni、Cu、Zn、Cd6种重金属的含量进行分析,并采用多种方法对重金属潜在来源和生态风险进行解析和评价。结果表明,环渤海芦苇湿地沉积物中Pb、Cr、Ni、Cu、Zn、Cd 6种重金属的平均含量分别为(17.92±5.81)、(50.29±20.50)、(31.53±9.71)、(25.37±4.29)、(80.13±15.11)、(0.92±0.54) mg/kg,其中,辽河三角洲湿地Pb、Cd含量最高,黄河三角洲湿地Cu、Ni、Cr含量最高,七里海湿地Zn含量最高。内梅罗综合污染指数法、地累积指数法和单因子潜在生态危害指数法的结果都表明Cd在环渤海湿地污染较严重,其他重金属污染程度较低。同时,辽河三角洲湿地和黄河三角洲湿地由于存在油田采油活动和湿地水产养殖,并且沉积物p H相对较低,是引起该地区重金属污染水平明显高于渤海湾滨海湿地的原因。因此,环渤海芦苇湿地,...     

复合人工湿地系统对重金属的去除研究

水资源的日益短缺是当今世界的主要难题,这一问题在很大程度上限制了人类社会的可持续发展,因此在注重节约用水的同时,加大对污染水的治理至关重要。随着工业的发展,污水成分逐渐复杂,传统的工艺已不能满足去除此类污染物的需求,尤其是重金属污染、石油污染等。人工湿地最为一种原位污水净化系统,有投资小、能耗低等优点。大量研究表明湿地系统对重金属工业废水的去除有较好的作用。人工湿地系统通过基质、植物、微生物对重金属进行去除。该文研究5种由水平潜流、垂直潜流、表面流3种不同工艺组合成的复合人工湿地系统对Cd、Cr、Cu、Pb、Zn的去除效果。结果表明:系列1~系列4复合型人工湿地对5中重金属都有去除效果。系列5除对Cu和Zn有显著释放现象外对Cd、Cr、Pb也有一定的去除效果。垂直潜流人工湿地对Cd、Cr、Pb的去除效果好于水平潜流和表面流人工湿地;多级复合型人工湿地对Cd、Cr、Pb的去除效果好于单级人工湿地;垂直潜流和水平潜流人工湿地对Cu的去除差异不大,垂直潜流人工湿地对Zn的去除效果优于水平潜流人工湿地。通过本研究结果,针对不同种类的重金属污染可对人工湿地系统的建设提供理论指导。     

巢湖塘西河河口湿地重金属污染风险不确定性评价

基于污染风险评价系统多种不确定性共存的特点,采用盲数描述和表征重金属污染风险评价模型的各项参数,在对采自巢湖塘西河河口湿地24个表层沉积物柱状样中Cu,Zn,Pb,Cd和Cr等指标分析测试的基础上,采用Matlab工具软件编制的潜在生态风险指数盲数评价模型程序,对巢湖塘西河河口湿地重金属污染风险进行定量评估. 结果表明:巢湖塘西河河口湿地处于中等污染至较高污染状态,其相应的可信度分别为0.589和0.411;潜在生态风险等级属较低至中等水平,其相应可信度分别为0.755和0.245. 5种重金属污染程度排序依次为Cu＞Cd＞Zn＞Pb＞Cr;潜在生态风险水平排序依次为Cd＞Cu＞Pb＞Cr＞Zn.      

重金属污染河流生态修复区挺水植物对重金属的吸收特性

为了分析比较滇东南选矿区重金属污染河流——小白河生态修复区所种植芦苇和香蒲对重金属的吸收及生态修复效果差异,于2015年4月在小白河西岸野生植物区及东岸生态修复区采集土壤及植物样品,对样品进行烘干、消解,使用电感耦合等离子体发射光谱法测定样品中铅（Pb）、锌（Zn）、铬（Cr）和镍（Ni）这4种重金属的含量,使用原子荧光光谱法测定样品中砷（As）的含量.结果表明:①小白河东岸生态修复区湿地底泥中As和Zn污染最为严重,但东岸底泥中各重金属含量已明显低于西岸,其中芦苇种植区底泥中w（As）和w（Ni）较西岸分别降低了38.82%和50.53%,香蒲种植区底泥中w（As）和w（Ni）较西岸分别降低了13.54%和21.95%.②芦苇对As、Pb、Zn和Pb、Cr以及Cr、Ni这3组重金属的吸收存在显著的协同作用,香蒲对重金属吸收的协同作用表现在As、Zn、Ni和Pb、Cr这2组重金属中,这种重金属吸收协同作用在芦苇中更明显.③芦苇对Cr的生物富集系数（BCF）较高,对Cr的转运系数（TF）为0.80,属于富集型耐受策略,芦苇对Zn和Ni属于根部囤积型耐受策略;香蒲对Pb、Zn、Ni、Cr这4种重金属的BCF较大,TF均接近1,属于富集型耐受策略,对As属于根部囤积型耐受策略.研究显示,芦苇可作为重金属污染河流生态修复区的先锋植物,香蒲的重金属生物富集效率较高,将重金属富集于地上部的能力较强,可考虑将植物分区种植的模式改为间作种植,并定期收割香蒲地上部,以使生态修复区具有更好的重金属修复效果.      

淇澳岛红树林生态系统中重金属含量相关性

采集珠海淇澳岛北部大围湾的红树林区潮间带沉积物和植物组织样品若干,测定各样品中Cu、Zn、Cd和Pb的含量,四种重金属含量在各沉积物中、各植物组织中以及沉积物和植物组织之间的相关性。研究表明,沉积物中Pb和Zn含量呈极强正相关,Pb、Zn与Cd含量之间呈强正相关,其他各类重金属之间的相关性不显著。四种重金属与沉积物颗粒形态相关性均不显著。红树植物各组织对四种重金属的富集系数范围为0.001~0.72,0.006~0.39,0.053~1.97和0.004~0.24,富集能力与林龄正相关,其中对Zn、Cd和Pb的富集系数与土壤中含量呈负相关,表明在过高重金属污染胁迫的环境中红树植物有自行降低富集能力以避免被伤害的趋势。     

纳污湿地表层沉积物中重金属形态研究

采用Tessier法提取了武河湿地表层沉积物中重金属元素Cu、Zn、Pb、Hg、Cd,对其形态分布特征和相关性进行了分析,并利用潜在生态风险指数法对武河湿地表层沉积物中重金属污染进行了综合性评价分析,结果表明:各元素主要以残渣态形式存在,其平均含量均在80%以上;Hg活性态含量为0.098 mg/kg,低于环境背景值,环境危害轻微;相关分析表明碳酸盐结合态的Cu、Zn、Pb、Cd的污染源相似,有机结合态的Cu、Zn、Cd污染源相近,残渣态Cu、Zn、Pb污染源相近,残渣态Pb和Cd污染源相似或相近;各重金属元素迁移能力表现为Cd(5.40)Pb(5.22)Zn(2.31)Cu(0.94);各元素的潜在生态风险表现为CdCuZnPb,且Cd、Pb属于生物毒性显著的元素,对于其引起的污染更应该加倍重视。     

亚热带河网湿地沉积物重金属分布及风险评价

采用原子吸收光谱法测定了中国南亚热带典型河网湿地(海珠湿地)水域环境表层沉积物中重金属Cu、Zn、Pb、Cd、Ni、Cr、Fe、Mn的含量,通过聚类分析和相关分析方法探讨其重金属的空间分布及来源特征,利用Hakanson生态风险评价法和基于一致性的沉积物质量基准法比较评价该区域重金属污染生态风险。结果显示,海珠湿地水域表层沉积物各重金属含量范围分别为:Cd(0.11~4.37 mg/kg)、Pb(54.9~156.0 mg/kg)、Cr(40.7~225.5 mg/kg)、Cu(34.2~244.9 mg/kg)、Ni(30.9~133.2 mg/kg)、Zn(134.8~669.7 mg/kg)、Fe(2.5%~4.2%)及Mn(0.04%~0.06%),均不同程度地超过区域背景值,且呈狭窄水面向宽阔水面区域递减的空间变化趋势。除Cd在丰水期显著高于枯水期外,其他金属的含量季节差异不显著。各重金属来源及变化趋势表现为两大类群:Cu、Zn、Pb、Cd、Ni和Cr之间具有显著的相关性,可能以人类活动污染为主;而Fe和Mn之间具有显著的相关性,以地壳自然来源为主。海珠湿地总体重金属生态风险较高,应对该区域重金属含量及水生生物状况进行跟踪监测,以维护水域生态系统的健康与平衡。     

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.