城市湿地生态系统保护的现状与思考

湿地是人类生态系统的重要组成部分,而城市湿地更是生态系统保护不可或缺的一环,本文通过对湿地的功能、生态学意义,以及城市湿地生态系统保护的现状的阐述,对城市湿地生态系统保护的有效措施———城市湿地公园的建设原则和生态保护对策进行了初步探讨。     

滨海湿地生态修复研究进展

滨海湿地是地球上一类重要的生态系统,它为人类社会提供了众多的生态服务功能。受人类活动和气候变化的影响,大量滨海湿地退化甚至消失。针对滨海湿地生态系统面临的严峻问题,国内外学者开展了大量湿地生态修复方面的研究与实践工作。本文综述了基于微生物和植物的滨海湿地有机、无机污染生态修复研究进展,探讨了这些技术措施存在的问题与不足,并对滨海湿地生态修复技术的发展趋势做出了展望。     

我国人工湿地污水处理系统的现状探析及展望

人工湿地是一种生态污水处理工程系统,20世纪80年代后期被引入中国,随后其数量快速增长。人工湿地与传统污水处理厂相比,投资低、成本低、效率高,具有多重生态服务功能。本文分析了人工湿地污水处理效率、生态服务功能、湿地植物的再资源化利用以及人工湿地在我国发展的驱动力机制,提出了该技术的局限性、发展趋势及面临挑战。我国人工湿地污水处理系统的发展,应充分发挥政府"自上而下"管理和社会"自下而上"参与的双方面作用,同时加强对民众的科普宣传工作。     

湿地资源研究进展与发展方向

湿地资源研究是对湿地资源类型与特征、数量与质量进行调查和评估,揭示湿地资源各要素间的相互作用以及人类活动对湿地资源的影响,协调湿地资源保护与合理利用关系。论文分析了湿地资源研究的现状与战略需求;国内外在湿地资源监测,湿地资源功能评价,湿地水资源与生态恢复,湿地生物资源保护,湿地与全球变化,城市湿地与城市湿地公园,湿地生态旅游,典型区域湿地动态演变与人类活动影响,以及新技术和新方法在湿地研究中的应用等领域最新进展。并结合国内外湿地资源研究发展趋势,指出了未来湿地资源研究发展方向。     

湿地景观格局演变与生态安全响应——以福州市浦下洲区域及周边湿地为例

利用航空卫星图片与野外调查数据对福州浦下洲区域及周边景观格局动态变化及其生态安全响应过程进行研究.结果表明:浦下洲区域及周边湿地近20年来人类干扰作用持续加强,各种湿地景观类型破碎化程度加大;景观组分的变化过程对湿地生态系统的功能和稳定性产生了重要影响,大部分湿地生态功能已经丧失.     

大庆市草原和湖泊生态保护建设研究

通过对大庆草甸草原和湖泊湿地发生发展自然生态过程的分析,以大庆生态环境的整体性特征为基础,提出草甸草原是大庆生态环境的基础,湖泊湿地是大庆生态环境的特色.以保护和恢复为主巩固草原生态基础地位,以生态重建为主突出湖泊湿地特色.对生态功能正常发挥的草原,以生态保护为主,对生态功能退化草原,以生态恢复为主.对油田生产区的草原,重视生态功能和景观效应.以生态重建为主突出湖泊湿地特色,通过地表水结构的调整增加生态系统的活力和生态服务功能.草甸草原和湖泊湿地的保护与利用要扬长补短、协同并进.     

江汉平原典型湿地演化特征及其控制因素研究

江汉平原典型湿地具有重要的生态价值和经济价值.为研究江汉平原湿地演化特征及其控制因素,解译了 2000-2018年研究区不同时期的遥感影像,计算了江汉平原湿地以及区内典型湿地(洪湖湿地、长湖湿地)面积的变化,并通过季节性肯达尔检验法分析了湿地面积随时间的变化特征以及降水量、地表水水位、地下水水位的动态变化和人类活动对江...     

城市湿地的生态环境保护问题探讨--以哈尔滨市为例

城市湿地存在于城市区域内或城市边缘地带,与城市的形成和发展息息相关,其生态功能不同于自然湿地。近年来,由于受到人类活动的干扰,城市湿地面临湿地面积缩小、生态系统变脆弱、水体环境受污染、生物多样性被破坏等生态环境保护问题。在调研哈尔滨市城市湿地公园现状的基础上,以哈尔滨市为例,阐述城市湿地的作用和价值,归纳分析了城市湿地主要的生态环境保护问题,提出了哈尔滨市开发建设中加强城市湿地生态环境保护的建议。     

湿地污水处理机理的研究

作为全球三大生态系统之一,湿地有着巨大的生态、社会和经济效益。它不仅为人类的生产、生活提供多种资源,而且具有巨大的环境功能和效益,被誉为“地球之肾”。本文针对湿地在污水处理中应用作了一些探讨,介绍人工湿地分类、处理污水的机理、利用人工湿地处理污水的一般工艺流程以及人工湿地用作处理污水时存在的问题。     

基于水动力过程的湿地生态补水优化机制：以北京汉石桥湿地为例

湿地具有涵养水源等重要生态服务功能,但在人类活动与气候变化的多重胁迫下出现萎缩与退化,其中湿地补给水量不足是其主要生态问题之一。随着跨区域、跨流域调水工程的实施运行,生态补水目前已成为湿地修复与水资源配置的关键技术组成。因此,关注多水源补给湿地的补水路径优化,基于湿地补水水动力过程提出了生态补水方式的优化方案。2021年在潮白河流域全线通水的背景下,以北京市仅存的大型芦苇沼泽湿地——汉石桥湿地为案例区,构建了潮白河流域SWAT模型模拟径流变化规律,利用MIKE21模型模拟湿地补水水量-水动力耦合过程,比较了6种湿地补水情景的水动力变化特征。结果表明：汉石桥湿地内部水系连通受阻造成的湿地南部与北部分隔是限制生态补水效率的主要瓶颈,湿地南北区多流路同时补水,以及改造湿地水文连通结构是改善补水水动力条件,提升生态补水效应的优化方案。该研究结论可为湿地的长期管理和生态修复提供参考,有利于首都城市生态水系建设。     

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.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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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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.     

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.