武河湿地碳氮净化长效性及其内源分布与释放

实验以运行10年的山东武河人工湿地为例,按照水流方向采集原位水样和柱状沉积物样,对其碳氮的净化能力和沉积物碳氮的分布特征及其内源释放风险进行了分析。结果表明:武河人工湿地稳定运行10年后,对水体中的氮仍具有一定净化能力,TN去除率为35%左右,但对COD基本没有净化效果,出水COD值达70.73 mg/L,水体NH_3-N、NO_3~--N、TN和COD浓度均未能达到地表水Ⅳ类水质的设计目标;武河人工湿地沉积物TN含量较高,表层20 cm平均含量高达3 742.95 mg/kg,为重度污染,NH_3-N平均含量为303.06 mg/kg,占TN的比例为8.09%,NO_3~--N平均含量极低,仅为5.19 mg/kg,沉积物氮主要以有机氮(ON)的形式存在;垂向上,沉积物TN含量为2 755～4 250 mg/kg之间,总体上表现为随深度增加略微减少的趋势,外源氮负荷对沉积物TN起决定作用。静态培养实验显示,武河湿地各点位沉积物同上覆水体NH_3-N、TN和COD的交换速率差异较大,但均以吸附为主,4个点位对COD的吸附速率分别为2 921.25、3220.85、3 629.70和5 135.91 mg/(m~2·d),人工湿地沉积物对水体NH_3-N、TN和COD具有较好的吸附能力。湿地沉积物有机质(LOI)含量为4.57%～11.9%,相关性分析表明,沉积物LOI与NH_3-N、NO_3~--N、TN的含量均呈显著正相关,相关系数分别为0.703、0.748和0.700,沉积物氮负荷与有机质来源相对一致。     

典型再生水人工湿地净化系统水质时空变异研究——以北京市奥林匹克森林公园人工湿地为例

选取奥林匹克森林公园人工湿地作为典型再生水补水人工湿地净化系统进行水质数据检测,应用模糊综合评价法综合评估各净化单元的水体污染状况,采用综合判别分析和Spearman相关分析阐释影响各净化单元时空变异的水环境要素,并通过因子分析识别不同时间段污染源的种类和组成.结果表明,奥林匹克森林公园人工湿地净化系统水质状况较好,符合人体非直接接触的景观用水国家标准.人工湿地各净化单元时空区间污染程度不同:季节尺度上,秋季污染更为严重;空间尺度上,主湖区、混合氧化塘区污染最为严重.CODMn、NO-3-N、ORP、TN 4项指标即可完全表征水质的季节差异(91.8%),应适当加大监测力度;Chl-a、CODMn、DO、pH 4项指标用于表征空间差异(55.1%),较低的判别正确率暗示了各功能区间类似的污染状况.不同时空区间污染源种类和组成存在差异性:水体的内源杂质是各季度影响水质的主要因子,春季有机污染最为严重,夏季则转为氮、磷等营养物质污染,秋季水体则更易受富营养化的威胁;再生水区水体污染的主要影响因子为氮、磷等营养盐类,其余功能区水体主要影响因子仍为内源杂质.增强水体流通力,缩短水力停留时间,能够有效减弱富营养盐类和有机污染物的影响.     

朱庄水库水体氮循环系统对水质的影响分析

通过朱庄水库流域污染源调查,氮污染是朱庄水库水体的主要污染物.结合对水库水体氮循环发生机理进行分析,在分析时,考虑水温、溶解氧和酸碱度等环境因子对氮循环的影响.硝化作用对减少氨氮和亚硝酸盐氮两种污染物起积极作用,反硝化作用受环境因子限制,对硝酸盐氮的降解并不明显.通过对朱庄水库氮循环对水质的影响分析,为制定水库供水方案提供科学依据.     

纳污湿地上覆水中重金属的监测及评价

以武河湿地为研究区域采集上覆水水样,采用ICP-AES法测定湿地水体中重金属的含量,参照有关标准用水质标准级别法对水中重金属污染情况进行了评价。结果表明:武河湿地中重金属Hg污染十分严重,各采样点均有分布且水质属劣Ⅴ类。重金属元素Cd污染并不严重,总体水质较好。重金属元素As、Cr、Cu、Pb在武河湿地中污染较轻近乎无污染,水质为Ⅰ类。由于重金属Hg的污染十分严重所以研究区内综合质量等级在4以上,水质为Ⅴ类和劣Ⅴ类,污染严重。     

北京市潮白河再生水补水河段水质时空变异

城市河道是城市再生水利用的主要载体,而人工湿地是城市再生水河道补水前主要的水质净化方式.为了解再生水补水与人工湿地对再生水补水段水质的影响,选取北京市潮白河再生水补水河段作为研究对象,利用聚类分析、判别分析及因子分析等方法对不同季节水体的水质情况进行分析.结果表明:研究区内水体氮磷污染严重,其中TN污染表现为NO₃--N、NO₂--N和NH₄+-N的混合型污染.聚类分析结果表明,水质在季节尺度上表现为丰水期（6-9月）和枯水期（2月、3月、5月和12月）两大类;在空间尺度上受再生水补水和湿地净化的影响表现为显著的空间差异性.判别分析结果表明,再生水补给对河道水质的影响无显著季节差异,湿地净化功能在丰水期和枯水期差异较大且丰水期湿地的净化效果最为明显.因子分析结果表明,再生水作为城市河道的补充水源,一方面对河道中的F-、Chl-a等起到稀释作用,另一方面使得水体中的N、P及离子含量增加;丰水期湿地的净化作用使水体中氮磷等有机营养物质含量及ρ（TDS）等显著降低.      

百花湖周边城市近郊小流域氮、磷输出时空特征

识别主要污染物与污染源对于贵阳周边流域水质的控制与管理具有重要的现实意义.于2010年7月~2011年4月连续进行的野外观测实验,研究了贵阳市重要的水源地百花湖水库周边的麦西河小流域氮、磷流失浓度特征,以便为贵阳市城市近郊小流域面源污染治理提供参考.流域有各种源和汇的存在,导致研究流域在不同时间,从上游到下游,各采样点氮输出变化较大.各采样点水体的不同形态氮含量和磷含量随时间变化总体上仍呈现出一定的规律,总氮、硝氮以2010年7月较高,氨氮、亚硝氮和总磷以2010年10月和12月较高.从上游到下游,各采样点水体中不同形态氮含量和磷含量差异减少.在流域下游的河口处,TN含量由3.297 mg·L-1下降为2.793 mg·L-1,TP从0.136 mg·L-1下降到0.098 mg·L-1,但与中游比较,变化不明显,氨氮含量还有所上升.从流域氮、磷输出时空变化特征来看,氮素特别是氨氮和硝态氮通过河道径流途径进入百花湖的风险较高.研究结果可为百花湖周边小流域氮、磷流失治理做参考.     

城区景观水体生态重建中水生植物和光催化反应器的应用

城区景观水体是居民观赏、休闲、及娱乐的场所,对美化城市人居环境、净化空气、调节区域温度等具有积极作用。由于面源污染等因素,目前中国城区景观水体氮、磷营养盐含量高,藻类泛滥,水生生态系统单一,大多呈现富营养化状态。本文以广州市某景观湖泊为案例,利用低扬程水泵推流,使景观水体形成环流。部分环流经过固载型TiO2光催化反应器、人工湿地处理,再和环流水体汇合。研究表明,光催化反应器具有很强的杀藻能力,同时减少了藻类在后续人工湿地的沉积,提高了人工湿地对有机物、氮、磷等污染物的去除效果。通过近二年的研究和运行维护,有效地遏制了浮游植物的泛滥,景观水体的水质得到改善,水体生态系统多样性得到一定程度的恢复。     

垂直潜流人工湿地低温净化效果及其与微生物作用关系

人工湿地净化过程受基质、微生物及植物的多重作用,但有关湿地系统水质净化效果与微生物之间的关联及响应机制的认识较为匮乏.本文针对垂直潜流人工湿地,分析了其低温条件下水质净化效果,通过16S rDNA扩增子测序技术,在OTU水平上利用微生物丰度聚类热图和基于Bray-Curtis距离的NMDS分析,揭示了湿地基质微生物群落结构的时空变化及其与主要水质指标之间的相互作用关系.结果表明,湿地对TN、COD的去除效果较好,但对TP的去除效果不佳.基质微生物群落时空变化显著,与湿地净化效果密切相关,革兰氏阴性菌门类众多和假单胞菌属相对丰度较低,分别是TN去除效果较好和TP去除效果不佳的重要原因.COD、DO是影响微生物群落的主要因子,而氮含量在一定程度上影响脱氮微生物的活跃度.基质微生物在湿地运行2周后,对污染物去除的介导作用稳定,建议设立这一关键时间点,并辅以菌群、碳源投入等措施,提升湿地的净化效果.     

西溪湿地底泥氮、磷和有机质含量竖向分布规律

利用特制的取样器从西溪湿地钻取连续完整的底泥试样,对不同深度底泥中总氮(TN)、总磷(TP)和有机质(OM)含量进行测试;通过TN、TP、OM在表层底泥、底泥孔隙水和上覆水体中含量变化的分析结果,并运用有机指数法对该湿地底泥的污染程度进行了评价.结果表明,该湿地60cm深度以内的底泥为轻度~中度污染,属于活性层;埋深大于60cm的底泥未受污染或者污染较轻,属于相对稳定层;TN、TP、OM在垂向上的变化呈显著相关关系.TN、TP在底泥孔隙水中的含量显著高于在上覆水体中的含量;由于存在浓度梯度,底泥孔隙水中的氮、磷及其他有机污染物会释放到上覆水体中去,只实施换水处理难以根除湿地水体富营养化的问题.对作为内污染源的底泥,疏浚应是一种更有效的治理措施,60cm活性层深度可作为该湿地疏浚参考深度.     

人工湿地植物水体净化效能研究进展

通过检索近20年来人工湿地植物在净化水质方面代表性文献,筛选出50种常见人工湿地植物,包括水生植物(挺水植物、浮水植物及浮叶植物、沉水植物)、湿生植物、旱生植物,对该50种常见植物的净化效能进行分析比较;指出湿地植物在净化水体时可能受物种、环境因子、种类配置模式三方面的影响;提出未来人工湿地植物选择应用方面发展方向为:应进一步扩大其种类的选择范围,加强探究维持其生长代谢的机理,加强与微生物的耦合作用完成水体污染物净化的效能研究,根据不同人工湿地和水体污染物类型进行配置等4个方面。     

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.     

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.     

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.     

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.     

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.     

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.