不同浓度磷胁迫对高原湿地植物黑藻根系分泌物的影响

采用营养液水培方式,研究湿地典型沉水植物黑藻(Hydrilla verticillata)根系分泌物在不同浓度磷胁迫下的适应机制,以期为高原湿地污染修复的根际调控措施提供科学依据。结果表明,黑藻根系分泌物主要有烷烃类、酯类、酸类、硫类、胺类、醇类、醛类、酮类等化合物,不同浓度磷胁迫下,黑藻根系分泌物的种类和对应的相对含量差异较大,表明黑藻会主动通过根系自我调控分泌物的成分和数量来适应环境。无磷胁迫(TP=0mg/L)下,黑藻根系分泌物主要为硅烷、环庚硅氧烷,占比分别为16.24%、14.61%,而在不同浓度的磷胁迫后,有机酸总占比明显增加,各处理邻苯二甲酸的占比均为最高,说明黑藻根系增加邻苯二甲酸的分泌是响应环境磷胁迫的一种重要机制。此外,磷胁迫对环庚硅氧烷、苯二羧酸、邻苯二甲酸二异辛酯、1-甲基吡咯烷酮、二苯砜等也有显著影响,这些根系分泌物对于黑藻适应外界磷环境同样具有重要的作用。     

5种湿地沉水植物对模拟污水厂尾水的深度处理

选取四季常青苦草、普通苦草、黑藻、狐尾藻和马来眼子菜等5种沉水植物构建表面流人工湿地系统,观察不同沉水植物品种对模拟污水厂尾水中主要污染物的去除效果,筛选出具有最佳去污效果的沉水植物,为优化沉水植物表面流人工湿地系统的处理效果提供理论依据。结果表明:沉水植物表面流湿地系统和无植物表面流湿地系统对各污染物的去除效果均呈现出随着实验时间的延长先波动变化后逐渐趋于稳定的规律。四季常青苦草、黑藻和狐尾藻湿地系统出水COD、TP浓度均低于10 mg·L~(-1)、0.1 mg·L~(-1),分别达到了《地表水环境质量标准》(GB 3838~(-2)002)Ⅰ和Ⅱ类水标准。除马来眼子菜外,其余4种沉水植物对主要污染物的净化效果存在较大差异,以四季常青苦草的综合净化效果最好,出水COD、TP、NH+4-N、NO-3-N和TN的平均浓度分别为36.83、0.269、1.17、0.563和3.31 mg·L~(-1),平均去除率分别达到41.32%、72.77%、84.29%、79.28%和76.72%。黑藻次之,接着是狐尾藻,而普通苦草的去污效果较差。综合考虑其对模拟城市污水处理厂尾水的深度处理效率,宜选择四季常青苦草作为表面流人工湿地的优选沉水植物。     

人工湿地-沉水植物塘组合系统治理村镇污染水体

采用人工湿地-沉水植物塘组合系统在不同水力负荷(200、500、1 000mm/d)条件下对村镇污染水体净化效果进行研究。结果表明:在不同水力负荷和污染负荷下,组合系统整体运行稳定、耐负荷能力强、去除效果良好;出水COD达到《地表水环境质量标准》(GB 3838—2002)的Ⅲ类标准,出水总磷达到GB 3838—2002的Ⅴ类标准,出水总氮达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准,出水氨氮达到GB 18918—2002的一级B标准。除溶解性正磷酸盐以外,组合系统对污染物的去除效果均随着水力负荷的增加整体呈现出下降趋势,低水力负荷去除效果最优。沉水植物塘在氮、磷去除效果上优于人工湿地,而人工湿地在COD去除效果上则优于沉水植物塘。     

盐胁迫对3种沉水植物生物学指标及叶片中丙二醛含量的影响

以沉水植物苦草、轮叶黑藻、狐尾藻为研究对象,分别研究了在不同盐度下3种沉水植物的生物学指标和生理状况,以期为沿海地区水系沉水植物构建提供依据。结果表明,在0.05mol/L盐度下轮叶黑藻、苦草出现生长抑制,株高、鲜质量下降,叶片中丙二醛含量增加,单株叶片面积减小,而狐尾藻在0.05mol/L盐度下生长良好,0.08mol/L盐度下出现株高、鲜质量下降,叶片中丙二醛含量增高的现象。因此,推荐盐度在0.05mol/L以下的水体,可以建植苦草和轮叶黑藻,盐度不高于0.08mol/L的水体可以建植狐尾藻。盐胁迫下沉水植物会表现为一定的抗逆性,会通过单株叶片面积减小、增加根冠比、叶片肉质化等措施来减少水分流失和保证机体的正常生理功能,但超过一定的阀值,抗逆性会减弱,导致沉水植物出现生长抑制或者死亡现象。在有一定盐度的水体进行沉水植物建植恢复,该沉水植物能够耐受的盐度高于水体的盐度,是保证沉水植物成活的基本前提。     

砷胁迫对不同物候期香蒲根系分泌物的影响

为探究典型湿地挺水植物香蒲(Typha angustifolia L.)在砷(As)污染生境中不同物候期的根系分泌物变化特征,测定并分析了A s胁迫下的香蒲根系分泌物构成.结果表明:(1)香蒲根系分泌物主要包括烃类、酚类、生物碱类,枯黄期仅有这3类分泌物,幼苗期还有少量唑类,花果期根系分泌物种类最丰富,出现了特有的有机...     

黑藻根际对沉积物中氨氧化细菌和古菌的影响

氨氧化反应对水生态系统氮循环和氮的去除有重要作用,沉水植物通过根系泌氧促进沉积物中硝化反应并对氨氧化细菌和古菌的分布产生影响。本研究以轮叶黑藻为实验对象,利用微电极研究沉积物-水界面的溶解氧变化,研究了黑藻根系对沉积物中氨氧化细菌和古菌数量的影响。结果表明,黑藻通过根系泌氧增加沉积物-水界面的溶解氧量和表层沉积物有氧层厚度,有氧层厚度增加了3 mm以上;种植黑藻后,根际沉积物中氨氧化细菌数量逐渐增加,氨氧化古菌数量前30天增加随后减少,氨氧化细菌与氨氧化古菌amoA基因拷贝数的比值由0.51增加到6.75,说明黑藻根际沉积物更适宜氨氧化细菌的生存。     

模拟升温对沉水植物生长及磷迁移的影响

通过构建2组人工配置沉水植物群落,以增温5℃增温组模拟微宇宙环境暖化,通过沉水植物的存活率、相对生长速率、优势度、多样性指数等来研究暖化对沉水植物生长及物种多样性的影响;同时通过上覆水各形态磷、沉积物各形态磷的测定来研究气候暖化条件下2种人工配置沉水植物群落对磷迁移的影响。研究表明,极端高温不利于人工配置Ⅱ(金鱼藻占60%,黑藻和菹草各占20%)的生长,但秋冬季暖化可延长沉水植物的生长期,总体来看其相对生长速率、存活率未受影响。气候暖化降低了物种多样性,不利于沉水植物群落稳定。对于磷迁移,钙磷(Ca-P)在增温条件下高于未增温条件下。     

模拟人工湿地中基质酶对PhACs的动态响应

基质酶是催化土壤生物化学反应的重要催化剂,其对有机污染物具有高度敏感性。实验测定了5座人工湿地(CWs)反应器中过氧化氢酶、脱氢酶和脲酶活性的动态变化及其与进水医药活性物质(PhACs)浓度、湿地植物的关系。结果显示:种植植物反应器3种基质酶的活性均高于未种植植物的反应器;随培养时间增长过氧化氢酶的活性逐渐提高,在培养150 d后达到最高;脱氢酶和脲酶的活性随培养时间增长先升高后降低,分别于120 d和90 d时达到最高;不同基质酶对不同PhACs浓度响应不同,脲酶活性均表现为被抑制,而脱氢酶和过氧化氢酶活性在低PhACs浓度时被激活,在高PhACs浓度时被抑制。为CWs应用于去除水环境中存在的PhACs类污染物提供参考。     

3种负荷对模拟垂直流人工湿地去除氮、磷效果的影响

为探讨水力负荷、有机负荷和悬浮物固体负荷对垂直流人工湿地基质去除氮、磷效果的影响,采用了人工土柱模拟实验的方法,对不同数值的水力负荷、有机负荷(COD)和悬浮固体负荷单因素影响条件下垂直流人工湿地出水中TN、TP的浓度进行了监测。实验结果表明,在3种负荷单一因素影响条件下,垂直流人工湿地处理出水中TN、TP的浓度均随着负荷的增加而增加,即降低水力负荷、有机负荷、悬浮固体负荷均有利于降低垂直流人工湿地处理出水中TN、TP的浓度。当水力负荷为50 cm/d,垂直流人工湿地TP的去除率较高,达到71.52%;当有机负荷为50 g/(m2·d),TN的平均去除率较高,达到41.84%;当悬浮固体负荷为75 g/(m2·d),TP的平均去除率较高,达到92.13%。因此,在水力负荷实验中,当水力负荷为50 cm/d,垂直流人工湿地对氮、磷去除效果较佳;在悬浮固体实验中,当悬浮固体负荷为75 g/m2·d,垂直流人工湿地对氮、磷去除效果较好;在有机负荷实验中,当有机负荷(COD)为50 g/(m2·d),垂直流人工湿地对氮、磷去除效果较好。     

湿地系统对痕量有机物的去除效果分析

以处理工业污水和生活污水的表流湿地系统为研究对象,利用气相色谱/质谱联用仪(GC/MS)检测其进、出水中的16种多环芳烃和6种邻苯二甲酸酯浓度,分析进、出水中的典型污染物并对比其浓度差异,以确定湿地系统的处理效果。结果表明:湿地系统工业污水的典型污染物为萘、菲、邻苯二甲酸二丁酯、邻苯二甲酸二(2-乙基己基)酯,质量浓度为122.62~760.61ng/L;湿地系统生活污水的典型污染物为萘、蒽、菲、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯、邻苯二甲酸二(2-乙基己基)酯,质量浓度为280.21~7 998.06ng/L。湿地系统出水的典型污染物为萘、菲、邻苯二甲酸二丁酯、邻苯二甲酸二(2-乙基己基)酯,质量浓度为42.00~1 430.74ng/L。湿地系统对痕量有机物有较强的去除效果,各污染物的去除率为10%~99%,其中有19种污染物的去除率在70%以上。     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.