连续/间歇曝气改良一体化氧化沟处理生活污水对比试验研究

为了提高改良一体化氧化沟(MIOD)的除磷效率和降低运行能耗,分别对连续曝气和间歇曝气(曝气1 h/停曝1 h)2种运行方式下系统处理生活污水的效果进行了对比试验研究.结果表明:(1)连续曝气运行方式下系统对COD、NH3-N、TP的去除率分别为85.28％、91.14％、73.09％;间歇曝气运行方式下系统对COD、...     

铁盐改性砂制备及其吸附Zn~(2+)的性能研究

通过改变石英砂表面的物理化学性质,提高石英砂的吸附效率,考察其对废水中的Zn~(2+)去除效果.以石英砂为载体,分别用反复高温加热法和反复碱性沉积法制备了三氯化铁改性砂、硝酸铁改性砂,测定2种方法制备的铁盐改性砂的表面含铁量、铁盐的酸稳定性及比表面积,并比较2种铁盐改性砂对Zn~(2+)的吸附效果.结果表明,三氯化铁改性砂、硝酸铁改性砂的比表面积分别为2.468、4.247 m~2/g,比石英砂比表面积分别提高6.910、12.612倍;在pH为中性条件下,石英砂对Zn~(2+)去除率为43%左右,三氯化铁改性砂对Zn~(2+)去除率达到70%左右,硝酸铁改性砂对Zn~(2+)去除率达到85%左右,表明铁盐改性砂对Zn~(2+)去除能力比石英砂有很大提高;铁盐改性砂对Zn~(2+)的吸附有一定容量,表面的活性中心越多,吸附能力越大;铁盐改性砂对Zn~(2+)的去除率随着pH的升高而增加,当pH>8.5时,Zn~(2+)去除率可达90%左右.     

The variability of processes involved in transgene dispersal—case studies from Brassica and related genera

Background, aim, and scope

We strive to predict consequences of genetically modified plants (GMPs) being cultivated openly in the environment, as human and animal health, biodiversity, agricultural practise and farmers’ economy could be affected. Therefore, it is unfortunate that the risk assessment of GMPs is burdened by uncertainty. One of the reasons for the uncertainty is that the GMPs are interacting with the ecosystems at the release site thereby creating variability. This variability, e.g. in gene flow, makes consequence analysis difficult. The review illustrates the great uncertainty of results from gene-flow analysis.

Main features

Many independent experiments were performed on the individual processes in gene flow. The results comprise information both from laboratory, growth chambers and field trials, and they were generated using molecular or phenotypic markers and analysis of fitness parameters. Monitoring of the extent of spontaneous introgression in natural populations was also performed. Modelling was used as an additional tool to identify key parameters in gene flow.

Results

The GM plant may affect the environment directly or indirectly by dispersal of the transgene. Magnitude of the transgene dispersal will depend on the GM crop, the agricultural practise and the environment of the release site. From case-to-case these three factors provide a variability that is reflected in widely different likelihoods of transgene dispersal and fitness of introgressed plants. In the present review, this is illustrated through a bunch of examples mostly from our own research on oilseed rape, Brassica napus. In the Brassica cases, the variability affected all five main steps in the process of gene dispersal. The modelling performed suggests that in Brassica, differences in fitness among plant genome classes could be a dominant factor in the establishment and survival of introgressed populations.

Discussion

Up to now, experimental analyses have mainly focused on studying the many individual processes of gene flow. This can be criticised, as these experiments are normally carried out in widely different environments and with different genotypes, and thus providing bits and pieces difficult to assemble. Only few gene-flow studies have been performed in natural populations and over several plant generations, though this could give a more coherent and holistic view.

Conclusion

The variability inherent in the processes of gene flow in Brassica is apparent and remedies are wished for. One possibility is to expose the study species to additional experiments and monitoring, but this is costly and will likely not cover all possible scenarios. Another remedy is modelling gene flow. Modelling is a valuable tool in identifying key factors in the gene-flow process for which more knowledge is needed, and identifying parameters and processes which are relatively insensitive to change and therefore require less attention in future collections of data. But the interdependence between models and experimental data is extensive, as models depend on experimental data for their development or testing.

Recommendations

More and more transgenic varieties are being grown worldwide harbouring genes that might potentially affect the environment (e.g. drought tolerance, salt tolerance, disease tolerance, pharmaceutical genes). This calls for a thorough risk assessment. However, in Brassica, the limited and uncertain knowledge on gene flow is an obstacle to this. Modelling of gene flow should be optimised, and modelling outputs verified in targeted field studies and at the landscape level. Last but not least, it is important to remember that transgene flow in itself is not necessarily a thread, but it is the consequences of gene flow that may jeopardise the ecosystems and the agricultural production. This emphasises the importance of consequence analysis of genetically modified plants.     

原位柱撑改性膨润土在微污染饮用水除磷中的应用研究

利用Al3+离子较易水解聚合的性质,微波辅助合成了keggin Al₁₃原位柱撑改性膨润土(PMCs),并探究了其对微污染饮用水中磷元素的去除作用,研究表明,PMCs对磷的混凝和去除作用优于原土、工业 PAC和传统的柱撑改性膨润土(CPMCs);影响除磷效果的主要因素有：搅拌时间、搅拌速度、水样的pH值以及初始浓度等,其最佳除磷条件是：在500 mL 10 mg/L含磷水样中加入1.5 g改性膨润土,搅拌速度为180 r/min,搅拌时间为5 h,水样pH为6～8。     

改性PES膜在MBR中膜阻力分析及膜污染机理研究

以聚醚砜(PES)、醋酸纤维素(CA)和纳米二氧化钛(TiO2)为膜材料,采用L-S相转化法制备共混改性PES膜。在24℃、0.2 MPa的操作条件下,制得的PES膜纯水通量为300 L/(m2.h)左右,CA改性PES膜为660 L/(m2.h)左右,TiO2改性PES膜为840 L/(m2.h)左右。通过膜生物反应器中膜阻力的测定,表明膜污染主要由浓差极化层及凝胶层引起的;通过活性污泥对膜污染机理的研究,判断出污泥的过滤过程基本符合沉积过滤定律。在MBR中运行时,改性PES膜稳定通量高于未改性膜,总阻力低于未改性膜;TiO2改性膜稳定通量高于CA改性膜,总阻力低于CA改性膜;通过扫描电镜分析,改性PES膜沉积层的厚度均比未改性膜薄,TiO2改性膜沉积层厚度小于CA改性膜,表明改性膜的抗污染性能提高了,TiO改性膜抗污染性能更优。     

区域环评中北方河流水环境容量计算方法研究

考虑北方河流枯水期流量较小,污水处理厂排水形成的流量不可忽略的实际情况,对全国地表水环境容量基于环境容量定义及基于一维模型的水环境容量计算公式进行修正;实例计算结果表明：用该方法计算的环境容量与污染物预测结果具有非常好的拟合性。文中水环境容量计算公式中相关参数的选取原则及修正公式,可为北方区域开发项目水环境剩余容量的计算提供借鉴。     

改性活性炭吸附净化黄磷尾气中的H2S

研究了以Cu²⁺离子活性溶液制备改性活性炭吸附净化黄磷尾气中H₂S的相关问题,考察了改性活性炭制备过程中的浸渍液浓度、干燥温度和焙烧温度的影响,以及温度和氧含量对吸附的影响;并对空白活性炭、改性活性炭吸附前后做SEM表征。研究结果表明,浸渍液浓度0.05 mol/L、干燥温度120℃、焙烧温度250℃为改性活性炭制备的最佳条件;吸附反应阶段较适宜的温度为95℃,氧含量为1%;结合扫描电镜初步表明,改性后的活性炭S容量增加,吸附效果明显。     

Hazard mitigation or mitigation hazard?

BACKGROUND, AIM AND SCOPE: Transgenic oilseed rape (Brassica napus L.; OSR) is estimated to be environmentally and economically problematic because volunteers and ferals occur frequently and because of its hybridisation potential with several wild and weedy species. A proposed mitigation strategy aims to reduce survival, in particular in conventional OSR crops, by coupling the transgenic target modification with a dwarfing gene to reduce competitive fitness. Our study allowed us to access potential ecological implications of this strategy. MATERIALS AND METHODS: On a large scale (>500 km(2)), we recorded phenological and population parameters of oilseed rape plants for several years in rural and urban areas of Northern Germany (Bremen and surroundings). The characterising parameter were analysed for differences between wild and cultivated plants. RESULTS: In rural areas, occurrences of feral and volunteer OSR together had an average density of 1.19 populations per square kilometre, in contrast to urban areas where we found 1.68 feral populations per square kilometre on average. Throughout the survey, the vegetation cover at the locations with feral OSR ranged from less than 10% to 100%. Our investigations gave clear empirical evidence that feral OSR was, on average, at least 41% smaller than cultivated OSR, independent of phenological state after onset of flowering. DISCUSSION: The findings can be interpreted as phenotypic adaptation of feral OSR plants. Therefore, it must be asked whether dwarfing could be interpreted as an improvement of pre-adaptation to feral environments. In most of the sites where feral plants occurred, germination and establishment were in locations with disturbed vegetation cover, allowing initial growth without competition. Unless feral establishment of genetically modified dwarfed traits are specifically studied, it would not be safe to assume that the mitigation strategy of dwarfing also reduces dispersal in feral environments. CONCLUSIONS AND RECOMMENDATIONS: With respect to OSR, we argue that the proposed mitigation approach could increase escape and persistence of transgene varieties rather than reducing them. We conclude that the development of effective hazard mitigation measures in the risk evaluation of genetically modified organisms requires thorough theoretical and empirical ecological analyses rather than assumptions about abstract fitness categories that apply only in parts of the environment where the plant can occur.     

改性聚丙烯酰胺固定化苯酚降解菌的研究

利用自制的改性聚丙烯酰胺为载体包埋苯酚降解菌,考查了该载体对细胞性能的影响,比较了4种固定化方法--改性聚丙烯酰胺法、聚丙烯酰胺法、海藻酸钙法和聚乙烯醇-海藻酸钙法包埋微生物细胞的优劣.实验结果表明,单体丙烯酰胺经改性后制得的改性聚丙烯酰胺对微生物细胞活性无影响.以其为载体固定苯酚降解菌,其细胞相对活性比聚丙烯酰胺法高出了42.4%;比海藻酸钙法高出了16.4%;比聚乙烯醇.海藻酸钙法高出了44.3%,表明改性聚丙烯酰胺包埋细胞更有利于细胞的增殖和活性恢复.重复应用实验表明,改性聚丙烯酰胺法得到的细胞凝胶,机械强度好,有弹性,可多次重复利用.改性聚丙烯酰胺作为细胞固定化载体其优点是交联速度快、聚合放热温度低、在侧链发生交联反应、抗水解能力强、无毒、凝胶寿命长.     

胺硫改性生物炭对水溶液中不同重金属离子的吸附特性及吸附稳定性

以玉米秸秆为原料热裂解制备生物炭,利用二乙烯三胺和二硫化碳,通过酸化氧化,曼妮希反应胺基改性、二硫化碳巯基取代对生物炭进行胺硫双基团改性,研究胺硫改性生物炭(BC-SN)对Pb2+、Ni2+及Cd2+在单一和三元体系下的吸附特性和吸附稳定性.表征分析证实了生物炭表面胺硫双基团改性成功,且具有比表面积大、表面官能团丰富的...