上海市典型城市河岸带不同植被类型下土壤反硝化作用研究

为了解城市河岸带不同植被类型下土壤的反硝化速率及其影响因子，在上海市城市河岸带的长风绿地选择了熊掌木、硕苞蔷薇和矮生百慕大草3种植被类型，于2012年3月（春初）、5月（春季）、7月（夏季）、11月（秋季）测定了其下不同深度（2～5 cm、12～15 cm、22～25 cm和32～35 cm）土壤的反硝化速率和土壤的粒度、含水率、SOC、NH4+和NO3-含量等基本理化性质。结果表明:长风绿地3种植被类型下土壤理化性质和反硝化速率具有一定的差异性，但均表现为2～5 cm深度土壤反硝化速率显著高于其他深度；熊掌木和硕苞蔷薇2~5 cm深度土壤反硝化速率均为春初显著高于其他季节，而草地2~5 cm深度反硝化速率在春夏季显著高于春初和秋季；其他深度土壤均不存在显著的季节性差异；植被类型、深度和季节对反硝化速率的单一和综合影响效应（除植被类型*深度外）均显著；反硝化速率与土壤的SOC、NH4+和NO3-含量呈极显著正相关（p<001），而与土壤含水率和气温没有显著相关关系     

Pros and cons of climate change in China

Climate change strongly affected the structure and functions of natural ecosystems,e.g.the vegetation productivity decreased in the Northeast permafrost region due to the higher temperature and less precipitation,whereas in the Tibetan Plateau,the vegetation productivity increased,owing to the improved thermal resource.Climate change led to reduced precipitation in North and Northeast China and thus the reduced surface runoff.The public needs for energy were changed because of climate change,e.g.the shorter heating period in winter.Climate change profoundly influenced human health,pathophoresis and major projects by increasing extreme events,including frequency and magnitude,and causing more serious water shortage.Under the background of climate change,although the improved thermal resources can be helpful for extending the crop growth period,more extreme events may resulted in more instability in agricultural productivity.Not only did climate change indirectly affect the secondary and tertiary industries through the impacts on agriculture and natural resources,but also climate change mitigation measures,such as carbon tax,tariff and trading,had extensive and profound influences on the socioeconomic system.Further analysis indicated that the impact of climate change presented significant regional differences.The impact had its pros and cons,while the advantages outweighed the disadvantages.Based on the above analysis on the impacts of climate change,we put forward suggestions on coping with climate change.First,scientifically dealing with climate change will need to seek advantages while avoiding the disadvantages of climate change in order to achieve the orderly adaptation to climate change,which is characterized with"Overall best,long-term benefit."Second,quantitative adaptation should be given more attention,e.g.proposing operational schemes and predictable goals and using uncertainty analysis on adaptation measures.Third,more active coping strategy should be adopted to enhance China's future comprehensive competitiveness.The strategies include but are not limited to gradually adjusting the industrial structure,intensifying the research and development(RD)of emission reduction technology and actively responding to the influence of carbon tax,tariff and trading on socioeconomic development in China.     

南苕溪支流锦溪水质时空变化特征分析

综合运用灰色聚类法、综合污染指数法、等级聚类法就南苕溪支流锦溪近年水质时空变化特征进行分析。结果表明,锦溪入青山水库断面水质2005—2009年逐年改善,2007年后达到灰色聚类等级Ⅲ类水质要求;2009年秋季至2010年夏季期间秋、冬两季的污染程度高于春、夏季节;枯水期综合污染指数最高,但TN、TP污染分指数在丰水期最高,表明污染源中面源污染已占相当比例。空间变化方面从玲珑桥到江桥锦溪水质的综合污染指数不断提升,到江桥时达到极值13.25,锦溪末端三眼桥断面水质较江桥断面有所改善;SPSS空间聚类分析可分为轻污染区(从玲珑桥到冬韵桥)、重污染区(从群利桥到江桥)和中度污染区(从江桥到三眼桥)。锦溪上游农业区对河水中的COD、TN和TP的贡献率分别为66%、54%和49%,农业面源污染已成为制约锦溪水质改善的主要因素。     

土石坝震损机理及震害影响因素研究

汶川8.0级地震造成主震区四川省境内1997座水库的坝体、溢洪道、输水管、管理房等水利设施不同程度的损毁,不仅无法实现水利功能,而且面临洪水威胁.汶川地震中土石坝典型震害包括裂缝、滑坡、渗漏以及坝体沉陷等.在调查主震区土石坝地震损毁特点的基础上,分析了均质土坝、面板堆石坝、心墙坝等坝型主要震害产生的原因,阐述了影响土石坝震害程度的诸多因素及其作用方式,控制性因素主要有外部因素如场地类别、地震动参数,坝体内部因素如坝料特性、坝型及坝高、坝坡坡率等.     

混凝法去除城市生活污水中抗性基因

采用聚合氯化铝(PACl)和聚合硫酸铁(PFS)混凝处理城市生活污水(格栅出水和二级出水),考察混凝剂投加量、p H值对污水中抗生素抗性基因(ARGs)的去除率影响。结果表明,随着PACl和PFS投加量的增加,污水中目标基因的去除率先升高后降低;在p H 3~10的范围内,PACl对目标基因的去除效果随p H值的增加而降低,PFS对目标基因的去除随着p H值的增加先升高后降低。对于格栅出水,PACl和PFS的最佳投加量为400 mg/L,基因的去除率分别达到2.33~2.97 log和0.98~2.11 log,对于二级出水,PACl和PFS的最佳投加量分别为200 mg/L和150 mg/L,基因的去除率分别为1.85~2.64log、1.81~2.46 log;混凝去除最优p H条件分别为p H=3(投加PACl)及p H=5~6(投加PFS)。PACl的处理效果优于PFS。     

铁铈钛复合氧化物催化剂的制备及其选择性催化还原NO的性能

采用共沉淀法制备了一种新型催化剂——铁铈钛复合氧化物催化剂，研究了Fe掺加量、体积空速以及H2O和SO2的加入对其选择性催化还原NO性能的影响；采用XRD和SEM等手段对催化剂的结构和形貌进行了表征。表征结果显示，Fe的掺加使催化剂表面的颗粒更均匀，提高了催化剂的分散度。实验结果表明：以Ce（NO3）3，Fe（NO3）3?9H2O，TiOSO4?2H2O为原料、按n（Ce）∶n（Fe）∶n（Ti）=0.2∶0.8∶1配比制得的Ce0.2Fe0.8TiOx为催化剂，在反应温度250 ℃、反应时间3 h、体积空速25 000 h-1的条件下，NO去除率为99.8%，N2选择性为100%；Fe的掺加显著提高了Ce0.2Fe0.8TiOx催化剂的抗H2O和SO2的能力。     

Mechanical behavior of typical hazardous waste and its influence on landfill stability during operation

The stability of hazardous waste (HW) landfill is a major security risk to the landfill environmental safety. The mechanical behavior of waste controls many aspects of landfill design and operation, including stability and settlement issues and the integrity of geosynthetic and liner components. This study presents the results of a laboratory experiment to learn the mechanical properties of HW collected from the Hangzhou HW landfill. Measured mechanical behavior was compared with results for municipal solid waste (MSW) to assess their discrepancies. The particle size of HW was analyzed by the sieving and hydrometer methods. Because HW comes primarily from industrial plants in the form of sludge or slag, their particle sizes are generally smaller than those of MSW. This study indicates that the shear strength parameters of HW are more sensitive to the methods of testing and calculation than those of MSW. Numerical simulations demonstrate that the safety factor of a landfill is affected by the mechanical properties of HW, especially cohesion and friction angle. Because of the lower particle size and wider compression ratio, compared to MSW, an HW landfill should be taken more care in its operational procedures so as to increase its stability.     

Energy and exergy optimization of food waste pretreatment and incineration

With the aim of upgrading current food waste (FW) management strategy, a novel FW hydrothermal pretreatment and air-drying incineration system is proposed and optimized from an energy and exergy perspective. Parameters considered include the extracted steam quality, the final moisture content of dehydrated FW, and the reactor thermal efficiency. Results show that optimal working condition can be obtained when the temperature and pressure of extracted steam are 159 °C and 0.17 MPa, the final moisture content of dehydrated FW is 10%, and the reactor thermal efficiency is 90%. Under such circumstance, the optimal steam energy and exergy increments reach 194.92 and 324.50 kJ/kg-FW, respectively. The novel system is then applied under the local conditions of Hangzhou, China. Results show that approximately 2.7 or 11.6% (from energy or exergy analysis perspective) of electricity can be additionally generated from 1 ton of MSW if the proposed novel FW system is implemented. Besides, comparisons between energy and exergy analysis are also discussed.

     

Vegetative Ecological Characteristics of Restored Reed (Phragmites australis) Wetlands in the Yellow River Delta, China

In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon–Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years’ restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.     

扬水曝气强化催化氧化去除水中有机微污染物

以γ-Al2O3为载体,采用浸渍焙烧法制备了负载型催化剂RuO2-CeO2/γ-Al2O3、Fe2O3-CeO2/γ-Al2O3、Fe2O3/γ-Al2O3。在扬水曝气条件下,以西安某水源水库水为原水,考察了各催化剂对有机微污染物的净化效果,实验发现,催化剂反复多次使用并无明显失活现象,连续使用20 d以消除单纯吸附的影响后,仍然可在7 d内使UV254、CODMn、DOC的去除率分别达到38%、28%和27%。离子溶出实验表明,Fe2O3/γ-Al2O3有很好的稳定性。综合考虑处理效果、制备工艺以及制备成本,选择Fe2O3/γ-Al2O3为最佳催化剂。为了使催化剂Fe2O3/γ-Al2O3具有最佳活性,分别考察了焙烧时间、焙烧温度、浸渍液浓度、浸渍时间等,并对其制备工艺进行了优化。然后反应前后水样的分子量测定结果表明,反应后大分子比例下降,而小分子比例提高,说明催化氧化将一定量的大分子降解成为小分子。