人工湿地生态根孔技术及其应用

人工湿地亚表层介质的堵塞问题一直是湿地系统持续有效运行的障碍,极大地限制了人工湿地技术的大规模工程应用.通过白洋淀自然湿地现场研究,发现由大型水生植物所形成的根孔异常发达,径级不等的死活根孔混合在一起,组成了庞大的湿地根孔网络.人工湿地生态根孔技术通过模拟白洋淀湿地自然的芦苇根孔系统,以人为填埋的植物秸秆作为湿地的填料/介质,有效地改变了土壤亚表层大孔隙结构,为人工湿地建设和应用开辟了一条新途径.通过构筑根孔和自然根孔之间的过渡和湿地根孔的不断更新,实现湿地填料/介质的自我更新,克服了一般潜流人工湿地其填料/介质易发生堵塞的缺点.构筑根孔有效填补了人工湿地运行初期大量自然根孔尚未形成的空白期.该技术在小试湿地中获得了成功应用.以玉米秸秆和地肤秸秆作为小试模拟湿地的填埋介质,其填埋量体积比为2%～4%.与未填埋秸秆的基质土壤处理单元相比,填埋秸秆处理单元其导水效率和营养盐去除能力都得到了有效提高.研究结果表明:填埋秸秆腐烂后形成的构筑根孔其水分侧向入渗率是基质土壤的20倍左右.在中、低营养盐负荷情况下,填埋秸秆处理单元对溶解性总氮(DTN)去除率平均提高4.5%～27.1%;对溶解性总磷(DTP)去除率平均提高7.0%～20.4%.     

Isolation and characterization of facultative mixotrophic ammonia-oxidizing bacteria from constructed wetlands

Autotrophic ammonia-oxidizing bacteria (AOB) have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater and rhizospheres of macrophytes of constructed wetlands, and then cultivated in a mixotrophic medium containing ammonium and acetic acid. A molecular characterization was accomplished using ITS-PCR amplification, and phylogenetic analysis based on 16S rRNA gene sequences. Results showed the presence of 35 bacteria, among 400 initially heterotrophic isolates, that were able to remove ammonia. These 35 isolates were classified into 10 genetically different groups based on ITS pattern. Then, a collection of 10 isolates were selected because of their relatively high ammonia removal efficiencies (ARE ≥ 80%) and their phylogenetic diversity. In conditions of mixotrophy, these strains were shown to be able to grow (increase of optical density OD₆₆₀ during incubation with assimilation of nitrogen into cellular biomass) and to oxidize ammonia (important ammonia oxidation efficiencies, AOE between 79% and 87%). Among these facultative mixotrophic AOB, four isolates were genetically related to Firmicutes (Bacillus and Exiguobacterium), three isolates were affiliated to Actinobacteria (Arthrobacter) and three other isolates were associated with Proteobacteria (Pseudomonas, Ochrobactrum and Bordetella).     

干旱综合防御集成技术机制及在华北冬麦区的示范应用研究

论文将底墒效应利用技术、土壤深松技术、秸秆覆盖技术、有限水分胁迫效应利用技术、喷施多功能防旱剂五项单项抗旱技术在冬小麦播前及各个发育阶段适时、适地综合集成,并给出了应用量化指标。于1998～2000年在河南、河北、山东省进行示范推广应用。结果表明:冬小麦干旱综合防御集成技术是通过各单项抗旱技术触发和优化冬小麦找水、增水、保水、节水、控水的五种水分利用机制,发挥了植物生理生态、土壤理化性状、土壤水库、麦田小气候效应和化学制剂喷施等多种防旱抗旱的效能,时间贯穿于冬小麦整个生育期,可实现持续防旱抗旱。集成技术具有比各单项技术更显著的增产、节水效果。在两个典型大旱年的情况下,集成技术使水分利用效率提高10.6%～53.7%,平均提高27.7%;小麦增产7.0%～42.3%,平均增产16.6%;每公顷增加纯收入490～1200元。     

Cd2+、Cu2+和Zn2+对人工湿地反硝化作用的影响

实验室研究了 3种重金属离子 Cd²⁺、Cu²⁺、Zn²⁺对人工湿地反硝化作用的影响 .以 100、500、1000 mg/kg剂量的 Cd²⁺、Cu²⁺、Zn²⁺处理人工湿地土壤样品 ,检测其 N₂O的产生 .结果表明 ,3种金属离子的 500、1000mg/kg处理组土样 N₂O的产生均显著降低 ,各金属离子抑制 N₂O产生的程度顺序为 Cd²⁺>Zn²⁺>Cu²⁺,这与 3种金属离子在土样中的有效态浓度顺序是一致的 ,反硝化微生物在处理过程中逐步产生了对重金属离子的耐受性 ,500、1000mg/kg处理组样品的 NH⁺₄- N浓度较对照组显著升高提示部分 NO^-₃- N由于反硝化过程的抑制而异化性还原为 NH⁺₄-N.     

不同碳源添加量对垂直流人工湿地污水处理效果的影响

以垂直流人工湿地小试系统为研究对象,采用碱处理过的千屈菜(Lythrum salicaria)作为反硝化碳源补充材料,探讨了不同碳源添加量对系统COD及氮、磷去除效果的影响。结果表明,一定剂量经过碱处理的千屈菜材料可以为人工湿地系统脱氮提供反硝化所需要的碳源,而且具有缓效持续释放的特点。添加此碳源材料可明显提高系统的脱氮效率,最高可提升30.85%,但随着C/N比的增加,硝态氮去除率逐渐降低,C/N比为3、5、8时分别为91.20%、87.72%和84.19%。添加碳源量达到C/N比为3时系统能够发生最大程度反硝化,此时不仅人工湿地系统脱氮效果得到提高,同时人工湿地除磷能力也有所增强。碱处理过的千屈菜材料在本系统中的最适宜添加量为5 g,即100 g/m2(C/N=3),远低于在进水中为满足反硝化所需调控的C/N比(5～8),可以节约外加碳源成本。     

垂直潜流人工湿地中有机物去除动态规律研究

在分析垂直潜流人工湿地不同高度有机物去除率及其形态变化的基础上,推求出各形态有机物在垂向沿程的平均去除速率,建立了进水浓度和进水水力负荷规律曲线.结果表明.在本实验条件下.垂直潜流人工湿地中有机物的去除主要集中在布水管至布水管下10 cm的基质层内,进水水力负荷越小,该基质层内有机物的去除率也越高;在以粗砂作为垂直潜流人工湿地的基质、进水水力负荷≤0.5 m3/(m2·d)的条件下,垂直潜流人工湿地对有机物去除的有效高度为60 cm;布水管下10 cm基质层不同类型有机物的平均降解速率都处于最大,随着垂向沿程深度的增加.各类型有机物的平均降解速率都呈较大幅度递减趋势;以砂子为基质的垂直潜流人工湿地进水浓度和进水水力负荷规律曲线可表示为(Cin-Cou)×q=1107.02-2.96 Cin× q.     

四论灾害系统研究的理论与实践

作者曾分别于1991,1995和2001年发表了关于灾害研究理论与实践的3篇文章,对灾害系统的性质、动力学机制等进行了探讨.本文在前3篇文章的基础上,从综合灾害风险管理的角度,完善了灾害系统的结构与功能体系,论证了灾情形成过程中恢复力的作用机制,分析了区域开发与安全建设的互馈关系,构建了区域综合减灾的行政管理体系,提出了由政府、企业与社区构成的区域综合减灾范式.研究结果表明,区域灾情形成过程中,脆弱性与恢复力有着明显的区别,脆弱性是区域灾害系统中致灾因子、承灾体和孕灾环境综合作用过程的状态量,它主要取决于区域的经济发达程度与社区安全建设水平;恢复力则是灾害发生后,区域恢复、重建及安全建设与区域发展相互作用的动态量,它主要取决于区域综合灾害风险行政管理能力、政府与企业投入和社会援助水平.区域安全水平与土地利用的时空格局和产业结构关系密切,通过划定区域高风险“红线区“的办法,调整土地利用时空格局和产业结构,有利于建立区域可持续发展的综合减灾范式.针对区域自然灾害系统存在着相互作用、互为因果的灾害链规律,以及灾害系统所具有的结构与功能特征,完善由纵向、横向和政策协调共同组成的一个“三维矩阵式“的区域综合减灾行政管理体系,构建以政府为主导、企业为主体、社区全面参与的区域综合减灾范式.以此促进在发展中提高区域减灾能力,并在一定安全水平下,建设区域可持续发展模式.     

Investigation and Long-Term Monitoring of Phragmites australis Within Virginia's Constructed Wetland Sites

Phragmites australis Trin., and/or aggressive species, Typha spp. Tidally influenced wetlands that have subtidal perimeter ditches have significantly less (P < 0.05) P. australis in the wetland interior than those without perimeter ditches. Fractured regression analyses show that 6 years after construction, P. australis invasion can be extensive. Linear regression analysis suggests that, if conditions remain favorable for P. australis colonization, constructed wetlands could be overrun in 40 years.     

Monitoring a Recent Delta Formation in a Tropical Coastal Wetland Using Remote Sensing and GIS. Case Study: Guapo River Delta, Laguna de Tacarigua, Venezuela

The integrated use of remotely sensed data and GIS to monitor a rapid recent delta formation was undertaken in the Tacarigua Lagoon, a mangrove coastal protected wetland in the north-central coast of Venezuela. Recently, the resource value of coastal wetlands such as coastal lagoons and deltas, has brought about a need to protect and conserve these ecosystems. To that end, valuable resources such as these should be continuously monitored so that temporal changes in their environment can be analysed. The importance of determining the cause, extent, and spatial distribution of these changes can then be used in different aspects of environmental studies, land suitability analyses and for wise resource management. Aerospace data interpretation and a field survey were utilised to study the formation of the Guapo River delta within the Tacarigua Lagoon and to map the expansion that this depositional environment has undergone. A historical set of aerial photographs and a radar image, together with a GIS, were used to assess the growth of the delta from the beginning of its formation up to the present time.     

A/O+人工湿地工艺在乡镇污水处理厂的应用

A/O(缺氧/好氧)+复合流人工湿地处理工艺处理增城市派潭镇的酒店污水、餐饮污水、生活污水等,出水水质达到地表水Ⅲ类水质标准,可回用于农田灌溉,且处理工艺简单,处理效果好,运行稳定。