土地承载力研究范式的变迁、分化及其综论

基于Kuhn范式理论,将现有土地承载力研究成果显化、梳理为4种主要研究范式,即基于限制因子的研究范式、基于多因素综合的研究范式、基于参照区的研究范式、基于生态足迹的研究范式。以范式应用的时代背景、空间尺度为着眼点,对各类范式进行综合比较,结果显示：基于限制因子的土地承载力研究范式起源最早、发展最为成熟,基于多因素综合、基于参照区、基于生态足迹的3种研究范式,均是以前者为基础,按照不同的方向分化而成;范式分化的原因在于时空条件的变化所引致的亟需解释、解决的现实问题的变化。范式本身并无优劣之分,但有其独特的适应性：基于限制因子、基于生态足迹的两种研究范式适用于全球及国家等大尺度土地承载力问题,且发展较为成熟,其成果具有较强的理论和实践指导意义;基于多因素综合及基于参照区的两种研究范式适用于市县等中小尺度,但其研究较为薄弱,所得的承载力分值、承载力相对值对区域土地管理实践的指导价值有限。当前,市县等中小尺度土地承载力研究亟需加强,其指导实践的有效性与可操作性亟待大幅度提高。     

生物基聚合物PHBV和PLA复合材料在不同介质中的生物降解及其影响因素

传统工艺的塑料生产不仅依赖石油资源的持续开发利用,同时给环境造成了前所未有的压力,近年来生物基聚合物（聚（3-羟基-3-戊酸酯）-PHBV,聚乳酸-PLA）日渐成为传统石油基塑料的替代产品.本文采用呼吸测试手段,旨在揭示均质复合材料在不同环境介质（土壤、熟化堆肥、水体）条件下及有机添加剂（木质素）,无机添加剂（蒙脱石）和天然有机物链增长剂（Joncryl）作用下的生物降解特征.结果表明：当链增长剂Joncryl添加量为5%时,对所有介质PHBV和PLA复合材料产生显著抑制作用.Joncryl添加量为0.2%时,未对所测样品的生物降解行为产生干扰作用.在熟化堆肥介质中,PLA复合材料比PHBV基质混合物的生物降解速率明显降低.有机木质纤维添加剂（榛子壳粉末）单独在聚合物中添加或者和链增长剂Joncryl以及非有机添加剂（Dellite72T）共同作用下都可促进PLA聚合物中各组分的相容连接性.实验结果表明,新型添加剂在不同介质中以二元或三元添加的方式对生物降解过程产生重要影响,该研究将为新型材料使用后的生物降解效应提供理论依据.     

构树修复对重金属污染土壤环境质量的影响

通过温室盆栽试验,研究构树（Broussonetia papyrifera）生长对重金属污染土壤酶活性和微生物群落结构的影响.结果表明,构树修复污染土壤中酶活性和微生物多样性明显提高.经270d培养后,构树生长土壤中蔗糖酶和酸性磷酸酶活性与种植土壤相比分别显著（P<0.05）提高3.12倍和2.29倍;土壤脱氢酶与有效态As、Cd、Pb、Zn和Cu含量,蔗糖酶与有效态Cd含量,以及磷酸酶与有效态Cd和Cu含量之间呈显著负相关（P<0.05）.根据16S和18S rDNA PCR-DGGE分析表明,构树修复可提高污染土壤中细菌和丛枝菌根真菌多样性.上述结果表明,构树修复可有效改善重金属污染土壤的环境质量.然而,污染土壤中重金属有效态含量下降不明显,必须辅助物理和化学措施来强化构树对重金属污染土壤的生态修复潜力.     

互花米草入侵对长江口湿地土壤碳动态的影响

为了评价互花米草入侵对长江河口湿地土壤碳动态的影响,利用配对的试验设计在长江口崇明东滩湿地的高潮滩和低潮滩各设置1条入侵种互花米草与土著种的配对样线.结果表明,与土著植物相比,互花米草入侵显著增加了长江口湿地的植物碳库、土壤微生物碳、土壤总碳库和有机碳库,而对占土壤总碳库60%以上的无机碳库无显著影响,意味着互花米草入侵导致的土壤总碳库改变主要是通过增加土壤有机碳库来实现的.高潮滩互花米草和芦苇群落的年均土壤呼吸强度分别为（210.02±4.90）,（157.79±6.39）mg/（m²·h）;低潮滩互花米草和海三棱藨草群落年均土壤CO₂排放速率分别为（157.41±5.27）,（110.90±5.16）mg/（m²·h）,表明互花米草入侵显著增加长江口湿地的土壤呼吸.上述结果意味着互花米草入侵同时增加土壤碳输入和碳输出,但入侵也显著增加了土壤碳库表明入侵增加的土壤碳输入显著高于增加的土壤碳输出.本研究表明互花米草入侵可能会增强了长江河口湿地的土壤碳汇强度和固碳能力.但仍然需要长期系统的监测研究,以便全面定量评估互花米草入侵我国滨海湿地的综合生态影响.     

Effects of Na+ on Cu/SAPO-34 for ammonia selective catalytic reduction

Copper-exchanged chabazite (Cu/CHA) catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na⁺ ions on Cu/SAPO-34 for ammonia selective catalytic reduction (NH₃-SCR) are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na⁺ ion-exchanges with H⁺ and Cu^2 + of Cu/SAPO-34. The exchange of H⁺ is easier than that of isolated Cu^2 +. The exchanged Cu^2 + ions aggregate and form “CuAl₂O₄-like” species. The NH₃-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu^2 + and acid sites is responsible for the activity loss.     

Investigating the bacterial community and amoebae population in rural domestic wastewater reclamation for irrigation

Reclamation of domestic wastewater for agricultural irrigation is viewed as a sustainable option to create an alternative water source and address water scarcity. Free-living amoebae(FLA), which are amphizoic protozoa, are widely distributed in various environmental sources. The FLA could cause considerable environmental and health risks. However, little information is available on the risk of these protozoa. In this study, we evaluated the feasibility using rural domestic wastewater for agricultural irrigation, and analyzed dynamic changes of the microbial community structure and FLA populations in raw and treated wastewater, as well as the phyllosphere and rhizosphere of lettuce production sites that were irrigated with different water sources. The bacterial community dynamics were analyzed by terminal restriction fragment length polymorphism(T-RFLP). The bacterial community structures in the influent were similar to that in the effluent, while in some cases relative abundances varied significantly. The populations of Acanthamoeba spp. and Hartmannella vermiformis in the anaerobically treated wastewater were significantly higher than in the raw wastewater. The vegetables could harbor diverse amoebae, and the abundances of Acanthamoeba spp. and H. vermiformis in the rhizosphere were significantly higher than in the phyllosphere. Accordingly, our studies show insight into the distribution and dissemination of amoebae in wastewater treatment and irrigation practices.     

房屋建筑工程施工现场环境保护以及节能降耗控制措施研究

房屋建筑施工阶段是建筑工程中最为重要的阶段,也是资源消耗和环境污染的集中阶段。房屋建筑施工造成的环境污染主要来源于:施工中的固体垃圾、液体垃圾和气体垃圾,且在施工现场,相关人员节能降耗意识薄弱,对于施工中存在的资源浪费现象经常会忽视。基于此,给出了如下措施:加强施工过程的监控,合理排放施工现场的污水和固体废弃物;提高水的利用率,并在施工过程中,通过节水工艺对路面进行喷洒;合理排放施工过程产生的污水,对含有化学品、油漆的建筑材料要实施防渗漏措施;设置封闭式垃圾容器,利用袋装化形式将施工垃圾带出施工现场;倡导绿色施工。