金属镁渣的回收利用现状

近年来,我国镁冶炼行业快速发展,随着原镁和镁合金年产量的逐年增高,排放出来的镁渣也越来越多,如何有效合理地处理、开发利用镁渣,达到节约能源、节约资源、变废为宝和变害为利的目的,是当前迫切需要解决的问题。对近年来我国有关镁渣的研究应用情况进行全面的总结。     

Analysis of polychlorinated dibenzo-p-dioxins and furans in various aqueous samples in Taiwan

Twenty-one fresh water samples were taken from reservoirs, wells and drinking water treatment plants in Taiwan for measurement of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) concentrations. Due to low concentration of PCDD/Fs, water samples (400-1000 L) were collected by using the on-site large volume pre-concentration system and analyzed by high resolution gas chromatography (HRGC)/high resolution mass spectrometer (HRMS). Different characteristics of dioxin profiles in surface water and groundwater are observed. The PCDD/F concentrations in fresh water samples varied from 0.001 to 0.265 pg WHO₉₈-TEQ/L which are lower than the standard (12 pg WHO₉₈-TEQ/L) set by the Taiwan Environmental Protection Administration (TEPA) for drinking water. Only a small fraction (<5%) of the total PCDD/F concentration in fresh water samples was water-soluble. As a result of their hydrophobicity, PCDD/Fs are effectively removed along with suspended solid via the water treatment process (average 98% removal efficiency).     

基于土壤侵蚀模型的滑波临界雨量估算探讨

针对滑坡临界雨量确定目前存在的问题,提出一种基于土壤侵蚀模型的滑坡临界雨量估算的新方法。该方法基本思路是：降雨引起土壤侵蚀,当土壤侵蚀达到一定强度时可诱发滑坡,因此利用土壤侵蚀模型可以推算滑坡临界雨量。以湖北省秭归县为例进行试验,从降雨-土壤侵蚀-滑坡的成灾机理入手,利用卫星资料、地理信息资料及降雨资料,计算降雨侵蚀力、土壤可蚀性、地形（坡长、坡度）、植被覆盖和土地利用类型等因子,基于USLE土壤侵蚀模型,计算滑坡发生时土壤侵蚀强度,通过分析多个滑坡个例,确定滑坡临界土壤侵蚀强度,再根据降雨侵蚀力与降雨量之间的关系,推算不同预警点滑坡临界雨量。相比以往仅仅分析灾情与降雨之间关系的传统方法,该方法有较为清晰的物理意义,实际业务中也易于实现,在滑坡预警预报中有较高实用价值     

Anthropogenic N2O production from landfill leachate treatment

The results of a field survey and laboratory study indicated that nitrogenous landfill leachate treatment can be a significant potential source of N2O emission. Nil (raw leachate) to 58.8ngmL(-1)h(-1) (sequential batch reactor) N2O emission was detected at five treatment plants in South China. The production and emission of N2O was especially high soon after the raw leachate was aerated. The emission was positively correlated with the dissolved N2O content in leachate; detected dissolved N2O ranged from 0 to 1309ngmL(-1). All leachate treatment plants studied were effective in NH4+-N removal (>95%); however, the highest N2O emission was estimated to be 0.25g N2Ocapita(-l)year(-1), comparable with the rate of N2O emission in conventional sewage treatment process.     

Synergistic effects of chromium and copper on photosynthetic inhibition,subcellular distribution,and related gene expression in Brassica napus cultivars

Environmental Science and Pollution Research - Nowadays, modern plant physiology focuses on complex behavior of metal co-contaminants in agrosystems. Keeping this in view, the current study was...     

喀斯特地区城镇化质量与土地利用系统健康协同演化关系研究

在城镇化过程中,城镇化质量与土地利用系统健康存在着相互联系、相互影响的耦合关系,只有当两者协调发展,才能进一步促进城镇化的协调发展。以喀斯特地区贵阳市为研究对象,在构建了城镇化质量和土地利用系统健康的评价指标体系后,分别计算了两者的综合指数,并采用耦合度模型与耦合协调模型以及剪刀差方法对两者的协调关系进行分析。研究表明：（1）城镇化质量和土地利用系统健康的综合〖JP+2〗指数大体上呈逐年上升的趋势,其中土地利用系统健康先后经历了从亚健康到初级健康再到中级健康的状态;（2）城镇化质量与土地利用系统健康的耦合度在研究期内一直处于拮抗水平,耦合协调水平先后经历了从濒临失调到勉强协调再到初级协调的状态;（3）城镇化质量与土地利用系统健康演化速率的剪刀差较为稳定,波动趋势比较平缓,贵阳市城镇化质量与土地利用系统健康这两个系统发展演化速率的差异基本维持在稳定水平。在未来应当采用促进城镇化质量与土地利用系统健康双向提升的优化路径以提高两个系统之间的耦合关系     

六六六(HCHs)在小白洋淀水生植物中的分布与富集

利用GC-ECD测定了小白洋淀6个采样点的9种浮水、挺水和沉水植物中4种六六六(hexachlorocyclohexanes,HCHs)异构体的含量,分析了其分布、组成及富集特征。结果表明:1)小白洋淀水生植物中总HCHs含量范围在ND~7.47 ng·g-1(ww),浮水植物中HCHs含量最高,挺水植物各组织含量也有明显差异,根部HCHs含量明显高于茎叶2种组织。2)4种HCHs异构体中,γ-HCH的残留水平要显著高于其他3种异构体。在沉水植物和浮水植物中,均以γ-HCH占绝对比例,相对含量达60%~99%;而在挺水植物中,δ-HCHs占有较高比例,并且主要富集在挺水植物的根部,茎中次之,叶中最少。3)小白洋淀浮水植物和沉水植物HCHs含量与水体中HCHs含量呈显著的正相关关系,而挺水植物荷花、蒲草中HCHs各组分含量与水体中HCHs的相关关系不显著。4)水生植物对水中HCHs的富集系数BCF在8.7~661.2范围;浮水植物的BCF最高,沉水植物次之,挺水植物的茎对水体中HCHs的BCF最低。     

Applicability of sustainable urban drainage systems: an evaluation by multi-criteria analysis

Urban flooding has become more serious and worldwide in recent years, especially in the big cities of developing countries. This study uses a multi-criteria analysis (MCA) approach to evaluate the applicability of sustainable urban drainage systems (SUDS), a flood control measure, in the central part of Ho Chi Minh City, Vietnam. The output of the personal computer storm water management model along with interviews with 140 households was used to assess the efficacy and acceptability of four SUDS alternatives: rainwater harvesting, green roof, urban green space and pervious pavement. On technical performance, green roof was the best alternative, followed by pervious pavement, urban green space and rainwater harvesting. Results of the social survey, however, diverged largely from the results of the technical assessments. In particular, people generally prefer public SUDS such as urban green space and pervious pavements to household solutions. With respect to the MCA, we applied four different procedures: Borda count, pair-wise voting, range of value and analytic hierarchy process. Despite some differences, the integrated results from MCA largely agree that urban green space is the most favourable type of SUDS, followed by green roof, pervious pavement and rainwater harvesting.     

Oxidation of Cyclic Ethers by Alkane‐Grown Mycobacterium vaccae JOB5

In this study we investigated the cometabolic oxidation of six cyclic ethers by alkane‐grown Mycobacterium vaccae JOB5. These ethers include, among others, tetrahydrofuran (THF), 1,4‐dioxane (14D), 1,3‐dioxolane (13DO), and tetrahydropyran (THP). Cells grown on propane, n‐butane, n‐pentane, isobutane, or isopentane oxidized all six ethers. Ether‐degrading activity was inhibited by acetylene in alkane‐grown cells and was largely absent from cells grown on dextrose‐containing media. Propane competitively inhibited THF oxidation. γ‐Butyrolactone (γBL) accumulated and was also further oxidized during THF oxidation by propane‐grown cells. In contrast, no products were detected during 14D oxidation. Propane‐grown cells also rapidly oxidized 3‐hydroxytertrahydrofuran and exhibited strong hemiacetal‐oxidizing activity in an assay following methyl formate production from mixtures of methanol and formaldehyde. These observations suggest γBL is likely generated during THF oxidation through further oxidation of 2‐hydroxytetrahydrofuran. Limited growth of strain JOB5 was supported by several cyclic ethers and the corresponding lactones and diols potentially derived from these compounds. However, strain JOB5 grew more readily on 4‐hydroxybutyrate, the product of γBL hydrolysis. The ability of strain JOB5 to productively assimilate THF‐derived metabolites during growth on n‐alkanes was examined in carbon‐limited batch cultures. Relative to C‐limited growth on n‐pentane alone, culture growth increased up to twofold in the presence of THF while no stimulation of growth was observed in comparable experiments conducted with n‐pentane and 14D. Our results are discussed in terms of their significance to our understanding of cyclic ether cometabolism and their potential impact on approaches for cyclic ether biodegradation in the environment. © 2013 Wiley Periodicals, Inc.