零价铁降解4-氯硝基苯动力学研究

实验采用无氧条件下不同浓度零价铁降解硝基芳香烃代表物4-氯硝基苯,研究4-氯硝基苯的降解速率及各产物的反应速率.根据化学反应计量学,通过准一级动力学方程对实验结果进行拟合,得到生成各产物反应速率,并利用穆斯堡尔技术检测零价铁的产物.结果表明,4-氯硝基苯的还原转化速率与零价铁浓度有关,中间产物4-氯亚硝基苯和4-氯苯基羟胺的生成和转化速率可通过拟合各反应速率得到.当零价铁浓度为1.04 g.L-1时4-氯硝基苯反应速率最快,反应速率常数为0.189min-1.反应过程中生成的亚铁离子在反应初期吸附在零价铁表面,各物质的生成和还原速率取决于零价铁表面的活性位点和各物质与零价铁之间的质量传递.     

生物炭添加对两种类型土壤DOC淋失影响

生物炭能增加土壤碳库贮量,对全球碳的生物地球化学循环和缓解全球气候变化起到不可忽视的作用。可溶性有机碳(DOC)是土壤碳库中十分重要的组分,研究生物炭对DOC淋失影响对深入了解生物炭对土壤有机碳循环具有重要意义。本文以新疆和河南两种土壤为对象,通过室内土柱淋滤试验研究生物炭添加对不同类型土壤中溶解性有机碳(DOC)淋失影响以及添加不同生物炭对同种土壤淋滤液中DOC淋失影响特征。结果表明,新疆和河南土壤淋滤液DOC浓度和淋失量随着生物炭添加比例增加(1%,5%,10%)而减少。与玉米秸秆和锯末混合物为原料制成生物炭相比,玉米秸秆生物炭能显著降低新疆土壤淋滤液中DOC浓度。     

The Role of Botanic Gardens in the Science and Practice of Ecological Restoration

Abstract: Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant‐based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science‐based support to restoration efforts. We recommend botanic gardens widen research to include ecosystems as well as species, increase involvement in practical restoration projects and training practitioners, and serve as information hubs for data archiving and exchange.     

Integrated Monitoring and Information Systems for Managing Aquatic Invasive Species in a Changing Climate

Abstract:  Changes in temperature, precipitation, and other climatic drivers and sea-level rise will affect populations of existing native and non-native aquatic species and the vulnerability of aquatic environments to new invasions. Monitoring surveys provide the foundation for assessing the combined effects of climate change and invasions by providing baseline biotic and environmental conditions, although the utility of a survey depends on whether the results are quantitative or qualitative, and other design considerations. The results from a variety of monitoring programs in the United States are available in integrated biological information systems, although many include only non-native species, not native species. Besides including natives, we suggest these systems could be improved through the development of standardized methods that capture habitat and physiological requirements and link regional and national biological databases into distributed Web portals that allow drawing information from multiple sources. Combining the outputs from these biological information systems with environmental data would allow the development of ecological-niche models that predict the potential distribution or abundance of native and non-native species on the basis of current environmental conditions. Environmental projections from climate models can be used in these niche models to project changes in species distributions or abundances under altered climatic conditions and to identify potential high-risk invaders. There are, however, a number of challenges, such as uncertainties associated with projections from climate and niche models and difficulty in integrating data with different temporal and spatial granularity. Even with these uncertainties, integration of biological and environmental information systems, niche models, and climate projections would improve management of aquatic ecosystems under the dual threats of biotic invasions and climate change.     

Strategies for Emission Reduction of Air Pollutants Produced from a Chemical Plant

Various air pollution control (APC) techniques were employed in order to reduce emissions of air pollutants produced from chemical plants, which have many different chemical production facilities. For an emission reduction of acid gases, this study employed a method to improve solubility of pollutants by decreasing the operating temperature of the scrubbers, increasing the surface area for effective contact of gas and liquid, and modifying processes in the acid scrubbers. To reduce emission of both amines and acid gases, pollutant gas components were first separated, then condensation and/or acid scrubbing, depending on the chemical and physical properties of pollutant components, were used. To reduce emission of solvents, condensation and activated carbon adsorption were employed. To reduce emission of a mixture gases containing acid gases and solvents, the mixed gases were passed into the first condenser, the acid scrubber, the second condenser, and the activated carbon adsorption tower in sequence. As a strategy to reduce emission of pollutants at the source, this study also employed the simple pollution prevention concept of modification of the previously operating APC control device. Finally, air emissions of pollutants produced from the chemical plants were much more reduced by applying proper APC methods, depending upon the types (physical or chemical properties) and the specific emission situations of pollutants.     

A reactor system combining reductive dechloirnation with cometabolic oxidation for complete degradation of tetrachloroentylene

A laboratory sequential anaerobic aerobic bioreactor system, which consisted of an anaerobic fixed film reactor and two aerobic chemostats, was set up to degrade tetrachloroethylene (PCE) without accumulating highly toxic degradation intermediates. A soil enrichment culture, which could reductively dechlorinate 900μM (ca. 150 mg/L) of PCE stoichiometrically into cis-1,2-dichloroethylene ( cis-DCE), was attached to ceramic media in the anaerobic fixed film reactor. A phenol degrading strain, Alcaligenes sp. R5, which can efficiently degrade cis-DCE by co metabolic oxidation, was used as inoculum for the aerobic chemostats consisted of a transformation reactor and a growth reactor. The anaerobic fixed film bioreactor showed more than 99 % of PCE transformation into cis DCE in the range of influent PCE concentration from 5μM to 35μM at hydraulic retention time of 48h. On the other hand, efficient degradation of the resultant cis-DCE by strain R5 in the following aerobic system could not be achieved due to oxygen limitation. However, 54% of the maximum cis-DCE degradation was obtained when 10 μmol of hydrogen peroxide (H₂O₂) was supplemented to the transformation reactor as an additional oxygen source. Further studies are needed to achieve more efficient co metabolic degradation of cis DCE in the aerobic reactor.     

A survey of arsenic and other heavy metals in vegetation from markets or mine tailings

This research includes two investigations. The first one is a market basket survey of the levels of arsenic （As） and trace elements in bracken fern （Pteridium aquilinum） originated from three countries： South Korea, China and North Korea. The results showed that the mean As concentrations in stems of samples were significantly higher than those in leaves. As concentrations in all samples did not exceed food safety limits for vegetables. Generally, concentrations of Fe, Mn, Cu and Zn in leaves were higher than those in stems. The second investigation is a survey on the levels of As and other heavy metals in vegetation in the vicinity of Myoungbong mine tailings. The results demonstrated that As, Pb and Cu concentrations and bioaccumulation factors （BCF） in seedlings of the fern（A splenium achilleifolium） were the highest, whereas Marsh horsetail（Equisetum polustre） accumulated the highest levels of Zn. Concentrations of As, Pb, Zn and Cu in vegetable-cress （Lepidium sativum） and the edible herb-aromatic madder （Elasholtzia splendens） were higher than food safety limits. Therefore, a risk assessment of As and other heavy metals in vegetables and herbs on local human health should be conducted in the future.     

Decomposition of CCl4 and CHCl3 on gliding arc plasma

Introduction C hlorinated volatile organic com pounds(C V O C s) w ere released to the atm osphere as flue gases from various industrial processes. C hlorinated hydrocar- bons have been w idely accepted as solvents and chem ical interm ediates in the m an…     

Planning for Climate Change: Identifying Minimum-Dispersal Corridors for the Cape Proteaceae

Abstract:  Climate change poses a challenge to the conventional approach to biodiversity conservation, which relies on fixed protected areas, because the changing climate is expected to shift the distribution of suitable areas for many species. Some species will persist only if they can colonize new areas, although in some cases their dispersal abilities may be very limited. To address this problem we devised a quantitative method for identifying multiple corridors of connectivity through shifting habitat suitabilities that seeks to minimize dispersal demands first and then the area of land required. We applied the method to Proteaceae mapped on a 1-minute grid for the western part of the Cape Floristic Region of South Africa, to supplement the existing protected areas, using Worldmap software. Our goal was to represent each species in at least 35 grid cells (approximately 100 km²) at all times between 2000 and 2050 despite climate change. Although it was possible to achieve the goal at reasonable cost, caution will be needed in applying our method to reserves or other conservation investments until there is further information to support or refine the climate-change models and the species' habitat-suitability and dispersal models.