元江流域干热河谷草地植物群落结构特征与相似性分析

选择元江干热河谷典型草地群落,采用标准样地调查法,对流域上、中、下游干热河谷草地植物群落的分布特征、群落结构、种群习性等特征开展研究,结果表明：（1）元江流域上游祥云和中下游红河干热河谷草地群落中出现的植物种类最多,元江流域干热河谷草地植物群落是以灌木为主、多年生草本为辅的结构类型。（2）元江流域干热河谷草地群落中,扭黄茅（Heteropogon contortus）为优势种群,次优种群随流域环境的改变而不同。（3）元江流域干热河谷草地植物群落之间的相似性系数均在0.00～0.25之间,处于极不相似水平,种群的扩散受流域河谷通道作用影响较小。（4）种群的扩散和定居受海拔高度的影响,随着海拔高度的变化,植物群落的组成也发生变化,形成不同的群落结构。     

Screening of the marine actinomycetes with anti-complement activity and isolation of the active fractions北大核心CSCD

Studies on anti-complement agents are essential for the development of drugs to treat various diseases caused by excessive or abnormal activation of the complement system. However, studies on microbial-derived anti-complement agents are still very limited. The anti-complement activities of 42 marine-derived actinomycete strains isolated from the sediment samples collected from Xinghai Bay in Dalian were studied using the hemolysis method. In addition, the active fractions of the strain Streptomyces sp. DUT11 were separated by C18 and Sephadex LH-20 column chromatography, and the active compounds with anti-complement activity were identified. Streptomyces strains S187, M5, S088, M8, S063, DUT11 and MD16 showed good anti-complement activities upon being cultured in TSB medium, with the strain DUT11 showing the best anti-complement activity among these strains. When different fermentation media were tested, the highest anti-complement activity of DUT11 was observed in M33 fermentation medium. The anti-complement activity was 56.5% for the extract of supernatant and 60.8% for the extract of mycelia, respectively. Furthermore, three compounds with anti-complement activity were obtained from the active components, which were identified as 3-indolecarboxylic acid (1), p-hydroxy benzoic acid (2) and 2-pyrrolecarboxylic acid (3). These results demonstrated that marine-derived streptomycetes can be employed to produce active compounds with anti-complement activity. This study presents a new alternative for the utilization of marine actinomycetes and provides a basis for the exploration of new anti-complement agents. © 2018 Science Press. All rights reserved.     

Simulating secondary succession of elk forage values in a managed forest landscape,western Washington

Modern timber management practices often influence forage production for elk (Cervus elaphus) on broad temporal and spatial scales in forested landscapes. We incorporated site-specific information on postharvesting forest succession and forage characteristics in a simulation model to evaluate past and future influences of forest management practices on forage values for elk in a commercially managed Douglas fir (Pseudotsuga menziesii, PSME)-western hemlock (Tsuga heterophylla, TSHE) forest in western Washington. We evaluated future effects of: (1) clear-cut logging 0, 20, and 40% of harvestable stands every five years; (2) thinning 20-year-old Douglas fir forests; and (3) reducing the harvesting cycle from 60 to 45 years. Reconstruction of historical patterns of vegetation succession indicated that forage values peaked in the 1960s and declined from the 1970s to the present, but recent values still were higher than may have existed in the unmanaged landscape in 1945. Increased forest harvesting rates had little short-term influence on forage trends because harvestable stands were scarce. Simulations of forest thinning also produced negligible benefits because thinning did not improve forage productivity appreciably at the stand level. Simulations of reduced harvesting cycles shortened the duration of declining forage values from approximately 30 to 15 years. We concluded that simulation models are useful tools for examining landscape responses of forage production to forest management strategies, but the options examined provided little potential for improving elk forages in the immediate future.     

Copper recycling and scrap availability

According to existing estimates, available old copper scrap has more than tripled over the past 40 years. Secondary production (that is, copper produced from recycling old scrap), however, has only doubled. Indeed, over the past 10 years, while copper consumption and primary production have continued to expand briskly, while available old scrap has increased by over 35%, secondary production has actually stagnated.For a world concerned with sustainable development and the quality of the earth's environment, this performance is disappointing and in need of explanation. Other things being equal, one would expect the amount of recycling to increase with the availability of scrap, as many econometric models of the world copper market developed over the past several decades explicitly assume.The key to understanding sluggish growth in secondary production, this paper argues, is distinguishing carefully between (1) the flow of old scrap that arrives each year from products reaching the end of their useful lives during the year and (2) the available stock of old scrap that was not recycled during earlier years presumably because it was too costly to do so. Using an econometric model, the paper shows that old scrap stocks, which have contributed most of the increase in available old copper scrap over the years, have a very modest impact on secondary production. Old scrap flows have a much greater effect, but they account for only about 4% of the available old scrap for any given year.     

二次加压泵房噪声与振动治理

针对楼盘受低频噪声的困扰,本文提出建筑物内的设备运行造成的结构传声是扰民的主要声源。研究了二次加压泵房噪声与振动的特性,在此基础上研究了设备的隔声、隔振技术,并成功应用于实际项目中。     

原油储罐火灾事故环境风险评价分析

通过运用ADMS模型,对2万m3原油储罐发生火灾爆炸事故时有毒有害气体及燃烧次生污染物的环境影响进行预测。结果表明,其产生的废气污染物对环境影响较大;在火灾持续6h的情况下,产生的主要废气污染物在距离事故中心120m范围内的人员将有半数死亡;距120～240m范围内造成组织缺氧;距240～4725m人员不会有生命危险;距离4725m范围内污染物的浓度超出车间最高允许浓度要求。同时提出了相应的环境风险管理措施,为今后类似事故环境影响评价作借鉴,为环保部门环境管理提供参考。     

垂直管理背景下建设二级环境监测站能力的策略

尽管近些年我国经济已经得到了较大的发展,但是与此同时也带来了严重的环境污染问题,在新的时代背景下,国家越来越重视环境整治力度,因此做好环境监测工作显得尤为重要。为了发挥出环境监测站的工作职能,目前该领域朝着垂直管理的方向不断发展,有效地提高了整体的质量管理意识,建立起了标准的工作体系。本文将着重针对在垂直管理背景下如何提高二级环境监测站能力进行深入分析。     

ZnO NPs对水培小麦(Triticum aestivum L)种子不同发育阶段的影响

氧化锌纳米颗粒(ZnO NPs)是目前应用最为广泛的纳米材料之一,已有研究表明其对生物体具有显著的毒性效应。为了研究ZnO NPs的毒性与种子发育阶段的关系,选择小麦(Triticum aestivum L)作为受试植物,将处于不同发育阶段的小麦种子置入ZnO NPs悬浮液中进行培养,研究了ZnO NPs对水培小麦种子不同发育阶段的影响。结果表明,虽然ZnO NPs对处于吸胀阶段、萌动阶段和发芽阶段的小麦都可以产生毒性,但是毒性的大小随小麦发育阶段的不同而表现出明显的差异(P0.05)。在60 mg·L-1暴露浓度下,用ZnO NPs对处于吸胀阶段、萌动阶段和发芽阶段的小麦种子进行处理,小麦根长的抑制率分别为37.8%、80.2%和95.7%;就萌动阶段和发芽阶段而言,ZnO NPs的毒性与其浓度有关,浓度越大毒性越大,即具有显著的浓度效应。上述研究结果对于全面准确地评价ZnO NPs毒性具有重要的意义。     

Mercury contamination in vicinity of secondary copper smelters in Fuyang, Zhejiang Province, China: Levels and contamination in topsoils

In the present study, we aim to investigate the extent of soil contamination by Hg, particularly by anthropogenic Hg, and tentatively estimate the total Hg (Hg_T) accumulation in topsoils (0-15 cm) in Fuyang, Zhejiang Province—a secondary Cu smelter of China. The results show that the levels of soil Hg in the vicinity of the smelters have been substantially elevated following local smelting activities. The spatial distribution of soil Hg in this area reveals a rapid decrease as the distance from the smelter reaches 1.5 km, which is probably due to the quick deposition process of particulate Hg and reactive gaseous Hg emitted from the smelters. The total accumulation of Hg_T in the topsoils of the study area of 10.9 km² is approximately 365-561 kg and of which 346-543 kg might be contributed by anthropogenic emission alone with an annual emission of 17.3-27.2 kg Hg to the topsoils.     

Effect of oxygenated liquid additives on the urea based SNCR process

An experimental investigation was performed to study the effect of oxygenated liquid additives, H₂O₂, C₂H₅OH, C₂H₄(OH)₂ and C₃H₅(OH)₃ on NO_x removal from flue gases by the selective non-catalytic reduction (SNCR) process using urea as a reducing agent. Experiments were performed with a 150 kW pilot scale reactor in which a simulated flue gas was generated by the combustion of methane operating with 6% excess oxygen in flue gases. The desired levels of initial NO_x (500 ppm) were achieved by doping the fuel gas with ammonia. Experiments were performed throughout the temperature range of interest, i.e. from 800 to 1200 °C for the investigation of the effects of the process additives on the performance of aqueous urea DeNO_x. With H₂O₂ addition a downward shift of 150 °C in the peak reduction temperature from 1130 to 980 °C was observed during the experimentation, however, the peak reduction efficiency was reduced from 81 to 63% when no additive was used. The gradual addition of C₂H₅OH up to a molar ratio of 2.0 further impairs the peak NO_x reduction efficiency by reducing it to 50% but this is accompanied by a downward shift of 180 °C in the peak reduction temperature. Further exploration using C₂H₄(OH)₂ suggested that a 50% reduction could be attained for all the temperatures higher than 940 °C. The use of C₃H₅(OH)₃ as a secondary additive has a significant effect on the peak reduction efficiency that decreased to 40% the reductions were achievable at a much lower temperature of 800 °C showing a downward shift of 330 °C.