基于密度泛函理论模拟单壁碳纳米管对五种核酸碱基的吸附

基于密度泛函理论,模拟了单壁碳纳米管(SWNTs)对5种碱基的吸附作用.考察了SWNTs直径、电荷转移量、碱基最高占据分子轨道能(EHOMO)和最低未占据分子轨道能(ELUMO)与SWNTs吸附碱基的吸附能之间的关系.结果表明,随着SWNTs直径的增大,SWNTs吸附碱基的吸附能降低.SWNT(6,6)吸附5种碱基的最低吸附能Emin与由碱基转移到SWNTs的电荷转移量(Q)及碱基的EHOMO线性负相关,相关系数分别为-0.966和-0.804(P<0.05).吸附后SWNTs与碱基的前线轨道无重叠,且SWNTs电子结构未受影响,表明吸附行为属于物理吸附.     

Composition of Floating Debris in Harbours of the United States

As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources.     

The effect of imazethapyr on soil microbes in soybean fields in northeast China

Large quantities of herbicides are used on agricultural soils, but the effects of herbicides on the structure of the soil microbial community have not been well investigated. In this study, soil from three soybean fields was investigated. The herbicide imazethapyr was applied in one year to soil 1 and in two sequential years to soil 2. Control soil received no imazethapyr. Microbial biomass and community structure were characterised using chloroform fumigation–extraction and phospholipid fatty acid (PLFA) determination. The imazethapyr residue was 1.62 μ g·kg^?1 in soil 1 and 1.79 μ g·kg^?1 in soil 2. The microbial biomass carbon and total PLFAs for soil 2 were much higher than for the other soils. PLFA profiles showed that fatty acids for Gram-negative and Gram-positive bacteria, as well as total bacteria and total fungi in soil 2 were higher than in other samples. Principal component analysis of the PLFAs showed that the structure of the microbial community differed substantially among the three different soybean field soils. Application of the herbicide imazethapyr to soybean fields clearly changed the soil microbial biomass and shifted the structure of the microbial community.     

Degradation of bisphenol A by photo-fenton processes

The photo-Fenton reactions, which could yield hydroxyl radicals via the catalytic degradation of H₂O₂ by Fe(II), were focused as one of the abiotic degradation processes of bisphenol A (BPA) in surface waters. At pH 6, in the presence of H₂O₂ only, 32% of BPA was degraded after 120?min of irradiation. However, 97% of BPA was degraded in the presence of both H₂O₂ and Fe(II). Without light irradiation, no BPA degradation was observed even in the presence of Fe(II) and H₂O₂. These results show that photo-Fenton processes are effective in the natural attenuation of BPA in surface water. In addition, the presence of humic acids (HAs), which were of more aliphatic nature, resulted in enhancing BPA degradation via the photo-Fenton processes. Therefore, HAs can be one of the important factors in enhancing the degradation of BPA in surface water via the photo-Fenton processes.     

Thermodynamic investigation of the effect of oxygen and hydrogen chloride potential upon generation and decomposition behavior of dioxins

The thermodynamic equilibrium of the C‐H‐O‐Cl system has been calculated to elucidate the generation and decomposition behavior of dioxins, and is discussed from the viewpoint of the oxygen and hydrogen chloride potential. The dioxins behavior is greatly dependent on the oxygen potential, i.e. higher temperature and oxygen potential lead to the complete decomposition of dioxins, while low hydrogen chloride potential under insufficient oxygen condition leads to an increase of multi‐chlorine displacement of dioxins.     

软骨藻酸神经毒性作用机制研究进展

在拟菱形藻引发的有毒赤潮中产生的记忆缺失性贝毒(amnesic shellfish poison,ASP)软骨藻酸,经贝类等海洋生物摄入进入食物链,在对海洋生物造成危害的同时,也对人类健康造成威胁。软骨藻酸中毒者临床上表现为呕吐、腹痛和头痛等症状,严重者出现神经系统功能紊乱,如昏迷、抽搐和记忆缺失。软骨藻酸结构上与兴奋性氨基酸谷氨酸相似,它可以通过直接活化KA(kainate)受体和AMPA(α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)受体介导兴奋性神经毒。本文主要从线粒体功能紊乱、内质网应激和神经炎症等方面就软骨藻酸的神经毒性作用机制进行了综述。     

Ecological issues and risk assessment in China

As a result of economic development and population explosion, global ecological environments have been severely disturbed and markedly changed. An ecological crisis involving desertification, soil erosion, degradation of land quality, loss of biodiversity and global climate change has been brought about all over the world. In order to manage ecosystems efficiently, it is necessary to assess ecological risk at multiple scales. Ecological risk is the probability that a region and/or site will experience defined ecological or environmental problems. In this paper, the ecological risks of soil erosion, desertification, and acid deposition have been assessed on a national scale according to natural and human factors, such as topography, soil, vegetation and climate. This assessment has provided very useful information for ecological environmental management in China.     

Diversity,endemism and economic potential of wild edible plants of Indian Himalaya

SUMMARY

The rich plant diversity of the Indian Himalaya is utilized by the native communities in various forms as medicine, edible/food, fodder, fuel, timber, agricultural tools, etc. Among these, wild edible plants form an important source as a supplement/substitute food in times of scarcity for native communities. Because land holdings are small and subsistence agriculture prevails, the natives gather many wild plants for food. This paper presents an inventory of wild edible plants of Indian Himalaya used by local communities. Over 675 wild plant species, representing 384 genera and 149 families, are used as food/edible and their various parts are either consumed raw, roasted, boiled, fried, cooked or in the form of oil, spice, seasoning material, jams, pickles, etc. The species were analysed for diversity in different phytogeographical provinces, altitudinal distribution, endemism, origin and potentials. West Himalaya shows the highest diversity (50.96%) of edible plants and East Himalaya the maximum number of endemics (18 taxa) and wild relatives of economic plants (39 taxa). Mass scale propagation, dissemination of information packages to local inhabitants to ensure that wild edibles remain as a resource for income generation, and strategies for conservation and management are recommended.     

用钢管酸洗废水生产聚合硫酸铁技术的研究和应用

为了解决钢管酸洗废水污染环境和浪费资源难题,可用其生产聚合硫酸铁,从而实现循环经济。采用蒸发浓缩和催化聚合反应实现聚合硫酸铁的生成。其产品质量达《净水剂聚合硫酸铁》标准,可作为絮凝剂使用。研究和实践证明,用钢管酸洗废水制备聚合硫酸铁是可行的,具有明显的经济效益和环境效益,值得推广。     

Effects of citric acid on Cu（Ⅱ） and Cd（ Ⅱ ） adsorption ＆ desorption in calcareous cinnamon soil

通过室内培养和吸附-解吸实验,研究了不同柠檬酸含量土壤对Cu2＋、Cd2＋吸附-解吸的影响.结果表明,土壤对Cu2＋的吸附量随加入柠檬酸量的增加而明显增加,达到峰值后（柠檬酸含量为0.5 mmol.kg-1）,吸附量随柠檬酸含量的增加而下降,即Cu2＋的吸附曲线呈峰型.在低柠檬酸含量时,土壤对Cu2＋的吸附量受Cd2＋浓度影响较小,但随柠檬酸含量的增加,在低铜浓度处理（Cu2＋浓度为600 mg·L-1,Cu600）下,土壤对Cu2＋的吸附量随Cd2＋浓度的增大而增大,但在高浓度铜处理（Cu2＋浓度为1000 mg·L-1,Cu1000）下,土壤对Cu2＋的吸附量随Cd2＋浓度的增加而减少.Cu2＋的解吸量随柠檬酸含量的增加而总体上降低;相同柠檬酸含量下,Cu600处理下,Cd2＋浓度为10 mg·L-1（Cd10）条件下Cu2＋解吸量明显低于无Cd2＋（Cd0）和Cd2＋浓度为1 mg·L-1（Cd1）条件下.而Cu1000处理下,Cd2＋的浓度对Cu2＋解吸量的影响较小.Cd2＋吸附量随柠檬酸含量的增加无明显变化,但随Cu2＋浓度的增加下降明显,其中无Cu2＋处理Cd2＋吸附量极显著地高于Cu600和Cu1000处理,而Cu600和Cu1000处理间差异不显著,且土壤对Cd2＋的吸附随镉添加量增加而增加;Cd2＋的解吸量随柠檬酸含量的增加先增大后保持稳定,在柠檬酸含量为0.5 mmol.kg-1时达到最大,Cu600处理的Cd2＋的解吸量显著地高于Cu1000处理.