新疆外来入侵种现状研究

通过对我国新疆9种已呈现出较大危害的外来入侵种的分布范围、生境类型、种群建立状况、起源、首次发现或引入的地点及时间、来源、引入路径、入侵途径、经济和生态影响等内容进行了研究,并深入分析了目前外来入侵种管理等方面存在的问题,提出了外来入侵物种预防、控制和管理措施。     

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management.     

Thioarsenate formation upon dissolution of orpiment and arsenopyrite

Thioarsenates were previously determined as dominant species in geothermal and mineral waters with excess sulfide. Here, we used batch leaching experiments to determine their formation upon weathering or industrial leaching of the arsenic-sulfide minerals orpiment (As₂S₃) and arsenopyrite (FeAsS) under different pH and oxygen conditions. Under acidic conditions, as expected based on their known kinetic instability at low pH, no thioarsenates formed in either of the two mineral systems. Under neutral to alkaline conditions, orpiment dissolution yielded mono-, di- and trithioarsenate which accounted for up to 43-55% of total arsenic. Thioarsenate formation upon arsenopyrite dissolution was low at neutral (4%) but significant at alkaline pH, especially under suboxic to sulfidic conditions (20-43%, mainly as monothioarsenate). In contrast to orpiment, we postulate that recombination of arsenite and sulfide in solution is of minor importance for monothioarsenate formation during alkaline arsenopyrite dissolution. We propose instead that hydroxyl physisorption lead to formation of As-OH-S surface complexes by transposition of hydroxyl anions to arsenic or iron sites. Concurrently formed ironhydroxides could provide re-sorption sites for the freshly released monothioarsenate. However, sorption experiments with goethite showed slower sorption kinetics of monothioarsenate compared to arsenite, but comparable with arsenate. The discovery that thioarsenates are released by natural weathering and industrial leaching processes and that, once they are released, have a higher mobility than the commonly-investigated species arsenite and arsenate requires future studies to consider them when assessing arsenic release in sulfidic natural or mining-impacted environments.     

In vitro toxicity of fungicides with different modes of action to alfalfa anthracnose fungus,Colletotrichum destructivum

Abstract

Sensitivity of 24 isolates of Colletotrichum destructivum O’Gara, collected from alfalfa plants in Serbia, to eight selected fungicides, was investigated in this study. Molecular identification and pathogenicity test of isolates tested were also performed. Fungicide sensitivity was evaluated in vitro, using mycelial growth assay method. All isolates exhibited significant pathogenicity, causing necrosis at the alfalfa seedling root tips two days after inoculation. Using the primer pair GSF1-SR1 and by comparing the amplified fragments of the tested isolates with the marker (M), the presence of the amplicon of the expected size of about 900?bp was determined for all isolates. The isolates tested in this study showed different sensitivity towards fungicides in vitro. Mycelial growth was highly inhibited by QoI (quinone outside inhibitors) fungicide pyraclostrobin (mean EC₅₀=0.39?µg mL^?1) and by DMI (demethylation-inhibiting) fungicide tebuconazole (mean EC₅₀=0.61?µg mL^?1), followed by azoxystrobin (mean EC₅₀=2.83?µg mL^?1) and flutriafol (mean EC₅₀=2.11?µg mL^?1). Multi-site fungicide chlorothalonil and MBC (methyl benzimidazole carbamate) fungicide thiophanate-methyl evinced moderate inhibition with mean EC₅₀=35.31 and 62.83?µg mL^?1, respectively. Thirteen isolates were sensitive to SDHI (succinate dehydrogenase inhibitors) fungicide boscalid and fluxapyroxad, (mean EC₅₀=0.49 and 0.19?µg mL^?1, respectively), while the rest of isolates were highly resistant.     

松树锯末对亚甲基蓝（MB）的吸附研究

采用松树锯末以及改性松树锯末对模拟废水中的亚甲基蓝进行吸附实验研究。研究结果表明,当亚甲基蓝的初始浓度为50 mg/L、pH为6、锯末投加量为1 g/L时,改性前后的锯末对亚甲基蓝的吸附量最大,分别为29.9 mg/g和60.6 mg/g。同时,对改性前后的锯末做了吸附等温线拟合及动力学研究。结果表明,吸附等温线均能很好地符合Langmuir吸附模式,吸附过程符合拟二级动力学方程。     

基于人工蜂群算法与BP神经网络的水质评价模型

针对BP网络水质评价模型的不足,引入人工蜂群(ABC)算法,将求解BP神经网络各层权值、阀值的过程转化为蜜蜂寻找最佳蜜源的过程,提出了一种新的结合人工蜂群算法的BP网络水质评价方法(ABC-BP)。并以2000—2006年渭河监测断面的10组实测数据作为测试样本对其水质进行了评价,实验结果表明该方法得到的水质评价结果准确,并具有很强的稳定性和鲁棒性。     

西安市城市主干道路面径流初期冲刷效应

以西安市城市主干道南二环太白路高架桥为路面径流采样区域,采用人工等时间间隔采样方法,在桥梁排水立管对2010年9—11月的3场径流事件进行全程采样,测试径流过程SS、COD、溶解性COD、NH3-N、Pb、溶解性Pb、Zn和溶解性Zn的浓度变化,研究路面径流的初期冲刷效应及其影响因素。结果表明,西安市城市主干道路面径流污染严重,降雨数小时后的末期径流仍具有较高的污染水平;径流过程污染物浓度变化规律与其赋存形态有关,SS、COD、Pb等以颗粒态为主的污染物的浓度随雨强变化剧烈波动,NH3-N、溶解态COD、溶解态Zn等以溶解态为主的污染物浓度变化受雨强影响较小,随径流过程呈逐渐减小趋势;路面径流初期冲刷现象并非普遍存在,与污染物的赋存状态和场次降雨特征密切相关,溶解态污染物易于出现初期冲刷现象,颗粒态污染物是否出现初期冲刷与场次降雨特征有关;测试的3场径流事件初期30%的径流携带的SS、COD、溶解性COD、NH3-N、Pb、Zn和溶解性Zn的负荷占场次径流总负荷的比例分别为21.8%～50.0%、25.5%～49.3%、36.3%～52.6%、52.6%～66.7%、26.8%～45.0%、27.2%～63.4%和36.2%～62.6%,表明仅对初期径流进行治理无法实现对西安市路面径流污染的有效控制。     

西安市及周边地区MODIS气溶胶光学厚度与PM10浓度关系模型研究

西安是空气污染监控和防治有代表性的西部大型城市。研究了西安市及周边地区上空气溶胶光学厚度与PM10浓度的关系模型。利用2011—2012年MODIS卫星气溶胶光学厚度（AOD）遥感产品,通过数据匹配,利用地面气象观测站点的能见度数据和相对湿度数据对AOD产品进行垂直标高订正和湿度订正,2项订正显著提高了AOD和地面PM10浓度的相关性,相关系数从0．36提高到0．65,按季节分类统计和订正春至冬四季的相关系数分别为0．57、0．71、0．62和0．87,夏季和冬季的订正更为有效,可用性更高,这可能由于受到不同季节气溶胶来源和特征的影响。为研究中国西部大型城市,特别是西安市空气环境监测和区域联防联控提供了一种有效方法。     

3种运行模式下CAST工艺脱氮性能

以模拟城市污水为处理对象,采用循环式活性污泥法（CAST）反应器,对3种运行模式（M1：常规模式,M2：缺氧好氧模式、M3：缺氧好氧交替模式）下系统的脱氮性能进行了研究,比较了各模式下CAST反应器的氨氮和总氮的去除效率,并对各模式下典型周期内氮基质浓度变化进行了考察,以确定系统的脱氮模式。结果表明,在氨氮去除不成为限制条件（去除率〉90％）的条件下,3种运行模式下系统总氮的平均去除率分别为67．3％、70．6％和82．4％,以缺氧好氧交替模式下的最高;M1、M2和M3均可实现亚硝酸型硝化,但随着温度的升高,亚硝酸型硝化逐渐消失。静态实验分析表明,3种模式下系统的氨氧化速率大小次序为：vN：M1〉vN：M2〉vN：M3,反硝化速率大小次序为：vDN,M2〉vDN,M3〉vDN,M1。