Molecular diversity of arbuscular mycorrhizal fungi at a large-scale antimony mining area in southern China

Arbuscular mycorrhizal fungi(AMF) have great potential for assisting heavy metal hyperaccumulators in the remediation of contaminated soils. However, little information is available about the community composition of AMF under natural conditions in soils contaminated by antimony(Sb). The objective of this study was to investigate the characteristics of AMF molecular diversity, and to explore the effects of Sb content and soil properties on the AMF community structure in an Sb mining area. Four Sb mine spoils and one adjacent reference area were selected from around the Xikuangshan mine in southern China. The association of AMF molecular diversity and community composition with the rhizosphere soils of the dominant plant species was studied by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis(PCR-DGGE). Results from all five studied sites showed that the diversity of AMF decreased with increasing Sb concentration. Principal component analysis(PCA) indicated that the AMF community structure was markedly different among these groups. Further redundancy analysis(RDA) showed that Sb contamination was the dominating factor influencing the AMF community structure in the Sb mine area. However, the multivariate analysis showed that, apart from the soil Sb content, extractable nitrogen content and organic matter content also attributed to AMF sequence distribution type. Some AMF sequences were only found in the highly contaminated area and these might be ideal candidates for improving phytoremediation efficiency in Sb mining regions. Gene sequencing analysis revealed that most species were affiliated with Glomus, suggesting that Glomus was the dominant AMF genus in the studied Sb mining area.     

海河干流浮游植物调查及环境影响因子研究

为研究海河干流汛期富营养化状况,于2013年8月对海河干流进行了浮游植物调查和水质监测,并采用冗余分析(RDA),研究了浮游植物群落与环境因子的关系.结果表明,浮游植物共计5门37种(属),优势种为水华微囊藻(Microcystis flos-aquae)、微小色球藻(Chroococcus minutus)、颤藻属(Oscillatoria sp.)、钝顶螺旋藻(Spirulina platensis)和梅尼小环藻(Cyclotella meneghiniana).浮游植物丰度范围为583.00～12 021.00×104 cells·L-1,生物量范围为4.01 ～45.70 mg·L-1,以蓝藻为主,海河干流处于重富营养状态.RDA分析结果表明,硝酸盐氮是显著影响海河干流浮游植物丰度变化的主要环境因子.控制营养盐的输入是防治海河干流蓝藻水华的主要措施.     

退化梭梭林禁牧封育周期的研究

对阿拉善荒漠地区不同时间（2005年、2002年、1999年和1980年）禁牧围封梭梭生态特征进行了对比研究。生态特征分析表明7年封育梭梭恢复效果最好,梭梭盖度达到了22．6％,密度增加到每公顷594株,生物量提高到每公顷12．01吨。而25年围封梭梭林密度、盖度和生物量均低于7年封育。年龄结构分析表明1年、4年和7年禁牧封育梭梭均发展趋势,而25年禁牧封育梭梭呈现衰退趋势。动态模拟分析表明通过禁牧封育,干旱区退化梭梭林恢复最佳周期14年,生物量达15．3吨／公顷,盖度28％,密度高达770彬公顷。     

美人蕉根系对不同基质结构水平潜流人工湿地水力特性的影响

为了研究植物根系对不同基质结构潜流人工湿地水力特性的影响,根据填料渗透系数,分别设置单层及多层基质结构潜流人工湿地小试实验系统,以美人蕉作为湿地植物,在植物栽种前与成熟后对两系统分别开展示踪试验研究.实验结果表明,美人蕉根系对于单层结构人工湿地水力特性有较明显的改善作用,有效体积从0.49提高到了0.53,短路值由0.60降低到0.41,水力效率提高最大由43%提高到59%.比较而言,植物根系对多层结构湿地有效体积和短路值有轻微负面影响,而对水力效率则有明显的改善作用(由64%提高到83%).此外,植物成熟后,两人工湿地系统中示踪剂回收率均有所下降,其中,单层结构湿地降低较显著,回收率由72%降到62%.可见,植物根系对系统水力特性有较大影响,应在人工湿地设计过程中给予考虑.     

铅锌矿区蜈蚣草内生放线菌的多样性及群落结构

为了认识重金属累积对植物内生菌的影响,采用变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术及序列分析对四川汉源铅锌矿区蜈蚣草内生放线菌的多样性进行了研究,并分析了内生放线菌多样性与Pb、Zn、Cu和Cd等主要重金属之间的相互关系.结果表明,蜈蚣草不同部分内生放线菌的群落结构和多样性存在一定的差异,多样性指数在2.79~3.29之间,与其他非重金属污染环境植物内生放线菌的多样性指数相似,说明在重金属污染地区仍然存在较为多样的内生放线菌类群.相关分析表明,蜈蚣草内生放线菌多样性指数与Cu、Cd和Pb的含量之间存在显著负相关.DGGE条带序列系统发育显示,链霉菌(Streptomyces)、假诺卡氏菌(Pseudonocardia)、小单孢菌(Micromonospora)、Xianggella为蜈蚣草内生放线菌优势类群,拟诺卡氏菌(Nocardiopsis)、小双孢菌(Microbispora)、马杜拉放线菌(Actinomadura)、弗兰克氏菌(Frankia)以及一些未培养放线菌也在蜈蚣草中存在.研究表明铅锌矿区蜈蚣草内生放线菌存在丰富的多样性,重金属的累积影响了内生放线菌的分布.     

A comparative study on the alternating mesophilic and thermophilic two-stage anaerobic digestion of food waste

An alternating mesophilic and thermophilic two stage anaerobic digestion(AD) process was conducted. The temperature of the acidogenic(A) and methanogenic(M) reactors was controlled as follows: System 1(S1) mesophilic A-mesophilic M;(S2) mesophilic A-thermophilic M; and(S3)thermophilic A-mesophilic M. Initially, the AD reactor was acclimatized and inoculated with digester sludge. Food waste was added with the soluble chemical oxygen demand(SCOD) concentrations of41.4–47.0 g/L and volatile fatty acids of 2.0–3.2 g/L. Based on the results, the highest total chemical oxygen demand removal(86.6%) was recorded in S2 while S3 exhibited the highest SCOD removal(96.6%). Comparing S1 with S2, total solids removal increased by 0.5%; S3 on the other hand decreased by 0.1 % as compared to S1. However, volatile solids(VS) removal in S1, S2, and S3was 78.5%, 81.7%, and 79.2%, respectively. S2 also exhibited the highest CH4 content, yield, and production rate of 70.7%, 0.44 L CH4/g VSadded, and 1.23 L CH4/(L·day), respectively. Bacterial community structure revealed that the richness, diversity, evenness, and dominance of S2 were high except for the archaeal community. The terminal restriction fragments dendrogram also revealed that the microbial community of the acidogenic and methanogenic reactors in S2 was distinct. Therefore,S2 was the best among the systems for the operation of two-stage AD of food waste in terms of CH4production, nutrient removal, and microbial community structure.     

北京市北神树生活垃圾填埋场产甲烷菌的群落结构和演替规律

产甲烷菌是填埋场稳定化的关键微生物.以北京市北神树垃圾填埋场为采样地,钻井采集了填埋深度6~36.1 m,填埋时间2~15 a的垃圾样品.采用PCR检验其中产甲烷菌的种类,并基于QPCR技术获得的数据,研究了各类产甲烷菌随时间和深度的数量变化,及其与垃圾化学性质之间的关系.发现堆体内有机质含量基本稳定,p H呈弱碱性,符合产甲烷阶段的化学特性.检测出两类乙酸营养型产甲烷菌(Methanosaeta和Methanosarcina),一类氢营养型产甲烷菌(Methanobacterials).随着填埋时间的延长,产甲烷菌呈现出先升高后下降的趋势,填埋9 a以上的垃圾中产甲烷菌群落结构趋于稳定.乙酸营养型的Methanosarcina为优势类群.三类产甲烷菌的含量与挥发性脂肪酸含量显著相关,与各类大分子有机质含量相关性很弱或不相关,表明产甲烷菌的数量受底物含量的影响,而在填埋2 a以上的垃圾中,大分子水解、发酵等作用对产甲烷菌影响微弱.     

基于HR/CFD技术的城市汽车尾气扩散规律研究

为研究城市空间结构对汽车尾气扩散规律,根据高分辨率遥感影像建立了某城市核心区域几何模型。以当地常年气象风向作为重要的边界条件之一,应用CFD多相流技术,模拟了十字交叉口车辆队列怠速等候35,45,55 s时的尾气扩散过程,并对45 s时4个监测点的体积分数进行了实测,最后,通过建筑高度优化,降低了该区域的尾气含量。以上研究结果表明:在空间狭小区域,近地空间CO体积分数达1.0×10-7,与研究域平均体积分数相差100倍以上,说明城市空间结构对尾气扩散影响较大,仿真所揭示的规律与实测吻合。建筑设计时应结合当地气象风向和风速,应设计一定的建筑高度梯度,可以促使污浊气体迅速扩散至远地空间。     

Dynamics of abundance and population structure of sea otters, <Emphasis Type="Italic">Enhydra lutris</Emphasis> L., on the Commander Archipelago and activity of their migrations between Islands

Fluctuations in the abundance of insular groups of sea otters on the Commander Archipelago are analyzed with regard to changes in meteorological conditions. The main factors responsible for the abrupt decline of the Bering Sea group between 2002 and 2004 are discussed. A statistically significant correlation has been revealed between fluctuations of sea otter abundance and the cycles of solar activity in the period since 1992. Changes in the age and sex structure of the insular groups of sea otters are evaluated.     

Energy-Saving Effect Calculation and Implementation Strategy Study on the Industrial Structure Adjustment in Western China

The western region is an important strategic base of energy in China. The average per capita possession of fossil energy in the west is twice that in China. On the basis of the analysis of the mechanism how industrial structure adjustment affects energy consumption per unit of gross domestic product (GDP), the energy input-output table of western China was designed and compiled. Combining multiobjective planning techniques, setting energy-saving, economic growth, and laborer's income growth as the goals, setting basic input-output relations, production capacity, and labor as the constraints, the multiobjective optimization model of western energy input-output was constructed. The results of industrial structure optimization of western China show that: with technology and product price remaining unchanged, the adjustment of the industrial structure can reduce energy consumption per unit GDP by 2.7%, at the same time ensuring the average annual increase of GDP and laborer's income of western region in excess of 8%. It indicates that industrial structure adjustment is an effective method in accomplishing the aim of energy saving. Finally, policy suggestions from four angles, such as industrial chain and financial policies, were put forward.