南湖水体多相介质中重金属元素的分布特征

以南湖水体中的水、沉积物、生物膜和悬浮物为研究对象,对重金属元素的分布与富集情况进行了研究.结果表明,不同采样点、不同相中Zn的含量最高,Cd的含量最低,但Cd的富集能力最强,生物膜和悬浮物富集重金属的能力远大于沉积物的富集能力,且Zn,Cu,Cd和Pb均表现出点源污染的特性;采用社会科学统计程序(SPSS)相关分析方法分析了重金属元素(Zn,Cu,Cd,Pb,Fe和Mn)在固相介质中的相互关系,结果显示,沉积物、生物膜和悬浮物中元素间的相关性趋势存在着一定差异,3种固相介质中Cd与Fe的相关系数均大于Cd与Mn的相关系数,而Pb与Fe的相关系数均小于Pb与Mn的相关系数,说明铁氧化物对镉环境化学行为的贡献大于锰氧化物,对铅环境化学行为的贡献小于锰氧化物.

清水灌溉对消除城郊稻田土壤PAHs污染的作用

为评价清水灌溉对消除城郊稻田土壤多环芳烃(PAHs)污染的作用,提供土壤PAHs污染的工程治理理论依据,以沈抚污水灌区为研究对象,采集连续清水灌溉0,3,10和30年的污染稻田0～20 cm和20～40 cm土层的土壤样本,测定PAHs各组分含量,分析清水灌溉对消除稻田土壤PAHs总量及某些单一组分的效果。当前沈抚污水灌区稻田土壤PAHs总量在表层为612.3～6362.8μg/kg.干土,在亚表层为319.5～4318.5μg/kg.干土。随着清水灌溉年限的增加,土壤PAHs总量和16种PAHs单一组分含量均不同程度逐渐降低。清水灌溉10年后,土壤PAHs总量接近或低于土壤PAHs环境标准;单一PAHs组分仅菲含量依然高出环境标准。清水灌溉措施可有效消除由污水灌溉所造成的土壤PAHs污染,特别是高环PAHs污染,但是其作用周期需要10年左右或更长的时间。

区域尺度降雨径流估算方法研究Ⅰ-算法设计

径流是区域水土流失的基础。基于已有试验研究和观测数据,结合GIS空间分析功能,初步提出了区域径流计算的基本思路,并对降雨径流产生的各个环节做出了算法设计,考虑的过程包括降水、植被截留、入渗、微地形存储、地表径流等。基于DEM将流域划分为规则网格并以此为基本计算单元,将月降水过程划分为若干时段作为计算迭代的基本单元,本算法可以计算出区域内每一网格单元任一时段末的地表径流量,为进一步建立区域水土流失模型奠定了基础。

日本菟丝子对寄主的选择行为

在野外对日本菟丝子(Cuscutajaponica)选择寄主的行为进行观察,结果表明,在所研究的植物群落中,日本菟丝子在不同寄主上发生缠绕的数量多少、发生吸器时间的先后和缠绕比率的大小顺序为枸树、蟛蜞菊、五爪金龙和马缨丹,而从缠绕发生至吸器发生期间日本菟丝子生长点伸长量的大小顺序则相反,且差异显著.日本菟丝子生长点在与聚氯乙烯塑料(PVC)棒接触后24h内发生明显的偏离,而在接触不同寄主后12h内则发生左旋3圈缠绕.多寄主共存的群落比单一寄主群落对日本菟丝子及其寄主的生存均有利.日本菟丝子选择寄主的行为与不同寄主N的含量关系不明显,推测这种选择行为与不同寄主次生物质的差异有关.

沈阳市城市扩展动态模拟与预测

基于遥感和GIS,采用SLEUTH模型对沈阳市辖区1988-2004年间的城市扩展过程进行动态模拟,对未来(2005-2030年)两种预案条件下的城市发展格局进行预测,即目前趋势预案和区域开发政策与城市规划预案。结果表明:到2030年,两种预案条件下,城市面积分别增加306.0km2和172.7km2,占土地总面积的百分比达到22.1%和18.3%。目前趋势预案条件下的未来城市发展格局比较分散;而区域开发政策与规划预案条件下,城市扩展格局将更加紧凑,充分体现了区域开发与保护政策、城市规划对城市扩展的约束和引导作用。

水土保持林土壤抗蚀性能评价研究

运用土壤有机质含量、水稳性团聚体含量、水稳性团粒平均重量直径、团聚度和分散系数等各项指标 ,对不同树种组成、不同林龄水土保持林的土壤抗蚀性能进行分析、评价 .结果表明 ,水土保持林对于提高土壤抗蚀性能具有重要作用 ,这种作用主要针对表层土壤而言 ;与油松纯林相比 ,油松阔叶树混交林土壤有机质含量较高 ,水稳性团聚体含量增加了 1.71%～ 3 8.5 3 % ;且随着林龄的增长 ,水土保持林土壤抗蚀性能不断增强 .

中国西南干旱河谷区植物多样性边界影响域的两种判定方法(英文)

研究了中国西南岷江上游干旱河谷区不同类型景观边界的影响域。共选取三种类型的边界。以植物多样性为基础,分别采用主成分分析法和移动窗口法对边界的影响域进行分析。结果表明,5条样带中,主成分分析法可以判定3条样带的影响域,而移动窗口法可以判定4条。两种方法均可判定边界的影响域,并且影响域均在距边界50m内。在林地样带两种方法可以得出相似的结论,但在花椒地样带中所得结论不一致。两种方法比较,移动窗口法更成功些。虽然两种方法各有利弊,但它们都是刻画边界动态的有力工具。图8表2参22.

中国纤孔菌属两新记录种

本文报道了中国纤孔菌属两个新记录种,分别为芮克纤孔菌Inonotus rickii (Pat.) D.A.Reid和杨生纤孔菌Inonotus plorans (Pat.) Bondartsev & Singer。芮克纤孔菌采于海南省保亭县热带植物园,生长在橡胶树上,杨生纤孔菌Inonotus plorans发现于中国西北地区的新疆,生长在杨树上,本文根据中国的材料对这两个种进行了详细描述和显微结构绘图。

Uncertainties in estimates of cropland area in China: a comparison between an AVHRR-derived dataset and a Landsat TM-derived dataset

The large uncertainties in estimates of cropland area in China may have significant implications for major cross-cutting themes of global environmental change-food production and trade, water resources, and the carbon and nitrogen cycles. Many earlier studies have indicated significant under-reporting of cropland area in China from official agricultural census statistics datasets. Space-borne remote sensing analyses provide an alternative and independent approach for estimating cropland area in China. In this study, we report estimates of cropland area from the National Land Cover Dataset (NLCD-96) at the 1:100,000 scale, which was generated by a multi-year National Land Cover Project in China through visual interpretation and digitization of Landsat TM images acquired mostly in 1995 and 1996. We compared the NLCD-96 dataset to another land cover dataset at I-km spatial resolution (the IGBP DIScover dataset version 2.0), which was generated from monthly Advanced Very High Resolution Radiometer (AVHRR)-derived Normalized Difference Vegetation Index (NDVI) from April, 1992 to March, 1993. The data comparison highlighted the limitation and uncertainty of cropland area estimates from the DIScover dataset. (C) 2003 Elsevier Science B.V. All rights reserved.

Direct electron transfer of horseradish peroxidase and its electrocatalysis based on carbon nanotube/thionine/gold composites

Horseradish peroxidase (HRP) was incorporated into multiwalled carbon nanotube/thionine/Au (MTAu) composite film by electrostatic interactions between positively charged HRP and negatively charged MTAu composite. The results of electrochemical impedance spectroscopy (EIS) confirmed adsorption of HRP on the surface of MTAu modified GC electrode.

novel blue-emitting long-lasting proyphosphate phosphor Sr2P2O7:Eu2+, Y3+

By introducing the Y3+ into Sr2P2O7:Eu2+, we successfully prepared a kind of new phosphor with blue long-lasting phosphorescence by the high-temperature solid-state reaction method. In this paper, the properties of Sr2P2O7:Eu2+, Y3+ were investigated utilizing XRD, photoluminescence, luminescence decay, long-lasting phosphorescence and thermoluminescence (TL) spectra. The phosphor emitted blue light that was related to the 4f(6)5d(1)-S-8(7/2) transition of Eu2+. The bright blue phosphorescence could be observed by naked eyes even 8 h after the excitation source was removed. Two TL peaks at 317 and 378 K related to two types of defects appeared in the TL spectrum. By analyzing the TL curve the depths of traps were calculated to be 0.61 and 0.66 eV. Also, the mechanism of LLP was discussed in this report.

Preparation of novel silver-gold bimetallic nanostructures by seeding with silver nanoplates and application in surface-enhanced Raman scattering

Novel silver-gold bimetallic nanostructures were prepared by seeding with silver nanoplates in the absence of any surfactants. During the synthesis process, it was found that the frameworks of silver nanoplates were normally kept though the basal plane of silver nanoplates became rugged. The real morphology of these nanostructures depended on the molar ratio of gold ions to the seed particles. When the molar ratio of gold ions to silver atoms increased from 0.5 to 4, porous or branched silver-gold bimetallic nanostructures could be made. The growth mechanism was qualitatively discussed based on template-engaged replacement reactions and seed-mediated deposition reactions. Due to the unusual structures, they exhibited interesting optical properties. Moreover, they were shown to be an active substrate for surface-enhanced Raman scattering measurements.

Suppression of phase separation in PC/PMMA blend film by thermoset oligomer

Phase separation of bisphenol A polycarbonate (PC) and poly(methyl methacrylate) (PMMA) thin blend film is suppressed by addition of solid epoxy oligomer. Epoxy has strong intermolecular interactions with both PC and PMMA, while PC and PMMA are quite incompatible with each other. Consequently, phase separation in the PC/PMMA blend film pushes epoxy to the interface; at the same time, PC and epoxy react readily at the interface to form a cross-linking structure, binding PMMA chains together. Therefore, the interface between PC and PMMA is effectively reinforced, and the PC/PMMA thin blend film is stabilized against phase separation. On the other hand, only an optimal content of epoxy (i.e., 10 wt %) can serve as an efficient interfacial agent. In contrast to the traditional reactive compatibilization, here we observed that the cross-linking structure along the interface is much more stable than block or graft copolymers. Atomic force microscopy (AFM) is used to characterize the morphological changes of the blend films as a function of annealing time. Two-dimensional fast Fourier transform (2D-FFT) of AFM data allows quantitative investigation of the scaling behavior of phase separation kinetics.