渗滤液中胶粒的梯度分离

用系列滤膜对老港填埋场的新鲜渗滤液、1991年垃圾产生的渗滤液进行了梯度分离, 并研究了COD、氨氮、TS、DS、电导率和pH的变化趋势与不同孔径膜之间的关系.结果表明:随着系列膜孔径的减小, 经过膜的梯度分离后, 出水COD、氨氮、DS值逐渐减少, 但减少的幅度并不一样, 电导率先减小后增加, pH则先增加后减小.     

短程硝化工艺出水水质及微生物区系分析

实验采用短程硝化工艺处理高氨氮废水,并用PCR-DGGE分析了系统中的微生物区系。结果表明,进水氨氮浓度在50～400mg/L之间梯度增加时,出水氨氮浓度在10mg/L以下;随着氨氮浓度的增加,亚硝态氮积累率逐渐升高,当氨氮浓度达到300mg/L时,积累率达到90%左右。DGGE分析结果表明,随着运行时间的延长,微生物区系多样性减少;氨氮负荷为50mg/L与400mg/L相比,相似性为0.24。     

硝化悬浮填料塔中氨氧化细菌群落稳定性特征分析

利用PCR-DGGE分析技术,对于化学生物絮凝处理工艺中悬浮填料塔的氨氧化细菌(AOB)群落进行了研究。主要考察了曝气强度和水力停留时间2个运行参数调整的情况下,系统AOB群落结构的变化。生物膜样品直接取自硝化填料塔,多维尺度(MDS)方法用于DGGE电泳图谱的分析,分析结果以二维图形向量的方式显示,结果表明,曝气强度和水力停留时间均对AOB群落有一定的影响,主要的AOB种类在运行过程中基本不变,系统对于运行条件具有良好的稳定性。     

The geographical distribution of plant latex

Summary Latex is a widespread defence in plants against natural enemies and a literature-based summary of latex-producing angiosperms shows records in 40 families, and more than 20,000 species are estimated to bear laticiferous structures of some kind. This is considerably higher than the usually quoted figure of 12,500 species. There are more tropical than temperate latex-bearing families, both in absolute numbers and proportionally. Proportions of latex-bearing families are similar both in tropical and in more widespread or cosmopolitan families. Significantly more latex-bearing species belong to tropical than either to temperate or to widespread taxa, both in absolute and in relative terms. These differences may be related to the higher diversity of natural enemy species and to higher rates of herbivory in the tropics.     

基于PCR-DGGE的重金属污染土壤微生物种群指纹分析

采用变性梯度凝胶电泳（DGGE）分析方法,研究沈阳市细河沿岸重金属污染土壤中微生物结构多样性、种群丰富度及种群结构的动态变化规律。结果表明：直接从土壤中抽提总DNA,对16SrRNAV3可变区序列进行扩增,DGGE指纹图谱分析,微生物种群结构和变化规律明显,同时也表现为重金属污染程度越重,多样性指数越低;其中细河底泥重金属含量严重超标,多样性指数最低。经方差分析,重金属污染情况与Shannon-wiener多样性指数呈负相关,其中重金属污染对微生物的均匀度指数影响最显著,并且锌污染对其影响最大为-0.985。表明PCR-DGGE技术可以用于污染环境下微生物多样性研究,也为污染环境下土壤微生物多样性研究提供了新的实验方法与依据。     

某生活垃圾卫生填埋场渗滤液的梯度分离与表征

目前,渗滤液中污染物的粒度分布及其在渗滤液污染控制中的作用日益受到关注。通过系列微滤膜(1.2μm及0.45μm)对某生活垃圾卫生填埋场渗滤液各处理单元的渗滤液进行梯度分离,发现悬浮物对COD、浊度的影响较大;COD主要在胶体态和可溶解态间分配,不同渗滤液中的分配情况不同;磷主要与胶体、悬浮物以各种形式结合而存在;细胶粒和溶解态等小分子对TN的贡献大;不同粒度物质对pH的影响不明显;总残渣在可溶态组分中所占比例较大。膜微滤处理渗滤液可以有效的去除一部分物质,使COD、TP、TN、浊度、电导率都有不同程度的降低,pH逐渐升高,但对总N、残渣的去除效果不好。     

中国高山及高原边缘过渡区环境中持久性有机污染物研究进展

根据近十年的国内外文献报道,本文系统介绍了目前中国高山及高原边缘过渡区环境中持久性有机污染物（POPs）研究进展,内容涉及大气、降水、土壤等介质,重点对表层土壤中典型POPs沿海拔高度的分布进行了阐述和讨论.由于影响因素众多,在不同地理位置和气象条件下,\"高山冷凝效应\"表现不同.本文对比了中国南方、北方以及西南地区高山表层土壤中典型POPs的观测数据并与Mountain-POP模型进行了比较.Mountain-POP模型对海拔2500 m以下多雨且植被丰富的高山体现出来一些规律性,但对降水少、海拔高度大于2500 m的荒原型土壤则有其应用的局限性.因此在应用于具体的高海拔地区时,要将化合物的物化性质与局地气象、地形、植被等环境特点相结合进行考虑.高海拔高山与高原有不同的机理和归宿.根据POPs大气沉降可能受到的影响,可将高山和高原区分为\"海拔梯度降水型\"和\"极地型\"两类.本文提出了在此领域存在的问题和发展方向.     

Testing hypotheses on shape and distribution of ecological response curves

Niche theory with hypotheses on shape and distribution of ecological response curves is used in the studies of resource sharing of competing plant species. Predictions based on theory should be applicable when, e.g., effects of competing species on the ecological tolerances are assessed or species’ diversity along a resource gradient is evaluated. We studied the ecological response curves of competing plant species along a resource gradient in boreal forests. The study was based on nation-wide soil and vegetation data collected from 455 sample plots on boreal forests in Finland. Species response curves along a soil fertility gradient (in terms of C/N ratio) were estimated using generalized additive models. Distribution of species optima and the relationship of niche width and skewness to the location of the optimum were analyzed with new bootstrap tests. The developed tests can account for the effects of truncation observed in the response curves of several species and for the uneven distribution of observations on the gradient.The estimated response curves of the major field layer species of boreal forests were not evenly distributed along soil C/N gradient. The density of optima peaked with relatively high nitrogen availability. Species with optima at low nitrogen availability had relatively broad realized niches. Niche width was negatively correlated with the density of optima. Species optima were packed and niches were narrow at high resource levels. This result suggests that a greater number of more specialized species can occur and interspecific competition decreases niche widths at high resource levels. Species were packed in the gradient where the C/N ratio was lower than 25, i.e., in conditions where nitrification can take place. This indicates that the majority of the vascular plants of boreal forests are favoured by the availability of NO₃⁻. Those few species thriving at high C/N ratios have broader realized niches.