一株焦化废水降酚菌的质粒初步研究

从处理焦化废水的活性污泥池中,分离得到了一株具有降酚能力的细菌, Ｊ Ａ． Ｊ Ａ 可以在含酚的 Ｈ Ｐ 复杂培养基中生长,也可以在以酚为唯一碳源的 Ａ Ｂ Ｐ 培养基中生长,且具有产黑色素的特点．用碱裂解提取质粒的方法发现它含有一个质粒,定名为ｐ Ｘ Ｈ１ ,并测定了这个质粒的大小约为２ ．６ ｋｂ ．用限制性内切酶 Ｂｇｌ Ｉ和 Ｒｓａ Ｉ进行双酶切,作出了初步的物理图谱．ｐ Ｘ Ｈ１ 经过２０ 次没有酚作为选择压传代培养后仍然能１００ ％ 保留,同时, Ｊ Ａ菌仍具有降酚能力,表明其具有很高的遗传稳定性     

Anuran Development, Density and Diversity in Relation to Agricultural Activity in the Holland River Watershed, Ontario, Canada (1990–1992)

Significantly lower anuran species diversity and density was recorded in a vegetable growing area relative to upstream and downstream sites in the Holland River watershed, Ontario, Canada. Egg hatching success and tadpole deformity rates of American toads (Bufo americanus americanus), green frogs (Rana clamitans melanota) and northern leopard frogs (Rana pipiens) eggs in water from field sites and control water were assessed. Compared to the control and the upstream site, the total abnormality rate (unhatched eggs plus deformed tadpoles) was higher for American toads in water from the agricultural and downstream sites. Total abnormality was higher in green frog eggs in water from the agricultural site and a downstream site. Trace concentrations of organophosphorus pesticides were detected most often in agricultural zone water and sediments than in upstream and downstream sites. Organochlorine pesticide residues, especially in agricultural zone samples, exceeded the no effect level guidelines for the protection of aquatic life. Ammonia, phosphorus, particulates, BOD and TKN were highest in the agricultural zone. Significant correlations between these parameters and anuran development suggest nutrient run-off as a causal or contributing factor in lower anuran diversity, density and reproductive success of American toads and green frogs in the site dominated by agriculture.     

基于遗传算法进行EMI滤波器电感的设计

通过电感的高频特性及其对共模插入损耗的影响分析,采用遗传算法和Ngspice仿真库设计出电感的选择方案,最后通过电路仿真和实验同时验证方案的有效性。该方案避免了对EMI滤波器高频段的复杂建模,降低了电感选择的难度,对电感元件的选择具有一定的指导意义。     

石油污染地下水中细菌多样性研究

采集了某废弃炼油厂的石油污染地下水样品,提取水中微生物总DNA,构建细菌16S rDNA克隆文库,并通过16S rDNA序列的系统发育分析,对样品中的细菌种群多样性以及群落结构进行了研究.结果表明,文库中阳性克隆的16S rDNA序列分属10个细菌类群,分别为γ-Proteobacteria(49.1%)、α-Proteobacteria(12.9%)、β-Proteobacteria(11.1%)、Bacteroidetes(9.2%)、Verrucomicrobia(6.7%)、Acidobacteria(2.5%)、δ-Proteobacteria(1.2%)、Actinobacteria(1.2%)、Planctomycetes(0.6%)、Unidentifiedbacteria(5.5%).在这一生态系统中,γ-Proteobacteria类细菌占据主导地位,接近50%,尤其是假单胞菌属(Pseudomonas)微生物在文库中的比例达35.6%.该石油污染地下水样品中细菌与许多其它已知的降解菌亲缘关系较近,如鞘胺醇单胞菌(Sphingomonas)、红球菌(Rhodococcus)和短波单胞菌(B...     

生计多样性对农户参与农田生态补偿政策响应状态的影响——以上海闵行区、苏州张家港市发达地区为例

农田生态补偿政策是采用经济手段激励农户对农田生态系统服务功能进行保育和维护,解决因市场失灵造成生态效益外溢的一种有效方式,对于改善农田生态环境、提升农地开敞空间、增加农户收益具有积极作用。论文从发达地区农户生计多样性角度入手,利用结构方程模型分析农户生计多样性对农户参与补偿政策的支持意愿、政策实施效果响应的影响。结果表明:①农户基本特征、家庭特征、生计多样性特征、村庄发展特征在5%的水平下对农户在农田生态补偿政策上的支持意愿具有正向影响;②农户基本特征、家庭特征、生计多样性特征在5%的水平下对农户在补偿政策实施效果上的响应具有正向影响,农户村庄发展特征在5%的水平下对其具有负向影响;③农户生计多样性特征是影响农户补偿政策支持意愿最主要的因素,是影响补偿政策实施效果响应的次要因素。这表明补偿政策实施后,农户生计多样性特征对于提高农户对补偿政策支持意愿与政策实施效果响应方面具有积极的作用。把握三者之间的关系有利于政府制定和完善现有农田生态补偿政策,为引导农户生计多样性发展提供参考。     

物种多样性对植物生长与土壤镉污染修复的影响

土壤重金属污染是当今最为突出的环境问题之一,其中,重金属镉(Cd)已成为我国受污染土壤中最主要的无机污染物之一.植物修复法是去除土壤重金属的重要方法,研究表明,植物物种多样性的增加能促进生态系统功能.那么在Cd污染土壤中,植物物种多样性对植物生长和Cd污染修复会有怎样的影响,其内在机理是怎样的并不清楚.基于此,本研究选择6种本地常见草本植物(荆芥、鸡眼草、短叶水蜈蚣、牛筋草、鸭跖草和细风轮菜),通过室内控制实验研究不同植物物种多样性(1-,2-,3-,6-物种)对植物生长与土壤Cd污染修复的影响.结果表明:植物物种多样性的增加显著促进植物地下生物量和总生物量的积累,并对植物根系形态(根总长、根总表面积、根尖总数与根平均直径)和叶绿素荧光参数(PSII最大光能转化效率F_v/F_m和PSII潜在活性F_v/F_0)有显著的促进作用;植物物种多样性的增加能显著提高植物地上、地下及总Cd含量(积累量)和富集系数;植物物种多样性的增加对植物生长、根系形态指标及Cd的富集具有显著的净效应,且以互补效应为主.本研究选取的是对环境条件要求不高、生长周期短的本地草本植物,可为利用本地常见短世代周期植物进行土壤重金属污染修复提供理论依据.     

黄河三角洲贝壳海岛与植物多样性保护

根据1997－1999年调查，查清了黄河三角洲贝壳岛资源状况，研究了其高等植物物种多样性、植被类型、植物区系组成特点，分析了近年来因乱采滥挖贝壳资源对贝壳海岛和植物多样性破坏现状，提出了保护贝壳海岛和和植物多样性的对策与建议。     

Degradation of Populus euphratica community in the lower reaches of the Tarim River, Xinjiang, China

IntroductionRiparian systems are aquatic-terrestrial ecotones withunique biotic , biophysical and landscape characteristics(Gregory, 1991 ; Naiman, 1997 ; Wiens , 2002) and areshaped by fluvial geomorphic processes . Riparian plantcommunities perform an i…     

高原高寒污水处理系统的微生物群落特征

为研究高原高寒污水处理系统活性污泥的微生物群落结构及多样性,以拉萨、云南、四川的3座高原污水厂作为实验组,同时以重庆2座非高原污水厂作为对照,采用PCR-DGGE技术对比分析了高原与非高原污水厂的微生物特性.研究表明:高原污水厂样品与非高原样品在聚类中展现出了较为疏远的关系,微生物群落区别明显.受强紫外线辐照的抑制,高原高寒污水处理系统微生物多样性的平均水平显著低于非高原污水厂,较低的微生物多样性是导致高原高寒地区污染物去除效果不佳的一项重要原因.群落构成方面,共鉴定出16个优势菌属,对应Proteobacteria、Bacteroidetes、Firmicutes、Verrucomicrobia4个门.组间差异分析结果发现,高原组中丰度显著偏高的菌属只有Prosthecobacter,该菌在污水厂内分布广泛,且能够适应高原低温的条件.对于大多数活性污泥微生物而言,高原强紫外线是不利的生存条件.因此,减少高原露天污水处理系统的紫外辐照,是提升污水处理效能的一个潜在措施.     

Total nitrogen and community turnover determine phosphorus use efficiency of phytoplankton along nutrient gradients in plateau lakes

Numerous studies support that biodiversity predict most to ecosystem functioning, but whether other factors display a more significant direct impact on ecosystem functioning than biodiversity remains to be studied. We investigated 398 samples of the phytoplankton phosphorus resource use efficiency (RUE_P = chlorophyll-a concentration/dissolved phosphate) across two seasons in nine plateau lakes in Yunnan Province, China. We identified the main contributors to phytoplankton RUE_P and analyzed their potential influences on RUE_P at different lake trophic states. The results showed that total nitrogen (TN) contributed the most to RUE_P among the nine lakes, whereas community turnover (measured as community dissimilarity) explained the most to RUE_P variation across the two seasons. Moreover, TN also influenced RUE_P by affecting biodiversity. Species richness (SR), functional attribute diversity (FAD2), and dendrogram-based functional diversity (FDc) were positively correlated with RUE_P in both seasons, while evenness was negatively correlated with RUE_P at the end of the rainy season. We also found that the effects of biodiversity and turnover on RUE_P depended on the lake trophic states. SR and FAD2 were positively correlated with RUE_P in all three trophic states. Evenness showed a negative correlation with RUE_P at the eutrophic and oligotrophic levels, but a positive correlation at the mesotrophic level. Turnover had a negative influence on RUE_P at the eutrophic level, but a positive influence at the mesotrophic and oligotrophic levels. Overall, our results suggested that multiple factors and nutrient states need to be considered when the ecosystem functioning predictors and the biodiversity-ecosystem functioning relationships are investigated.