Mechanisms of copper tolerance by Armeria maritima in Dolfrwyong Bog,north Wales--initial studies

Preliminary field studies were carried out at Dolfrwynog Bog in July 2000. Replicate samples of water, Armeria maritima plants and the soils adhering to its roots were collected and analysed for copper. Concentrations of up to 6486 mg kg^–1 of copper in the soils were recorded. Accumulation of copper by the plant as expressed by concentration factors (CF) show that it is acting mainly as a copper excluder. Of the copper that is taken up, most of it is retained within the roots with very little being transported to the shoots of the plant. Moreover, a further possible mechanism of tolerance is exhibited by the excretion of copper through its decaying leaves. Towards the use of in vitro cultures to study the copper tolerance mechanisms in A. maritima a micropropagation protocol has been developed. The ex vitro plants have been rooted and established in compost.     

栽种沙枣以改善黄河三角洲地区生态环境

胜利油田位于我国黄河三角洲地区，潜水位高，水的矿化度大。生态环境恶劣，对植物尤其对木本植物的生长不利，整个地区生长的多是抗盐碱能力强的草本植物。针对油田的特殊环境条件，综合有关资料，介绍了以沙枣为代表的植物特性，特别强调了其抗盐碱、降低土壤矿化度和潜水位、增加土壤有机质和引起植被变化的特性。指出黄河三角洲也有些土质较好的、适于作物和木本植物生长的地区，改良盐碱地可以以这些地区为基点，放射性地向外逐步试验沙枣的种植，以探索改善生态环境的途径。努力做到边发展经济，边改善环境，达到经济效益、社会效益和环境效益三统一。     

Niche separation in two species of hare. Metabolic costs of plant phenolics

Summary The distributions of mountain hare (Lepus timidus) and European hare (L. europaeus) overlap in central Sweden, but they occupy separate food niches in winter. In Scandinavia, the European hare is mainly a grazer while mountain hare is a predominant browser. Browse contain high amounts of secondary metabolites, such as phenols, compared to grass. This raises the question if the two hare species differ in their metabolic tolerance of plant phenols and that these differences influence their food choice.Phenolic excretion in urine increased significantly with phenolic intake in both species. Excretion of glucuronic acid conjugates, one of the major pathways of elimination of phenols in both hare species, is positively correlated to phenolic intake and excretion. However, the extent of excretion of phenolics by this route was different in the two species of hare. European hares excreted substantially more glucuronic acid per amount of phenolics than mountain hare. The phenols were metabolized to a larger extent in the mountain hare, indicating a higher detoxification capacity. From these results it is likely that European hare have a higher cost for the detoxification of plant phenols compared to mountain hare. This cost and negative effect on sodium balance when feeding on browse may prevent exploitation of forest habitats by European hares, whereas mountain hare are better able to do so.     

Population differences in susceptibility to stress in Littorina saxatilis from metal contaminated and uncontaminated sites in the Isle of Man

Introduction Pollution-induced stress indices at various levels of organization, from sub-cellular to organism al level, have been investigated as a m eans of identifying and m onitoring environm ental contam ination. Since changes elicited by toxic m aterials m ust occur at the biochem ical, cellular and tissue levels of organization before effects w ould be observed at the organism al level, such m easures have been suggested as potential short-term , functional indices w hich can be used to…     

直升机尾部结构疲劳及缺陷容限试验装置研制及应用

目的 获得尾部结构的疲劳寿命和检查周期,满足民用直升机适航验证要求,保证飞机的飞行安全,开展复合材料尾部结构疲劳及缺陷容限试验技术研究。方法 介绍了尾部结构疲劳及缺陷容限试验专用试验台、气动冲击设备、柔性自动特征扫描成像无损检测系统等的设计及研制,采用研制的成套试验装置,实现尾部结构试验件连接约束和载荷边界的全面真实模拟、复杂载荷谱的精确控制、冲击损伤缺陷预制及缺陷自动识别与检测。结果 经试验验证,载荷误差小于2%,冲击能量误差小于2%,缺陷检测误差小于1 mm,各项指标都满足项目研究目标和技术指标要求。结论 研究成果在民用直升机研制中得到了成功应用,可为后续其他直升机尾部结构疲劳及缺陷容限疲劳试验提供良好的借鉴,具有重要的工程应用价值。     

植物铝胁迫发生机制及其内在缓解途径研究进展

本文总结了土壤中铝的存在形式及其化学行为,分析了以针叶人工林为例的诱发植物铝胁迫效应的内外部机制,以及铝胁迫在不同生态水平上对植物生长的影响。比较了环境铝胁迫下,植物体自身缓解环境铝威胁的不同途径。     

近地层氮氧化物和臭氧的区域分布研究

介绍了近地层氮氧化物和臭氧的区域分布研究方法,使用简化的区域尺度大气污染物传输模型和光化学反应模型,模拟计算了1990年中国主要城市排放氮氧化物的情景下,夏季(7月)主要城市的氮氧化物和相应的臭氧在近地层的浓度分布。      

铬离子对SBR工艺活性污泥毒性作用研究

针对重金属铬离子对SBR工艺系统中活性污泥的毒性作用,通过检测不同初始污泥容积指数(SVI)下SBR工艺活性污泥在不同铬负荷下的COD值、挥发性污泥浓度以及受铬离子影响的污泥容积指数(SVI),研究重金属铬离子对活性污泥的毒性作用以及对SBR工艺系统处理污水的影响。研究表明,重金属铬离子会导致SBR工艺系统出水COD升高;将铬离子对活性污泥的毒性作用按照挥发性污泥(MLVSS)铬负荷可划分为耐受范围、非耐受范围、细胞失活范围以及细胞分解范围。耐受范围铬负荷低于约30 mg Cr3+/gMLVSS,此范围内铬离子对于活性污泥的毒性作用不大,不致于导致系统出水水质变差;非耐受范围铬负荷在约30~65 mg Cr3+/g MLVSS,在铬离子作用下系统出水COD值明显高于对照系统;细胞失活范围铬负荷在约70~100 mg Cr3+/gMLVSS范围内,SVI大幅下降,微生物部份死亡和失活,出水COD尽管有一些下降,但与进水COD相比差不了多少;细胞分解范围铬负荷在约100 mg Cr3+/gMLVSS以上,微生物大量死亡,部分死亡细胞分解,系统出水COD值因微生物的死亡分解而超出进水COD值,受铬离子影响的系统SVI值大幅度降低。     

不适宜生长条件对混菌降解苯胺的影响

分别从台州和衢州某化工厂的好氧池中分离筛选得到2株苯胺降解菌TZ1和JH1,经16S rDNA测序鉴定为Comamonas sp.TZ1和Pseudomonas sp.JH1,均具有较强的苯胺降解能力,培养24 h后,可使初始浓度为800 mg/L的苯胺去除率达到96.4%~98.4%。在此基础上,按体积比1∶1将2株菌液进行混合构建了混合菌体系,进而对比考察了苯胺初始浓度、pH、盐度和重金属等环境因子对单一菌和混合菌生长量及降解苯胺效果的影响,重点探讨混合菌对不适宜生长环境的适应性及其对苯胺的降解特性。通过单一菌和混合菌对比实验发现,在适宜苯胺初始浓度、pH和盐度条件下,混合菌的生长量略高于单一菌;在不适宜生长的高浓度苯胺、pH和盐度条件下,混合菌也表现出了更强的适应性和苯胺矿化能力。Zn2+和Cr6+耐受实验则表明,对于Cr6+,混合菌表现出了更强的耐受能力,而对于Zn2+并没有表现出更强的耐受能力。     

Ozone and/or Water Stresses Could have Influenced the Betula ermanii Cham. Forest Decline Observed at Oku-Nikko, Japan

A serious forest decline of Betula ermanii Cham. has been observed at Mt. Mae-Shirane, Oku-Nikko, Japan, where high ozone (O₃) concentration and severe water deficiency have been measured. In order to consider the possibility whether O₃ and/or water stresses could have been the causes of the forest decline of B. ermanii, plant growth experiments were conducted in environment-controlled growth cabinets. Two-year-old seedlings of B. ermanii were exposed to either charcoal-filtered air (O₃ concentration <5 ppb) or 50 ppb O₃ (daily average, ranging between 20–100 ppb) for 123 days at 20.0/12.5 ± 1.0°C (day/night) and 70/80 ± 7% relative humidity (day/night). Simultaneously, seedlings were treated with three watering regime: 1.0 < pF < 1.8 (no water stress), 1.8 < pF < 2.5 (mild water stress) or 2.5 < pF < 3.0 (severe water stress). O₃ exposure significantly reduced the dry weights of leaf, root and the whole plant, while water stress significantly reduced the dry weights of each organ and the whole plant. Significant reductions of net photosynthesis, transpiration and stomatal conductance were also observed under O₃ and/or water deficiency treatments, while contents of RuBP carboxylase/oxygenase (Rubisco), chlorophyll _a+b and some essential nutrient elements (N, P, K, Mg and Ca) were not markedly changed. It was suggested that the decrease in net photosynthetic rate induced mainly by stomatal closure was the major cause of the growth reduction under O₃ and/or water stresses. No significant interactions between O₃ and water stresses were observed in terms of the depression of dry matter production, which suggested that simultaneous stress treatments of O₃ exposure and water deficiency could affect the tree growth of B. ermanii additively.