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61.
Plants can respond physiologically to damaging ultraviolet-B radiation by altering leaf chemistry, especially UV absorbing phenolic compounds. However, the effects on terpene emissions have received little attention. We conducted two field trials in plots with supplemented UV-B radiation and assessed the influence of feeding by pine weevils, Hylobius abietis L., on volatile emissions from 3-year old Norway spruce trees (Picea abies L. Karst.). We collected emissions from branch tips distal to the feeding weevils, and from whole branches including the damage sites. Weevil feeding clearly induced the emission of monoterpenes and sesquiterpenes, particularly linalool and (E)-β-farnesene, from branch tips, and the sums of monoterpenes and sesquiterpenes emitted by whole branches were substantially increased. We discovered little effect of UV-B radiation up to 30% above the ambient level on volatile emissions from branch tips distal to damage sites, but there was a possible effect on bark emissions from damage sites.  相似文献   
62.
Massive blooms of the harmful benthic dinoflagellate Ostreopsis cf. ovata are of growing environmental concern in the Mediterranean, having recently caused adverse effects on benthic invertebrates and also some intoxication episodes to humans.The toxicological potential of produced palytoxin-like compounds was investigated in the present study on a typical marine sentinel species, the mussel Mytilus galloprovincialis. Organisms were sampled during various phases of a O. cf. ovata bloom, in two differently impacted sites. The presence of the algal toxins was indirectly assessed in mussels tissues (mouse test and hemolysis neutralization assay), while biological and toxicological effects were evaluated through the measurement of osmoregulatory and neurotoxic alterations (Na+/K+-ATPase and acetylcholinesterase activities), oxidative stress responses (antioxidant defences and total oxyradical scavenging capacity), lipid peroxidation processes (level of malondialdehyde), peroxisomal proliferation, organelle dysfunctions (lysosomal membrane stability, accumulation of lipofuscin and neutral lipids), immunological impairment (granulocytes percentage).Obtained results demonstrated a significant accumulation of algal toxins in mussels exposed to O. cf. ovata. These organisms exhibited a marked inhibition of the Na+/K+-ATPase activity and alterations of immunological, lysosomal and neurotoxic responses. Markers of oxidative stress showed more limited variations suggesting that toxicity of the O. cf. ovata toxins is not primarily mediated by an over production of reactive oxygen species. This study provided preliminary results on the usefulness of a multi-biomarker approach to assess biological alterations and toxicological events associated to blooms of O. cf. ovata in marine organisms.  相似文献   
63.
Extensive use of pharmaceuticals in human and veterinary medicine and aquaculture practices pose a serious threat to aquatic organisms. In the present investigation, Cirrhinus mrigala an Indian major carp was exposed to different concentrations of clofibric acid (CA) and diclofenac (DCF) and certain biochemical and ionoregulatory responses were assessed under short and long term exposures. During short-term (96 h) exposure period, plasma glucose and sodium (Na+) levels were increased at all concentrations (1, 10 and 100 μg L−1) of CA and DCF treated fish. Plasma protein and chloride (Cl) levels were found to be decreased at all concentrations of CA and DCF exposed fish comparatively to control groups. Meanwhile an increase in plasma potassium (K+) level was noted in fish exposed to CA treatments alone and in DCF treatments it was decreased. In long-term exposure (35 d), plasma Na+ and Cl levels were found to be significantly increased at all concentration of CA and DCF. However, a biphasic trend was observed in plasma glucose, protein and K+ levels. In both the treatments, a significant (P < 0.01 and P < 0.05) changes were observed in all parameters measured in fish exposed to different concentrations of CA and DCF. The results of the present investigation indicate that both the drugs caused significant changes in biochemical and ionoregulatory responses of fish at all concentrations. The alterations of these parameters can be useful in monitoring of pharmaceutical residues present in aquatic environment.  相似文献   
64.
根据“十二五”环境保护规划要求,现役火电机组大部分脱硫装置必须拆除旁路挡板。介绍了现役火电机组脱硫装置旁路烟道设置所发挥的作用,分析了现役火电机组脱硫装置拆除旁路挡板后对机组所产生的影响及存在问题,并提出了相应的改造、完善和运维管理措施,为现役火电机组拆除脱硫旁路挡板后的工作提供借鉴和帮助。  相似文献   
65.
黄河三角洲土地利用/土地覆盖变化研究现状与展望   总被引:12,自引:2,他引:12  
土地利用/土地覆盖变化是全球环境变化研究的3个核心主题之一。黄河三角洲是我国乃至世界造陆速度最快的河口三角洲之一。伴随着人口的不断增加,黄河流域经济的发展,河口地带油气的开发,黄河三角洲土地利用/土地覆盖发生了迅速的变化,从而引发了土壤盐渍化、水污染严重、湿地资源保护受到威胁等一系列生态环境问题。论文以黄河三角洲为典型样区,把其土地利用/土地覆盖变化的研究作为全球环境变化研究的一个缩影,为全球性土地利用/土地覆盖变化模型的建立提供依据。论文首先介绍了黄河三角洲概况,其次对该地区土地利用/土地覆盖变化探测方法、结果进行了对比、归纳,接着回顾了该地区对土地利用/土地覆盖变化的驱动力分析以及模型预测,然后介绍了土地利用/土地覆盖与环境变化交互作用等的研究状况,最后总结了目前黄河三角洲土地利用/土地覆盖研究所取得的成绩和存在的不足,同时为进一步开展该地区的研究工作提出了若干建议。  相似文献   
66.
探讨了黑麦草对水体中镉-壬基酚(Cd-NP)复合污染的生理响应及修复作用.结果表明,单一Cd污染情况下,高浓度Cd~(2+)(10 mg·L~(-1))对黑麦草的生物量和叶绿素含量均有显著的抑制作用,植株过氧化物酶(POD)和多酚氧化酶(PPO)活性显著增大.单一NP污染情况下,黑麦草的生物量、叶绿素含量和MDA含量均无显著性变化;高浓度NP(5 mg·L~(-1))存在下,植株POD活性显著增大.当黑麦草受到复合污染胁迫时,高浓度NP的加入降低了Cd的抑制作用,使黑麦草的MDA含量有所回落,植株PPO活性有所下降.Cd~(2+)浓度为1 mg·L~(-1)时,黑麦草对Cd~(2+)有较好的去除效果,12 h的去除率达到了55.3%.吸收时间超过12 h,高浓度NP对黑麦草吸收Cd~(2+)有较显著的促进作用.NP浓度对植株地下部分Cd~(2+)吸收量有极显著影响,转移系数随着NP浓度增大而呈现上升趋势.NP浓度为5 mg·L~(-1)时,黑麦草对NP的吸收效果较好,24 h的吸收率为44.6%.低浓度Cd~(2+)的加入对黑麦草去除NP无显著性影响,而高浓度Cd~(2+)的加入对黑麦草吸收和降解NP均有极为显著的抑制作用.  相似文献   
67.
A tree-ring width chronology developed from Pinus tabulaeformis tree-rings of Hasi Mountain was employed to analyze responses of tree-ring to different climatic metrics. Correlation analyses between tree-ring chronology and precipitation and temperature suggest that tree growth is both limited by precipitation and temperature, and moisture is the principal limiting factor of tree-ring width. To find a suitable moisture index to be reconstructed, three moisture indices considering precipitation and evaporation even water balance are chosen to be analyzed. The results suggest that the PDSI is an appropriate index as predictor of tree-ring width and can be used to reconstruct in this area.  相似文献   
68.
Pb2+、Cd2+、Zn2+在低浓度作用下,随处理浓度的升高,刺激蚕豆(Vicia faba)DNA含量(处理浓度分别低于10.0、0.50、50.0ppm)和RNA含量(处理浓度分别低于10.0、50.0、50.0ppm),DNase活性(处理浓度均低于10.0ppm)和RNase活性(处理浓度分别低于20.0、10.0、50.0ppm)相应地升高;当处理浓度超过相应浓度时,DNA和RNA含量以及DNase与RNase活性随浓度升高而降低。Hg2+在小于0.05ppm时使RNase活性升高,高于该浓度使其降低,其它各指标无上述规律性变化。重金属对核酸代谢的影响结果取决于植物组织的适应性反应与金属离子的毒性反应的强度。文章还讨论了金属离子特征和可能存在的不同代谢活动的抗性诱导体系对植物毒性的影响,以及蛋白质的代谢活动对植物适应性水平的影响。  相似文献   
69.
森林对氮饱和的响应   总被引:5,自引:0,他引:5  
氮素缺乏是大多数北半球森林生态系统普遍存在的现象,是森林生长的主要限制因子之一.但是化石燃料和氮肥施用使得大量的氮化合物进入大气,多余的氮输入引起森林衰退和土壤酸化,出现了“氮饱和”现象.本文就氮饱和的定义、研究手段及监测指标、森林对其的生理和群落响应等进行初步分析,并提出建议和展望,以期能为森林对氮饱和的响应的进一步研究提供科学依据.表1参46  相似文献   
70.
东平湖是南水北调东线工程输水线路下游的最后一个调蓄湖泊.为探究调水后的东平湖浮游动物时空响应,于2016—2017年对东平湖浮游动物进行了涵盖春(4月)、夏(7月)、秋(10月)、冬(1月)的4次调查,共检出浮游动物3类72种(属),其中,轮虫51种(70.83%)、枝角类11种(15.28%)、桡足类10种(13.8...  相似文献   
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