首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
运用电生理学方法,观察Hg(2+)、Zn(2+)联合对克氏螯虾第一触角内侧枝神经动作电位放电的影响.当Hg(2+)、Zn(2+)浓度分别达到0.000025mg/L和0.05mg/L时,这两种离子联合对触角神经的毒性作用潜伏期(TL)为46.75±22.69min(N=8),触角神经动作电位放电持续时间(DD)为115.28±40.95min,表示其放电频率(Fn/Fl)与作用时间关系的直线回归方程的b值为-0.0818,与渔业水体最高允许Zn(2+)含量0.1mg/L比较,两者间无显著差异(P>0.1).说明Hg2+对Zn(2+)的毒性具有增强效应.因此,在对有Hg(2+)和Zn(2+)污染的水体进行评估时,似应考虑到Hg(2+)对Zn(2+)毒性的增强效应.  相似文献   

2.
Cd^2+对玉米种子活力的影响及Ca^2+的拮抗作用   总被引:8,自引:0,他引:8  
用不同浓度(c)的Cd2+和Cd2++Ca2+处理玉米种子,以研究Cd2+对玉米种子活力的毒害及Ca2+对Cd2+的拮抗作用,结果表明:在0~0.5mmol/L的c(Cd2+)范围内,种子的发芽率、幼苗生长量随c(Cd2+)的增大而降低,Cd2+能降低玉米幼苗中超氧物歧化酶(SOD)和过氧化氢酶(CAT)的活性,并能增加膜脂过氧化产物丙二醛(MDA)的含量.用Cd2++Ca2+处理玉米种子时,Ca2+能减少以至消除Ca2+对种子活力和幼苗生长的毒害作用,其中c(Cd2+)为10mmol/L的拮抗作用明显大于5mmol/L.  相似文献   

3.
九龙江口桐花树红树林对重金属的吸收与累积   总被引:18,自引:0,他引:18  
探讨了福建九龙江口桐花树红树林对CU、Ph、Zn、Cd、Mn元素的吸收、累积及分布.结果表明:该林地土壤5种元素的储量关系为Mn>Zn>Ph>CU≥Cd;植物体不同部位,各元素含量有着明显的差异,含量范围分别为Ch1.51~5.70、Pb1.30~10.70、Zn18.0~100.1、Cd0.04~0.23和Mn15.5~237.5(w/10-6);植物对土壤元素的富集系数大小依次为Cd>Zn>Mn>Cu>Ph;群落现存生物量中,CU、Pb、Zn、Cd、Mn元素的现存累积量分别为16.56、63.30、445.05、1.14和1656.93(ρA/mg·m-2).其中,地下部分别占70.2%、81.8%、76.2%、72.2%和82.1%;林地残留物相应元素的储量分别为211.11、184.00、1941.69、6.19和22248.31(ρA/μg·m-2).  相似文献   

4.
测定了由光合细菌 P9479 株与酵母 Y9407 株经原生质融合构建的跨界融合子 Foaz 及其亲株在净化豆制品废水反应中0 、0 .1 、5 .0 、10 .0 、100 .0 mg/ L Fe3 + 质量浓度和0 、150 、300 、400 、800 mg/ L Mg2 + 质量浓度下的β-类胡萝卜素色素含量及 B O D5 去除效率.结果表明, Fe3 + 对融合子 Foaz 及光合细菌中β- 类胡萝卜素的合成有明显的促进作用,当ρ( Fe3 + ) 为5 .0 mg/ L 时,融合子 Foaz 及光合细菌中β- 类胡萝卜素的质量分数w 达到最高水平,分别为4 .9 mg/g 和2 .4 mg/g .而 Mg2 + 对融合子及其亲株中β- 类胡萝卜素的合成有一定抑制作用  相似文献   

5.
试验了Ni、Zn、Mn、Sn、Cr和Cu等6种重金属及油处理剂对水稻根系的影响,结果表明.水中含Ni0.007mg/1、Cu0.005mg/1时,能阻碍根系的伸长;含Zn0.5mg/1以上时。不利于根系的伸长;水中含Mn20mg/1,Sn、Cr ̄(6-)各5mg/1时,对根系有明显危害;水中含Cr ̄(2+)+Cr ̄(6+)时,当1种离子浓度保持不变,根系的抑制程度随着另1种离子浓度的增加而增大。水中含油处理剂1000mg/1时,能抑制水稻发根。  相似文献   

6.
ZrO2负载过渡金属氧化物催化剂对CO+NO(O2)反应的影响   总被引:6,自引:0,他引:6  
王月娟  周仁贤 《环境化学》1999,18(5):432-436
本文运用固定床微反技术考察了Cu,Fe,Mn,Cr,Co和Ni负载(ZrO2载体)氧化物对CO+NO(O2)反应的催化活性。研究了NO和CO在不同比例时,催化剂对N2O和N2生成的影响。结果表明,在NO+CO反应中,NO和CO的比例对催化剂活性和N2O,N2生成均有明显的影响,CuOx/ZrO2催化剂的活性最高;N2O是NO+CO反应的中间产物,低温或NO过量时有利于生成N2O,高温或NO不足时有  相似文献   

7.
硅营养缓解水稻幼苗Cd、Cr毒害的生理研究   总被引:58,自引:0,他引:58  
两系法杂交稻“培杂山青”和常规稻“双桂36”幼苗经较高浓度的Cd2+(c=9.6~38.4μmol/L)或Cr3+(c=7.5~25.0μmol/L)处理可使其叶片光合速率、叶绿素(a+b)含量、叶绿素a/b比值、叶片可溶性糖、淀粉及可溶性蛋白质含量降低,而叶片的POD活性提高;低浓度Cd2+(c=4.8μmol/L)和Cr3+(c=2.5μmol/L)处理幼苗对上述生理指标有提高作用,但POD活性稍降低.加Si(Na2SiO3)[c(SiO2)=1.331mmol/L]的Cd、Cr处理比不加Si的Cd、Cr处理的幼苗叶片上述生理指标明显提高,且明显降低其POD活性.说明Si在不同程度上起到缓解Cd、Cr对水稻幼苗的毒害作用.而c(Cr3+)=25.0μmol/L是“双桂36”幼苗的致死浓度  相似文献   

8.
水稻盆栽试验结果表明,施用CaO2、MgO2和BaO2三种过氧化物(释氧物)能在一定时间范围内提高土壤Eh值.在土壤中添加Fe(2+)和葡萄糖来模拟潜育性土壤的强还原条件,施用过氧化物能明显降低土壤还原物质总量和活性还原物质含量,减轻Fe(2+)等还原物质对水稻的毒害,促进水稻的正常生长发育,提高产量。  相似文献   

9.
啤酒酵母吸附Cu^2+的模拟实验   总被引:17,自引:0,他引:17  
研究了啤酒酵母吸附重金属Cu2+离子的可行性及反应条件对去除作用的影响.结果表明:用啤酒酵母处理Cu2+,在起始浓度ρ0为20~400mg/L的范围内,吸附量w为2.98~12.03mg/g,说明用啤酒酵母去除重金属Cu2+是可行的.吸附反应在10~20min基本达到吸附平衡.最适反应温度(θ)和pH分别为15~20℃和4.0~6.0,酵母细胞有一最适投加用量.Freundlich吸附等温方程的分析表明,η与重金属离子种类有关,与酵母细胞种类关系较小;k值与酵母种类和重金属离子种类有关.  相似文献   

10.
成熟蕃茄匀浆后,经硫酸铵盐析,DEAE-SephadexA-50离子交换层析,SepadexG-100凝胶过滤和Melibiose-Agarose亲和层析,获得了α-D-半乳糖苷酶(C.E.3.2.1.11)。酶制剂经PAGE检测为一条带;SDS-G-PAGE测得酶Mr为34000;比活力52.9U/mg·;提纯倍数为52901产率为45%.酶专-催化以α-D-半乳糖为末端a-(1,3)连接的糖苷键,以PNPG(对硝基苯-α-D-半乳糖昔)为废物,酶催化反应的Km=0.11mmol/L,Vmax为67μmol·mg1-·min-1.t稳定范是0~35℃;PH稳定范围是4.0~7.0.最适pH为5.1.半乳糖是酶的竞争性抑制剂;Cu2+、Zn2+、Mn2+、Fe3+、Ag+和EDTA对酶活性无影响.纯酶制剂可作为B型血向O型血转化的工具酶液.  相似文献   

11.
基因污染与生态环境安全   总被引:6,自引:0,他引:6  
论述了基因污染可能对生态环境安全造成的影响。转基因作物有可能污染天然物种的基因库;有可能破坏传统农作物品种的遗传多样性,加速作物种植品种的单一化及基因资源的流失;使抗除草剂作物的基因向野生或半野生植物漂移的可能性加大,有可能创造出“超级杂草”;带有病毒型转基因作物的基因重组,有可能创造出新的植物病毒,导致新的病害;BT转基因抗虫作物分泌的毒素,在食物链中传递,很难加以控制,对非目标生物造成危害,并最终破坏自然生态系统的平衡。文章还从不同角度分析了基因污染的严重性。  相似文献   

12.
土肥的基础地位是不随社会性质或社会经济类型的变化而变化的,它既具重要性,又具长久性.市场经济是仍然需要土肥科技的.土肥科技的教学、科研和推广的力度必须加大,局面必须改观,且宜快不宜迟.土肥科技工作者一定要将培肥地力作为中心工作.根据广东的实际,增施有机肥是培肥地力的主要措施,因而抓秸秆还田和发展冬绿肥是我们工作的重点.  相似文献   

13.
Indoor and outdoor air pollution is known to contribute to increased lung cancer incidence. This study is the first to address the contribution of home heating fuel and geographical course particulate matter (PM10) concentrations to lung cancer rates in New Hampshire, USA. First, Pearson correlation analysis and geographically weighted regression were used to investigate spatial relationships between outdoor PM10 and lung cancer rates. While the aforementioned analyses did not indicate a significant contribution of PM10 to lung cancer in the state, there was a trend towards a significant association in the northern and southwestern regions of the state. Second, case-control data were used to estimate the contributions of indoor pollution and secondhand smoke to the risk of lung cancer with adjustment for confounders. Increased risk was found among those who used wood or coal to heat their homes for more than 10 winters before the age of 18, with a significant increase in risk per winter. Resulting data suggest that further investigation of the relationship between heating-related air pollution levels and lung cancer risk is needed.  相似文献   

14.
High concentrations of metals (cadmium, copper, lead, and zinc) and of lindane were measured in the sediment and in the spawn and tadpoles of Bufo bufo, Rana dalmatina, and Rana ridibunda from two Austrian locations. Residues in spawn suggest maternal transfer. Increase of the metal concentrations from spawn to advanced tadpole stage is explained by the larval microphaguous feeding habits which cause high exposition of the tadpoles to substances concentrating in sediments and suspended particles. Metal and pesticide concentrations in spawn and tadpoles are toxic to various other aquatic organisms and are furthermore considered to be potentially hazardous to the anurans themselves. The results are conform with world‐wide observations of contamination of anuran larvae with heavy metals, and prove the significance of non‐point source chemical exposure due to allochthonous toxicant input by wind load and precipitation.  相似文献   

15.
湿解产物与堆肥在土壤中的稳定性和腐熟度比较分析   总被引:1,自引:1,他引:1  
研究了不同培养阶段湿解产物与土壤混合物(HTS)的物质变化特征、稳定性和腐熟度,并与堆肥和土壤混合物(CS)及自然土壤进行了对比。结果表明:在培养过程中,所有HTS和CS的参数变化趋势相似,HTS的温度变化接近于CS的温度变化,稍高于自然土壤的温度,低于环境温度;pH值变化不大,基本稳定在7.6左右;在培养初期,水溶性有机碳比有机态氮w(WSC)/w(Norg)小于0.55,种子发芽系数(GI)高于80%;培养14d后,w(C)/w(N)降低至小于20,w(NH4 -N)/w(NO3--N)渐渐趋于稳定至小于0.16,GI基本高于100%;49d后,HTS的CO2释放率接近CS和自然土壤的CO2释放率;种子发芽系数的变化表明,湿解产物中含有更丰富的营养元素,可以促进植物根系的生长;相关性分析显示,w(WSC)/w(Norg)、w(NH4 -N)/w(NO3--N)和GI可以作为湿解产物腐熟度的评价指标。综合各项参数表明,湿解产物在土壤中会很快达到稳定,可以安全应用。  相似文献   

16.
河流底泥污染及其控制与修复   总被引:3,自引:0,他引:3  
水体底泥污染是世界范围内的一个环境问题。污染物通过大气沉降、废水排放、雨水淋溶与冲刷进入水体,最后沉积到底泥中并逐渐富集,使底泥受到严重污染。在河流环境中,河床沉积底泥以推移和悬浮形式输送,很大程度上导致了上覆水和沉积底泥的相互物理作用。河流有强有力的自然环境,在河流系统中趋向有利于沉积底泥的解吸作用,从而将会影响上覆水的水质。因此,在水质管理计划中,应该将已污染的沉积底泥作为一个污染源予以考虑,沉积底泥是河流污染的一个重要方面。文章根据近年来国内外对河流底泥污染的控制、处理、修复及利用的文献资料,分析了河流底泥的污染现状及主要类型,包括重金属、NP营养物质、难降解有机物和持久性有毒污染物等,指出了目前在底泥污染修复中存在的问题。针对河流底泥污染控制与修复技术,介绍了除控制外源污染物外的物理修复、化学修复和生物修复等几种主要的修复方法和技术,分析了各种方法的利弊以及适用情况。在阐述了堆肥、建材利用、低温热解、湿地及栖息地建设、修复废弃地和建设填方等利用方式后,提出具体的控制和修复应因地制宜,综合各种恢复技术及利用方式,以达到控制及修复污染的河流底泥,恢复河流生态系统之目的。  相似文献   

17.
● Adsorption of PFASs on MPs and its mechanisms are critically reviewed. ● MPs could alter the transport and transformation of PFASs in aquatic environments. ● Combined toxicity of MPs and PFASs at organismal and molecular levels is discussed. Microplastics (MPs) are recognized as vectors for the transport of organic contaminants in aquatic environments in addition to their own adverse effects on aquatic organisms. Per- and polyfluoroalkyl substances (PFASs) are widely present in aquatic environments due to their widespread applications, and thus coexist with MPs. Therefore, we focus on the interaction of MPs and PFASs and related combined toxicity in aquatic environments in this work. The adsorption of PFASs on MPs is critically reviewed, and new mechanisms such as halogen bonding, π-π interaction, cation-π interactions, and micelle formation are proposed. Moreover, the effect of MPs on the transport and transformation of PFASs in aquatic environments is discussed. Based on four typical aquatic organisms (shellfish, Daphnia, algae, and fish), the toxicity of MPs and/or PFASs at the organismal or molecular levels is also evaluated and summarized. Finally, challenges and research perspectives are proposed, and the roles of the shapes and aging process of MPs on PFAS biogeochemical processes and toxicity, especially on PFAS substitutes, are recommended for further investigation. This review provides a better understanding of the interactions and toxic effects of coexisting MPs and PFASs in aquatic environments.  相似文献   

18.
Recent extinctions often resulted from humans retaliating against wildlife that threatened people's interests or were perceived to threaten current or future interests. Today's subfield of human-wildlife conflict and coexistence (HWCC) grew out of an original anthropocentric concern with such real or perceived threats and then, starting in the mid-1990s, with protecting valued species from people. Recent work in ethics and law has shifted priorities toward coexistence between people and wild animals. To spur scientific progress and more effective practice, we examined 4 widespread assumptions about HWCC that need to be tested rigorously: scientists are neutral and objective about HWCC; current participatory, consensus-based decisions provide just and fair means to overcome challenges in HWCC; wildlife threats to human interests are getting worse; and wildlife damage to human interests is additive to other sources of damage. The first 2 assumptions are clearly testable, but if they are entangled can become a wicked problem and may need debunking as myths if they cannot be disentangled. Some assumptions have seldom or never been tested and those that have been tested appear dubious, yet the use of the assumptions continues in the practice and scholarship of HWCC. We call for tests of assumptions and debunking of myths in the scholarship of HWCC. Adherence to the principles of scientific integrity and application of standards of evidence can help advance our call. We also call for practitioners and interest groups to improve the constitutive process prior to decision making about wildlife. We predict these steps will hasten scientific progress toward evidence-based interventions and improve the fairness, ethics, and legality of coexistence strategies.  相似文献   

19.
水循环经济与水资源合理开发利用研究   总被引:6,自引:1,他引:6  
马忠玉  蒋洪强 《生态环境》2006,15(2):416-423
在分析水循环经济的概念和基本特征、回顾国内外水循环经济与水资源合理开发利用历史演进和研究进程的基础上,陈述了可持续发展理论、物质代谢理论和产业生态学理论是水循环经济研究的三大新理论支柱。从现代水资源合理开发利用研究必须从系统定量的角度研究水资源系统与水社会经济系统的整体行为、演化规律及其相互作用的角度,指出了物质流分析技术(MFA)与投入产出分析技术(I/O)是水循环经济研究的主流方法。分别阐明了水循环经济理论体系构建的研究、水循环经济技术创新问题的研究、水循环经济发展模式选择问题的研究、水循环经济管理体制及经济机制问题的研究是当前水循环经济研究的四项重点内容。  相似文献   

20.
Two different methods to predict biotic integrity were tested and compared in the present paper. The first one tries to predict the fish indices of biotic integrity (IBI) at the state or regional scale based on the most similar observations to a specific target site of interest using the simple to implement k-nearest neighbors (or kNN) method. Two different distance functions were considered to find the k-nearest neighbors: the Euclidean and the Mahalanobis. The second method was applied on the same datasets and consisted of a step-wise multiple regression. The two modeling approaches yielded similar results but kNN proved to be more time-efficient and very fast computationally for the given dataset sizes, which allowed applying a leave-one-out cross validation.In an attempt to reveal the importance of scale in the prediction of IBI, regression models were constructed at the state (or regional) scale and at the more refined cluster of sampling sites scale. Clusters of sites were extracted using Kohonen's self-organizing maps (SOM) followed by k-means clustering of the SOM neurons. Cluster-level regression models, constructed after site patterning, performed better in IBI prediction than global regression models constructed without any previous site patterning. The importance of identifying groups of sites with similar environmental characteristics affecting the IBI was revealed. The combined use of site patterning and regression modeling for IBI prediction also helped identifying important variables acting at the local scale which remain latent at the global scale.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号