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 62 毫秒
1.
荇菜对镉污水的净化作用及其机制探讨   总被引:6,自引:0,他引:6  
将水生植物荇菜在含不同浓度CdCl2的培养液中培养不同的时间,分析测定荇菜的茎叶、根系、培养液中的含镉量,植株细胞中超氧阴离子(O^-2)、丙二醛(MDA)的含量、超氧化物歧化酶(SOD)活性及细胞外渗的量。实验结果表明:荇菜对镉有较强的耐受性,5mg/L镉为春最小致死浓度,荇菜通过根系的吸收和分泌物的吸附作用固定溶液中的镉,对含镉污水有较高的净化能力,最高可清除污水中99.5%的镉,在可耐受的范  相似文献   

2.
固定化甲烷八叠球菌提高甲烷化作用研究   总被引:4,自引:0,他引:4  
用聚乙烯醇( P V A) 为包埋剂对甲烷八叠球菌( Methanosarcina ) 的富集培养物进行固定化, 并以甲醇为唯一碳源对其产气特性进行了研究.结果表明:以甲醇为唯一碳源时,固定化甲烷八叠球菌与非固定化甲烷八叠球菌的总产气量相似,但两者的产气特性有明显不同.固定化甲烷八叠球菌产气迟于非固定化甲烷八叠球菌,固定化甲烷八叠球菌的产气集中,在产气高峰两天中的产气量占总产气量的66 .0 % .非固定化甲烷八叠球菌产气平稳, 平均日产甲烷量为8 .91 m L/d.固定化甲烷八叠球的电子显微镜观察结果表明, 细胞在固定介质中多呈较大包囊存在,包囊直径30 ~50 μm .固定化甲烷八叠球处理豆制品废水的结果表明,在低有机物负荷下,固定化甲烷八叠球菌发挥着很大作用,有较低的出水 C O D 和较高的甲烷含量.在较高有机物负荷下,与对照无明显差别.其原因是在高有机物负荷和短水滞留期运转条件下,固定化甲烷八叠球菌受到抑制而失去活性所致  相似文献   

3.
报道了锦蛇属团花锦蛇(E.davidi)、绿锦蛇(E.prvsina)和三索锦蛇(E.radiata)3个种的核型和Ag-NORs,团花锦蛇的型2n=36(8V+6sV+2I+20M),绿锦蛇的核型2n=36(7V+7sV+2I+20m),三索锦蛇的核型2n=40(6V+3sV+2sI+5I+24m);①团花锦蛇和绿锦蛇的染色体数目和结构与此属大多数咱的相似,;②此种为雄性,未见染色体异型。③Ag  相似文献   

4.
对Al2(SO4)3,Ca(OH)2不同反应条件下去除洗涤废水中总磷的情况作了对比试验,结果表明,按Ca(OH)2:TP=3.7:1.0(重量比)投加试剂,回用生成的磷灰石沉淀助凝,TP(总磷)去除率可达95%,CODcr有少量去除。  相似文献   

5.
不同消毒剂对水中脊髓灰质炎病毒灭活的比较   总被引:4,自引:1,他引:3  
将脊髓灰质炎病毒( Polio V) 及不同消毒剂投加到模拟水样中,按不同接触时间1 ,3 ,10 ,30 min 取样,空斑定量. 当模拟水有机质含量 C O D 为20 mg/ L,病毒浓度n( P F U) ≈1 ×105 m L- 1 时,分别投加氯制剂有效氯ρ( Cl)16 mg/ L,接触30 min ;ρ( Cl O2) = 8 .0 mg/ L,30 min ; Cl+ Cl O2 联合消毒剂(5 .0 + 5 .0) mg/ L,30 min ;ρ( O3) = 1 .22 mg/ L,10 min 时;可使病毒彻底灭活. 它们使 Polio V 达到99 .99 % 灭活的浓度时间乘积( ρ×t) 值分别是662 .5 ,129 .5 ,200 .0 和3 .2 mg L- 1 min . 消毒效果( 顺序) 为 O3 > Cl O2 > Cl+ Cl O2 > Cl. 联合消毒灭活 Polio V 的效果为 Cl 的3 .3 倍,表明将 Cl 与 Cl O2 联合应用具有协同效应,优于传统的单一加氯消毒方式  相似文献   

6.
蔓茎堇菜细胞悬浮培养的研究   总被引:5,自引:0,他引:5  
对蔓茎堇菜细胞悬浮培养的条件进行了选择,并测定悬浮培养的生长动态。结果表明:蔓茎堇菜细胞悬浮培养的最适接种量为2.0~3.5g(50mL);最适培养基为MS+2.0mg/L2,4-D+1.0mg/L ZT+300mg/L LH+200g/L蔗糖(或葡萄糖),pH5.8;细胞悬浮培养一个周期过程中细胞数目增长的动态基本上是一条S型曲线,对数生长期明显;细胞鲜重(mFW)和细胞干重(mDW)则与细胞  相似文献   

7.
系统评价EM菌液在生活污水处理中的应用效果   总被引:28,自引:0,他引:28  
采用在生活污水中投加有效微生物群的方法,系统评价了EM对污水中三类常见污染物去除率的影响。结果表明(1)好氧条件下,EM显著提高污水CODcr去除的适宜加入量为5/10000-1/1000,增幅达达10%;厌氧条件下,EM对污水CODcr的去除没有促进作用。(2)EM在好氧条件下能显著或极显著提高污水NH4^+-N的硝化程度,当EM加量为5/1000时效效果最好,增幅达37.62%,厌氧条件下,当  相似文献   

8.
固定化细胞生产L—苯丙氨酸研究   总被引:2,自引:0,他引:2  
用聚惭烯醇(PVA)凝胶包埋固定假单胞菌E4-106细胞,最佳ρ(PVA)为80g/L;最适湿细胞包埋量为每ml凝胶0.3g;转阔顺收率为78%,连续反应21批次后,固定化细胞酶活力为初始最高活和固定化细胞进行间歇式批次反应,结果表明其酶活性半寿期为4个月;制得的固定化细胞为直径约3mm的珠减颗粒,机械强度良好,间歇式批次反应10个月,固定化细胞凝胶颗粒无溃破。  相似文献   

9.
大玉竹低聚糖硫酸酯抗HSV-2病毒活性的研究   总被引:8,自引:0,他引:8  
从传统中药大玉竹中提取低聚糖Poos,用吡啶-氯磺酸法制备了它的硫酸酯衍生物S-Poos,产物经红外鉴定,证实Poos硫酸酯化后羟基连上硫酸基,硫含量为8.47%,取代度(Ds)为0.6体外实验研究了Poos、S-Poos对非洲绿猴肾细胞(Vero)的细胞毒怀和抗单纯疱疹病毒2型(HSV-2)活性。结果表明,Poos和S-Poos都无细胞毒性。Poos本身无抗病毒活性,对HSV-2引起的细胞病变和  相似文献   

10.
O(^1D)与CF2ClBr的反应研究   总被引:3,自引:0,他引:3  
于勇  潘循皙 《环境化学》1999,18(5):414-421
本文研究了CF2ClBr-O3体系在253.7nm紫外光照下所引发的O(^1D)与CF2ClBr的反应。O(^1D)与CF2ClBr反应的最终产物为CF2O,Cl2,B2r;实验中得到O(^1D)与CF2ClBr的反应速率常数为1.01×10^-10cm^3·molecule^-1·s^-1,并且对O(^3P)与CF2LlBr的反应可能性以及O(^1D)与CF2ClBr的反应机理进行了讨论。  相似文献   

11.
Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación  相似文献   

12.
Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.  相似文献   

13.
Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.  相似文献   

14.
Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.  相似文献   

15.
Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.  相似文献   

16.
Effects of Coffee Management on Deforestation Rates and Forest Integrity   总被引:1,自引:0,他引:1  
Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km2 around Bonga and 3000 km2 in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques  相似文献   

17.
As drivers of terrestrial ecosystems, humans have replaced large carnivores in most areas, and human influence not only exerts striking ecological pressures on biodiversity at local scales but also has indirect effects in distant corners of the world. We suggest that the multibillion dollar cashmere industry creates economic motivations that link western fashion preferences for cashmere to land use in Central Asia. This penchant for stylish clothing, in turn, encourages herders to increase livestock production which affects persistence of over 6 endangered large mammals in these remote, arid ecosystems. We hypothesized that global trade in cashmere has strong negative effects on native large mammals of deserts and grassland where cashmere‐producing goats are raised. We used time series data, ecological snapshots of the biomass of native and domestic ungulates, and ecologically and behaviorally based fieldwork to test our hypothesis. In Mongolia increases in domestic goat production were associated with a 3‐fold increase in local profits for herders coexisting with endangered saiga (Saiga tatarica).That increasing domestic grazing pressure carries fitness consequences was inferred on the basis of an approximately 4‐fold difference in juvenile recruitment among blue sheep (Pseudois nayaur)in trans‐Himalayan India. Across 7 study areas in Mongolia, India, and China's Tibetan Plateau, native ungulate biomass is now <5% that of domestic species. Such trends suggest ecosystem degradation and decreased capacity for the persistence of native species, including at least 8 Asian endemic species: saiga, chiru (Pantholops hodgsoni), Bactrian camel (Camelus bactrianus), snow leopard(Panthera uncia), khulan(Equus hemionus), kiang (E. kiang), takhi (E. przewalski), and wild yak (Bos mutus). Our results suggest striking yet indirect and unintended actions that link trophic‐level effects to markets induced by the trade for cashmere. Globalización del Mercado de Cachemira y la Declinación de Mamíferos Mayores en Asia Central  相似文献   

18.
The high conservational value of the lichen-rich vegetation and landscape of the marine foreland Ørkenen on the isle of Anholt is treated from a Danish as well as a European perspective. The sensitivity of the lichen-rich vegetation to physical disturbance is emphasized. The impact of invasive species such asPinus mugo as well as the effect of atmospheric deposition of nutrients on the heaths at Anholt is described. Considerations related to the development of a management plan for Ørkenen are presented.  相似文献   

19.
Summary The attraction of Old World leaf beetles in the genusAulacophora to kairomones and parakairomones which are effective lures for New WorldDiabrotica andAcalymma were investigated. Beetles captured on sticky traps baited with single and multicomponent lures were no different from the control traps for two species ofAulacophora. Yellow colored traps and squash blossoms are attractive toAulacophora beetles which detect sub-microgram quantities of cucurbitacins on silica gel. Leaf feeding behavior and flight activity data are correlated with varietal preference of threeAulacophora species. The common response byDiabrotica andAulacophora to cucurbitacins reinforces the two groups' coevolutionary association with the Cucurbitaceae. The apparent lack of a common response toCucurbita blossom volatiles suggests recent evolutionary pathways are substantially different for these two groups of beetles.  相似文献   

20.
Invasive non-native species are important drivers of ecosystem change, yet the driving forces of biological invasions themselves are poorly understood. Such information is essential to ensure policies focus on the most relevant drivers, and that future scenarios capture the full range of potential outcomes for invasive non-native species. I carried out a bibliometric analysis of articles published from 2000 to 2020 that address either invasive non-native species or biodiversity and ecosystem services and that also mention 1 or more drivers of ecosystem change. I examined 5 indirect drivers (demographic, economic, governance, sociocultural, and technological) and 6 direct drivers (climate change, invasive non-native species, land-use or sea-use change, natural hazards, pollution, and resource extraction). Using the Web of Science core collection of citation indexes, I undertook searches of article titles and keywords and retrieved 27,462 articles addressing invasive non-native species and 110,087 articles dealing with biodiversity or ecosystem services. Most research to date on biological invasions as well as on biodiversity and ecosystem services has focused on anthropogenic direct drivers of ecosystem change rather than indirect drivers. Yet currently, less than 18% of articles addressing biological invasions examined drivers of ecosystem change, a similar level to that found over 20 years ago for biodiversity or ecosystem services. Knowledge of the drivers of biological invasions is limited, emphasizes tractable drivers over those that require an interdisciplinary approach, and is biased toward developed economies. Drivers generally deemed important for biological invasions, such as governance and resource extraction, accounted for less than 2% of research effort. The absence of a systematic understanding of the forces that drive invasive non-native species and how they interact means that attempts to mitigate or forecast biological invasions are likely to fail. To address biological invasions requires a much better orientation of national and international research on drivers in relation to both their actual importance as well as their policy relevance.  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