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1.
沈阳市农田土壤农药残留水平   总被引:12,自引:0,他引:12  
对沈阳市农田(水田、旱田、菜田)土壤中农药残留调查表明,禾大壮、丁草胺、敌百虫、辛硫磷、阿特拉津、乐果、氧化乐果、溴氰菊酯、1605残留量测定结果均低于检出限。六六六残留几何平均水平为0.011mg/kg,DDT为0.039mg/kg;旱田、水田六六六异构体的残留主要是β-BHC,DDT异构体的残留量主要是p,p'-DDE。  相似文献   

2.
本试验采集了湖南省八种主要母质发育的23个农田土壤耕层样本,其中水田土壤16个,旱地土壤7个.将土壤氮分为七级.即交换性NH4+十NO3-,水解性NH4+,氨基糖氮,可溶性碱稳定态氮,酸溶性腐殖质态氮,固定态NH4+,难溶性腐殖质态氮。分析结果表明,土壤中交换性NH4+十NO3-的含量为22.0土9.0mg/kg,占全氮的1.7土0.7%;水解性NH4+为324.4土109.5mg/kg,占全氮的23.9±5.6%;氨基糖氮为118.9土43.0mg/kg,占全氮的9.1土3.2%;可溶性碱稳定态氮为497.1土205.8mg/kg,占全氮的36.2土8.3%;酸溶性腐殖质态氮为29.2土10.2mg/kg,占全氮的13土0.8%;固定态NH4+为47.2土24.3mg/kg,占全氮的3.6±1.7%;难溶性腐殖质态氮为341.3土270.8mg/kg,占全氮的22.2土11.6%。  相似文献   

3.
单甲脒农药对土壤微生物种群和土壤酶活性的影响   总被引:8,自引:0,他引:8  
研究了单甲脒(N'-2,4-二甲苯基-N-甲基甲脒,简称DMA)对土壤微生物种群和土壤酶活性的影响.田间试验表明,喷洒单甲脒盐酸盐(DMAH)于棉花植株对土壤微生物种群和土壤酶活性无明显影响.实验室试验表明,投加DMAH于土壤对土壤微生物种群有不同的抑制作用;当DMAH在土壤中的浓度为20mg/g时,好氧异养菌总量开始降低,硝化细菌和放线菌、真菌的土壤DMAH抑制浓度分别为0.5mg/g和0.1mg/g.DMAH对土壤酶活性的影响亦不相同,脱氢酶对土壤中DMAH含量为10mg/g时其活性即有明显的减弱,而过氧化氨酶对DMA的耐受性相当高,其活性的抑制浓度达500mg/g.试验还证明了土壤中DMA的微生物降解作用.当DMA在土壤中的浓度为50~500g/g时,其消解速率可从8.75mm·kg-1·d-1提高到48mg·kg-1·d-1.  相似文献   

4.
报道了夏季蔬菜中有机磷农药残留量的调查。结果表明:在西红柿、青椒和豆角中,乐果平均残留量为0.081mg/kg,甲基对硫磷为0.015mg/kg,二嗪农为0.003mg/kg,而敌敌畏在这三种蔬菜中均未检出。夏季蔬菜中农药残留量的超标率甲基对硫磷>乐果>二嗪农>敌敌畏。三种蔬菜中,豆角的有机磷农药检出率最高,其次为青椒、西红柿。  相似文献   

5.
土壤中结合态苯氧羧酸类除草剂的测定   总被引:9,自引:0,他引:9  
利用超临界CO2流体萃取的方法提取2甲4氯(MCPA),2,4-D和除草醚在三种土壤中的结合残留.结果表明,在培养200d的时间内,MCPA的结合残留量为1.0l-5.12mg·kg-1,占添加总量的2.0-10.1%;2,4-D的结合残留量为0.24-2.65mg·kg-1,占添加总量的0.5-5.3%;除草醚的结合残留量为6.53-19.30mg·kg-1,占添加总邑的12.9—38.2%.农药结合态与游离态含量的比值随时间的延长而增加.  相似文献   

6.
在扬州和聊城两地进行了除草剂异丙隆在小麦上和麦田土壤中的残留动态和最终残留量试验,结果表明,异丙隆在小麦植株和土壤中消解较快,消解半衰期分别3-4d和8-14d;收获时小麦籽粒中异丙隆残留量小于0.04mg/kg。推荐暂定异丙隆在小麦上MRL值为0.5mg/kg。25%异丙性可湿性粉剂,按7.5kg/hm^2用量,在次年早春使用,籽粒中异丙隆最终残留量不会超过MRL值,对小麦是安全的。  相似文献   

7.
DEHP在土壤和白菜中的残留及毒性分析   总被引:27,自引:0,他引:27  
庞金梅  杜荣平 《环境化学》1995,14(3):239-242
用聚氯乙烯(PVC)塑膜覆盖白菜地,收获期土壤和白菜植株中DEHP的残留量分别为2.73mg.kg^-1和3.05mg.kg^-1。借鉴国外的评价指标,对人体食用白菜后的潜在危害进行了分析认为,人每天摄入干白菜中DEHP的量〈0.05mg.kg^-1,远低于人每天可接受DEHP的安全摄入量1mg.kg^-1。  相似文献   

8.
霸螨灵在苹果和土壤中的残留动态试验   总被引:8,自引:1,他引:7  
报道了霸螨灵在苹果上残留动态的研究情况。霸螨灵在苹果果实中的原始沉积量1995年和1996年分别为0.470和90.761mg/kg,消解半衰期分别为2.5和3.5d,两年试验结果消解趋势基本一致。按推荐剂量2000倍液和高剂量1000倍液分2次和3次施药,14d后测定,霸螨灵在苹果中的残留量分别为0.098mg/kg和0.132mg/kg,不超过FAO/WHO关于霸螨灵在苹果中残留限量1mg/k  相似文献   

9.
珠江广州河段底泥中有机质、硫化物和重金属汞、铜、铅的污染监测结果表明:各种污染物的含量范围分别为有机质20.8—74.4g/kg,硫化物28.7—538mg/kg,汞0.07-0.74mg/kg,铜20.9—101mg/kg,铅14.2—917mg/kg;它们在沿程各断面的分布表现为上游往中游递增,而中游向下游递减,基本上以猎德、广纸和黄沙三个断面的污染最严重;各种污染物的污染程度顺序是硫化物>汞>铜>铅。相关分析表明:汞、铜与有机质和硫化物的相关关系均达到极显著水平。说明随着底泥中有机质和硫化物积累的增加,汞、铜的富集量相应增加,污染加重。  相似文献   

10.
固定化微生物厌氧移动床——好氧法处理偶氮染料废水   总被引:9,自引:0,他引:9  
在分离获得的三株高效脱色菌组成的混合脱色菌种基础上,利用固定化微生物 氧移动床与好氧生物氧化法结合的工艺处理人工配制的偶氮染料废水,在15-18℃的条件下,当原水COD浓度为1500mg/L=1580mg/L,色度400倍,厌氧水为停留时间8h,好氧容积负荷率4.0kgCOD/m^3(填料),d时,色度及COD的去除率分别为96.9%及93.4%。  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.
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   

16.
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   

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.
Assessing causes of population decline is critically important to management of threatened species. Stochastic patch occupancy models (SPOMs) are popular tools for examining spatial and temporal dynamics of populations when presence–absence data in multiple habitat patches are available. We developed a Bayesian Markov chain method that extends existing SPOMs by focusing on past environmental changes that may have altered occupancy patterns prior to the beginning of data collection. Using occupancy data from 3 creeks, we applied the method to assess 2 hypothesized causes of population decline—in situ die-off and residual impact of past source population loss—in the California red-legged frog. Despite having no data for the 20–30 years between the hypothetical event leading to population decline and the first data collected, we were able to discriminate among hypotheses, finding evidence that in situ die-off increased in 2 of the creeks. Although the creeks had comparable numbers of occupied segments, owing to different extinction–colonization dynamics, our model predicted an 8-fold difference in persistence probabilities of their populations to 2030. Adding a source population led to a greater predicted persistence probability than did decreasing the in situ die-off, emphasizing that reversing the deleterious impacts of a disturbance may not be the most efficient management strategy. We expect our method will be useful for studying dynamics and evaluating management strategies of many species.  相似文献   

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