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 15 毫秒
1.
The effect of Kilmezskii pesticide burial on the condition of zoobenthos of Osinovka and Loban’ rivers (the Vyatka River basin, Kirovskaya oblast) is reviewed. A faunistic list of water invertebrates in these rivers is published for the first time, qualitative and quantitative indices of zoobenthos development are given, and the condition of watercourses is assessed using bioindicative methods. The peculiarities of benthic communities of the Osinovka River and its tribute, i.e., a significant impoverishment of species composition, the simplification of structural organization, and low bioindicative indices, allow us to assume that the burial has a negative effect on zoobenthos condition.  相似文献   

2.
This project was undertaken as the initial monitoring program to determine if mosquito adulticides applied along the Florida Keys cause adverse ecological effects in the Florida Keys National Marine Sanctuary (FKNMS). The study monitored the distribution and persistence of two mosquito adulticides, permethrin and dibrom (naled), during three separate routine applications by the Florida Keys Mosquito Control District. The approach was to determine if toxic concentrations of the pesticides entered the FKNMS by aerial drift or tidal transport. The amount of pesticide entering the FKNMS by way of aerial drift was monitored by collection on glass fiber filter pads, set on floats in a grid pattern on either side of the FKNMS. Permethrin was recovered from filter pads on the leeward side for each of the three applications, ranging from 0.5 to 50.1 microg/m(2) throughout the study. Tidal current transport was monitored by collection of surface and subsurface water samples at each grid site. Tidal transport of naled and dichlorvos (naled degradation product) was apparent in the adjacent waters of the FKNMS. These compounds were detected in subsurface, offshore water at 0.1 to 0.6 microg/1, 14 hr after application. Permethrin was not detected in offshore water samples; however, concentrations ranging from 5.1 to 9.4 microg/l were found in surface water from the canal system adjacent to the application route. Comparison of the observed environmental concentrations with toxicity data (permethrin LC-50, 96 hr for Mysidopsis bahia = 0.02 microg/l) indicated a potential hazard to marine invertebrates in the canals with possible tidal transport to other areas.  相似文献   

3.
Chakrabarty D  Das SK 《Bio Systems》2007,90(2):309-313
The influence of bioturbation caused by common carp fry in 5 L jars (5 L each) in the laboratory and in 150 L outdoor vats in increasing the fertilizer value of phosphate rock was evaluated. Soluble reactive phosphate (SRP) was determined to quantify the effects of bioturbation, fish excrements and soil. The level of SRP was always lowest in the control series. Introduction of common carp fry resulted in a net increase of 0.09-0.10 mg L(-1) of SRP attributable to the effect of fish excrement. Bioturbation caused by common carp resulted in a 64.8-90% influx of phosphate from bottom soil in the presence of phosphate rock but only about 6.3-7.2% in the absence of phosphate rock. The bioturbation that occurred in these treatments resulted in a significant release of phosphorous into the overlying water from the apatite source. The results confirm the benefits of the application of environmentally friendly phosphate rock in fish farming ponds at low cost.  相似文献   

4.
OBJECTIVE: To throw light on cytologic findings as a possible mode of diagnosis of lymphatic filariasis. STUDY DESIGN: Filariasis has worldwide distribution, but lymphatic filariasis predominantly affects tropical and subtropical regions. Demonstration of microfilaremia, the specific test for diagnosis of lymphatic filariasis, often shows false negative results in endemic areas. The present study, done in an endemic area, showed the presence of microfilariae or adult worms of Wuchereria bancrofti in fine needle aspirates collected from amicrofilariaemic cases. In a few cases the discovery was incidental. A total 4,534 cases undergoing cytologic evaluation were carefully screened for the presence of adult worms or larvae, irrespective of clinical diagnosis. Microfilariae were demonstrated in both clinically suspected cases of filariasis and asymptomatic cases. RESULTS: A total of 1 positive cases were found; in 4 cases the clinical diagnosis was lymphatic filariasis, and 7 cases were asymptomatic. All 11 cases were amicrofilariaemic. CONCLUSION: Various sophisticated investigations are used for diagnosis of lymphatic filariasis without microfilaremia. Fine needle aspiration cytology, being a cheap, simple and easy procedure, may have some role in this field, but further detailed studies are needed before any final claim.  相似文献   

5.
In the peanut production, the applications of herbicides and fungicides are a common practice. In this work, studies done under field conditions demonstrated that pesticides affected negatively the number and nitrogenase activity of diazotrophic populations of soil. Agrochemical effects were not transient, since these parameters were not recovered to pre-treatment levels even 1 year after pesticides application. Results obtained from greenhouse experiments revealed that the addition of herbicide or fungicides diminished the free-living diazotrophs number reaching levels found in soil amended with the pesticides and that the number of symbiotic diazotrophs was not affected by the insecticide assayed. The soil nitrogenase activity was not affected by fungicides and glyphosate. The effect of pesticides on the nitrogen-fixing bacteria diversity was evaluated both in field and greenhouse experiments. Analysis of clone libraries generated from the amplification of soil nifH gene showed a diminution in the genetic diversity of this bacterial community.  相似文献   

6.
The cyanobacterium Nostoc strain ATCC 53789, a known cryptophycin producer, was tested for its potential as a source of natural pesticides. The antibacterial, antifungal, insecticidal, nematocidal, and cytotoxic activities of methanolic extracts of the cyanobacterium were evaluated. Among the target organisms, nine fungi (Armillaria sp., Fusarium oxysporum f. sp. melonis, Penicillium expansum, Phytophthora cambivora, P. cinnamomi, Rhizoctonia solani, Rosellinia, sp., Sclerotinia sclerotiorum, and Verticillium albo-atrum) were growth inhibited and one insect (Helicoverpa armigera) was killed by the extract, as well as the two model organisms for nematocidal (Caenorhabditis elegans) and cytotoxic (Artemia salina) activity. No antibacterial activity was detected. The antifungal activity against S. sclerotiorum was further studied with both extracts and biomass of the cyanobacterium in a system involving tomato as a host plant. Finally, the herbicidal activity of Nostoc strain ATCC 53789 was evaluated against a grass mixture. To fully exploit the potential of this cyanobacterium in agriculture as a source of pesticides, suitable application methods to overcome its toxicity toward plants and nontarget organisms must be developed.  相似文献   

7.
砷矿区农田土壤微生物群落碳源代谢多样性   总被引:3,自引:0,他引:3  
采用Biolog方法研究了砷(As)矿区农田土壤微生物碳源利用多样性及其与土壤化学性质的关系.结果表明:3种土壤的N、P、K、有机质(OM)、Cu和Zn全量依次为中As>高As>低As土壤.中As和高As土壤微生物平均吸光度以及多样性指数(H'、D、U)显著高于低As土壤.主成分分析与生理碳代谢指纹图谱分析表明,中As和高As土壤微生物对糖类、氨基酸类等碳源的利用程度显著高于低As土壤.典范对应分析显示,影响土壤微生物群落碳源代谢的主要有全P、OM、全Pb、全Zn、全N和pH,全As并不是最主要的影响因子.可见,养分是影响长期污染土壤微生物群落结构和功能多样性的主要因素.  相似文献   

8.
介绍手性源、手性池和手性分子化合物的基本概念;由手性池化合物制备手性衍生物;比较了手性化合物生物加工与化学加工过程的优、缺点,寻求高效、经济和最合理的综合工艺流程。  相似文献   

9.
Zhang F  Ma H  Chen J  Li GD  Zhang Y  Chen JS 《Bioresource technology》2008,99(11):4803-4808
Microporous carbon (MC) with a high surface area has been prepared from cornstalks through carbonization and KOH activation. The surface area of the obtained product varies to some extent but the pore size of the material remains within the micropore region as the concentration of KOH activating agent is increased. The MC we prepared exhibits H2 adsorption capacities up to 4.4 wt% at 77K and this material is also able to adsorb considerable amounts of CH4 and CO2. The high adsorption capacities for gases are attributed to the relatively narrow pore size and the high surface area of the porous carbon material.  相似文献   

10.
樱草杜鹃中的黄酮类化合物   总被引:5,自引:0,他引:5  
从樱草杜鹃(Rhododendron primulaeflorum)地上部分的乙醇提取物中分离得到10个黄酮类化合物,经理化性质及波谱分析,鉴定为杜鹃素(1)、4’,5,7-三羟基-8-甲基黄烷酮(2)、二氢山柰酚(3)、异鼠李素(4)、槲皮素(5)、陆地棉苷(6)、瑞诺苷(7)、(2R,3R)-花旗松素-3—O-α-L-吡喃阿拉伯糖苷(8)、(2R,3S)-花旗松素-3—O-α-L-吡喃阿拉伯糖苷(9)、(2S,3R)-花旗松素-3-O-α-L-吡喃阿拉伯糖苷(10)。所有化合物均为首次从该植物中分得。  相似文献   

11.
The importance of agricultural land use activities for supplying nutrients (N, P) to the Chesapeake Bay is examined and nutrient sources for a typical agricultural hill-land watershed within the Chesapeake Basin are identified and assessed. Based on up to 30 years of experimental and monitoring data, the outflow, N, and P exported from this Pennsylvania watershed is examined in terms of critical source areas. Most of the surface runoff and P export occurs from areas near the stream. About 90% of the algal-available P exported in outflow was generated during the largest 7 storms/year. In contrast, nearly all the nitrate (NO3) exported originated as subsurface flow entering the soil or ground water some distance from the stream, and mostly occurred during nonstorm flow periods. The NO3 export observed over the long term corresponds to the N excess computed by N balance obtained by farmer survey for agricultural land. By combining land use, hydrologic processes, watershed position, soil P status, and N balance information for agricultural land, the major source areas for P and N are predictable and identifiable. We apply these ideas and techniques to our research watershed and present the results as an example of this approach.  相似文献   

12.
Short-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening movements. SRS is attributed to the cross-bridges and is beneficial for stabilizing a joint during, e.g., postural conditions. Thus far, SRS has been estimated mainly on isolated mammalian muscles. In this study we presented a method to estimate SRS in vivo in the human wrist joint.SRS was estimated at joint level in the angular domain (N m/rad) for both flexion and extension rotations of the human wrist in nine healthy subjects. Wrist rotations of 0.15 rad at 3 rad/s were imposed at eight levels of voluntary contraction ranging from 0 to 2.1 N m by means of a single axis manipulator.Flexion and extension SRS of the wrist joint was estimated consistently and accurately using a dynamic nonlinear model that was fitted onto the recorded wrist torque. SRS increased monotonically with torque in a way consistent with previous studies on isolated muscles.It is concluded that in vivo measurement of joint SRS represents the population of coupled cross-bridges in wrist flexor and extensor muscles. In its current form, the presented technique can be used for clinical applications in many neurological and muscular diseases where altered joint torque and (dissociated) joint stiffness are important clinical parameters.  相似文献   

13.
Laccases (benzenediol: oxygen oxidoreductase, EC 1.10.3.2) are multi-copper-containing enzymes capable of catalyzing the oxidation of a wide range of phenolic and non phenolic aromatic compounds. The available data indicates that laccases from prokaryotes are promising biological tools for green chemistry based applications, especially in decolorization of industrial textile dye effluents which constitute a major threat to soil and ground water reservoirs worldwide. Another appropriate application of prokaryotic laccases is bio-bleaching of different kind of pulps where there is indiscriminate use of hazardous chlorine based chemicals for brightness of the paper. In recent years, researchers have shown interest in the identification and characterization of laccases from prokaryotic sources. This catalyst is not commonly reported from this kingdom, although prokaryotes have immense environmental adaptability and biochemical versatility. Moreover, true laccases or laccase-like enzymes exist in many gram-negative, gram-positive bacteria and actinomycetes. Corresponding genes have been identified and functionally expressed in genetically developed hosts. This review summarizes the research efforts to characterize laccases and their properties from different prokaryotic sources, including bacteria and actinomycetes.  相似文献   

14.
四齿四棱草水提取物的化学成分研究   总被引:1,自引:0,他引:1  
从四齿四棱草地上部分水煮提取物中分离得到11个化合物,通过波谱分析并与文献和标准品对照将它们分别鉴定为β-谷甾醇(1)、4-乙酰胺基乙基苯基6-O-甲基香豆酰吡喃葡萄糖基(1→2)[-βD-吡喃葡萄糖基(1→3)]-α-L-吡喃鼠李糖苷(2)、4-乙酰胺基乙基苯基6-O-甲基香豆酰吡喃葡萄糖基(1→2)[-βD-吡喃葡萄糖基(1→3)]-4-O-乙酰基-α-L-吡喃鼠李糖苷(3)、6-C--βL-吡喃阿拉伯糖基-8-C--αL-吡喃阿拉伯糖基洋芹素(4)、6,8-二-C-α-L-吡喃阿拉伯糖基洋芹素(5)a、cetylmartynoside B(6)i、somartynoside(7)a、lyssonoside(8)l、eucosceptoside B(9)、连翘苷B(10)和丁二酸(11)。其中2和3为顺反异构体的混合物。  相似文献   

15.
Forest cover products are an essential tool for land managers and policy makers. They are used at a variety of spatial scales to inform decision‐making and policy across a range of ecosystem drivers and services. This article compares three forest cover products (FCP), all of which were created using Landsat satellite imagery, but using different methodologies and covering different spatial extents that range from global to state. It also explores their use and utility across the state of Victoria, Australia. It asks the question, how interchangeable are the forest cover maps? FCP are also validated against a very high‐resolution reference data set. Overall accuracy was around 89% for the state and national FCP, and 84% for the global FCP. The global map produced the lowest estimate of total forest cover, while estimates obtained by the national and state FCP were similar across the study area. Spatially, differences, however, were apparent. The national forest cover map obtained higher estimates across most of Victoria except in the most arid region which is dominated by low open woodland. While the national and global scale forest cover maps were found to have good diagnostic ability for large area assessment and reporting, their use for land management is not optimal and can lead to gross error.  相似文献   

16.
藏东瑞香茎叶化学成分的研究   总被引:2,自引:0,他引:2  
运用各种色谱分离方法对藏东瑞香(Daphne bholua)地上部分的乙醇提取物进行分离纯化,从中分离得到12个化合物。通过波谱学数据并与已知化合物数据作比较,它们分别鉴定为:木犀草素(1)、芫花素(2)、芫花素5-O-β-D-葡萄糖苷(3)、3'-羟基-芫花素(4)、3'-甲氧基.芫花素(5)、异新狼毒素(6)、Genkwanol B(7)、Oleo-daphnone(8)、阿魏醛(9)、香草醛(10)、对羟基苯甲酸乙酯(n)移谷甾醇(12)。所有这些化合物都为从该植物中首次分离鉴定。  相似文献   

17.
Boron (B) levels were determined in the serum of 980 healthy inhabitants living in an urban area of Japan by means of inductively coupled plasma emission spectrometry (ICPES). The results showed a log-normal distribution of serum B for both sexes, although there are age-related differences. In male subjects, serum B increases rapidly up to 49 yr of age, reaching a plateau between ages 50 and 69 yr old, followed by a gradual increase up to 70 yr or older. Female subjects exhibit a gradual increase up to the age of 70 yr old. The reference value for male and female subjects was 79.8 μg/L and 67.9 μg/L, and the reference interval was 33.3–191.2 μg/L and 29.5–154.9 μg/L, respectively. The obtained reference value and interval of the nonexposed group may be useful for health screening for B exposure, either for people living in regions with high levels of B in the environment, or for workers who are exposed to this element.  相似文献   

18.
利用气相色谱法(GC-ECD)对厦门海域贝类养殖环境(海水、底质和养殖贝类)中有机氯农药六六六(HCH)和滴滴涕(DDT)的含量进行了调查分析,初步探讨了贝类养殖环境中HCH和DDT的积累和降解规律.结果表明:厦门海域不同种贝类养殖环境中HCH和DDT的积累和降解存在明显差异,主要与各种贝类的栖息环境和生理生活习性有关.贝类养殖环境中处于积累状态(Rx>1)的主要为p-HCH、δ-HCH和γ-HCH;处于降解状态(Rx<1)的主要为α-HCH.α-HCH/γ-HCH的比值≤1.0,贝类养殖环境中的HCH来源于工业品HCH和林丹,大部分HCH为长时间残留,但尚有少量林丹输入.贝类养殖区海水中DDT主要为好氧降解,底质中主要为厌氧降解.海水中的降解产物主要为DDE,(DDD+ DDE )/DDTs(p,p-DDE+p,p-DDD+o,p-DDT+p,p-DDT)的比值<0.5;底质和养殖贝类体中的降解产物主要为DDD,(DDD+DDE)/DDTs的比值>0.5,贝类养殖区底质和养殖贝类体中的DDT大部分已降解为DDD和DDE,海水中尚有少量新的DDT输入.贝类养殖环境中HCH异构体降解率的高低顺序存在一定差异,其在贝类养殖生态系中的迁移、转化过程发生了构象变化.  相似文献   

19.
By means of a box-sampler 20 moderately undisturbed sediment samples were obtained, which were subsampled on board the ship. The fauna in the upper 0–5 cm of the sediments was compared to that in the 5–10 cm layer; almost all species collected in both strata were found in the upper 0–5 cm. About 64% of the individuals and 74% of the biomass were restricted to this upper layer. A sample area of 0.5 m2 (depth 0–10 cm) was found to be sufficient to make a quantitative evaluation of the benthic community. The horizontal dispersion of the macrobenthic community was studied using the variance/mean ratio and its dependence on sample size is discussed. The abundant species occurred in patches larger than 0.06 m2 and high densities were correlated with aggregation.  相似文献   

20.
Zhong SL  Dong LM 《应用生态学报》2011,22(9):2447-2456
By using GC-ECD, the concentrations of organochlorine pesticides hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in the shellfish culture environment (sea water, sediments, and culture-shellfishes) in Xiamen sea area were analyzed, and the accumulation and degradation patterns of the HCH and DDT were preliminarily approached. In the sea area, there existed remarkable differences in the accumulation and degradation of HCH and DDT among different shellfish culture environments, being mostly associated with the habitation environment and physiological life habits of shellfish. The accumulated HCH isomers (Rx > 1) were mainly beta-HCH, delta-HCH, and gamma-HCH, whereas the degraded HCH isomers (Rx < 1) were mainly alpha-HCH. The ratio of alpha-HCH to gamma-HCH was less than or equal to 1.0, suggesting that the HCH was come from industrial HCH and lindane, most of the HCH had remained in the culture environment for a longer time, and a small amount of lindane was imported. The DDT in the sea water was aerobically degraded, its main degradation product was DDE, and the ratios of (DDD+DDE) to DDTs (p,p-DDE+p,p-DDD+o,p-DDT+p,p-DDT) was less than 0.5, whereas the DDT in sediments and shellfishes was anaerobically degraded, its main degradation product was DDD, and the ratios of (DDD+DDE) to DDTs was greater than 0.5, suggesting that there was a small amount of DDT newly imported in the sea water, and most DDT in sediments and shellfishes were already degraded and transformed into DDD and DDE. There were definite differences in the degradation rates of HCH isomers in the culture environment, suggesting the conformational change of HCH in its transformation processes in the shellfish culture ecosystem.  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