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551.
富营养化水体中致嗅物质的产生及其去除工艺 总被引:1,自引:0,他引:1
提出生物法去除水中的异臭异味物质是一种效率高而费用低廉的有效措施,并对致嗅物质的去除机理进行了探讨。 相似文献
552.
Interaction of DNA with aromatic hydrocarbons fraction in atmospheric
particulates of Xigu District of Lanzhou, China 总被引:1,自引:0,他引:1
Voluminously epidemiological studies show that the relationships exist between the air pollution and human health and cancer. Aromatic hydrocarbons(AHs)in air form a large class of organic pollutants,which are widely in environment and many of them are known to be carcinogenic and/or mutagenic and contribute to ambient air pollution.In the past decades,bioassays mainly have been used to evaluate the toxicity of chemical mixtures in atmospheric particulates or aqueous environment.However,it is well known that the covalent complexes formed by carcinogens with DNA may be exert negative results in bioassay.So the main aim of this paper is to develop an evaluation method of toxicity effects of chemical mixtures in atmospheric particulates from chemical standpoint.In this study,the in vitro interaction of the AHs with DNA was investigated by absorption,fluorescence and resonance light scattering (RLS)spectroscopic techniques.The results showed that the AHs in the atmospheric particulates could combine with calf thymus DNA(ctDNA)and herring sperm DNA(hsDNA)without being activated or metabolized by organism,respectively.Intercalation may be present in the mechanism of interaction.The binding constants of the AHs with ctDNA and hsDNA were 2.5×10~2 and 2.0×10~3, respectively,which indicated that the interaction of the AHs with hsDNA is stronger than that with ctDNA.In addition,the relationships of dose-effect between the total mole concentration of chemical components and the ability of binding ctDNA and hsDNA were confirmed.This research made it possible to study the toxicity effects of chemical mixtures in atmospheric particulates by chemical method.It is believed that the composition and contents of unknown AHs and the interaction of DNA with AHs in atmospheric particulates of Xigu District of Lanzhou City,China are first reported in the past twenty years. 相似文献
553.
2001-03-09蒙城地震台地磁磁变仪CB-3(观测仪,备份仪)同时出现三个分量动线的跳动,分析表明蒙城地震台地磁总强度F、 垂直强度Z发生变化。 其原因可能是强电流作用下,地下介质电性变化所致。 相似文献
554.
This paper considers the use of meiofauna (benthic metazoa 45 to 500 m in size) as biological indicators for monitoring marine environmental health. To date, this abundant and ubiquitous group of invertebrates has been largely neglected in applied sampling programmes; instead, emphasis has been placed upon more conspicuous biological components such as seagrass, macrofauna and epiphytes. In an attempt to redress this balance, this paper sets out three objectives: (1) to explain the reasons for selecting biological response indicators from across the whole spectrum of phylogenetic organisation, (2) to summarise those aspects of meiofaunal life-history and demography that render this group suitable for monitoring anthropogenic pollution and disturbance, (3) to suggest how to optimise the inclusion of meiofauna in monitoring programmes so that they provide maximum information for management purposes. To achieve these objectives the environmental impact assessment framework of Ward and Jacoby (1992) is adopted as a matrix into which the relevant components of meiofaunal ecology are fitted. Using this matrix, meiofauna are shown to have advantages that include their sessile habit, high species diversity, short generation time, direct benthic development and ubiquitous distribution. Disadvantages include their small size, high level of spatial and temporal variability, the potential cost of sample processing and the limited taxonomic literature accessible to non-specialist workers. The paper concludes with a discussion of sampling strategies and methods of analysis that may be used to efficiently incorporate meiofauna as biological response indices into environmental monitoring. Emphasis is placed on cost-effective techniques such as taxonomic minimalism. 相似文献
555.
Relationships of Human Disturbance, Bird Communities, and Plant Communities Along the Land-Water Interface of a Large Reservoir 总被引:1,自引:0,他引:1
We examined the relationships of humanactivity, bird communities, and plant communities along theland-water interface of Lake Texoma, a large human-madereservoir on the Texas-Oklahoma border. Measurements ofhuman activity, plant surveys, and bird surveys wereperformed at 40 paired transects, one with humandisturbance, the other undisturbed. Both principalcomponents and correspondence analyses of bird-survey dataseparated disturbed sites from paired undisturbed sites, andtypical disturbance-tolerant species from those lesstolerant of human activity. Compared to undisturbed sites,disturbed sites tended to have more individual birds persurvey, pavement, and mowed lawns, and less canopy,vegetation volume, and vegetation vertical diversity. Aprincipal components analysis of quantitative disturbancemeasurements revealed that most bird and plant measures werehighly correlated with the first disturbance component. However, the correlation between birds and human activitywas much stronger than that between birds and plants, orbetween plants and disturbance. Our data suggest that bird-species composition is regulated more by human activity thanby plant-community composition. Also, in this system, birdcommunities are a better choice than plant communities toindex the effect of human disturbance. To maintain regionaldiversity of both birds and plants, undisturbed areas shouldbe maintained around reservoirs. 相似文献
556.
通过GC-MS分析,研究了气化温度和气料比S/B(水蒸气与污泥的质量比)对污泥气化焦油中芳香烃、含氮化合物、含氧化合物和含硫化合物分布特征的影响变化规律.结果表明:污泥气化焦油中芳香烃的化学组分主要为菲类、萘类、芴类和联苯类化合物,其中S/B值1.1、1.5和1.9时菲类和萘类化合物的产率在850℃均达到最大值,S/B值1.5和1.9时芴类产率随气化温度的升高而呈先升高后降低,而800℃时联苯类产率则随S/B值的增加而呈先升高后降低,其最高产率为1.284g/kg.含氮化合物以吲哚类化合物为主,其产率在S/B值为1.5和1.9时均随气化温度的升高而呈降低趋势;含氧化合物中主要为酚类化合物,其产率在750℃时随S/B值的升高而升高,其最高产率3.103g/kg;含硫化合物主要为4,4'-双(四氢噻喃),且仅在850℃、S/B值为1.9气化条件下检出产率为0.263g/kg的萘并[1,2-b]噻吩. 相似文献
557.
塔里木盆地北缘绿洲4种土地利用方式土壤有机碳组分分布特征及其与土壤环境因子的关系 总被引:3,自引:0,他引:3
为明确干旱区土壤有机碳各组分分布状况,进而合理地开发与利用,解决土地利用效率低下问题,以塔里木盆地北缘盐碱地、天然林、沙地、30 a棉田这4种不同土地利用方式土壤为研究对象,分析不同土地利用方式土壤有机碳、微生物量碳、可溶性有机碳、易氧化有机碳的分布状况,结合冗余分析探索其与土壤环境因子的关系.结果表明,SOC在天然林表现出最高值(1.92 g·kg~(-1)),在沙地随土层增加而增加,在其他土地利用类型整体呈现下降趋势;MBC在天然林表现出最高水平,且随土层深度增加而降低,在其他土地利用类型无明显变化趋势.DOC含量最高值和最低值分别出现在天然林和30 a棉田的80~100 cm层(分别为143.23 mg·kg~(-1)和30.00 mg·kg~(-1)),在天然林中随土层深度增加而增加,在盐碱地中随土层深度增加而降低且不同土层含量均表现出显著差异(P0.05).EOC含量在不同土地利用类型和不同土层中未表现出明显规律.将各有机碳组分进行敏感性分析得出:MBC对不同土层最为敏感,DOC对土地利用变化最为敏感.通过冗余分析得出各有机碳组分与土壤含水量、全氮、p H呈正相关关系,与土壤容重、电导率呈负相关关系.土壤环境因子对各碳组分含量的重要性排序为:土壤容重含水量电导率土壤氮p H,即容重和含水量为影响干旱区有机碳组分的主要因子. 相似文献
558.
559.
Sigal Lahav Victoria Soroker Robert K. Vander Meer Abraham Hefetz 《Behavioral ecology and sociobiology》1998,43(3):203-212
This study compares two basic models for the origin and maintenance of colony gestalt odor in the polygynous ant species
Cataglyphis niger. In the first model, queens are centers of de novo biosynthesis and distribution of recognition odors (“queen-centered” model);
in the second, colony odors are primarily synthesized and distributed by workers (“worker-centered” model). We tested the
behavioral patterns that are predicted from each model, and verified by biochemical means the distributional directionality
of these signals. Encounters between nestmates originating from split colonies were as amicable as between nestmates from
non-split colonies; queenless ants were as aggressive as their queenright nestmates, and both were equally aggressed by alien
ants. These results indicate that queens have little impact on the recognition system of this species, and lend credence to
the worker-centered model. The queen-centered model predicts that unique queen substances should be produced in appreciable
quantities and that, in this respect, queens should be more metabolically active than workers. Analysis of the chemical composition
of postpharyngeal glands (PPGs) or cuticular extracts of queens and workers revealed high similarity. Quantitatively, queens
possessed significantly greater amounts of hydrocarbons in the PPG than workers, but the amount on the thoracic epicuticle
was the same. Queens, however, possess a lower hydrocarbon biosynthesis capability than workers. The biochemical evidence
thus refutes the queen-centered model and supports a worker-centered model. To elucidate the directionality of cue distribution,
we investigated exchange of hydrocarbons between the castes in dyadic or group encounters in which selective participants
were prelabeled. Queens tended to receive more and give less PPG content, whereas transfer to the epicuticle was low and similar
in all encounters, as predicted from the worker-centered hypothesis. In the group encounters, workers transferred, in most
cases, more hydrocarbons to the queen than to a worker. This slight preference for the queen is presumably amplified in a
whole colony and can explain their copious PPG content. We hypothesize that preferential transfer to the queen may reflect
selection to maintain her individual odor as close to the average colony odor as possible.
Received: 4 November 1997 / Accepted after revision: 5 February 1998 相似文献
560.
Mirsaleh Mirmohammadi Javad Gholamnejad Vahidoddin Fattahpour Pejman Seyedsadri Yousef Ghorbani 《Journal of environmental management》2009
This paper depicts the method used to quantify the environmental impact of mining activities in surface mine projects. The affected environment was broken down into thirteen components, such as Human health and immunity, Surface water, Air quality, etc. The effect of twenty impacting factors from the mining and milling activities was then calculated for each Environmental Component. Environmental assessments are often performed by using matrix methods in which one dimension of the matrix is the “Impacting Factor” and the other one is the “Environmental Components”. For the presented matrix method, each Impacting Factor was first given a magnitude between −10 and 10. These factors are used to set up a matrix named Impacting Factor Matrix, whose elements represent the Impacting Factor values. The effects of each Impacting Factor on each Environmental Component were then quantified by multiplying the Impacting Factor Matrix by Weighting Factor Matrix. The elements of the weighting factors matrix reflect the effects of each Impacting Factor on each Environmental Component. The outlined method was originally developed for a mining and milling operation in Iran, but it can successfully be used for mining ventures and more general industrial activities in other countries in accordance to their environmental regulations and laws. 相似文献