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1.
一般系统理论不能用数列建立微分型的动态模型.本文基于灰色系统理论的生成数、灰导数、灰微分方程等观点和方法建立了宜昌市工业废水排放量微分方程预测模型.利用它预测了宜昌市工业废水的排放量及其变化趋势.  相似文献   

2.
城市水污染的原因,简单地讲,是城市人口与工业增长的后果,必须从城市生态角度出发,研究城市人口—工业增长—水环境系统的相互关系和相互影响,才能有效地制订控制水污染的对策,制订出切实可行的整体规划.而系统模拟是规划的基本手段,规划的目的是从宏观上协调社会发展、经济发展和水环境保护三者间的关系,寻求最有效的城市发展策略.污染控制规划的基本任务在于如何确保环境建设与城市建设得  相似文献   

3.
本文对天津市的水环境质量现状和存在的主要环境问题进行了系统分析,根据天津市污染防治长期规划,从建设工业水污染防治体系的目标出发,提出了解决城市工业废水污染控制问题的对策,方法和相应措施。并针对水资源严重匮乏地区的经济与环境协调发展问题,进行了研究和探讨。  相似文献   

4.
本文用系统工程方法进行河网地区小城镇水质最优规划.研究选择震泽镇作为典型,对现有水质规划方法加以推广,得到了河网水质模型建模的改进方法,提出求解以此模型为基础的河网水质线性问题的分解—协调算法.通过对典型镇环境现状的系统分析结果,提出了小城镇控制水污染的规划技术要点,以及水环境—经济系统协调发展对策  相似文献   

5.
本文依据国家‘六·五”科技攻关项目“天津市城市生态系统与污染综合防治的研究”、“公元2000年天津市污水量预测和城市污水控制对策研究”及“天津市工业废水处理设施效益分析”撰写的。据此提出了天津市污水综合治理规划及天津市水污染综合防治的技术经济政策。  相似文献   

6.
城市降雨径流水质污染分析   总被引:21,自引:0,他引:21  
目前我国对一些小流域的农业区面源污染积累较多经验,对城市面源污染的研究比较少,这是因为随着城市化进程的加速,这是人类在城市上的活动能力较农业区大幅度地增加,从而导致城市地面污染种类繁多复杂。本文通过应用径流形成原理理论对其进行初步分析,提出现行适用的控制城市径流污染的方法为工程和非工程的两大类。  相似文献   

7.
以重庆市四面山4种森林群落为研究对象,选取林冠截留率、林地土壤毛管孔隙度、林地土壤非毛管孔隙度和林地0~20 cm土壤抗冲刷系数为分析指标,运用灰色关联度法对4种森林群落的面源污染控制功能进行研究.结果表明:在4种森林群落中作为天然林的楠竹林灰关联度值最大为0.887 7,面源污染控制功能最好,其次是人工阔叶林(0.7794)和人工混交林(0.6992),人工针叶林(0.636 1)面源污染防控能力相对较弱.在人工林方面,阔叶林灰关联度值最大为0.7794,面源污染防控能力最好,其次是针阔混交林(0.699 2),针叶林灰关联度值最低为0.636 1,其面源污染防控能力较弱.  相似文献   

8.
用排放情景分析系统研究北京市机动车污染问题   总被引:4,自引:0,他引:4  
针对北京市动车污染非常严重,机动车排放控制涉及的方面较多,解决起来比较复杂的特点,开发了城市机动车排放情况分析系统,以国内外的先进理论和技术为基础,采用系统化的方法研究这个问题,对北京市未来车污染控制的几种情况进行了分析和比较,证明了北京市目前实施新排放标准,采用车辆定期报废制度对控制污染的巨大作用,提出进一步强化I/M制度,完善在用车监测维修体系等控制机动车污染的具体方法。  相似文献   

9.
重污染河道浮游动物种群的特点   总被引:2,自引:0,他引:2  
苏州城市河道水情复杂,氮磷浓度较高,属于重污染的滞流水体.通过对试验区南园水系为期1a的调查研究表明:该河段共有浮游动物33种,其中原生动物4种,轮虫类24种,枝角类4种,桡足类1种.各河段浮游动物年平均密度为678 ind·L-1,生物量为56.028 mg·L-1.从种类数来看,轮虫类大于原生动物大于枝角类大于桡足类.从密度看,全年平均以轮虫最多,其次为原生动物,桡足类最少.从生物量看,以枝角类最高,桡足类次之,原生动物最少.从季节变化来看,春夏季较多,秋冬季较少.优势种为轮虫类和枝角类,这些种类极耐有机污染,耐低溶氧.在苏州古城区重污染河道中,浮游动物的总量与水体理化指标及浮游植物的数量等均没有线性相关性(差异显著,p<0.05),这可能与苏州城市河道污染较重有关.城市河道特殊的水域环境决定了浮游动物种群的形成、演变及其发展都有其特殊性.探讨了重污染的城市河道的浮游动物种类组成特点,提出了控制某些优势种群发展的设想,为改善河道水环境提供了理论依据.  相似文献   

10.
城市自然生态空间的价值评估及规划启示   总被引:2,自引:0,他引:2  
城市自然生态空间是城市生态文明建设重要的物质基础。在规划过程中,应该将城市自然生态空间的生态价值评估作为城市规划的重要理论基础,通过相应的规划方法引导城市生态化建设和品质提升。文章通过对城市自然生态空间的界定,以及对城市自然生态空间生态价值评估的理论模型的研究,提出对规划建设的启示:积极构建城市自然生态空间统一的评估指标体系和建立适应中国本土的动态评估模型能够理性的指导城市的生态化建设,同时通过对城市自然生态空间的价值评估能够科学制定城市生态调控政策和正确引导公共参与城市生态化建设。  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.
Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network.  相似文献   

13.
Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in either-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.  相似文献   

14.
The politics of development includes subtexts of choice, as underpinned by community consensus (or lack of it), against the larger backdrop of a liberal democracy, with its intricate power structures that influence the choice of concepts and often lead to complicity rather than consent. A dilemma exists between the understanding of field-level practitioners and that of academics, whose understandings of progress differ. Progress can (and often does) imply long-term change across generations whereas development is often more a matter of crisis management and delivering tangible results to end-users. This makes it a bone of contention across political systems, irrespective of local or global dynamics. Development can emerge as a tool to be wielded for power and further political mileage at the expense of progress. Progress cannot be studied as a counterpoint to development as the sense of history is often missing in development interventions. Development tends to be piecemeal as its very logic often stems from the rationale of power. This is not to suggest, however, that development is only about politics; it is definitely more than the politics of everyday life and involves all of civil society that requires its critical and immediate attention. In this sense, it has become a priority for politicians with an underlying agenda designed to out-manouevre dissent and all statements of protest.  相似文献   

15.
As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.  相似文献   

16.
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   

17.
Abstract: In the United States, as elsewhere, a growing debate pits national energy policy and homeland security against biological conservation. In rural communities the extraction of fossil fuels is often encouraged because of the employment opportunities it offers, although the concomitant itinerant workforce is often associated with increased wildlife poaching. We explored possible positive and negative factors associated with energy extraction in the Greater Yellowstone Ecosystem (GYE), an area known for its national parks, intact biological diversity, and some of the New World's longest terrestrial migrations. Specifically, we asked whether counties with different economies—recreation (ski), agrarian (ranching or farming), and energy extractive (petroleum)—differed in healthcare (gauged by the abundance of hospital beds) and in the frequency of sexual predators. The absolute and relative frequency of registered sex offenders grew approximately two to three times faster in areas reliant on energy extraction. Healthcare among counties did not differ. The strong conflation of community dishevel, as reflected by in‐migrant sexual predators, and ecological decay in Greater Yellowstone is consistent with patterns seen in similar systems from Ecuador to northern Canada, where social and environmental disarray exist around energy boomtowns. In our case, that groups (albeit with different aims) mobilized campaigns to help maintain the quality of rural livelihoods by protecting open space is a positive sign that conservation can matter, especially in the face of rampant and poorly executed energy extraction projects. Our findings further suggest that the public and industry need stronger regulatory action to instill greater vigilance when and where social factors and land conversion impact biological systems.  相似文献   

18.
Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.  相似文献   

19.
A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.  相似文献   

20.
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   

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