共查询到20条相似文献，搜索用时 31 毫秒
1.
John E. Bardach 《GeoJournal》1985,10(3):221-232
Aquaculture, the farming and husbandry of freshwater and marine organisms furnishes about 12% of the food man obtains from the waters of the globe. It is most important in Asia and has grown rapidly in the last decade. The development of aquaculture must rely on control over production sites, in most cases, and on the application of various bio-technical inputs. It dates back to antiquity and has relied on fish and molluscs as its mainstays. Freshwater species predominate among the former but increasing competition for the freshwater resources of the globe indicate that the cultivation of marine species (mariculture) will be of increasing importance. Many species are partly or fully cultured with very few having assumed domesticated, i.e., genetically improved status. The world's tropics with their warmer climate present greater development potential for aquaculture than the temperate zone, a fact that promises to make it especially valuable in policies to improve the diets of developing nations. An overview is given here over species and methods of aquaculture with the latter seen as a continuum having at one pole feedlot types of management with strong control over environmental variables and high inputs, also resulting in high yields, and at the other an approach that could be likened to pasturage. Feeding is not excluded in it but recycling and astute steering of ecological processes are equally if not more important management mechanisms here. Biological and engineering research in aquaculture is being pursued widely. However, pollution, site competition, security of tenure to a site and the like have to be addressed in equal measure for aquaculture to hold its promise of furnishing important quantities of high quality protein food. 相似文献
2.
Nonnative species cause economic and ecological impacts in habitats they invade, but there is little information on how they spread and become abundant. This is especially true for nonnative species in native Zostera marina eelgrass beds in coastal British Columbia, Canada, which play a vital role in estuarine ecosystems. We tested how nonnative species richness and abundance were related to both arrival vectors and environmental factors in northeast Pacific eelgrass. Using correlation tests and generalized linear models, we examined how nonnative macroinvertebrates (benthic, epifaunal, and large mobile) and some algae species were related to arrival vectors (shipping and aquaculture) and environmental factors (climate variables, human population density, and native richness and abundance). We found 12 nonnative species, 50 % with known negative impacts within eelgrass habitats. For benthic organisms, both nonnative richness and abundance were strongly correlated with shellfish aquaculture activities, and not with shipping activity. For epifaunal nonnative richness and abundance, neither vector was significantly correlated. Climate (temperature and salinity) helped explain nonnative richness but not abundance; there was no relationship of nonnative richness or abundance to native species richness and abundance or population density. Results suggest that aquaculture activities are responsible for many primary introductions of benthic nonnative species, and that temperature and salinity tolerances are responsible for post-introduction invasion success. While aquaculture and shipping vectors are becoming increasingly regulated to prevent further international spread of nonnative species, it will be important when managing nonnatives to consider secondary spread from intraregional transport through local shellfish aquaculture and shipping. 相似文献
3.
Takeshi Nose Dr. 《GeoJournal》1985,10(3):261-276
Conclusions During the last ten years, aquaculture, especially mariculture has undergone remarkable expansion to counter-balance the gap between the supply and demand of fishery products in Japan. Its expansion has also been supported by the traditional preference of the Japanese people for seafood. Mariculture is now being forced to change its structure due to adverse economic circumstances such as the rise in the cost of energy, feeds and other materials for culture, low market prices, deterioration of environmental conditions, and many other factors. Before these constraints can be resolved, advanced scientific knowledge and technologies must be integrated to develop new types of aquaculture. Expansion of maricultural activities to more open-sea and off shore areas would be one route to follow. Technologies for the development of formulated diets not only for young but also for adults and larvae, establishment of feeding standards, prevention of epizootic diseases must support the establishment of modern aquaculture.The culture-based fisheries, or marine ranching, is becoming a subject for further development in Japan. Much research work has been conducted with a great degree of governmental support. Establishment of a net work of seedstock production farms has made it possible to carry out releasing experiments on a large scale. A newly integrated restoration system could be developed on the basis of these experiments, even though the profits resulting from the artificial restoration of stocks is not thouroughly verified at present. The commencement of a national scheme for culture-based fisheries would be a manifestation of the enthusiasm of the Japanese fish industry. 相似文献
4.
J. Stephen Hopkins Paul A. Sandifer M. Richard DeVoe A. Frederick Holland Craig L. Browdy Alvin D. Stokes 《Estuaries and Coasts》1995,18(1):25-42
Shrimp culture technology has resulted in development of a major shrimp farming industry worldwide. Without the shrimp farming industry, increasing demands for shrimp by consumers could not be met, resulting in increased pressure on wild shrimp resources. Unfortunately, there are realized and potential adverse environmental effects on estuarine ecosystems as a result of shrimp farming. The effects can be categorized as wetland destruction for construction of shrimp farms, hypernutrification of estuarine ecosystems by shrim pond effluent, “biological pollution” of native shrimp stocks through escapement of aquaculture stocks, water use and entrainment of estuarine biota, and impacts of shrimp farm chemicals on estuarine systems. While the shrimp farming industry in the United States is small, the United States is effectively addressing all the realized and potential environmental impacts through regulation and research at the federal and state levels. Areas of regulation and research include stringent prohibitions on wetland destruction, regulation of effluents and support of research to eliminate and/or reduce effluents, escapement prevention technology and development of high-health stocks, minimizing entrainment of estuarine biota through water conservation and screening technology, and regulation of chemical use in the shrimp farming industry and support of research on shrimp pathology and environmentally safe disease control. Work is still in progress and not all problems have been resolved to the complete satisfaction of shrimp farmers and estuarine conservationists. However, the situation in the United States should serve as a model of how to encourage sustainable economic development through commercial shrimp farming while abating adverse environmental impacts on estuarine systems. To further improve the situation, the development and adoption of “best management practices” for shrimp aquaculture are recommended. 相似文献
5.
天然气:21世纪我国国民经济新的增长点 总被引：5，自引：0，他引：5
“天然气－21世纪的能源”已成为全人类的共识，新气田的不断发现，储量的不断增长和新的跨国输气管线的建成以及贸易范围的扩大加速了天然气工业的全球化和全球天然气化的进程，以煤为主的中国能源工业面对这难得的国际经济环境和国外已经充分开发利用的天然气技术系统以及国内日益高涨的需求呼声，审时夺势，顺应潮流，适时调整了能源战略，加大了天然气勘探力度，不断摸清了资源家底，使储量和产能大幅度增长，并陆续启动了基础设施建设项目，我国天然气孕育着大开发，大发展的喜人前景，可以预料，天然气工业将成为21世纪我国国民经济新的增长点。 相似文献
6.
First record of 1.2 Ga quartz dioritic magmatism in the Archaean Yilgarn Craton,Western Australia,and its significance 总被引：1，自引：0，他引：1
Y. Qiu N. J. McNaughton D. I. Groves J. M. Dunphy 《Australian Journal of Earth Sciences》2013,60(3):421-428
Farming of southern bluefin tuna in South Australia currently contributes to more than 30% of the value of the aquaculture production in Australia. This study investigated the natural sedimentary setting of the area designated for this important industry in coastal waters off Port Lincoln, and explored the links between the natural distribution of sediments and potential environmental effects and risks to the industry. Sediments were mostly composed of poorly sorted silts and fine sands, predominantly skeletal remains of carbonate-secreting organisms. The contribution of plankton to the organic matter remaining in the sediments was calculated to be in excess of 80% using concentration-dependent stable-isotope mixing models. An erosional area was identified south of Rabbit Island where sediments contained up to 50% siliciclastic material, grainsize distributions were better sorted and coarser, and organic carbon and total nitrogen contents were very low. In contrast, deeper waters north of Cape Donington were identified as a depocentre for fine sediments, which contained organic matter levels twice those elsewhere in the region despite the extremely high carbonate contents (>80%). The heavier stable isotopic signature of nitrogen suggested that this organic matter comprised a greater fraction of weathered components, probably advected to the area by suspended and bedload transport. This local variability of sediment characteristics in the farming zone suggests that the benthic assimilative capacity of farmed sites will depend on their location. Wastes from pens located south of Rabbit Island in particular are likely to be quickly winnowed out by wave and tidal action. These pens are also less likely to be affected by resuspension of fine sediments that might be associated with unusually severe storms. 相似文献
7.
A. Sinden S. C. Sinang 《International Journal of Environmental Science and Technology》2016,13(12):2855-2862
The presence of toxic cyanobacteria in aquaculture systems is a matter of concern due to its capability to produce toxin known as microcystin. This study was carried out to determine the presence, abundance and toxic potential of cyanobacteria in selected aquaculture systems in Perak, Malaysia, as well as to identify the potential main trigger of toxic cyanobacterial blooms in aquaculture water. In this study, a total of 40 freshwater fish ponds were sampled from 10 different aquaculture farms in Perak, Malaysia. Results revealed that the most frequently found cyanobacterial taxa in Perak aquaculture water was Microcystis spp., where it was detected in all of the studied ponds. During the sampling period, 75 % of the sampled ponds water contained unsafe levels of microcystin with concentrations up to 295.86 µg MC-LR equivalent L?1. This study also discovered that a combination of temperature and pH was the key environmental factor that triggered the proliferation and toxicity of cyanobacteria, whereby temperature was statistically proven to be a more powerful predictor in comparison with pH. This study has implied that cyanobacteria can present health risk to human through aquaculture fish consumption. Moreover, the risk posed by cyanobacteria in aquaculture systems will be amplified by the influence of global warming, with rising water temperatures up to 32 °C. 相似文献
8.
山东聊城东部地热田位于阳谷凸起的北部区内,区内常被开发利用的奥陶纪马家沟组热储层的地热流体主要为地热水,其矿化度和温度较高,水量较大,属氯化物·硫酸盐一钠·钙型和中性极硬型盐水;其锶、氟的含量达到了命名矿水浓度;偏硼酸的含量达到了有医疗价值浓度,有时会达到矿水浓度;偏硅酸的含量达到了矿水浓度;对金属具有强腐蚀性,对普通水泥具有结晶性侵蚀,对各类水泥无分解性侵蚀,并含有铁、锂、锰等多种对人体有益的微量元素。可以在地热供暖、洗浴、医疗保健、种植业、养殖业、工业等行业进行广泛地开发利用。 相似文献
9.
J. F. Muir Ph. D. 《GeoJournal》1985,10(3):277-298
The prosperous industrial areas of North America and Europe support a diverse and vigorous aquaculture industry. Although climatic restrictions of temperature, photosynthetic energy and exposure may limit the potential, the relatively intensive forms of production of the area are supported by good and expanding market demand. Thus, many forms of production are technically sophisticated. Capital and operating cost levels are generally high and technically difficult. Poorly marketable products are not economically viable. The bulk of production is therefore concentrated on three fish groups: rainbow trout, Atlantic and Pacific salmon, channel catfish, and two mollusc groups: oysters and mussels. The potential for growth and development of the industry is good but is increasingly controlled by market expansion rather than by technical innovation. 相似文献
10.
福建省霞浦县农业地球化学初步研究 总被引：1，自引：0，他引：1
在利用全省１：２０万区域化探水系沉积物测量成果基础上，结合重点地区的土壤调查，对霞浦县的农业地球化学环境进行了分区。并开展了荔枝、茶叶、油奈、剑蛏的地球化学研究，为扩种、移殖这些名、特、优品种及合理施肥提供科学依据，揭示了地球化学解决农业问题的特殊作用。 相似文献
11.
在工业生产过程中,CO2的大量排放被认为是导致气候变暖的重要因素之一,因此控制和减少CO2排放已成为人类社会面临的紧迫任务。水泥工业是人为排放CO2的重要来源之一,这就意味着水泥工业会在一种不断增加的管理压力下减少CO2的排放量,以应对全球变暖的现状。水泥生产过程中CO2的直接排放和间接排放两大排放途径,直接排放主要包括碳酸盐分解,烧成燃料/非烧成燃料的燃烧。间接排放主要是指电力消耗所产生的CO2。针对碳的排放环节,有效可行的CO2减排措施,例如原料、燃料的替代,熟料化学成分的改变,能源效率的提高等,对我国水泥工业的碳减排提出一些建议和看法。 相似文献
12.
吉林省中部是全国重要的商品粮基地和东北重要的经济区,水资源的短缺和不合理利用严重制约了该区社会经济的可持续发展。根据水资源时空分布特征和开发利用现状,认为本区总体上为水资源脆弱区。从水资源需求趋势和供给能力两方面,综合判断水资源利用高峰将出现在2020年左右,用水量约为55～60亿m~3。水资源利用结构将有显著的变化,到2030年时,居民用水、工业用水、农业用水三者需水量之比达到1∶2∶2的水平。提出建设节水农业是实现区域水资源可持续利用的战略性措施；合理利用雨洪资源是提高供水体系稳定性的关键手段；实施水源置换工程是改善供水系统的重要举措；建立合理的水价体系是实现水资源合理配置的基础性工程；加强水资源的综合管理是实现水资源可持续利用的体制保障。 相似文献
13.
Net-pen aquaculture results in the introduction of excess fish food and fecal matter in coastal waters. These wastes may modify the benthic environment. Mathematical models are developed in this study to simulate tidal and wind-driven currents, waves, and the resulting dispersion of fish food and fecal matter in coastal Maine, a region where limited modelling studies have been performed. Cobscook Bay and Toothacher Bay in Maine are studied in detail through the use of mathematical models and field data. We find that a systematic, site-specific, step-by-step modeling strategy involving the use of numerical models to simulate the overall hydrodynamic environment in combination with a waste-particle transport model can be an extremely powerful method of determining a priori whether aquaculture operations will cause high rates of net-pen waste accumulation at a particular site. 相似文献
14.
钛矿是我国对外依存度较高的矿种之一,对我国战略性新兴产业的发展起着重要的支撑作用,对全球钛矿行业的发展现状进行分析与研究,能够为我国钛矿资源安全提供重要研究依据.本文对全球钛资源的储量及分布状况、钛资源的生产和消费情况进行了分析.分析结果显示,我国是钛资源大国,钛储量位居世界第一;但多为共伴生矿,品位不高.钛精矿进口量呈逐年上升趋势,对外依存度超过了60％.受当今国际政治经济环境的影响,钛矿资源的国际贸易形势必然会受到影响.同时随着我国战略性新兴产业的发展,钛的消费需求将不断增加,因此,加大我国钛资源的勘查和资源储备,加快我国钛行业的产业升级转型以及保障钛矿的资源供给安全是未来整个行业的重要议题. 相似文献
15.
Sian E. Loveless John P. Bloomfield Robert S. Ward Alwyn J. Hart Ian R. Davey Melinda A. Lewis 《Hydrogeology Journal》2018,26(6):1975-1987
Shale gas is considered by many to have the potential to provide the UK with greater energy security, economic growth and jobs. However, development of a shale gas industry is highly contentious due to environmental concerns including the risk of groundwater pollution. Evidence suggests that the vertical separation between exploited shale units and aquifers is an important factor in the risk to groundwater from shale gas exploitation. A methodology is presented to assess the vertical separation between different pairs of aquifers and shales that are present across England and Wales. The application of the method is then demonstrated for two of these pairs—the Cretaceous Chalk Group aquifer and the Upper Jurassic Kimmeridge Clay Formation, and the Triassic sandstone aquifer and the Carboniferous Bowland Shale Formation. Challenges in defining what might be considered criteria for ‘safe separation’ between a shale gas formation and an overlying aquifer are discussed, in particular with respect to uncertainties in geological properties, aquifer extents and determination of socially acceptable risk levels. Modelled vertical separations suggest that the risk of aquifer contamination from shale exploration will vary greatly between shale–aquifer pairs and between regions and this will need to be considered carefully as part of the risk assessment and management for any shale gas development. 相似文献
16.
Jiří Blažek 《GeoJournal》1994,32(3):261-267
Far-reaching changes launched in 1989, aimed mainly at establishing a democratic society and market economy have clearly brought many positive results. However, there is also a negative side to these progressive changes both in economic and social spheres. There are many difficult tasks ahead such as the reestablishment of a democratic and economically effective local government which will be able to fulfil contemporary needs and requirements. The aim of this report is not to describe all the changes occurring in local government or to review different opinions about what should be done, but rather to concentrate on one of the most important issues facing this body of government, that of financial reform. Special attention will be given to the economic performance of municipalities with regard to their population size. It will be argued that data from local budgets can reveal important features about the performance of local and regional economies which cannot be obtained in any other way. 相似文献
17.
昆明滇池周围磷矿资源现状及开发前景 总被引：2，自引：0，他引：2
云南磷矿探明储量居全国首位,滇池周围保有储量占全省保有储量68.64%。磷化工与磷复肥基地和国内最大露采矿山,均在此区域内。"优矿低用"、矿山规模化小、国营矿山效益差,均是发展中要解决的问题。合理开采富矿、发展磷肥要"湿、热并举"、实施"矿电联营"、政府给予优惠政策,是云南磷矿业可持续发展的重要举措。 相似文献
18.
Quantitative models of sedimentary basin filling 总被引：1，自引：0，他引：1
Chris Paola 《Sedimentology》2000,47(Z1):121-178
Quantitative modelling of the filling of sedimentary basins was begun in earnest in the 1960s. Dozens of themes and variations have been proposed since then, and have yielded an abundance of idealized stratigraphic patterns as functions of both imposed changes and basin properties. Post‐plate‐tectonic modelling began with ‘rigid‐lid' models, which show the stratigraphic signature of subsidence variation. This work introduced the connection between stratigraphy and the rheology of the lithosphere. Rigid‐lid models are the simplest type of geometric model, in which the sediment surface is assigned prescribed geometries, usually corresponding to different depositional environments. These can reproduce many aspects of overall stratal geometry but are formally restricted to relatively long timescales, for which quasi‐steady surface topography can be assumed. So‐called dynamic models attempt to represent the morphodynamics of the sediment surface by abstracting and averaging short‐term transport processes. Most of the dynamic models proposed to date can be seen as special cases of a single general morpho‐dynamic equation. The most important result of the first wave of quantitative basin‐filling models is that even relatively simple models can produce reasonable stratal patterns. We now have a wide array of tools for exploring scenarios, searching for general behaviours and effects, and making initial quantitative predictions. We have also learned that basin response to external forcing as recorded in stratigraphy can be as sensitive to the characteristics of the basin as to the forcing. The main brake on the development of basin modelling is not computing power but lack of methods and data for testing the models we have already developed. Physical experiments, which are only just beginning, are one means of doing this. Experimental stratigraphy is a bridge to quantitative field tests, which will require collaboration among academic researchers from a wide range of areas, and between academia and industry, on projects of greater scale and degree of integration than we have seen so far. The advancement of quantitative sedimentary geology will also require significant changes in the way the subject is taught, at all levels. 相似文献
19.
市场经济给中国的建筑业带来了高度繁荣，建筑师在对中国建筑业现状欢欣鼓舞的同时，也遇到了种种困惑。本文谈谈建筑师实际中所面临的一些问题，希望能引起建筑界同仁及全社会的注意；也期望着建筑界这些不规范的运作时期早日成为历史！ 相似文献
20.
锗的地球化学及资源储备展望 总被引：5，自引：2，他引：3
锗是众多高新技术领域的重要原材料,随着无人驾驶、5G、太阳能电池和催化剂等产业的飞速发展,锗在中国及全球未来需求量将十分巨大,在国民经济建设中具有重要地位,许多国家将其作为国家重要战略资源进行严格控制、管理和储备,因此,锗资源的地质勘探和战略储备是今后国家持续发展的重要需要。文章总结了锗的地球化学性质、晶体化学及矿物学、地球化学行为控制因素、全球富锗矿床类型等,根据我国锗资源特征,结合"川滇黔铅锌矿集区"内多数矿床中锗超常富集普遍现象,提出该区可作为中国锗资源战略储备基地,具有巨大潜在经济价值。开展"川滇黔铅锌矿集区"锗超常富集机理研究,不仅可以补充和完善锗地球化学行为的科学内容,提供认识该区铅锌成矿作用的重要地球化学信息,更重要的是为地质勘探的深入和综合利用该区锗资源提供科学依据,从而为建立中国锗资源战略储备基地提供实际地质地球化学支撑。虽然中国是全球最大的锗生产国和出口国,但其产品多为初级产品,加强锗产品深加工研发不仅具有广阔的前景,也将是中国锗资源综合利用发展趋势。 相似文献