Large-scale impacts of bottom trawling on shelf primary productivity     

Costas Dounas  Ian Davies  George Triantafyllou  Panayota Koulouri  George Petihakis  Christos Arvanitidis  George Sourlatzis  Anastasios Eleftheriou 《Continental Shelf Research》2007

Disturbance of the seabed resulting from bottom trawling affects ecosystem processes, such as the rate and magnitude of nutrient regeneration. The potential responses of the plankton community arising from such effects can be modelled, provided that reliable data on the effects on nutrient fluxes are available. In a north Cretan outer continental shelf and upper slope fishing ground (Heraklion Bay, Crete, Eastern Mediterranean) we applied a new field instrument which can simulate the passage of trawl groundropes across the sea floor and made direct seasonal measurements of the rate of dissolved and particulate nutrient releases resulting from seabed disturbance. These observational data were then integrated in a 3D ecosystem model. Results revealed that bottom trawling may trigger off considerable productivity pulses, in addition to pulses from the natural seasonal cycle.  相似文献   

生态区评价研究的兴起与发展——以美国森林生态系统管理评价(FEMAT)研究为例   总被引：4，自引：0，他引：4       下载免费PDF全文

康慕谊  江源 《第四纪研究》2001,21(4):337-344

生态区评价是近年来出现在美国的一种新型区域生态系统管理方法的理论与实践科学研究,起始于美国总统森林会议(1993)后成立的森林生态系统管理评价组(FEMAT),目标是实现地区生态系统的科学管理.本文评介了生态区评价首项案例--美国西北太平洋沿岸区原始森林及其他各类森林经营管理方案的生态、经济、社会影响综合评价的科学与方法实践意义.指出FEMAT的生态区评价:1)迈出了生态区评价历史上坚实的第一步,实现了区域土地利用规划与生态系统管理方案从以行政疆域为准划分向以生态区域为准划定边界的转变;2)方案优化过程充分考虑区域生态、经济、社会的历史、现状与未来趋势等各方面,将科学、政策、管理融为一体,使之易于在实践中贯彻;3)促进了不同政府机构和利益团体间为实现资源开发与生态保育双重目标而共同协作.  相似文献   

环境与健康的评估问题和空间分析   总被引：1，自引：0，他引：1  

林绍颜 《地理学报》2001,56(2):239-247

评估环境污染对人民健康影响的研究需要结合空间，时间和统计分析，并吸引不同学科背景的研究人员合作研究，可是，在这个研究领域内，最重要的问题是研究结论的不可靠性程度很高，不同的研究方法会导致不同的结论，一个有系统的研究架构拥有不同的空间分析方法将会减少结论的可疑程度，有效的环保政策是需要可靠的研究成果，文中首先介绍在环境与健康的评估研究领域的四大重要问题，指出这项研究需要这项研究需要空间分析和地理信息系统方法，从而提出一个空间分析的研究框架和内裹的方法，通过路易斯安纳州的一个污染地点和肿瘤发病率关系研究实例，指出这项研究领域的各种问题和空间分析架构的重要性。  相似文献   

大连湾60多年来生态环境地质演化   总被引：5，自引：1，他引：5  

林景星  张静等 《地质学报》2001,75(4):527-536

依据对大连湾60多年来沉积柱的生态环境地质演化研究，发现其污染变化可以分为3个时期：①1933－1974年为洁净时段；②1974－1989年为污染较重时段；③1989－1997年为严重污染时段。若视第一时段的污染度为0，则第二时段的污染度为第一时段的8倍，第三时段的污染度为第一时段的25倍，可见污染度增加是非常迅速和严重的。其中Cd、Pb、As、S、Zn5种元素含量增加最快。1997年大连湾表面沉积物中Cd、Hg、Pb、As的含量分别为自然背景值的81．42倍、6．0倍、7．54倍、3．82倍，表明大连湾污染的严重性。研究发现自1950年以来大连湾生物多样性急剧下降，说明污染度增加已对生命健康造成严惩的影响。大连湾的臭水套已成为一个生物多样性异常低下的、超级污染的环境，是一颗巨大的隐性化学定时炸弹。  相似文献   

Evolution of accelerographs, data processing, strong motion arrays and amplitude and spatial resolution in recording strong earthquake motion   总被引：1，自引：0，他引：1  

M. D. Trifunac  M. I. Todorovska 《Soil Dynamics and Earthquake Engineering》2001,21(6)

This paper presents a review of the advances in strong motion recording since the early 1930s, based mostly on the experiences in the United States. A particular emphasis is placed on the amplitude and spatial resolution of recording, which both must be ‘adequate’ to capture the nature of strong earthquake ground motion and response of structures. The first strong motion accelerographs had optical recording system, dynamic range of about 50 dB and useful life longer than 30 years. Digital strong motion accelerographs started to become available in the late 1970s. Their dynamic range has been increasing progressively, and at present is about 135 dB. Most models have had useful life shorter than 5–10 years. One benefit from a high dynamic range is early trigger and anticipated ability to compute permanent displacements. Another benefit is higher sensitivity and hence a possibility to record smaller amplitude motions (aftershocks, smaller local earthquakes and distant large earthquakes), which would augment significantly the strong motion databases. The present trend of upgrading existing and adding new stations with high dynamic range accelerographs has lead to deployment of relatively small number of new stations (the new high dynamic range digital instruments are 2–3 times more expensive than the old analog instruments or new digital instruments with dynamic range of 60 dB or less). Consequently, the spatial resolution of recording, both of ground motion and structural response, has increased only slowly during the past 20 years, by at most a factor of two. A major (and necessary) future increase in the spatial resolution of recording will require orders of magnitude larger funding, for purchase of new instruments, their maintenance, and for data retrieval, processing, management and dissemination. This will become possible only with an order of magnitude cheaper and ‘maintenance-free’ strong motion accelerographs. In view of the rapid growth of computer technology this does not seem to be (and should not be) out of our reach.  相似文献   

Exploring the links between health and housing: The limitations of population health surveys     

Mark W. Rosenberg  Kathleen Wilson 《GeoJournal》2001,53(2):109-116

While it is intuitively attractive to link health status and the quality of housing, it is methodologically complex to identify the relative importance of housing because individual characteristics and environmental variables act as confounders. A secondary issue is that the data sets which contain detailed data on health status and environmental variables often contain only limited data on housing. Similarly, housing surveys rarely contain detailed data on health and environmental variables. Respondents from Montreal, Toronto and Vancouver in the public use micro-data files of the 1996/97 cycle of the National Population Health Survey make up the data sets for a series of logistic regression models where health status, allergies, asthma, arthritis, migraines and bronchitis/emphysema act as the dependent variables. Sets of variables which measure housing, the environment (smoking and alcohol consumption) and the socio-economic status of individuals are used as independent variables. The issues of confounders and the limitations of the data are illustrated by the results of the analysis. If we are to go beyond local area surveys and carry out broader analyses of the links between health status and the quality of housing, researchers and data collection agencies will need to re-think the artificial divisions between these two critical aspects of peoples' lives.  相似文献   

地下水中钼的含量及其与人群健康的关系   总被引：1，自引：0，他引：1  

曾昭华  曾雪萍 《四川地质学报》1995,(4)

本文以丰富的实际资料，论证了地下水中微量元素钼形成的主要控制因素及其与人群健康的关系。  相似文献   

地下管网健康档案管理平台的设计与实现     

刘旭 《北京测绘》2020,(5):610-613

针对地下管网隐患数据管理的应用需求,本文基于三维平台设计实现了地下管网健康档案管理平台,在三维场景加载地上精细模型和地下管网数据,以三维可视化的手段对管网各类隐患问题进行信息管理,结合二维GIS操作,实现了净距分析、覆土分析、占压分析等管线隐患分析功能,通过本平台建立的地下管网健康档案数据库,方便用户对各类管网隐患数据进行信息管理和统计,为管道病害修复、管网改造提升提供数据支撑,保证地下管网的安全运行。  相似文献   

Remote structural health monitoring with serially multiplexed fiber optic acoustic emission sensors     

陈仲裕  梁玉进  Farhad Ansari 《地震工程与工程振动(英文版)》2003,2(1):141-146

Development and testing of a serially multiplexed fiber optic sensor system is described. The sensor differs from conventional fiber optic acoustic systems, as it is capable of sensing AE emissions at several points along the length of a single fiber. Multiplexing provides for single channel detection of cracks and their locations in large structural systems. An algorithm was developed for signal recognition and tagging of the AE waveforms for detection of crack locations. Laboratory experiments on plain concrete beams and post-tensioned FRP tendons were performed to evaluate the crack detection capability of the sensor system. The acoustic emission sensor was able to detect initiation, growth and location of the cracks in concrete as well as in the FRP tendons. The AE system is potentially suitable for applications involving health monitoring of structures following an earthquake Supported by: National Science Foundation, Grant number CMS-9900338  相似文献   

Coral reef health and effects of socio-economic factors in Fiji and Cook Islands     

Hoffmann TC 《Marine pollution bulletin》2002,44(11):1281-1293

This research focuses on coral reef health in the South Pacific region, an area of high global coral diversity. Coral reef health surrounding four island case studies in the Cook Islands and Fiji have been assessed in areas that have not been previously surveyed. This study compares four islands with barrier and fringing reefs that have different levels of economic development, population pressure, land-use practices, and marine management practices. This interdisciplinary research methodology includes both ecological and social data collection to further understanding of human environment interactions. In comparing the reefs with different socio-economic factors, this research shows that reefs with traditional systems of resources management are healthier, population pressure is not the main factor causing the demise of the reefs and agro-industry is the main industry causing the degradation of the reef in these four South Pacific Islands. In addition, researchers need to use a whole reef perspective to examine coral reef health.  相似文献