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1.
A multi-scale study on land use and land cover quality change: The case of the Yellow River Delta in China 总被引:5,自引:0,他引:5
This paper presents a case study of the Yellow River Delta in China, to trace land use and land cover changes during the past
20 years, with an emphasis on land quality changes. Three sets of data are used in this case study: remote sensing data derived
from satellite images; crop yield data from statistics; and soil data collected by the researchers in the field. Our study
reveals that at the regional scale, LUCC has taken place in a positive direction: vegetation cover has been expanding and
crop yields per hectare have been on rise. However, while the overall eco-environment has improved, the improvement is uneven
across the Delta region. At local levels, some areas show signs of increased salinization and declining organic content. Both
natural forces and human activities are responsible for the LUCC, but human activities play a more important role. While some
impacts of human activities are positive, the damages are often long-lasting and irreversible. We also conclude that it is
necessary to use both macro data (such as remote sensing data) and micro data (data collected in the field) to study land
quality change. The former are efficient in examining land quality changes at the regional scale, the latter can serve to
verify ground patterns revealed from macro data and help to identify local variations, so as to get a comprehensive understanding
of LUCC and promote sustainable land use and land management.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
3.
YIN Qunjian ZHANG Weijia LI Xuegong ZHOU Lihong QI Xiaoqing ZHANG Chan WU Long-Fei 《海洋湖沼学报(英文)》2019,(1):210-222
Trimethylamine N-oxide(TMAO) is widely dispersed in marine environments and plays an important role in the biogeochemical cycle of nitrogen. Diverse marine bacteria utilize TMAO as carbon and nitrogen sources or as electron acceptor in anaerobic respiration. Alteration of respiratory component according to the pressure is a common trait of deep-sea bacteria. Deep-sea bacteria from dif ferent genera harbor high hydrostatic pressure(HHP) inducible TMAO reductases that are assumed to be constitutively expressed in the deep-sea piezosphere and facilitating quick reaction to TMAO released from ?sh which is a potential nutrient for bacterial growth. However, whether deep-sea bacteria universally employ this strategy remains unknown. In this study, 237 bacterial strains affliated to 23 genera of Proteobacteria,Bacteroidetes, Firmicutes and Actinobacteria were isolated from seawater, sediment or amphipods collected at dif ferent depths. The pressure tolerance and the utilization of TMAO were examined in 74 strains. The results demonstrated no apparent correlation between the depth where the bacteria inhabit and their pressure tolerance, regarding to our samples. Several deep-sea strains from the genera of Alteromonas, Halomonas,Marinobacter, Photobacterium, and Vibrio showed capacity of TMAO utilization, but none of the isolated Acinebacter, Bacillus, Brevundimonas, Muricauda, Novosphingobium, Rheinheimera, Sphingobium and Stenotrophomonas did, indicating the utilization of TMAO is a species-speci?c feature. Furthermore, we noticed that the ability of TMAO utilization varied among strains of the same species. TMAO has greater impact on the growth of deep-sea isolates of Vibrio neocaledonicus than shallow-water isolates. Taken together, the results describe for the ?rst time the TMAO utilization in deep-sea bacterial strains, and expand our understanding of the physiological characteristic of marine bacteria. 相似文献
4.
环渤海海岸带是人-地相互作用的强烈地区,土地利用是人-地作用的重要方式,并通过格局变化体现。文章利用2000年和2010年中国土地利用现状遥感监测数据,利用GIS软件平台,对环渤海海岸带及所属的38个县区土地利用变化进行了省际和距海缓冲区分析。结果表明:(1)地类面积在省(市)际间分布不均衡,其中林地集中分布在辽宁省,草地集中分布在山东省,河北省城镇工矿建设用地、天津市水域和城镇工矿建设用地比重大,耕地在三省一市分布较均衡,且为区域基质地类;(2)地类面积按照距离海岸线由近到远的次序,分布有差异。其中城市建设用地集中分布在距海岸线15 km区域内,林地占比随离海岸线距离增加逐渐提高,未利用地和水域占比逐渐降低,其他地类无明显变化;(3)从地类转移情况看,在2000—2010年期间,地类呈现由草地—耕地—建设用地的转移路径;其中在15 km范围内,水域和耕地成为建设用地的主要转入源;在其他范围转入源以耕地为主;(4)从空间热点上看,渤海湾的天津地区是建设用地增加热点地区,而莱州湾西部是耕地增加热点地区;(5)环渤海海岸线不断向海洋延伸,其中渤海湾延伸最大,其次为莱州湾东南部和辽东湾的东岸。 相似文献
5.
研究分析了静海地磁台2002~2006年观测资料的加卸载响应比异常与邻区ML 4.0以上地震之间的关系,提出了适用于静海地磁台的地震分析预报异常形态特征和阈值判据. 相似文献
6.
ASP应用中COM组件开发方法研究 总被引:2,自引:0,他引:2
从ASP技术与COM技术出发,针对MCU远程控制应用的多层分布体系结构特点及应用要求,详细论述了如何进行组件线程类型选择、接口设计、物理定位开发与实现具有特定功能的COM组件并如何在ASP应用中创建和扫行,以实现远程控制MCU功能。论述了在设计与实现COM组件过程中,其安全性与作用域的选择。 相似文献
7.
Despite a recent increase in the number of vulnerability analyses there has been relatively little discussion of vulnerability
assessment of social–environment system, especially when they face multiple hazards. In this study, we developed an applicable
and convenient method to assess vulnerability of social–environment system at a regional scale. Vulnerability is quantified
by measuring three critical elements (i.e. hazards, sensitivity, and resilience) through some key variables. The results showed
that vulnerability is high in Miaofeng Mountain in Mengtougou District, the hills of Pinggu County and the riparian zones
of the lower courses of the Beiyun and Yongding Rivers; but low in the city of Beijing and the southwestern part of the Fangshan
District. Areas of very high, high, medium, and low-vulnerability account for 6.19, 25.48, 33.06, and 35.27% of the total
area, respectively. The degree of vulnerability decreases in a northwest direction in mountainous areas and declines from
watercourses to riparian zones along a lateral direction in the plain. Some adaptive strategies are also proposed. 相似文献
8.
Natural and anthropogenic factors in coastal wetland changes are widely discussed in wetland studies. Previous literatures have demonstrated that many factors may cause wetland change and argued that the global climate change and nutrient enrichment may become the most important ones in the next 50 years. Through field investigation, with the help of remote sensing technology and geographic information system, this research discusses the wetland change in Tianjin under the great pressure of rapid economic development, population growth, and sea-level rising. These findings include: (1) the wetland area expanded from 466.50 km2 to 658.38 km2 between 1987 and 1998, but it shrank to 550.5 km2 by the year of 2006. (2) The results show that the groundwater has not been contaminated while the surface water has been polluted. (3) The questionnaire survey shows that the social environment in some specific ways impedes the protection of natural reserve. In order to achieve the harmony between human and nature, feasible countermeasures on how to keep ecological balance should be immediately taken. Consequently, natural conservation and sustainable economic development will be realized. 相似文献
9.
黄河三角洲农牧业生产潜力 总被引:6,自引:0,他引:6
本文从对黄河三角洲的宜农地和宜牧地的分析入手,对该区农作物生产潜力、牧草及载畜量潜力进行了探讨。并针对目前农牧业生产水平和存在的问题,提出了相应的对策。 相似文献
10.
在初步明确东亚沙尘气溶胶对流层-平流层输送监测事实的基础上,利用观测资料、NCEP再分析资料以及基于中尺度天气模式MM5的数值模拟方法,对一次蒙古气旋沙尘暴过程中沙尘对流层-平流层输送问题进行了初步分析.结果表明:斜压不稳定是本次蒙古气旋发展的主要强迫要素,伴随气旋发展成熟,高空切断低涡的形成引导高空急流下落并诱发对流层顶折叠和高空位涡下传.对流层顶折叠区呈漏斗状,底部达500 hPa左右.高空急流产生近似垂直的下落,并在高空切断低涡的南侧和东侧达到最强.在对流层顶折叠区周边的300-500 hPa,上升气流与低涡区偏西、偏南、偏东气流叠加,或水平横穿折叠的对流层顶,或斜升并准垂直地穿过下落的对流层顶到达平流层,且随时间的推移,空气质点能够进一步抵达平流层中部(100 hPa).轨迹分析表明,沙尘天气区对流层低层的空气质点在气旋涡旋上升气流的驱动下呈气旋式盘旋上升,并在对流层高层形成分支,一支穿过对流层顶到达平流层,并在平流层向下游进行反气旋式螺旋运动,另一支则留在对流层高层并向下游进行准水平的气旋式螺旋运动.在高空位涡下传过程中,主要产生平流层到对流层的净输送;高空位涡停止下传之后则出现对流层到平流层的净输送,且强度随时间呈指数型增长.这一特征有利于形成更强的沙尘对流层平流层输送. 相似文献