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新疆天山北坡气候变化的生态响应研究 总被引：8，自引：2，他引：8
通过近40年天山北坡气候、水文、现代冰川、湖泊观测数据和近10年卫星遥感数据, 利用遥感和GIS技术, 从地表覆被生态系统和景观尺度, 提出了一套基于遥感的干旱区生态自然变化信息提取的研究方法, 分析了近40年天山北坡气候的变化趋势和与之相应的生态响应关系. 结果表明: (1) 近40年天山北坡气候变化的总体趋势是气温和降水增加, 特别是20世纪90年代以来的近10年气温、降水与径流量增加幅度较大; (2) 近10年天山北坡各地理分区植被综合指数显著提高, 提高幅度较大的是人工绿洲区和前山带, 其变化趋势有利于植被生态的改善; (3) 干旱区植被生态对气候变化的响应非常敏感, 由于近10年天山北坡气候的变化, 其植被覆盖度和生物量持续增加, 平原区增幅明显大于山区, 后期增幅明显大于前期. 相似文献
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青藏高原东北部树木年轮记录揭示的最高最低温的非对称变化 总被引：1，自引：0，他引：1
江河源区自然环境严酷, 生态系统脆弱. 近年来由于该区域日趋严重的生态环境问题使之逐渐成为全社会所广泛关注的焦点地区. 根据采自青藏高原东北部黄河源区西顷山和阿尼玛卿山的祁连园柏树轮样芯, 重建了研究区过去近425 a来冬半年的最低温和近700 a来夏半年最高温. 1578~1940年的近400 a间研究区冬半年最低温度的波动较为平缓, 但是自1941年来以来有急剧的升温趋势. 夏半年最高温在20世纪末表现出明显的升温趋势. 近425 a来最高温和最低温的变化存在非对称现象. 最高温和最低温在近425 a来的变化非常相似, 但最低温的变化比最高温的变化超前大约25 a左右. 如果在未来30 a内最高温和最低温的变化保持过去近425 a来的相关趋势, 那么在未来30 a内, 最高温也将继续剧烈升温. 相似文献
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京津冀城市群地区城镇化与生态环境近远程耦合能值代谢效率及环境压力分析 总被引：1，自引：0，他引：1
《中国科学:地球科学》2017,(7)
在解析城市群地区城镇化与生态环境之间近远程耦合关系的基础上,借助城市能值代谢方法,分析了1980~2014年近35年京津冀城市群地区城镇化与生态环境近远程耦合代谢效率及环境压力.结果表明:(1)近35年来京津冀城市群地区总代谢能值呈上升趋势,经历了由近程要素主导向远程要素主导的转变过程,远程要素代谢能值总量占总代谢能值的比重由1980年的30.87%上升到2014年的67.43%,能值外向度不断提高,城市群发展对远程要素的依赖程度越来越大.(2)近35年来京津冀城市群近远程要素能值代谢强度加速下降,由1980年的1.15×10~(21)Sej/亿元下降到2014年9.69×10~(19)Sej/亿元,体现出京津冀城市群经济效率不断提高;相应地人均能值量由1980年的7.8×10~(15)Sej/人增加到2014年5.83×10~(16)Sej/人,反映了京津冀城市群地区社会福利水平逐步提高.(3)近35年来京津冀城市群地区近远程要素能值代谢的环境负荷率不断提升,环境压力不断增大.近程要素能值代谢的环境负荷率由1980年的8.30上升到2014年的43.46,同期远程要素能值代谢的环境负荷率由4.15上升到92.03.本文定量解决了京津冀城市群发展对远程要素依赖程度和远程要素输入对城市群造成的环境负荷压力问题,提出的研究结论为京津冀城市群地区有效控制外来人口增长、逐步疏解北京非首都功能、优化调整经济结构、提高经济运行效率、治理环境污染和推进京津冀协同发展等提供了定量的决策参考依据. 相似文献
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太湖流域典型中小型湖泊富营养化演变分析(1991-2010年) 总被引：4，自引：3，他引：1
通过分析太湖流域的中小型湖泊富营养化指标近20年的变化趋势,探讨流域富营养化特征的总体演变趋势.从全流域看,总氮浓度在近20年里呈稳中略降的趋势;而总磷浓度在近20年里有较明显上升趋势;作为营养物上升的直接响应指标叶绿素a呈快速上升趋势,平均值从1991年的7.0μg/L上升至2010年的27.5μg/L,20年间上升了近3倍,叶绿素a数据离散程度出现大幅上升,标准差从1991年的1.25μg/L上升至2010年的19.06μg/L,说明各湖富营养化程度的空间分异性在加大,藻华风险增加;透明度在近20年中虽有波动,但整体仍呈下降趋势.综合营养状态指数(TLIc)计算结果显示,近20年过水型湖泊淀山湖和昆承湖的TLIc指数明显高于封闭型湖泊水源地尚湖和傀儡湖.典型过水型湖泊(淀山湖)、封闭型湖泊水源地(尚湖和傀儡湖)以及典型的渔业生产型湖泊(长荡湖)的富营养化演变过程有所差异,主要受湖泊本身自然属性、污染控制强度、管理模式、功能定位等影响. 相似文献
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华安汰内水氡井近震映震能力分析 总被引：2，自引：2，他引：0
通过对华安汰内观测井1987年以来的氡值资料及近震映震能力的分析,发现震前明显突跳异常的近震震中近北西向展布在福安—南靖断裂两侧,结合区域地质构造背景,探讨了这种现象发生的原因。 相似文献
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J—B表自1904年问世以来已几十年了。它主要依据欧州,日本和北美的地震资料获得。其中近震走时表目前仍用于四川区域台网近震定位。四川地区处于青藏高原边缘地带,地壳速度模型与J—B近震表采用的模型有明显的差别,用J—B表定位有时误差很大。另一方面,J—B表本身也存在误差。 相似文献
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本文回顾了1959年中国近震震级标度公式建立以来近震震级研究的进展。在调查分析全国三十余个地方台网(包括传输台网)M_L震级测定现状的基础上,围绕着中国近震震级的统一和标准化,较系统地论述了区域量规函数、台站校正、测定值离散度和误差、仪器影响以及测定近震震级的其他方法、中国近震震级和Richter原始M_L震级的关系等主要问题。 相似文献
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近震震级 总被引：1，自引：0，他引：1
葛焕称 《地震地磁观测与研究》1982,(3)
近(near)震震级或地方性震级,也有称区域性(regional)地震震级。一般指震中距2000Km以内的地震而言。由于地区性结构的差别,近震震级不能像远震震级那样建立全球性的统一标度。1935年Richter在南加利福尼亚引入的近震震级标度M_L,作为原始的震级标度。世界其它地区再根据本区域的特征建立本区域的近震震级标度,这种标度必须通过某种 相似文献
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《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
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Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
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K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献