The response of lake-glacier variations to climate change in Nam Co Catchment, central Tibetan Plateau, during 1970–2000     

WU Yanhong  ZHU Liping 《地理学报》2008,18(2):177-189

Based upon the 1970 aero-photo topographic map, and TM/ETM satellite images taken in 1991 and 2000, the authors artificially interpreted boundaries of lake and glaciers in Nam Co Catchment, and quantified lake-glacier area variations in different stages by “inte-grated method” with the support of GIS. Results show that from 1970 to 2000, lake area in-creased from 1942.34 km2 to 1979.79 km2 at a rate of 1.27 km2/a, while glacier area de-creased from 167.62 km2 to 141.88 km2 at a rate of 0.86 km2/a. The increasing rate of lake in 1991–2000 was 1.76 km2/a that was faster than 1.03 km2/a in 1970–1991, while in the same period of time, the shrinking rates of glaciers were 0.97 km2/a and 0.80 km2/a respectively. Important factors, relevant to lake and glacier response to the climate, such as air tempera-ture, precipitation, potential evapotranspiration and their values in warm and cold seasons, were discussed. The result suggests that temperature increasing is the main reason for the accelerated melting of glaciers. Lake expansion is mainly induced by the increase of the gla-cier melting water, increase of precipitation and obvious decrease of potential evapotranspi-ration. Precipitation, evaporation and their linkages with lake enlargement on regional scale need to be thoroughly studied under the background of global warming and glacier retreating.  相似文献   

Detection and temporal variation of Co in the digestive glands of the common octopus, Octopus vulgaris, in the East China Sea     

Takami Morita  Shigeyoshi Otosaka  Kou Nishiuchi  Haruya Yamada  Masayuki Minakawa 《Marine pollution bulletin》2010,60(8):1193-1199

⁶⁰Co were detected in common octopus specimens collected in the East China Sea in 1996-2005. The source of ⁶⁰Co has remained unclear yet. Stable isotope analyses showed that there was no difference in stable Co concentrations between octopus samples with ⁶⁰Co and without ⁶⁰Co. This result showed that the stable Co in the digestive gland of octopus potentially did not include a trace amount of ⁶⁰Co and the source of ⁶⁰Co existed independently. Furthermore, investigations of octopus in other area and other species indicated that the origin of the source of ⁶⁰Co occurred locally in the restricted area in the East China Sea and not in the coastal area of Japan. Concentrations of ⁶⁰Co have annually decreased with shorter half-life than the physical half-life. This decrease tendency suggests that the sources of ⁶⁰Co were identical and were temporary dumped into the East China Sea as a solid waste.  相似文献   

1975-2008 年西藏色林错湖面变化对气候变化的响应   总被引：10，自引：1，他引：9  

边多  边巴次仁  拉巴  王彩云  陈涛 《地理学报》2010,65(3):313-319

根据1975 年地形图、80 年代至2008 年的TM、CBERS 卫星遥感资料和近34 年(1975-2008 年) 的气温、降水量、蒸发量、最大冻土深度等气候资料分析得出,西藏那曲地区西部的色林错及其周围的错鄂、雅根错的面积在近30 年来呈较显著的扩大趋势,到2008 年面积分别为2196.23 km2、279.24 km²、103.07 km²,与1975 年分别增长了574.46 km²、11.59 km2和68.13 km²,增长速度分别为35.4%、4.3%和195%。色林错从1999-2008 年湖面扩大速度为20%,平均上涨了420 km²/10a,已超过纳木错面积,成为西藏第一大咸水湖。冰雪融水量的增加是湖泊上涨的根本原因,其次与降水量的增加和蒸发量的减少、冻土退化等暖湿化的气候变化存在很大关系。  相似文献   

8.4 ka以来纳木错湖芯介形类组合的环境变化意义     

谢曼平  朱立平  彭萍  王君波  汪勇  SCHWALB Antje 《地理学报(英文版)》2009,19(4):387-402

A 332-cm long lacustrine core was drilled in the Nam Co in the central-southern part of the Tibetan Plateau. From the core, 15 species of ostracods (Crustacea: Ostracoda), which belong to 6 genera have been identified. According to the variations of the ostracod assem-blages and the ostracods ecological features, which are sensitive to the changing environ-ment, three main stages can be distinguished as follows: Stage I was from 8400 to 6800 a BP, during which the climate was cold-humid, and the lake depth changed from shallow to deep. Stage II was from 6400 to 2500 a BP, during which the climate changed from warm-humid to cold-humid, and then to cold-dry. The lake depth gradually became deep. The shifting of cli-mate, from wet-cold to dry-cold during this period, had constructed the basis of present en-vironment in the Nam Co. Stage III was from 2500 a BP to the present, which showed a trait of lake depth increasing. At the earlier period of this stage, the climate kept as cold-dry as that in the former stage, but the salinity of the lake increased. At the later period of this stage, the degree of cold-dry was enhanced, and the activities of land surface runoff tended to be weakened. Our research also found that the peak values of ostracods with black shell was coherent with the maximum production of the ostracods, and agreed with the increasing sedimentary water dynamics. This indicated that the ostracods with black shell was simulta-neous with the high prolificacy of ostracod, and transported from other places. The abun-dance of Candona juvenile shells reflected the high mortality of that kind of ostracods under an unfavorable condition. This was probably a result of the rapid change of water dynamics of sedimentary environment.  相似文献   

Water Quality of the River Yamuna in the Delhi Stretch: Key Determinants and Management Issues   总被引：1，自引：0，他引：1  

Chaman Trisal  Tanveera Tabassum  Ritesh Kumar 《洁净——土壤、空气、水》2008,36(3):306-314

The assessment of water quality of the River Yamuna in the Delhi stretch was carried out by determining changes in the concentration levels of 19 physico‐chemical parameters. It was observed that vegetation plays an important role in acting as a biological sink for mineral nutrients, thereby restoring the water quality. It is proposed that restoration of the inundation pattern of floodplains would greatly help in re‐aeration of the overlying water and re‐absorption of pollutants through mud/water exchanges.  相似文献   

都市农业加工型企业的发展机理与模式     

杨振山  蔡建明 《地理研究》2007,26(2):363-372

都市农业是城市化进程中崭新的农业形态,但缺乏对其组织形式和生产方式的实证研究。本文基于对互润(国际)食品集团的调查实例,详细分析了都市农业加工型企业的成长机理,指出制度平台、政府行为和社区沟通是企业发展的外层机理,是企业平稳运行的基础;生产经营活动及其不断的扩张构成了企业发展的内层机理;创新和企业管理及市场的内、外部控制所形成的内核机理是企业发展的核心动力。据此,文章总结了都市农业加工型企业的发展模式,并就都市农业加工型企业如何发展提出了建议。  相似文献   

西藏纳木错晚更新世以来湖面变化和湖相沉积中粘土矿物显示的环境信息   总被引：13，自引：1，他引：12  

朱大岗  孟宪刚  赵希涛  邵兆刚  马志邦  杨朝斌  王建平  吴中海 《地质力学学报》2004,10(4):300-309

通过对西藏海拔最高、面积最大湖泊-纳木错周缘湖相沉积、湖岸堤的野外调查和湖岸阶地的水准测量,发现在纳木错沿岸拔湖48m以下,发育有6级湖岸阶地,拔湖48~139.2m发育有高位湖相沉积。湖相沉积物的同位素测年结果表明,纳木错湖泊发育与藏北高原东南部古大湖演化可划分为3个阶段:①116~37kaB.P.间的古大湖期;②37~30kaB.P.间的外流湖期;③30kaB.P.以来的纳木错期。根据纳木错晚更新世以来湖相沉积中粘土矿物的X光衍射分析结果,以及采用比值法、高岭石法和衍射峰法的研究,探讨了粘土矿物所显示的环境变化信息。粘土矿物成分变化表明,该区已具备了寒温带干旱、半干旱区的气候环境特征。为研究青藏高原的湖泊演化、气候变化、古地理变迁及其隆升过程等提供了新资料。   相似文献   

西藏玛旁雍错和拉昂错水深、水质特征及现代沉积速率   总被引：4，自引：2，他引：2  

王君波  彭萍  马庆峰  朱立平 《湖泊科学》2013,25(4):609-616

基于2009年和2010年分别在玛旁雍错和拉昂错开展的2次野外湖泊调查,本文简要报道这2个藏南内流水系湖泊的水深分布、湖水理化特征及湖泊现代沉积速率.测深结果显示玛旁雍错湖盆形状规则,深水区坡度平缓,最大水深为72.6 m;拉昂错北部为较浅的河流冲积扇,通过狭长的水道与开阔的南部湖区相连,南部湖区中心平坦,实测最深处49.03 m;根据水深数据计算的玛旁雍错和拉昂错水量分别为1.462×10¹⁰m³和5.711×10⁹m³.玛旁雍错湖水剖面水质在垂直方向上呈现明显的分层结构,温跃层介于25~35 m之间,温度梯度为0.17℃/m,水体pH、电导率和溶解氧在温跃层具有同步变化特征;拉昂错湖水温跃层与玛旁雍错相比不明显,5~15 m间温度梯度为0.16℃/m,湖水pH与溶解氧呈反相变化,这可能与水生植物呼吸作用有关.2个湖泊湖水的主要离子组成特征除Ca²⁺外基本相同,拉昂错主要离子浓度约为玛旁雍错的3倍,而Ca²⁺则约为玛旁雍错的1/2;利用²¹⁰Pb和¹³⁷Cs方法对玛旁雍错和拉昂错的短岩芯进行了测试,结果表明2个湖泊近代沉积速率分别约为0.31 mm/a和0.65 mm/a.  相似文献   

西藏普莫雍错不同岩芯环境指标的对比研究及其反映的近200年来环境变化   总被引：4，自引：1，他引：3  

王君波  朱立平  鞠建廷  谢曼平  汪勇 《湖泊科学》2009,21(6):819-826

在西藏南部普莫雍错不同位置处采集了四支岩芯沉积物,对其中一支利用~(210)pb和~(137)Cs方法建立了沉积物的年代序列,并对其他三支岩芯的上部沉积物进行了总有机碳、无机碳、粒度及化学元素含量的分析.结合沉积物年代,对不同岩芯的环境代用指标进行对比,讨论了该地区近200年来的环境变化状况.结果表明,不同位置处采集的岩芯其环境指标变化趋势在整体上具有一定的可比性,但在细节变化与环境指标的数值上仍具有明显的差异,显示了湖泊内部沉积状况的空间差异性,这可能是由于采样点水深、水下地形以及与主要补给河流距离的不同而造成的.PY04岩芯环境指标显示普莫雍错湖区环境在约1900AD之前较为稳定;在约1900-1940AD之间湖区环境波动加剧,地表侵蚀增强,沉积速率加快;湖区环境在1940AD左右发生了明显的变化,温度显著升高,沉积物粒度增大,湖泊处于退缩状态,表明湖泊环境向暖干化方向发展.  相似文献   

1950年以来青藏高原兹格塘错碳酸盐稳定碳同位素变化及其原因   总被引：1，自引：1，他引：0  

类延斌  张虎才  李世杰  杨伦庆  姚书春  李春海  雷国良  张文翔 《湖泊科学》2010,22(1):143-150

兹格塘错是青藏高原中部一个典型的半混合型咸水湖泊。本文在~(210)Pb和~(137)Cs定年的基础上,研究了兹格塘错重力岩芯(ZGTC A-1)小于38.5μm细颗粒组分碳酸盐稳定碳同位素1950年以来的变化及其影响因素。对冬夏季湖水水化学特征的分析表明,夏季湖水溶解CO_2呈逸出状态,冬季湖水钙离子浓度是夏季湖水的10倍,据此可以得出兹格塘错碳酸盐矿物主要在夏季沉淀。通过与那曲气象站气象记录对比发现,1950年以来A-1岩芯碳酸盐碳同位素变化与年均温度有很好的相关性,表现出年均温度高时碳同位素偏重,而年均温度低时碳同位素偏轻的特征。兹格塘错1950年以来自生碳酸盐碳同位素的变化是由湖区及水体碳循环(如碳酸盐沉淀,有机质的沉淀与分解,有机碳和无机碳的转化等)的变化引起的,但各种因素的相互作用非常复杂。碳酸盐含量也与温度有关,温度越高,碳酸盐含量越高,同时降水量与碳酸盐含量也存在明显的相关关系。1950年以来有机质含量与温度呈反相关,可能与湖泊生产力的下降有关。  相似文献