1948—2018年国际河流跨境水冲突的时空演化规律     

王涛  刘承良  杜德斌 《地理学报》2021,76(7):1792-1809

随着全球气候变化和人类社会经济高速发展,水资源供需矛盾日益突出,国际河流流域跨境水冲突不断加剧,其时空演化规律成为当前跨学科研究的热点和难点。为此,从水冲突“事件—关系”视角,对1948—2018年间全球跨境水冲突的时空演化规律进行系统分析发现：① 1948—2018年全球跨境水冲突规模总体呈非单调波动增长态势,在1987年前后发生显著突变,表现出兼具趋势性、突变性和波动性等多维特征的非单调动力过程;② 全球跨境水冲突事件以围绕水文干预和资源权属争夺的低强度事件为主,大坝等水利工程建设引发的冲突显著增加,南亚、西亚和东非地区成为主导全球跨境水冲突趋势演化的“序参量”;③ 全球跨境水冲突呈现由单中心向多中心格局转变的空间扩散趋势,但“北多南少、东多西少、相对集中”的总体不均衡格局基本锁定,形成以30°N为中心、横跨南亚—中亚—西亚—东非高水资源压力区的水冲突密集带;④ 国家间跨境水冲突关系趋于普遍化、复杂化和网络化,发育多个流域性网络社团,但水冲突关系的“马太效应”和极化分布特征持续显著,产生“路径锁定”效应;水冲突“规模—强度”关系存在一定的空间错配。  相似文献   

气候变化对中亚草地生态系统碳循环的影响研究   总被引：1，自引：0，他引：1       下载免费PDF全文

韩其飞  陆研  李超凡 《干旱区地理》2018,41(6):1351-1357

准确评估草地生产力、碳源/碳汇功能,分析气候变化对草地生态系统碳循环的影响,对于草地资源的合理开发和有效保护至关重要。选取对气候变化以及人类干扰高度敏感的中亚干旱区草地生态系统为研究对象,利用Biome-BGC模型,模拟分析其NPP、NEP的年际变化趋势及其空间分布格局。结果显示：（1）1979-2011年中亚地区草地生态系统NPP年平均值为135.6 gC·m^-2·a^-1,且随着时间的推移呈现出波动下降的趋势,下降速率为0.34 gC·m^-2·a^-1。（2）NEP的年平均值为-8.3 gC·m^-2·a^-1,表现为碳源,且该值随着时间的推移呈现出波动上升的趋势,上升速率为0.58 gC·m^-2·a^-1。（3）NPP高值区域在降水较为丰富的天山山脉附近以及哈萨克斯坦北部。（4）NPP的年际变化与降水量的年际变化趋势基本一致,相关系数为0.52;NPP与温度的相关系数为-0.28,未达到显著相关水平。本研究实现了Biome-BGC模型在中亚干旱区草地生态系统的应用,对评价干旱区草地生态系统碳源/碳汇功能及其在全球碳循环和全球变化中的作用、实现中亚草地生态系统的可持续利用、完善区域和全球碳循环理论体系具有重要意义。  相似文献   

ASSESSMENT OF CLIMATE CHANGE AND FRESHWATER ECOSYSTEMS OF THE ROCKY MOUNTAINS,USA AND CANADA     

F. RICHARD HAUER  JILL S. BARON  DONALD H. CAMPBELL  KURT D. FAUSCH  STEVE W. HOSTETLER  GEORGE H. LEAVESLEY  PETER R. LEAVITT  DIANE M. MCKNIGHT  JACK A. STANFORD 《水文研究》1997,11(8):903-924

The Rocky Mountains in the USA and Canada encompass the interior cordillera of western North America, from the southern Yukon to northern New Mexico. Annual weather patterns are cold in winter and mild in summer. Precipitation has high seasonal and interannual variation and may differ by an order of magnitude between geographically close locales, depending on slope, aspect and local climatic and orographic conditions. The region's hydrology is characterized by the accumulation of winter snow, spring snowmelt and autumnal baseflows. During the 2–3-month ‘spring runoff’ period, rivers frequently discharge > 70% of their annual water budget and have instantaneous discharges 10–100 times mean low flow. Complex weather patterns characterized by high spatial and temporal variability make predictions of future conditions tenuous. However, general patterns are identifiable; northern and western portions of the region are dominated by maritime weather patterns from the North Pacific, central areas and eastern slopes are dominated by continental air masses and southern portions receive seasonally variable atmospheric circulation from the Pacific and the Gulf of Mexico. Significant interannual variations occur in these general patterns, possibly related to ENSO (El Niño–Southern Oscillation) forcing. Changes in precipitation and temperature regimes or patterns have significant potential effects on the distribution and abundance of plants and animals. For example, elevation of the timber-line is principally a function of temperature. Palaeolimnological investigations have shown significant shifts in phyto- and zoo-plankton populations as alpine lakes shift between being above or below the timber-line. Likewise, streamside vegetation has a significant effect on stream ecosystem structure and function. Changes in stream temperature regimes result in significant changes in community composition as a consequence of bioenergetic factors. Stenothermic species could be extirpated as appropriate thermal criteria disappear. Warming temperatures may geographically isolate cold water stream fishes in increasingly confined headwaters. The heat budgets of large lakes may be affected resulting in a change of state between dimictic and warm monomictic character. Uncertainties associated with prediction are increased by the planting of fish in historically fishless, high mountain lakes and the introduction of non-native species of fishes and invertebrates into often previously simple food-webs of large valley bottom lakes and streams. Many of the streams and rivers suffer from the anthropogenic effects of abstraction and regulation. Likewise, many of the large lakes receive nutrient loads from a growing human population. We concluded that: (1) regional climate models are required to resolve adequately the complexities of the high gradient landscapes; (2) extensive wilderness preserves and national park lands, so prevalent in the Rocky Mountain Region, provide sensitive areas for differentiation of anthropogenic effects from climate effects; and (3) future research should encompass both short-term intensive studies and long-term monitoring studies developed within comprehensive experimental arrays of streams and lakes specifically designed to address the issue of anthropogenic versus climatic effects. © 1997 John Wiley & Sons, Ltd.  相似文献   

生态遥感新锐——轻小型无人机的应用     

张菁  孙千惠  叶震  杨默含  赵晓霞  巨袁臻  胡天宇  郭庆华 《热带地理》2019,39(4):604-615

基于研究对象视角梳理轻小型无人机遥感手段在生态学研究中的应用现状,重点分析了无人机在不同生态对象应用的优势和局限：优势主要在于其能够高灵活性、高分辨率地获取各生态对象的数据,为较大规模的生态研究提供了便利。在农田生态系统应用中主要关注农田信息检测、自动化农作等方面,但在这方面的应用还比较单一,缺乏更深层更全面的系统化应用;在森林草地中主要关注植被结构参数提取、生物量反演等,在数据采集过程中应注意设备的稳定性避免对数据准确性造成影响;城市生态系统主要集中在城市环境监测和测绘方面,同时城市方面飞控政策尚待完善;水生生态系统主要关注水生动植物监测和潮间带观测等,大规模监测也对设备续航和数据标准化处理提出了要求;动物研究应用中主要关注动物迁徙规律、物种分布等方面,在监测过程中需注意不要对动物栖息造成干扰。总的来说,无人机应用局限主要在于其获取的数据处理尚未标准化,飞控政策尚未成熟和硬件续航等方面。在此基础上探讨了未来无人机遥感在生态学研究的应用趋势：随着无人机智能化的软硬件发展和云端生态大数据的建立,无人机数据的获取和处理将更加智慧化,多源的无人机遥感数据将会更好地服务于生态学研究。  相似文献   

Increased soil organic carbon storage in Chinese terrestrial ecosystems from the 1980s to the 2010s     

Xu  Li  Yu  Guirui  He  Nianpeng 《地理学报(英文版)》2019,29(1):49-66

Journal of Geographical Sciences - Soil stores a large amount of the terrestrial ecosystem carbon (C) and plays an important role in maintaining global C balance. However, very few studies have...  相似文献   

Estimation and analysis of the ratio of transpiration to evapotranspiration in forest ecosystems along the North-South Transect of East China     

Ren  Xiaoli  Lu  Qianqian  He  Honglin  Zhang  Li  Niu  Zhongen 《地理学报(英文版)》2019,29(11):1807-1822

Journal of Geographical Sciences - The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction...  相似文献   

淡水中对紫外光敏感的磷化合物研究简述     

周易勇  付永清  李建秋 《湖泊科学》2000,12(2):178-181

湖泊、沼泽与河流等淡水生态系统中在的一些对紫外光敏感的磷化合物,它们在紫外光（或太阳光）的作用下释放正磷酸根。本文对其形成释放机制、生态学意义以及铁和腐殖质的调节作用等作了扼要的综述。  相似文献   

鄱阳湖流域饶河龙口入湖段优势淡水鱼类对微塑料及重金属污染物的生物累积     

李文华  简敏菲  余厚平  阳文静  刘淑丽  倪才英  江玉梅 《湖泊科学》2020,32(2):357-369

水体生态环境中的微塑料与重金属污染问题正日益受到热切关注为探讨微塑料与重金属对水产品的复合生态效应,选择鄱阳湖饶河段优势淡水鱼为研究对象,对鱼体内微塑料及重金属Cu、Cd、Pb、Zn、Cr等元素的生物累积作用进行分析与评价结果表明:调查区域水环境中微塑料的丰度范围10～64 items/L,平均值38.56 items/L. 8种淡水鱼消化道微塑料丰度范围为1.21～9.11 items/g,平均丰度为5.40 items/g;鳃部丰度范围0.61～5.00 items/g,平均丰度为2.87 items/g;微塑料类型主要有碎片类、纤维类、薄膜类和颗粒类4种,其聚合物成分主要为聚乙烯(PE)、低密度聚乙烯(LDPE)、聚丙烯(PP)和聚苯乙烯(PS);颜色以透明及彩色为主;微塑料粒径范围为0.01～9.5 mm,粒径0.5 mm的微塑料所占比例为79.07%,鱼体内与其生存水环境中微塑料的丰度特征(形态、粒径、颜色和聚合物类型组分比例)具有一定相似性各鱼类对微塑料的累积系数(BAF)平均值为178.29,不同鱼类累积微塑料的能力大小次序为:乌鳢(Channa argus)、黄颡鱼(Pelteobagrus fulvidraco)鲦鱼(Hemicculter leuciclus)、草鱼(Ctenopharyngodon idellus)、鲶鱼(Silurus asotus)鲤鱼(Cyprinus carpio)、刀鱼(Coilia ectenes)、鲫鱼(Carassius auratus)鱼体肌肉组织内重金属Cu、Cd、Pb、Zn、Cr的平均含量分别为4.27、0.13、0.28、11.73、0.53 mg/kg,均符合无公害水产品的要求且低于人体消费卫生标准,属于安全食用范围;鱼类对5种不同重金属的累积能力大小次序为ZnCuCdPbCr,不同鱼类对不同重金属的累积能力具有差异性通过扫描电镜(SEM)与能谱分析(EDS)检测到各类型微塑料表面均有上述5种重金属元素,证实微塑料可能成为重金属的附着载体,相关性分析表明微塑料与Cu呈极显著相关,与Cd、Pb均呈显著相关;微塑料的存在一定程度上会增强Cu、Cd与Pb的累积效应,并可能产生复合污染效应.  相似文献   

Macrophyte‐driven transient storage and phosphorus uptake in a western Wisconsin stream          下载免费PDF全文

Katherine J. Bohrman  Eric A. Strauss 《水文研究》2018,32(2):253-263

Investigations of phosphorus cycling and transport in streams lend insight into potential mechanisms of nutrient sequestration and can help mitigate human impacts. In this study, we examined the relationship between transient storage and phosphorus uptake in a cold‐water stream in western Wisconsin. Hydrological characteristics, nutrient spiralling metrics, macrophyte biomass, and geomorphological properties were quantified in 7 reaches of Spring Coulee Creek using injections of a conservative tracer alone or with added PO₄^3?. Fraction of median travel time due to transient storage (F_med²⁰⁰) was correlated with macrophyte biomass (r = .794, p = .033), and PO₄^3? uptake velocity was correlated with F_med²⁰⁰ (r = .756, p = .049). Stepwise linear regression was used to build models for transient storage and uptake velocity. Macrophyte biomass, stream bed slope, and riffle to pool ratio accounted for 99.6% of the variation in transient storage (p < .001). Transient storage, canopy cover, and slope accounted for 98.0% of the variation in uptake velocity (p = .002). This study shows that transient storage, primarily resulting from macrophyte beds, can be a significant factor regulating phosphorus uptake in stream ecosystems.  相似文献   

老碳对水生态系统食物网的贡献     

胡恩  张振文  王文科  孙长顺  苏雅玲  刘正文 《湖泊科学》2018,30(5):1187-1195

传统理论认为,支撑水生态系统食物网的碳主要来自于系统内部的初级生产者,如藻类、大型水生植物等,或者来自陆源输入的新鲜且容易分解的有机质;而部分生物或非生物生产的有机碳,在冰川、冻土等环境中可停留数百年至数千年(定义为老碳),由于储存环境稳定、物理化学性质顽固,难以参与水生生态系统有机碳循环.近年来这一观念不断被挑战.研究表明老碳能够参与水生态系统食物网碳循环:可以被微生物分解利用;被浮游动物、无脊椎动物直接或者间接摄取、或沿着营养级传递至鱼类、水禽等高级消费者.这意味着除了内部初级生产,老碳是支撑水生态系统重要的碳源.本文概述了当前老碳与水生态系统食物网关系研究最新进展和所取得的研究成果,介绍放射性14C同位素技术在水生态学领域的应用,同时提出研究中存在的问题以及未来研究应关注的方向,以期促进我国水生态系统碳循环研究的进一步发展.  相似文献