Mechanism and control of lake eutrophication

China is rich in lakes. The total lake area is 91000 km2 in which approximately one third, namely 27000 km2, is the fresh water lake[1]. In these fresh water lakes, about 16558 km2 (accounting for 60% of total fresh water lake area) is located in the midd…     

基于LEGOS HYDROWEB的青藏高原湖泊群水位和面积动态变化分析

湖泊面积和水位的变化客观地反映了区域水资源的时空变化过程。利用LEGOS HYDROWEB提供的湖泊信息数据,对青藏高原1993~2014年21年间63个典型湖泊的水位变化,以及其中59个湖泊的面积变化趋势进行分析。根据变化趋势将湖泊分为增长型、稳定型和衰退型;并在这三种类型的湖泊中分别选取两个典型湖泊进行回归分析。结果表明:63个湖泊中水位增长型湖泊42个,稳定型湖泊12个,衰退型9个;59个湖泊中面积增长型湖泊32个,稳定型19个,衰退型8个。对于增长型湖泊而言,水位和面积增长最大是Ziling湖,分别增长了10.90 m和361.72 km~2;衰退型湖泊中水位和面积衰退趋势最大的是Yamzho-yumco湖,分别减少了2.29 m和28.65 km2。高原内陆水体的水位和面积的动态变化对研究气候演变和地表水资源的影响具有重要意义。     

武汉市城市湖泊演化及开发利用初探

城市湖泊主要指位于建成区及其邻近正在非农化地区中的湖泊,也包括位于中心城市周围点状展布的卫星城镇区域范围内的湖泊．在分析武汉市湖泊现状特征的基础上,探讨了三国时期以来武汉市城市湖泊演化的过程与规律,提出了武汉市湖泊开发利用的基本思路．指出武汉市城市湖泊众多,可分为东沙湖水系、汤逊湖水系、北湖水系、墨水湖-龙阳湖-南太子湖（北太子湖）水系、东西湖水系等湖泊群．认为它们的形成演化、开发利用和保护同城市化过程关系极为密切,明代以来武汉市湖泊变化最为显著．提出了合理永续利用湖泊资源、发展湖泊经济、建设“湖城武汉”、加大湖泊保护力度等建议和对策．     

北京六湖水体和表层沉积物中氮污染特征与评价

调查和分析了北京市六个城市湖泊水体和沉积物的氮营养盐污染特征和污染程度,并对六湖水体和表层沉积物中各指标作了相关分析,拟为城市湖泊富营养化的防治提供基础数据.结果表明,所调查的北京城市湖泊氮污染程度较严重,调查期间半数湖泊的水体总氮(TN)含量超过地表水(湖、库)Ⅴ类标准值.在太湖流域的有机氮(ON%)污染评价标准下,...     

江汉平原湖泊的成因类型及其特征

对江汉平原湖泊的成因进行了探讨和分类，并描述了各类湖泊的特征，江汉平原是一典型的洪泛平源，江汉湖群大多是长江，汉江及其支流演化过程中的伴生湖泊，是长江，汉江的侵蚀与堆积地貌的有机组成部分，江汉湖群在成因上可划分为6种类型，即河间洼地湖，岗边湖，壅塞湖，河谷沉溺湖，牛轭湖，河堤决口湖，由于它们是在共同的自然地理背景下形成的，所受内外营务相似，因而有着许多共同的特征，如湖水浓度一般不超过8m，湖底平坦，湖底淤泥深厚，有机质含量高等。     

青海盐湖水化学特征的因子分析研究

采用最大方差正交旋转因子分析方法研究青海盐湖水化学特征，结果表明，青海盐湖水化学类型主要为硫酸镁盐型，盐湖卤水发育程度较深，没有碳酸盐型，K、Na、Mg//Cl、SO4-H2O是青海盐湖卤水的主要化学平衡体系等，这与青海盐湖的实际情况完全相符。     

1990—2020年那曲地区冰湖变化研究

基于Landsat遥感影像,采用目视解译的方法提取了青藏高原内部那曲地区冰湖和冰川1990、2000、2010及2020年4期边界数据,并分析近30年来该地区冰湖变化的特征与原因．结果表明:那曲地区现有冰湖255个,总面积（27.829±4.62） km2,冰湖主要集中在东南部,其次是西南部;1990—2020年,研究区新增冰湖72个,面积增长6.14 km2;冰湖扩张趋势明显,具体表现为低海拔地区（≤4 700 m）原有冰湖快速扩张,较高海拔地区（>5 100~5 700 m）新增冰湖集中出现;气温与降水是冰湖变化的关键因素,由于降水与气温分布及变化存在时空差异,冰湖变化呈现“南快北慢,逐期加快”的特征;冰湖与冰川的位置关系也会影响冰湖变化,离冰川位置越近,对冰湖发育越有利,同时与冰湖接触的冰川退缩速率相较于其余冰川有更大的退缩速率,但冰川与冰湖面积变化速率并无明显相关性．      

西藏盐湖的钾盐资源

 西藏盐湖赋存锂、硼、钾等特种资源及普通盐类。综述了西藏盐湖调查历史,对已勘查盐湖的钾盐资源储量和已详细取样调查盐湖的钾盐资源量分别进行了汇总与估算,阐述了盐湖成矿物质来源及西藏盐湖钾盐资源远景。西藏盐湖钾盐资源以中小型为主,钾含量较高但规模较小,而其伴生矿锂、硼的矿床规模大,建议三者综合开采,以取得最大效益。     

The lakes of Titan

The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70 degrees north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table.     

Water balance estimates of ten greatest lakes in China using ICESat and Landsat data

Lake level and area variations are sensitive to regional climate changes and can be used to indirectly estimate water balances of lakes. In this study, 10 of the largest lakes in China, ～1000 km² or larger, are examined to determine changes in lake level and area derived respectively from ICESat and Landsat data recorded between 2003 and 2009. The time series of lake level and area of Selin Co, Nam Co, and Qinghai Lake in the Tibetan Plateau (TP) and Xingkai Lake in northeastern China exhibit an increasing trend, with Selin Co showing the fastest rise in lake level (0.69 m/a), area (32.59 km²/a), and volume (1.25 km³/a) among the 10 examined lakes. Bosten and Hulun lakes in the arid and semiarid region of northern China show a decline in both lake level and area, with Bosten Lake showing the largest decrease in lake level (?0.43 m/a) and Hulun Lake showing the largest area shrinkage (?35.56 km²/a). However, Dongting, Poyang, Taihu, and Hongze lakes in the mid-lower reaches of the Yangtze River basin present seasonal variability without any apparent tendencies. The lake level and area show strong correlations for Selin Co, Nam Co, Qinghai, Poyang, Hulun, and Bosten lakes (R ² >0.80) and for Taihu, Hongze, and Xingkai lakes (～0.70) and weak correlation for East Dongting Lake (0.37). The lake level changes and water volume changes are in very good agreement for all lakes (R ² > 0.98). Water balances of the 10 lakes are derived on the basis of both lake level and area changes, with Selin Co, Nam Co, Qinghai, and Xingkai lakes showing positive water budgets of 9.08, 4.07, 2.88, and 1.09 km³, respectively. Bosten and Hulun lakes show negative budgets of ?3.01 and ?4.73 km³, respectively, and the four lakes along the Yangtze River show no obvious variations. Possible explanations for the lake level and area changes in these four lakes are also discussed. This study suggests that satellite remote sensing could serve as a fast and effective tool for estimating lake water balance.