Investigations on Aral Sea Regressions from Mirabilite Deposits and Remote Sensing

Remote sensing techniques including radar (Topex/Poseidon, Jason-1 and Envisat) and laser altimetry (Icesat), and moderate resolution spectro-radiometer (MODIS) images, are used to estimated current level and surface extent time variations of the Aral Sea. During the Holocene several phases of regression occurred, leading to desiccation of the Aral Sea. During the last 50 years, Aral Sea has drastically shrunk due to intense use of river’s water for irrigation purposes. It is currently separated into four distinct water bodies, namely, the Small Aral in the North, the Tchebas Bay in the North West, and the South West and the South East basins. The Kulandy strait connected the SW and SE basins until very recent times. These basins are now almost separated and salinity becomes very high (140–180 g/l) in the Eastern part. Rubanov discovered past deposits of mirabilite in the years 1970–1980. We investigate the significance of these deposits in the light of current evolution of the four water bodies that constitute the heritage of Aral Sea contemporary desiccation. Using remote sensing techniques, we have attempted to calculate the water balance of south Aral Sea during the last 3 years. We conclude in strong probability that the Kulandy strait carries water most of the time from the Eastern Basin to the Western Basin. We have demonstrated that it should have been the same process in the past to explain the Mirabilite deposit, but unfortunately, due to recent artificial water monitoring of the Aral Sea (dam in the Berg’s strait, new reservoirs in the Amu Darya’s delta), it is impossible to make definitive conclusion from actual Aral Sea water balance.     

咸海流域水文水资源演变与咸海生态危机出路分析

中亚的咸海问题已成为全球性的生态和社会问题,研究咸海流域水文水资源、经济社会发展演变与气候变化,对深入理解中亚地区咸海危机形成机理、未来发展趋势、探讨咸海生态危机出路具有重要意义,对类似区域跨界河流和我国西北干旱区水资源开发利用具有重要借鉴意义. 介绍了中亚五国咸海流域的水资源及其开发利用情况,重点分析了中亚五国咸海流域农业灌溉的发展演变、近80a来咸海流域气候变化趋势与主要河流水文演变情势及咸海水文特征演变. 结果表明,咸海生态危机完全是由人类自导并日益严重的水资源-生态-环境与社会危机,短期内难以遏制,长期来看也无法逆转. 结合咸海危机生态环境效应,讨论了3个跨流域调水方案拯救咸海的利弊与前景,探讨了立足于流域本身拯救咸海的综合治理措施. 最后,提出了咸海危机经验教训对我国内陆河水资源开发利用的若干启示.     

1962—2019年锡尔河-咸海三角洲湿地时空变化及驱动因素

咸海周边环境变化对中亚干旱区生态稳定有重要影响,研究锡尔河-咸海三角洲湿地演变对认识流域生态环境变化、实施生态修复等具有重要意义。基于多源遥感数据采用面向对象分层提取法方法,分析1962—2019年锡尔河下游三角洲湿地的时空变化特征,并结合咸海变化、耕地变化、河流水量和水利工程建设等探讨近60a湿地变化的驱动因素。研究表明:①近60 a在咸海持续萎缩的情况下,锡尔河下游三角洲湿地呈现先减小后增加的变化趋势,其中1962—1980年、1981—1991年和1992—2019年3个阶段的变化率分别为-38.29 km2/a、193.35 km2/a和14.36 km2/a;②湿地变化有明显的空间差异,锡尔河南、北2个入湖口区的湿地自1980年以来向咸海湖区扩张明显,耕地混合区的湿地自1991年以来向河道两侧扩张;③ 1962年后在入三角洲径流量总体减少的趋势下,灌渠建设和生态用水配置是三角洲湿地面积增加的主要原因,间接导致咸海入湖水量减少,咸海快速萎缩。锡尔河三角洲湿地恢复与咸海干涸形成了明显的生态反差,不利于咸海周边生态的整体恢复。     

Ongoing Changes of Ionic Composition and Dissolved Gases in the Aral Sea

Starting from 1961, the Aral Sea, a major saline lake in Central Asia, has been continuously shrinking because of deficiency in its water budget. Accordingly, the salinity of the once brackish lake increased by a factor of magnitude. During the desiccation, the salt composition of the Aral Sea has been subject to continuous changes because of chemical precipitation accompanying the salinity buildup. This paper provides a summary of these changes based on water samples collected from the so-called Large Aral Sea during the field surveys of 2002–2007. Once fully ventilated, the lake developed anoxic conditions and H₂S contamination is frequently observed in the bottom layers. However, hydrogen sulfide is a variable rather than a permanent feature of the present Aral Sea. Because of the precipitation of calcium carbonate, gypsum, and, possibly, mirabilite, which successively occurred as the salinity increased, the relative content of SO₄ ^? and Ca²⁺ ions decreased. Accordingly, compared with the pre-desiccation period before 1960, the sulfate-to-chloride mass ratio decreased by 10–30%, while the relative content of calcium decreased almost 7-fold. The depletion in calcium is more pronounced in the shallow eastern part of the lake, where salinity is much higher. However, the reduction of the sulfate-to-chloride ratio in the eastern basin is smaller than that for the western basin of the Aral Sea. Hypothetically, this could be explained through precipitation of halite already taking place in the eastern basin, but not yet in the western basin. Vertical profiles of the ionic content in the relatively deep western part of the lake reveal a decrease of calcium content and relative increase of sulfate ion content toward the bottom, which is consistent with the previously published concept that the bottom layers of the western trench contain a significant admixture of the water advected from the eastern basin.     

A high-resolution diatom-inferred palaeoconductivity and lake level record of the Aral Sea for the last 1600 yr

Formerly the world's fourth largest lake by area, the Aral Sea is presently undergoing extreme desiccation due to large-scale irrigation strategies implemented in the Soviet era. As part of the INTAS-funded CLIMAN project into Holocene climatic variability and the evolution of human settlement in the Aral Sea basin, fossil diatom assemblages contained within a sediment core obtained from the Aral Sea have been applied to a diatom-based inference model of conductivity (r² = 0.767, RMSEP = 0.469 log₁₀ μS cm^− 1). This has provided a high-resolution record of conductivity and lake level change over the last ca. 1600 yr. Three severe episodes of lake level regression are indicated at ca. AD 400, AD 1195–1355 and ca. AD 1780 to the present day. The first two regressions may be linked to the natural diversion of the Amu Darya away from the Aral Sea and the failure of cyclones formed in the Mediterranean to penetrate more continental regions. Human activity, however, and in particular the destruction of irrigation facilities are synchronous with these early regressions and contributed to the severity of the observed low stands.     

近500年来咸海湖泊沉积记录的环境演变

过去的五十年里,作为曾经世界第四大湖泊的咸海面积急剧萎缩,环境质量严重下降并对大部分中亚地区造成了灾难性的影响.咸海的水位下降过程虽然历时相对较短却变化显著,为了了解这一变化的详细过程,1997年从咸海北部湖盆采集了AS17孔浅钻岩芯.通过对该岩芯的矿物学、介形虫、孢粉等沉积环境指标综合分析,结果表明岩芯在矿物学特征及生物特征上的一系列显著变化,揭示了过去近500年中咸海的沉积环境经历了含盐量增加-下降-再增加三个明显的阶段,并为15世纪咸海的干旱提供了新的证据.     

Natural and anthropogenic rapid changes in the Kara-Bogaz Gol over the last two centuries reconstructed from palynological analyses and a comparison to instrumental records

Palynological analyses (pollen and dinocysts) of a sediment core taken in the Kara-Bogaz Gol have been used to reconstruct rapid and catastrophic environmental changes over the last two centuries (chronology based on ²¹⁰Pb). A natural cyclicity (65 years) of water level changes in the Caspian Sea (CS) and in the Kara-Bogaz Gol (KBG) and anthropogenic factors (building of a dam separating the CS and the KBG waters) combine to induce rapid changes in water levels of the KBG, in the salinity of its waters and in vegetation cover of its surroundings. The impact of low water levels on the dinocysts is marked by a lower diversity and the survival of two species that are typical of the KBG, the Caspian Sea species present in the KBG having disappeared. During periods of higher water levels (AD 1871–1878), the lake is surrounded by a steppe-like vegetation dominated by Artemisia; whereas during periods of low water levels (AD 1878–1913 and AD 1955–1998), the emerged shore are colonised by Chenopodiaceae. The period of AD 1913–1955 corresponding to decreasing water levels has an extremely low pollen concentration and a maximum of reworking of arboreal taxa. During the last low-level period, humans responded by abandoning the shores of the bay. What happened to the KBG can be used as an example of what may happen in the future for the Aral Sea.A problem of reworking of Tertiary dinocysts into modern deposits has been detected owing to the knowledge of the modern dinoflagellate assemblages recently made available through a water survey. A comparison to modern surface pollen samples from Central Asia (Anzali, Caspian Sea south and central basins, Aral Sea, Lake Balkhash, Lake Issyk-Kul and the Chinese Tien-Shan range) allows us to establish the potential reworking of at least five arboreal pollen taxa possibly by run-off and dust storms.     

中亚各国在咸海流域水资源问题上的冲突与合作

咸海流域是中亚社会发展进程中水资源供需矛盾和生态环境问题表现最为突出的区域,已严重妨碍了经济发展和社会稳定,甚至严重影响到中亚国家间的关系. 在解决咸海问题上,中亚各国虽然都表现出了极度忧虑和希望合作解决共同问题的诚意,签订了一系列的多边和双边合作协议,付诸了较多的行动;发达国家和国际组织也多方介入,大力援助、积极斡旋,但仍未从根本上缓解咸海危机. 深入分析介绍了咸海流域的水资源及开发利用情况、中亚各国在咸海流域水资源问题上的冲突以及开展的一系列合作,探讨了咸海危机的潜在水冲突,提出了合理利用水资源,实现流域一体化管理,化解咸海危机的对策措施.     

Surface water and aerosol spatiotemporal dynamics and influence mechanisms over drylands

Under the background of global warming and excessive human activities, much surface water in drylands is experiencing rapid degradation or shrinkage in recent years. The shrinkage of surface water, especially the degradation of lakes and their adjacent wetlands in drylands, may lead to the emergence of new salt dust storm hotspots, which causes greater danger. In this paper, based on high spatial resolution global surface water (GSW) and multiangle implementation of atmospheric correction (MAIAC) AOD data, we systematically analyze the dynamic characteristics of surface water and aerosols in typical drylands (Central Asia, CA) between 2000 and 2018. Simultaneously, combined with auxiliary environment variables, we explore the driving mechanisms of surface water on the regional salt/sand aerosols on different spatial scales. The results show that the seasonal surface water features an increasing trend, especially a more dramatic increase after 2015, and the permanent surface water indicates an overall decrease, with nearly 54.367 % at risk of receding and drying up. In typical lakes (Aral Sea and Ebinur Lake), the interannual change feature of the surface water area (WA) is that a continuous decrease during the study period occurs in Aral Sea area, yet a significant improvement has occurred in Ebinur Lake after 2015, and the degradation of Ebinur Lake takes place later and its recovery earlier than Aral Sea. The aerosol optical depth (AOD) in CA shows obvious seasonal variation, with the largest in spring (0.192 ± 0173), next in summer (0.169 ± 0.106), and the smallest in autumn (0.123 ± 0.065). The interannual variation of AOD exhibits an increase from 2000 to 2018 in CA, with high AOD areas mainly concentrated in the Taklamakan Desert and some lake beds resulting from lake degradation, including Aral Sea and Ebinur Lake. The AOD holds a similar trend between Aral Sea and Ebinur Lake on an interannual scale. And the AOD over Ebinur Lake is lower than that over Aral Sea in magnitude and lags behind in reaching the peak compared with Aral Sea. The WA change can significantly affect aerosol variation directly or indirectly on the aerosol load or mode size, but there are obvious differences in the driving mechanisms, acting paths, and influence magnitude of WA on aerosols on different spatial scales. In addition, the increase of WA can significantly directly suppress the increase of Ångström exponent (AE), and the effects of WA on AOD are realized majorly by an indirect approach. From the typical lake perspective, the effects of WA on aerosol in Aral Sea are achieved via an indirect path; and the decrease of WA can indirectly promote the AOD rise, and directly stimulate the AE growth in Ebinur Lake.     

北戴河潮间带现代介形虫的分布

由北戴河潮间带的12个样品分析得到介形虫29属46种。由于具体的小生境,缺少淡水介形虫, 北戴河潮间带底栖动物丰富,介形虫组合的主要特征与胶州湾东北角小海湾及东、黄海潮间带和潮下带介形虫的组合相似。在风化、潮汐和波浪等作用下,潮间带介形虫的壳体表面受机械磨蚀和破坏保存不好,充分反映出其异地埋藏特点。 通过研究北戴河潮间带介形虫,为研究我国辽阔沿海地区潮间带和潮下带介形虫的组合特征、分布范围及地理分区提供了很有价值的资料,并对海洋地质学、古生态学及沉积相等的研究具有重要意义。     

中亚干旱区咸海面积变化与人类活动及气候变化的关联研究

咸海是亚洲仅次于里海的第二大内陆咸水湖, 20世纪60年代以来湖泊面积急剧萎缩。基于1960 - 2018年咸海的面积数据、 CRU气温和降水数据以及咸海流域灌溉面积、 水库容量等资料, 定量分析了1960年以来咸海湖泊面积的变化情况, 并从气候变化与人类活动两方面探究了咸海面积变化的主要影响因素。结果表明： 1960 - 2018年咸海的面积由6.85×10⁴ km²持续萎缩至（8.32±0.19）×10³ km², 共减少了（6.02±0.02）×10⁴ km²（约87.85%）, 其中1960 - 2009年面积萎缩了（5.94±0.02）×10⁴ km²（约86.77%）, 而在2009 - 2018年其面积萎缩速率明显放缓, 减少了740.04 km²（约8.17%）。统计结果显示, 1960年以来强烈的人类活动（主要表现为灌溉用水和水库储水量的持续增加）是导致咸海面积急剧萎缩的主要因素, 其对咸海面积变化的影响远大于气候变化。在中亚地区气候继续向暖湿变化的背景下, 咸海流域应尽快调整以农业灌溉为主的用水结构, 否则在上游冰川融水达到峰值后, 咸海可能面临干涸的危险。     

中亚干旱区的荒漠化与土地利用

笔者在实地考察、航片和卫星影像判读的基础上,参考国际上最新研究成果,以咸海盆地和古丝绸之路沿线地区为例,分析探讨了中亚干旱区荒漠化发生的过程、机制及其对自然和人文环境系统的影响和危害。由于大量从阿姆河和锡尔河引水扩大灌溉、浪费水源及单一农作物种植,使1960年时还为世界第四大湖的威海水面和蓄水大减,在干枯了的湖底和周围耕地上荒漠化快速发展,造成自然环境系统的严重退化和社会经济的巨大损失。虽然在我国丝绸之路沿线地区自古以来就有荒漠化现象,但荒漠化的规模在近40年来发生了根本性变化。塔里木河下游和克里雅河下游及玛纳斯河下游的湖泊干枯,植被退化甚至消失,不少野生动物灭绝。     

The demise of the Aral Sea – an environmental disaster

The shrinkage of the Aral Sea ranks as one of the world's greatest man-made environmental disasters. While there is some hope for a separated northern part, the main sea is doomed     

咸海和巴尔喀什湖水文变化与环境效应对比

以咸海和巴尔喀什湖流域为研究对象,采用定性和定量分析相结合的途径,对两个湖泊的水文特征、主要补给河流的入湖径流特征、流域人类活动情况、生态环境问题及未来趋势等进行对比,分析咸海和巴尔喀什湖流域各方面的异同。研究发现:咸海的水位变化呈现相对单一趋势,从1960年开始急剧下降并于2009年分裂成4个水体;巴尔喀什湖的水位变化呈现明显周期性波动,从1970年开始出现下降并于1987年降至历史最低水位;目前的咸海仍不容乐观并将面临最终干涸,巴尔喀什湖正值丰水期并将进入枯水周期。在咸海和巴尔喀什湖两个跨界河流-湖泊流域的水资源和生态环境保护中,流域各国均负有重要责任。     

气候变化和人类活动对中亚地区水文环境的影响评估

中亚地区是我国天气的上游区,生态环境异常脆弱,必须要保证该地区生态环境和资源安全,水资源安全首当其冲.研究和评估气候变化和人类活动对中亚地区水文环境的影响,具有重要的战略意义.近百年来中亚地区气候有暖湿化趋势,气温增温持续时间较长且增温幅度较大,近50a增暖更加明显(0.47℃·(10a)^-1),其中冬季增温最快,预估未来会延续变暖的态势;同时20世纪80年代之后降水量持续波动上升.气候变化对该地区水资源的时空分布及湖泊变迁造成了重大影响,人类活动加剧了水资源短缺,近50a来锡尔河和阿姆河入咸海径流量均呈减少的趋势,20世纪70年代之后拦水蓄水水库等水利工程的建设,加上灌溉用水的增加,导致两河入咸海水量骤减;而1987年之后两河入咸海水量回升,主要是气温回暖、降水增多,加速了常年积雪和冰川融化,使得进入河道的径流量增加.同时,湖泊水位下降,面积收缩,水质恶化.中亚水资源问题主要是跨国水资源分配和水环境恶化问题,要做好水资源评估和用水规划工作,建立覆盖全区域的水资源环境监测网络.中亚国家需要共同参与制定一套完整的、综合考虑人口、社会经济、生态环境等因素的水资源管理政治立法决策体系,构建中亚各国人水和谐、互利共存的水资源新秩序,以水资源可持续利用来支持经济与社会的可持续发展.     

Late glacial and Holocene Ostracoda from the Melilla cold-water coral mound field

The ostracod assemblages from sediment core TTR17-401G recovered from the Melilla cold-water coral mound field in the eastern Alboran Sea spanning the last 13 ka are analysed quantitatively, taxonomically and palaeoecologically. The core can be subdivided in three distinct assemblages linked to environmental shifts during the Younger Dryas and the Bølling–Allerød interstadial. A total of 9 ostracod species is recorded, Paracypris polita is dominant throughout the core. Common accessory taxa Cytherella robusta, Echinocythereis vidua and Macromckenziea ligustica characterize the well-oxygenated ostracod assemblage 2 affected by the Younger Dryas. Favourable growth conditions for ostracods during the latter are indicated by large-sized Krithe praetexta specimens.     

Le système régional d'action éolienne (SRAE) du bassin de l'Aral (Kazakhstan,Ouzbékistan et Turkménistan)The regional Aeolian action system of the Aral Basin

The endorheic basin of the Aral Sea, a tectonic depression resulting from two Tertiary fault bundles, NNE–SSW and east–west ones, represents the termination of a flow by closure of the Aral Basin opposite Central Asia and Siberia. The conditions of Quaternary climate and sediment deposition, especially aridity increased by coldness, a pedogenesis inhibitor, and absence of palaeosoils favour the activity of the Aralian Regional Aeolian Action System (RAAS), 700 km long. Such a system develops in a lowland topography where wind, in a progressive shift, reconstructs by deflation the sandy material resulting from Pleistocene accumulations, gives rise to thin and vulnerable ergs and explains at once the fertility of Khoresm and the dewatering of the Aral Sea, which is one of the most complex and severe ecological catastrophe in the 20th century. To cite this article: M. Mainguet et al., C. R. Geoscience 334 (2002) 475–480.     

中亚五国水土资源开发及其安全性对比分析

由于气候变暖和人类活动的影响,随着人口增长和区域农业灌溉发展,再加上低效率水资源管理等已导致中亚区域水土生态系统的退化.主要针对前苏联解体后到2007年的时段,对中亚五国水土资源开发情况及其对安全状态指标进行对比分析.结果表明:在1988—2007年期间,哈萨克斯坦人口总数逐年减少,人均可更新水资源量和人均总取水量呈逐年增加的趋势;其它中亚4国(吉尔吉斯斯坦、塔吉克斯坦、土库曼斯坦和乌兹别克斯坦)人均水资源量出现逐年降低的趋势;乌兹别克斯坦是最大取水用户国家,次为土库曼斯坦;乌兹别克斯坦和土库曼斯坦是最大农业取水国,哈萨克斯坦是最大工业取水国,乌兹别克斯坦是最大生活取水国.到2005年,塔吉克斯坦和土库曼斯坦的淡水产量降到1989年的99%.在1992—2005年间,除了土库曼斯坦外其它中亚国家人均耕地面积逐年减少;同期,哈萨克斯坦的森林和草地面积有所减少,吉尔吉斯斯坦和乌兹别克斯坦有所扩大,塔吉克斯坦和土库曼斯坦的森林面积基本上保持不变,草地面积有所降低.乌兹别克斯坦是化肥施用和土壤盐渍化强度较严重的国家,土壤盐渍化面积占总灌溉面积从1994年50%扩大到2001年65.9%.     

Mixed marine,brackish water and non-marine microfaunal association in the Inter-trappean beds (Early Palaeocene) of Jhilmili,Chhindwara district,Madhya Pradesh

Except for the east coast of Andhra Pradesh, the Deccan Inter-trappean sedimentary beds of Peninsular India have been long known to yield non-marine microfauna, mainly ostracods. These have been extensively described from different localities of Madhya Pradesh, Maharashtra, Karnataka, Andhra Pradesh, Gujarat and Rajasthan states. Occurrence of mixed microfaunal association of marine, brackish water and non-marine foraminifers and ostracods is being recorded from these beds from Jhilmili, Chhindwara district, Madhya Pradesh. It comprises at least two or more planktonic foraminifer species, and one brackish water and 17 non-marine ostracod species. The brackish water ostracod, Neocyprideis raoi (Jain, 1978) has been previously recorded in great profusion from the Inter-trappean beds of Duddukuru, West Godavari District, Andhra Pradesh, which have been assigned Early Palaeocene age (Khosla and Nagori, 2002). Presence of molt stages of the bulk of non-marine and brackish water ostracods in the Inter-trappean beds of Jhilmili is suggestive that they were inhabitants of low mesohaline inland pool/lake. The planktonic foraminifers were carried to this pool/lake by a marine transgression probably from the east coast of India through the Trans Deccan Straits.