scholarly journals Anthropogenic Influences on Environmental Changes of Lake Bosten, the Largest Inland Freshwater Lake in China

2020 ◽  
Vol 12 (2) ◽  
pp. 711 ◽  
Author(s):  
Wen Liu ◽  
Long Ma ◽  
Jilili Abuduwaili
Keyword(s):  
Central Asia ◽  
Lake Sediments ◽  
Human Activities ◽  
Environmental Changes ◽  
Living Environment ◽  
Water Levels ◽  
Aral Sea ◽  
Anthropogenic Factors ◽  
Large Spatial Scale ◽  
The 1960S

A short lacustrine sediment core (41 cm) from Lake Bosten in arid central Asia was used to investigate the environmental changes that occurred in the past ≈150 years based on the superposition of climate and anthropogenic factors. Geochemical elements, total organic carbon (TOC) and nitrogen (TN), and stable isotope data (δ13Corg and δ15N) were used to identify abnormal environmental changes. The average C/N ratio in the sediments of Lake Bosten suggested that the organic matter in lake sediments was mainly from aquatic plants. The δ13Corg and δ15N in the lake sediments mainly reflect changes in the structure of the lake’s ecosystem. Before the 1960s, the primary productivity of the lake was relatively low with a relatively stable lake water environment. From the 1960s to the mid-1980s, the lake’s ecosystem was closely related to a significant decline in water levels caused by human activities and an increase in salinity. From the late 1980s to ≈2000, the aquatic plant structure of Lake Bosten did not change significantly. After 2000, the upper part of the sedimentary record suggested enhanced productivity due to urban and industrial development in the catchment area. However, sedimentary perspectives of the responses of different environmental proxies in sediments to human activities were anisochronous, and the increasing heavy metal (Pb and Cu) and P accumulations appeared in 1970, reflecting heightened human impacts. Through the comparison between the Aral Sea and Lake Bosten, it was inferred that, under the intervention of human activities, the lake experienced a completely different evolution trend. Humans, as geological agents, should protect our living environment while satisfying social development. The results will provide an important supplement to a large spatial scale study of the influences of human activities on the environment in Central Asia, which also has some significant implications for the protection of the ecological environment and the realization of sustainable development in arid regions.

scholarly journals Environmental variability and human activity over the past 140 years documented by sediments of Ebinur Lake in arid central Asia

2017 ◽  
Author(s):  
Wen Liu ◽  
Long Ma ◽  
Jinglu Wu ◽  
Jilili Abuduwaili
Keyword(s):  
Heavy Metal ◽  
Magnetic Susceptibility ◽  
Organic Matter ◽  
Central Asia ◽  
Human Activities ◽  
Arid Central Asia ◽  
Ebinur Lake ◽  
Metal Contents ◽  
The 1960S ◽  
Environmental Proxies

<p>A short (50-cm-long) sediment core from Ebinur Lake in arid central Asia has been analyzed for various environmental proxies, including organic matter content, δ<sup>13</sup>C in organic matter, magnetic susceptibility, heavy metal contents, and stable isotopic compositions of bulk carbonate (δ<sup>18</sup>O and δ<sup>13</sup>C). The results reveal that the evolutionary stages inferred from environmental indicators have an asynchronous nature. If the asynchrony of periodic changes in multi-environmental proxies is ignored, important information may be lost, especially regarding anthropogenic influences. On the basis of magnetic susceptibility and heavy metal contents, human activities appear to have resulted in increases in surface erosion and measurable heavy-metal accumulation from the mid-1960s, whereas the organic matter contents, which display an obvious shift in the late 1930s, correlate with regional climate. However, the changes in the stable isotopes of bulk carbonate are mainly controlled by the isotopic composition of the host water which is generally consistent with the lake level. From the late 1870s to the 1960s, the lake was in a natural evolutionary state. From the 1960s to the mid-2000s, the runoff feeding Ebinur Lake dropped rapidly, in association with a sharp increase in agricultural development. Finally, beginning in the early twenty-first century, the climate became wetter than during the earlier two stages, and as agricultural water demand decreased, surface runoff once again increased. It is noted that, although the different proxies respond differently to climate changes and human activities, any analysis of environmental evolution should consider them each individually, in order to fully understand the complex interactions between climate and human influence. </p>

Paleoclimatic reconstruction studies in lake sediments: major proxies, technical evolution and database

2020 ◽  
Author(s):  
Paula Bianchini ◽  
Elder Yokoyama ◽  
Luciana Prado
Keyword(s):  
Lake Sediments ◽  
Climate Changes ◽  
Environmental Changes ◽  
Drainage Basin ◽  
Spatial Scales ◽  
Temporal Variations ◽  
Quality Data ◽  
Anthropogenic Factors ◽  
Data Sets ◽  
Geochemical Composition

&lt;p&gt;Paleoclimate studies in different temporal and spatial scales provide important information on long-term statistics required to test hypotheses about climate changes. Comprehensive high-quality data sets and a solid understanding of dynamic climate processes in different temporal variations are essential to evaluate the sensitivity of the climatic system. Moreover, these data sets and dynamic analyses can help to distinguish the variability of natural and anthropogenic factors, reducing uncertainties about the magnitude and impact of future global climate changes. A common way to conduct paleoclimatic studies is through high resolution multiproxy lake sediments. Lake environments have been increasingly used in recent years to infer past fluctuations in climate, and many studies that comprise different locations and timescales demonstrate the great value of lakes as paleoclimatic archives. Because lake sediments are continental indicators sensitive to environmental changes, they can be used to reconstruct climate parameters, such as past rainfall, area management and environmental or limnological lake conditions. Changes of rainfall quantity can be recorded in lake archives by the variation of sedimentary input, which is related to changes in drainage basin and erosion rate. Beside of sedimentary input, lake sediments also exhibit physical and chemical changes in water bodies which, in turn, induce transformation in geochemical composition caused by changes in runoff or other allocated components. Thus, there is a variation in the proxies used in the studies, both in relation to the type of proxy used and the relationship used. In this context, we made a compilation of paleoclimatic studies on lake sediments (about 350 lakes), focusing on the main proxies used. Our study shows that there has been a change in the major proxies used along decades and with the emergence of new analysis techniques. In addition, we notice that lake characteristics (e.g., shape, geomorphological context, formation, etc.) have directly influence the proxies used and the quality of the information obtained. This compilation provides a database with an analysis of several lakes around the world, which can help future works and enable the identification of commonly used proxies according to the different variables that should be used, promoting more objective analyzes.&lt;/p&gt;

XI. The 'Power of Water' in a Divided Central Asia

2003 ◽  
Vol 2 (3) ◽  
pp. 593-614 ◽  
Author(s):  
Anatoly Krutov ◽  
Max Spoor
Keyword(s):  
Central Asia ◽  
Water Reservoir ◽  
Mineral Resources ◽  
Aral Sea ◽  
Hydroelectric Power ◽  
Ferghana Valley ◽  
Interethnic Conflict ◽  
Independent States ◽  
The 1960S ◽  
Soviet Central Asia

AbstractIn the not-too-distant future, the former Soviet Central Asia could be confronted with resource-based conflicts or even, as some observers have suggested, with a "water war." Water is the scarce commodity in a region that is rich in oil, gas, and mineral resources. Most of the water comes from two rivers, the Syr Darya and the Amu Darya. These feed the Aral Sea, previously the fourth largest inland fresh (actually brackish) water reservoir in the world. These rivers and their tributaries, together, form the Aral Sea basin. Since the 1960s, the Aral Sea has shrunk rapidly in surface area and in volume of water, representing "one of the world's worst ecological disasters." Increased demand for water for irrigation and hydroelectric power by the competing newly independent states, both upstream and downstream, is a potential source of interstate and even interethnic conflict. The latter could occur in the densely populated Ferghana Valley, where various countries such as Kyrgyzstan, Tajikistan, and Uzbekistan share common borders.

scholarly journals The effect of a water dam on Lake Powidzkie and its vicinity

2018 ◽  
Vol 15 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Bogumił Michał Nowak ◽  
Mariusz Ptak
Keyword(s):  
Water Resources ◽  
Water Levels ◽  
Anthropogenic Factors ◽  
Water Reservoirs ◽  
Water Deficits ◽  
Natural Lakes ◽  
Excess Water ◽  
The World ◽  
The 1960S ◽  
Natural And Anthropogenic Factors

Abstract The paper presents an attempt to assess the effect of damming of lakes on water resources, based on the example of Lake Powidzkie (Central Poland) and its catchment. The region in which the analysed object is located has the greatest water deficits in Poland. The co-occurrence of unfavourable natural and anthropogenic factors contributed to a considerable reduction in the water resources retained in the lake. Particularly low water levels were recorded in the 1990s and in the first decade of the 21st century. The situation was not improved by a water dam constructed on the out-flow from the lake in the 1960s, due, among other things, to neglect in its exploitation. With regard to the modernisation of the dam in 2010 and the favourable hydrological situation in the winter of 2011, it was possible to retain the excess water and substantially reduce its outflow. The restoration of the lost water resources, and the hydrological benefits of this were still observable several years later. Problems related to water deficits are becoming increasingly common in many regions of the world. One solution to mitigate such a situation may be, among others, to dam natural lakes. This is simpler, cheaper, and less invasive for the environment than the construction of new water reservoirs.

Desertification and Re-Greening of the Sahel

2017 ◽  
Author(s):  
Rasmus Fensholt ◽  
Cheikh Mbow ◽  
Martin Brandt ◽  
Kjeld Rasmussen
Keyword(s):  
Human Activities ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Climatic Variability ◽  
Anthropogenic Factors ◽  
Land Resource ◽  
Positive Trend ◽  
Vegetation Greenness ◽  
Positive Effects ◽  
Semi Arid

In the past 50 years, human activities and climatic variability have caused major environmental changes in the semi-arid Sahelian zone and desertification/degradation of arable lands is of major concern for livelihoods and food security. In the wake of the Sahel droughts in the early 1970s and 1980s, the UN focused on the problem of desertification by organizing the UN Conference on Desertification (UNCOD) in Nairobi in 1976. This fuelled a significant increase in the often alarmist popular accounts of desertification as well as scientific efforts in providing an understanding of the mechanisms involved. The global interest in the subject led to the nomination of desertification as focal point for one of three international environmental conventions: the UN Convention to Combat Desertification (UNCCD), emerging from the Rio conference in 1992. This implied that substantial efforts were made to quantify the extent of desertification and to understand its causes. Desertification is a complex and multi-faceted phenomenon aggravating poverty that can be seen as both a cause and a consequence of land resource depletion. As reflected in its definition adopted by the UNCCD, desertification is “land degradation in arid, semi-arid[,] and dry sub-humid areas resulting from various factors, including climate variation and human activities” (UN, 1992). While desertification was seen as a phenomenon of relevance to drylands globally, the Sahel-Sudan region remained a region of specific interest and a significant amount of scientific efforts have been invested to provide an empirically supported understanding of both climatic and anthropogenic factors involved. Despite decades of intensive research on human–environmental systems in the Sahel, there is no overall consensus about the severity of desertification and the scientific literature is characterized by a range of conflicting observations and interpretations of the environmental conditions in the region. Earth Observation (EO) studies generally show a positive trend in rainfall and vegetation greenness over the last decades for the majority of the Sahel and this has been interpreted as an increase in biomass and contradicts narratives of a vicious cycle of widespread degradation caused by human overuse and climate change. Even though an increase in vegetation greenness, as observed from EO data, can be confirmed by ground observations, long-term assessments of biodiversity at finer spatial scales highlight a negative trend in species diversity in several studies and overall it remains unclear if the observed positive trends provide an environmental improvement with positive effects on people’s livelihood.

MOSAICITY OF THE VEGETATION COVER OF THE KOCHUBEY BIOSPHERE STATION PASTURES

1970 ◽  
pp. 40-42
Author(s):  
М. А. Babaeva ◽  
S. V. Osipova
Keyword(s):  
Plant Species ◽  
Vegetation Cover ◽  
Cynodon Dactylon ◽  
Plant Cover ◽  
Avena Fatua ◽  
Living Environment ◽  
Anthropogenic Factors ◽  
Indigenous Species ◽  
Fodder Plants ◽  
Falcaria Vulgaris

The regularities of changes in the resistance of different groups of fodder plants to adverse conditions were studied. This is due to the physiological properties that allow them to overcome the harmful effects of the environment. As a result of research species - plant groups with great adaptive potential to the harsh continental semi-desert conditions were identified. Monitoring observation and experimental studies showed too thin vegetation cover as a mosaic, consisting of perennial xerophytic herbs and semishrubs, sod grasses, saltwort and wormwood, as well as ephemera and ephemeroids under the same environmental conditions, depending on various climatic and anthropogenic factors. This is due to the inability or instability of plant species to aggressive living environment. It results in horizontal heterogeneity of the grass stand, division into smaller structures, and mosaic in the vegetation cover of the Kochubey biosphere station. The relative resistance to moderate stress was identified in the following species from fodder plants Agropyron cristatum, A. desertorum, Festuca valesiaca, Cynodon dactylon, Avena fatua; as for strong increasing their abundance these are poorly eaten plant species Artemisia taurica, Atriplex tatarica, Falcaria vulgaris, Veronica arvensis, Arabidopsis thaliana and other. On the site with an increasing pressure in the herbage of phytocenoses the number of xerophytes of ruderal species increases and the spatial structure of the vegetation cover is simplified. In plant communities indigenous species are replaced by adventive plant species. The mosaic of the plant cover of phytocenoses arises due to the uneven distribution in the space of environmental formation, i.e. an edificatory: Salsola orientalis, S. dendroides, Avena fatua, Cynodon dactylon, Artemisia taurica, A. lercheanum, Xanthium spinosum, Carex pachystyli, under which the remaining components of the community adapt. Based on the phytocenotic indicators of pasture phytocenoses it can be concluded that the vegetation cover is in the stage of ecological stress and a decrease in the share of fodder crops and an increase in the number of herbs indicates this fact.

scholarly journals The effects of ENSO, climate change and human activities on the water level of Lake Toba, Indonesia: a critical literature review

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hendri Irwandi ◽  
Mohammad Syamsu Rosid ◽  
Terry Mart
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Human Activities ◽  
Southern Oscillation ◽  
Climatic Conditions ◽  
Water Levels ◽  
Dominant Factor ◽  
Climate Projections ◽  
Continuous Increase ◽  
The Future

AbstractThis research quantitatively and qualitatively analyzes the factors responsible for the water level variations in Lake Toba, North Sumatra Province, Indonesia. According to several studies carried out from 1993 to 2020, changes in the water level were associated with climate variability, climate change, and human activities. Furthermore, these studies stated that reduced rainfall during the rainy season due to the El Niño Southern Oscillation (ENSO) and the continuous increase in the maximum and average temperatures were some of the effects of climate change in the Lake Toba catchment area. Additionally, human interventions such as industrial activities, population growth, and damage to the surrounding environment of the Lake Toba watershed had significant impacts in terms of decreasing the water level. However, these studies were unable to determine the factor that had the most significant effect, although studies on other lakes worldwide have shown these factors are the main causes of fluctuations or decreases in water levels. A simulation study of Lake Toba's water balance showed the possibility of having a water surplus until the mid-twenty-first century. The input discharge was predicted to be greater than the output; therefore, Lake Toba could be optimized without affecting the future water level. However, the climate projections depicted a different situation, with scenarios predicting the possibility of extreme climate anomalies, demonstrating drier climatic conditions in the future. This review concludes that it is necessary to conduct an in-depth, comprehensive, and systematic study to identify the most dominant factor among the three that is causing the decrease in the Lake Toba water level and to describe the future projected water level.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

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