Areas Of Central Asia Research Articles

Assessment on Land-Water Resources Carrying Capacity of Countries in Central Asia from the Perspective of Self-Supplied Agricultural Products

Despite the declining hunger in Central Asia, food insecurity remains an important issue due to the dry climate. Taking Kazakhstan, Uzbekistan, Kyrgyzstan, Turkmenistan, and Tajikistan as examples, this study assesses their land-water resources carrying capacity in 1999, 2009, and 2018, on the premise that agricultural water and farmland are spatially matched based on the “buckets effect”, using the ecological footprint and water footprint methods. Results show the following: (1) the total farmland area in Central Asia is sufficient to achieve food self-sufficiency; the available farmland area is 2.45 times that of the farmland required for self-sufficiency in 1999, which decreased to 1.71 times in 2009, but slightly increased to 1.92 times in 2018. Specifically, Kazakhstan maintains a surplus of more than 15 × 106 ha in farmland, while the other 4 countries could not achieve self-sufficiency. (2) The water resources pressure rises; the available agricultural water resource (AAWR) in Central Asia is 3.07 times that of the water demand for agricultural irrigation (WDAI), and 3.06 times that of the water demand for irrigation and environmental purification (WDIEP) in 1999, which decreased to 1.69 times of WDAI and to 1.60 times of WDIEP in 2018. Tajikistan has the highest level of water surplus, followed by Kyrgyzstan and Kazakhstan. Turkmenistan and Uzbekistan do not have enough water to sustain agricultural production. (3) The trend of land-water resources carrying capacity declines in Central Asia. In 1999, 2009, and 2018, the land-water resources could support the population’s food demand in this region when only considering farmland matched with WDAI. However, the population carrying capacity deficit would emerge if we considered the matching farmland with WDIEP.

Risk assessment of soil erosion in Central Asia under global warming

Soil erosion is a threat to the ecological environment and human health. Climate change is closely related to soil erosion, and the ecological environment in Central Asia is sensitive to climate change. However, there is a lack of comprehensive risk assessments of the soil erosion by wind and water in Central Asia under climate change. This study used climate model data to simulate the spatiotemporal variation of wind and water erosion in Central Asia during the current period (1996–2015) and in the future with global warming of 1.5 °C and 2.0 °C (GW1.5 °C and GW2.0 °C, respectively) compared with the pre-industrial levels. The variations of exposure of population to soil erosion in the future were assessed. The results showed that the overall wind erosion in Central Asia is decreasing, but the area in which increasing wind erosion occurs will increase (2.6% under GW1.5 °C, and 8.6% under GW2.0 °C) compared with the current period. Water erosion in Central Asia is increasing, and the area in which increasing water erosion occurs will increase by 10.2% under GW1.5 °C, and 20.3% under GW2.0 °C. The central arid desert shrub area of Central Asia is the only area where both wind and water erosion increase significantly. Wind speed and precipitation are the main factors that contribute to wind and water erosion. Higher vegetation cover helps to reduce wind and water erosion. Under global warming, more population in Central Asia will be affected by soil erosion, primarily in the upper reaches of the Amu River and the lower reaches of the Syr River. This study should provide a scientific basis for formulating the ecological development plans in Central Asia to meet the United Nations Sustainable Development Goals (SDGs).

The Potential Global Climate Suitability of Kiwifruit Bacterial Canker Disease (Pseudomonas syringae pv. actinidiae (Psa)) Using Three Modelling Approaches: CLIMEX, Maxent and Multimodel Framework

In recent years, outbreaks of kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae, Psa) have caused huge economic losses to two major global kiwifruit producers, Italy and New Zealand. To evaluate the potential global risk areas of Psa, three modelling methods (MaxEnt, CLIMEX and a Multi-Model Framework, including Support Vector Machine or SVM) were used. Current global occurrence data for Psa were collected from different sources. The long-term climate data were sourced from WorldClim and CliMond websites. The model results were combined into a consensus model to identify the hotspots. The consensus model highlighted the areas where two or three models agreed on climate suitability for Psa. All three models agreed with respect to the climate suitability of areas where Psa is currently present and identified novel areas where Psa has not established yet. The SVM model predicted large areas in Central Asia, Australia, and Europe as more highly suitable compared to MaxEnt and CLIMEX. Annual mean temperature and annual precipitation contributed most to the MaxEnt prediction. Both MaxEnt and CLIMEX showed the probability of Psa establishment increased above 5 °C and decreased above 20 °C. The annual precipitation response curve showed that excessive rain (>1200 mm/y) constrains Psa establishment. Our modelling results will provide useful information for Psa management by highlighting the climatically susceptible areas where Psa has not established, such as the USA, Iran, Denmark, Belgium and especially South Africa, where kiwifruit has been planted commercially in recent years.

New records of leeches of the genus Limnatis (Hirudinea, Praobdellidae) from the South Caucasus and Central Asia: phylogenetic relationships of Eurasian and African populations

Leeches of the genus Limnatis Moquin–Tandon, 1827 infest mucous membranes of various mammals, including humans and domestic ungulates. The type species of the genus L. nilotica (Savigny, 1822) was initially thought to occur throughout the Western Palaearctic, from North Africa to the Middle East and Central Asia. It was later found that L. paluda (Tennent, 1859) is a widespread Western Asian species. However, the South Caucasus and vast areas of Central Asia have not been explored sufficiently in terms of leeches of the genus Limnatis. We recorded L. paluda from Azerbaijan and Uzbekistan for the first time. We also carried out the first molecular characterisation of L. nilotica herein. We found a deep genetic differentiation (8 %) between the Western Asian L. paluda and North African (Moroccan) L. nilotica based on their COI sequences. This finding corroborates a previous morphology–based hypothesis on their separate species assignments. The low genetic diversity of L. paluda is explained by the recent colonisation of arid landscapes of Western Asia.

The close-space luminescence dated loess record from SW Junggar Basin indicates persistent aridity during the last glacial-interglacial cycle in lowlands of Central Asia

Our understanding of how Central Asia evolves in response to climate change remains poorly constrained primarily due to the lack of sufficient paleoclimate records across different altitudinal zones with the adequate resolution for reconstructions. Using a 23.8 m thick loess sequence in the SW Junggar Basin, we establishe a robust chronology over the past ~150 kyr based on K-feldspar pIRIR techniques and Bacon age-depth modelling. To further track the paleoclimatic evolution of this part of Central Asia, this study documents changes in grain size, magnetic susceptibility, CaCO3 content, and sediment color. Together with previously reported loess records from the slopes and intermontane basins of the Tianshan Mountains, altitudinal and spatial variability in moisture changes during the last glacial-interglacial cycle are clarified in Central Asia. Our results indicate that loess in the SW Junggar Basin and northern slopes of Tianshan Mountains was mainly deposited during the Penultimate Glacial and Last Glacial periods. However, the deposition rates were relatively very slow deposition and/or deposited loess records have been entirely eroded possibly due to the deflation in the last interglacial and Holocene. The enhancement of the winter monsoon plays an important role in the rapid deposition of loess in Central Asia during glacial periods. Findings support that the continuous aridity prevailed in the lowlands of the Junggar Basin and the northern slope of Tianshan mountains during the last glacial-interglacial cycle, which is in opposition to the moist interglacial and dry glacial changes recorded in the higher altitude intermontane and mountain areas of the Tianshan Mountains. Limited Westerlies precipitation and high evaporation in lowland areas of Central Asia are responsible for prevailing aridity in these regions during interglacial periods.

Spatial-temporal characteristics of ecosystem health in Central Asia

Land-use/land-cover change in Central Asia has led to ecological disasters such as draining of the Aral Sea, salinization, desertification that ultimately affect the ecosystem's health. However, only a few studies have systematically assessed the spatial-temporal characteristics of ecosystem health in Central Asia using an integrated ecosystem assessment method. Therefore, this study aims to assess the ecosystem health of Central Asia using multi-source high-resolution data as the indicator and the integrated ecosystem vigor-ecosystem organization-ecosystem elasticity (V-O-E) model. The result showed that most of the areas in Central Asia are in a weak state of ecosystem vigor, ecosystem organization, ecosystem elasticity, and ecosystem health. The fragile state of the ecosystem health was highly due to the decreasing density of forest land, farmland, waterbody, and the increasing density of bare land and artificial land. The area of farmland gradually decreased, from 878639.08 km2 in 2000 to 719128.08 km2 in 2010 and 584251.36 km2 in 2017. The forest of Central Asia has been declining continuously from 161998.69 km2 in 2000 to 115343.96 km2 in 2010 to 81185.10 km2 in 2017 and has become spatially heterogeneous. Interestingly, the area of forest land in Xinjiang increased from 18216.14 km2 in 2000 to 20970.92 km2 in 2010 and 23098.12 km2 in 2017, although there was a decrease in the overall forest land in other countries of Central Asia; this shows that China's afforestation and reforestation policies during the last two decades had notable contributions to the ecosystem vigor and ecosystem elasticity in Xinjiang, which led to the increase in ecosystem health in Xinjiang. Hence, it is urgent to initiate integrated water management measures, limit the population growth and take adequate measures to enhance the techniques of farmland development to enhance the ecosystem health of Central Asia.

Impact of snow‐albedo feedback termination on terrestrial surface climate at midhigh latitudes: Sensitivity experiments with an atmospheric general circulation model

AbstractTo examine the effect of the snow‐albedo feedback (SAF) on the current surface climate across terrestrial regions at mid–high latitudes, we perform a series of idealized sensitivity experiments using an atmospheric general circulation model (AGCM), in which the snow albedo is assumed to be considerably smaller than that in the control experiment. When the snow albedo is reduced, the fall and spring surface air temperatures (SATs) in northern Eurasia are considerably higher than those in the control experiment. Particularly, the spring SAT at terrestrial high latitudes rises by more than 10°C, due to low snow albedo. Despite the small surface snow albedo during both fall and spring, the fall temperature difference between the two experiments is smaller than that during spring. The feedback with the hydrological effect, which accelerates snowmelt, is either nonexistent or weak during periods of seasonally low air temperatures. This result indicates that the hydrological effect significantly influences the SAF, and different magnitudes of the hydrological effect including cloud differences are a possible source of SAF uncertainty between models. The radiative albedo effect also impacts the evolution of the snow area in central Asia and eastern Europe through changes in lateral water vapour transport. Furthermore, the experiments indicate that the cooling effect of snow on land is necessary for the strength of the Siberian High and the pattern of Arctic Oscillation, suggesting that snow cover may also significantly extend the duration of Arctic Oscillation effects.

Climate Change Decreased Net Ecosystem Productivity in the Arid Region of Central Asia

Numerous studies have confirmed that climate change leads to a decrease in the net ecosystem productivity (NEP) of terrestrial ecosystems and alters regional carbon source/sink patterns. However, the response mechanism of NEP to climate change in the arid regions of Central Asia remains unclear. Therefore, this study combined the Carnegie–Ames–Stanford approach (CASA) and empirical models to estimate the NEP in Central Asia and quantitatively evaluate the sensitivity of the NEP to climate factors. The results show that although the net primary productivity (NPP) in Central Asia exhibits an increasing trend, it is not significant. Soil heterotrophic respiration (RH) has increased significantly, while the NEP has decreased at a rate of 6.1 g C·m−2·10 a−1. Spatially, the regional distribution of the significant increase in RH is consistent with that of the significant decrease in the NEP, which is concentrated in western and southern Central Asia. Specifically, the NPP is more sensitive to precipitation than temperature, whereas RH and NEP are more sensitive to temperature than precipitation. The annual contribution rates of temperature and precipitation to the NEP are 28.79% and 23.23%, respectively. Additionally, drought has an important impact on the carbon source/sink in Central Asia. Drought intensified from 2001 to 2008, leading to a significant expansion of the carbon source area in Central Asia. Therefore, since the start of the 21st century, climate change has damaged the NEP of the Central Asian ecosystem. Varying degrees of warming under different climate scenarios will further aggravate the expansion of carbon source areas in Central Asia. An improved understanding of climate change impacts in Central Asia is critically required for sustainable development of the regional economy and protection of its natural environment. Our results provide a scientific reference for the construction of the Silk Road Economic Belt and global emissions reduction.

A Cross-Sectional Study of the Street Foods Purchased by Customers in Urban Areas of Central Asia.

This study aimed to describe street food purchases in cities from Central Asia, considering customers’ characteristics and the nutritional composition of the foods and beverages. Cross-sectional studies were conducted in 2016/2017 in Dushanbe (Tajikistan), Bishkek (Kyrgyzstan), Ashgabat (Turkmenistan) and Almaty (Kazakhstan). Direct observation was used to collect data on the purchases made by street food customers, selected by random and systematic sampling. Nutritional composition was estimated using data from chemical analyses, food composition tables or food labels. A total of 714 customers (56.6% females, 55.5% aged ≥35 years, 23.3% overweight/obese) were observed, who bought 852 foods and beverages, the most frequent being savoury pastries/snacks (23.2%), main dishes (19.0%), sweet pastries/confectionery (17.9%), tea/coffee (11.3%) and soft drinks/juices (9.8%). Fruit was the least purchased food (1.1%). Nearly one-third of customers purchased industrial food items (31.9%). The median energy content of a street food purchase was 529 kcal/serving. Saturated and trans-fat median contents were 4.7 g/serving and 0.36 g/serving (21.4% and 16.5% of maximum daily intake recommendations, respectively). Median sodium and potassium contents were 745 mg/serving (37.3% of maximum recommendation) and 304 mg/serving (8.7% of minimum recommendation), respectively. In general, the purchases observed presented high contents of energy, saturated-fat, trans-fat and sodium, and low levels of potassium. Policies towards the improvement of these urban food environments should be encouraged.

Monitoring land degradation and assessing its drivers to support sustainable development goal 15.3 in Central Asia

Land degradation has become one of the most critical environmental and socioeconomic issues in the world, particularly in Central Asia. Moreover, the realization of Land Degradation Neutrality (LDN) in Central Asia faces enormous challenges in achieving the global Sustainable Development Goal 15.3 (SDG 15.3). It is critical to monitor land degradation and assess its drivers in Central Asia. In this study, an Optimal Land Degradation Index (OLDI) was established as a new index for monitoring land degradation using a constrained optimization algorithm. The spatiotemporal characteristics of LDN were monitored in Central Asia. Further analysis explored the driving force of land degradation in different areas. The results showed that 7.22% and 15.33% of the total land area exhibited land improvement and land degradation, respectively. According to abrupt change analysis, mutation changes in the OLDI were observed in 2005, 2012 and 2015. At the subnational scale, most regions in Central Asia have not achieved the goal of LDN. The residual analysis highlighted the drivers of spatial differences in land degradation performance in Central Asia. Drought was the main driving force affecting land degradation by the compound effect of decreased precipitation and increased temperature on the Ustyurt Plateau, while 24.01% of the land degradation areas resulted from anthropogenic disturbances and were mainly distributed in the areas surrounding the Aral Sea. The results also indicated that 72.56% of the land improvement areas resulted from human activities and were mainly concentrated in the Balkhash Lake Delta and the Amudarya Delta. In Central Asia, the realization of SDG 15.3 by 2030 remains a severe challenge. Restoration measures should be prioritized in land degradation areas in Central Asia to implement the LDN initiative, especially around the Aral Sea.

The analysis of grassland carrying capacity and its impact factors in typical mountain areas in Central Asia—A case of Kyrgyzstan and Tajikistan

Grasslands are among the main important terrestrial ecosystems on the earth. Central Asia has the biggest grazing part in the world due to a favorable environmental condition for the development of livestock farming. Thus, the evaluation of the health and productivity of such an ecosystem is so pertinent. This study aims at analyzing the grassland capacity dynamics in Tajikistan (TJK) and Kyrgyzstan (KGZ) mountains using Geographic Information System (GIS) and Remote Sensing (RS) techniques. Initially, the mountain boundaries were derived using the United Nations Environment Programme World Conservation Monitoring Centre (UNEP/WCMC) classification. Different datasets were used to calculate the seasonal dynamics of grassland carrying capacity in different periods (2000, 2010 and 2015) and we analyzed their driving factors. The main results showed that: (1) The mountainous area accounts for 89% and 91% in KGZ and TJK, respectively. (2) In both countries, the highest grassland carrying capacity was identified during the summer because of the high foraging value in relatively warm and humid conditions. From 2000 to 2015, the changing trend of mountain grassland carrying capacity in the two countries were similar in summer and autumn, both showed an increasing trend in summer, with 53.9% SU/hm2 in TJK and 5.2% SU/hm2 in KGZ; The grassland carrying capacity in autumn increased from 2000 to 2010 and then decreased from 2010 to 2015. In spring, changing trends showed that KGZ gradually decreased, while TJK showed a slightly increasing trend from 2000 to 2015. (3) From annual characteristics, the grassland capacity from 2000 to 2015 has increased by 43.9 SU/hm2 and 82.5 SU/hm2 in KGZ and TJK, respectively. The regions where the grassland carrying capacity increased in both countries were mainly located in the western and middle part of KGZ mountains while in TJK, the regions were identified in the southwest. (4)In 2010, the overgrazing ratio was 88.4% SU/hm2 in KGZ and 127.8% SU/hm2 in TJK. In both countries overgrazing region are mainly located in low elevation near the residential areas. (5) It was exhibited that the human-induced overgrazing superimposed the climate change influencing grassland carrying capacity in this study. Moreover, the results of this study are useful for leading regional livestock control mechanisms and environmental protection.

Impact of landscape dams on river water cycle in urban and peri-urban areas in the Shiyang River Basin: Evidence obtained from hydrogen and oxygen isotopes

To meet the needs of human recreation and provide community amenities, landscape dams (i.e., water retaining structures for intercepting river water in cities and surrounding areas, which are mainly used to create an urban landscape environment) are built in urban and peri-urban areas worldwide. The construction of these dams, however, may adversely affect the local and regional water cycle. We collected water samples from 2015 to 2019 from different water bodies in urban and peri-urban areas traversing the middle and upper reaches of Shiyang River Basin in the arid area of Central Asia to analyze their isotopic characteristics. Meanwhile, field surveys as well as meteorological, hydrological, and remote-sensing data were added to evaluate the hydrologic effects of urban landscape dams on a watershed scale in an arid region with scarce water resources and fragile ecosystems. Isotopic values of landscape water were more enriched than that of natural river. The result of the evaporation loss ratio showed that the landscape water was 0–5% higher. Moreover, the cumulative effect of multiple landscape dams leads to a great loss of water resources in arid areas. The study also demonstrated that evaporation is a vital factor in causing change in the isotope composition of the landscape water in the Shiyang River Basin. The interaction between surface water and groundwater was frequent within the landscape dam area wherein groundwater was mainly recharged by surface water leakage. Sufficient attention should be given to the evaporation, leakage, local precipitation, and groundwater changes caused by the impoundment of landscape dams. Thus, the potentially adverse effects of urban landscape dams in arid regions should be highly considered in long-term water-resources sustainability planning.

UNDERGROUND RUNOFF AS THE MAIN GEOHAZARDS IN THE MOUNTAINOUS REGIONS OF THE POST-SOVIET PART OF CENTRAL ASIA

The purpose of this article is to present the results of a study of the mutual influence of groundwater flow and results of human activities in the upland and lowland areas of Central Asia. The need for research was determined by the serious consequences of anthropogenic activities, which in recent years have required the inclusion of these tasks in the category of national security problems of the Central Asian States. Such tasks include, first of all, the extensive use of existing water resources in the Syrdarya and Amu Darya river basins, which was reflected in the well – known tragedy of the Aral Sea, the pollution of water resources during peaceful nuclear weapons tests, which negatively affected the state of the environment in East Kazakhstan, in addition-in the irrational use of water resources, including groundwater, on irrigated lands in Central Asia. These and other factors have determined the need to develop capabilities for predicting the state of both the aquatic environment and the influencing factors of human activity themselves. The solution of the problem presented in this article is based on the new fundamental scientific concepts developed by the authors, their own and attracted material of the results and is expressed in the proposed specific solutions.

Sino-Russia Strategic Partnership: The Case Study of Shanghai Cooperation Organization(SCO)

Since the dissolutionof Soviet Union, theUS and its Western allies have dominated the globalaffairs through numerous political and economic organizations. In the same token China and Russia have established close ties after the termination of Cold War to attain regional security so that to minimize the US penetration in the Central Asian region.Inthis article,the area of Central Asia has been taken as a case studyto demonstrate the China-Russia partnership through a multilateral organization;specifically the Shanghai Cooperation Organization. Thisarticle discussesthe theoretical underpinnings of the Soft Balancing in the SCO. It furtherelaboratesthe Sino-Russian cooperation through SCO in terms of balancing the US preponderance. This paperevaluateshistoricalcompetition amongGreat Powersin Central Asian region,and furtherelaborates onthe formation of the Shanghai Cooperation Organization1. While this article argues that the main focusof SCO was strengthening regional security issues, fight against terrorism, ethnic separatism and religious extremism. Howeverit also aimed to counter the US influencein the region through multilateral organization.

Review on Some Features of the Chinese Jujube (Ziziphus jujuba Mill.)

The Chinese jujube (Ziziphus jujuba Mill.), originating from China, with a history of over 4000 years, is one of the major fruit crops cultivated in China and on important areas in Central Asia, India, Iran, the Middle East etc. The high resistances to drought, salty soils and similar climate to that of China recommend this fruit tree as a valuable crop, especially in the context of climate changes and extended desertification. Chinese jujube has a high tolerance to pests and disease, being suitable for organic farming. The lack of divulgative papers on jujube true nutritional, medicinal and economic value, makes it still unknown for the great part of Romanian and European consumers, intensive advertising campaign is needed. The aim of this review is to highlight the requirements of the Chinese jujube (Ziziphus jujuba Mill.) in regards to the soil, water, climate as well as its high nutritional and medicinal values.

Ground penetrating radar for soil-water measurement in a semi-arid climate in the Orkhon River basin, central Mongolia

In this paper, we present a velocity analysis technique using ground-penetrating radar (GPR) data to estimate near-surface soil-water content affected by topography and solar radiation on a mountain peak, mountain mid-slope, and alluvial plain sites in a semi-arid climate area in central Asia. By making precise measurements of reflected EM wave velocity, the water content in the near-surface soil was determined. The GPR experiments at several frequencies were carried out in two sequential phases (comprising common-offset and multi-offset methods) to obtain the soil-water content and illustrate the subsurface structure. We then tried to determine the relationship between near-surface moisture content and permafrost thawing. Therefore, we used several different methods including time-domain reflectometry and a resistivity survey. We also confirmed via the GPR data that vegetation cover indicates soil-water content in the near-surface soil. The results evaluated in this study provide meaningful information about soil water as well as subsurface structures. The GPR data acquired at the survey sites indicated a large range of near-surface water content due to the topography of the survey lines.

Travel time curves and isochron maps from the Borovoye digital archive for the Nevada and Semipalatinsk Nuclear Test Sites

The paper presents generalized parameters of digital seismograms of the Borovoye Geophysical Observatory (BRVK). The seismograms were obtained after reformatting the archive of the Institute of Geosphere Dynamics (IDG RAS). For this research, we consider looking at the most representative entries – underground nuclear explosions (UNE). The particular interest is the analysis of the P-wave travel times at the regional distances Δ≈5–7° and Δ≈89–91°. These deep paths cross the boundaries of the Earth crust, mantle and outer core. There are UNE digital records at the Semipalatinsk Test Site (ΔSTS ≈5.56–6.27°) and at the Nevada Test Site (ΔNTS≈89.77–90.15°). For this reason, we use UNEs from STS and NTS from 1967 to 1992. UNEs locations and magnitudes are taken from published open sources. The results for P-wave travel time curves on the BRVK – NTS and BRVK – STS paths and the isochron maps are obtained. The linear functions for travel time curves are defined by the linear regression. The resulting seismic travel time curves for P waves are compared to AK135. Because global one-dimensional seismic reference models are non-unique solution to regional seismic data, in terms of physical structure. The results help identify seismic wave velocities at the source-receiver travel paths and character of geologic media. Such physical models could significantly facilitate physical interpretation of seismic structures in the area of Central Asia (e.g. Tien Shan) and global.

Records of iodine isotopes (129I, 127I) in the Barkol peat bog from northwest China and their sources, transport and preservation

The research on geochemical behaviors of iodine is significant for deep understanding of the source and distribution of iodine on the earth. However, as one of the most important sources, the ocean emissions and relative transport pathways of iodine, as well as the preservation after deposition are still not well known, especially in the arid areas of central Asia. A peat sediment core collected nearby Barkol Lake from northwest China was analyzed for iodine isotopes (127I and 129I). The observed high 127I concentration in the top 2 cm indicated a significant accumulation of iodine in the surface oxic conditions due to the continuous sources of incompletely decomposed organic matter. Dissociation of iodine into pore waters occurred once the anoxic conditions established beneath the surface by a serial reduction reaction during the degradation of organic matter. The temporal variation of anthropogenic 129I in the peat sediment recorded its sources and transport pathways. Besides the global fallout 129I during late 1950s and early 1960s, the significantly increased air releases from the European nuclear fuel reprocessing plants during 1975–1997 and the increased marine discharges since 1990s contributed the major portion of 129I in the peat core. The major transport pathway of 129I from the Europe was through Westerlies following the re-emission of the marine discharged 129I to the atmosphere, indicating a clearly ocean emitted iodine in the concerned central Asia.

Records of hydrological change and environmental disasters in sediments from deep Lake Issyk‐Kul

AbstractIn the context of global warming, the mountainous areas of Central Asia are sensitive to climate and environmental changes and are highly vulnerable to natural disasters. Here, we use high‐resolution lacustrine grain‐size and geochemical records from Lake Issyk‐Kul to infer hydrological changes, environmental events, and their driving factors in the western Tianshan Mountains of Central Asia over the last 350 years. The regional hydrological and environmental changes can be divided into three phases. In stage I (1674–1860 AD), the values of total organic carbon (TOC), total nitrogen (TN) and magnetic susceptibility (MS) were high, and the element contents changed indistinctively, suggesting that lake water levels were relatively stable. In Stage II (1860–2000 AD), the TOC and TN contents increased, the MS values decreased, and the grain size changed markedly, suggesting that water levels fluctuated dramatically. In Stage III (2000–2013 AD), the coarse particle and migratory element contents increased dramatically, indicating that regional rainfall and runoff increased and that the water level rose. Studies have also shown that the synchronous increases in sedimentary coarse particles, TOC and migratory elements indicate multiple flood events. Extreme floods have been frequent and intense in recent years, which indicates that the climate is generally warming, which is in good agreement with tree ring data, ice core records and other sediment records in alpine regions. Additionally, the lake sediments recorded a seismic event in approximately 1910 AD, which was consistent with historical documentation. Comparative analysis of records suggests that the Atlantic Multidecadal Oscillation is one of the dominant factors driving climate and hydrological changes in the study area. Climate change, combined with natural disasters (e.g., earthquakes) and anthropogenic activities, is generating extreme floods and variations in hydrological patterns in the mountain basin. These findings can provide crucial information about sedimentary physicochemical clues for tracking past hydrological and environmental conditions and contribute to a better understanding of hydrological processes and driving factors in the mountainous areas of Central Asia.

The Decrease in Lake Numbers and Areas in Central Asia Investigated Using a Landsat-Derived Water Dataset

Although Central Asia has a strong continental climate with a constant moisture deficit and low relative humidity, it is covered by thousands of lakes that are critical to the sustainability of ecosystems and human welfare in the region. Vulnerability to climate change and anthropogenic activities have contributed to dramatic inter-annual and seasonal changes of the lakes. In this study, we explored the high spatio–temporal dynamics of the lakes of Central Asia using the terraPulse™ monthly Landsat-derived surface water extent dataset from 2000 to 2015 and the HydroLAKES dataset. The results identified 9493 lakes and significant linear decreasing trends were identified for both the number (rate: −85 lakes/year, R2: 0.69) and area (rate: −1314.1 km2/year, R2: 0.84) of the lakes in Central Asia between 2000 and 2015. The decrease rate in lake area accounted for 1.41% of the total lake area. About 75% of the investigated lakes (7142 lakes), mainly located in the Kazakh steppe (especially in the north) and the Badghyz and Karabil semi-desert terrestrial ecological zones, experienced a decrease in the water area. Lakes with increasing water area were mainly distributed in the Northern Tibetan Plateau–Kunlun Mountains alpine desert and Qaidam Basin semi-desert zones in the east-south corner of Central Asia. The possible driving factors of lake decreases in Central Asia were explored for the Aral Sea and Tengiz Lake on yearly and monthly time scales. The Aral Sea showed the greatest decrease in the summer months because of increased evaporation and massive irrigation, while the largest decrease for Tengiz Lake was observed in early spring and was linked to decreasing snowmelt.