Identifying Seasonal and Diurnal Variations and the Most Frequently Impacted Zone of Aerosols in the Aral Sea Region.

With the desiccation of the Aral Sea, salt-alkali dust storms have increased in frequency and the surrounding environment has deteriorated. In order to increase our understanding of the characteristics and potential impact zone of atmospheric aerosols in the Aral Sea region, we evaluated seasonal and diurnal variation of aerosols and identified the zone most frequently impacted by aerosols from the Aral Sea region using CALIPSO data and the HYSPLIT model. The results showed that polluted dust and dust were the two most commonly observed aerosol subtypes in the Aral Sea region with the two accounting for over 75% of observed aerosols. Occurrence frequencies of polluted dust, clean continental, polluted continental/smoke, and elevated smoke showed obvious seasonal and diurnal variations, while occurrence frequency of dust only showed obvious seasonal variation. Vertically, the occurrence frequencies of all aerosol subtypes except dust showed significant diurnal variation at all levels. The thickness of polluted dust layers and dust layers exhibited same seasonal and diurnal variations with a value of more than 1.0 km year-round, and the layer thickness of clean continental and polluted continental/smoke shared the same seasonal and diurnal variation features. The zone most severely impacted by aerosols from the Aral Sea region, covering an area of approximately 2 million km2, was mainly distributed in the vicinity of the Aral Sea region, including western Kazakhstan, and most of Uzbekistan and Turkmenistan. The results provide direct support for positioning monitoring of aeolian dust deposition and human health protection in the Aral Sea region.

Agricultural impacts drive longitudinal variations of riverine water quality of the Aral Sea basin (Amu Darya and Syr Darya Rivers), Central Asia.

River ecosystems are under increasing stress in the background of global change and ever-growing anthropogenic impacts in Central Asia. However, available water quality data in this region are insufficient for a reliable assessment of the current status, which come as no surprise that the limited knowledge of regulating processes for further prediction of solute variations hinders the development of sustainable management strategies. Here, we analyzed a dataset of various water quality variables from two sampling campaigns in 2019 in the catchments of two major rivers in Central Asia-the Amu Darya and Syr Darya Rivers. Our results suggested high spatial heterogeneity of salinity and major ion components along the longitudinal directions in both river catchments, pointing to an increasing influence of human activities toward downstream areas. We linked the modeling outputs from the global nutrient model (IMAGE-GNM) to riverine nutrients to elucidate the effect of different natural and anthropogenic sources in dictating the longitudinal variations of the riverine nutrient concentrations (N and P). Diffuse nutrient loadings dominated the export flux into the rivers, whereas leaching and surface runoff constituted the major fractions for N and P, respectively. Discharge of agricultural irrigation water into the rivers was the major cause of the increases in nutrients and salinity. Given that the conditions in Central Asia are highly susceptible to climate change, our findings call for more efforts to establish holistic management of water quality.

Investigating and evaluating the dynamics of change in water resources of the Aydar-Arnasay Lake system in Uzbekistan.

The Aydar-Arnasay Lake System (AALS) is located in the middle of the Syrdarya River, to the south of the Chardara Reservoir, and in Jizakh and Navoi provinces of the Republic of Uzbekistan, adjacent to the low plain of South Mirzachul. Currently, the AALS has a significant impact on the regional ecosystem and socio-economic conditions of the region. Studying and evaluating the AALS hydrology, the water volume, surface area, and variability of water levels altogether play an important role in the development of fisheries and ecotourism in the region. However, in the past studies, the dynamic changes in the volume, area, and water levels of the AALS have not been investigated through up-to-the-date geo-information systems (GIS), requiring additional research to formulate a proper methodology considering the potential aspects of GIS. Therefore, this paper aims at analyzing the dynamics of changes in the water level, surface area, and water volume of the AALS by using GIS technologies within 1993-2017 years. During the period from 1993 to 2006, the water level and the surface area of the AALS steeply increased and remained stable with negligible positive and negative fluctuations in the rest of the experimental years. These findings were successfully tested and validated by ANOVA, indicating an exceptionally low F-significance of 0.0008. According to the AALS's water volume dynamics, we investigated here the role of two factors: anthropogenic-the outflow water discharge from the reservoir located in the neighboring country; and natural-the amount of perennial precipitation. Consequently, we ascertained that the role of precipitation as a natural driving factor in expansion is majorly less than the outflow water from the reservoir, despite having a gradual increase in the perennial precipitation trend. As we assume that the hydrological characteristics of the AALS are strongly dependent on air temperature and the amount of precipitation due to the extreme restriction of outflow water discharge from the reservoir, thus the establishment of proper GIS-tracking and monitoring methodology is recommended to early warn the potential minor changes which could become severe in the near future.