艾比湖湿地退化对盐尘暴发生及运移路径的影响

Effect of salt dust storm migration pathways on degradation of Ebinur Lake Wetland

新疆艾比湖湿地内间歇性裸露的干涸湖底加重了周围区域的盐渍化程度,为盐尘暴的发生发展提供了粉尘物质来源。盐碱粉末在风力作用下以颗粒物的形式悬浮在空中并向周围扩散,严重危害周边区域的生态安全和社会经济发展。本文选择研究区三期遥感影像,结合同期野外实测大气降尘及地表土壤采样数据,剖析区域土壤盐渍化与盐尘暴发生作用机制,探讨艾比湖湿地退化引发的盐尘暴在传输、沉降过程中对源地及途经区域的生态环境的影响,进而对盐尘暴的运移路径进行模拟预测。有关成果对于揭示该区域独特的盐尘暴发生及作用机制问题具有重要作用。

The lake wetlands are a transition zone between aquatic and terrestrial ecosystems. They are also one of the most important environments that sustain human beings, especially in arid and semi-arid areas of Northwestern China. The lake wetland ecosystem not only serves as an important media reflecting the dynamics of the local natural processes and habitat, but also promotes the interaction between human beings and the nature to maintain a sustainable balance between the two. Salt dust storm and alkaline dust deposition are generally caused by lack of water as loose deposits, dry lake bed crust, salt and saline soil are blown and salt deposits are dispositioned due to wind erosion. The salt powder in the form of suspended particles in the air becomes a natural disaster accompanied with strong wind. In addition to saline, alkaline elements, it contains crystalline dry lakebed sediments, toxic chemicals, and harmful heavy metal particles, which threaten plant survival. The development process of alkaline dust storm not only contaminates the air, food, water, and other natural resources with a mix of bacteria, fungi, and other toxic and harmful substances, but it also destroys the grassland and crops, and causes various diseases in humans and livestock. Intermittently exposed lake bottom of dry lake in the Ebinur Lake region is the primary source for salt dust storms in the surrounding area. Saline powder suspends in the air and spreads in the form of particles with the wind, seriously endangering the ecological stability and socio-economic development of the surrounding area. The current study attempts to investigate the dust storm migration pathways and its environmental effects using three remote sensing images combined with synchronous field measurements of salt dust and surface soil samples with the Hybrid Single Particle Lagrangian Integrated Trajectory （HYSPLIT） model. We also explore the environmental changes caused by salt dust storms and their impacts on the settlement process of Ebinur Lake by simulating and predicting the migration pathways of salt dust storms. Combining atmospheric dust deposition and surface soil data as well as the westerly direction and airflow path, we simulated the transport trajectories of salt dust for about four months in Bortala Mongol Autonomous Prefecture of Xinjiang Uyghur Autonomous Region, China. The results indicate that： （1） the degree of soil salinization within the study area is uneven. The highest level of salinization occurs around the Ebinur Lake but gradually weakens towards the peripheral expansion areas; （2） the dynamics of saline land is closely related to the change in vegetation cover and water area and to human activity, which also has a significant impact on the evolution of soil salinization; （3） there are two different paths of salt dust storm, the north path starting from Bortala Mongol Autonomous Prefecture→Aletai→ Gansu →Inner Mongolia Mongolia→Heilongjiang and southeastern path from Bortala Mongol Autonomous Prefecture （Jinghe, Bole, Wenquan, and Alashankou）→Wusu→Kuitun→Uriimqi→Kurla→Turpan-→Kumul. Our results present important information regarding the occurrence and mechanism of salt and dust storms in arid and semi-arid regions.