中亚干旱区咸海的湖面变化及其环境效应

Lake surface change of the Aral Sea and its environmental effects in the arid region of the central asia

由于气候和人类活动的影响,近百年来咸海水位出现了明显的波动,湖泊面积波动幅度近6×10~4 km^2,由此产生了严重的区域生态环境问题。尤其是近50年来,随着流域人口增加、社会经济发展、工农业及生活用水造成的流域水资源匮乏,导致咸海面积快速萎缩,引起一系列区域环境问题,威胁当地居民的生存。咸海水位下降、面积萎缩主要引发了两个方面的生态环境效应:(1)绿洲的荒漠化。干涸的湖底直接成为荒地,形成新的沙源地;同时,区域地下水位下降,植被退化,草地沙化,加之风力从干涸湖底及临近沙漠区带来的风沙覆盖,形成新的沙漠带。改变的下垫面,影响湖泊对气候的调节功能,造成流域人居环境的恶化。(2)湖滨湿地的消失及湖水的咸化,使得湿地资源与渔业资源等周围居民赖以生存的经济来源消失,同时由于来自裸露湖底的污染尘暴影响,使得流域原有土地功能退化。另外,污染的空气与饮用水直接威胁当地居民的健康。

Due to the climate and human activities effects, the Aral Sea water level fluctuates with the scope of about 60 000 km2. Consequently, it brings some serious problems about the region ecological environment. Especially in the last 50 a, for the population explosion, social economic development and water resources shortage ascribing to the industrial and agricultural and domestic water consumption, the Aral Sea area is shrinking rapidly, which arouse some region environment effects and threaten aborigines＇ livings. Two environment effects come into being because of the Aral Sea water level declining and area shrinking, they are as follows ： （ 1 ） Oasis desertification. The dried lake floor was turned into barren and became a new sand cradle. Simultaneously, a new desert was formed owing to the water table descending, vegetation retrogression, grassplot desertification and the sand blown by wind from the dried lake floor and nearby desert. The changed underlying surface influences the lake adjusting climate functions which worsen the human dwelling environments. （2） Because of the lakefront and marsh vanishing and lake water salinization, the nearby inhabitants＇ pocketbooks disappeared such as marsh and fishery resources. As a result of the pollute dust devil from the uncovered lake floor, the former land function is degenerating. In addition, the pollute air and drinking water threaten the aborigines＇ health directly.