风蚀作用对盐尘释放、输送过程的影响——以新疆艾比湖地区为例

Effects of wind erosion on the saltemission,transport process of salts:a case study of the area of Lake Ebinur,Xinjiang,China

艾比湖地区处于准噶尔盆地西部,发源于准噶尔西部山口的大风流决定了该区风蚀作用的发展。由于人类活动而引起的艾比湖的干枯变成了新松散物质来源,最终导致了该区沙尘-盐尘暴的加剧。从1950年以来,随着准噶尔西部山麓平原的开垦和河道三角洲灌溉农业的发展,新疆第一大盐水湖——艾比湖水域面积也逐渐缩小,干涸湖底和湖滨地区荒漠化程度加剧,已成为中国西北方区域沙尘-盐尘暴主要来源地。研究该区风力运输机制和风蚀作用对盐尘释放、输送过程的影响,分析降尘物中盐分的化学成分、总量及沙尘暴的年内发生率和强度机制等。研究结果表明,干涸盐土湖底和盐漠沙丘的风蚀对盐尘的释放、输送过程起到积极地作用,它的形成与盐尘的扩散与沉降有密切的关系。随着离干涸湖底距离越远,沙尘暴的发生率、强度及降尘量也下降;降尘量为600 g·m^(-2)·a^(-1)(湖近)到70 g·m^(-2)·a^(-1)(离湖水面距离为100～200 km),其中盐分总量为14～27g·m^(-2)·a^(-1);最大盐分含量可达为77 g·m^(-2)·a^(-1)。离湖越远,盐分的钙和硫酸盐成分越高,钠和氯化物成分越低。最后提出了对艾比湖湖区采取筑坝与隔离技术,分离出常年积水区和干涸湖底区,稳定艾比湖的水域面积,综合利用生物、化学、物理的防治技术,种植梭梭、柽柳、胡杨等耐盐灌、乔木树种,治理干涸湖底盐土风蚀的建议。

In the Ebinur region of Western Junggar in Xinjiang, strong wind flows from Ahaw Pass predetermine the widespread development of deflation processes. As a result of human-induced desiccation on Lake Ebinur, a new sources of the loose material - the dry lake bottom - has formed, which has led to intensification of dust storm in this region. Along with the development of virgin lands on the piedmont plain and on river deltas for irrigation farming since the 1950s ,the water area of Ebinur - as the largest salt lake in Xinjiang - has been reduced and the desertification of dry lake bed and lake beach have also been intensified,which is become the main sources of dust and salt -dust storm in China. In this paper, the dynamics of eolian transport, the effects of wind erosion on the salt transport process, annual dynamics of the frequency and intensity of dust storms have been studied and the amount, chemical composition of salts in the eolian material deposition in this area have also been analyzed. The frequency of dust storms and the intensity of dust and salt deposition regularly decrease with the increase of the distance from the dry lake bottom. The amount of dust deposition ranges from 600 （near the lake） to 70 （ 100 -200 km from the lake）g.m^-2.a^-1 The amount of salts precipitating with dust is about 14 -27 g . m^-2.a^-1. The maximum amount of salt deposition is 77 g . m^-2 .a^-1. The farther from the lake,the larger portion of sulfate and calcium and the smaller portion of chloride and sodium in the composition of salts. Lastly, construction of dikes and isolation technique are suggested to separate the dry lake bottom from the perennial water area in order to stabilize the water area of Lake Ebinur. To regulate the eolian transport of salts, some measures including integrated utilization of biology, chemistry and physics techniques, and planting salt tolerance trees such as Populus euphratica, Tamarix spp, Haloxylon ammodendron, are also suggested.