艾比湖干涸湖底化学组成及盐尘的风运堆积

Chemical components and transport mechanics of wind-erodible playa sediments,Ebinur Lake,Xinjiang

选择亚洲中部典型干涸尾闾湖——艾比湖干涸湖底及其下风向约200km的范围为研究区,并把研究区分为干涸湖底风蚀区和盐尘扩散堆积区两个子区.通过对两子区连续多年野外实地观测、采样分析、定点试验等手段,研究了干涸湖底表层沉积物的化学组成、湖底风蚀动态和盐尘的扩散堆积规律.结果表明,艾比湖干涸湖底不同地表形态(结晶盐壳、盐-淤泥-黏土壳、风蚀堆积壳)间可溶性盐含量差异显著,盐类混合物中以硫酸盐和氯化物为主,二者基本占全部可溶性盐的90%,碳酸盐含量甚微.春秋两季是湖底风蚀和盐碱尘暴的高发期,盐分堆积动态与风期变化一致,春、秋两季大风期,降尘中盐通量最高;冬、夏两季降尘中盐通量较低.干涸湖底下风向盐尘的堆积强度以精河为中心分别向西北和东北方向递减,盐尘在风运过程中表现出显著的分异规律,硫酸盐比氯化物具有更远距离的迁移能力.

Severe salt dust storms in north-western Xinjiang became frequent with the desiccation of the Ebinur Lake, and caused severe ecological consequences. With the intention of reducing the dust, the chemical composition of some main soils/sediment surfaces in the primary dust production zone were examined and the transport of aqueous-soluble solutes in dust were investigated. Sulfate and chloride were main evaporite minerals in the 0-5cm layer of surface crusts on the lake bottom. The content of aqueous-soluble solutes in aeolian dust showed a significant interaction with dust trap location and time of collection. Wind erosion of the lake bed and salt dust storm occurred frequently in the spring and autumn; dust collectors on the near-dust sources area, such as Jinghe, generally contained significantly more aqueous-soluble solutes and had greater total flux of solutes, then decreased with distance downwind and time. Chloride was found to deposit earlier than sulfate.