干涸湖床不同类型盐土地表净风吹蚀实验研究

以内蒙古东乌珠穆沁旗及浑善达克沙地区域干涸湖床3种不同形态的盐土原状土为对象,通过风洞模拟实验,研究了干涸湖床不同类型盐土地表的净风吹蚀速率。对比风洞实验测定结果发现,3种盐土净风吹蚀速率依次是:蓬松盐霜盐土(14.44 g·m^-2·min^-1)>普通盐土(1.00 g·m^-2·min^-1)>结皮盐土(0.42 g·m^-2·min^-1)。风蚀过程中,不同类型盐土的近地表物质输移主要集中分布在0~10 cm的高度范围内,初始运动中,实验盐土风蚀颗粒物质以就地滚动和近距离跃移为主。实验观测发现,随着风速的增大,更多、更大的表面物质会受到更强烈的撞击与磨蚀作用,形成较细小的粉尘物质释放于空中,因此,干旱区盐土地表是形成区域盐碱浮尘或含盐沙尘天气的重要物源。不同类型盐土近地表物质输移总量从大到小依次是:蓬松盐霜盐土(3.17 g)、结皮盐土(0.42 g)、普通盐土(0.35 g)。

Wind Erosion on Different Solonchaks in Dried Lake Bed

In this study,the soil samples of the typical solonchaks including meadow solonchak,puffy solonchak and crustal solonchak as well as the topsoil and undisturbed soil were collected from the dried lake beds in northeast Inner Mongolia.Through wind tunnel experiments,the wind erosion rates of different solonchak samples were revealed.The compared results of wind tunnel experiments revealed that the pure airflow rates were in an order of meadow solonchak(12 m·s^-1)>puffy solonchak(9 m·s-1)>crustal solonchak(8 m·s-1).The wind erosion rates were in an order of puffy solonchak(14.44 g·m^-2·min^-1)>meadow solonchak(1.00 g·m^-2·min^-1)>crustal solonchak(0.42 g·m^-2·min^-1).With the increase of wind velocity,the difference of wind erosion rates of different solonchaks became more significant.The wind velocity higher than 15 m·s^-1 was the main driving force for wind erosion in the dried lake beds.During the process of wind erosion,the sediments were mainly distributed within the height 0-10 cm from the ground.In the initial movement,the movement of eroded materials from saline soil was dominated by rolling and close-range saltation.Results showed that the sediment flux was increased with the increase of wind velocity.With the increase of wind speed,more and more dust particles subjected to a stronger impact and formed finer dust particles to release into the air.Therefore,the salt land surface in arid area was an important source of material to form a regional saline dust or salt dust weather.The transport flux of soil samples was ranked in an order of puffy solonchak(3.17 g)>crustal solonchak(0.42 g)>meadow solonchak(0.35 g).