乌兰布和沙漠不同下垫面冬季沙尘通量

Winter Sand-dust Flux over Different Underlying Surfaces in the Ulan Buh Desert

为揭示乌兰布和沙漠不同下垫面冬季沙尘通量的垂直分布,在野外实地监测的基础上对乌兰布和沙漠3种下垫面冬季输沙量进行测量分析。结果表明：近地表0-100cm高度内冬季输沙量流动沙丘〉梭梭固定沙丘〉白刺半固定沙丘。各下垫面输沙量随高度呈下降趋势,流动沙丘、白刺半固定沙丘、梭梭固定沙丘符合幂函数分布,流动沙丘、梭梭固定沙丘输沙量集中于0-20cm高度,白刺半固定沙丘集中于0-40cm高度。风沙流幂函数通量系数a、b与粒径〈0.1 mm和粒径〉0.5 mm颗粒含量负相关,与粒径0.1-0.25 mm颗粒含量正相关,与粒径0.25-0.5mm颗粒含量不相关。沙粒跃移高度在流动沙丘、白刺半固定沙丘和梭梭固定沙丘分别集中于0-3.59、0-4.33和0-2.36cm;跃移高度与粒径〈0.05 mm和0.1-0.5 mm颗粒含量正相关,尤其与粒径0.1-0.25mm颗粒含量呈指数函数正相关,与粒径0.05-0.1mm及〉0.5mm颗粒含量无明显相关性。乌兰布和沙漠流动沙丘在冬季仍具有较大的侵蚀状态,白刺半固定沙丘处于弱风蚀状态,梭梭固定沙丘处于堆积状态,造成地表积沙。在冬季,梭梭固定沙丘仍然发挥着防风固沙的能力,成为冬季固定风沙的重要防线。

In order to reveal the vertical distribution of dust over different underlying surfaces in the Ulan Buh Desert in winter, the sediment discharge of 3 kinds of underlying surfaces were analyzed based on the actual monitoring data in winter. The total sediment discharge of 0-100 cm height in winter was mobile dune〉 fixed dune〉semi-fixed sand dune. The sediment discharge over 3 kinds of underlying surfaces all decreased with height and conformed to power function distribution. The sediment discharges over mobile dune, fixed dune were concentrated in 0-20 cm height and the sediment discharge over semi-fixed sand dune was mainly concentrated in 0-40 cm height. The coefficients a and b was negatively correlated with the concentration of 〉0. 1 mm particles and 〉0. 5 mm particles, and was positively correlated with the con- centration of 0.1-0.25 mm particles, and no correlation with the concentration of 0. 25-0. 5 mm particles. The saltation heights over mobile dune, fixed dune and semi-fixed sand dune were 3.59 cm, 2.36 cm and 4. 33 cm, respectively. There was a positive correlation between the saltation height and the concentrations of 〈0.05 mm and 0. 1-0. 5 mm particles, especially there was an exponential function relationship with the concentrations of 0. 1-0. 25 mm particles, but there was no significant relationship with the concentrations of 0.05-0.1 mm and 〉0.5 mm particles. The mobile dune in the Ulan Buh Desert was still in serious ero- sion in winter, and semi-fixed sand dune was basically stable, and fixed dune was in the accumulation state. Fixed dune was still play a role in sand fixation in winter.