毛乌素沙地典型下垫面粉尘释放过程观测与模拟

Dust has an important influence on geochemical cycle, climate change and human health, etc. Dust emission process affected by a variety of factors of the underlying surfaces is the premise of dust transport, therefore strengthening the field observation and optimizing dust emission model has great significance for dust emission research. Mu Us Sandy Land is not only an important source region of dust emission in northern China, but also the key area of the Beijing-Tianjin-Hebei Sand Source Control Project. The project intends to choose the typical underlying surfaces, such as fixed, semi-fixed and mobile sandy land in Mu Us Sandy Land as objects of study, to analyze the dust content of surface soil and reveal the spatial distribution of dust emission potential in Mu Us Sandy Land. On the basis of the simultaneous observation for the wind speed, sand/dust flux and soil moisture,etc. in the established Dust Emission Observation Field, the dynamic variation characteristics of aerodynamic parameters, the horizontal saltation flux and the vertical dust emission flux would be analyzed to clarify the driving mechanisms of dust emission in the Mu Us Sandy Land. Compared the simulated data by DPM model with measured data on the horizontal saltation flux and the vertical dust emission flux in Dust Emission Observation Field, the model parameters would be tested and optimized. The results of the project would not only provide important scientific bases for quantitative estimation of regional dust emission, but also provide references for regional dust weather forecast and blown sand hazards control.

粉尘对地球化学循环、气候变化和人类健康等具有重要影响。粉尘释放过程是粉尘传输的前提，其受下垫面多种因素影响，加强野外观测和粉尘释放模型优化对于粉尘释放研究具有重要意义。毛乌素沙地是我国北方重要的沙尘释放源区，也是京津冀风沙源治理工程的重点地区。本项目拟以毛乌素沙地典型下垫面固定、半固定和流动沙地为研究对象，分析地表土壤粉尘含量，揭示毛乌素沙地粉尘释放潜力的空间分布规律；在建立的粉尘释放观测场内同步观测风速、沙尘通量和土壤水分等指标，分析空气动力学参数、跃移通量和粉尘释放通量的动态变化规律，阐明毛乌素沙地粉尘释放过程的驱动机制；采用DPM粉尘释放模型模拟观测场内的跃移通量和粉尘释放通量，与实测数据对比的基础上，检验和优化模型参数。本项目研究结果不仅可为区域粉尘释放定量估算提供重要科学依据，同时也可为区域沙尘天气预报及风沙灾害防治提供参考。

粉尘对地球化学循环、气候变化和人类健康等具有重要影响。对毛乌素沙地进行粉尘释放定量研究既是学科发展的需要，也是荒漠生态系统以及国家重大生态工程功能和价值评估的需要。本项目采用野外调查、定位观测、室内分析和数值模拟等方法，研究了毛乌素沙地典型下垫面（固定、半固定和流动沙地）的粉尘释放潜力以及释放过程的动态变化规律。研究结果表明：（1）毛乌素沙地典型下垫面不可蚀颗粒(>840 µm)含量很低，不足1%；毛乌素固定沙地的悬移组分(<100 μm)含量显著高于半固定沙地和流动沙地。（2）毛乌素沙地典型下垫面月平均风速、水平输沙通量和粉尘释放量都是春季最大。（3） 随着植被覆盖度的增大，毛乌素沙地的风速、水平输沙通量和粉尘释放量显著减少。大于5m/s风的频率：流动沙地(20.46%)>半固定沙地A (11.12%)>半固定沙地B(3.73%)>固定沙地(2.18%)。水平输沙通量和粉尘释放量大小依次为：流动沙地>半固定沙地A>半固定沙地B>固定沙地。本项目研究成果可为区域生态工程建设布局等提供重要参考。