哈尔滨沙尘沉降物物源敏感粒度组分的提取及来源分析

Obtainment of Grain-Size Populations Sensitive to Material Source Area of Sand-Dust Fallouts in Harbin City and Their Source Analysis

采用粒级—标准偏差算法对哈尔滨2006年3月10日沙尘沉降物进行了物源区敏感粒度组分的提取,获得各来源组分的粒级范围和含量,并进一步分析了不同粒级成因组分的来源。研究认为：1）19.2μm是哈尔滨2006年沙尘天气颗粒短期悬浮和长期悬浮之界限,而152.4μm是沙尘颗粒悬浮搬运的粒径上限。2）20μm作为粉尘物质短期悬浮颗粒与长期悬浮颗粒之界限具有普遍性,而悬浮载荷的粒径上限则与一定的风力条件和地表状况密切相关。3）沙尘沉降物包含4个物源区组分,粒径范围分别为：〈1μm（组分1）、1-19.2μm（组分2）、19.2-152.4μm（组分3）和〉152.4μm（组分4）。前2个组分属长期悬浮组分,其中组分1代表大气粉尘的本底值;组分2代表非本地源的远距离外源输入,可能与高空气流的搬运有关,包括甘肃和内蒙古在内的半干旱地区为哈尔滨沙尘提供了一定量的粉尘物质;组分3为短期悬浮组分,主要是区域内部沙尘天气产生,松散地表裸土是该组分的重要物源;组分4为跳跃或滚动组分,源于近源物质堆积,是就地起沙。4）哈尔滨2006年沙尘天气外源输入约占63.8%,近源和内源输入占36.2%。松散地表裸土的治理仍是哈尔滨防治沙尘天气的工作重点。

Grain-size analysis of sand-dust fallouts retrieved from Harbin City in 2006 was carried out using a Malvern 2000 grain-size analyzer.The grain-size populations sensitive to material source area was obtained according to variations in the grain-size standard deviation,grain-size classes scope and content of all source components was attained,and source of different grain-size classes populations was discussed.Major conclusions include：1） 19.2 μm is a limit of short-term and long-term suspension sand-dust weather particles in Harbin,and 152. 4μm is grain-size upper limit of suspended particles. 2） It is general that 20μm is regarded as limit of long-term suspension components and short-term suspension components, and however grain-size upper limit of suspension loads is in well relation to wind power condition and ground condition. 8） The sand-dust fallouts include four material source area populations：① 〈1μm,② 1-19.2μm,③ 19.2-152. 4μm,④ 〉152. 4μm. The former two components are the long-term suspension components, of which component ① represents the atmospheric dust background value, and of which component ② represents the long-range non-local sources of exogenous input,may be related to the transport of high-alti tude air currents, the semi-arid areas, including Gansu and Inner Mongolia,may offer Harbin sand dust a certain amount of dust material. Component ③ are short-term suspension components, mainly arising from intra-regional dust weather, the loose bare surface soil, including city construction soil and road bare soil,is the major material sources. Component ④ is jumping or rolling component,derived from the accumulation of near-source material, elevating sand on the spot. 4）Harbin sand dust weather in 2006 gives priority to outer-source input （about 63.8%）, and near-source and inner-source input amount to 36.2 %. The con trolling of the loose bare surface soil still is the work keystone of preventing sand-dust weather around Harbin area.