筛分时间和投加量对沙漠沙干筛分析结果有着直接的影响,但目前对此鲜有报导。本文研究筛分时间(1~17 min)和投加量(20~100 g)对沙漠细沙筛分效果的影响。结果表明:在干筛分析过程中,20 g投加量时筛分效果在3 min达到稳定,而投加量在30~100 g时约在9 min达到稳定,意味着沙漠样品筛分需要的最短筛分时间与样品投加量有关。光学显微镜检测表明,干筛筛分的沙粒样品仍有11%~30%粗颗粒和1%~4%的细颗粒存在,此混杂比例具体因沙粒粒级而异。颗粒形状等因素造成了干筛筛分法与光学显微镜分析法的差异。
It is doubtless that sieving duration and sample weight can affect dry sieve analysis. However, the effect seldom had been reported. This paper is to understand the effect under different sifting duration (1-17 min) and weight (20-100 g). It indicates that the minimal sieving duration to separate effectively from different size particles is 3 minutes for 20 g samples and 9 minutes for 30-100 g samples. Uniform sand particles sieved dryly has 1%-4% of finer particles and 11%-30% of coarser particles in terms of microscopy method, indicating result of sieving method are less than that of microscopy method due to irregular shape of sand particles.
[1] Bagnold.The Physics of Blown Sand and Desert Dunes[M].London,UK:Methuen,1941:65-70.
[2] Marticorena B,Berganmetti G.Modeling the atmospheric dust cycle:1.Design of a soil-derived dust emission scheme[J].Journal of Geophysical Research,1995,100(D8):16415-16430.
[3] Shao Y.A model for mineral dust emission[J].Journal of Geophysical Research,2001,106(D17):20239-20254.
[4] Dong Z B,Liu X P,Wang H T,et al.Aeolian sand transport:wind tunnel model[J].Sedimentary Geology,2003,161(1/2):71-83.
[5] Mei F M,Zhang X Y,Lu H Y,et al.Characterization of MASDs of surface soils in north China and its influence on estimating dust emission[J].Chinese Science Bulletin,2004,49(20):2169-2175.
[6] 朱震达,陈治平,吴正,等.塔克拉玛干沙漠风沙地貌研究[M].北京:科学出版社,1981:8-18.
[7] 哈斯,王贵勇.腾格里沙漠东南缘横向沙丘粒度变化及其与坡面形态的关系[J].中国沙漠,1996,16(3):216-221.
[8] 钱亦兵,周兴佳,吴兆宁.准噶尔盆地沙物质粒度特征研究[J].干旱区研究,2000,17(2):34-41.
[9] Wang X M,Dong Z B,Zhang J W,et al.Grain size characteristics of dune sands in the central Taklimakan Sand Sea[J].Sedimentary Geology,2003,161(1/2):1-14.
[10] 李智佩,岳乐平,薛祥熙,等.毛乌素沙地东南缘不同地质成因类型土地沙漠化粒度分布特征及其地质意义[J].沉积学报,2006,24(2):267-276.
[11] 何清,杨兴华,霍文,等.库姆塔格沙漠粒度分布特征及环境意义[J].中国沙漠,2009,29(1):18-23.
[12] 张正偲,董治宝.土壤风蚀对表层土壤粒度特征的影响[J].干旱区资源与环境,2012,26(12):86-89.
[13] 张号,张克存,安志山,等.敦煌月牙泉景区沙丘粒度特征[J].中国沙漠,2014,34(3):645-649.
[14] 李超,董治宝,崔徐甲.腾格里沙漠东南缘不同发育阶段横向沙丘粒度分布特征[J].中国沙漠,2015,35(1):129-135.
[15] Chatenet B,Marticorena B,Gomes L,et al.Assessing the microped size distrbutions of desert soils erodible by wind[J].Seimentology,1996,43:901-911.
[16] Blott S J,Kenneth P.Particale size distributin analysis of sand-sized particles by laser diffraction:an experimental investigation of instrument sensitivity and the effects of particle shape[J].Sedimentology,2006,53:671-685.
[17] 梅凡民.中国北方典型区域风蚀粉尘释放的实验观测和数值模拟研究[M].西安:西北工业大学出版社,2013.
[18] Stefano C D,Ferro V,Mirabile S.Comparison between grain-size analyses using laser diffraction and sedimentation methods[J].Biosystems Enginerring,2010,106(2):205-215.