大气降尘沉积对塔克拉玛干沙漠腹地土壤水盐运移的影响  

Effects of the grain size and thickness of dust deposits on soil water and salt movement in the hinterland of the Taklimakan Desert

作　　者：孙艳伟[1,2] 李生宇[1] 徐新文[1] 张建国[1,2] 李莹[1,2] 

机构地区：[1]中国科学院新疆生态与地理研究所,乌鲁木齐830011 [2]中国科学院研究生院,北京100049

出　　处：《应用生态学报》2009年第8期1905-1911,共7页Chinese Journal of Applied Ecology

基　　金：中国科学院西部行动计划项目(KZCX2-XB2-13);国家自然科学基金项目(40701019);新疆维吾尔自治区重大科技专项(200733144-3);塔里木油田公司科研项目(971008090016;971008090017);中国科学院西部博士项目(XBBS200813)资助

摘　　要：利用微型蒸渗仪(MLS)对不同粒级和不同厚度大气降尘沉积条件下塔克拉玛干沙漠腹地土壤水分蒸发和盐分运移进行了模拟试验.结果表明:不同粒级和不同厚度大气降尘沉积均对研究区土壤水分蒸发和盐分运移有显著影响;在相同的沉积厚度和相同的初始含水量条件下,细粒物质(粒径<0.063mm)沉积可促进土体蒸发、加速下层土体的干旱和盐分的表聚,而粗粒物质(粒径0.063～2mm)沉积则抑制了土壤水分蒸发、降低了深层土壤水分的损失和盐分的表聚;研究区土壤水分蒸发抑制效率在0.20mm粒径处出现拐点,粒径在0.063～0.20mm时,蒸发抑制效率随粒径增大而增大,当粒径>0.20mm时,蒸发抑制效率则随粒径增大而减小.在相同粒级和相同的初始含水量条件下,不同厚度大气降尘沉积对土壤水分蒸发具有抑制作用,且土壤水分蒸发抑制效率随着沉积厚度的增大而增大,蒸发抑制效率与沉积厚度呈对数关系;沉积厚度越大,盐分向表层积聚越困难.降尘的加入可能导致干旱荒漠区生态系统的不稳定.By using mcirolysimeter, a laboratory simulation experiment was conducted to study the effects of the grain size and thickness of dust deposits on the soil water evaporation and salt movement in the hinterland of the Taklimakan Desert. Under the same initial soil water content and deposition thickness condition, finer-textured （ 〈0. 063 mm） deposits promoted soil water evaporation, deeper soil desiccation, and surface soil salt accumulation, while coarse-textured （0. 063-2 mm） deposits inhibited soil water evaporation and decreased deeper soil water loss and surface soil salt accumulation. The inhibition effect of the grain size of dust deposits on soil water evaporation had an inflection point at the grain size 0. 20 mm, i. e. , increased with increasing grain size when the grain size was 0. 063-0. 20 mm but decreased with increasing grain size when the grain size was 〉 0. 20 mm. With the increasing thickness of dust deposits, its inhibition effect on soil water evaporation increased, and there existed a logarithmic relationship between the dust deposits thickness and water evaporation. Surface soil salt accumulation had a negative correlation with dust deposits thickness. In sum, the dust deposits in study area could affect the stability of arid desert ecosystem.

关 键 词：大气降尘 塔克拉玛干沙漠腹地 粒级 厚度 土壤水分蒸发 盐分运移 

分 类 号：X51[环境科学与工程—环境工程]