激光衍射法和吸管法分析黏性富铁土颗粒粒径分布的比较

激光衍射技术(Laser diffraction technique,简称LD法)近年来被认为是一种有效的分析土壤颗粒粒径分布(Particle size distribution,PSD)的手段。为检验LD法在黏粒含量高的富铁土上应用的可行性,用LD法和传统的吸管法实测了6个黏性富铁土剖面(黏粒含量>40%)不同层次土样的PSD数据,比较发现:LD法能够提供更多颗粒粒径级别,尤其是黏粒部分(<2μm)的PSD信息,且分析耗时短,效率高。但是LD法与吸管法测定的不同粒级土壤颗粒的含量存在一定的差异。两种方法相比,激光衍射法"低估"黏粒和"高估"粉粒,或者沉降法"高估"了黏粒和"低估"了粉粒。虽然在黏性富铁土的黏粒部分未发现两种方法的线性关系,但粉粒和砂粒分别存在显著的线性相关。供试土壤黏粒含量高且分布范围窄是导致上述差异的主要原因。经过模型转换后,LD法和吸管法PSD实测数据之间的误差明显降低,这说明LD法可以用于黏性土壤的PSD分析。但是LD法PSD测定结果尚不能直接用于目前基于沉降法的土壤质地三角图,需要一定的数据转换。应该尽快通过对各类代表性土壤进行系统化和规范化的对比研究,提高LD技术的可靠性和实用性,建立起基于LD技术的新的土壤质地三角图,以便进一步深化其在土壤科学上的应用。     

岷江上游干旱河谷土壤粒径分布分形维数特征

具有分形特征是土壤的客观属性之一,为了探讨分形维数与土壤性质之间的关系与影响因素。运用土壤体积粒径分布分维模型计算了岷江上游干旱河谷不同土地利用方式下土壤表层(0～20cm)161个样品的分形维数,分析了分形维数的空间变化特点及其与粒度组成、有机质和土壤养分之间的相关性。土壤粒径分布分形维数可以作为表征土壤结构和性质的重要指标。结果表明:不同土地利用方式下土壤的粒径分布具有不同的分形特征,分形维数在2.5011～2.7825之间,粉壤土>壤土>砂壤土,耕地大于灌林地。土壤颗粒体积分形维数与黏粒(<0.002mm)和粉粒(0.002～0.05mm)的体积百分含量以及土壤全钾含量呈极显著正相关关系,与砂粒(>0.05mm)的体积百分含量呈极显著负相关关系,而与土壤有机质,全氮,全磷,速效磷和速效钾含量的相关性未达到显著水平。研究结果可以为研究区植被恢复和土地利用开发提供一定的依据。     

松嫩平原西部典型盐生景观土壤分形维数及盐碱化特征

为探究松嫩平原西部典型盐生景观土壤颗粒粒度组成及分形特征与土壤盐碱化之间的关系,采用体积分形维数模型计算了6种典型盐生景观土壤表层0—30 cm颗粒组成及分形维数,结合相关分析法分析了土壤分形维数与质地、盐碱特征之间的相关性。结果表明:(1)6种典型盐生景观中农田土壤分形维数值最小(2.35),碱蓬群落土壤最大(2.61),分形维数均值为2.48,分形维数随盐生景观土壤碱化程度增加而增大。(2)土壤质地越粗,砂粒含量越高,分形维数值越小;土壤质地越细,黏粒和粉粒含量越高,分形维数越大。(3)分形维数与盐分含量呈显著正相关(r=0.87,P0.05),尤其与盐分组成中HCO_3~-含量呈极显著正相关(r=0.89,P0.01),与养分中总磷含量呈极显著正相关(r=0.90,P0.01)。(4)土壤颗粒组成中砂粒、粉粒和黏粒与盐分、HCO_3~-及总磷含量也存在极显著相关性。不同盐生景观土壤分形维数与土壤颗粒组成和土壤盐分之间存在显著的相关性,因此可以用分形维数来反映土壤质地和指示土壤盐碱化特征。     

沙柳沙障对沙丘土壤颗粒粒径及分形维数的影响

统计分析了库布齐沙漠流动沙丘、设置沙柳活沙障和死沙障沙丘的土壤颗粒粒径分布、分形维数及其与土壤砂粒(>0.05 mm)、粉粒(0.05~0.002 mm)和黏粒(<0.002 mm)含量的关系。结果表明:与流动沙丘相比,设置沙障沙丘的粉粒和黏粒含量增加,且随着土层的加深而表现为下降趋势,不同部位则均呈沙丘下部>上部>中部的趋势。土壤颗粒分形维数因设置沙障而呈增大趋势,且表现为活沙障沙丘>死沙障沙丘>流动沙丘;垂直分布上,设置沙障沙丘的土壤分形维数随土层加深而逐渐减小,而流动沙丘表现为表层与下层大而中层小的特征,沙丘不同部位的分形维数则均表现为沙丘下部>上部>中部。土壤颗粒分形维数大小与土壤质地的细粒化有一致的变化趋势,且与砂粒含量呈极显著负相关关系,而与黏粒含量、粉粒含量呈极显著正相关关系。<0.05 mm粒径物质含量的增加和>0.05 mm粒径物质含量的降低共同导致了土壤颗粒分形维数在设置沙障后的增大。     

干旱风沙区路域柠条灌丛林地土壤重金属分布及其与土壤分形维数的关系

为了解干旱风沙区路域柠条林地土壤重金属的分布特征,探究其与不同粒径土壤颗粒和土壤分形维数的相关关系,为公路旁柠条林地土壤污染评价提供参考。以青银高速旁人工柠条林地为研究样地,调查了距高速公路0,30,60,100,150,200m灌丛林下表层土壤重金属Pb,Cu,Cd,Zn含量,并对土壤重金属含量与土壤粒径分布及土壤分形维数进行了相关分析。结果表明:(1)0~200m,土壤重金属Pb,Cu,Cd,Zn变化曲线均呈"单峰"型,峰值分别出现在150,30,0,60m处。(2)随着距高速公路距离的增加,土壤黏粒含量呈上升趋势,而极细砂粒呈下降趋势;土壤分形维数呈缓慢上升趋势。(3)相关分析显示,土壤Cd和Zn在土壤黏粒中存在明显富集作用,而土壤Pb和Cu在各粒径颗粒中均无富集作用。土壤Pb,Cu,Cd,Zn与土壤分形维数间均未表现出相关性(p0.05),而土壤黏粒(r=0.71,p0.05)和极细砂粒(r=0.73,p0.05)与土壤分形维数间均表现出线性相关关系。研究表明,干旱风沙区路域柠条灌丛林不同种类土壤重金属空间分布变化较大,且存在阈值。土壤粒径较小的黏粒更容易吸附重金属,其分布特点对路域土壤重金属扩散范围的研究有重要的参考意义。并且,土壤分形维数变化能够反映该区土壤理化性状的变化特征,可以将其作为路域土壤结构、土壤退化恢复程度的一个定量指标。     

子午岭植被自然恢复过程中土壤颗粒分形特征

运用土壤分形理论,研究黄土高原子午岭土壤粒径和颗粒体积分形维数(Dv)随植被恢复年限的变化特征,以期为黄土高原植被恢复和水土保持建设提供科学指导。研究表明:(1)黏粒、粉粒、砂粒及Dv均在0~10 cm和10~20 cm两土层之间差异显著,在16 a和60 a两年限间差异显著;(2)Dv随土层变化较小(2.326~2.340),随年限变化较大(2.307~2.347),Dv整体符合正态分布u=2.33,δ=0.02;(3)Dv与黏粒和粉粒呈显著的正相关关系,与砂粒呈显著负相关关系;(4)Dv和(<0.05 mm)/(>0.05 mm)粒级比值可表征土壤水土流失的状况。     

长期定位施肥对潮土分形维数的影响

应用土壤颗粒的质量分布特征来描述其分形维数的大小,研究了长期施肥对分形维数的影响,并分析了分形维数发生变化的原因。结果表明:施肥改变了土壤颗粒的分形维数,其中施高量有机肥能显著增加土壤颗粒的分形维数,而且分形维数的变化与粘粒含量的变化,有机质含量的变化和阳离子交换量(CEC)的变化都呈现极显著的正相关性,说明施肥对土壤的主要性状产生了影响。这可能是由于施肥使粘粒含量等土壤的基本理化性状或者粘土矿物组成发生了变化,才导致了分形维数的变化。     

PLA平铺沙障对沙丘土壤颗粒分形特征的影响

采用室外调查与室内分析相结合的方法,统计分析了毛乌素沙地PLA沙障铺设5年后的土壤颗粒粒径组成、分形维数及其与土壤砂粒(0.05 mm)、粉粒(0.05~0.002 mm)和黏粒(0.002 mm)含量的之间的关系。结果表明:研究区沙物质颗粒主要以粒径大于0.05 mm的细沙、极细沙为主。设置PLA沙障后,导致沙丘中粗沙含量减少,黏粒物质增加。沙障规格对土壤分形维数的影响表现为规格越小,土壤分形维数越大。沙丘表层分形维数与砂粒含量(0.05 mm)呈极显著的负相关关系,而与黏粒含量呈极显著的正相关关系。该地区颗粒分形维数的临界粒径为0.05 mm粒径物质,低于0.05 mm的颗粒含量越多,分形维数越高,反之则越低。设置PLA沙障后,黏粒物质聚集和沙粒物质的降低共同导致分形维数的增加。     

风水两相侵蚀条件下流域泥沙粒径分布分形维数特征——以黄河上游内蒙古段西柳沟为例

[目的]研究在风水两相侵蚀条件下流域泥沙粒径分布分形维数特征,为风水两相侵蚀产沙和高含沙水流侵蚀产沙的治理等问题的研究提供理论和试验依据。[方法]选取位于黄河上游内蒙古段的西柳沟流域为例,采集沉积物表层样,利用激光粒度仪对43个样点的泥沙粒度组成进行分析,采用分形理论,结合方差分析以及K均值聚类法进行分析和研究。[结果](1)不同沉积环境下泥沙粒径分布分形维数不同,以水力侵蚀为主的丘陵沟壑区分形维数平均值最大,为2.48;以风力侵蚀为主的沙漠区分形维数平均值最小,为1.95。(2)对于西柳沟流域,泥沙颗粒组成中粒径在0.05mm以下的含量越高,粒径越离散,分维值越高;粒径在0.05~1mm之间的颗粒含量越高,分形维数越低;粒径在1mm以上的颗粒含量与分形维数关系不明显。相对来说,粉粒含量对于分形维数的影响大于黏粒含量。[结论]地貌条件主要影响的是河床样的泥沙粒径组成,产沙层土样的颗粒组成不受地貌条件的影响,河滩样的泥沙粒径组成受地貌条件和沉积环境的双重影响。     

荒漠-绿洲边缘区生态过渡带的土壤颗粒分形特征

通过实地采样和实验室分析,测定了黑河中游荒漠绿洲边缘区生态过渡带的土壤粒级分布、有机碳(SOC)、全氮(TN)、全磷(TP)、速效氮(AN)和速效磷(AP)的含量,并采用1993年杨培岭等提出的用粒径的重量分布代替数量分布的土壤分形模型,计算了土壤颗粒分形维数;最后利用统计分析法,研究了颗粒分形维数与土壤粒级分布及各养分指标的关系.结果表明:从荒漠边缘向绿洲延伸的过渡带,土壤中砂粒含量占绝对优势,粉粒居中,黏粒最少,采样区土壤质地较粗;土壤颗粒分形维数在2.105～2.609之间变动,处于极低水平,与土壤各养分指标具有相似的变化趋势,除靠近绿洲区存在一个"生态裂谷"外,整体呈上升趋势;利用相关分析法得出,土壤颗粒分形维数与砂粒含量呈显著负相关,与黏粉粒及各养分指标均呈显著的正相关;利用回归分析法进行定量分析,砂粒含量每增加1g/kg,颗粒分形维数D降低0.0019个单位;粉粒和黏粒含量每增加1g/kg,颗粒分形维数D分别增加0.002和0,023个单位,对土壤颗粒分形维数变化幅度的影响依次为黏粒>粉粒>砂粒,分形维数对黏粒含量的变化最为敏感.因此,可以将土壤颗粒分形维数作为衡量荒漠-绿洲边缘区土壤养分变化状况的指标之一,用于反映荒漠绿洲区土壤的退化状况.     

伏牛山区迎河小流域不同土地利用类型的土壤粒径分布特征

为探讨伏牛山区坡耕地土壤物理性能的退化特征,在河南省鲁山县迎河小流域,利用激光粒度仪和土壤分形模型,比较分析了4种土地利用类型的土壤粒径分布(PSD)及其分形特征.研究结果表明:1)土壤PSD简单分维(Dv)以乔木林地最高(2.658),坡耕地最低(2.489),多重分维(容量维D0、信息维D1、关联维D2)以乔木林地最高(0.941、0.926、0.91),坡耕地最低(0.927、0.899、0.849).不同分形参数均表现为:坡耕地＜灌草坡地和水平梯田＜乔木林地;2)土壤PSD的Dv、D0、D1和D2,与黏粒和粉粒体积分数显著正相关,与砂粒体积分数显著负相关.因此,利用土壤PSD简单分形和多重分形维数,可量化表征土壤质地的粗细程度和非均匀性质的差别;坡耕地土壤质地的粗粒化程度和非均匀性明显大于其他土地利用类型;土壤细粒(黏粒和粉粒)物质流失是坡耕地土壤质地粗粒化和非均匀程度增大的重要原因.     

土壤颗粒的分形特征及其应用

本文应用土壤颗粒的质量分布原理来描述土壤颗粒的分形特征。通过对10种土壤颗粒的机械组成进行分析,分别计算出它们的分形维数（D=2.489～2.896）,并分析了其与土壤质地之间的关系。同时对土壤颗粒分形维数与所对应土壤的幂函数型水分特征曲线的拟合分形维数进行比较分析,建立了二者之间的相关关系。结果表明:分形维数的大小反映了土壤质地中粘粒、粉粒和砂粒含量的变化,随粘粒含量的增多分形维数增大,随砂粒含量的增多分形维数减小;同时土壤颗粒分形维数与所对应的水分特征曲线的拟合分形维数呈现出良好的一致性,因而对所研究的土壤而言,可应用土壤颗粒的质量分形维数结合幂函数模型来估算土壤水分特性曲线。     

土壤孔隙质量分数维D_m二元图像分析及其影响因素研究

本文简要介绍了利用土壤切片的二元图像分析了土壤孔隙结构的质量分数维Dm 的方法 ,并研究比较了四类土壤类型的Dm 及其影响因素。结果表明Dm 可以较好地定量描述土壤孔隙的空间分布特征 ,Dm 与土壤孔隙面积、孔隙孔径分布、土壤深度以及土壤质地之间均具有一定的联系     

引入分维理论评价土壤对优势流的敏感性

Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil,aeolian sandy soil,percolating paddy soil and permeable paddy soil.The dyed soil profiles were then photographed and the photos were scanned into a computer.Edited with certain software,only the dyed areas were left on the profile photos,which indicted the preferential flow paths for water and solute transport.Fractal dimensions of the dye patterns were calculated according to Arnold‘s function.Soil particle size distribution was analyzed by pipette method.The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile.Based on the experiment results,the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.     

Determination of soil texture: Comparison of the sedimentation method and the laser‐diffraction analysis

Laser‐diffraction analysis (LDA) is a rapid automated method achieving highly resolved frequency distributions of particle sizes. Recently, LDA has come into use in environmental sciences. However, in the size range of silt and clay deviations from the particle‐size analysis with the standard pipette method, which is regarded as the reference method for soil‐texture classification, have been reported. Therefore, this study concentrates (1) on the verification of systematic relations between both methods using a series of soils of Lower Saxony (Germany) and (2) on the general applicability of the laser‐diffraction method to soil‐texture classification as well as (3) texture‐based estimates of air capacity, available field capacity, and permanent wilting point. The comparison of LDA with the pipette method demonstrated highly significant linear correlations in each of the particle‐size fractions from clay to coarse silt. The slope of regressions ranged from 0.4 with fine silt to 3.1 with clay. If the clay content derived from LDA was applied to texture classification, the resulting textural classes differed from the standard textural classes, except for purely sandy samples with a clay content of <5%. However, the linear‐regression model enabled an approach of the LDA‐based clay content to values produced with the standard pipette method. Using this transformation, a texture classification became practicable in many cases, but, despite of a high significance level between LDA and pipette method, still led to wrong textural classes in several cases. A comparison with regression models from other regions in Europe showed both similarities and discrepancies, even for similar substrates. Hence, the laser‐diffraction analysis cannot be used for the texture classification of soil samples without verification by the standard pipette method.     

植被覆盖和雨强对附着在沉积物上的养分流失, 泥沙颗粒组成及体积分形维数的影响

Vegetation and rainfall are two important factors affecting soil erosion and thus resulting in nutrient loss in the Chinese Loess Plateau.A field experiment was conducted to investigate the effects of rainfall intensities(60,100 and 140 mm h-1) and vegetation(Caragana korshinskii) coverages(0%,30% and 80%) on soil loss,nutrient loss,and the composition and volume fractal dimension of eroded sediment particles under simulated rainfall conditions.The results showed that vegetation cover,rainfall intensity and their interaction all had significant effects on sediment transport and the sedimentbound nutrient loss.Higher rainfall intensity and lower coverage led to higher sediment and nutrient losses.Positive linear relationships were observed between soil loss and nutrient loss.The treatments showed more significant effects on the enrichment ratio(ER) of nitrogen(ERN) than organic matter(EROM) and phosphorus(ERP).Compared with the original surface soil,the eroded sediment contained more fine particles.Under the same coverage,the clay content significantly decreased with increasing rainfall intensity.The ER of sediment-bound nutrients was positively correlated with that of clay,suggesting that the clay fraction was preferentially eroded and soil nutrients were mainly adsorbed onto or contained within this fraction.There were increments in the fractal dimension of the sediment particles compared to that of the original surface soil.Moreover,the fractal dimension was positively correlated with clay,silt,and sediment-bound OM,N,and P contents,whereas it was negatively correlated with sand content.This study demonstrated that fractal dimension analysis can be used to characterize differences in particle-size distribution and nutrient loss associated with soil erosion.     

不同耕作年限水稻土土壤颗粒的体积分形特征研究

应用基于土壤颗粒体积分布确定土壤颗粒大小分布分形维数的方法,对浙江慈溪耕作年限分别为50、100、500、700、1000和2000年的水稻土土壤颗粒体积分形特征进行了研究.结果表明:同基于土壤颗粒质量分布的分形维数相比,基于土壤颗粒体积分布的分形维数计算不需要密度假设,更具有合理性.不同年限水稻土的土壤颗粒大小分布能被体积分形模型显著拟合(p＜0.01).土壤颗粒体积分形维数与黏粒的体积百分含量之间呈显著正相关(p＜0.01),与粉粒和砂粒的体积百分含量之间呈显著负相关(p＜0.01),其中与黏粒含量关系最为密切.耕作年限对水稻土土壤颗粒的体积分形维数和分形模型的拟合度均有一定影响.与50 ～ 500年水稻土相比,700 ～ 2000年水稻土剖面中土壤颗粒体积分形维数的变异性和均值较高,但其拟合决定系数则较低;耕作年限会对水稻土剖面中黏粒的含量和分布产生影响,进而影响到剖面土壤的颗粒体积分形特征;对于同一质地类型的土壤,耕作年限越长,分形维数越高.     

土壤样本分形几何特征的图像分析方法

土壤水分的持留与水分和溶质的运移,在很大程度取决于土壤孔隙的几何性质,而用数字图像处理方法能够较准确地加以识别。本文采用面积法和周长法分别计算了土壤样本图像的孔隙分形维数和多重孔隙轮廓线分形维数,并分析了它们同土壤质地之间的关系。结果表明,土壤孔隙空间在一定尺度范围内才存在明显的分形特征,土壤质地越细(粘粒含量越高)分形维数越大。与周长法相比较,用面积法计算的孔隙分形维数对土壤质地更为敏感。     

The effect of organic matter on the difference between particle-size distribution data obtained by the sedimentometric and laser diffraction methods

Particle-size distribution in dispersed sediments, soils, atmospheric dust, and other natural objects is their fundamental characteristic. The methods of sedimentometry (the pipette method) and laser diffraction have been applied to study particle-size distribution in a typical chernozem of Kursk oblast from the Alekhin Central Chernozemic Reserve. The content of the clay fraction as determined by the method of laser diffraction is three to five times lower than the clay content determined by the traditional pipette method. One of the reasons for such a great difference in the results obtained by two different methods is related to the low density of the solid phase of the particles of soil organic matter that have the size corresponding to the fine and medium silt fractions. Owing to this, they fall into the category of the clay fraction during the traditional sedimentometric analysis. The initially water-stable aggregates of 0.25–0.5 mm in size are subjected to several stages of their breakdown under the impact of ultrasonic dispersion with the detachment of small particles from their surface layers. The remaining aggregates have different resistance to ultrasonic treatment. After the long-term ultrasonic dispersion, the most stable microaggregates still exist in the soil mass. These microaggregates may only be decomposed to elementary soil particles after the addition of sodium pyrophosphate.