桂林岩溶区不同利用方式土壤粒径分布与活性有机碳的关系

为了解岩溶区土壤粒径分布与活性有机碳组分的关系,分别从岩溶区和碎屑岩区选取林地、灌草丛、果园三种主要土地利用类型,测定其土壤剖面的颗粒组成以及活性有机碳组分含量。结果表明,岩溶土壤与碎屑岩土壤粒径分布中,0.002 mm粒组含量最大,均超过25%,且土壤质地以黏土为主。岩溶土壤总有机碳剖面分布呈凸肚型,其含量在剖面10~30 cm处达到最大值;而碎屑岩土壤总有机碳含量随着剖面深度的加深呈下降趋势,其含量在剖面0~10 cm处为最大值。除岩溶林地外,其余剖面的微生物量碳含量均随土壤深度的加深而减小,在剖面深度0~10 cm处为最大值,在70~90 cm处为最小值。岩溶区土壤溶解有机碳含量在不同深度的差值较小;碎屑岩区溶解有机碳含量在0~10 cm处为最大值,在20~30 cm处为最小值。岩溶区溶解有机碳含量与0.02~0.002 mm粒组呈显著负相关关系(p0.05),与0.002 mm粒组呈显著正相关关系(p0.05);碎屑岩溶解有机碳含量与2~0.25 mm及0.25~0.05 mm粒组呈显著负相关关系(p0.05),与0.002 mm粒组呈显著正相关关系(p0.05)。在不同土地利用方式中,林地土壤微生物量碳及溶解有机碳含量最大,灌草丛土壤次之,果园土壤最小,且果园土壤0.002 mm粒组含量最小。     

A Study of Airborne Selected Metals and Particle Size Distribution in Relation to Climatic Variables and their Source Identification

Ten selected metals (Na, K, Fe, Zn, Pb, Mn, Cr, Co, Ni & Cd) were estimated in total suspended particulate (TSP) samples collected on glass fibre filters in urban Islamabad, Pakistan, from October 2002 to May 2003, using a high volume sampling technique. The wet digestion method (HNO₃/HClO₄) was used for metal analysis by the flame atomic absorption spectrophotometry (FAAS) method. Maximum mean contribution was noted for Na (1.949 μg m^?3), followed by K (0.900 μg m^?3), Zn (0.603 μg m^?3), Fe (0.584 μg m^?3) and Pb (0.214 μg m^?3). The particle size determination on % volume basis for four fractions (PM_{< 2.5}, PM_2.5–10, PM_10–100& PM_{> 100}) was also carried out. PM_10–100 were found to be the most abundant in the local atmosphere followed by PM_2.5–10, while the respirable fraction (PM_{< 2.5}) and giant fraction (PM_{> 100}) showed comparable and lower levels. The trace metals were found to be mainly associated with PM_{< 2.5} and PM_2.5–10. The influence of climatic variables on toxic trace metals and particle size fractions was also investigated statistically and it was revealed that temperature has a significant correlation with fine particle fractions and airborne trace metal levels. The source identification was carried out by Principal Component Analysis and Cluster Analysis. Four metal sources were identified: industrial (32.6%), soil-derived dust (21.9%), traffic/road dust (19.8%), and metallurgical/garbage incineration (12.4%). The metal levels were also compared with those reported for other parts around the world.     

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.     

艾比湖湿地不同盐渍化土壤粒度组成及可蚀性研究

为了研究内陆干旱区不同盐渍化土壤的粒径组成及其可蚀性的空间分布,在不同盐渍化程度上探讨其与土壤中盐分含量的相互关系,本研究以新疆维吾尔自治区艾比湖湿地为研究靶区,利用2015年5月获取的66个表层土壤样品,对土壤的粒度组成、含盐量、分形维数和可蚀性因子K值进行了研究。结果表明:样品中盐土占比达到59.09%,平均含盐量达131.59 g/kg,研究区内盐渍化现象既普遍又严重;土壤颗粒以粉粒和砂粒为主,随着盐渍化程度的加剧黏粒含量不断增加,砂粒含量则相反;土壤颗粒的分形维数D值介于2.14~2.60,平均值为2.45;随着盐渍化程度加剧,分形维数逐渐变大,K值也随之逐渐增大,盐土的K值最大达0.093;土壤可蚀性因子K值与含盐量的相关性较高(r=0.596**),在一定程度上可以说明,土壤的含盐量水平越高,K值越大,越容易被侵蚀。     

前处理方法对激光粒度仪测试碳酸盐岩红土粒度结果的影响

前处理方法的优化研究是促进激光粒度仪分析技术在南方红土区推广的关键环节。以黄土粒度前处理方法为基础,设定不同的H2O2、HCl和分散剂(Na PO3)6的加入剂量以及不同的反应温度和超声波震荡时间来处理采自云南高原程海地区海拔2000 m的碳酸盐岩红土样品,结果发现:(1)加入HCl处理会使激光粒度仪测量结果偏粗,不加HCl只加H2O2可以获得较细的粒度测量结果;(2)加(Na PO3)6分散剂后样品测试结果重现性较高,但粒度偏粗,当加入剂量超过5 ml(0.05 mol l-1)后加入剂量的多少对测试结果影响不大,未加(Na PO3)6的样品测试结果重现性差,但粒度总体偏细;(3)加热处理比未加热处理样品的粒度偏粗,加热不利于样品的分散;(4)经超声波震荡的样品较未震荡的样品颗粒分散程度高,但震荡时间超过2分钟后,增加震荡时间对分散结果影响不大。     

土壤颗粒分级过程中超声破碎和离心分离的条件选择

按照离心机SORVALL Legend RT的水平转子的尺寸,并根据斯托克斯公式对文献中已有的土壤颗粒分级方法中的离心时间重新设定。同时讨论了利用超声波进行土壤颗粒分散的使用条件,尤其应针对不同的土壤调整超声破碎仪的能量输入。用新优化的土壤颗粒分级方法对中国科学院沈阳生态试验站采集的棕壤进行了分级,其结果与吸管法所得结果基本一致,并且回收率能达到95%以上。     

Size Guide Number and Rosin–Rammler Approaches to describe Particle Size Distribution of Granular Organic-based Fertilisers

The physical properties of organic-based fertilisers are not well known. The main objective of this study was to evaluate the range of granule size distributions of organic-based fertilisers and compare five approaches used to describe their size distribution: (1) the size guide number N_SG and uniformity index; (2) the size range variation coefficient; (3) the uniformity coefficient; (4) the geometric standard deviation of the particle size diameter; and (5) the Rosin–Rammler function. Six mineral (MF), four bulk-blended organic-based (BOF), and ten compound organic-based fertilisers (COF) were studied. Standard N_SG boxes and Tyler sieves were used to measure their granule size distribution. The size guide number ranged from 200 to 246 for MF, from 204 to 216 for BOF and from 99 to 255 for COF. The uniformity index was higher for slow release MF and for COF with N_SG>210. All five distribution parameters separated the fertilisers into similar groups. The coefficient of uniformity was the least discriminating approach in grouping the fertilisers, while the geometric standard deviation and size range variation provided similar results and the Rosin–Rammler approach was the most discriminating. The N_SG and uniformity index were estimated with the Rosin–Rammler function. Comparisons between estimated and measured size guide numbers indicated that the Rosin–Rammler function performs better for MF and for spherical granule shapes. Differences between the uniformity index values were greater for BOF, COF, and for cylindrical-shaped granules. The Rosin–Rammler function was not accurate for homogeneous and binomial particle size distributions, or for cylindrical granule shapes. However, in all other cases, this function was more precise and presented many advantages over the other methods, including the fact that it covers the entire range of particle sizes and can be used to estimate other parameters.     

宁东能源工业基地表层土壤粒径分布、养分、重金属含量与大气降尘的关联性

[目的]研究宁东能源工业基地大气降尘携带的营养物质、重金属与土壤养分、重金属含量之间的关联性,为该区域的土壤利用和环境保护提供科学依据。[方法]本研究在宁东能源工业基地马莲台电厂主导风向下风向采集不同距离的表层土壤和大气降尘样品,分析土壤和降尘样品的粒径组成、分形维数以及6种重金属(Zn,Cu,Cd,Cr,Pb,Ni)的空间分布特征及其潜在生态风险;利用Pearson相关性分析法对表土与大气降尘中重金属含量的相关性进行探讨。[结果](1)宁东能源工业基地大气降尘的成分来源复杂,包括了自然源和人为源降尘。其中自然源降尘主要来自于境内沙尘,主要成分为石英、方解石、斜长石、绿泥石和高岭石等。人为源降尘则主要源自燃煤烟尘,主要成分涉及Ag,Cr,Pb,Co,Mn,As,Cu和二硫化硅以及多环芳烃化合物(PHAs)等。(2)大气降尘和表土的粒径分布曲线在不同距离上均呈非正态性及双峰和多峰分布,说明大气降尘和表土颗粒组成具有多源性。(3)大气降尘和表土综合潜在生态风险指数表明,距离污染源越远降尘中重金属的生态风险指数越大,而土壤中重金属的生态风险指数越小。Pearson相关分析分析表明,表土与大气降尘中Cr和Cu两种重金属元素具有一定的正相关性。(4)大气降尘携带的营养物质沉降到地表改变了土壤的养分供给,尤其是有机质的增加量最为显著。[结论]宁东能源工业基地大气降尘成分复杂,对土壤组成有显著影响,且增加了其潜在生态风险指数,尽管其颗粒粒径组成、分布、养分、重金属含量与大气降尘的关联性相对较弱,但其累积效应仍然值得关注。     

土壤及泥沙颗粒组成与养分流失的研究

利用自然降雨影响下的农田为试验样地,分析了降雨前后土壤颗粒组成与养分含量的变化,探讨了流失泥沙颗粒组成与养分的变化特征。结果表明,在降雨后,西瓜地与油菜地表土颗粒组成呈现粘粒与粉粒含量减少,砂粒含量相对增加的趋势;土壤养分含量都有不同程度的下降,其中水解氮与速效磷下降的幅度很大,西瓜地与油菜地水解氮降雨后降幅分别为9.67%和7.99%,速效磷的降幅分别为9.20%和8.76%;全氮养分降幅很小,西瓜地与油菜地分别为2.17%和1.54%;流失泥沙细小颗粒含量与养分含量随时间基本都呈降低的变化趋势,并且细小颗粒含量与携带流失的养分含量有显著甚至极显著的正相关性;流失泥沙具有富集粘粒和富集养分的特性,油菜地与西瓜地粘粒富集率分别为1.23和1.20,两样地全氮与速效磷的富集率都在1.3以上,而全磷和水解氮富集率基本处在1.1-1.3之间。     

Effect of Particle Size and Moisture Content on Viscosity of Fish Feed

A model was developed for the influence of particle size on the extrusion of a fish feed and the physical characteristics of the extrudates evaluated. The study was conducted using factorial experiments in a fractional replication design for four variables with three levels, and one‐third of the replicates (3⁴ factorial in 27 units) were examined in a laboratory extruder. The torque‐screw speed measurement was used to develop a viscosity model equation that considered different shear rates, product temperature, initial moisture content, and particle size. When particle size decreased, the apparent viscosity became smaller. The barrel pressure was important in producing extrudate with a uniform volume over the range of processing conditions tested because it had a strong correlation with the volumetric expansion. The material with lower moisture and larger particles caused the specific mechanical energy to increase. The viscosity model developed in this study can be applied to the development of large‐scale extrusion models that determine the effect of particle size on the feed material extrudates.     

Heavy Metal Content of Some Savanna Plant Species in Relation to Air Pollution

The Sb, Cr, Ni, As, Pb and Cu contents in leaves of Dichrostachys cinerea, Ficus platyphylla, Isoberlinia doka and Securiniga virosa growing around the Kaduna Refinery and Petrochemical Complex (KRPC) were compared with heavy metal contents of the same species growing in a relatively “clean” environment, during the rainy and dry seasons of 2001. Concentrations of Cr, Ni, As and Pb in the leaves of the plant species monitored were significantly lower during the dry season than during the rainy season, particularly in the polluted site (P < 0.05). The concentrations Sb and Cu were lower only in F. platyphylla and S. virosa. Patterns of accumulation of individual heavy metals were variable. All four species of plants accumulated Pb to a higher degree (P < 0.05), than Cr and Ni, which had accumulation patterns similar, and higher than that of As. Arsenic was the least (P < 0.05) accumulated. Accumulation of Cu was different to other metals, being higher than Pb, Cr, Ni, and As (P < 0.05), and second only to Sb, which was hyper-accumulated in all four plants species. Heavy metal contents of the four species varied between rainy and dry seasons. The differences in metal contents observed between seasons, could be linked to relative availability of cations to plants as influenced by soil moisture content. Variations in pattern of accumulation of individual metals, could be related to the genetically induced capacity of plants to alleviate the toxic effects of heavy metals through mechanisms, which include binding metals to peptides and organic acids, formation of phytochelatins, cellular adaptations, efflux pumping systems and other mechanisms.     

Distribution and Availability of Zinc in Soil Fractions to Wheat on Some Alkaline Calcareous Soils

Experiments under laboratory and greenhouse conditions were conducted to investigate the response of wheat to Zn application in five loess-derived alkaline calcareous soils and to assess the contribution of Zn in various soil fractions on its uptake by plants. Zinc in soil extracted by different reagents was also determined. Total Zn ranged from 58 to 81 mg/kg. On an average 45% of total Zn in all soil fractions was associated with sand, silt and clay. Whereas silt alone held 33% of total Zn among soil fractions in the five soils. Ammonium acetate extractable and acid residual Zn (Sand, silt and clay) explained 98% of variation of Zn in plants, and 70 or 75% of Zn in the AB-DTPA extract and DTPA extract respectively. Application of 10 mg Zn/kg soil significantly (P < 0.01) increased plant shoot dry weight, Zn concentration and total Zn content in plants over control. Concentration of Zn in plants was significantly positively correlated with Zn extracted with DTPA and AB-DTPA in soils.     

中国5种典型土壤的侵蚀泥沙粒径分布特征

通过天然降雨试验,研究我国5种典型土壤的侵蚀泥沙团粒和单粒粒径分布以及泥沙各级团粒的机械组成特征。2013—2014年汛期(6—9月),监测红壤、紫色土、黄绵土、褐土和黑土径流小区的降雨产流事件,收集侵蚀泥沙样品,利用湿筛法和吸管法测定其团粒和单粒粒径分布;同时,筛选出泥沙各级团粒样品,进一步测定其单粒粒径组成。结果表明:(1)侵蚀泥沙粒径分布是土壤质地和降雨强度综合作用的结果,团粒粒径分布更适合作为表征泥沙输移的指标;(2)5种土壤的侵蚀泥沙皆表现出粉团(0.002~0.05mm)和黏团(0.002mm)的明显富集;(3)在泥沙单粒粒径分布方面,除红壤的粉粒(0.002~0.05mm)和黏粒(0.002mm)有轻微富集外,其余4种土壤的各级单粒均无明显富集;(4)红壤侵蚀泥沙粉团(0.002~0.05mm)中的黏粒含量最多,其余4种土壤侵蚀泥沙机械组成和各级团粒的机械组成均与原土接近。     

花岗岩崩岗崩积体颗粒组成及分形特征

崩岗崩积体土质疏松,抗侵蚀能力弱,其颗粒组成及分形维数有其自身的特性。采用激光粒度分布仪对花岗岩崩岗崩积体及崩壁土样的颗粒进行测定,对其土壤颗粒组成及分形特征进行比较分析。结果如下:崩积体土壤以砾石、砂粒、粉粒含量为主,黏粒含量极低,土壤质地主要为砾石土;崩积体各层次土壤颗粒分形维数均值为2.61～2.70,分形维数值较低,反映了其细颗粒损失情况;黏粒含量是影响土壤颗粒分形维数的主要因素;崩壁土体的颗粒分形维数大小能够表征土壤的理化特征,而崩积体土壤颗粒分形维数无法真实反映崩积体的理化性质。     

耕作侵蚀对紫色土坡耕地土壤水分分布的影响

通过短期连续耕作45次,模拟长期耕作对土壤水分分布的影响,利用TDR法按冬小麦5个生长期测定对照区与试验区(实施45次强烈耕作)土壤耕层(0-16.5cm)水分。结果表明,试验区土壤含水量比对照区低8.74%～25.49%,而土壤含水量变异性却比对照区高11.9%～399.8%,表明强烈耕作增大了土壤耕层含水量在坡面的变异性。对照区与试验区土壤含水量分布的差异主要表现在坡顶和肩坡,这种差异可能主要是由耕作侵蚀引起的。耕作侵蚀使上坡土壤发生流失,使土壤贮水性下降,导致试验区上坡土壤耕层含水量显著减小;耕作沉积使下坡土壤发生累积,但对试验区下坡土壤耕层含水量无显著影响。     

Distribution of Boron in Different Fractions in Some Alkaline Calcareous Soils

Distribution of boron (B) in different fractions is still not well defined when it is applied in B-deficient alkaline calcareous soil and after harvesting of the sown crop. In the present greenhouse experiment with green gram crop, three B-deficient soils with calcium carbonate contents of 0.8 (S I), 2.1 (S II), and 4.6 (S III) percent were collected from different sites in Ludhiana and Bhatinda Districts, Punjab, India. The treatments composed of five levels of soil-applied B (0, 0.5, 0.75, 1.0, and 1.5 mg B kg^?1) soil and the experiment was laid out in Completely Randomized Design (CRD) factorial design with three replications. Mean readily soluble, specifically adsorbed, and oxide-bound B fractions got increased significantly with increase in B applications. Distribution of readily soluble B was more in low calcareous soil than in high calcareous soil. Mean values of specifically adsorbed, oxide-bound, residual, and total B were significantly more in high calcareous soils as compared to low calcareous soils. At maturity, specifically adsorbed B converted into other fractions to maintain equilibrium in soil solution. Organically bound B was greater than the oxide-bound B fraction. Among all fractions, residual fraction accounted for the major portion of the total B. Available B was negatively and significantly correlated with calcium carbonate (CaCO₃) content of soil (r = ?0.99*). At the same time, specifically bound B was also negatively and significantly correlated with readily soluble B (r = ?0.99*) whereas organically bound B was positively correlated with organic carbon content of soil (r = ?0.99*).     

坡度对侵蚀产沙及其粒径分布的影响

利用人工模拟降雨试验,分析北京山区普通褐土在不同坡度条件下的产流产沙状况和侵蚀泥沙的粒径分布规律。结果表明,随着坡度的增大,侵蚀模数呈现先增加后减少的趋势,临界坡度为25°,对应的侵蚀模数为19.7t/hm~2。在研究的5个坡度条件下,侵蚀泥沙都以粉粒为主。当坡度从0增大至30°,0.002mm的粘粒含量无明显变化;0.002~0.02mm的细粉粒含量先减少后增加;0.02~0.25mm粗粉粒、极细砂粒和细砂粒含量则呈现先增加后减少的趋势。临界坡度为20°,此时细粉粒含量最少,极细砂粒和细砂粒含量最多。与原土相比,侵蚀泥沙在不同粒级存在富集。主要富集粒径随坡度增加先增大后减小。20°坡度时富集粒径最大,为细砂粒(0.1~0.25mm)。     

激光衍射法测定土壤粒径分布的研究进展

常见的土壤粒径分布测试手段有筛分法、沉降法(包括吸管法和密度计法)、激光衍射法等。近年来,由于激光衍射法分析土壤粒径分布具有操作简单、效率高、测试样品用量小、适合批量样品测定的特点,其在土壤粒径分布的测定中得到越来越广泛的应用。本文介绍了激光衍射法测定土壤粒径分布的基本原理和分析方法,综述了该技术在测定土壤粒径分析方面的国内外研究进展,重点分析了激光衍射法测定土壤粒径分布的影响因素,并对激光衍射法测定土壤粒径分布的应用前景进行了展望。研究表明,激光衍射法通过转换方程可以获得精确的结果。在保证足够大的样本量、土壤样本包含多种质地类型,且完善的前处理条件下,可以建立稳定的、适用于大范围预测的模型。激光衍射法测定土壤粒径分布虽然受到一些因素的影响,例如前处理方法、仪器设置以及样品用量等,但是激光粒度仪为粒度测定提供了高效快速的技术手段,为精准农业和数字农业的发展提供了先进的技术支撑。     

Size Distribution of Dispersed and Aggregated Particles and of Soil Pores in 12 Danish Soils

Abstract

Soil texture, aggregates in different size classes and water retention at several water potentials were measured in the top layers of 12 Danish soils. Size frequency curves of dispersed and aggregated soil particles and of soil pores were calculated using numerical differentiation of sum curves, which were obtained from measured data through interpolation procedures. Soils which originated from water sediments had narrow peaks with approximately lognormal distribution of dispersed soil particles and of soil pores, reflecting the sorting action of the water. Moraine soils appeared to have broad and flat frequency curves of dispersed soil particles, some of which were bimodal or skewed. These soils exhibited a typical bimodal size distribution of soil pores. Degree of aggregation was determined primarily by the soil content of clay, 10% or more creating stable macroaggregates of 2–6 mm diameter. A comparison of the frequency curves for soil pore size to a generalized four-parameter mathematical expression relating matric potential and volumetric water content revealed that the model fitted the empirical data reasonably well for the well-sorted water-sedimented soils, while in the case of the bimodal pore size soils a deviation of differing magnitude was observed. From the investigation it is recommended that in most cases, quantities of particles and pores in soil should be related to size with frequency rather than cumulative expressions.