Cu and Ni Mobility and Bioavailability in Sequentially Conditioned Soils

The potential ecological hazard of metals in soils may be measured directly using a combination of chemical and biological techniques or estimated using appropriate ecological models. Terrestrial ecotoxicity testing has gained scientific credibility and growing regulatory interest; however, toxicity of metals has often been tested in freshly amended soils. Such an approach may lead to derivation of erroneous toxicity values (EC₅₀) and thresholds. In this study, the impact of metal amendments on soil ecotoxicity testing within a context of ion competition was investigated. Four coarse-textured soils were amended with copper (Cu) and nickel (Ni), incubated for 16 weeks and conditioned by a series of total pore water replacements. Rhizon^TM extracted pore water Cu, Ni, pH and dissolved organic carbon (DOC) concentrations were measured after each replacement. Changes in ecotoxicity of soil solutions were also monitored using a lux-based biosensor (Escherichia coli HB101 pUCD607) and linked to variations in soil solution metal and DOC concentrations, pH and selected characteristics of the experimental soils (exchangeable calcium (Ca) and magnesium (Mg)). Prior to conditioning of soils, strong proton competition produced relatively high EC₅₀ values (low toxicity) for both, Cu and Ni. The successive replacement of pore waters lead to a decline of labile pools of metals, DOC and alleviated the ecotoxicological protective effect of amendment impacted soil solution chemistry. Consequently, derived ecotoxicity values and toxicity thresholds were more reflective of genuine environmental conditions and the relationships observed more consistent with trends reported in historically contaminated soils.     

Mineralogy and Arsenic Mobility in Arsenic-rich Brazilian Soils and Sediments (11 pp)

Background   Soils and sediments in certain mining regions of Brazil contain an unusually large amount of arsenic (As), which raises concerns that mining could promote increased As mobility, and thereby increase the risks of contaminating water supplies. Objectives   The purpose of this study was to identify the most important factors governing As mobility in sediments and soils near three gold-mining sites in the State of Minas Gerais, Brazil. Methods   Surface and sub-surface soil samples were collected at those sites and characterized by chemical and mineralogical analyses. Oxalate (Feo) and citrate-bicarbonate-dithionite (Fed) iron contents were determined by atomic absorption spectroscopy (AAS). Arsenic mobilization was measured after incubating the samples in a 2.5 mM CaCl2 solution under anaerobic conditions for 1, 28, 56, 84, or 112 days. The solution concentrations of As, Fe, and Mn were then measured by inductively coupled plasma-mass spectrometry (ICP-MS) and AAS, respectively. Results and Discussion   Results indicated that As mobilization is largely independent of both the total As and the Feo/Fed ratio of the solid phase. Soluble As is roughly controlled by the Fe (hydr)oxide content of the soil, but a closer examination of the data revealed the importance of other highly weathered clay minerals and organic matter. Large amounts of organic matter and a low iron oxide content should favor As leaching from soils and sediments. Under reducing conditions, As is mobilized by the reductive dissolution of Fe and/or Mn oxides. However, released As may be readsorbed depending on the sorptive properties of the soil. Gibbsite is particularly effective in adsorbing or readsorbing As, as is the remaining unreduced fraction of the iron (hydr)oxides. Conclusion and Outlook   In general, low soluble As is related to the presence of gibbsite, a large amount of iron oxides, and a lack of organic matter in the solid phase. This has environmental significance because gibbsite is thermodynamically more stable than Fe oxides under anaerobic conditions, such as those found in waterlogged soils and lake sediments.     

Evaluation of Pb and Ni Mobility to Groundwater in Calcareous Urban Soils of Ancona, Italy

This study was performed on 21 soils with the aim of establishing whether Pb and Ni adsorption/desorption parameters could be considered as good indicators of the risk of groundwater pollution. Results showed that high pH values in soil caused a totally irreversible Pb adsorption, thus excluding any risk of Pb groundwater pollution. Sorption/desorption studies, quantified by the desorption index (DI), showed that Ni retention was only partly affected by the basic pH values but it was also due to the electrostatic attraction processes occurring on soil surfaces, as demonstrated by the partial reversibility of the Ni sorbed. This justifies possible risks of Ni groundwater pollution. The results of a monitoring research confirmed these findings. Results suggested that the adsorption/desorption parameters, namely DI, are promising indicators to predict the risk of groundwater pollution from metals in calcareous soils.     

Mobility of Organic and Inorganic Zinc Fertilizers in Soils

Abstract

Zinc sulfate (ZnSO₄ · H₂O) has traditionally been the “reliable” source of zinc (Zn) fertilizer, but other sources of Zn are also available. Some are derived from industrial by‐products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn mobility in Zn sources derived from these various by‐products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this column study was to compare the mobility of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. The sources included three granular inorganic Zn sources, two granular organically complexed Zn sources, and liquid ZnEDTA. Soil columns were leached five times with deionized water. Leaching events were separated by approximately 48 h. At the conclusion of the leaching phase, columns were analyzed for plant‐available Zn. Water solubility was the primary factor affecting Zn movement, not total Zn content or organic complexation of the fertilizers. The Zn sources evaluated can be separated into three groups: ZnEDTA, ZnLigno, and ZnSO₄ were the most mobile Zn sources; the ZnOx55 was less mobile, but seemed mobile enough to meet crop needs; ZnOx26 and ZnSuc were relatively immobile Zn sources.     

虱螨脲在土壤中的降解、吸附和移动特性

采用室内模拟试验方法,研究了虱螨脲在3种土壤中的降解、吸附和移动特性。结果表明：25℃下,虱螨脲在江西红壤中的降解半衰期为101d,属于中等降解农药;在太湖水稻土和东北黑土中的降解半衰期分别为74.5d和55.5d,属于较易降解农药。土壤有机质含量是影响虱螨脲降解速率的主要因素;3种土壤对虱螨脲具有较强的吸附性,且土壤有机质含量越高,对虱螨脲的吸附性越强;3种土壤对虱螨脲的吸附自由能变化均小于40kJ·mol^-1,属于物理吸附;虱螨脲在土壤中不易移动,正常条件下不会造成地下水的污染。     

Liming Decreases the Vertical Mobility of Potassium in Acidic Soils

Liming increases soil negative charges and thus affects the chemical equilibrium of cations between the solid phase and the soil solution with consequences for the mobility of cations. The effects of lime and potassium chloride (KCl) addition on the vertical movement of potassium (K), calcium (Ca), and magnesium (Mg) were investigated in two Brazilian soils. The experiment was carried out in leaching columns. Treatments included a combination of rates of KCl (0, 50, 100, and 200 mg kg^?1 K) and acidity levels (without and with liming). Seven water percolations (400 mL per column) were performed at weekly intervals, totaling an equivalent to 357 mm of rain. Raising the soil pH decreased the leaching of K, in both soils, up to 50% because of the increase of its electrostatic adsorption on created negative charges. Addition of KCl increased the percolation of K, Ca, and Mg proportionally to the rate applied, and it was more efficient than calcium carbonate to percolate Ca in both soils. Liming must be taken into consideration when K leaching or plant needs of K are estimated in predominantly variable-charge soils.     

Multivariate Statistical and GIS-Based Approach for the Identification of Mn and Ni Concentrations and Spatial Variability in Soils of a Humid Mediterranean Environment: La Rioja, Spain

Limnologists have regarded temporal coherence (synchrony) as a powerful tool for identifying the relative importance of local-scale regulators and regional climatic drivers on lake ecosystems. Limnological studies on Asian reservoirs have emphasized that climate and hydrology under the influences of monsoon are dominant factors regulating seasonal patterns of lake trophic status; yet, little is known of synchrony or asynchrony of trophic status in the single reservoir ecosystem. Based on monthly monitoring data of chlorophyll a, transparency, nutrients, and nonvolatile suspended solids (NVSS) during 1-year period, the present study evaluated temporal coherence to test whether local-scale regulators disturb the seasonal dynamics of trophic state indices (TSI) in a giant dendritic reservoir, China (Three Gorges Reservoir, TGR). Reservoir-wide coherences for TSI_CHL, TSI_SD, and TSI_TP showed dramatic variations over spatial scale, indicating temporal asynchrony of trophic status. Following the concept of TSI differences, algal productivity in the mainstream of TGR and Xiangxi Bay except the upstream of the bay were always limited by nonalgal turbidity (TSI_CHL?TSI_SD <0) rather than nitrogen and phosphorus (TSI_CHL?TSI_TN <0 and TSI_CHL?TSI_TP <0). The coherence analysis for TSI differences showed that local processes of Xiangxi Bay were the main responsible for local asynchrony of nonalgal turbidity limitation levels. Regression analysis further proved that local temporal asynchrony for TSI_SD and nonalgal turbidity limitation levels were regulated by local dynamics of NVSS, rather than geographical distance. The implications of the present study are to emphasize that the results of trophic status obtained from a single environment (reservoir mainstream) cannot be extrapolated to other environments (tributary bay) in a way that would allow its use as a sentinel site.     

Assessment of the Regional Variation in Weathering Rates of Loess and Clay Soils in The Netherlands

To calculate critical acid loads or to predict elementconcentrations in the soil solution, information on weatheringrates is essential. Several studies have taken place in theNetherlands to obtain weathering rates for non-calcareous sandysoils. Recently information on weathering rates in less vulnerable loess and clay soils have become available. However,up to now no system is available to estimate weathering rates ona regional scale by relating them to regionally available soilproperties.To obtain weathering rates of loess and clay soils on a regionalscale for the Netherlands, the applicability of a statisticalregression model and the process based PROFILE model have beenevaluated. Both models were calibrated on a set of laboratoryexperiments. To evaluate their predictive power, both methodswere validated on a number of sites for which field weatheringrates were available.Predictions with the statistical model, for the individual basecations, were generally within a factor 2 of the calculatedhistorical weathering rates, except for Ca, which wasoverestimated, by a factor 3 to 4. PROFILE stronglyoverestimated all weathering rates using both standard parameters and in particular after calibration on the laboratoryrates. However, PROFILE predicted weathering rates of the loesssoils quite good after calibration on historical weatheringrates, indicating that the downscaling procedure used in PROFILEto translate laboratory to field weathering rates is inadequatefor the considered soils.The statistical model was applied to predict weathering rates,for the Netherlands on a 1 × 1 km grid scale. Weathering rates at the present pH values in forested loess and clay soilsranged from 135 to 6000 mol_c ha^-1 a^-1 in loesssoils and from 100 to 1750 mol_c ha^-1 a^-1 in claysoils.     

Chemical Extractability of Lead in Field-Contaminated Soils: Implications for Estimating Total Lead

Lead (Pb) is frequently present in urban soils at concentrations of concern for human health. Regulations for Pb are based on total soil concentrations as determined by acid digestion, but a less expensive screening test for Pb would be useful in facilitating more thorough soil testing of urban areas if it could be shown to correlate strongly to total soil Pb. In this study, three extractants (0.1 M citrate, MM, and 1 M nitric acid) were evaluated for their ability to estimate the total Pb in contaminated soils. Nitric acid not only extracted a greater fraction of total soil Pb but also produced the strongest correlation to total Pb and is concluded to be the superior extractant for a soil Pb screening test. As the spatial distribution of Pb was observed in selected soils to be highly heterogeneous on the micron scale, thorough soil homogenization prior to testing is recommended.     

Retention Capacity and Environmental Mobility of Pb in Soils along Highway Corridor

Although lead (Pb) emissions have dropped drastically with the phase-out of tetra-ethyl lead (TEL) as a fuel additive, Pb deposited along highway corridors continues to be of concern because of its toxicity. This paper provides comprehensive data on the extent and distribution of Pb in roadside soils, Pb interaction with soils as a function of soil composition, the retention capacity of soil based on batch adsorption tests, the retention mechanism of Pb using selective sequential extraction, the potential for mobility using batch desorption tests with simulated rain and winter road salt, and column leach tests. Highway soils on high-traffic sections near Burnaby, Canada were found to have Pb accumulations up to 1628mg/kg soil. Contamination was mainly in the top 0.3m, with concentrations rapidly decreasing to the background level at a depth of 0.6m. The top layer contained more organic material and had a high adsorption capacity. Highway soils were found to have 3–10 times higher Pb adsorption capacities than the amount currently deposited. Selective sequential extraction indicated low exchangeable Pb in highway soils. Batch desorption tests with leaching solutions of H₂O (pH 5.5), HNO₃ solution (pH 4.0) and aqueous NaCl solution (0.17M) indicate low likelihood of significant leaching. Selective sequential extraction, leachate extraction and desorption tests show that Pb has limited mobility in highway soil.     

Mineralogy and Fertility Status of Selected Soils of the Eastern Cape Province,South Africa

Abstract

Thorough knowledge of cultivated soils is necessary for their informed and sustainable management. This study was carried out to gain a better understanding of cropped soils in the Eastern Cape Province of South Africa. The mineralogical and chemical composition and nutrient status of topsoils collected from homestead gardens and fields of smallholdings in 5 of the 36 magisterial districts where smallholder farming prevails in the Province were determined. These data were supplemented with results of soil analyses conducted by an Analytical Services Laboratory that obtains its samples from the 31 magisterial districts where large‐scale farms are dominant. The soils studied were similar mineralogically, and all had a clay fraction that was dominated by quartz, mica, and/or kaolinite, which is fairly typical for many tropical and subtropical soils. Elemental analysis showed that the soils were generally low to very low in their total content of nutrients, except for sulfur (S), manganese (Mn), zinc (Zn), copper (Cu), and boron (B), reflecting the marine and sedimentary nature of their parent materials. The available nutrient status of the cultivated soils was generally low to very low, especially those found in smallholder fields. This was attributed to low soil organic matter levels and low geological reserves of some nutrients notably phosphorus (P), potassium (K), and calcium (Ca), coupled with continuous cultivation of the lands without adequate nutrient replenishment. Depending on location, 75–100% of the fields tested low in pH, 62–100% were low in organic carbon, 83–100% were low in extractable K, 62–93% were low in extractable Ca, and 79–100% were deficient in available phosphorus. The nutrient status of soils receiving moderate to high amounts of nutrients was generally satisfactory, as revealed by the nutrient content of garden soils found on smallholdings and the fields on large‐scale farms. In all cases, soil pH was low to critically low. The findings are used to propose a soil fertility management strategy for the communal areas of the Province.     

Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在红壤胶体和非胶体颗粒上吸附的比较

研究了湖南长沙和海南昆仑的2种红壤胶体和非胶体的矿物组成、阳离子交换量(CEC)及Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在土壤胶体和非胶体颗粒表面的吸附行为,以明确红壤胶体对土壤表面化学性质的贡献。X射线衍射分析结果表明,两种红壤胶体的矿物组成均以次生矿物为主,次生矿物又以1∶1型高岭石所占比例最高。土壤非胶体颗粒中石英等原生矿物含量较高。土壤铁铝氧化物主要富集在土壤胶体部分,土壤胶体颗粒中游离氧化铁和游离氧化铝含量明显高于非胶体颗粒,如湖南长沙红壤胶体颗粒游离氧化铁的含量为78.03 g kg~(-1),而非胶体颗粒中仅为9.93 g kg~(-1)。土壤胶体颗粒的CEC显著高于非胶体颗粒部分,2种红壤胶体的CEC约为非胶体的12倍。等温吸附实验结果表明,土壤胶体颗粒对Cu(Ⅱ)、Pb(Ⅱ)与Cd(Ⅱ)的最大吸附量和吸附亲和力均显著大于非胶体颗粒,湖南红壤胶体对3种重金属的吸附量大于海南红壤胶体,与土壤胶体的矿物组成和CEC大小一致。Cd(Ⅱ)在红壤胶体和非胶体颗粒表面主要发生静电吸附,而静电吸附和非静电吸附两种机制均对Cu(Ⅱ)和Pb(Ⅱ)的吸附有重要贡献。     

Toxicity of Cu and Cd in Soils and Detoxication by Additives

Results from laboratory experiments indicated that the concentrations and toxicities of both water-soluble and 0.1 M HCl-extractable Cu and Cd from soils were in the order of red soil> yellow brown earth> black earth. The toxicity of soil varied with the concentrations of metals. The form, concentration and toxicity of Cu and Cd in soils were determined by cation exchange capacity, content of organic matter and composition of clay minerals in the soil. Addition of CaCO3 could significantly decrease the concentration and toxicity of water-soluble and 0.1 M HCl-extractable Cu or Cd from the red soil, and could notably transform the Cu and Cd from the water-soluble or exchangeable form into the organic, free oxides-occluded or sulfic form.     

表层沉积物(生物膜)及其各组分对自然水体中Cu,Zn的富集

利用选择性萃取技术对表层沉积物(生物膜)中的锰氧化物、铁/锰氧化物及有机质进行选择性萃取分离,同时考察同步萃取下来的Cu,Zn的分离情况,并运用加和模型研究表层沉积物(生物膜)中各组分对自然水体中重金属Cu,Zn的富集能力。结果表明,生物膜对自然水体中重金属Cu,Zn的富集能力大于表层沉积物,表层沉积物(生物膜)中的金属(铁、锰)氧化物对重金属Cu,Zn的单位富集能力远远大于有机质(1~2个数量级),有机质对重金属的单位富集能力可忽略不计,金属(铁、锰)氧化物是表层沉积物(生物膜)富集自然水体中重金属的主要控制因素。     

Concentration Changes of Cd, Ni and Zn in Sugarcane Cultivated Soils

In the southwest of Iran over 130,000 ha of land are under sugarcane (Saccarum officinarum). In these sugarcane fields, about 400 kg ha^?1 diamonium phosphate (DAP) and 400 kg ha^?1 urea are applied annually. Four sugarcane growing sites were selected for this study: Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 years, respectively. For each area, soil samples (0–30 cm) were taken from a transect of uncultivated, and both furrows and ridges of cultivated land. Electrical conductivity (EC), pH, clay, and calcium carbonate and organic carbon (OC) contents, Cl, Cd, Ni and Zn of 101 soil samples were measured. Cadmium profile distribution to a soil depth of 300 cm was determined, and the heavy metal concentrations in sugarcane and the associated soil samples of the three sugarcane sites were measured. The Cd and Ni contents among the sugarcane sites differed where Cd was related to clay content and Ni was related to OC content of soils. Cadmium content in sugarcane cultivated soil was lower compared to uncultivated soil even after years of application of P fertilizers. Nickel and Cd contents of sugarcane were much higher than levels in top soils but there was no significant relationship between Cd or Ni contents of sugarcane and soil chemical properties. The Zn content of soils decreased as either EC or Cl concentration of soils increased. There were no significant differences in Zn contents between different sugarcane sites and also between cultivated and uncultivated soils. Results also indicated that Cd was accumulated in bagasse and Ni was primarily accumulated in bagasse and molasses, but these heavy metals of white sugar were lower than the detectable values.     

Contaminant Mobility in Soils Amended with Fly Ash and Flue-Gas Gypsum: Intact Soil Cores and Repacked Columns

The impact of the land application of coal combustion by-products, fly ash (FA) and flue-gas desulfurization gypsum(FDG), to coarse-textured soils of the southeastern U.S.A. wasinvestigated using batch and dynamic column techniques. Two FAsamples, one an alkaline FA (Alk-FA) and the other an acidic FA(Acid-FA), were evaluated alone and in combination with FDG assoil amendments to an Appling loamy sand (Typic Hapludults). Theeffects of these waste products on clay dispersion, soilhydraulic conductivity (K_sat) and the migration ofcontaminants such as Arsenic (As) and Boron (B) were studiedusing intact soil cores and repacked soil columns. FA or combinationsof FA + FDG were applied to the surface of intact soil cores (10 Mg ha^-1) and repacked soil columns or incorporated withinrepacked soil columns. The columns were saturated and thenleached for a prescribed number of pore volumes to simulateleaching conditions in the field. Effluent pH, electricalconductivity (EC), and turbidity were monitored and leachatefractions were collected for B, As, Ca, Mg, K and Na analysis.Both FA materials were ineffective at decreasing the inherentdispersibility of clay from the A_p horizon in batch tests.In fact, high application rates of the Alk-FA induced some claydispersion in the well-flocculated B_t soil materials, andcolumn results suggest that incorporating the Alk-FA within thesurface soil may actually reduce K_sat. In contrast,treatments with FDG were highly effective at inducing rapid clayflocculation in batch tests and eliminating effluent turbidityfor intact and repacked soil columns. Boron was readily mobilefrom both intact and repacked soil columns, a majority of whichleached from the columns within the first three pore volumes.Boron leaching was greater for combined treatments (FA + FDG),possibly indicative of enhanced solubilization in the presenceof FDG or sulfate (SO₄ ^2-) competition for sorptionsites. Arsenic levels present in the leachates from FA and FDGcolumns were generally lower than control columns and roughlycorrelated with effluent turbidity. Combined treatments (FA +FDG) enhanced Mg and K leaching due to the added competition ofCa for cation exchange sites. Following leaching, the intactsoil cores were sectioned at 5 cm intervals and the pH and EC ofthe soil, as well as the vertical distribution of As and B, weredetermined. Levels of residual As were only slightly higher in the upper section of the FA-amended columns, showing little downward movement, but no clear trend in residual B was observed due to its greater mobility.     

Plasticity,Mineralogy, and WRB Classification of Some Typical Clay Soils along the Two Major Rivers in Croatia

Eurasian Soil Science - Quantification of soil plasticity is usually based on Atterberg limits or indices, which are then used for engineering and agricultural purposes on clay soils. Because these...     

Simultaneous Sorption of Cd,Cu, Ni,Zn, Pb,and Cr on Soils Treated with Sewage Sludge Supernatant

Disposal of sewage sludge creates the potential for heavy metal accumulation in theenvironment. This study assessed nine soils currently used as Dedicated Land Disposal units(DLDs) for treatment and disposal of municipal sewage sludge in the vicinity of Sacramento,California. Adsorption characteristics of these soils for Cd, Cu, Ni, Zn, Pb, and Cr were studiedby simultaneously mixing these elements in the range of 0-50 µmol L-1 with sludgesupernatant and reacting with the soil using a soil:supernatant ratio of 1:30, pH = 4.5 or 6.5, andconstant ionic strength (0.01 M Na-acetate). The concentration of metals in the supernatant wasdetermined after a 24 hr equilibration period. Adsorption isotherms showed that metal sorptionwas linearly related to its concentration in the supernatant solution. The distribution coefficientKd (Kd = concentration on solid phase/concentration in solution phase) was computed as theslope of the sorption isotherm. The distribution coefficients were significantly correlated to soilorganic matter content for Ni, Cu, Cd, and Pb at pH 4.5 and for Ni, Cu, Zn, and Cd at pH 6.5.There was also a correlation between Kd and soil specific surface area but no relationship to othersoil properties such as CEC, clay content, and noncrystalline Fe and Al materials. Therefore, soilorganic carbon and surface area appear to be the most important soil properties influencing metaladsorption through formation of organo-metal complexes. The Kd values for all elements werehigher at pH 6.5 than at 4.5. Selectivity between metals resulted in the following metal affinitiesbased on their Kd values: Pb>Cu>Zn>Ni>Cd≈Cr at pH 4.5 andPb>Cu≈Zn>Cd>Ni>Cr at pH 6.5.     

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.