Hilda Hernádi

Comparison of Nonaqueous Phase Liquids' Conductivity and Air Permeability of Different Soils

It was recently shown that estimated transport parameters for nonaqueous phase liquids (NAPLs) could differ significantly from measured parameters because of poor estimates for fluid conductivity. Most of the estimation procedures of the different multiphase flow simulators assume that porous media are rigid and noninteracting (ideal porous medium). This assumption is not valid in aggregated soil systems consisting in part of clay minerals. Inadequate conductivity estimates may be a direct result of desaggregation or clay volume changes (pore‐size distribution changes) when contact with different fluids occurs. To expand the experimental data set of models describing the movement of organic liquids polluting the soils and possibly to discover new relationships between the NAPL conductivity and the other soil parameters, a series of experiments was set up in which the air permeability was measured with a PL 300 permeameter (UGT) and the fluid (NAPL and water) conductivity was measured using the falling head method. The measurements were carried out on artificial soil columns. The soils originated from different horizons of characteristic Hungarian soils. The relationships between the NAPL conductivity and the various other soil parameters were examined statistically. To give a better prediction for the NAPL conductivity, a new estimation method that is based on the easily measurable soil parameters was suggested.

Particle-size and organic matter effects on structure and water retention of soils

Abstract Water storage and flow in soils are highly dependent on soil structure, which strongly determines soil porosity. However pore size distribution can be derived from soil water retention curve (SWRC). Structural characteristics of cultivated arable fields (693 soil profiles, 1773 samples) and soils covered by treated forest stands (137 soil profiles, 405 samples) were selected from the MARTHA Hungarian soil physical database, and evaluated for expressing organic matter effects on soil structure and water retention. For this purpose the normalized pore size distribution curves were determined for the selected soils, plus the modal suction (MS) corresponding to the most frequent pore size class of the soil. Skewness of soils’ pore size distribution curves are found different. The quasi-normal distribution of sandy soils are transformed into distorted in clayey soils. A general growing trend of MS with the ever finer soil texture was shown. Sandy soils have the lowest average MS values, i.e. the highest most frequent equivalent pore diameter. Silty clay and clay soil textures are characterized by the highest MS values. A slight effect of land use and organic matter content is also observable in different MS values of soils under forest vegetation (’forest’) and cultivated arable land (‘plough fields’). MS values of the two land uses were compared statistically. The results of the analyses show that certain soil group’s MS are significantly different under forest vegetation and cultivation. However this difference can be explained only partly and indirectly by the organic matter of different plant coverage in the land use types.

Nonaqueous-Phase Liquid Retention of Mineral Mixture Series Containing Different Clay Minerals

The pollution of soils with nonaqueous-phase liquids (NAPL) may endanger the quality of soils, their utilization, and the groundwater reservoir. To develop NAPL transport models, the most important soil parameters are the hydrophysical properties of the solid phase such as the retention capacity. Because the measurement of these soil properties is time-consuming and costly, in most cases they are estimated. However, the commonly used estimation methods are mostly validated with laboratory measurements using soil columns made from sand, quartz, or glass-bead samples, with negligible contents of clay and organic matter. These estimation methods consider the soil as ideal porous media and thus may not provide appropriate results for soils with variably physical and chemical properties. In the 1990s a research program commenced at this university to create an appropriate estimation method for predicting the NAPL retention capacity of soils. Two estimation methods, the Leverett equation and the prediction with pedotransfer functions (PTF), were compared. We assumed that the oil retention of soil is sufficiently predictable from basic soil properties, but we later discovered that these models needed to be refined further because NAPL retention in soils may be influenced by different properties at a higher pressure level than at lower pressure. Moreover, the quantity and the quality of clay minerals in soils may also influence the retention capacity of soils. The aim of this study was to determine the effect of different investigated soil parameters on NAPL retention measured at different pressure values. A series of mineral mixtures containing different clay minerals were used, the PTFs were established, and the role of the main soil properties in NAPL retention was investigated with statistical analysis.

Climate sensitivity of soil water regime of different Hungarian Chernozem soil subtypes

In this study the possible effects of two predicted climate change scenarios on soil water regime of Hungarian Calcic Chernozem soils has been investigated. Soil profiles classified as Calcic Chernozem — in total 49 — were selected from the MARTHA soil physical database that incorporates soil data at national scale. These profiles were subdivided into three groups (sandy loam, loam and clayey loam) in accordance with their mechanical composition. Soil water retention curves were scaled separately for each of the three textural groups, using similar media scaling in order to represent the variability of soil hydrophysical data with one parameter, the scaling factor (SF). Reference soil profiles were chosen according to the cumulative distribution function of the scaling factor, six for each textural group. Daily downscaled meteorological data from A2 and B2 climate scenarios of the Hadley Centre (2070–2100) and data from a reference period (RF, 1961–1990) were used in this study to characterize different climatic situations. Nine representative years were selected in case of all the three scenarios, using the cumulative probability function of the annual precipitation sum. Scenario analyses were performed, validating the SWAP soil water balance simulation model for the 18 reference soil profiles and 27 representative years in order to evaluate the expected changes in soil water regime under different from the present (RF) climatic conditions (A2 and B2 scenarios). Our results show that the scaling factor could be used as a climate sensitivity indicator of soil water regime. The large climate sensitivity of the majority of Chernozem soil subtypes water regime has been proven.

Dataset for Creating Pedotransfer Functions to Estimate Organic Liquid Retention of Soils

Abstract Soil properties characterising pressure-saturation relationships (P-S), such as the fluid retention values or the fitting parameter of retention curves are basic input parameters for simulating the behaviour and transport of nonaqueous phase liquids (NAPLs) in subsurface. Recent investigations have shown the limited applicability of the commonly used estimation methods for predicting NAPL retention values in environmental practice. Alternatively, building pedotransfer functions (PTFs) based on the easily measurable properties of soils might give more accurate and reliable results for estimating hydraulic propertie s of soils and enable the utilisation of the wide range of data incorporated in Hungarian and international datasets. In spite of the availability of several well-established PTFs to predict the water retention of soils only a limited amount of research has been done concerning the NAPL retention of soils. Thus, in our study, data from our recent NAPL and water retention mea surements were collected into a dataset containing the basic soil properties as well. Relationships between basic soil propert ies and fluid retention of soils with water or an organic liquid (Dunasol 180/220) were investigated with principal component analysis. NAPL retention of soil samples were determined with PTFs, based on basic soil properties and their d erived values, and using a scaling method. Result of the statistical analysis (SPSS 13.1) revealed that using PTFs could be a promising alte rnative and could give more accurate results compared to the scaling method both for determining the NAPL saturation or the volumetric NAPL retention values of soils.

Preliminary investigation to estimate soil NAPL retention using parametric pedotransfer functions

Abstract Organic liquid retention of soils is a primary input variable for modelling the nonaqueous phase liquid transport and behaviour in the subsurface. In environmental and soil physical practice, it is mainly determined by scaling based on the water retention of soils or with charts of average empirical values of organic liquid retention or the fitting parameters of hydraulic functions. Predicting the fitting parameters of organic liquid retention curves with pedotransfer functions might be a promising alternative method, but this topic has only been researched to a limited extent. Thus we investigated the applicability of different hydraulic functions (3- and 4- parameter form of the van Genuchten equation and Brutsaert equation) for fitting organic liquid retention characteristics. Multivariate linear regression was used to build and develop pedotransfer functions, modelling relations between original and transformed values of basic soil properties and organic liquid retention. We attempted to generate parametric pedotransfer functions. According to our results, the applicability of hydraulic functions for fitting nonaqueous phase liquid retention curves to the experimental data was proven. The investigations gave promising results for the possibility to estimate soil nonaqueous phase liquid retention with parametric pedotransfer functions.

A talajok mechanikai összetétel vizsgálata pipettás ülepítéses módszerrel: a hazai és a nemzetközi szabvány szerinti eljárások összehasonlítása és konverziója

The particle size distribution (PSD) values obtained for a soil database representing the main Hungarian soil types using the Hungarian standard (MSZ-08-0205-78) and the international standard (ISO/DIS 11277:1994) were compared with the pipette method. The relationship between these PSDs and other physical soil characteristics (upper limit of plasticity according to Arany, water vapour adsorption according to Sik) was also analysed, and a suggestion was made of how these results could be converted into each other. Experience showed that the pre-treatments applied as part of the ISO/DIS method may change the ratio of particle size fractions: there was a significant increase in the clay content, while the silt content decreased to a lesser and the sand content to a greater extent, possibly because some of the particles remain in microaggregate form when the MSZ method is used. The results confirmed the greater accuracy of the ISO/DIS method: the clay contents measured with the ISO/DIS method exhibited stron...

Folyadék-visszatartás, folyadékvezetés és porozitás összefüggései vízzel és/vagy szerves folyadékkal telített talajokban I. Folyadék-visszatartó képesség — Szemle

Modelling the flow and transport of fluids (water and non-aqueous phase liquids or NAPLs) in porous systems or soils requires the accurate and reliable determination of basic input modelling parameters, such as liquid retention (Pc–S) and conductivity (Ksat, Kh). Methods for the determination (measurement and estimation) of water retention and conductivity have improved enormously over the last 60 years (Table 1). Promising results verified the applicability of pedotransfer functions (PTF) and their incorporated versions into software and submodels. However, the development of models was only aimed at improving methods with which these hydrological parameters could be determined for water, while calculations for NAPLs can still only be made indirectly. Several studies (e.g. in the petroleum industry, and research for environmental or hydrological purposes) revealed differences in the relationship between the hydraulic properties and pore system of the porous solid phase. Interactions (swelling-shrinking, ...

Talajminták lézeres szemcseanalízisének módszertani tapasztalatai

A lezerdiffrakcios szemcseanalizis egy korszerű modszer a talajmechanikai vizsgalatokban, am egy egyseges meresi szabvany bevezetese (akar műszerhez kothetően) nagymertekben novelne a meresek reprodukalhatosagat. A meresek tekinteteben kiemelt szerepe van az előkeszitő modszereknek (talajszerkezetet kialakito kotőanyagok roncsolasa, elemi szemcsek diszpergalasa), azonban ezen a teren is hianyzik az egyseges szabvanyositas. A tanulmanyozott kozlemenyek alapjan megallapithato, hogy mind az optimalis mintaelőkeszitesi modszer, mind pedig a legmegfelelőbb műszerbeallitas nagymertekben fugg a merni kivant minta fizikai es kemiai sajatsagaitol. A meresi eredmenyek hagyomanyos ulepiteses modszerrel kapott eredmenyekkel tortenő osszehasonlitasara szolgalo konverzios modszerek (frakcio merethatarvaltasok, illetve konverzios egyenletek) hasznalhatosaga is talajminta- es LDM vizsgalati modszer-fuggő. A lezeres szemcseanalizis alkalmazasa a talajok aggregatum-stabilitas vizsgalata soran igeretes modszertani lehetőseg...