Loam Samples Research Articles

Dielectric Studies of Soil at Various Microwave Frequencies

Abstract: Dielectric constant (real and imaginary parts) of moist soils is calculated at microwave frequency with an empirical model. The model equation is generated by curve fitting experimental data with second order polynomial expression. Two types of sandy loam samples are used to estimation of dielectric constant at frequencies range from 4.0 GHz to 18.0 GHZ. Both soil samples (sandy loam) are differentiated according to their textural composition. The real part of dielectric constant is negatively corelated with microwave frequency while imaginary parts of soil increase as frequency increases.

Investigation of impact of soil texture, depth and gamma ray energy on the mass attenuation coefficient and determination of soil bulk density using Gamma-Ray Spectrometry

The determination of the gamma-ray attenuation coefficient is a critical parameter in the characterization of the extent and diffusion of gamma radiation within intricate materials, such as soil. Soils exhibit a complex and diverse composition, characterized by the presence of several phases, including minerals, gasses, organic matter, water, and metals. The study demonstrates the utilization of gamma-ray spectrometry to determine the mass attenuation coefficient and soil bulk density. The impact of incident gamma-ray energy, soil texture, and soil depth on the mass attenuation coefficient is also investigated. The experimental measurements were conducted utilizing a gamma spectrometer equipped with a 2″ × 2″ NaI(Tl) detector at gamma energies of 0.356, 0.662, and 1.332 MeV using 133Ba, 137Cs, and 60Co sources, respectively. The soil samples corresponding to two textures and three depths were collected from the research farms of the Department of Soil Science, Punjab Agricultural University, Ludhiana. The study revealed that the attenuation coefficient depends on the energy of incident radiation and the nature as well as the composition of the soil. The mass attenuation coefficient was observed to decrease rapidly with the increase in gamma radiation energy. Mass attenuation coefficient was found to be higher for sandy loam compared to sandy clay loam textured soil. Moreover, the attenuation coefficient was higher for the lower depths than the upper depth. The comparison between the experimental and predicted values of the mass attenuation coefficient, utilizing the XCOM-NIST framework, demonstrated a satisfactory level of concordance within a 10% margin for gamma energies measuring 0.356 and 0.662 MeV. However, the agreement was slightly less favorable, with discrepancies of less than 12% for sandy clay loam samples and less than 15% for sandy loam textured soil samples, when examining a higher gamma energy of 1.332 MeV. The measured value of mass attenuation coefficient was used to calculate soil bulk density, which agreed reasonably well with the values obtained with the conventional method. Specifically, the sandy clay loam samples displayed a range of 7–14% deviation, while the sandy loam textured soil samples exhibited a range of 14–23% deviation. The investigation can be expanded to ascertain significant soil properties, such as porosity and moisture content.

Principles for positioning a capillary barrier made of injected mortar in the earth bed

The paper formulates a condition for transferring an “open” freezing system into a “closed” one and proposes calculation criteria for creating a capillary barrier. The solution to the problem of capillary barrier location in the ground is obtained, which is based on linking the zone of intense moisture transfer to temperature isolines in the freezing massif. Several existing solutions for determining the temperature field diagram in the road structure at the time of maximum freezing have been considered. A general algorithm for solving the problem of capillary barrier location in the earth bed has been compiled. To verify the obtained solutions, a series of laboratory tests were carried out to determine the magnitude of moisture accumulation and frost heave of sandy loam and loam samples with plasticity number from 0.05 to 0.13 with different location of capillary barrier relative to frost zone.

Adsorption-desorption and degradation of colistin in soils under aerobic conditions

Colistin has broad-spectrum activity against Gram-negative bacteria and has been considered as the last-resort treatment for multiantibiotic-resistant Gram-negative bacteria infections in human. And it is also world widely utilized as a veterinary medicine for the promotion of growth, prevention and control of diseases in livestock and poultry. Extensive use of colistin in husbandry results in the introduction of large amounts of colistin to the surrounding environment via animals’ urine and feces, potentially inducing the prevalence of colistin resistance bacteria and the impact of the ecological environment. The study investigated the adsorption, desorption and degradation of colistin in soils using high sensitivity UPLC-MS/MS assays. An MS based assay was established to directly determine colistin in the soil. It was observed that the moderate adsorption affinity of colistin to the three soils with adsorption strength (1/n) ranging from 0.6897 to 1.3333. Colistin exhibited the highest adsorption affinity to the sandy loam, followed by the sand and loam. Despite of different characteristics of three soils, the adsorption capacity of the three soils was comparable. The adsorption of colistin to the three types of soils analyzed was irreversible. The degradation experiments showed that the degradation of colistin in the sandy loam was relatively slow with a degradation half-life in a range of 13.2–29.7 days when colistin was applied to the sandy loam at a level of 10 ~ 40 µg/g. The degradation of colistin occurred in the mixture of the sandy loam and feces recovered from the colistin treated broiler as well. 25% of colistin remained in the mixture under environmental conditions after 14 days. Composting the sandy loam by directly covering the soil surface with colistin treated broilers’ feces resulted in the introduction of colistin to the sandy loam. Colistin was observed in both the topsoil from the contact surface and sandy loam samples collected 20 cm below the contact surface. The understanding of adsorption-desorption behaviors, degradation and mobility of colistin in soils might offer insights into the potential impact of colistin on the emergence and prevalence of resistant bacteria and the ecological environment.

Comparison of Low-Cost Methods for Soil Water Holding Capacity

ABSTRACT The use of cost-effective methods for measurement of WHC is common in underdeveloped and developing countries, but the accuracy of these cost-effective methods compared to the sophisticated and more expensive alternatives is unclear. To compare different WHC measurement methods, 30 random samples of clay loam and sandy clay loam soils of Jhansi, India were used. The methods compared here were: FAO in-situ method (FAO), Keen-Raczkowski box method (KM), funnel method (FM), column method (CM) and pressure plate method (PPA). For WHC measurements the PPA results were comparable to KM and FM methods for sandy clay loam, and KM and FAO methods for clay loam. Therefore, until a reliable method that matches the results of sophisticated analytical methods of soil water measurement is available, different inexpensive analytical methods can be used, but they must be chosen with caution. The findings from this study will facilitate appropriate selection of a suitable method.

Discovery of the Relationship between Distribution and Aflatoxin Production Capacity of Aspergillusspecies and Soil Types in Peanut Planting Areas.

In order to study the relationship between the distribution and aflatoxin production capacity of Aspergillus species and soil types, 35 soil samples were collected from the main peanut planting areas in Xiangyang, which has 19.7 thousand square kilometers and is located in a special area with different soil types. The soil types of peanut planting areas in Xiangyang are mainly sandy loam and clay loam, and most of the soil is acidic, providing unique nature conditions for this study. The results showed that the Aspergillus sp. population in clay loam (9050 cfu/g) was significantly larger than that in sandy loam (3080 cfu/g). The percentage of atoxigenic Aspergillus strains isolated from sandy loam samples was higher than that from clay loam samples, reaching 58.5%. Meanwhile the proportion of high toxin-producing strains from clay loam (39.7%) was much higher than that from sandy loam (7.3%). Under suitable culture conditions, the average aflatoxin production capacity of Aspergillus isolates from clay loam samples (236.97 μg/L) was higher than that of strains from sandy loam samples (80.01 μg/L). The results inferred that under the same regional climate conditions, the density and aflatoxin production capacity of Aspergillus sp. in clay loam soil were significantly higher than that in sandy loam soil. Therefore, peanuts from these planting areas are at a relatively higher risk of contamination by Aspergillus sp. and aflatoxins.

Interactions between Water Evaporation and Surface Cracking in NaCl-Induced Homogeneous Silt Loam and Sand

ABSTRACT The processes of soil cracking with water loss in saline soils are still not well understood. It is of great significances to further understand the mechanism of desiccation cracking in saline-alkali soil and provide guidance for engineering practice in saline-alkali area. Silt loam and sand samples were saturated with NaCl solutions (5, 50, and 100 g/L) and undergone the evaporation tests, during which the water loss and surface cracking parameters were obtained. Results showed that evaporation and crack development influenced each other. The evaporation rate for both sand and silt loam samples saturated by NaCl solution was lower than the reference samples, and decreased as the concentration of NaCl solution increased. In addition, the water content for both two types of samples first rapidly decreased and then entered a stable state during evaporation; however, silt loam soil moisture experienced a “second decline” when surface crack developed rapidly. Compared to the reference sample, NaCl solution inhibited crack development in silt loam, which in turn impeded water evaporation; however, no surface cracks were observed in sand samples. Furthermore, crack area and crack length decreased as the concentration of NaCl solution increased, and higher NaCl concentration resulted in an earlier abrupt increase in crack number followed by a stable state. The present findings reveal that the interaction between water evaporation and surface cracking is shown by soluble NaCl, including the chemical effects on soil particles from free Na+ and the physical effects on soil pores from precipitated NaCl crystals during water loss.

Naked-Eye Detection of 3-Nitro-1,2,4-triazole-5-one at Sub-Femtomolar Levels with Melamine and Unlabeled Au Nanoparticles

In this paper, a simple and rapid nanosensing assay was developed for 3-nitro-1,2,4-triazole-5-one (NTO) exploiting target-directed adsorption by unlabeled gold nanoparticles (AuNPs) and competitive supramolecular association of NTO with melamine (MEL). While AuNPs aggregated in the presence of MEL with a color change from red to blue, AuNPs remained dispersed and retained their original plasmonic red color with the addition of NTO, owing to the hydrogen bonding affinity of the NTO triazole ring to MEL. The concentration of NTO leading to color change could be determined with the naked-eye even at the sub-femtomolar level. Analytical results showed that the absorption ratio (A520nm/A630nm) varied linearly with the logarithm of NTO concentration in the range of 3.08 × 10–16 to 3.08 × 10–12 mol L–1 with a correlation coefficient of 0.9994. The synthesized and resultant AuNPs (in the presence of NTO and/or MEL) were characterized using ultraviolet–visible spectrophotometry, scanning transmission electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and ζ-potential measurements. Possible interferences of various energetic substances in synthetic mixtures containing 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol, hexahydro-1,3,5-trinitro-1,3,5-triazine, and ammonium nitrate, of possible camouflage materials used in passenger belongings such as cationic surfactants (cetyltrimethylammonium bromide and cetylpyridinium chloride), d-(+)-glucose as a representative sugar, acetylsalicylic acid- and paracetamol-based painkiller drugs, and of commonly found soil ions (Cl–, NO3–, SO42–, Ca2+, Mg2+, CuII, FeII/III, and AgI) were also examined. In addition, recovery of NTO was successfully performed from NTO-based melt-cast formulations consisting of mixtures of TNT and NTO. The proposed method was statistically validated against a reference liquid chromatography–tandem mass spectrometry method applied to NTO standards, NTO-contaminated soil, and loam samples.

Interactions between water flow and microplastics in silt loam and loamy sand

AbstractThe threat of microplastics (MPs) intervention in cropland always results in water flow alteration, which is the leading cause behind MP transport and distribution. This study investigated water infiltration and MP transport and distribution on MP‐contaminated silt loam and loamy sand to explore how water flow and MP affect each other and reveal their mechanisms. The results indicated that water infiltration increased as the content of MPs present in the soils increased from 1 to 7% (w/w), which increased the MPs in deeper soil layers. For the silt loam sample, the MP concentration first increased to higher levels at 15–20 cm and then decreased. The MPs with sizes of 0–150 and 150–500 μm were found in excess at 25‐to‐30‐cm and 5‐to‐20‐cm depths, respectively. In the case of the loamy sand sample, the MP concentration gradually increased up to 30‐cm depth, and the MPs with sizes of 0–150 and 150—500 μm were found in excess at 5‐to‐10‐cm and 15‐to‐30‐cm depths, respectively. The increased infiltration was due to the increased hydraulic conductivity resulting from inhibition of soil particle aggregation, increased soil porosity, and strong hydrophobicity of MP particles. The difference in proportions of various MP particle sizes in soil layers was due to the differences in migration ability in pores for various soil samples and MP particle aggregation features.

Impact of soil organic matter on Pu migration in five Lithuanian surface soils

Pu distribution coefficient Kd variation was experimentally determined and examined in natural soil samples considering the type of soil, particle size, pH, the concentration of macroelements and organic matter content. This research was carried out with sand, silty sand, peat, clayey sand and clayey loam samples by applying 236Pu tracer in flow-through column tests. Due to relatively short contact time of 0.5–40 h the tests are considered as have not reached equilibrium state and represent the fast-moving contaminants retardation processes closer to field conditions. Every soil sample was fractionated into two particle size fractions: ≤0.25 mm and 0.25 ÷ 0.5 mm. Analysis revealed that Kd of Pu is higher for the smaller soil particle fraction (≤0.25 mm). The experimental study with 1.6, 4, 6 and 9 pH tracer solution revealed a tendency of elevated Kd when 4 pH and 6 pH solutions were applied, but obtained Kd values were not correlated with initial soil pH due to high buffering capacity of soils. This study shows a very significant influence (r = 0.98) of organic matter content on the Pu distribution coefficient. The Kd of Pu for the fine fraction of peat soil with high organic matter content (67%) reached maximum values of 6597 L/kg and 6200 L/kg when tracer solution was applied of pH = 4 and pH = 6, respectively. In comparison, the minimum Kd value of 3.9 L/kg was obtained for the coarse silty sand fraction with the lowest organic matter content of 1.3% at tracer pH = 1.6. A statistically reliable high correlations of r = 0.95 and 0.94 were also observed between Kd and specific soil elements Mg and Pb content in soils, respectively. The content of Fe in soils was significantly correlated (r = 0.67) with the Kd values of plutonium as well. However, the organic matter content in soils appeared to be the governing factor determining good correlations and causing the highest Kd of Pu values.

Soil moisture level prediction using optical technique and artificial neural network

This research describes the use of an optical system combined with artificial neural network (ANN) for wireless and nondestructive prediction of soil moisture level. The former system comprising of near infrared (NIR) emitters of wavelengths 1200 nm and 1450 nm, and a photodetector for near real time soil moisture measurement in loams and peats holding different amount of water. There were 63 and 90 sets of data from loams and peats, respectively, used in the development of the dual stage-multiclass ANN model, wherein measurement of light attenuation (from nondestructive system) was correlated with percent soil moisture (from destructive gold standard approach) in pre-measurement stage. The result revealed a relatively good performance in the training of the NN with regression, R, of 0.8817 and 0.8881, and satisfactory error performance of 0.7898 and 1.172, for loams and peats, respectively. The testing of the system on 50 new samples of loam and peat showed a considerably high mean accuracy of 92 % for loams while 82 % was observed for peats. This study attributes the poorer performance of the system used on peats to the detection resolution of percent soil moisture, and structure and properties of the corresponding soil. This work concluded that the developed technology may be feasible for use in the future design and improvement of agricultural soil management.

Biogeochemical Modelling of Uranium Immobilization and Aquifer Remediation Strategies Near NCCP Sludge Storage Facilities

Nitrate is a substance which influences the prevailing redox conditions in groundwater, and in turn the behaviour of U. The study of groundwater in an area with low-level radioactive sludge storage facilities has shown their contamination with sulphate and nitrate anions, uranium, and some associated metals. The uranyl ion content in the most contaminated NO3–Cl–SO4–Na borehole is 2000 times higher (1.58 mg/L) than that in the background water. At the same time, assessment of the main physiological groups of microorganisms showed a maximum number of denitrifying and sulphate-reducing bacteria (e.g., Sulfurimonas) in the water from the same borehole. Biogenic factors of radionuclide immobilization on sandy rocks of upper aquifers have been experimentally investigated. Different reduction rates of NO3−, SO42−, Fe(III) and U(VI) with stimulated microbial activity were dependent on the pollution degree. Moreover, 16S rRNA gene analysis of the microbial community after whey addition revealed a significant decrease in microbial diversity and the activation of nonspecific nitrate-reducing bacteria (genera Rhodococcus and Rhodobacter). The second influential factor can be identified as the formation of microbial biofilms on the sandy loam samples, which has a positive effect on U sorption (an increase in Kd value is up to 35%). As PHREEQC physicochemical modelling numerically confirmed, the third most influential factor that drives U mobility is the biogenic-mediated formation of a sulphide redox buffer. This study brings important information, which helps to assess the long-term stability of U in the environment of radioactive sludge storage facilities.

Impact of repeated loads on saline soils of earth roadbed

The constant development of the road network in Uzbekistan, especially in widespread saline soils, necessitates increased attention to road structure strength. Since vehicles differ in weight and speed, it is obvious that the saline soil under the pavement is subjected to successive impacts of a load of different power and application force. Experimental studies to identify the patterns of changes in saline soils' physical and mechanical properties under repeated and short-term loads were conducted on a device specially designed by the authors of this study. The experiments were conducted on samples of sulfate and chloride-sulfate medium-saline heavy silty sandy loam, compacted at optimal moisture content to maximum density. When conducting the experiment, the impact duration of vertical load Рver = 0.15 MPa on the sample was tload = 0.2 sec, and the interval between the loads was 0.5 sec, the frequency of application was f = 1.2 Hz. The number of short-term load applications was recorded using an electric meter installed on the device. After a certain number of short-term cyclic load applications on the sample, its physical and mechanical properties were determined following the requirements of state standards (GOST). The results of the study show that with an increase in the number of cyclic and short-term load impacts on the sample, the following values increase: residual strain, density, and modulus of setting, relative swelling, swelling pressure, ultrasonic transmission rate, coefficient of filtration; while the porosity, coefficient of porosity, soaking, ultimate strength in uniaxial compression, the coefficient of dynamic viscosity, adherence, the angle of internal friction and the modulus of elasticity of soil decrease. It was determined that under the repeated impact of short-term loads in compacted saline soil, residual strains and short-term redistribution of stresses in the contact of soil and salt particles occur, which leads to a change in the physical and mechanical properties of soil.

Alkalinized sewage sludge affects nutrition and growth of common bean cultivated in Ferralsols

A aplicação de lodo de esgoto alcalino em solos agrícolas aumentou, mas as implicações nutricionais para as culturas ainda são pouco exploradas. Com o objetivo de avaliar o efeito do lodo de esgoto alcalinizado na nutrição e crescimento do feijoeiro (Phaseolus vulgaris L.), foi realizado experimento em casa de vegetação com três Latossolos e três tipos de lodo de esgoto. Amostras de Latossolos (texturas franca, muito argilosa e argilosa) foram coletadas em três regiões geologicamente distintas do estado do Paraná, Brasil: arenito, basalto e argilito. Amostras de lodo de esgoto foram estabilizadas com calcário e posteriormente misturadas com as amostras de solo. Lodo de esgoto alcalinizado e calcário foram aplicados aos solos nas taxas correspondentes a 50, 100, 150 e 200% da quantidade necessária para o solo atingir pH 5,5. Aos 67 dias após emergência, foram medidas a altura das plantas, matéria seca da parte aérea e composição elementar das folhas. Em comparação ao calcário, o lodo alcalinizado promoveu maior produção de matéria seca da planta nos solos argilosos. O lodo de esgoto alcalinizado aplicado aos solos resultou em maiores teores de Zn e P na parte aérea da planta do que o calcário, enquanto ambos os corretivos reduziram os teores de K e Mn na parte aérea. A relação Fe/Mn mostrou ser muito efetivo para explicar sintomas foliares que foram observados sob condição de elevada acidez. O lodo alcalinizado apresentou desempenho superior quanto à nutrição e promoção do crescimento do feijoeiro no solo argiloso.

Thermo‐time domain reflectometry to evaluate unsaturated soils contaminated with nonaqueous phase liquids

AbstractSoil and groundwater contamination by nonaqueous phase liquids (NAPLs) has become a serious environmental issue. This study applied the thermo‐time domain reflectometry (TTDR) technique to determine the effects of NAPL contamination on the thermal and electromagnetic properties of unsaturated soils. Furthermore, the applicability of TTDR to determine the NAPL content was evaluated, and a new calibration equation was established to estimate the NAPL saturation level in unsaturated soils. Multiple unsaturated sand and silt loam samples at a constant water content were mixed with various amounts of motor and sunflower seed oils. The TTDR probes were then applied to simultaneously measure the dielectric constant, electrical conductivity, thermal conductivity, and heat capacity. An independent experiment was conducted to compare the NAPL content estimated using the new calibration equation and the known content. The results show that the NAPL content had no effect on the dielectric constant, and the soil dielectric constant maintained a steady value at the same water content, which ranged from 5 to 20 with increasing water content. At a constant water content, the soil electrical conductivity slightly decreased as the NAPL content increased. The soil thermal conductivity generally increased with the addition of NAPLs. There was a linear correlation between the total liquid content in the soil and the volumetric heat capacity. A new calibration equation was established to determine the NAPL saturation in soils from the relationship between the soil saturation, volumetric heat capacity, and water content as measured by time domain reflectometry. Independent validation indicated that the calibration equation was able to provide accurate NAPL saturation data in the laboratory, with a RMSE of 0.042.

Permanganate oxidizable carbon for soil health: Does drying temperature matter?

AbstractSoil health assessments evaluate and monitor the effects of conservation management on soil properties. A popular measurement, permanganate oxidizable carbon (POXC), is routinely included in these assessments. The standard POXC protocol calls for air‐dried soil samples, but commercial laboratories typically dry samples in a forced‐air oven before routine analysis. In order to evaluate if heat would change POXC measurements, we treated soil (52 silty clay loam and 51 sandy loam samples) with oven drying at 45 and 65 °C and compared their POXC values with those from air‐dried samples. We also examined relationships between POXC values and soil organic matter, pH, and electrical conductivity across drying treatments. Drying soil did not substantially change POXC values for either soil texture and did not change the relationships between POXC and other measured soil properties. This work suggests that commercial laboratories could perform POXC analysis on soil samples dried using heat.

The effects of rock fragment content on the erosion processes of spoil heaps: a laboratory scouring experiment with two soils

Spoil heaps on newly engineered landforms create extensive artificially accelerated erosion, especially when there are catchment areas above spoil heaps, erosion caused by runoff will be much greater than that induced by rainfall. This study investigated the erosional characteristics of clay loam and sandy loam spoil heaps and proposed an appropriate hydraulic parameter to simulate the variation in erosion rate. A laboratory scouring experiment was conducted using a soil pan (dimensions 5 m × 1 m × 0.5 m deep) with a discharging arrangement to test four samples of clay loam and sandy loam containing rock fragments (0%, 10%, 20%, and 30%) by mass. The slope of simulated spoil heaps was 53.2% with a discharging inflow rate of 15 L min−1. The rock fragments used were those commonly used in construction works, having a diameter of 2–3 cm and irregular shape. Twenty-four scouring tests for eight treatments with duplication were accomplished in total. Average erosion rates showed a negative linear correlation with rock fragment content in clay spoil heaps (R2 = 0.94) and a positive linear correlation in sandy loam spoil heaps (R2 = 0.92). Rill width evolution of clay loam spoil heaps mainly developed at the early scouring stage (0–15 min), and rills developed even more rapidly during later scouring times (30–60 min) in sandy loam spoil heaps. Grey relational analysis showed that sheer stress and stream power both had higher Grey relational degrees with erosion rate for both soils, regression analysis showed that stream power can efficiently describe the erosional process of clay loam and sandy loam for each rock fragment content, but sheer stress only did well in sandy loam heaps. Adding rock fragments to spoil heaps resulted in significantly opposite effects in the different soils; great attention should be paid to sandy loam spoil heaps due to their more severe erosion with increasing rock fragment content; stream power is an appropriate hydraulic parameter to simulate the soil erosion process of spoil heaps for both soil types.

A case study of a precariously balanced rock, its partially exhumed corestone platform, and encasing saprock and soil

Lying between the Elsinore and San Jacinto faults, ~0.5 km SE of Roundtop, is a tonalitic corestone perched precariously on an exhumed corestone base. Such features are referred to as precariously balanced rocks (PBRs). Cosmogenic 10Be data listed in an online abstract suggest a tentative exhumation age of the PBR near Roundtop at ~35,000 years ago. The absence of PBRs adjacent to the Elsinore and San Jacinto faults implies that they were shaken free from their perches during ground shaking. Alternatively, their absence may reflect a more highly fractured and intensely weathered terrane. Because the weathering histories of PBRs have not been studied previously, we analyzed the texture, clay mineralogy, and geochemistry of the Roundtop PBR to answer several basic questions. Can the characteristics of the regolith that once encased the precariously balanced rock be reconstructed? What chemical processes operated in the regolith prior to exhumation, and are these processes still occurring? Following exhumation, did new fracture development modify the original regolith? To answer these questions, we extracted three ~1 m long cores from the PBR near Roundtop, and collected 23 saprock and 9 pebbly sandy loam samples from a trench excavated near the base of the corestone platform. Plagioclase and biotite alteration, along with the concomitant loss of Ca, Na, Sr, Ba, K, Mg, Mn, Nb, and P mass, are the primary evidence of weathering intensity within the saprock. Additionally, the presence of mostly kaolinite, and lesser quantities of mixed-layer biotite/smectite in the saprock, along with the above observations and data, point to significant fluid/rock interations during saprock development. Subsequent formation of pebbly sandy loam appears to have been accomplished primarily through pedoturbation within the uppermost portions of the underlying already weathered saprock, and produced little additional chemical weathering. Hence, our data support the general idea that Roundtop is an area of weak ground shaking, and that since current exhumation little weathering has affected this PBR locality.

Activity of dehydrogenases in clay soil exposed to quaternary ammonium salts with iodine anion

The aim of the research was to compare the effects of four to quaternary ammonium salts (QAS) with iodine anion: tetramethylammonium iodine [TMA][I], tetraethylammonium iodine [TEA][I], tetrapropylammonium iodine [TEA][I], tetrabutylammonium iodine [TBA][I]. The experiment was carried out on sandy clay loam samples with organic carbon content of 33.82 g·kg -1 , and pH in 1 M KCl 7.13. QAS were added to soil at the dosages of: 0, 10, 100, and 1000 mg · kg -1 . Activity of dehydrogenases was assayed on days: 1, 14, 35, and 70. Obtained results have shown that the soil treatment with quaternary ammonium salts with iodine anion caused decrease in activity of dehydrogenases. This inhibition increased with increase of QAS dosages, and increase with alkyl chains in cations. Analysis of variance η 2 indicated, that type of QAS had the biggest impact on formation of activity of dehydrogenases in soil.

Investigations of the regularity of the formation of a dip over the mine

The article presents the results of physical simulation of the formation of a dip over the mine workings. For this purpose, similarity criteria are substantiated and an experimental stand is developed. On samples of quaternary loam and clay it is proved that the velocity of the motion of the dip depends nonlinearly on the moisture content and exponentially damps in time.