scholarly journals Sulfate sorption measured by a buffering index over a range of properties of soils from south Western Australia

Soil Research ◽  
2020 ◽  
Vol 58 (7) ◽  
pp. 651 ◽  
Author(s):  
G. C. Anderson
Keyword(s):  
Plant Uptake ◽  
Soil Layer ◽  
Equilibrium Concentration ◽  
Sulfate Solution ◽  
Soil Samples ◽  
Freundlich Equation ◽  
Soil Sulfur ◽  
Sulfate Leaching ◽  
Adsorption Curve ◽  
Sorption Curve

Sulfate sorption by the soil affects the rate of sulfate leaching, which impacts on the availability of soil sulfate for plant uptake. In Australia, plant-available sulfur is measured using 0.25 M KCl heated for 3 h at 40°C to extract soil sulfur (SKCl40). This paper describes a technique referred to as a sulfate buffering index (SBI), which provides a measurement of sulfate sorption. SBI when combined with the estimates of the q and b parameters of the Freundlich equation, can be used to define a sorption curve. The equation is S = acb – q; where S is the amount of sulfate adsorbed (mg S kg–1), c is the equilibrium concentration of sulfate measured in solution (mg S L–1) and a, b and q are coefficients that describe the soil sulfate sorption curve. Coefficients S and c were measured using six sulfate solution concentrations ranging from 0 to 250 mg S kg–1. The adsorption curve was fitted using the modified Freundlich equation including setting of b = 0.41 and q = SKCl40 using recently collected soil samples. The modified Freundlich a coefficient or SBI was calculated as SBI = (S + SKCl40)/c0.41; where S and c were determined using 50 mg S kg–1 of added sulfate. The SBI ranged within 1–40. The SKCl40 was related to SBI below a depth of 10 cm (r2 = 0.71) but not for the 0–10 cm soil layer where S sorption was minimal.

Bacterial influence on the formation of hematite: implications for Martian dormant life

2021 ◽  
pp. 1-15
Author(s):  
Sudeera Wickramarathna ◽  
Rohana Chandrajith ◽  
Atula Senaratne ◽  
Varun Paul ◽  
Padmanava Dash ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Soil Layer ◽  
Soil Samples ◽  
Mineral Weathering ◽  
Compositional Variation ◽  
Rrna Gene ◽  
Potential Candidate ◽  
Metabolic Processes ◽  
Extraterrestrial Life ◽  
X Ray

Abstract Previous exploration missions have revealed Mars as a potential candidate for the existence of extraterrestrial life. If life could have existed beneath the Martian subsurface, biosignatures would have been preserved in iron-rich minerals. Prior investigations of terrestrial biosignatures and metabolic processes of geological analogues would be beneficial for identifying past metabolic processes on Mars, particularly morphological and chemical signatures indicative of past life, where biological components could potentially be denatured following continued exposure to extreme conditions. The objective of the research was to find potential implications for Martian subsurface life by characterizing morphological, mineralogical and microbial signatures of hematite deposits, both hematite rock and related soil samples, collected from Highland Complex of Sri Lanka. Rock samples examined through scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy. Analysis showed globular and spherical growth layers nucleated by bacteria. EDX results showed a higher iron to oxygen ratio in nuclei colonies compared to growth layers, which indicated a compositional variation due to microbial interaction. X-ray diffraction analysis of the hematite samples revealed variations in chemical composition along the vertical soil profile, with the top surface soil layer being particularly enriched with Fe2O3, suggesting internal dissolution of hematite through weathering. Furthermore, inductively coupled plasma-mass spectrometry analyses carried out on both rock and soil samples showed a possible indication of microbially induced mineral-weathering, particularly release of trapped trace metals in the parent rock. Microbial diversity analysis using 16S rRNA gene sequencing revealed that the rock sample was dominated by Actinobacteria and Proteobacteria, specifically, members of iron-metabolizing bacterial genera, including Mycobacterium, Arthrobacter, Amycolatopsis, Nocardia and Pedomicrobium. These results suggest that morphological and biogeochemical clues derived from studying the role of bacterial activity in hematite weathering and precipitation processes can be implemented as potential comparative tools to interpret similar processes that could have occurred on early Mars.

Study on the Selecting Principle of Test Soil Samples in Nonlinear Seismic Response Analysis of Stratified Site

2012 ◽  
Vol 170-173 ◽  
pp. 984-993
Author(s):  
Xue Liang Chen ◽  
Meng Tan Gao ◽  
Tie Fei Li ◽  
Zhao Lun Yan
Keyword(s):  
Soil Sample ◽  
Seismic Response ◽  
Soil Layer ◽  
Soil Samples ◽  
Response Analysis ◽  
Soil Test ◽  
Calculation Error ◽  
Iron And Steel ◽  
Nonlinear Seismic Response ◽  
Test Soil

Soil dynamic nonlinear experimental results have significant impacts on the seismic response of engineering site, but how reasonable and effective to select soil samples for soil test, there is no good solution. Using detailed drilling velocity, density data, and rich soil test data of Shanxi Linfen Iron and Steel Hospital engineering site, four models are established and are analyzed for this problem. The results showed that: less than 3 meters of soil layer, each layer select one soil sample, for the thick soil layer, the rules of selecting one soil sample about every 3m thickness for the soil test, are recommended. If selecting one soil sample about every 5m~6m thickness for the thick soil layer, the calculation error is about ±10%.

Stable Isotope Analysis of Water Uptake Sources of Primary Forests in the Central Yunnan Karst Plateau

2013 ◽  
Vol 864-867 ◽  
pp. 2455-2458
Author(s):  
Tao Fan ◽  
Jie Li
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Plant Uptake ◽  
Rock Fracture ◽  
Isotope Analysis ◽  
Soil Layer ◽  
Water Sources ◽  
Soil Layers ◽  
Cyclobalanopsis Glaucoides ◽  
Primary Forests

Ecosystems in the central of Yunnan karst plateau are very fragile due to thin soil layer and intensive infiltration capacity of rock fracture, which result in a very limited amount of water storage for plant uptake. Water retention in the soil zone and shallow fractured rock zone (subcutaneous) is a key factor for plant growth. Distinction of water sources taken by karst plants is a challenging task for botanists and hydrologists but is needed for ecosystem management. In this study, stable isotope analysis was used to investigate water sources for Cyclobalanopsis glaucoides primary forests at Shilin Geopark in Bajiang vally, central Yunnan of China. Proportions of water sources for plant uptake were determined by the δD and δ18O values of plant stem water, and water taken from soil layers and the subcutaneous zone. The analysis reveals that water was mainly taken from the soil layers and to less degree the subcutaneous zone as well. In dry seasons with scarce precipitation, plants in the primary forest were prone to take more water from subcutaneous zone and deeper layer of soil. Different species had different water use strategies, Cyclobalanopsis glaucoides took a larger proportional water from the deeper layer of soil, suggesting its deeper roots and wider range of shallower roots. However, Olea yunnanensis and Pistacia weinmannifolia extracted more percentage of water from the deeper soil water and subcutaneous water because of its deeper roots.

scholarly journals Sugarcane straw decomposition and carbon balance as a function of initial biomass and vinasse addition to soil surface

Bragantia ◽  
2017 ◽  
Vol 76 (1) ◽  
pp. 135-144 ◽  
Author(s):  
Carina Sayuri Yamaguchi ◽  
Nilza Patrícia Ramos ◽  
Cristina Silva Carvalho ◽  
Adriana Marlene Moreno Pires ◽  
Cristiano Alberto de Andrade
Keyword(s):  
Soil Carbon ◽  
Carbon Concentration ◽  
Decomposition Rate ◽  
Soil Layer ◽  
Soil Surface ◽  
Soil Samples ◽  
Water Retention Capacity ◽  
Straw Decomposition ◽  
Retention Capacity ◽  
Sugarcane Straw

ABSTRACT The objective of this study was to evaluate sugarcane straw decomposition and the potential of increasing soil carbon as a function of the initial biomass and vinasse addition to soil surface. The experimente consisted of incubation (240 days, in the dark, humidity equivalent to 70% of soil water retention capacity and average temperature of 28 °C) of Oxisol soil samples (0-20 cm soil layer) with straw added to soil surface at rates of 2; 4; 8; 16 and 24 t∙ha−1 and with or without vinasse addition (200 m3∙ha-1). The following variables were determined: released C-CO2, remaining straw dry matter, carbon straw and soil carbon concentration. The added biomass did not influence straw decomposition rate, but vinasse treatments provided rates between 70 and 94% compared to 68 to 75% for the ones without vinasse. The straw (16 and 24 t∙ha−1) decomposition rate increased between 14 and 35% due to vinasse addition, but the same behavior was not observed for released C-CO2. This result was explained by the twofold increase of soil carbon concentration, estimated by mass balance and confirmed analytically by the carbon concentration of soil samples. It was concluded that sugarcane straw decomposition, under no limiting conditions of humidity and temperature, did not depend on biomass initially added and that vinasse addition accelerated straw decomposition and potentialized carbon input into the soil.

scholarly journals Transformation of organic carbon in alluvial soils under different land uses

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
Alvyra Šlepetienė ◽  
Kazimiež Duchovski ◽  
Jonas Volungevičius
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Arable Land ◽  
Soil Layer ◽  
Soil Samples ◽  
Plant Residues ◽  
Land Uses ◽  
Forest Land ◽  
Alluvial Deposits

The aim of this study – to evaluate the status of organic carbon (OC) under different land uses of soils formed in alluvial deposits. The soil samples were collected from 0–10, 10–20 and 20–30 cm depths in three field replicates.Three land uses were investigated: arable land, grassland and forest. The experimental site is situated near Surviliškis, Kėdainiai District (55°26′08.37′′N, 24°02′27.75′′Y) in Central Lowland of Lithuania. A total of 27 soil samples, collected from 0–10, 10–20 and 20–30 cm depths in three field replicates, were analysed for OC. The samples were prepared for analysis by removing plant residues, grinding and sieving through a 0.25 mm sieve. For all land uses, the highest content of OC was found in the upper 0–10 cm soil layer of the soil, with the highest values found in the forest land use. Fast-growing deciduous trees are an effective means to increase the content of OC in alluvial soil, especially in the 0–10 cm layer. The distribution of OC in the soil layers depended on the land use. Grassland and forest land uses allow OC to be preserved throughout the 0–30 cm layer, with less OC differentiation than in arable land. This could be attributed to the specificities of organic matter accumulation and degradation in different land uses. Not only the amount of labile organic carbon (similar to total organic carbon) was highest (0.392 g kg–1) in forest soil in the 0–10 cm layer, it also had a higher relative share in the total organic carbon (2.9%) than in other land uses – arable land and grassland (2.3–2.4%).

scholarly journals Validation of a method for in situ determination of 137Cs soil contamination density in kitchen gardens using the portable spectrometer-dosimeter MKS AT6101D

2021 ◽  
Vol 14 (2) ◽  
pp. 56-65
Author(s):  
V. P. Ramzaev ◽  
A. N. Barkovsky ◽  
A. A. Bratilova
Keyword(s):  
Soil Contamination ◽  
Chernobyl Accident ◽  
Soil Layer ◽  
Soil Samples ◽  
Ex Situ ◽  
Measuring Device ◽  
Kitchen Garden ◽  
In Situ Method ◽  
Kitchen Gardens

The collection of representative soil samples in the territory of settlements and subsequent measurements of the content of radionuclides in these samples under laboratory conditions (the so-called “ex situ method”) is a generally accepted technology for determining the density of soil contamination with 137Cs in the populated areas contaminated due to the Chernobyl accident. Recently, as a supplement or alternative to the ex situ method, researchers are developing field (in situ) gamma-spectrometry methods. These methods allow determining the density of soil contamination with 137Cs directly on site, without soil sampling and laboratory analysis. At the same time, the in situ methodology has several limitations, the most important of which is a lack of generally recognized metrological basis for measurements and interpretation of results. Hence, before using a particular technique and measuring device for carrying out large-scale in situ measurements, it is necessary to validate (to assess the suitability) of the selected in situ method using an established ex situ method. The aim of this study was to validate the method for determining the density of 137Cs soil contamination in kitchen gardens using the MKS AT6101D spectrometer-dosimeter in situ. The method was recently presented by a Russian-Swedish-Belarusian group of researchers in an article published in the Journal of Environmental Radioactivity (https://doi.org/10.1016/j.jenvrad.2021.106562). To validate this method, we selected 10 representative kitchen garden plots. The plots were located in six settlements of the Bryansk region in Russia. The territory of the settlements had been heavily contaminated with 137Cs as a result of the Chernobyl accident: the officially established levels of the density of soil contamination by 137Cs ranged from 111 to 511 kBq/m2 in 2017. Field gamma-ray spectra were recorded at a height of 1 m above the ground in the center of kitchen garden plots using the MKS AT6101D device. The measurement duration was in the range of 1207–1801 s (the mean value = 1383 s). Samples of soil in the kitchen gardens were taken layer by layer (with a step of 5 cm) to a depth of 20 cm using a demountable cylindrical sampler. The 137Cs content in each soil layer was determined in the laboratory using a stationary semiconductor gamma spectrometer. The values of the 137Cs contamination density of the sampled soils ranged from 77 to 548 kBq/m2. It was found that the results of the ex situ analyzes of soil samples were in a good agreement with the contamination density values obtained with the in situ method. On average, the difference between two methodologies was 7% (a maximum of 20%). The results of the study confirm that the method proposed by the international group is suitable for determining the density of soil contamination by 137Cs in kitchen gardens in remote period after the Chernobyl accident.

scholarly journals Persistence of water repellency in coarse-textured soils under various types of forests in NW Spain

2019 ◽  
Vol 67 (2) ◽  
pp. 129-134 ◽  
Author(s):  
Elena Benito ◽  
Eufemia Varela ◽  
María Rodríguez-Alleres
Keyword(s):  
Eucalyptus Globulus ◽  
Water Drop ◽  
Soil Layer ◽  
Water Repellency ◽  
Soil Samples ◽  
Penetration Test ◽  
Dry Period ◽  
Nw Spain ◽  
Soil Water Repellency ◽  
Very High

Abstract The primary purpose of this work was to assess the persistence of water repellency in the surface horizon of coarse-textured soils under natural Quercus robur ecosystems, and Pinus pinaster and Eucalyptus globulus plantations, in the northwest of the Iberian Peninsula. Water repellency was determined by applying the water drop penetration test (WDPT) to soil samples collected from variable depths (0–40 cm). Measurements were made on field-moist samples obtained at the end of the dry period and on samples dried at 25ºC in the air. All soils exhibited very high (severe to extreme) water repellency in the topmost soil layer (0–5 cm) but no significant differences among the three plant species studied. Extreme persistence was observed down to 20 cm in the soils under eucalyptus and down to 10 cm in those under pine. The soils under oak were those exhibiting the highest variability in water repellency and the greatest decrease in it with increasing depth (especially in relation to soils under eucalyptus). Water repellency exhibited significant positive correlation with the C content and C/N ratio of the soils. Soil water repellency was similar in the air-dried samples and field-moist samples.

scholarly journals The effects of humic substances on DNA isolation from soils

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9378
Author(s):  
Ewa Wnuk ◽  
Adam Waśko ◽  
Anna Walkiewicz ◽  
Piotr Bartmiński ◽  
Romualda Bejger ◽  
...  
Keyword(s):  
Humic Substances ◽  
Dna Isolation ◽  
Arable Land ◽  
Soil Layer ◽  
Soil Samples ◽  
Total Carbon ◽  
High Concentration ◽  
Soil Dna ◽  
Total Carbon Content ◽  
Direct Cell

Background Humic substances (HS) are compounds with a complicated structure, present in the humus soil layer, water, lake sediments, peat, brown coal and shales. Due to their similar physicochemical properties to DNA, they may have an adverse effect on the subsequent use of the isolated material. The main aim of this research was to examine the effect of HS on DNA isolation depending on the soil type and land use, taking into account the spectroscopic full characteristics of HS fractions. Methods The research was conducted on eight types of soil sample. Soils represented the most important Soil Reference Groups for temperate climates: Fluvisols, Regosols, Cambisols, Arenosols, Histosols and Luvisols. Soil samples were also collected from areas diversified in terms of use: arable land, grassland and forest. The extraction of HS fractions was performed using the procedure recommended by the International HS Society. The fractional composition of HS was characterized by UV–Vis and fluorescence methods. Soil DNA is extracted by direct cell lysis in the using a CTAB-based method with a commonly-used commercial soil DNA isolation kit. The basis for assessing the quantity and quality of extracted DNA was the Polymerase chain reaction (PCR) reaction since the analysis of soil DNA often relies on the use of PCR to study soil microorganisms. Results Based on the results, it can be concluded that in the presence of a high concentration of HS, the isolated DNA was low quality and the additional purification procedure was necessary. Despite the differentiation of the internal structure of HS fractions, the decisive factor in the efficiency of DNA isolation from soil samples was the total carbon content in HS. Reduced DNA yields can significantly constrain PCR detection limits to levels inadequate for metagenomic analysis, especially from humus-rich soils.

scholarly journals ESTUDO COMPARATIVO DE MÉTODOS PARA A DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA NO SOLO

Irriga ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 193-207 ◽  
Author(s):  
Patricia Dos Santos Nascimento ◽  
Luis Henrique Bassoi ◽  
Vital Pedro da Silva Paz ◽  
Carlos Manoel Pedro Vaz ◽  
João De Mendonça Naime ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Soil Layer ◽  
Irrigation Scheduling ◽  
Soil Samples ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Disturbed Soil

A curva de retenção de água no solo pode ser estimada por diversos métodos, e alguns deles demandam maior tempo para a sua determinação. Assim, o objetivo desse trabalho foi a comparação da curva de retenção de água no solo, determinada pelos métodos de Arya & Paris, câmara de Richards e centrífuga, em um Neossolo Quartzarênico em Petrolina - PE. Nas camadas de 0,00-0,20, 0,20-0,40 e 0,40-0,60 m de profundidade, foram coletadas amostras deformadas em 3 pontos de uma área cultivada com videiras irrigadas, as quais foram homogeneizadas por camada, formando assim uma amostra composta para cada camada; em seguida, tais amostras foram subdividas em três subamostras e cada uma foi encaminhada para a determinação da curva de retenção de água no solo pelos métodos testados. Os resultados obtidos pelo método de Arya & Paris não apresentaram correspondência com os obtidos pelos métodos da centrífuga e da câmara de Richards. No entanto, o desenvolvimento de calibrações específicas do método de Arya & Paris para os solos irrigados do Submédio São Francisco é recomendada, tanto pela possibilidade de uso da curva de retenção de água no solo para o manejo de irrigação, como pelo potencial do método quanto à determinação rápida.   UNITERMOS: retenção de água do solo, analisador granulométrico, método.     NASCIMENTO, P. dos S.; BASSOI, L. H.; PAZ, V. P. da S.; VAZ, C. M. P.; NAIME, J. de M.; MANIERI, J. M. COMPARATIVE STUDY OF DETERMINING METHODS OF SOIL WATER RETENTION CURVE     2 ABSTRACT   Soil water retention curve can be estimated by different methods, and some of them are time consuming. Hence, this research aimed to determine and compare the soil water retention curve, obtained by the methods proposed by Arya & Paris, Richards (pressure membrane apparatus) and centrifuge, of a Typic Quartzipisamment from Petrolina, State of Pernambuco, Brazil. To determine the soil water retention curve in the layers of 0.00-0.20; 0.20-0.40 and 0.40-0.60 m depths, disturbed soil samples were collected in three points of an irrigated vineyard area. The disturbed soil samples were homogenized by layer, thus forming a composed sample for each soil layer. These samples were subdivided into three sub samples, and each one was used to determination of soil water retention curve by the methods tested. The results from method proposed by Arya & Paris did not present similarity with those obtained by Richards´chamber and centrifuge methods. Nevertheless, the development of specific calibration to irrigated soils from Lower-middle São Francisco region is recommended due to the application of soil water retention curve to irrigation scheduling as well as the quickness of the method.   KEYWORDS: soil water retention, granulometry analyzer, method.  

scholarly journals Soil Disintegration Characteristics of Collapsed Walls and Influencing Factors in Southern China

2018 ◽  
Vol 10 (1) ◽  
pp. 797-806
Author(s):  
Hongyi Zhou ◽  
Huixia Li
Keyword(s):  
Water Content ◽  
Correlation Coefficient ◽  
Sandy Soil ◽  
Soil Layer ◽  
Chemical Properties ◽  
Soil Samples ◽  
Red Soil ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Collapsed walls cause collapsed mounds, and the disintegration characteristics of collapsed walls are thus closely linked with the occurrence of collapsed mounds. The current study examines the disintegration characteristics and the physical and chemical properties of collapsed walls. A multilevel analysis was conducted by obtaining soil samples from four layers of a collapsed wall. The results showed that 1) the physical and chemical properties of the soil samples (red soil layer, sandy soil layer, debris layer, gravel and eluvial breccia) are closely related to the weathering degree of the crust; 2) gravel and eluvial breccia disintegrated in the shortest time, whereas red soil exhibited the slowest disintegration in the vertical section of the collapsed wall. The order of the disintegrating ratio of the layers is as follows: red soil layer < sandy soil layer < debris layer < gravel and eluvial breccia. Initial water content significantly influenced the disintegration ratio of the red soil layer and sandy soil layer, whereas its effect on the debris layer and gravel eluvial breccia is minimal; and 3) most of the physical and chemical properties of the collapsed wall are significantly correlated with the disintegration ratio of the soil sample. The following physical and chemical properties, which are positively correlated with the disintegration ratio, are arranged based on highest to lowest correlation coefficient: sand content, MgO, natural water content, K2O, CaO, exchangeable sodium, pH, porosity, Na2O, and cation exchange capacity. The following physical and chemical properties, which are negatively correlated with the disintegration ratio, are organized based on highest to lowest correlation coefficient: cosmid, Fe2O3, silt particle, Al2O3, TiO2, SiO2, organic matter, free iron oxide, and free alumina. Only exchangeable calcium, saturated water content, specific gravity of soil particles, and dry density of soil particles are significantly correlated with the disintegration ratio. The correlation coefficient indicates that the disintegration ratio and soil structure, as well as the chemical content of clay minerals, are closely correlated. The study helps explain the mechanism of wall collapse and provides references for developing protective measures against erosion.

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