Transport and deposition of Bacillus subtilis through an intact soil column

Soil Research ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 695 ◽  
Author(s):  
Guangming Jiang ◽  
Mike J. Noonan ◽  
Graeme D. Buchan ◽  
Neil Smith
Keyword(s):  
Bacillus Subtilis ◽  
Pore Size ◽  
Unsaturated Soils ◽  
Soil Column ◽  
Breakthrough Curves ◽  
Size Exclusion ◽  
Chemical Tracer ◽  
Pore Size Exclusion ◽  
Unsaturated Flows ◽  
Intact Soil

Bacterial transport in unsaturated soils is much less well understood than in saturated conditions, especially for intact soils. This paper aims to investigate the fate and transport of bacteria in intact soils with different water saturations, and particularly the effect of low suction (and hence removal of water flow in the largest macropores). An intact soil column (0.50 m diameter by 0.70 m depth) with a tension infiltrometer was used to investigate the transport and deposition of Bacillus subtilis endospores (i.e. dormant and persistent bacteria) during saturated and unsaturated flows. Soil porosity and pore size distribution were measured. Porosity decreased with depth and macropores were concentrated in the topsoil. Three tensiometers and a temperature sensor were installed along the soil column to monitor matric suction and temperature. Breakthrough curves for bacteria and chemical tracer Br– at 0 and 0.5 kPa suction were obtained during the 3-month leaching experiment. Bacterial breakthrough occurred earlier than the inert chemical tracer, which is consistent with effects of pore size exclusion. Also, saturated flow gave a significantly higher concentration and recovery ratio of leached bacteria, i.e. 51% v. 0.88%. Recovery of Br– in leachate at both suctions reached >85%. The column was destructively sampled for deposited endospores at the completion of leaching. Bacterial deposition was concentrated in the top 0.10 m, then decreased abruptly and was relatively constant with column depth, although showing some irregularity at the bottom of the column.

scholarly journals Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil

2019 ◽  
Vol 11 (23) ◽  
pp. 6608
Author(s):  
Ibrahim ◽  
Awad ◽  
Al-Farraj ◽  
Al-Turki
Keyword(s):  
Flow Rate ◽  
Sandy Soil ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Soil Column ◽  
Relative Concentration ◽  
Methyl Cellulose ◽  
Maximum Flow ◽  
Breakthrough Curves ◽  
Zero Valent Iron

Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min-1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min-1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency.

Leaching of Total Phosphorus in Greenhouse Soil in Relation to Soil Fertility and Fertilizer Application

2011 ◽  
Vol 183-185 ◽  
pp. 1100-1104
Author(s):  
Lu Fei ◽  
Xin Chen ◽  
Mu Qiu Zhao ◽  
Ya Jie Zhao ◽  
Yi Shi ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Soil Column ◽  
Fertilizer Application ◽  
Chemical Fertilizer ◽  
High Fertility ◽  
Fertility Level ◽  
Leaching Loss ◽  
Water Eutrophication ◽  
Intact Soil ◽  
Total P

Inappropriate applications of phosphorus (P) in agricultural production lead to the leaching loss of P, which subsequently contributes to the eutrophication of water bodies. A leaching experiment using unsaturated intact soil columns was conducted to study the influence of fertilizer application on leaching of phosphorus in a gley meadow soil at different fertility levels (low-, medium and high fertility levels). The soil column at each fertility level received three fertilization treatments (control [CK], manure [M] and chemical fertilizer [F]). The results indicated that the leaching loss of total P (TP) from the soil column was induced by the P input from either manure or chemical fertilizer application, and the extent of leaching loss of P was also positively related to the soil fertility level. In addition, the TP concentrations in the leachates from all fertilization treatments exceeded the critical value for water eutrophication (0.02 mg P/L). This suggests that applications of manure and chemical fertilizer at proper rates with close consideration of the soil fertility level are essential to reduce the leaching loss of TP to the environment.

scholarly journals Quantifying Size Exclusion by Diffusion NMR: A Versatile Method to Measure Pore Access and Pore Size

2018 ◽  
Vol 90 (19) ◽  
pp. 11431-11438 ◽  
Author(s):  
Fredrik Elwinger ◽  
Jonny Wernersson ◽  
István Furó
Keyword(s):  
Pore Size ◽  
Size Exclusion ◽  
Diffusion Nmr

scholarly journals Fractionation of Block Copolymers for Pore Size Control and Reduced Dispersity in Mesoporous Inorganic Thin Films

2020 ◽  
Author(s):  
Alberto Alvarez Fernandez ◽  
Barry Reid ◽  
Jugal Suthar ◽  
Swan Choy ◽  
Maximiliano Jesus Jara Fornerod ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Pore Size ◽  
Protective Coatings ◽  
Size Control ◽  
Size Exclusion ◽  
Porous Network ◽  
Chromatographic Fractionation ◽  
Inorganic Thin Films ◽  
Pore Size Control

Mesoporous inorganic thin films are promising materials architectures for a variety of applications, including sensing, catalysis, protective coatings, energy generation and storage. In many cases, precise control over a bicontinuous porous network on the 10-nm length scale is crucial for their operation. A particularly promising route for structure formation utilizes block copolymer (BCP) micelles in solution as sacrificial structure-directing agents for the co-assembly of inorganic precursors. This method offers pore size control via the molecular weight of the pore forming block and is compatible with broad materials library. On the other hand, the molecular weight dependence impedes continuous pore tuning and the intrinsic polymer dispersity presents challenges to the pore size homogeneity. To this end, we demonstrate how chromatographic fractionation of BCPs provides a powerful method to control the pore size and dispersity of the resulting mesoporous thin films. We apply a semi-preparative size exclusion chromatographic fractionation to a polydisperse poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) BCP obtained from scaled-up synthesis. The isolation of BCP fractions with distinct molecular weight and narrowed dispersity allowed us to not only tune the characteristic pore size from 9.1±1.5 to 14.1±2.1 nm with the identical BCP source material, but also significantly reduce the pore size dispersity compared to the non-fractionated BCP. Our findings offer a route to obtain a library of monodisperse BCPs from a polydisperse feedstock and provide important insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity.

scholarly journals Study on Movement of Water and Salt through Soil Column and Utilization of Hydrus-1D Program to Simulate Five Scenarios of Crop Production in Salt Affected Paddy Soil

2015 ◽  
Vol 10 (1) ◽  
pp. 139
Author(s):  
Panom Chaiyasit ◽  
Piya Duangpatra ◽  
Visoot Verasan ◽  
Varawoot Vudhivanich
Keyword(s):  
Solute Transport ◽  
Bulk Density ◽  
Paddy Soil ◽  
Mung Bean ◽  
Soil Column ◽  
Breakthrough Curves ◽  
Pedotransfer Functions ◽  
Hydraulic Parameters ◽  
Transport Parameters ◽  
Hydrus 1D

<p class="zhengwen"><span lang="EN-GB">An experiment was conducted on the purpose to study movement of water and salt through soil column. Salt-affected paddy soil was assessed for its relevant transport parameters consisting of the hydraulic and the solute transport parameters. The hydraulic parameters included soil hydraulic conductivity (K<sub>s</sub>) and the van Genuchten’s parameters (θ<sub>s</sub>, θ<sub>r</sub>, α, and n). In this experiment the solute transport parameters was referred to the coefficient of Langmuir’s isotherm which consisted of k<sub>d</sub> and η. Experience showed that hydraulic parameters were sensitive to changes of soil bulk density (ρ<sub>b</sub>). Therefore pedotransfer functions describing the relations between these parameters with ρ<sub>b</sub> were established. Straight line functions were found for θ<sub>s</sub> and n, exponential functions were found for α and K<sub>s</sub>, and logarithmic function was found for θ<sub>r</sub>. Packing the soil in the physical column inevitably caused horizontal differentiation of different ρ<sub>b</sub>. Bulk density of each layer was estimated by analysis of water flow through soil column at steady-state. Then ρ<sub>b</sub> of each layer was calculated from the relation K<sub>s</sub> (ρ<sub>b</sub>). After the ρ<sub>b</sub> was known the van Genuchten’s parameters were calculated from the pedotransfer functions. A physical column of 4 inches diameter and 50 cm length was constructed. Sodium chloride solution EC 6 dS/m was fed on soil surface during the process of salinization and the feeding solution was changed to fresh water during the process of desalinization. Breakthrough solution was analyzed for Na concentration and the breakthrough curves were constructed. The relevant parameters as well as initial and boundary conditions were fed into Hydrus-1D on the purpose to simulate the breakthrough curves. Statistical comparison results using t-test and RMSE suggested that Hydrus-1D could be used successfully to monitor transport of water and salt through soil column.</span></p><p class="zhengwen"><span lang="EN-GB">Five scenarios concerning water and solute transport through soil profile under rice and mung bean cropping were simulated using Hydrus-1D. Simulation results suggested that continuous flooding was the most efficient way to leach soluble salts down to ground water. Wet/dry irrigation scheme for rice production could drain salts only when rice crop was in the first period of growth where crop water uptake was small. During later stages of growth concentration profile of Na remained almost unchange indicating negligible downward movement of salts. Leaving the soil to dry naturally during the dry season caused upward accumulation of salt to the degree smaller than cultivating mung bean since water content and hence the diffusion coefficient of the soil were higher and more favorable for upward salt diffusion than in the former case. Inserting the capillary rise hindering soil layer underneath mung bean root zone was found to retard upward diffusion of salt to the degree comparable to leaving the soil to dry naturally.</span></p>

Unsaturated hydraulic conductivity of vineyard soils with high rock fragment content in the Mosel area, Germany

2021 ◽  
Author(s):  
Selina Walle ◽  
Thomas Iserloh ◽  
Manuel Seeger
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Unsaturated Soils ◽  
Hydrological Cycle ◽  
Calculated Data ◽  
Rock Fragment ◽  
Unsaturated Hydraulic Conductivity ◽  
Significant Difference

&lt;p&gt;The study deals with the unsaturated hydraulic conductivity of soils within the scope of the Diverfarming-Project, funded by the EU commission (Horizon 2020 grant agreement no 728003). For this reason, the field work took place in the examined vineyard of the Wawerner Jesuitenberg near Kanzem in the Saar-Mosel valley (Rhineland-Palatinate, Germany). The mentioned parameter is one of the most important specific factors of the hydrological cycle to characterize soil hydraulic properties in the unsaturated soil zone. A mini disc infiltrometer was used to measure the conductivity values at different suctions. The purpose of this study is to determine the plausibility of the fundamentals and the analytical expression of the unsaturated conductivity models in a nearly skeletal soil of schist. In this regard, the mathematical expressions of Mualem (1976), van Genuchten (1980) and Zhang (1997) are focused on calculating the unsaturated hydraulic conductivity. The two variables &amp;#945; and n are analysed in order to better compare between literature specifications and the explicit calculated data of the vineyard&amp;#8217;s soil. As a result, the various developments of &amp;#945; are similar thus the significant difference is based on the value of n. Nevertheless, in consideration of these frame conditions the models represent a suitable mathematical expression of the unsaturated hydraulic conductivity. Furthermore, a range of parameters affecting this conductivity is analysed, particularly with regard to the applied variable soil and cultivation management under the grapevines in the vineyard. Also, the rock fragment cover and the pore size distribution are taken into account. In this context the soil compaction and modified pore size distribution in the wheel tracks stand out due to salient unsaturated hydraulic conductivities at higher tensions. In particular, the stone cover of the contact surface influence the characteristics of the analysed conductivity. Additionally, the connection of stone cover, management and pore size distribution creates a mixture of affected parameters of the unsaturated hydraulic conductivity.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Mualem, Y.: A new model for predicting the hydraulic conductivity of unsaturated porous media, Water Resour. Res, 12, 513&amp;#8211;522, https://doi.org/10.1029/WR012i003p00513, 1976.&lt;/p&gt;&lt;p&gt;Van Genuchten, M.T.: A Closed-form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils, Soil Sci. Soc. Am. J., 44, 892&amp;#8211;898, https://doi.org/10.2136/sssaj1980.03615995004400050002x, 1980.&lt;/p&gt;&lt;p&gt;Zhang, R.: Determination of Soil Sorptivity and Hydraulic Conductivity from the Disk Infiltrometer, Soil Sci. Soc. Am. J., 61, 1024&amp;#8211;1030, https://doi.org/10.2136/sssaj1997.03615995006100040005x, 1997.&lt;/p&gt;

scholarly journals Crystal structure of IspF from Bacillus subtilis and absence of protein complex assembly amongst IspD/IspE/IspF enzymes in the MEP pathway

2018 ◽  
Vol 38 (1) ◽  
Author(s):  
Zhongchuan Liu ◽  
Yun Jin ◽  
Weifeng Liu ◽  
Yong Tao ◽  
Ganggang Wang
Keyword(s):  
Bacillus Subtilis ◽  
Protein Complex ◽  
Isoprenoid Biosynthesis ◽  
Mep Pathway ◽  
Size Exclusion ◽  
Complex Assembly ◽  
Exclusion Chromatography ◽  
Key Enzyme ◽  
Accessible Surface ◽  
Protein Complex Assembly

2-C-Methyl-d-erythritol 2,4-cyclodiphosphate synthase (IspF) is a key enzyme in the 2-C-Methyl-d-erythritol-4-phosphate (MEP) pathway of isoprenoid biosynthesis. This enzyme catalyzes the 4-diphosphocytidyl-2-C-methyl-d-erythritol 2-phosphate (CDPME2P) to 2-C-methyl-d-erythritol 2,4-cyclodiphosphate (MEcDP) with concomitant release of cytidine 5′-diphospate (CMP). Bacillus subtilis is a potential host cell for the production of isoprenoids, but few studies are performed on the key enzymes of MEP pathway in B. subtilis. In this work, the high-resolution crystal structures of IspF in native and complex with CMP from B. subtilis have been determined. Structural comparisons indicate that there is a looser packing of the subunits of IspF in B. subtilis, whereas the solvent accessible surface of its active pockets is smaller than that in Escherichia coli. Meanwhile, the protein–protein associations of 2-C-Methyl-d-erythritol-4-phosphatecytidyltransferase (IspD), CDPME kinase (IspE) and IspF from B. subtilis and E. coli, which catalyze three consecutive steps in the MEP pathway, are analyzed by native gel shift and size exclusion chromatography methods. The data here show that protein complex assembly is not detectable. These results will be useful for isoprenoid biosynthesis by metabolic engineering.

Removal of bacteriophages with different surface charges by diverse ceramic membrane materials in pilot spiking tests

2012 ◽  
Vol 66 (1) ◽  
pp. 151-157 ◽  
Author(s):  
B. Hambsch ◽  
M. Bösl ◽  
I. Eberhagen ◽  
U. Müller
Keyword(s):  
Pore Size ◽  
Ceramic Membrane ◽  
Ceramic Membranes ◽  
Pilot Scale ◽  
Size Exclusion ◽  
Feed Water ◽  
Surface Charges ◽  
Membrane Materials ◽  
Pore Sizes ◽  
Microfiltration Membranes

This study examines mechanisms for removal of bacteriophages (MS2 and phiX174) by ceramic membranes without application of flocculants. The ceramic membranes considered included ultra- and microfiltration membranes of different materials. Phages were spiked into the feed water in pilot scale tests in a waterworks. The membranes with pore sizes of 10 nm provided a 2.5–4.0 log removal of the phages. For pore sizes of 50 nm, the log removal dropped to 0.96–1.8. The membrane with a pore size of 200 nm did not remove phages. So, the removal of both MS2- and phiX174-phages depended on the pore size of the membranes. But apart from pore size also other factors influence the removal of phages. Removal was 0.5–0.9 log higher for MS2-phages compared with phiX174-phages. Size exclusion seems to be the major but not the only mechanism which influences the efficiency of phage removal by ceramic membranes.

scholarly journals Determining Soil-Water Characteristic Curves from Mercury Intrusion Porosimeter Test Data Using Fractal Theory

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 752 ◽  
Author(s):  
Gaoliang Tao ◽  
Yin Chen ◽  
Henglin Xiao ◽  
Qingsheng Chen ◽  
Juan Wan
Keyword(s):  
Fractal Dimension ◽  
Pore Size ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Fractal Theory ◽  
Characteristic Curve ◽  
Accurate Determination ◽  
Size Difference ◽  
Mercury Intrusion ◽  
Long Duration

Accurate determination of soil-water characteristic curve (SWCC) is of immense importance for understanding the mechanical behavior of unsaturated soils. Due to the difficulty and long duration of experimental procedures, it is of great significance to estimate the SWCC by indirect methods. To address this issue, in this article an effective fractal method is proposed for predicting the SWCC based on mercury intrusion porosimeter (MIP) data. Only two characteristic parameters, namely the fractal dimension and air-entry value, are needed in the presented approach. Detailed procedures for determining the parameters are clearly elaborated. Due to the influence of sample size difference on the equivalent connected pore size, a sample scale effect coefficient is proposed to predict air-entry values. The concept of “critical pore size” is introduced to obtain the optimal fractal dimension, which can accurately reflect the fractal behaviour of SWCC samples. By comparisons between predicted and experimental SWCCs, the validation of the proposed method is verified. The comparisons reveal the good agreement between the proposed approach and laboratory experiments.

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