Soil water retention determines plant water availability and contaminant transport processes in the subsurface environment. However, it is usually difficult to measure soil water retention characteristics. In this study, an analytical... more
Soil water retention determines plant water availability and contaminant transport processes in the subsurface environment. However, it is usually difficult to measure soil water retention characteristics. In this study, an analytical model based on a fractional bulk density (FBD) concept was presented for estimating soil water retention curves. The concept allows partitioning of soil pore space according to the relative contribution of certain size fractions of particles to the change in total pore space. The input parameters of the model are particle size distribution (PSD), bulk density, and residual water content at water pressure head of 15,000 cm. The model was tested on 30 sets of water retention data obtained from various types of soils that cover wide ranges of soil texture from clay to sand and soil bulk density from 0.33 g/cm3 to 1.65 g/cm3. Results showed that the FBD model was effective for all soil textures and bulk densities. The estimation was more sensitive to the c...
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Chemotaxis and haptotaxis are important biological mechanisms that influence microbial movement toward concentrated chemoattractants in mobile liquids and along immobile surfaces, respectively. This study investigated their coupled... more
Chemotaxis and haptotaxis are important biological mechanisms that influence microbial movement toward concentrated chemoattractants in mobile liquids and along immobile surfaces, respectively. This study investigated their coupled effect, as induced by naphthalene (10 mg L−1), on the transport and retention of two pollutant-degrading bacteria, Pseudomonas fluorescens 5RL (Pf5RL) and Pseudomonas stutzeri DQ1 (PsDQ1), in quartz sand and natural soil. The results demonstrated that PsDQ1 was not chemotactic, whereas Pf5RL was chemotactic at 25°C but not at 4°C due to the restricted movement. In a quartz sand column, haptotaxis did not play a role in increasing the transport of Pf5RL as compared with chemotaxis. Compared with a naphthalene-free soil column, Pf5RL broke through naphthalene-presaturated soil columns to reach a stable effluent concentration 0.5 pore volumes earlier due to advective chemotaxis occurring behind the plume front in the bulk solution. Pf5RL also demonstrated greater retention (e.g., a doubled rate of attachment and a one-third smaller breakthrough percentage) due to along-surface haptotaxis and near-surface chemotaxis occurring in less mobile water near the soil surface. However, both chemotaxis and haptotaxis were weakened when Pf5RL co-transported with naphthalene due to reduced adsorption of naphthalene on the soil. This study suggests that surface adsorption of naphthalene can mediate the relative importance of advective chemotaxis (facilitating initial breakthrough), near-surface chemotaxis (increasing bacterial collision), and haptotaxis (increasing bacterial residence time).
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Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were... more
Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were conducted to investigate the coupled effects of ionic strength, iron oxides (hematite), and soil colloids on the transport of CNCs through quartz sand and natural soils (red earth and brown earth). Results showed that CNCs had high mobility in oxide-free sand and that iron oxide coating reduced the mobility of CNCs. An analysis of Derjaguin-Landau-Verwey-Overbeek interactions indicated that CNCs exhibited a deep primary minimum, nonexistent maximum repulsion and secondary minimum on hematite-coated sand, favorable for the attachment of CNCs. The maximum effluent percentage of CNCs was 96% in natural soils at 5 mM, but this value decreased to 4% at 50 mM. Soil colloids facilitated the transport of CNCs in brown earth with larger effect at higher ionic streng...
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Triclosan is an antimicrobial agent, which is widely used in personal care products including toothpaste, soaps, deodorants, plastics, and cosmetics. Widespread use of triclosan has resulted in its release into wastewater, surface water,... more
Triclosan is an antimicrobial agent, which is widely used in personal care products including toothpaste, soaps, deodorants, plastics, and cosmetics. Widespread use of triclosan has resulted in its release into wastewater, surface water, and soils and has received considerable attention in the recent years. It has been reported that triclosan is detected in various environmental compartments. Toxicity studies have suggested its potential environmental impacts, especially to aquatic ecosystems. To date, removal of triclosan has attracted rising attention and biodegradation of triclosan in different systems, such as axenic cultures of microorganisms, full-scale WWTPs, activated sludge, sludge treatment systems, sludge-amended soils, and sediments has been described. In this study, an extensive literature survey was undertaken, to present the current knowledge of the biodegradation behavior of triclosan and highlights the removal and transformation processes to help understand and pred...
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The application of sewage and manure in protected vegetable cultivation can induce the occurrence of heavy metals contamination. The present research studied the transformation of heavy metals (Cd, Cu, Pb and Zn) by incubating... more
The application of sewage and manure in protected vegetable cultivation can induce the occurrence of heavy metals contamination. The present research studied the transformation of heavy metals (Cd, Cu, Pb and Zn) by incubating contaminated protected soil with maize straw and then leaching. The results showed that soil pH was significantly decreased, being more evident in maize straw treatment; soil Eh dropped quickly below -280 mV. Maize straw treatment promoted the activation of Cd, Cu, Pb and Zn from soil, and the total percent of oxidizable fraction and residual fraction of Cd, Cu, Pb and Zn declined at 9 day; the amount of Cd, Cu, Pb and Zn in soil reduced 18.1%, 19.0%, 16.1% and 15.7% at 15 day, respectively. Compared to control, maize straw treatment could increase the concentrations of dissolved Cd and Zn, but Cu decreased. The concentration of colloidal-bound Cd and Pb increased, Cu decreased and no significant change occurred in Zn in maize straw treatment. Strong reductive...
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Pharmaceutical and personal care products (PPCPs) enter soils through reclaimed water irrigation and biosolid land applications. Colloids, such as clays, that are present in soil may interact with PPCPs and thus affect their fate and... more
Pharmaceutical and personal care products (PPCPs) enter soils through reclaimed water irrigation and biosolid land applications. Colloids, such as clays, that are present in soil may interact with PPCPs and thus affect their fate and transport in the subsurface environment. This study addresses the influence of soil colloids on the sorption and transport behaviors of PPCPs through laboratory column experiments. Results show that the affinities of PPCPs for colloids vary with their molecular chemistry and solution ionic strength. The presence of colloids promotes the breakthrough of ciprofloxacin (over 90% sorbed on colloids) from ~4% to 30-40%, and the colloid-facilitated effect was larger at lower ionic strength (e.g., 2 mM). In comparison, the net effect of colloids on the transport of tetracycline (~50% sorbed on colloids) could be facilitation or inhibition, depending on solution chemistry. This dual effect of colloids is primarily due to the opposite response of migration of di...
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Organic pollutants in soils might threaten the environmental and human health. Manufactured nanoparticles are capable to reduce this risk efficiently due to their relatively large capacity of sorption and degradation of organic... more
Organic pollutants in soils might threaten the environmental and human health. Manufactured nanoparticles are capable to reduce this risk efficiently due to their relatively large capacity of sorption and degradation of organic pollutants. Stability, mobility, and reactivity of nanoparticles are prerequisites for their efficacy in soil remediation. On the basis of a brief introduction of these issues, this review provides a comprehensive summary of the application and effectiveness of various types of manufactured nanoparticles for removing organic pollutants from soil. The main categories of nanoparticles include iron (oxides), titanium dioxide, carbonaceous, palladium, and amphiphilic polymeric nanoparticles. Their advantages (e.g., unique properties and high sorption capacity) and disadvantages (e.g., high cost and low recovery) for soil remediation are discussed with respect to the characteristics of organic pollutants. The factors that influence the decontamination effects, suc...
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The U.S.-China EcoPartnership for Environmental Sustainability (USCEES), one of 30 EcoPartnerships, was established within the U.S.-China Strategic Economic Dialogue framework in May 2011 by a joint agreement between the U.S. Department... more
The U.S.-China EcoPartnership for Environmental Sustainability (USCEES), one of 30 EcoPartnerships, was established within the U.S.-China Strategic Economic Dialogue framework in May 2011 by a joint agreement between the U.S. Department of State and China's National Development and Reform Commission. The USCEES has the goal of fostering bi-national research innovation, communication, and entrepreneurship to address the interconnected challenges of environmental, social, and economic sustainability. Research and education programs within the USCEES are focused on understanding current and past degradation of natural resources, investigating the drivers, impacts, and mitigation of global climate change, and assessing options for sustainable use of natural resources. Although both the U.S. and China have embraced a future based on science, technology, and innovation, our bi-national framework acknowledges that these two nations have vastly different cultural, political, and demographic legacies that could pose distinct challenges to uniform solutions or mandated collaborative networks. The peer-to-peer connections that drive the research component of the USCEES program are promoted and initiated from the ground up; they are based on the voluntary participation of scientists and engineers who are fascinated by the intellectual challenge of solving complex problems of inherent interest to them. Herein, we present highlights of USCEES activities that describe our efforts to discover, incubate, and nurture U.S.-China research collaborations to meet our collective goals. We discuss our pilot programs that are designed to highlight university facilities, resources, and technologies for tech transfer and licensing with an environmental solutions-oriented direction. Additionally, programs to promote cross-EcoPartnership collaborations are discussed. (C) 2015 AIP Publishing LLC.
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The aim of this study was to demonstrate the variations in bioavailability remaining in industrial and agricultural soils contaminated by polycyclic aromatic hydrocarbons (PAHs) after bioremediation. After inoculation of Mycobacterium sp.... more
The aim of this study was to demonstrate the variations in bioavailability remaining in industrial and agricultural soils contaminated by polycyclic aromatic hydrocarbons (PAHs) after bioremediation. After inoculation of Mycobacterium sp. and Mucor sp., PAH biodegradation was tested on a manufactured gas plant (MGP) soil and an agricultural soil. PAH bioavailability was assessed before and after biodegradation using solid-phase extraction (Tenax-TA extraction) and solid-phase micro-extraction (SPME) to represent bioaccessibility and chemical activity of PAHs, respectively. Only 3- and 4-ring PAHs were noticeably biodegradable in the MGP soil. PAH biodegradation in the agricultural soil was different from that in the MGP soil. The rapidly desorbing fractions (Frap) extracted by Tenax-TA and the freely dissolved concentrations of 3- and 4-ring PAHs determined by SPME from the MGP soil decreased after 30 days biodegradation; those values of the 5- and 6-ring PAHs changed to a lesser de...
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The aim of this study was to evaluate the biological toxicity of cellulose nanocrystals (CNCs) using the constitutively bioluminescent luxCDABE-based bioreporter Escherichia coli 652T7. The effects of CNCs on E. c oli 652T7 biotoxicity... more
The aim of this study was to evaluate the biological toxicity of cellulose nanocrystals (CNCs) using the constitutively bioluminescent luxCDABE-based bioreporter Escherichia coli 652T7. The effects of CNCs on E. c oli 652T7 biotoxicity were investigated at different CNC concentrations, reaction times, and IC50 values. CNC toxicity was also compared with and without ultrasonic dispersion to establish dispersibility effects. The results demonstrated that CNCs were not significantly toxic at concentrations at or below 250 mg/L. At concentrations higher than 300 mg/L, toxicity increased linearly as CNC concentrations increased up to 2000 mg/L. IC50 calculations demonstrated an increase in cytotoxicity as CNC exposure times increased, and elevated dispersibility of the CNCs were shown to increase cytotoxicity effects. These results suggest that CNCs can impact microbial populations if elevated concentration thresholds are met.
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In this study, the characteristics of cadmium (Cd) uptake by roots and translocation from roots to leaves of two eggplant species (Solanum melongena and Solanum torvum) under relatively low Cd concentrations were investigated using stable... more
In this study, the characteristics of cadmium (Cd) uptake by roots and translocation from roots to leaves of two eggplant species (Solanum melongena and Solanum torvum) under relatively low Cd concentrations were investigated using stable (108)Cd isotope through a number of hydroponic experiments. The uptake and translocation of (108)Cd was compared with those of (70)Zn and (15)N. The results showed more (108)Cd was loaded to the vascular channels and translocated upward to the leaves in S. melongena than in S. torvum, while the (108)Cd concentrations were significantly lower in the roots of S. melongena than in S. torvum. When the phloem and xylem were wounded by grafting treatments, the foliar (108)Cd concentrations were decreased by more than 66 % regardless of the rootstock species, whereas the uptake of (108)Cd in the root was not inhibited by grafting. Similar grafting effects were observed for (70)Zn. Hence, wounding phloem and xylem by grafting disturbed the upward transport...
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The possible health risks from heavy metal (Zn, Cu, Cr, Ni, Pb, and Cd) contamination to the local population through the food chain were evaluated in Tianjin, China, a city with a long history of sewage irrigation. Results showed that... more
The possible health risks from heavy metal (Zn, Cu, Cr, Ni, Pb, and Cd) contamination to the local population through the food chain were evaluated in Tianjin, China, a city with a long history of sewage irrigation. Results showed that the continuous application of wastewater has led to an accumulation of heavy metals in the soil, and 54.5 and 18.25 % soil samples accumulated Cd and Zn in concentrations exceeding the permissible limits in China. Concentrations of heavy metals in wheat grain decreased in the order of…
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Pharmaceuticals (PCs) have been widely detected in natural environment due to agricultural application of reclaimed water, sludge and animal wastes. Their potential risks to various ecosystems and even to human health have caused great... more
Pharmaceuticals (PCs) have been widely detected in natural environment due to agricultural application of reclaimed water, sludge and animal wastes. Their potential risks to various ecosystems and even to human health have caused great concern; however, little was known about their environmental behaviors. Colloids (such as clays, metal oxides, and particulate organics) are kind of substances that are active and widespread in the environment. When PCs meet colloids, their interaction may influence the fate, transport, and toxicity of PCs. This review summarizes the progress of studies on the role of colloids in mediating the environmental behaviors of PCs. Synthesized results showed that colloids can adsorb PCs mainly through ion exchange, complexation and non-electrostatic interactions. During this process the structure of colloids and the stability of PCs may be changed. The adsorbed PCs may have higher risks to induce antibiotic resistance; besides, their transport may also be al...
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Subtropical rivers support a highly diverse array of benthic macroinvertebrates. In this study, by combining historical data and new data, we identified specific changes in the Guanlan River, in South China, from 1981 to 2011, and... more
Subtropical rivers support a highly diverse array of benthic macroinvertebrates. In this study, by combining historical data and new data, we identified specific changes in the Guanlan River, in South China, from 1981 to 2011, and evaluated the effectiveness of an ecological restoration project under highly polluted conditions. From 1981 to 2011, the water quality in the Guanlan River underwent three major stages. With the deterioration of water quality, there was an overall decrease in the species number of macroinvertebrates in the Guanlan River, an increase in macroinvertebrate density, and a reduction of the biodiversity, and a reduction of functional feeding groups. In 2011, after five years of comprehensive remediation, the Guanlan River was somewhat improved. Macroinvertebrate biodiversity in the middle reach of the Guanlan River, where a key ecological restoration engineering project was implemented, did not differ significantly from other sites. This finding indicates that ...
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Understanding water uptake and transport through the soil-plant continuum is vital for ecosystem management and agricultural water use. Plant water uptake under natural conditions is a non-steady transient flow controlled by root... more
Understanding water uptake and transport through the soil-plant continuum is vital for ecosystem management and agricultural water use. Plant water uptake under natural conditions is a non-steady transient flow controlled by root distribution, plant configuration, soil hydraulics, and climatic conditions. Despite significant progress in model development, a mechanistic description of transient water uptake has not been developed or remains incomplete. Here, based on advanced electrical network theory (RLC circuit theory), we developed a non-steady state biophysical model to mechanistically analyze the fluctuations of uptake rates in response to water stress. We found that the non-steady-state model captures the nature of instantaneity and hysteresis of plant water uptake due to the considerations of water storage in plant xylem and coarse roots (capacitance effect), hydraulic architecture of leaf system (inductance effect), and soil-root contact (fuse effect). The model provides ins...
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Ocean acidification and pollution coexist to exert combined effects on the functions and services of marine ecosystems. Ocean acidification can increase the biotoxicity of heavy metals by altering their speciation and bioavailability.... more
Ocean acidification and pollution coexist to exert combined effects on the functions and services of marine ecosystems. Ocean acidification can increase the biotoxicity of heavy metals by altering their speciation and bioavailability. Marine pollutants, such as heavy metals and oils, could decrease the photosynthesis rate and increase the respiration rate of marine organisms as a result of biotoxicity and eutrophication, facilitating ocean acidification to varying degrees. Here we review the complex interactions between ocean acidification and pollution in the context of linkage of multiple stressors to marine ecosystems. The synthesized information shows that pollution-affected respiration acidifies coastal oceans more than the uptake of anthropogenic carbon dioxide. Coastal regions are more vulnerable to the negative impact of ocean acidification due to large influxes of pollutants from terrestrial ecosystems. Ocean acidification and pollution facilitate each other, and thus coastal environmental protection from pollution has a large potential for mitigating acidification risk.
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... Available substances such as glucose can shift soil microorganisms from dormancy to activity, increasing nutrient demand and leading to the significant utilization of extraneous N (eg, NH 4 + ) ([Blagodatskaya et al., 2007], [Brant et... more
... Available substances such as glucose can shift soil microorganisms from dormancy to activity, increasing nutrient demand and leading to the significant utilization of extraneous N (eg, NH 4 + ) ([Blagodatskaya et al., 2007], [Brant et al., 2006], [De Nobili et al., 2001] and [Mondini ...
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Environmental Engineering, Civil Engineering, Geology, Chemistry, Water, and 15 moreApplied Economics, Soil moisture, Resources, van der Waals interaction, Colloids, Groundwater Quality, Mobilization, Steady state, Water Content, Flow Rate, Ionic Strength, Experimental Data, Cumulant, Advection Dispersion Equation, and Infiltration rate
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Soil water retention characteristic is an important property of soil. Indirect estimation of this property using easily measurable soil properties remains the research focus of many soil scientists. In this study, a general approach was... more
Soil water retention characteristic is an important property of soil. Indirect estimation of this property using easily measurable soil properties remains the research focus of many soil scientists. In this study, a general approach was proposed to derive soil water retention characteristic ...
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ABSTRACT Fractal geometry concepts have been widely applied as a tool for describing complex natural phenomena, for instance, mechanics and physics of rocks and soils. However, they are seldom used to describe deposited soils. The... more
ABSTRACT Fractal geometry concepts have been widely applied as a tool for describing complex natural phenomena, for instance, mechanics and physics of rocks and soils. However, they are seldom used to describe deposited soils. The objectives of this study were to classify soils collected from dam farmlands according to their particle size distributions (PSD) and to examine the relationship between scaling exponents and soil textures (clay and/or sand content). A total of 649 PSD of deposited soils were collected and determined using laser granulometry. The soils were grouped into four texture classes: silt loam, sandy loam, loamy sand, and sand. All the PSD fit the Pore-Solid fractal model well. The mean values of composite scaling constant (c) and fractal dimension (D) differed among soil texture classes. The significant relationships between the values of D and the contents of sand, silt, and clay fractions were found to follow a sigmoid trend. Our results show that the fractal dimension of PSD indicates the degree of soil detachment or soil desertification and the effect of check dams on soil conservation.
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ABSTRACT
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Organic materials are widespread in natural soil and aquatic environments. Their effect on virus transport is very important in assessing the risk for contamination of ground water by viruses. This study aimed to determine how different... more
Organic materials are widespread in natural soil and aquatic environments. Their effect on virus transport is very important in assessing the risk for contamination of ground water by viruses. This study aimed to determine how different forms (mineral-associated and dissolved) of natural organic matter influence the retention and transport of two bacteriophages (MS-2 and phiX174) in two porous media (a sand and a soil). We found that mineral-associated organic matter significantly promoted the transport of one virus (MS-2) but not the other (phiX174) in a phosphate-buffered saline solution. Similarly, MS-2 was retained less in sand columns with increasing concentrations of dissolved humic acid, while little effect was observed for phiX174 under the same conditions. The two viruses have different surface properties and thus exhibited different reactivity to the metal oxides present on sand particles and were affected differently by organic matter. Because the organic matter used in the study was negatively charged and hydrophilic, blocking of virus sorption sites and increasing of virus-medium electrostatic repulsion arising from modification of the sand and virus surface by organic matter are probably responsible for the facilitated transport. For dissolved humic acid, its competition for sorption sites with viruses was an additional mechanism involved. This study suggests that the effect of organic matter varied depending on the organic material properties and the type of viruses involved. As a general trend, the effect of organic matter was dominated by electrostatic rather than hydrophobic interactions.
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Microbiology, Earth Sciences, Filtration, Risk assessment, Adsorption, and 15 moreBiological Sciences, Mobility, Environmental Sciences, Porous Media, Ground Water, Humic acid, ARENA, Environmental quality, Dissolved Organic Carbon, Risk Assessment, Organic Matter, Environment Quality, Natural Organic Matter, Organic Chemicals, and Phosphate Buffer Saline
Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand... more
Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand column experiments were performed to examine the effects of a positively charged Al-oxide, which was coated on sand particles, on the retention and transport of viruses (phiX174 and MS-2) in background solutions of different ionic strength and composition. We found that the Al-oxide coating on sand significantly removed viruses during their transport in a phosphate buffered saline (PBS) solution. Mass balance calculations showed that 34% of the input MS-2 was inactivated/irreversibly sorbed on the surface of Al-oxide coated sand whereas 100% of phiX174 was recovered. Results from this study also indicated that higher ionic strength facilitated the transport of both phiX174 and MS-2 through the Al-oxide coated sand. This was attributed to the effect of ion shielding, which at higher ionic strength decreased the electrostatic attraction between the viral particles and the sand surface and consequently decreased virus sorption. Strong effect of the ionic strength indicates that an outer-sphere complexation mechanism was responsible for the virus sorption on the Al-oxide coated sand. Ion composition of the background solutions was also found to be a significant factor in influencing virus retention and transport. Virus transport was enhanced in the presence of phosphate (HPO(4)(2-)) as compared to bicarbonate (HCO(3)(-)), and the effect of HPO(4)(2-) was more significant on MS-2 than on phiX174. The presence of bivalent cations (Ca(2+) and Mg(2+)) increased virus transport because the cations partially screened the negative charges on the viruses therefore decreased the electrostatic attraction between the positively charged sand surface and the negatively charged viruses. Mass recovery data indicated that bivalent cations gave rise to a certain degree of inactivation/irreversibly sorption of phiX174 on the surface of Al-oxide coated sand. On the contrary, the bivalent cations appeared to have protected MS-2 from inactivation/irreversibly sorption. This study provides some insights into the mechanisms responsible for virus retention and transport in porous media.
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Metal oxides have great potential for controlling the fate and transport of viruses in the subsurface and water-treatment systems. The processes, however, are subject to solution chemistry. In this study, a number of column experiments... more
Metal oxides have great potential for controlling the fate and transport of viruses in the subsurface and water-treatment systems. The processes, however, are subject to solution chemistry. In this study, a number of column experiments were conducted to examine the effects of solution pH and anions (carbonate and phosphate) on attachment, transport, and inactivation of two bacteriophages (phiX174 and MS-2) in goethite-coated sand medium. Removal of both viruses on goethite-coated sand increased as solution pH decreased from 9.3 to 7.5, due mostly to virus inactivation. MS-2, a relatively hydrophobic virus with a lower isoelectric point (3.9), was more sensitive to the change of solution pH than phiX174, a relatively hydrophilic virus with a higher isoelectric point (6.6), in terms of their attachment and inactivation on goethite. About 90% of the MS-2 particles removed by goethite (accounting for 81% of the total input) were inactivated at pH 7.5, whereas all of the removed MS-2 particles (accounting for 10% of the total input) still remained infectious at pH 9.3. In comparison, approximately 74% of the goethite-bound phiX174 particles (accounting for 95% of the total input) lost their infectivity at pH 7.5, in contrast to a complete recovery at pH 9.3 (accounting for 65% of the total input) when the columns were eluted using a beef extract solution (pH 9.5). Presence of phosphate (20 mM H(2)PO(4)(-)) in input solution reduced virus attachment and appeared to protect the viruses from being inactivated during transport; this effect was more significant on MS-2 than on phiX174. Specifically, approximately 29% of the phiX174 particles and approximately 49% of MS-2 particles injected into the column were removed during transport. Mass recovery data showed that no phiX174 was inactivated in the presence of phosphate, whereas about 38% of the MS-2 particles attached on goethite lost their infectivity. Conversely, presence of carbonate on goethite increased virus attachment and inactivation due to contribution of additional attachment sites from protonated surface groups of the carbonate ions that were adsorbed on goethite. About 70% of the total input viruses (both phiX174 and MS-2) were removed during transport, of which 35% phiX174 and 85% MS-2 were eventually inactivated.
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Maize, Field Crops, Potential Evapotranspiration, Soil sciences, Biomass production, and 12 moreSolar radiation, Analytical Model, Soil Physical Properties, Bulk Density, Particle Size Distribution, Soil Water, Leaf water potential, Root Length, Zea Mays L, Water uptake, Water Potential, and Accuracy analysis
The purpose of this study was to examine the mechanisms responsible for deposition and transport of amphiphilic colloids with a wide range of particle sizes (20-420 nm) through porous media. A series of saturated and unsaturated column... more
The purpose of this study was to examine the mechanisms responsible for deposition and transport of amphiphilic colloids with a wide range of particle sizes (20-420 nm) through porous media. A series of saturated and unsaturated column experiments were conducted using amphiphilic latex microspheres and a hydrophilic silica colloid. We found that the amphiphilic latex particles were retained to a greater extentthan the hydrophilic silica colloid in unsaturated media. This was attributed to colloidal attachment atthe air-water interface due mainly to hydrophobic interactions. We also found that dependence of colloid retention on particle size was nonlinear. There existed a fraction of colloids with greater mobility than other fractions, which we referred to as the most mobile colloids. As particle size increased from 20 to 420 nm, colloid deposition rate first decreased to reach a minimum value at --100 nm then increased, indicating that different retention mechanisms were involved. We showed that conducting saturated transport experiments and analysis using filtration theory may be an effective approach for determining the most mobile colloid size(s) in porous media, perhaps even for unsaturated flow conditions. This study highlights the importance of including size effect and surface properties when predicting concentrations and fluxes of amphiphilic colloids or colloid-bound amphiphilic and hydrophobic contaminants in the subsurface environment.
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Chemistry, Electrochemistry, Minerals, Clay Minerals, Medicine, and 15 moreMultidisciplinary, Adsorption, Heavy Metal, Lead, Fluorides, Cadmium, Specific surface area, Natural Environment, Surface Charge, Aluminum oxide, Electrochemical Properties, Organic Matter, Ferric Compounds, Soil Pollutants, and Hydroxyl Radical
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ABSTRACT Different hydraulic parameters, including the hydraulic shear stress, unit length shear force, steam power, unit steam power, and effective stream power were used to quantify flow detachment. Most former studies were conducted... more
ABSTRACT Different hydraulic parameters, including the hydraulic shear stress, unit length shear force, steam power, unit steam power, and effective stream power were used to quantify flow detachment. Most former studies were conducted for flow detachment under uniform slope surface conditions, while a few studies compared different slope surface conditions. The uniform bare loess was prepared in laboratory experiments. Natural fallowed soil loess with stone covers was prepared in field experiments. The objective of this study was to assess the differences in hydraulic parameters and sediment detachment under these different soil surface conditions. Our results show that the unit sediment load (Rs) has a good linear relationship with the unit runoff rate (Rr) for the flume and field experiments, and the relationship can be expressed as the function: Rs = 0.262Rr − 0.802 (R2 = 0.947). The rate of Manning roughness coefficient to mean flow depth (n/h) is a good hydraulic indicator like as the stream power and Reynolds number for predicting the sediment load. Hydraulic parameters n/h, Re, and ω are good indicators for the unit area sediment load for both the flume and field experiments, while Fr, f, and τ are good indicators for the unit area sediment load only when the flume experiments and field experiments are individually analyzed. Among the three good indicators (ω, Re, and n/h), n/h is better than the other two for predicting sediment load in rill erosion for both flume and field experiments, as well as for the unit solute transport rate (MBr). The parameter of n/h probably is not only a good hydraulic parameter as an indicator for both sediment and solute transport, but also a good hydraulic parameter which link with runoff energies. The parameter n/h represents the flow wave of runoff and is an important factor to represent the energy for water and sediment transport, and the flow wave celerity (vw) is related to n/h by: vw = 1.585(n/h)− 0.527 (R2 = 0.978).
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Understanding colloid transport at the Hanford site in Washington State is critical in assessing migration of radionuclides because colloid transport is a potential means for facilitated off-site migration of radioactive wastes. In this... more
Understanding colloid transport at the Hanford site in Washington State is critical in assessing migration of radionuclides because colloid transport is a potential means for facilitated off-site migration of radioactive wastes. In this study, eight saturated column experiments were ...
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Colloid transport may facilitate off-site transport of radioactive wastes at the Hanford site, Washington State. In this study, column experiments were conducted to examine the effect of irrigation schedule on releases of in situ colloids... more
Colloid transport may facilitate off-site transport of radioactive wastes at the Hanford site, Washington State. In this study, column experiments were conducted to examine the effect of irrigation schedule on releases of in situ colloids from two Hanford sediments during saturated and ...
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Gui-Rui Yu1,4, Tatsuaki Kobayashi2, Jie Zhuang1, Qiu-Feng Wang1 & Le-Qing Qu3 1Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 3 Datun Road, Chaoyang District, PO Box 9717, Beijing 100101, PR... more
Gui-Rui Yu1,4, Tatsuaki Kobayashi2, Jie Zhuang1, Qiu-Feng Wang1 & Le-Qing Qu3 1Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 3 Datun Road, Chaoyang District, PO Box 9717, Beijing 100101, PR China 2Faculty of ...