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  • 1
    Language: English
    In: Environmental Pollution, Sept, 2013, Vol.180, p.152(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2013.05.031 Byline: Daniela Kasel, Scott A. Bradford, JiAi A imA[macron]nek, Thomas Putz, Harry Vereecken, Erwin Klumpp Abstract: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85-96%) to investigate the transport and retention of functionalized.sup.14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils. Author Affiliation: (a) Agrosphere Institute (IBG-3), Forschungszentrum Julich GmbH, 52425 Julich, Germany (b) US Salinity Laboratory, Agricultural Research Service, United States Department of Agriculture, Riverside, CA 92507, USA (c) Department of Environmental Sciences, University of California Riverside, Riverside, CA 92521, USA Article History: Received 8 February 2013; Revised 8 May 2013; Accepted 16 May 2013
    Keywords: Groundwater -- Analysis ; Soils -- Analysis ; Recharge Zones -- Analysis ; Vadose Zone -- Analysis ; Nanotubes -- Analysis ; Soil Carbon -- Analysis
    ISSN: 0269-7491
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Environmental Pollution, July 2018, Vol.238, pp.1027-1034
    Description: Undisturbed outdoor lysimeters containing arable loamy sand soil were used to examine the influence of either heavy rain events (high frequency of high rain intensity), steady rain (continuous rainfall of low rain intensity), and natural rainfall on the transport and retention of surfactant-stabilized silver nanoparticles (AgNP). In addition, the AgNP soil associations within the A horizon were analyzed by means of particle-size fractionation, asymmetrical flow field-flow fractionation coupled with UV/Vis-detection and inductively coupled plasma mass spectrometer (AF4-UV/Vis-ICP-MS), and transmission electron microscopy coupled to an energy-dispersive X-ray (TEM-EDX) analyzer. The results showed that AgNP breakthrough for all rain events was less than 0.1% of the total AgNP mass applied, highlighting that nearly all AgNP were retained in the soil. Heavy rain treatment and natural rainfall revealed enhanced AgNP transport within the A horizon, which was attributed to the high pore water flow velocities and to the mobilization of AgNP–soil colloid associations. Particle-size fractionation of the soil revealed that AgNP were present in each size fraction and therefore indicated strong associations between AgNP and soil. In particular, water-dispersible colloids (WDC) in the size range of 0.45–0.1 μm were found to exhibit high potential for AgNP attachment. The AF4-UV/Vis-ICP-MS and TEM-EDX analyses of the WDC fraction confirmed that AgNP were persistent in soil and associated to soil colloids (mainly composed of Al, Fe, Si, and organic matter). These results confirm the particularly important role of soil colloids in the retention and remobilization of AgNP in soil. Furthermore, AF4-UV/Vis-ICP-MS results indicated the presence of single, homo-aggregated, and small AgNP probably due to dissolution.
    Keywords: Silver Nanoparticles ; Transport ; Retention ; Rain Events ; Soil Colloids ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 3
    Language: English
    In: Environmental Pollution, September 2013, Vol.180, pp.152-158
    Description: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils. In undisturbed columns and a lysimeter study, complete retention of functionalized multi-walled carbon nanotubes was found in two soils at environmentally relevant conditions.
    Keywords: Undisturbed Soil ; Carbon Nanotube ; Lysimeter ; Retention Profile ; Transport Modeling ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 4
    Language: English
    In: Environmental pollution, 2013, Vol.180, pp.152-158
    Description: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized ¹⁴C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils. ; p. 152-158.
    Keywords: Carbon Nanotubes ; Vadose Zone ; Soil Profiles ; Mathematical Models ; Lysimeters ; Groundwater Contamination
    ISSN: 0269-7491
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 5
    Language: English
    In: Environmental Pollution, February 2017, Vol.221, pp.470-479
    Description: Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two C-labeled contaminants, the hydrophobic chlordecone (CLD) and the sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). The transport behaviors of CLD, SDZ, and MWCNTs were studied at environmentally relevant concentrations (0.1–10 mg L ) and they were applied in the column studies at different times. The breakthrough curves and retention profiles were simulated using a numerical model that accounted for the advective-dispersive transport of all compounds, attachment/detachment of MWCNTs, equilibrium and kinetic sorption of contaminants, and co-transport of contaminants with MWCNTs. The experimental results indicated that the presence of mobile MWCNTs facilitated remobilization of previously deposited CLD and its co-transport into deeper soil layers, while retained MWCNTs enhanced SDZ deposition in the topsoil layers due to the increased adsorption capacity of the soil. The modeling results then demonstrated that the mobility of engineered nanoparticles (ENPs) in the environment and the high affinity and entrapment of contaminants to ENPs were the main reasons for ENP-facilitated contaminant transport. On the other hand, immobile MWCNTs had a less significant impact on the contaminant transport, even though they were still able to enhance the adsorption capacity of the soil. Experimental and simulated studies demonstrated that both mobile and retained MWCNTs had a significant impact on contaminant (chlordecone and sulfadiazine) transport in soil.
    Keywords: Colloid-Facilitated Contaminant Transport ; Multi-Walled Carbon Nanotubes ; Soil ; Retention Profile ; Numerical Modeling ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 6
    Language: English
    In: Environmental Pollution, 2007, Vol.147(1), pp.4-13
    Description: The amount of non-extractable residues and the distribution of benazolin and its metabolites were evaluated three months after herbicide application ( C-labelled) in physically extracted soil fractions of topsoil layers of undisturbed soil columns with and without incorporated maize straw ( C-labelled). In addition, a variety of wet-chemical and spectroscopic methods were used to characterise the structure of organic carbon within the different soil fractions. The addition of crop residues increased the amount of dissolved organic carbon, enhanced the aromaticity of the organic carbon structure and enforced the aggregation of organomineral complexes. After incorporation of crop residues, an increase in the formation of metabolic compounds of benazolin and of non-extractable residues was detected. These results indicate that the addition of crop residues leads to a decrease in mobility and bioaccessibility of benazolin and its metabolites. Addition of crop residues increases the amount of non-extractable residues and decreases the mobility of benazolin and its metabolites.
    Keywords: Benazolin ; Herbicide ; Maize Residues ; Organic Carbon ; Soil Fractionation ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 7
    Language: English
    In: Environmental Pollution, April 2019, Vol.247, pp.907-916
    Description: Multi-walled carbon nanotubes (MWCNTs) are increasing used in commercial applications and may be released into the environment with anionic surfactants, such as sodium dodecylbenzenesulfonate (SDBS), in sewer discharge. Little research has examined the transport, retention, and remobilization of MWCNTs in the presence or absence of SDBS in porous media with controlled chemical heterogeneity, and batch and column scale studies were therefore undertaken to address this gap in knowledge. The adsorption isotherms of SDBS on quartz sand (QS), goethite coated quartz sand (GQS), and MWCNTs were determined. Adsorption of SDBS (MWCNTs » GQS 〉 QS) decreased zeta potentials for these materials, and produced a charge reversal for goethite. Transport of MWCNTs (5 mg L ) dramatically decreased with an increase in the fraction of GQS from 0 to 0.1 in the absence of SDBS. Conversely, co-injection of SDBS (10 and 50 mg L ) and MWCNTs radically increased the transport of MWCNTs when the GQS fraction was 0, 0.1, and 0.3, especially at a higher SDBS concentration, and altered the shape of retention profile. Mathematical modeling revealed that competitive blocking was not the dominant mechanism for the SDBS enhancement of MWCNT transport. Rather, SDBS sorption increased MWCNT transport by increasing electrostatic and/or steric interactions, or creating reversible interactions on rough surfaces. Sequential injection of pulses of MWCNTs and SDBS in sand (0.1 GQS fraction) indicated that SDBS could mobilize some of retained MWCNTs from the top to deeper sand layers, but only a small amount of released MWCNTs were recovered in the effluent. SDBS therefore had a much smaller influence on MWCNT transport in sequential injection than in co-injection, presumably because of a greater energy barrier to MWCNT release than retention. This research sheds novel insight on the roles of competitive blocking, chemical heterogeneity and nanoscale roughness, and injection sequence on MWCNT retention and release. Experimental and modeling studies demonstrated that SDBS had a much smaller influence on MWCNT transport in sequential injection than in co-injection experiments.
    Keywords: Multi-Walled Carbon Nanotubes ; Sodium Dodecylbenzenesulfonate ; Competitive Blocking ; Breakthrough Curves ; Retention Profiles ; Modeling ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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