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  • 1
    Language: English
    In: Environmental Pollution, April, 2013, Vol.175, p.110(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2012.12.027 Byline: Guohui Wang, Peter Grathwohl Abstract: Isosteric heats ([DELTA]H) of sorption/desorption of phenanthrene were determined for carbonaceous materials (Pahokee peat, lignite, and high-volatile bituminous coal) and two soils based on reported equilibrium sorption/desorption isotherms at four different temperatures (4, 20, 46 and 77 [degrees]C). In addition, [DELTA]H for desorption of native phenanthrene was determined to elucidate the "aging" effect by equilibrating samples with water at six temperatures (20, 40, 53, 61, 73, and 86 [degrees]C). Isosteric heats decreased with increasing solute concentration and were in a range of 19-35 kJ mol.sup.-1. Values higher than the heat of octanol-water phase transfer for phenanthrene (19 kJ mol.sup.-1) imply that both partitioning and adsorption processes are involved for these materials, where the sorptive contributions from both processes were estimated based on the phenanthrene thermodynamic data. Moreover, on the basis of [DELTA]H values of desorption, release of native and spiked phenanthrene from our samples was similar. Author Affiliation: Center for Applied Geoscience, University Tubingen, Holderlinstr. 12, D-72074 Tubingen, Germany Article History: Received 26 June 2012; Revised 20 December 2012; Accepted 21 December 2012
    Keywords: Bituminous Coal ; Soils ; Adsorption ; Lignite ; Peat
    ISSN: 0269-7491
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Environmental pollution, 2013, Vol.175, pp.110-116
    Description: Isosteric heats (ΔH) of sorption/desorption of phenanthrene were determined for carbonaceous materials (Pahokee peat, lignite, and high-volatile bituminous coal) and two soils based on reported equilibrium sorption/desorption isotherms at four different temperatures (4, 20, 46 and 77 °C). In addition, ΔH for desorption of native phenanthrene was determined to elucidate the “aging” effect by equilibrating samples with water at six temperatures (20, 40, 53, 61, 73, and 86 °C). Isosteric heats decreased with increasing solute concentration and were in a range of 19–35 kJ mol⁻¹. Values higher than the heat of octanol–water phase transfer for phenanthrene (19 kJ mol⁻¹) imply that both partitioning and adsorption processes are involved for these materials, where the sorptive contributions from both processes were estimated based on the phenanthrene thermodynamic data. Moreover, on the basis of ΔH values of desorption, release of native and spiked phenanthrene from our samples was similar. ; p. 110-116.
    Keywords: Peat ; Phenanthrene ; Desorption ; Solutes ; Lignite ; Adsorption ; Heat ; Temperature ; Soil
    ISSN: 0269-7491
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 3
    Language: English
    In: Environmental Pollution, April 2013, Vol.175, pp.110-116
    Description: Isosteric heats (Δ ) of sorption/desorption of phenanthrene were determined for carbonaceous materials (Pahokee peat, lignite, and high-volatile bituminous coal) and two soils based on reported equilibrium sorption/desorption isotherms at four different temperatures (4, 20, 46 and 77 °C). In addition, Δ for desorption of native phenanthrene was determined to elucidate the “aging” effect by equilibrating samples with water at six temperatures (20, 40, 53, 61, 73, and 86 °C). Isosteric heats decreased with increasing solute concentration and were in a range of 19–35 kJ mol . Values higher than the heat of octanol–water phase transfer for phenanthrene (19 kJ mol ) imply that both partitioning and adsorption processes are involved for these materials, where the sorptive contributions from both processes were estimated based on the phenanthrene thermodynamic data. Moreover, on the basis of Δ values of desorption, release of native and spiked phenanthrene from our samples was similar. ► Total isosteric heats were separated into adsorption and partitioning components. ► No significant sorption/desorption hysteresis occurred based on isosteric heats. ► Desorption isosteric heat of native phenanthrene was similar to a spiked lab sample. Temperature-dependent sorption isotherms of phenanthrene on carbonaceous materials are used to determine isosteric heat for analyzing the relative effect of adsorption and partitioning.
    Keywords: Isosteric Heat ; Sorption/Desorption ; Phenanthrene ; Carbonaceous Material ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 4
    Language: English
    In: Water Research, 01 February 2013, Vol.47(2), pp.769-780
    Description: For several pilot-scale constructed wetlands (CWs: a planted and unplanted gravel filter) and a hydroponic plant root mat (operating at two water levels), used for treating groundwater contaminated with BTEX, the fuel additive MTBE and ammonium, the hydrodynamic behavior was evaluated by means of temporal moment analysis of outlet tracer breakthrough curves (BTCs): hydraulic indices were related to contaminant mass removal. Detailed investigation of flow within the model gravel CWs allowed estimation of local flow rates and contaminant loads within the CWs. Best hydraulics were observed for the planted gravel filter (number of continuously stirred tank reactors  = 11.3, dispersion number = 0.04, Péclet number = 23). The hydroponic plant root mat revealed lower and pronounced dispersion tendencies, whereby an elevated water table considerably impaired flow characteristics and treatment efficiencies. Highest mass removals were achieved by the plant root mat at low level: 98% (544 mg m d ), 78% (54 mg m d ) and 74% (893 mg m d ) for benzene, MTBE and ammonium–nitrogen, respectively. Within the CWs the flow behavior was depth-dependent, with the planting and the position of the outlet tube being key factors resulting in elevated flow rate and contaminant flux immediately below the densely rooted porous media zone in the planted CW, and fast bottom flow in the unplanted reference. ► Plants improve the contaminant removal efficiency in the gravel CW. ► The hydroponic plant root mat achieves better contaminant removal than the planted gravel CW. ► Plants induce flow and thus contaminant flux into the root zone of the gravel CW. ► Local residence time distributions allow to observe dead zones and preferential flow paths.
    Keywords: Tracer Test ; Fluorescein ; Hydroponic Plant Root Mat ; Local Contaminant Loads ; Benzene ; Mtbe ; Ammonium Removal ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 5
    Language: English
    In: Science of the Total Environment, 01 January 2016, Vol.540, pp.444-454
    Description: Increasing numbers of organic micropollutants are emitted into rivers via municipal wastewaters. Due to their persistence many pollutants pass wastewater treatment plants without substantial removal. Transport and fate of pollutants in receiving waters and export to downstream ecosystems is not well understood. In particular, a better knowledge of processes governing their environmental behavior is needed. Although a lot of data are available concerning the ubiquitous presence of micropollutants in rivers, accurate data on transport and removal rates are lacking. In this paper, a mass balance approach is presented, which is based on the Lagrangian sampling scheme, but extended to account for precise transport velocities and mixing along river stretches. The calculated mass balances allow accurate quantification of pollutants' reactivity along river segments. This is demonstrated for representative members of important groups of micropollutants, e.g. pharmaceuticals, musk fragrances, flame retardants, and pesticides. A model-aided analysis of the measured data series gives insight into the temporal dynamics of removal processes. The occurrence of different removal mechanisms such as photooxidation, microbial degradation, and volatilization is discussed. The results demonstrate, that removal processes are highly variable in time and space and this has to be considered for future studies. The high precision sampling scheme presented could be a powerful tool for quantifying removal processes under different boundary conditions and in river segments with contrasting properties.
    Keywords: Micropollutants ; River Segments ; Mass Balances ; Removal Processes ; Diurnal Patterns ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 6
    Language: English
    In: Geochimica et Cosmochimica Acta, Nov 1, 2013, Vol.120, p.195(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.gca.2013.06.031 Byline: Massimo Rolle, Muhammad Muniruzzaman, Christina M. Haberer, Peter Grathwohl Abstract: We study the influence of Coulombic effects on transport of charged species in saturated porous media in advection-dominated flow regimes. We focus on transverse hydrodynamic dispersion and we performed quasi two-dimensional flow-through experiments to investigate transport of dilute electrolyte solutions. The experiments were repeated for two average flow velocities (1.5 and 6m/day) representing advection-dominated and strongly advection-dominated flow conditions, respectively. Numerical transport simulations have been conducted to quantitatively interpret the experimental results. The adopted modeling approach is based on a multicomponent formulation and on the accurate description of transverse dispersion. The latter entails a non-linear dependence of the transverse dispersion coefficient on the flow velocity as well as a compound-specific dependence on the molecular diffusion of the transported solute. These dependencies hold true at low and also at high flow velocities. Our experimental and modeling results show that Coulombic cross-coupling of dispersive fluxes of charged species in porous media significantly affects the lateral displacement of charged species in flow-through systems. Such effects are remarkable not only in diffusion-dominated but also in advection-dominated flow regimes. Their accurate description requires a multicomponent modeling approach and the recognition of the key role of molecular diffusion for both the pore diffusion and the mechanical dispersion terms of hydrodynamic dispersion. Article History: Received 4 April 2013; Accepted 17 June 2013 Article Note: (miscellaneous) Associate editor: C. Steefel
    Keywords: Advection (Earth sciences) -- Analysis ; Electrolytes -- Analysis
    ISSN: 0016-7037
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Environmental Pollution, Jan, 2013, Vol.172, p.155(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2012.09.004 Byline: Marc Schwientek (a), Hermann Rugner (a), Barbara Beckingham (b), Bertram Kuch (c), Peter Grathwohl (a)(b) Abstract: Water quality of rivers depends often on the degree of urbanization and the population density in the catchment. This study shows results of a monitoring campaign of total concentration of polycyclic aromatic hydrocarbons (PAHs) and suspended particles in water samples in adjacent catchments in Southern Germany with similar geology and climate but different degrees of urbanization. Defined linear relationships between total concentrations of PAHs in water and the amount of suspended solids were obtained indicating predominance of particle-facilitated transport. The slopes of these regressions correspond to the average contamination of suspended particles (C.sub.sus) and thus comprise a very robust measure of sediment pollution in a river. For the first time, we can show that C.sub.sus is distinct in the different catchments and correlates to the degree of urbanization represented by the number of inhabitants per total flux of suspended particles. Author Affiliation: (a) Water & Earth System Science (WESS) Competence Cluster, Keplerstr. 17, 72074 Tubingen, Germany (b) Center of Applied Geoscience, Eberhard Karls University of Tubingen, Holderlinstr. 12, 72074 Tubingen, Germany (c) Institute of Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Bandtale 2, 70569 Stuttgart, Germany Article History: Received 7 June 2012; Revised 24 August 2012; Accepted 8 September 2012
    Keywords: Rivers ; Polycyclic Aromatic Hydrocarbons
    ISSN: 0269-7491
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Environmental Pollution, January 2011, Vol.159(1), pp.133-139
    Description: Fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated along the route of transport in a south German karst system. Atmospheric deposition, seepage water in caves and spring water at the outlet of the catchment were monitored continuously over 1.5 years allowing the establishment of an input/output mass balance at the catchment scale. The results reveal that, even in the highly vulnerable karst catchment, PAHs are effectively retained in the soils. Only during high discharge events, such as snowmelt in spring, increasing PAH concentrations at the outlet of the catchment indicates a mobilization of the pollutants. These events are typically correlated with increasing particle concentrations. Based on our results, we conclude that particle-facilitated transport is the dominating cause of PAH mobilization. In summary, PAHs accumulate over time in soils and only occasionally high discharge events cause a short concentration pulse to be flushed through the karst system. Particle-associated transport is the dominant process for groundwater pollution with polycyclic aromatic hydrocarbons in remote areas.
    Keywords: Atmospheric Deposition ; Particle-Facilitated Transport ; Vulnerability ; Passive Samplers ; Long-Term Monitoring ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 9
    Language: English
    In: Environmental Pollution, 2011, Vol.159(12), pp.3769-3776
    Description: In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m /d, 97/112 mg/m /d, and 1167/1342 mg/m /d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique. ► BTEX compounds contaminated groundwater can be efficiently treated by CWs. ► The removal efficiency depended on CW type, season and contaminant. ► The plant root mat revealed better treatment results than the gravel filter CW. ► Best results achieved by the plant root mat (99% benzene concentration decrease). ► Stable isotope analysis and MPN indicated high benzene remediation potential. Gravel bed constructed wetlands and a plant root mat system efficiently eliminated fuel hydrocarbons (benzene, MTBE) and ammonia-N from groundwater at a pilot-scale.
    Keywords: Btex ; Fuel Hydrocarbon ; Plant Root Mat ; Phytoremediation ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 10
    Language: English
    In: The Science of the Total Environment, August 15, 2014, Vol.490, p.191(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2014.04.110 Byline: Hermann Rugner, Marc Schwientek, Marius Egner, Peter Grathwohl Abstract: Transport of many pollutants in rivers is coupled to mobilization of suspended particles which typically occurs during floods. Since the amount of total suspended solids (TSS) in rivers can be monitored by turbidity measurements this may be used as a proxy for the total concentration of particle associated pollutants such as PAHs, PCBs, etc. and several heavy metals. Online turbidity measurements (e.g. by optical backscattering sensors) would then also allow for an assessment of particle and pollutant flux dynamics if once calibrated against TSS and total pollutant concentrations for a given catchment. In this study, distinct flood and thus turbidity events were sampled at high temporal resolution in three contrasting sub-catchments of the River Neckar in Southwest Germany (Ammer, Goldersbach, Steinlach) as well as in the River Neckar itself and investigated for the total amount of PAHs and TSS in water; turbidity (NTU) and grain size distributions of suspended solids were determined as well. Laboratory experiments were performed with natural river bed sediments from different locations (Ammer) to investigate PAH concentrations, TSS and turbidity during sedimentation of suspended particles under controlled conditions (yielding smaller and smaller suspended particles and TSS with time). Laboratory and field results agreed very well and showed that turbidity and TSS were linearly correlated over an extended turbidity range up to 2000NTU for the field samples and up to 8000NTU in lab experiments. This also holds for total PAH concentrations which can be reasonably well predicted based on turbidity measurements and TSS vs. PAHs relationships -- even for high turbidity values observed during flood events (〉2000NTU). Total PAH concentrations on suspended solids were independent of grain size of suspended particles. This implies that for the rivers investigated the sorption capacity of particles did not change significantly during the observed events. Article History: Received 17 March 2014; Revised 25 April 2014; Accepted 25 April 2014 Article Note: (miscellaneous) Editor: D. Barcelo
    Keywords: Rivers ; Heavy Metals ; Proxy ; Polycyclic Aromatic Hydrocarbons ; Sediments (Geology)
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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