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  • 1
    Language: English
    In: Environmental science & technology, 15 January 2013, Vol.47(2), pp.701-9
    Description: As a proxy to trace the impact of anthropogenic activity, sedimentary polycyclic aromatic hydrocarbons (PAHs) are compared between the early industrialized and newly industrialized countries of Germany and China, respectively. Surface sediment samples in the Ammer River of Germany and the Liangtan River of China were collected to compare concentration levels, distribution patterns, and diagnostic plots of sedimentary PAHs. Total concentrations of 16 PAHs in Ammer sediments were significantly higher by a factor of ~4.5 than those in Liangtan. This contrast agrees with an extensive literature survey of PAH levels found in Chinese versus European sediments. Distribution patterns of PAHs were similar across sites in the Ammer River, whereas they were highly varied in the Liangtan River. Pyrogenic sources dominated in both cases. Strong correlations of the sum of 16 PAHs and PAH groups with TOC contents in the Liangtan River may indicate coemission of PAHs and TOC. Poor correlations of PAHs with TOC in the Ammer River indicate that other factors exert stronger influences. Sedimentary PAHs in the Ammer River are primarily attributed to input of diffuse sources or legacy pollution, while sediments in the Liangtan River are probably affected by ongoing point source emissions. Providing further evidence of a more prolonged anthropogenic influence are the elevated black carbon fractions in sedimentary TOC in the Ammer compared to the Liangtan. This implies that the Liangtan River, like others in newly industrialized regions, still has a chance to avoid legacy pollution of sediment which is widespread in the Ammer River and other European waterways.
    Keywords: Geologic Sediments -- Analysis ; Polycyclic Aromatic Hydrocarbons -- Analysis ; Rivers -- Chemistry ; Water Pollutants, Chemical -- Analysis ; Water Pollution, Chemical -- Analysis
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 2
    Language: English
    In: Environmental Science & Technology, 08/2004, Vol.38(15), pp.4169-4175
    Description: Desorption experiments were carried out in flow through columns following long-term sorption batch experiments (up to 1010 days at 20 degree C; Ruegner, H.; Kleineidam, S.; Grathwohl, P. Long-term sorption kinetics of phenanthrene in aquifer materials. Environ. Sci. Technol. 1999, 33, 1645-1651) to elucidate sorption/desorption hysteresis phenomena of phenanthrene in aquifer materials. Most of the sorbents employed in this study (homogeneous lithocomponents separated from aquifer sediments or fresh rock fragments) showed highly nonlinear sorption isotherms because of coal particles embedded inside the grains. Because sorption capacities were high, sorption equilibrium was not reached in most of the sorbents during the initial sorptive uptake experiments lasting up to 1010 days. Desorption was studied up to 90 days at 20 degree C. The temperature was raised after that stepwise from originally 20 to 30, 40, 50, and finally to 70 degree C for selected samples to estimate activation energies of desorption. A numerical intraparticle pore diffusion model was used to fit sorptive uptake data and subsequently for pure forward prediction of the release rates in the desorption column experiments. Desorption was initially fast followed by extended tailing which in other studies is fitted by using multirate first-order models. Our results demonstrate that the retarded intraparticle pore diffusion model can predict the desorption rates with a single diffusion rate constant obtained independently from the long-term batch sorption experiment. No evidence for hysteresis was found, suggesting that many hysteresis phenomena reported earlier are experimental artifacts resulting from nonequilibrium effects and "nonphysical" models. The different temperature steps allowed one to additionally calculate activation energies of desorption (45-59 kJ mol super(-1)), which were in reasonably good agreement with results from earlier studies for a retarded pore diffusion process. In addition, equilibrium sorption isotherms were determined at 20 and 40 degree C to compare sorption and desorption enthalpies. Both were in good agreement, confirming that desorption was not significantly different from sorption.
    Keywords: Aquifers ; Enthalpy ; Desorption ; Temperature ; Hysteresis ; Groundwater Pollution ; Coal ; Model Studies ; Pores ; Equilibrium ; Rocks ; Kinetics ; Absorption ; Mine Wastes ; Isotherms ; Aquifers ; Enthalpy ; Desorption ; Temperature ; Hysteresis ; Groundwater Pollution ; Coal ; Model Studies ; Pores ; Equilibrium ; Rocks ; Kinetics ; Absorption ; Mine Wastes ; Isotherms ; Sources and Fate of Pollution ; Water Quality;
    ISSN: 0013-936X
    E-ISSN: 1520-5851
    Source: American Chemical Society (via CrossRef)
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  • 3
    Language: English
    In: Environmental Science & Technology, 05/1999, Vol.33(10), pp.1645-1651
    Description: Most aquifer materials are heterogeneous in terms of grain size distribution and petrography. To understand sorption kinetics, homogeneous subfractions, either separated from heterogeneous sands and gravels (lithocomponents) or fragments of fresh rocks, have to be studied. In this paper we present data on long-term sorption kinetics of phenanthrene for homogeneous samples consisting of one type of lithocomponents or fresh rock fragments in different grain sizes. Diffusion rate constants were determined in batch experiments using a numerical model for retarded intraparticle pore diffusion and correlated to grain size and intraparticle porosity of the lithocomponents. Sorption isotherms were nonlinear for all samples investigated (Kleineidam et al. (1)). The numerical model described the sorption kinetics very well for coarse sand and gravels. Tortuosity factors, which were obtained as final fitting factors, agreed with Archie's law predictions based on the intraparticle porosity. The dependency of sorptive uptake on grain size revealed that for smaller grains intrasorbent diffusion may become significant. This is attributed to relatively large particulate organic matter (POM) within the sedimentary rock fragments. Specifically, charcoal and coal particles, which were found in some of the sandstones, controlled the sorptive uptake rates.
    Keywords: Geochemistry Of Rocks, Soils, And Sediments ; Environmental Geology ; Aquifers ; Aromatic Hydrocarbons ; Charcoal ; Clastic Rocks ; Clastic Sediments ; Coal ; Coarse-Grained Materials ; Diffusion ; Experimental Studies ; Fragments ; Geochemistry ; Grain Size ; Gravel ; Ground Water ; Homogeneous Materials ; Hydrocarbons ; Kinetics ; Laboratory Studies ; Numerical Models ; Organic Compounds ; Particulate Materials ; Phenanthrene ; Physicochemical Properties ; Pollution ; Polycyclic Aromatic Hydrocarbons ; Sand ; Sandstone ; Sedimentary Rocks ; Sediments ; Sorption;
    ISSN: 0013-936X
    E-ISSN: 1520-5851
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  • 4
    Language: English
    In: Environmental Science & Technology, 05/1999, Vol.33(10), pp.1637-1644
    Description: Remediation of groundwater contamination in unconsolidated aquifers by dissolved hydrophobic compounds (HOC) requires detailed information on the sorption parameters present in the sediments. Equilibrium sorption isotherms were measured for phenanthrene for a wide variety of lithocomponents (constituents of sand and gravel sediments) and unweathered rock fragments (limestones and sandstones). The lithocomponents were separated based on macroscopic appearance of different lithologies (e.g. limestones, sandstones, shales, mudstones, and igneous rocks) and characterized in terms of organic carbon content and specific surface area. In addition the organic matter (OM) was characterized using coal petrography methods (white and UV light microscopy). As confirmed by heat-treated samples sorption was solely due to OM. Organic carbon normalized sorption coefficients (K sub(OC)) varied by almost 3 orders of magnitude among the samples investigated. The different origin and maturity of isolated organic matter (organic facies) is believed to be responsible. For example, extremely high K sub(OC) values were found for particulate organic matter such as charcoal and coal particles which were preserved within the sandstone and limestone grains. In a second paper we report data on sorption kinetics of the samples used in this study (1).
    Keywords: Chemical Equilibrium ; Sediment Pollution ; Particulate Organic Matter ; Pollutant Persistence ; Adsorption ; Groundwater Pollution ; Aquifers ; Sediment Pollution ; Sorption ; Limestone ; Organic Matter ; Remediation ; Groundwater Pollution ; Geology ; Aquifers ; Sorption ; Rocks ; Water Pollution Treatment ; Organic Matter ; Remediation ; Groundwater Pollution ; Isotherms ; Phenanthrene ; Hydrophobic Compounds ; Physics and Chemistry ; Characteristics, Behavior and Fate ; Sources and Fate of Pollution ; Freshwater Pollution ; Hydrophobic Compounds ; Phenanthrene;
    ISSN: 0013-936X
    E-ISSN: 1520-5851
    Source: American Chemical Society (via CrossRef)
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