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  • Geologic Sediments
  • 1
    Language: English
    In: Science of the Total Environment, 15 August 2014, Vol.490, pp.191-198
    Description: 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 ( ) 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 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 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, and turbidity during sedimentation of suspended particles under controlled conditions (yielding smaller and smaller suspended particles and with time). Laboratory and field results agreed very well and showed that turbidity and were linearly correlated over an extended turbidity range up to 2000 NTU for the field samples and up to 8000 NTU in lab experiments. This also holds for total PAH concentrations which can be reasonably well predicted based on turbidity measurements and vs. PAHs relationships — even for high turbidity values observed during flood events (〉 2000 NTU). 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.
    Keywords: Pollutant Fluxes in Rivers ; Turbidity ; Total Suspended Solids ; Particle Facilitated Transport ; Polycyclic Aromatic Hydrocarbons ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 2
    Language: English
    In: Environmental Pollution, January 2013, Vol.172, pp.155-162
    Description: 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 ( ) and thus comprise a very robust measure of sediment pollution in a river. For the first time, we can show that 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. ► PAHs in water samples show a linear correlation with the total suspended solids. ► PAHs on suspended solids correspond to mean concentrations in sediments sampled. ► Degree of urban pressure per particle flux drives PAH loads on suspended particles. ► Dilution of particle associated pollutants requires “clean background” particles. Particle-facilitated transport of PAHs was found to relate to urban population pressure relative to suspended particle loading in contrasting catchments.
    Keywords: Polycyclic Aromatic Hydrocarbons ; Land Use ; Suspended Solids ; Water Quality ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 3
    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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  • 4
    Language: English
    In: Environmental science & technology, 01 August 2004, Vol.38(15), pp.4169-75
    Description: Desorption experiments were carried out in flow through columns following long-term sorption batch experiments (up to 1010 days at 20 degrees C; Rügner, 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 degrees C. The temperature was raised after that stepwise from originally 20 to 30, 40, 50, and finally to 70 degrees 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(-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 degrees C to compare sorption and desorption enthalpies. Both were in good agreement, confirming that desorption was not significantly different from sorption.
    Keywords: Fresh Water -- Chemistry ; Geologic Sediments -- Chemistry ; Phenanthrenes -- Chemistry
    ISSN: 0013-936X
    E-ISSN: 15205851
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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