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  • Heavy Metals
  • 1
    Language: English
    In: Nutrient Cycling in Agroecosystems, 2012, Vol.93(1), pp.75-88
    Description: Topsoil constituents are eroded from agricultural sites and leached towards drainage channels. This transfer can affect aquatic ecosystems and deteriorate the efficiency of drainage systems and fertilisers. As long as erosion cannot be completely avoided, the recycling of sediments and associated nutrients may offer a sustainable solution to these problems. The aim of our case study at the island Sant Erasmo, lagoon of Venice (Italy) was to assess the ecological problems and potentials of sediment recycling. With our assessment we concentrated on (1) the origin of channel sediments, (2) the benefit of sediment application for increasing the nutrient stocks of the soils, and (3) the risk of heavy metal (HM) contamination of arable soils by sediment application. Samples from soils of horticultural sites, sediments, and waters from adjacent drainage channels and lagoon sediments were analyzed for the concentrations of nutrients (P and K) and HM (Cu, Pb, and Zn). Potentially available channel sediment masses and element stocks were calculated for the soil fertility classes of Sant Erasmo based on local measurements of sediment depths and analyses of aerial photographs by a geographic information system. In a column experiment, leaching of both nutrients and Cu from recently dredged sediments was analyzed. Heavy metal concentrations of soils and channel sediments were much higher than of lagoon sediments. The similarity of the chemical properties of the channel sediments and of top soil samples implies that topsoil material is eroded into the channels. The amount of sediments accumulated in the channels corresponded to soil erosion rates between 2 and 23 t ha −1  a −1 . Channel sediments contained higher concentrations of nutrients and organic carbon but slightly lower concentrations of HM than the soils of adjacent horticultural sites. Sediment P and K yields would be sufficient to replace fertiliser application at the horticultural sites for up to 51 and 35 years, respectively. The column experiment indicated that Cu mobilization induced by oxidation processes is restricted to the first years after sediments are applied to the soils. Our study emphasizes that for a comprehensive assessment of sediment recycling in agricultural systems the available sediment stocks as well as the contents of nutrients and pollutants of the sediment in relation to soils have to be considered.
    Keywords: Phosphorus ; Heavy metals ; Nutrient cycling ; Leaching experiment
    ISSN: 1385-1314
    E-ISSN: 1573-0867
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  • 2
    Language: English
    In: Journal of environmental quality, 2009, Vol.38(3), pp.933-9
    Description: Liming is a common technique suggested for the stabilization of shooting range sites. We investigated the effect of an increase in pH on the mobilization of soluble and dispersible (colloidal) Pb, As, and Sb. Our hypothesis was that the addition of divalent cations counteracts the pH-induced mobilization of soluble and colloidal metal(loid)s. We determined soluble (operationally defined as the fraction 〈 10 nm obtained after centrifugation) and dispersible (filter cut-off 1200 nm) As, Pb, Sb, Fe, and C(org) concentrations in the filtered suspensions of batch extracts of topsoil samples (C(org): 8%) from a former shooting range site following a pH increase to values between 3.5 and 7 by adding a monovalent (KOH) or a divalent (Ca(OH)(2)) base. In the Ca(OH)(2)-treated samples, dissolved metal(loid) concentrations were 62 to 98% lower than those titrated with KOH to similar pH. Similarly, Ca reduced the concentration of dispersible Pb by 95%, but had little or no impact on dispersible As and Sb. We conclude that the counterion valency controls the mobility of metal(loid)s by affecting the mobility and sorption capacity of the sorbents (e.g., colloids, organic matter).
    Keywords: Antimony -- Chemistry ; Arsenic -- Chemistry ; Cations, Divalent -- Chemistry ; Lead -- Chemistry ; Soil -- Analysis
    ISSN: 0047-2425
    E-ISSN: 15372537
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  • 3
    Language: English
    In: Journal of environmental quality, 2007, Vol.36(4), pp.1187-93
    Description: Drying of soil may increase the hydrophobicity of soil and affect the mobilization of colloids after re-wetting. Results of previous research suggest that colloid hydrophobicity is an important parameter in controlling the retention of colloids and colloid-associated substances in soils. We tested the hypothesis that air-drying of soil samples increases the hydrophobicity of water-dispersible colloids and whether air-drying affects the mobilization of colloid-associated heavy metals. We performed batch experiments with field-moist and air-dried (25 degrees C) soils from a former sewage farm (sandy loam), a municipal park (loamy sand), and a shooting range site (loamy sand with 25% C(org)). The filtered suspensions (〈1.2 microm) were analyzed for concentrations of dissolved and colloidal organic C and heavy metals (Cu, Cd, Pb, Zn), average colloid size, zeta potential, and turbidity. The hydrophobicity of colloids was determined by their partitioning between a hydrophobic solid and a hydrophilic aqueous phase. Drying increased hydrophobicity of the solid phase but did not affect the hydrophobicity of the dispersed colloids. Drying decreased the amount of mobilized mineral and (organo-)mineral colloids in the sewage farm soils but increased the mobilization of organic colloids in the C-rich shooting range soil. Dried samples released less colloid-bound Cd and Zn than field-moist samples. Drying-induced mobilization of dissolved organic C caused a redistribution of Cu from the colloidal to the dissolved phase. We conclude that drying-induced colloid mobilization is not caused by a change in the physicochemical properties of the colloids. Therefore, it is likely that the mobilization of colloids in the field is caused by increasing shear forces or the disintegration of aggregates.
    Keywords: Desiccation ; Hydrophobic and Hydrophilic Interactions ; Colloids -- Chemistry ; Metals, Heavy -- Analysis ; Soil -- Analysis
    ISSN: 0047-2425
    E-ISSN: 15372537
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  • 4
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2004, Vol.167(2), pp.177-183
    Description: Risk assessment of heavy metal input into forest ecosystems requires information about metal fluxes from the forest floor (organic layer) into the mineral soil. Common methods for the monitoring of element fluxes are generally time‐consuming and expensive. Additionally, the reliability of the results is in part contested especially for trace elements, showing very low concentrations which are sometimes even below analytical detection limit. We used ion exchange resin tubes installed below the forest floor to determine heavy metal and As fluxes at 25 forest monitoring sites in Germany. Chloride tracer experiments and the comparison of our data with throughfall and lysimeter data, determined within the Level II monitoring network, proved the accuracy of our method. Mean trace element fluxes based on the resin method were 50 g As ha yr, 2 g Cd ha yr, 168 g Cu ha yr, 176 g Ni ha yr, and 186 g Pb ha yr.The results show that the organic layer may change into a source of heavy metals after emission has decreased. Austauscherharzröhren zur Bestimmung des Spurenelementeintrags in Mineralböden auf Waldstandorten Der Schwermetalleintrag von der Humusauflage in den Mineralboden ist eine wichtige Größe zur Risikoabschätzung der Schwermetallflüsse in Waldökosystemen. Herkömmliche Methoden zur Erfassung von Elementflüssen sind zeit‐ und kostenaufwändig. Bei Spurenelementen verringern analytische Probleme die Aussagekraft der ermittelten Daten. Mithilfe von Röhren, die mit Ionenaustauscherharz gefüllt sind und unterhalb der Humusauflage in den Boden eingebracht werden, haben wir auf 25 Waldstandorten Schwermetall‐ und As‐Flüsse gemessen. Chlorid‐Tracer‐Experimente und der Vergleich unserer Daten mit Stoffflussdaten aus dem Level‐II‐Monitoring bestätigen, dass mit unserer Methode Elementflüsse von der Humusauflage in den Mineralboden zuverlässig erfasst werden können. Mit den Austauscherharzröhren haben wir folgende durchschnittliche Elementflüsse bestimmt: 50 g As ha a, 2 g Cd ha a, 168 g Cu ha a, 176 g Ni ha a und 186 g Pb ha a. Die Ergebnisse zeigen, dass die Humusauflage nach Rückgang anthropogener Einträge zur Schwermetallquelle wird.
    Keywords: Heavy Metals ; Arsenic ; Forest Soils ; Element Fluxes ; Exchange Resin Tubes
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 5
    Language: English
    In: Geoderma, 2004, Vol.123(1), pp.153-162
    Description: Use of soil archives provides the opportunity to retrospectively analyze changes in soil properties. We used the distribution of heavy metals between the exterior and interior of aggregates in recent and archived samples to derive (1) temporal trends in metal concentrations and distribution across aggregates and (2) to assess aggregate turnover times. We collected 11 topsoils under grassland and forest along a transect from Moscow to a distance of 50 km from the city centre and at a background location. Furthermore, we analyzed six topsoils sampled between 1910 and 1954 at some of the locations. We fractionated aggregates 〉1 cm into interior and exterior portions. Except at one contaminated site, heavy metal concentrations were low (Cd: 0.09-0.33 mg kg (super -1) , Cu: 6.8-24 mg kg (super -1) , Pb: 6.7-31 mg kg (super -1) , Zn: 25-54 mg kg (super -1) ), comparable with background levels in central Europe. They were not related to the distance to Moscow indicating that Moscow was no point source for the studied soils. During the last century, contents of heavy metals in soils increased inside and decreased outside the city. In Moscow, the heavy metal accumulation in the aggregate exterior relative to the interior was more pronounced in recent than in archived samples reflecting a higher recent than historic deposition. However, there was also an increase in heavy metal concentrations in the interior of recent compared with archived aggregates. Thus, the studied aggregates were turned over at least once during the last 50-90 years at all sites. This limited the build-up of metal concentration gradients in aggregates.
    Keywords: Archived Soil Samples ; Heavy Metals ; Soil Aggregates ; Small-Scale Heterogeneity ; Aggregate Stability ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 6
    Language: English
    Description: Benetzungshemmung ist eine zentrale Steuergröße für den bevorzugten Wasser- und Stofftransport im Boden. Die vorliegende Arbeit untersucht den Einfluss der Benetzungshemmung auf die Stoff- und Wasserflüsse in einem schadstoffbelasteten ehemaligen Rieselfeld. Des Weiteren untersucht diese Arbeit den Einfluss der Benetzungshemmung auf das Mobilisierungspotential von Schwermetallen und PAHs im Dispergierungsversuch. Wir überprüften, ob der bevorzugte Fluss das Risiko einer Grundwasserbelastung senkt, da benetzungsgehemmte Bodenpartien umflossen werden, oder erhöht, da hydraulische Scherkräfte in präferentiellen Fließwegen eine Mobilisierung von kolloid-gebundenen Schadstoffen bewirken können (1). Darüber hinaus gehen wir davon aus, dass benetzungsgehemmte Bodenpartien reaktionsträge sind und daher weniger als Schadstoffquelle fungieren als benetzbare Bereiche (2). Des Weiteren nehmen wir an, dass die Ausbildung einer zeitlich stabiler Benetzungshemmung die Bildung und Stabilität der Fließwege (3) und damit die Sammeleffizienz von Platten-Lysimetern beeinflusst (4) Die erste Hypothese wurde getestet, indem der langfristige und räumliche Verlauf der Stoffflüsse im Sickerwasser mittels freidränenden Lysimetern und Dochtlysimetern analysiert wurde und physikalisch-chemische Faktoren identifiziert wurden, die die Mobilität von gelösten und kolloid-gebundenen Schadstoffen im Boden kontrollieren (1). Die zweite Hypothese wurde getestet, indem die Auswirkungen der Boden-Hydrophobizität auf das Mobilisierungspotenzial von Schadstoffen im Labor-Dispergierungsversuch ermittelt wurden (2). Der Einfluss der Bodenfeuchte auf die Bildung und Stabilität der Fließwege wurde... ; Water repellency has been found to be a crucial parameter in controlling preferential transport of water and solutes in the soil. This thesis investigates the impact of water repellency on solute and water fluxes in a contaminated former sewage site. Moreover this thesis examines the impact of water repellency on the mobilisation potential of heavy metals and PAHs by dispersion experiments. We tested the hypothesis whether preferential flow decreases the risk of groundwater contamination, since water repellent soil parts are bypassed, or if it increases, since hydraulic shear forces may cause a rapid downward transport of colloid-bound contaminants through the vadose zone (1). Moreover we assume that hydrophobic compounds are chemically inert and therefore act to a lesser extend as a source for contaminants than hydrophilic compounds (2). Furthermore we suppose that the moisture-related temporal and spatial extend and severity of water repellency influences the formation and stability of preferential flow paths (3) and hence the collection performance of plate lysimeters (4). To address the first hypothesis the long-term spatial and temporal course of solute fluxes sampled by zero-tension and tension lysimeters are analysed and physico-chemical factors which control the mobility of dissolved and colloid-bound contaminants in the soil are...
    Keywords: Naturwissenschaften Und Mathematik ; Hydrophobizität ; Lysimeter ; Preferentieller Fluß ; Schadstoffmobilität ; Schwermetalle ; Contaminant Mobility ; Heavy Metals ; Lysimeter ; Preferential Flow ; Water Repellency
    Source: DataCite
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