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Berlin Brandenburg

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  • 1
    Language: English
    In: Environmental Pollution, 2010, Vol.158(10), pp.3272-3278
    Description: In a lysimeter experiment, topsoils were polluted with filter dust from a non-ferrous metal smelter and then planted with trees. Sequential extractions were used to follow the changes in metal fractionation of Cu, Zn, Cd, and Pb over 42 months. Plant-free and uncontaminated soils served as reference. In the contaminated and planted soils, the largest changes in speciation occurred within the first 6 months. The relative amounts of certain metal fractions were linearly related to each other, indicating systematic redistribution between fractions. The results indicate that under natural conditions with high heterogeneity in total metal contents spatial differences are more important than temporal variations in determining the fractionation and solubility of metals in contaminated soils. In the absence of plants soils exhibited a completely different fractionation 30 months after pollution, with much higher proportions in the more refractory phases. This suggests that plant activity kept the metals in a more soluble form. Plant activity has kept contaminating metals in a more soluble state than in plant-free soils over 30 months.
    Keywords: Soil ; Heavy Metals ; Phytostabilization ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 2
    Language: English
    In: Environmental Pollution, 2010, Vol.158(5), pp.1955-1962
    Description: By using a rhizobox micro-suction cup technique we studied in-situ mobilization and complexation of Zn and Cd in the rhizosphere of non-hyperaccumulating and two different ecotypes, one of them hyperaccumulating Zn, the other Zn and Cd. The dynamic fraction (free metal ions and small labile complexes) of Zn and Cd decreased with time in the rhizosphere solution of the respective hyperaccumulating ecotypes, and at the end of the experiment, it was significantly smaller than in the other treatments. Furthermore, the rhizosphere solutions of the ecotypes exhibited a higher UV absorptivity than the solution of the rhizosphere and the plant-free soil. Based on our findings we suggest that mobile and labile metal-dissolved soil organic matter complexes play a key role in the rapid replenishment of available metal pools in the rhizosphere of hyperaccumulating ecotypes, postulated earlier. A mechanism that explains the rapid replenishment of metal pools accessible by hyperaccumulator plants for phytoextraction is proposed.
    Keywords: Cadmium ; Zinc ; Hyperaccumulator ; Thlaspi ; Rhizosphere ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 3
    Language: English
    In: Biogeochemistry, 2016, Vol.130(1), pp.117-131
    Description: The formation and turnover of soil organic matter (SOM) includes the biogeochemical processing of the macronutrient elements nitrogen (N), phosphorus (P) and sulphur (S), which alters their stoichiometric relationships to carbon (C) and to each other. We sought patterns among soil organic C, N, P and S in data for c. 2000 globally distributed soil samples, covering all soil horizons. For non-peat soils, strong negative correlations (p 〈 0.001) were found between N:C, P:C and S:C ratios and % organic carbon (OC), showing that SOM of soils with low OC concentrations (high in mineral matter) is rich in N, P and S. The results can be described approximately with a simple mixing model in which nutrient-poor SOM (NPSOM) has N:C, P:C and S:C ratios of 0.039, 0.0011 and 0.0054, while nutrient-rich SOM (NRSOM) has corresponding ratios of 0.12, 0.016 and 0.016, so that P is especially enriched in NRSOM compared to NPSOM. The trends hold across a range of ecosystems, for topsoils, including O horizons, and subsoils, and across different soil classes. The major exception is that tropical soils tend to have low P:C ratios especially at low N:C. We suggest that NRSOM comprises compounds selected by their strong adsorption to mineral matter. The stoichiometric patterns established here offer a new quantitative framework for SOM classification and characterisation, and provide important constraints to dynamic soil and ecosystem models of carbon turnover and nutrient dynamics.
    Keywords: Carbon ; Nitrogen ; Phosphorus ; Protein ; Soil organic matter ; Stoichiometry ; Sulphur
    ISSN: 0168-2563
    E-ISSN: 1573-515X
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  • 4
    In: Rapid Communications in Mass Spectrometry, 30 June 2012, Vol.26(12), pp.1475-1480
    Description: RATIONALE: Stable isotopes of nitrogen in nitrate (NO(3)(-)) are frequently used to identify nitrate sources and to study nitrogen (N) transformation processes, but the measurement methods available are generally rather labor intensive and/or costly, and dissolved organic matter (DOM) can interfere with the δ(15)N signature of nitrate. We therefore have developed a simple cleanup procedure for freshwater samples with low nitrate and high DOM concentrations.METHODS: Nitrate and DOM are extracted from a freeze-dried water sample by using a concentrated sodium hydroxide solution. By the subsequent addition of acetone, two liquid layers are formed, and nitrate migrates into the acetone while DOM remains in the concentrated NaOH solution, thus separating the nitrate from the DOM. For nitrogen isotope analysis, purified nitrate salts are combusted at 1030 °C to produce N(2) gas in an elemental analyzer (EA) coupled to an isotope ratio mass spectrometer (IRMS).RESULTS: With this novel technique up to 99% of DOM could be removed from river water and soil solutions. The method has been tested for sample amounts as small as 4 µmol NO(3)(-) with a precision of 〈0.1‰ (1SD). Nitrate standards are reproduced accurately without any blank correction.CONCLUSIONS: The benefits of this method are the lack of interferences derived from DOM on the δ(15)N signature and the ease of sample preparation.
    Keywords: Chemistry;
    ISSN: 0951-4198
    E-ISSN: 1097-0231
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  • 5
    In: Rapid Communications in Mass Spectrometry, 30 October 2011, Vol.25(20), pp.3056-3062
    Description: The nitrogen (δN) and oxygen isotope (δO) analysis of nitrate (NO) from aqueous samples can be used to determine nitrate sources and to study N transformation processes. For these purposes, several methods have been developed; however, none of them allows an accurate, fast and inexpensive analysis. Here, we present a new simple method for the isolation of nitrate, which is based on the different solubilities of inorganic salts in an acetone/hexane/water mixture. In this solvent, all major nitrate salts are soluble, whereas all other oxygen‐bearing compounds such as most inorganic carbonates, sulfates, and phosphates are not. Nitrate is first concentrated by freeze‐drying, dissolved in the ternary solvent and separated from insoluble compounds by centrifugation. Anhydrous barium nitrate is then precipitated in the supernatant solution by adding barium iodide. For δO analysis, dried Ba(NO) samples are directly reduced in a high‐temperature conversion system to CO and measured on‐line using isotope ratio mass spectrometry (IRMS). For δN analysis, samples are combusted in an elemental analyzer (EA) coupled to an IRMS system. The method has been tested down to 20 µmol NO with a reproducibility (1SD) of 0.1‰ for nitrogen and 0.2–0.4‰ for oxygen isotopes. For nitrogen we observed a small consistent N enrichment of +0.2‰, probably due to an incomplete precipitation process and, for oxygen, a correction for the incorporation of water in the precipitated Ba(NO) has to be applied. Apart from being robust, this method is highly efficient and low in cost. Copyright © 2011 John Wiley & Sons, Ltd.
    Keywords: Chemistry;
    ISSN: 0951-4198
    E-ISSN: 1097-0231
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  • 6
    Language: English
    In: Biogeosciences, Nov 27, 2018, Vol.15(22), p.7043
    Description: pSemi-terrestrial soils such as floodplain soils are considered potential hot spots of nitrous oxide (N.sub.2 O) emissions. Microhabitats in the soil - such as within and outside of aggregates, in the detritusphere, and/or in the rhizosphere - are considered to promote and preserve specific redox conditions. Yet our understanding of the relative effects of such microhabitats and their interactions on N.sub.2 O production and consumption in soils is still incomplete. Therefore, we assessed the effect of aggregate size, buried leaf litter, and plant-soil interactions on the occurrence of enhanced N.sub.2 O emissions under simulated flooding/drying conditions in a mesocosm experiment. We used two model soils with equivalent structure and texture, comprising macroaggregates (4000-250thinsp;#xC2;#xB5;m) or microaggregates (250thinsp;#xC2;#xB5;m) from a N-rich floodplain soil. These model soils were planted with basket willow (Salix viminalis L.), mixed with leaf litter or left unamended. After 48thinsp;h of flooding, a period of enhanced N.sub.2 O emissions occurred in all treatments. The unamended model soils with macroaggregates emitted significantly more N.sub.2 O during this period than those with microaggregates. Litter addition modulated the temporal pattern of the N.sub.2 O emission, leading to short-term peaks of high N.sub.2 O fluxes at the beginning of the period of enhanced N.sub.2 O emission. The presence of S. viminalis strongly suppressed the N.sub.2 O emission from the macroaggregate model soil, masking any aggregate-size effect. Integration of the flux data with data on soil bulk density, moisture, redox potential and soil solution composition suggest that macroaggregates provided more favourable conditions for spatially coupled nitrification-denitrification, which are particularly conducive to net N.sub.2 O production. The local increase in organic carbon in the detritusphere appears to first stimulate N.sub.2 O emissions; but ultimately, respiration of the surplus organic matter shifts the system towards redox conditions where N.sub.2 O reduction to N.sub.2 dominates. Similarly, the low emission rates in the planted soils can be best explained by root exudation of low-molecular-weight organic substances supporting complete denitrification in the anoxic zones, but also by the inhibition of denitrification in the zone, where rhizosphere aeration takes place. Together, our experiments highlight the importance of microhabitat formation in regulating oxygen (O.sub.2) content and the completeness of denitrification in soils during drying after saturation. Moreover, they will help to better predict the conditions under which hot spots, and "hot moments", of enhanced N.sub.2 O emissions are most likely to occur in hydrologically dynamic soil systems like floodplain soils.
    Keywords: Nitrification – Analysis ; Nitrification – Environmental Aspects ; Soil Structure – Analysis ; Soil Structure – Environmental Aspects ; Soils – Analysis ; Soils – Environmental Aspects ; Denitrification – Analysis ; Denitrification – Environmental Aspects ; Nitrous Oxide – Analysis ; Nitrous Oxide – Environmental Aspects
    ISSN: 1726-4170
    E-ISSN: 17264189
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  • 7
    Language: English
    In: Journal of Plant Nutrition and Soil Science, 06/2011, Vol.174(3), pp.408-419
    ISSN: Journal of Plant Nutrition and Soil Science
    E-ISSN: 14368730
    E-ISSN: 15222624
    Source: Wiley (via CrossRef)
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  • 8
    Language: English
    In: Biogeosciences Discussions, 07/02/2018, pp.1-23
    ISSN: Biogeosciences Discussions
    E-ISSN: 1810-6285
    Source: CrossRef
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  • 9
    Language: English
    In: Soil Biology and Biochemistry, 2006, Vol.38(7), pp.1745-1756
    Description: We assessed the effects of chronic heavy metal (HM) contamination on soil microbial communities in a newly established forest ecosystem. We hypothesized that HM would affect community function and alter the microbial community structure over time and that the effects are more pronounced in combination with acid rain (AR). These hypotheses were tested in a model forest ecosystem consisting of several tree species (Norway spruce, birch, willow, and poplar) maintained in open top chambers. HMs were added to the topsoil as filter dust from a secondary metal smelter and two types of irrigation water acidity (ambient rain vs. acidified rain) were applied during four vegetation periods. HM contamination strongly impacted the microbial biomass (measured with both fumigation–extraction and quantitative lipid biomarker analyses) and community function (measured as basal respiration and soil hydrolase activities) of the soil microbial communities. The most drastic effect was found in the combined treatment of HM and AR, although soil pH and bioavailable HM contents were comparable to those of treatments with HM alone. Analyses of phospholipid fatty acids (PLFAs) and terminal restriction fragment length polymorphisms (T-RFLPs) of PCR-amplified 16S ribosomal DNA showed that HM treatment affected the structure of bacterial communities during the 4-year experimental period. Very likely, this is due to the still large bioavailable HM contents in the HM contaminated topsoils at the end of the experiment.
    Keywords: Heavy Metals ; Acid Rain ; Model Forest Ecosystems ; Soil Microbial Communities ; Plfa Profiles ; T-Rflp ; Genetic Fingerprinting ; 16s Rrna Gene ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 10
    Language: English
    In: Environmental Pollution, 2008, Vol.152(3), pp.559-568
    Description: Root systems of Norway spruce ( ) and poplar ( ) were long-term exposed to metal-contaminated soils in open-top chambers to investigate the accumulation of the heavy metals in the fine roots and to assess the plants suitability for phytostabilisation. The heavy metals from the contaminated soil accumulated in the fine roots about 10–20 times more than in the controls. The capacity to bind heavy metals already reached its maximum after the first vegetation period. Fine roots of spruce tend to accumulate more heavy metals than poplar. Copper and Zinc were mainly detected in the cell walls with larger values in the epidermis than in the cortex. The heavy metals accumulated in the fine roots made up 0.03–0.2% of the total amount in the soils. We conclude that tree fine roots adapt well to conditions with heavy metal contamination, but their phytostabilisation capabilities seem to be very low. Long-term exposed fine roots of trees are well adapted to soils with high heavy metal contents, but their phytostabilisation capabilities are rather low.
    Keywords: Fine Roots ; Heavy Metals ; Norway Spruce ; Phytostabilisation ; Poplar ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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