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  • 1
    Language: English
    In: Science of the Total Environment, 2011, Vol.409(23), pp.4891-4898
    Description: The focus of this article is to combine two main areas of research activities in freshwater ecosystems: the effect of inorganic pollutants on freshwater ecosystems and litter decomposition as a fundamental ecological process in streams. The decomposition of plant litter in aquatic systems as a main energy source in running water ecosystems proceeds in three distinct temporal stages of leaching, conditioning and fragmentation. During these stages metals and metalloids may be fixed by litter, its decay products and the associated organisms. The global-scale problem of contaminated freshwater ecosystems by metals and metalloids has led to many investigations on the acute and chronic toxicity of these elements to plants and animals as well as the impact on animal activity under laboratory conditions. Where sorption properties and accumulation/remobilization potential of metals in sediments and attached microorganisms are quite well understood, the combination of both research areas concerning the impact of higher trophic levels on the modification of sediment sorption conditions and the influence of metal/metalloid pollution on decomposition of plant litter mediated by decomposer community, as well as the effect of high metal load during litter decay on organism health under field conditions, has still to be elucidated. So far it was found that microbes and invertebrate shredder (species of the genera s and ) have a significant influence on metal fixation on litter. Not many studies focus on the impact of other functional groups affecting litter decay (e.g. grazer and collectors) or other main processes in freshwater ecosystems like bioturbation (e.g. , ) on metal fixation/release. ► Metal fixation capacity of litter increases during decay. ► Invertebrate shredders have a significant influence on metal fixation on litter. ► Effects of other functional groups (grazer/collector) have still to be elucidated. ► Only few studies focus on the interaction between bioturbation and metal release. ► The uptake/avoidance of metals by invertebrates is not quite clear.
    Keywords: Biosorption ; Carbon Turnover ; Decay ; Ecosystem Engineers ; Fixation ; Litter Processing ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 2
    Language: English
    In: The Science of the Total Environment, Jan 1, 2013, Vol.442, p.6(4)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2012.10.016 Byline: Jorg Schaller, Carsten Brackhage, Silvia Paasch, Eike Brunner, Ernst Baucker, E. Gert Dudel Keywords: Condensation state; Grass; Plant functional trait; Precipitation; Si cycle;.sup.29Si solid-state NMR Abstract: Silicon is described as beneficial for grasses by enhancing yield and fitness via a considerable contribution to pathogen, drought, and pest resistance. Silicic acid is the predominant form for uptake and transport within the plant and will precipitate in leaves. But it is unknown whether polymeric nanosilicon compounds in its synthetic form, with an increasing concentration in aquatic environments, can be suitable for plant nutrition. Therefore, we investigated the uptake, transport, and deposition of silicic acid/silica within plants using synthetic nanosilica. Our results show a significant difference in silicon (Si) content within the different tissues of Phragmites australis. The nanosilica had been dissolved prior to the uptake by plants. The chemical form of Si during uptake was not traceable. A significant enhancement in the condensation state of the silica was found from root to leaves especially from culm to leaf tips visible by the increasing content of Q.sup.4-groups in the NMR spectra. We conclude that synthetic nanosilica has the same quality as source for the beneficial element Si like natural silica. Since the condensation state is described to control silica solubility, we suggest that different condensation states within the plant may result in different remobilization of silicon during decomposition of the plant material. Article History: Received 28 August 2012; Revised 20 September 2012; Accepted 1 October 2012
    Keywords: Silicon ; Silicon Dioxide ; Precipitation (Meteorology) ; Microbial Drug Resistance
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Chemosphere, 2011, Vol.83(4), pp.627-631
    Description: ► Metal and metalloids were unbound to the exterior surfaces of . ► Metals and metalloid uptake in the gut system is minimalized. ► Gut system including feces significantly affect the metal body content of . Invertebrate shredders such as are key species in contaminated stream ecosystems. Although a number of previous studies examining differences in metal accumulation between the gut system and remaining tissues of invertebrates exist, few focus on wide range of metals and metalloids that are relevant to contaminated systems. This study compared accumulation of the commonest (at study site) 15 metals and metalloids between the gut system including feces and remaining tissues of . All metals and metalloids measured were significantly higher ( 〈 0.001, except Cu 〈 0.005) in the gut system including feces than remaining tissues of . Metals and metalloids in body tissues without the gut system including feces were significantly lower (Al, Cr, Fe and Mn ( 〈 0.005), Sr and U ( 〈 0.01), Co ( 〈 0.05)) in content for a number of elements when compared to washed, whole specimens. As well, all elements measured were significantly higher (all elements ( 〈 0.005) except Cu and Co ( 〈 0.05)) in gut system including feces than washed, whole specimens. These results indicate that in the uptake of all 15 metals and metalloids examined across the gut epithelium is minimalized or that sequestration of these elements in gut epithelial cells may occur.
    Keywords: Bioaccumulation ; Amphipods ; Litter ; Sediment ; Desorption ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 4
    Language: English
    In: Science of the Total Environment, 2011, Vol.409(17), pp.3211-3214
    Description: Organic-rich sediments are known to be effective accumulators for uranium and arsenic. Much is known about the capacity for metal or metalloid fixation by microbes and organic compounds as well as inorganic sediment particles. Experiments investigating the effect of microbes on the process of metal fixation in sediments require sterilized sediments as control treatment which is often realized by gamma-sterilization. Only few studies show that gamma-sterilization has an effect on the remobilization of metal and metalloids and on their physico-chemical properties. These studies deal with sediments with negligible organic content whereas almost nothing is known about organic-rich sediments including a probably high microbial activity. In view of this, we investigated the effect of gamma-sterilization of organic-rich sediments on uranium and arsenic fixation and release. After ten days within an exposure experiment we found a significant higher remobilization of uranium and arsenic in sterile compared to unsterile treatments. In line with these findings the content of dissolved organic carbon (DOC), manganese, and iron increased to even significantly higher concentration in the sterile compared to unsterile treatment. Gamma-sterilization seems to change the physico-chemical properties of organic-rich sediments. Microbial activity is effectively eliminated. From increased DOC concentrations in overlaying water it is concluded that microbes are eventually killed with leaching of cellular compounds in the overlaying water. This decreases the adsorption capacity of the sediment and leads to enhanced uranium and arsenic remobilization. ►Remobilization of uranium and arsenic is higher in gamma-sterile treatments. ►DOC mobilization is also higher in sterilized treatment. ►Adsorption capacity in sediments is reduced by release of DOC.
    Keywords: Gamma-Sterilization ; Doc Release ; Microbes ; Radionuclide ; Metalloids ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 5
    Language: English
    In: Environmental Pollution, 2010, Vol.158(7), pp.2454-2458
    Description: Organic sediments are a main sink for metal pollutants in aquatic systems. However, factors that make sediments a sink of metals and metalloids are still not clear. Consequently, we investigate the role of invertebrate shredders ( L.) on quality of metal and arsenic fixation into organic partitions of sediment in the course of litter decay with laboratory microcosm experiments. During the decomposition of leaf litter, significantly facilitated the development of small particles of organic matter. The capacity of metal fixation was significantly higher in smaller particles than leaf litter and litter residuals. Thus, enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount smaller particles in the aquatic system. Furthermore, invertebrates have a significant effect on formation of dissolved organic matter and remobilization of cobalt, molybdenum and cesium, but no significant effect on remobilization of all other measured elements. enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount of smaller particles in the aquatic system.
    Keywords: Alkaline Mine Water ; Doc ; Biofilm ; Bioremediation ; Invertebrates ; Litter Decay ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 6
    Language: English
    In: Science of the Total Environment, 01 April 2013, Vol.449, pp.63-70
    Description: Increasing arsenic concentrations in freshwater ecosystems is of global concern. Processes affecting arsenic fluxes in catchments are known. These processes are in turn controlled by the underlying geology and air pollution history. In contrast to the knowledge on catchment processes less is known about the hydrochemical processes controlling the fixation/remobilization of arsenic within lakes and artificial reservoirs. Consequently, we examined a reservoir system in the Ore Mts. (Germany) regarding its sink and source potentials affecting arsenic fluxes. This area was faced with heavy deposition inputs from coal burning based acid rain until the beginning of the 1990s. Hereafter concentrations of sulfate and nitrate in runoff waters decreased, whereas dissolved organic carbon (DOC) concentrations are still increasing. Along with this, arsenic concentrations in the water discharge from the catchments increase. Our results reveal that the sediments of the investigated reservoir system contain high inventories of arsenic in association with ferric and organic phases. A nitrate deficit dependent arsenic release is suggested. It is indicated that arsenic release from the reservoir sediments may be controlled by water nitrate concentration, which in turn is dependent on the nitrate concentration in the runoff water from the catchment. ► We examine increasing dissolved arsenic in water reservoirs. ► Arsenic release from sediments was controlled by decreasing water nitrate concentration. ► Basin sediment arsenic was found in ferric and humic matter. ► A long term trend of arsenic in water is negatively related to nitrate.
    Keywords: Arsenic Fluxes ; Iron ; Metalloid ; Nitrate ; Sediments ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 7
    Language: English
    In: Science of the Total Environment, 01 January 2013, Vol.442, pp.6-9
    Description: Silicon is described as beneficial for grasses by enhancing yield and fitness via a considerable contribution to pathogen, drought, and pest resistance. Silicic acid is the predominant form for uptake and transport within the plant and will precipitate in leaves. But it is unknown whether polymeric nanosilicon compounds in its synthetic form, with an increasing concentration in aquatic environments, can be suitable for plant nutrition. Therefore, we investigated the uptake, transport, and deposition of silicic acid/silica within plants using synthetic nanosilica. Our results show a significant difference in silicon (Si) content within the different tissues of . The nanosilica had been dissolved prior to the uptake by plants. The chemical form of Si during uptake was not traceable. A significant enhancement in the condensation state of the silica was found from root to leaves especially from culm to leaf tips visible by the increasing content of Q -groups in the NMR spectra. We conclude that synthetic nanosilica has the same quality as source for the beneficial element Si like natural silica. Since the condensation state is described to control silica solubility, we suggest that different condensation states within the plant may result in different remobilization of silicon during decomposition of the plant material. ► Silicon precipitation occurs in tissues with transpiration function. ► Silica condensation state in grass depends on dominant function of the tissue. ► Nanosilica is mainly dissolved prior to uptake.
    Keywords: Condensation State ; Grass ; Plant Functional Trait ; Precipitation ; Si Cycle ; 29si Solid-State NMR ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 8
    Language: English
    In: Environmental and Experimental Botany, April, 2012, Vol.77, p.283(5)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envexpbot.2011.12.009 Byline: Jorg Schaller, Carsten Brackhage, E. Gert Dudel Keywords: Cellulose; Lignin; Macrophytes; Poaceae; Secondary metabolism; Silica Abstract: a* Silicon availability changes the cellulose, lignin and phenol content of grasses. a* Silicon surplus affect the cellulose content: reduced (culm) and enhanced (leaf). a* Silicon addition altered phenol content: decreased (leaf) and increased (culm). a* Only weak silicon to lignin interaction was found. Author Affiliation: Institute of General Ecology and Environmental Protection, University of Technology Dresden, PF 1117, 01737 Tharandt, Germany Article History: Received 23 February 2011; Revised 11 November 2011; Accepted 10 December 2011
    Keywords: Grasses ; Silicon ; Lignin ; Cellulose ; Phenols (Class of compounds)
    ISSN: 0098-8472
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Water, Air, & Soil Pollution, 2011, Vol.218(1), pp.227-233
    Description: Many studies were conducted measuring the lethal concentration of pollutants by using a contaminated solution or polluted sediments. Considering the impact of polluted food on mortality and uptake quantity of invertebrate shredders in batch cultures, little is known about, e.g. uranium and cadmium. Consequently, we investigated in situ the impact of metal and metalloid polluted food and water on Gammarus pulex L. under nature-like conditions. In contrast to other publications, a very low mortality rate of the invertebrates was found. Furthermore, fixation of elements by G. pulex was shown to be low compared to initial concentrations. Fixation of non essential metals and metalloids is shown to take place mainly on the surface of the invertebrates. This is deduced from easy desorption of a relevant amount of fixed metals and metalloids. It is concluded that the accumulation of metals and metalloids in situ under nature-like conditions within the food web via invertebrate shredders is very low. The invertebrates seem to minimize the uptake of non essential elements in the presence of nutrient-rich food even in habitats with higher contamination levels. Hence, invertebrates seem to be adapted to higher contamination levels in their favourable habitats.
    Keywords: Fixation ; Avoidance ; Invertebrates ; Leaf litter ; Chemical speciation ; Desorption kinetics
    ISSN: 0049-6979
    E-ISSN: 1573-2932
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  • 10
    Language: English
    In: Chemosphere, 2010, Vol.79(2), pp.169-173
    Description: Organic sediments are known to be a significant sink of inorganic elements in polluted freshwater ecosystems. Hence, we investigated the role of invertebrate shredders (the freshwater shrimp L.) in metal and arsenic enrichment into organic partitions of sediments in a wetland stream at former uranium mining site. Metal and metalloid content in leaf litter increased significantly during decomposition, while at the same time the carbon content decreased. During decomposition, . as a ecosystem engineer facilitated significantly the enrichment of magnesium (250%), manganese (560%), cobalt (310%), copper (200%), zinc (43%), arsenic (670%), cadmium (100%) and lead (1340%) into small particle sizes. The enrichments occur under very high concentrations of dissolved organic carbon. Small particles have high surface area that results in high biofilm development. Further, the highest amounts of elements were observed in biofilms. Therefore, invertebrate shredder like . can enhance retention of large amounts of metal and arsenic in wetlands.
    Keywords: Heavy Metal ; Arsenic ; Decay ; Invertebrates ; Leaf Litter ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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