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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 14 (1976), S. 0 
    ISSN: 1745-6584
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Energietechnik , Geologie und Paläontologie
    Notizen: An individual home waste nitrogen and phosphorus removal system was evaluated in the laboratory. The gravity flow system consisted of a 10 × 60 cm (4 × 24 in) vertical Plainfield sand column followed by a series of 8 × 32 cm (3 × 12 in) horizontal columns filled with calcite (CaCO3) or dolomite (Ca MgCO3). Nitrogen removal was attempted using a nitrification-denitrification system where methanol was used as an energy source and P removal was attempted using calcite and dolomite. Separate experiments running from 4 to 6 months were used to test various diameter calcite and dolomite. The phosphorus removal system was also the site of denitrification and hence was in an anaerobic environment. Nitrogen removal was successful with approximately 60–100% removal in a 1-day residence time after methanol addition. Increased denitrification rates were observed using smaller diameter filling materials but no differences were observed between equal-diameter calcite and dolomite. Phosphorus removal was successful initially but after approximately one month, the ability of the calcite or dolomite to sorb phosphorus was curtailed in a 3-day residence time. Results indicated that calcite was superior to dolomite and smaller diameter material was superior to larger diameter in removing phosphorus. However, it appeared that slime growth and organic anion competition covering the sorption sites on the calcite and dolomite prevented significant phosphorus removal after the first 2 to 3 months.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 15 (1977), S. 0 
    ISSN: 1745-6584
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Energietechnik , Geologie und Paläontologie
    Notizen: Results of this study indicate that the nitrate and chloride concentrations in the ground water of the central Wisconsin sand plains are significantly above background, and that the main source is the irrigated agriculture in the region. Nitrate-N concentrations ranged from nil to 56 mg/1 and chloride from nil to 68 mg/1. Nitrate-N concentrations exceeded 10 ppm in 15 of 33 irrigation wells and in 2 of 3 domestic wells. Nitrate-N and chloride concentrations varied widely between adjacent wells but the CI/NO3-N ratio was much less variable. This suggests similar relative inputs of nitrogen and chloride presumably from nitrogen and potassium (potassium chloride) fertilizers.The study was conducted at three levels of intensity; a small field during one growing season, a University Experimental Farm over several years, and many local farms during part of a growing season. Differences in concentrations of nitrate-N and chloride in the surface of the ground water underlying the moderately fertilized potato field closely reflected the fertilizer and irrigation management on different parts of the field during that season. This detailed study of one field showed that solute transit times through the 16 feet (5 m) of unsaturated zone to the surface of the ground water are less than a year.Differences in concentration of nitrate-N and chloride between irrigation wells on the Experimental Farm closely reflected the irrigation and fertilizer practices on surrounding fields. Nitrate-N and chloride concentrations in ground water were lower where the adjacent land had been idle for many years and only recently cropped. However, levels were high where fertilizer and irrigation inputs.On a larger scale, the nitrate-N and chloride concentrations in area farmer irrigation wells were as different between wells on the same farm as farm as between the various farms.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 9 (1973), S. 0 
    ISSN: 1752-1688
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Notizen: : Renewed (de novo) synthesis of methane gas was shown to occur when samples of lake sediment were dispersed on glass beads and incubated in a helium atmosphere at 23°C. Under the above conditions, sediment samples from hardwater and softwater lakes generated up to 440 nanomoles and 80 nanomoles per ml of sediment per two days, respectively. At the time of collection, sediment samples possessed approximately similar amounts of “native” methane. Nitrate, sulfate, and acetylene were shown to suppress methane synthesis by sediment incubated as described.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 9 (1973), S. 0 
    ISSN: 1752-1688
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Notizen: : A study was conducted to elucidate some of the chemical factors affecting the rate and pathways of N transformations in lake sediments. The main emphasis was placed on modifying a noncalcareous sediment with CaCO3 to approximate the composition of a calcareous sediment. Additionally, the effects of Ca2+, CO32-, Mg2+ and OH- were evaluated by using appropriate chemicals. Further, the effect of aluminum sulfate was evaluated with both sediment types. Sediment pH at 7 days was not affected by CaCO3, but was decreased by aluminum sulfate. The CaCO3 treatment increased the rate of ammonification, nitrification, reduction of acetylene to ethylene and methane formation, while with few exceptions the other treatments decreased the rate of the transformations studied. Aluminum sulfate, which has been proposed as a lake restoration treatment, increased ammonification but decreased most of the other transformations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 10 (1974), S. 0 
    ISSN: 1752-1688
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Notizen: : To investigate the magnitude of denitrification and assimilatory nitrate reduction as these reactions relate to the fate of nitrate reaching sediments via groundwater seepage, undisturbed core samples of sediments (40 cm length) from two lakes (Mendota and Tomahawk) were leached from the bottom (at 1.4 cm/day) with a solution of 15N-nitrate (10 mg N/liter). The sediment columns were fitted with Pt electrodes to measure the oxidation-reduction (Eh) potential. While leaching removed considerable ammonium-N and soluble organic N, essentially no 15N had passed through the columns by 50 days. The Eh readings indicated that denitrification was occurring in the lower portions of the columns. The 15N distribution of the sediment N after 50 days showed that about 15 to 26% of the added nitrate-N was converted to organic N and ammonium-N. The data show that denitrification can be a significant N sink in seepage lakes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 233 (1971), S. 66-67 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Lake sediments, being highly reduced and rich in organic matter, are ideal for denitrification. Fermentation gases emanating from lake sediments contain large volumes of molecular nitrogen, presumably biogenic in origin3 and denitrifying microorganisms have been identified in marine and lake ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 211 (1966), S. 892-893 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Five grams of 〈 2 mm soil is placed in a 125-ml. Erlenmeyer flask, 30 ml. of water is added, and the soil-water mixture boiled under reflux for 60 min, using a rheostat-controlled electric hot-plate. Twenty millilitres of 10 per cent (w/v) solution of potassium sulphate is added to the cooled ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 229 (1971), S. 42-42 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Nitrate-nitrogen was determined in 210 limestone samples from quarries throughout Wisconsin. Major geological formations sampled were Niagara (Silurian), Galena Black River (Ordovician), Lower Magnesian (Ordovician), and Men-dota (Cambrian) dolomites. Determinations were made with the ...
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 1 (1985), S. 3-7 
    ISSN: 1432-0789
    Schlagwort(e): Nitrification ; Denitrification ; Soil profile
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Nitrous oxide (N2O) fluxes at the soil surface and concentrations at 0.1, 0.2, and 0.3 m were determined in a 40-year-old planted tallgrass (XXX) prairie, a 40-year-old white pine (Pinus strobus) plantation, and field plots treated annually for 18 years either with 33 metric tons of manure ha−1 (330 kg N ha−1) and NH4NO3 (80 kg N ha−1) or with only NH4NO3 (control). Nitrous oxide fluxes from the prairie, forest, manure-amended, and control sites from 13 May to 10 November 1980 ranged from 0.2 to 1.3, 3.5 to 19.5, 3.7 to 79.0, and 1.7 to 24.8 ng N2O-N m−2s−1, respectively. We observed periods when there was no apparent relationship between the N2O flux from the surface and N2O concentrations in the soil profile. This was generally the case in the prairie and in the field sites following the application of N fertilizer. The N2O concentrations in the soil profile increased markedly and coincided with increased soil water content following periods of heavy rainfall for all sites except the prairie. Nitrous oxide concentration gradients indicate that following heavy rainfalls the site of N2O production was moved from the surface deeper into the soil profile. We suggest that the source of N2O production near the surface is nitrification and that N2O is produced by denitrification of NO3 leached into the soil following heavy rainfall.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 14 (1992), S. 116-120 
    ISSN: 1432-0789
    Schlagwort(e): Freezing and thawing of soils ; Nitrogen mineralization ; Microbial biomass ; Ninhydrin-reactive N
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In humid regions of the United States there is considerable interest in the use of late spring (April–June) soil NO 3 − concentrations to estimate fertilizer N requirements. However, little information is available on the environmental factors that influence soil NO 3 − concentrations in late winter/early spring. The influence of freeze-thaw treatments on N mineralization was studied on several central Iowa soils. The soils were subjected to temperatures of-20°C or 5°C for 1 week followed by 0–20 days of incubation at various temperatures. The release of soluble ninhydrin-reactive N, the N mineralization rate, and net N mineralization (mineral N flush) were observed. The freeze-thaw treatment resulted in a significant increase in the N mineralization rate and mineral N flush. The N mineralization rate in the freeze-thaw treated soils remained higher than in non-frozen soils for 3–6 days when thawed soils were incubated at 25°C and for up to 20 days in thawed soils incubated at 5°C. The freeze-thaw treatments resulted in a significant release of ninhydrin-reactive N. These values were closely correlated with the mineral N flush (r 2=0.84). The release of ninhydrin-reactive N was more closely correlated with biomass N (r 2=0.80) than total N (r 2=0.65). Our results suggest that freeze-thaw events in soil disrupt microbial tissues in a similar way to drying and re-wetting or chloroform fumigation. Thus the level of mineral N released was directly related to the soil microbial biomass. We conclude that net N mineralization following a spring thaw may provide a significant portion of the total NO 3 − present in the soil profile.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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