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  • 1
    ISSN: 1432-0789
    Keywords: Key words Nitrous oxide ; Nitric oxide ; Organic soil ; Nitrification ; Inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Acetylene, dimethyl ether (DME) and 2-chloro-6-trichloromethyl pyridine (nitrapyrin) were used as inhibitors to study the contributions of nitrification and denitrification to the production of N2O and nitric oxide (NO) in samples taken from the soil profile of a peatland drained for forestry. Acetylene and DME inhibited 60–100% of the nitrification activity in field-moist samples from the 0–5 cm and 5–10 cm peat layers, whereas nitrapyrin had no inhibitory effect. In the 0–5 cm peat layer the N2O production could be reduced by up to 90% with inhibitors of nitrification, but in the 5–10 cm peat layer this proportion was 20–30%. All the inhibitors removed 96–100% of the nitrification potential in peat-water slurries from the 0–5 cm peat layer, but the 5–10 cm layer had a much lower nitrification activity, and here the efficiency of the inhibitors was more variable. Litter was the main net source of NO in the peat profile. NO3 – production was lower in the litter layer than in the peat, whereas N2O production was much higher in the litter than in the peat. Denitrification was the most probable source of N2O and NO in the litter, which had a high availability of organic substrates.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 126-131 
    ISSN: 1432-0789
    Keywords: Organic soil ; Root-derived respiration ; Soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The CO2 released in soil respiration is formed from organic matter which differs in age and stability, ranging from soluble root exudates to more persistent plant remains. The contribution of roots, a relatively fast component of soil cycling, was studied in three experiments. (1) Willows were grown in a greenhouse and CO2 fluxes from the substrate soil (milled peat) and from control peat were measured. (2) CO2 fluxes from various peatland sites were measured at control points and points where the roots were severed from the plants. (3) CO2 fluxes in cultivated grassland established on peatland were measured in grassy subsites and in subsites where the growth of grass was prevented by regular tilling. The root-derived respiration followed the typical annual phenology of the vegetation, being at its maximum in the middle and late summer. All the experiments gave similar results, root-derived respiration accounting for 35–45% of total soil respiration in the middle and late summer at sites with an abundant vegetation. The root-derived respiration from the virgin peatland sites correlated well with the tree biomass, and also partly with the understorey vegetation, but in the drained sites the root effect was greater, even in the presence of less understorey vegetation than at virgin subsites.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 13 (1997), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO2, CH4, and N2O) by roughly 1t CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost-efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈list xml:id="l1" style="custom"〉1In order to study the dynamics of primary production and decomposition in the lake littoral, an interface zone between the pelagial, the catchment and the atmosphere, we measured ecosystem/atmosphere carbon dioxide (CO2) exchange in the littoral zone of an eutrophic boreal lake in Finland during two open water periods (1998–1999). We reconstructed the seasonal net CO2 exchange and identified the key factors controlling CO2 dynamics. The seasonal net ecosystem exchange (NEE) was related to the amount of carbon accumulated in plant biomass.2In the continuously inundated zones, spatial and temporal variation in the density of aerial shoots controlled CO2 fluxes, but seasonal net exchange was in most cases close to zero. The lower flooded zone had a net CO2 uptake of 1.8–6.2 mol m−2 per open water period, but the upper flooded zone with the highest photosynthetic capacity and above-ground plant biomass, had a net CO2 loss of 1.1–7.1 mol m−2 per open water period as a result of the high respiration rate. The excess of respiration can be explained by decomposition of organic matter produced on site in previous years or leached from the catchment.3Our results from the two study years suggest that changes in phenology and water level were the prime cause of the large interannual difference in NEE in the littoral zone. Thus, the littoral is a dynamic buffer and source for the load of allochthonous and autochthonous carbon to small lakes.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 54 (2003), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Drained organic soils contribute substantial amounts of nitrous oxide to the global atmosphere, and we should be able to estimate this contribution. We have investigated when the fluxes of N2O from drained forested or cultivated organic soils could be determined by calculating the fluxes from the concentration gradients of the gas in soil or snow according to Fick's law of diffusion. A static chamber method was applied as a control technique for the gas gradient method. Concentrations of N2O in soil varied from 296 nl l−1 to 8534 nl l−1 during the snow-free periods and were greatest in the early summer. Our results suggest that the gas gradient method can be used to estimate N2O emissions from drained organic soils. There was some systematic difference in the N2O fluxes measured with these two methods, which we attributed to the differences in weather between years 1996 and 1997. In the wet summer of 1996 the chamber method gave greater flux rates than the gas gradient method, and the reverse was true in the dry summer of 1997. In the forest the N2O fluxes measured with the two methods agreed well. The gas gradient is convenient and fast for measuring N2O emissions from fairly dry organic unfrozen soil. In winter the diffusion calculation based on the N2O gradients in snow and the chamber method gave fairly similar flux rates and provided adequate estimates of the fluxes of N2O in winter.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 40 (1998), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Annual and diel variations in methane (CH4) release in stands of Equisetum fluviatile were measured from June to November in Lake Pääjärvi, southern Finland, where E. fluviatile is the dominant emergent macrophyte. An estimate of total annual release of CH4 from stands of E. fluviatile in this lake was also made. Diel variation was measured twice (June and August), whereas measurements for annual variation were performed monthly. The hypothesis that a relationship exists between the productivity of stands and CH4 release was also tested, whereupon net ecosystem exchange (NEE) of CO2 as well as standing stock of E. fluviatile were determined, in addition to simultaneous recordings of air temperature and solar radiation.2. Seasonal variations in CH4 release were pronounced, with the highest release rate of 813 mg m–2 day–1 measured in July and the lowest 6.5 mg m–2 day–1 in November, when the shoreline was already frozen.3. Methane release rates were strongly correlated with mean air temperature in the measuring chambers and with total solar radiation. There was no significant correlation between the instantaneous radiation and CH4 release rates.4. The seasonal patterns of CH4 release and NEE of CO2 resembled each other, except in July when NEE suddenly dropped. The decrease in NEE coincided with the highest CH4 release rate measured and the highest temperature during the measuring period, i.e. 32 °C outside and 37 °C inside the chamber. Excluding this date, daily CH4 release was strongly correlated with NEE (r2 = 0.971).5. No diel changes in CH4 release rates were detected. In June and August the maximum release rates were 11.4 and 16.8 mg CH4 m–2 h–1, respectively.6. The standing stock of E. fluviatile at different times of the growing season was not correlated with CH4 efflux; the CH4 release rates could be related neither to the number of shoots, i.e. sufficient conduits for gas transport were always present, nor to the shoot biomass in the measuring chambers.7. For an estimate of the annual release, the monthly values measured at noon were integrated over the entire growing season; this resulted in 43.7 g CH4 m–2 for the annual emission. The total annual emission of CH4 from the area covered with E. fluviatile in Lake Pääjärvi was calculated to be ≈ 5000 kg.8. Significant amounts of CH4 are released from stands of E. fluviatile in boreal lakes. The CH4 release rate follows a seasonal pattern but there is no diel pattern. Methane release rate can be related to temperature, solar radiation and NEE of CO2, but not to the standing stock of E. fluviatile or the number of shoots.
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  • 7
    ISSN: 0022-4731
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
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  • 8
    ISSN: 1432-0789
    Keywords: Dicyandiamide ; Forest soil ; Mineralization ; Nitrification ; Urea ; Urea-formaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effects of fast- and slow-release organic N fertilizers (urea and urea-formaldehyde, Nitroform) on mineralization, nitrification, and N leaching in an acid, poor forest soil. We also studied the effects of a nitrification inhibitor (dicyandiamide) applied together with urea. Net nitrification, mineralization of N and C were determined by aerobic laboratory incubation of soil samples taken one and three growing seasons after N application. Numbers of autotrophic nitrifiers were estimated by a most probable number method three growing seasons after the treatment. Urea increased the CO2 production immediately after application, but after three growing seasons, CO2 production was the lowest in the urea-treated soils. In the nitroform-treated soils, the concentration of exchangeable NH inf4 sup+ after the first and third growing seasons was of the same magnitude, in contrast to the urea-treated soils, where hydrolysis took place immediately. Three growing seasons after application, the highest amount of NH inf4 sup+ accumulated during the laboratory incubation was in the nitro-form-treated soils. Unlike urea, nitroform did not increase the production of NO inf3 sup- or the number of NH inf4 sup+ oxidizers. In the urea+dicyandiamide-treated soils there was less NO inf3 sup- and a lower number of nitrifiers than in the urea-treated soils. The results showed that a slow-release N fertilizer, such as nitroform, increases the availability of mineral N in acid forest soils without increasing nitrification and hence the risk of NO inf3 sup- leaching.
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  • 9
    ISSN: 1432-0789
    Keywords: Key words Dicyandiamide ; Forest soil ; Mineralization ; Nitrification ; Urea ; Urea-formaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effects of fast- and slow-release organic N fertilizers (urea and urea-formaldehyde, Nitroform) on mineralization, nitrification, and N leaching in an acid, poor forest soil. We also studied the effects of a nitrification inhibitor (dicyandiamide) applied together with urea. Net nitrification, mineralization of N and C were determined by aerobic laboratory incubation of soil samples taken one and three growing seasons after N application. Numbers of autotrophic nitrifiers were estimated by a most probable number method three growing seasons after the treatment. Urea increased the CO2 production immediately after application, but after three growing seasons, CO2 production was the lowest in the urea-treated soils. In the nitroform-treated soils, the concentration of exchangeable NH4 + after the first and third growing seasons was of the same magnitude, in contrast to the urea-treated soils, where hydrolysis took place immediately. Three growing seasons after application, the highest amount of NH4 + accumulated during the laboratory incubation was in the nitroform-treated soils. Unlike urea, nitroform did not increase the production of NO3 – or the number of NH4 + oxidizers. In the urea+dicyandiamide-treated soils there was less NO3 – and a lower number of nitrifiers than in the urea-treated soils. The results showed that a slow-release N fertilizer, such as nitroform, increases the availability of mineral N in acid forest soils without increasing nitrification and hence the risk of NO3 – leaching.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 48 (1997), S. 738-744 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A biofiltration process was developed for styrene-containing off-gases using peat as filter material. The average styrene reduction ratio after 190 days of operation was 70% (max. 98%) and the mean styrene elimination capacity was 12 g m−3 h−1 (max. 30 g m−3 h−1). Efficient styrene degradation required addition of nutrients to the peat, adjustment of the pH to a neutral level and efficient control of the humidity. Maintenance of the water balance was easier in a down-flow than in an up-flow process, the former consequently resulting in much better filtration efficiency. The optimum operation temperature was around 23 °C, but the styrene removal was still satisfactory at 12 °C. Seven different bacterial isolates belonging to the genera Tsukamurella, Pseudomonas, Sphingomonas, Xanthomonas and an unidentified genus in the γ group of the Proteobacteria isolated from the microflora of active peat filter material were capable of styrene degradation. The isolates differed in their capacity to decompose styrene to carbon dioxide and assimilate it to biomass. No toxic intermediate degradation products of styrene were detected in the filter outlet gas or in growing cultures of isolated bacteria. The use of these isolates in industrial biofilters is beneficial at low styrene concentrations and is safe from both the environmental and public health points of view.
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