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  • 1
    Electronic Resource
    Electronic Resource
    Inter-biome comparison of factors controlling stream metabolism (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. We studied whole-ecosystem metabolism in eight streams from several biomes in North America to identify controls on the rate of stream metabolism over a large geographic range. The streams studied had climates ranging from tropical to cool-temperate and from humid to arid and were all relatively uninfluenced by human disturbances.2. Rates of gross primary production (GPP), ecosystem respiration (R) and net ecosystem production (NEP) were determined using the open-system, two-station diurnal oxygen change method.3. Three general patterns in metabolism were evident among streams: (1) relatively high GPP with positive NEP (i.e. net oxygen production) in early afternoon, (2) moderate primary production with a distinct peak in GPP during daylight but negative NEP at all times and (3) little or no evidence of GPP during daylight and a relatively constant and negative NEP over the entire day.4. Gross primary production was most strongly correlated with photosynthetically active radiation (PAR). A multiple regression model that included log PAR and stream water soluble reactive phosphorus (SRP) concentration explained 90% of the variation in log GPP.5. Ecosystem respiration was significantly correlated with SRP concentration and size of the transient storage zone and, together, these factors explained 73% of the variation in R. The rate of R was poorly correlated with the rate of GPP.6. Net ecosystem production was significantly correlated only with PAR, with 53% of the variation in log NEP explained by log PAR. Only Sycamore Creek, a desert stream in Arizona, had positive NEP (GPP: R 〉 1), supporting the idea that streams are generally net sinks rather than net sources of organic matter.7. Our results suggest that light, phosphorus concentration and channel hydraulics are important controls on the rate of ecosystem metabolism in streams over very extensive geographic areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00773.x
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen Dynamics in Forest Soils after Municipal Sludge Additions (1999)
    Springer
    Water, air & soil pollution 112 (1999), S. 259-278 
    Details
    ISSN: 1573-2932
    Keywords: forest ; municipal sludge ; nitrogen ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Nitrogen dynamics were assessed for a forested site in southern New Hampshire during the first and second growing seasons after surface application of an aerobically-digested, limed, liquid municipal sludge. Sludge was applied in June 1989, at 3.3, 6.9, and 14.5 M ha-1 (or 199, 396, and 740 kg TKN ha-1). Elevated net N mineralization (in situ buried bags) occurred in the organic and upper mineral soil horizons during the first two months after sludge application, but was similar to control levels thereafter. Net N mineralization was negligible at 30 and 60 cm soil depths. Foliar N concentration increased with sludge loading rates. Concentrations of NH4+ and NO3- in soil leachate were low, except in early fall when microbial activity was still high and plant demand was low. In trenched subplots where vegetative uptake was eliminated, NO3- concentrations in soil leachate (60 cm) rose to between 15 and 35 mg N L-1 in the first year and remained high in the second year. Other studies reported higher magnitudes of NO3- leaching from treated plots. These studies and the findings reported here shown the characteristics of the sludge being applied to land are at least as important as the physical and chemical characteristics of the site to which they are to be applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005086413282
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical characteristics of leachate from pulp and paper mill residuals used to reclaim a sandy soil (1996)
    Springer
    Water, air & soil pollution 89 (1996), S. 167-187 
    Details
    ISSN: 1573-2932
    Keywords: Pulp and paper mill sludge ; nitrogen ; DOC ; heavy metals ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Primary sludge, secondary sludge, and wood ash from a pulp and paper mill were combined with sand to create a synthetic topsoil (C:N ratio of 18:1) to restore an abandoned gravel pit. Synthetic topsoil was applied to field microcosms at rates equivalent to 0, 2170, 4341, or 6511 kg N/ha; each was seeded with grass. Fifteen chemical constituents in leachate were measured during two field seasons. Cadmium, Ni and Zn were mobilized rapidly by soil disturbance. Chloride and SO4-S eluted rapidly from the sludge along with Na. Nitrate leached with Ca late in each field season when sludge N-mineralization and nitrification exceeded plant uptake and microbial immobilization. Ammonium elution was negligible. Dissolved organic carbon (DOC) was mobilized by decomposition of organic matter in the sludge, as were Mg and K. Copper eluted with DOC, probably as an organic ligand. Lead and ortho-P were below our detection limits. We concluded that a synthetic topsoil with a 30:1 C:N ratio applied at a rate of 2100-4300 kg N/ha should provide adequate plant nutrition while minimizing water quality hazards.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300429
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