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481.
We present a nitrogen cycle model for pre-industrial times based on an extensive literature database. The model consists of 18 reservoirs in the domains of the atmosphere, land, and ocean. The biotic reservoirs on land and in the ocean (N-fixing plants, non-N-fixing plants, and marine biota) interact with atmospheric N2 and dissolved inorganic nitrogen (DIN, consisting of N2, NO3 ?, and NH4 +) in the ocean and soil waters. Marine DIN is taken up by marine biota and transformed from ocean particulate organic matter to dissolved organic nitrogen and the ocean sediment. The atmosphere, the largest nitrogen reservoir, supplies N2 to the system by N fixation, deposition, and dissolution, and these input fluxes are balanced by denitrification and volatilization back to the atmosphere. The land and ocean domains are linked by river transport, which carries both dissolved and particulate nitrogen to the oceanic coastal zone. The isotope–mass balances of the N reservoirs are calculated from the isotopic composition of the reservoirs and the fractionation factors accompanying the fluxes between the reservoirs based on reported values from different natural conditions. The model sensitivity was tested for different biouptake rates and was run with various human perturbations, including fertilization, nitrous oxide emissions, population-related sewage disposal, land-use changes, and temperature-dependent rate kinetics. The new N mass–isotope cycle model provides the basis for assessment of the impact of artificial fertilization between 1700 and 2050. The perturbation experiments in this study suggest that land-use change is the key factor altering the N mass cycle since industrialization. 相似文献
482.
Caitlin L. Young Iain M. Suthers Daniel D. Johnson Charles A. Gray Faith A. Ochwada-Doyle 《Estuaries and Coasts》2018,41(2):444-452
Lunar phase is regarded as a key driver of reproductive development and spawning activity in prawns, but across smaller-temporal scales, other processes may have a significant influence. Here, we examined the effects of lunar phase and other abiotic variables on the reproductive development of an estuarine-dependent prawn, Metapenaeus bennettae Racek & Dall. We found that turbidity, salinity, water temperature and lunar phase each had a significant independent influence on the likelihood of female prawns being ripe throughout the spawning period. The likelihood of catching a ripe female increased on the new moon and first quarter of the moon and also during conditions of low turbidity, high salinity and high water temperature. For male prawns, however, significant interactions between salinity and lunar phase and also between turbidity and lunar phase were detected. These interactions indicated that salinity and turbidity have variable effects among the different lunar phases. Such complex relationships of reproductive timing and spawning success of M. bennettae, and potentially other aquatic species, are most likely adaptive responses to the highly variable conditions of estuarine environments. 相似文献
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R. T. James McAteer Peter T. Gallagher Jack Ireland C. Alex Young 《Solar physics》2005,228(1-2):55-66
We present an automated approach to active region extraction from full-disc MDI longitudinal magnetograms. This uses a region-growing
technique in conjunction with boundary-extraction to define a number of enclosed contours as belonging to separate regions
of magnetic significance on the solar disc. This provides an objective definition of active regions and areas of plage on
the Sun. A number of parameters relating to the flare potential of each region are discussed. 相似文献
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Stefano Mottola William D. Sears Anders Erikson Alan W. Harris Jim W. Young Gerhard Hahn Mats Dahlgren Beatrice E. A. Mueller Bill Owen Ricardo Gil-Hutton Javier Licandro M. Antonietta Barucci Claudia Angeli Gerhard Neukum Claes-Ingvar Lagerkvist J. Felix Lahulla 《Planetary and Space Science》1995,43(12)
CCD photometry of the NEAR mission fly-by target 253 Mathilde is presented. Measurements taken during 52 nights of observations, from February to June 1995, allow a rotation period of 17.406±0.010 days and a lightcurve amplitude of 0.45±0.02 mag to be determined. A B-V color index of 0.67±0.02 and a V-R of 0.35±0.02 are measured, which are compatible with C-type membership. The determination of the phase relation results in H = 10.28±0.03 and G = 0.12±0.06. Indications that the lightcurve is not strictly singly-periodic are found. A power-spectrum analysis detects a secondary frequency f2 = 0.0322±0.0010 d−1, which is interpreted as evidence for a complex rotation state. 相似文献
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We use Monin-Obukhov similarity theory to extend the Kristensen et al. (1991) aviation gust estimation technique from the neutral to the diabatic surface layer. Example calculations demonstrate the importance of this correction. Simple stability class methods using only standard aviation surface observations are shown to be useful although less accurate and less precise than methods which make full use of Monin-Obukhov similarity results. 相似文献