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Wilfried Winiwarter Jan Willem Erisman James N. Galloway Zbigniew Klimont Mark A. Sutton 《Climatic change》2013,120(4):889-901
Human activities affect the impact of the nitrogen cycle on both the environment and climate. The rate of anthropogenic nitrogen fixation from atmospheric N2 may serve as an indicator to the magnitude of this impact, acknowledging that relationship to be effect-dependent and non-linear. Building on the set of Representative Concentration Pathway (RCP) scenarios developed for climate change research, we estimate anthropogenic industrial nitrogen fixation throughout the 21st century. Assigning characteristic key drivers to the four underlying scenarios we arrive at nitrogen fixation rates for agricultural use of 80 to 172 Tg N/yr by 2100, which is slightly less to almost twice as much compared with the fixation rate for the year 2000. We use the following key drivers of change, varying between scenarios: population growth, consumption of animal protein, agricultural efficiency improvement and additional biofuel production. Further anthropogenic nitrogen fixation for production of materials such as explosives or plastics and from combustion are projected to remain considerably smaller than that related to agriculture. While variation among the four scenarios is considerable, our interpretation of scenarios constrains the option space: several of the factors enhancing the anthropogenic impact on the nitrogen cycle may occur concurrently, but never all of them. A scenario that is specifically targeted towards limiting greenhouse gas emissions ends up as the potentially largest contributor to nitrogen fixation, as a result of large amounts of biofuels required and the fertilizer used to produce it. Other published data on nitrogen fixation towards 2100 indicate that our high estimates based on the RCP approach are rather conservative. Even the most optimistic scenario estimates that nitrogen fixation rate will remain substantially in excess of an estimate of sustainable boundaries by 2100. 相似文献
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ten Hallers-Tjabbes CC Wegener JW Van Hattum B Kemp JF ten Hallers E Reitsemae TJ Boon JP 《Marine environmental research》2003,55(3):203-233
The presence and the development of imposex were investigated in the common whelk (Buccinum undatum) and the red whelk (Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (< 63 microm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of > or = 100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (> 10 ships day(-1)), intermediate (5--10 ships day(-1)), and low (< 5 ships day(-1)). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction < 63 microm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea. 相似文献
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M. G. Mennen H. J. M. A. Zwart J. E. M. Hogenkamp J. W. Erisman 《Boundary-Layer Meteorology》1996,81(3-4):353-371
Flow distortion errors on wind and friction velocity induced by a box simulating the housing of a gas analyzer used in dry
deposition eddy correlation measurements were determined in a field experiment. ‘Undisturbed’ and ‘disturbed’ wind and friction
velocities, measured with two dry deposition monitoring systems run simultaneously, were compared, one to the other. In the
‘disturbed’ case the box was mounted below the 3-component probe of the sonic anemometer of one of these systems, while in
the ‘undisturbed’ case the box was removed. When the probe was located on the upstream side of the box, the results showed
satisfactory agreement with theoretical estimates using Wyngaard’s potential-flow approach and a spherical model for the box.
This model can be applied to obtain first-order corrections for flow distortion errors induced by cubic-like (or spherical)
obstacles such as a gas analyzer housing used in dry deposition research systems, or to determine the optimal location of
this housing relative to the sonic probe in such systems. When the probe was located halfway downstream and halfway to the
side of the box, the experimental flow distortion errors did not exceed those for the upstream case. This implies that to
keep flow distortion errors in dry deposition systems as small as possible the sonic probe can be placed upstream but also
to the side of the gas analyzer housing. The results of our experiments also confirmed that correcting for flow distortion
with the commonly used tilt equations yields underestimated values. 相似文献
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Wet deposition of ammonium in Europe 总被引：2，自引：0，他引：2
Ammonium concentration data in precipitation have been compiled to derive a concentration and deposition field for ammonium in Europe. Measurements referring to a total number of 218 measuring sites have been considered. Because of changes in the ammonium concentrations due to the use of improper sampling procedures, a correction procedure is proposed. This makes allowance for the type of sampler used, the length of the sampling period, and whether or not light-protected sample bottles are used. Dependent on the specific sampling procedure used correction factors range from 0.75 to 1.20. According to our calculations, the total wet deposition flux of ammonium in Europe in the early 1980s amounts to 2.4 Mt NH4
+y-1. However, for some parts of Europe the flux cannot be estimated very reliably because of the low number or even the absence of measuring sites. Compared to earlier estimates for around 1960, the ammonium wet deposition flux has increased by approximately 25% during the period 1960–1980. 相似文献
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An automated system for measuring the dry deposition fluxes of SO2 on a routine basis based on the micrometeorological gradient technique has been developed for application over grassland and other short vegetation. The ability of the system to determine turbulent exchange parameters such as the friction velocity u
* and the heat flux H was investigated by comparison with an automated eddy correlation system.Determinations of u
* and H by both methods have generally been found to be in very good agreement for 20 min averages. Aerodynamic resistances derived from both systems showed no systematic differences but individual values differed considerably. From the analysis it appeared that in addition to classical rejection criteria on wind speed and inhomogeneity, etc., periods with large shifts in wind direction also have to be removed from the data set before interpretation. 相似文献
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