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121.
The HBV-N model was used for a scenario analysis of changes in nitrogen retention and transport caused by alterations of
wetness due to land drainage, lowering of lakes, building of dams and climatic variability in a river basin in south-central
Sweden (1885–1994). In general, dams were situated in locations more favourable for retention, compared to the lowered lakes.
Rather modest conversions of water bodies only changed nitrogen transport by about 3%. The 180-times-larger increase of (mainly)
tile-drained agricultural land had, according to simulations, increased the nitrogen transport by 17%, due to reduced retention.
However, compared to human-induced alteration of the landscape N retention, the choice of 10-year periods of climatological
data had the overriding effect on the calculated nitrogen transport. Weather-induced variations resulted in a 13% difference
in nitrogen retention between various 10-year periods. When the model was driven by climatological data from the driest 10-year
period (1905–1914), the estimated average annual load was only half of that obtained with climatological data from the wettest
10-year period (1975–1984).
Electronic Publication 相似文献
122.
中国NOx控制制度研究 总被引:2,自引:0,他引:2
中国NOx污染呈现总量逐年增加的趋势,已成为大气污染治理的主要内容.从NOx的控制制度、排放指标上对我国现行NOx控制体系进行了分析,并对我国进一步完善NOx控制制度及标准提出了建议.主要建议有(1)降低NOx控制标准适应当前环境状况;(2)应用科学方法,制订合理的NOx总量控制标准和制度;(3)制订氮氧化物排放标准;(4)浓度控制和总量控制结合.总量控制的实施要注意污染物排放标准制定的政策取向;总量控制法的基本原理和程序;总量控制结合排放标准控制. 相似文献
123.
124.
Marine bacterial community plays a vital role in the formation of the hypoxia zone in coastal oceans. Yet, their dynamics in the seasonal hypoxia zone of the Bohai Sea(BHS) are barely studied. Here, the 16S r RNA gene-based high-throughput sequencing was used to explore the dynamics of their diversity, structure, and function as well as driving factors during the gradual deoxygenation process in the BHS. Our results evinced that the bacterial community was dominated by Proteobacteria, followed b... 相似文献
125.
126.
Martin Braniš 《Water, Air, & Soil Pollution: Focus》2008,8(1):49-60
To assess the effect of changes in traffic density and fuels used for heating at the beginning of the 1990s, 1992–2005 monthly
averages of PM10, SO2, NO2, NO, CO and O3 from Prague, the Czech capital, were analyzed together with long term trends in emissions of major pollutants, fuel consumption
and number of vehicles registered in Prague. The data from all monitoring stations were retrieved from the database of the
state automated monitoring system. Correlation coefficients between ambient monthly averaged temperature and all pollutants
of concern showed distinct seasonal trends. The results showed that while SO2 and to some extent also CO concentrations dropped namely in the first half of the analyzed period (1992–1997) as a result
decreased fossil fuel consumption for local heating, the behaviour of other pollutant concentrations followed a different
pattern. PM10 concentrations decreased during the beginning of the 1990s but showed a sign of increase after 2000. Concentrations of ozone
and NO2 did not reveal any significant change throughout the whole studied period. It can be concluded that during the studied period
traditional urban sources of pollution, such as coal and oil combustion, lost their importance but were simultaneously substituted
by pollutants from automotive transport (namely PM and NO2) making the problem of air quality even worse. 相似文献
127.
Brian P. Leaderer Rebecca T. Zagraniski Jan A. J. Stolwijk 《Environmental management》1977,1(1):31-37
A method is presented here by which the actual numbers of individuals in the U.S. population who would be expected to suffer respiratory illness as a result of exposure to ambient nitrogen dioxide (NO2) concentrations in excess of the Federally-designated ambient air quality standard can be estimated. At the same time we have attempted to quantify how these adverse health effects would be alleviated by various degrees of reductions in current ambient concentrations. In addition, the health benefit expected to be derived by various NOx emission control strategies will be examined utilizing the health benefit estimation method presented.It is estimated that there were approximately 33.2×106 excess cases of respiratory illnesses in the U.S. in 1973 associated with ambient NO2 concentrations in excess of the national ambient standard. A reduction of approximately 50 to 60 percent below 1973 NO2 levels is needed to essentially eliminate excess respiratory illness associated with ambient NO2 concentration. 相似文献
128.
European scale application of atmospheric reactive nitrogen measurements in a low-cost approach to infer dry deposition fluxes 总被引:1,自引:0,他引:1
Y.S. Tang I. Simmons N. van Dijk C. Di Marco E. Nemitz U. Dmmgen K. Gilke V. Djuricic S. Vidic Z. Gliha D. Borovecki M. Mitosinkova J.E. Hanssen T.H. Uggerud M.J. Sanz P. Sanz J.V. Chorda C.R. Flechard Y. Fauvel M. Ferm C. Perrino M.A. Sutton 《Agriculture, ecosystems & environment》2009,133(3-4):183
A European scale network was established in 2006 as part of the NitroEurope Integrated Project to infer reactive nitrogen (Nr) dry deposition fluxes, based on low-cost sampling of gaseous and aerosol species and inferential modelling. The network provides monthly measurements of NH3, NH4+, HNO3 and NO3−, as well as SO2, SO42−, HCl, Cl− and base cations at 58 sites. Measurements are made with an established low-cost denuder methodology (DELTA) as a basis to: (1) examine temporal trends and spatial patterns across Europe, (2) improve and calibrate inferential modelling techniques to estimate exchange of Nr species, (3) provide best estimates of atmospheric dry N deposition, and (4) permit an analysis of net GHG exchange in relation to atmospheric and agricultural N inputs at the European scale. Responsibility for measurements is shared among seven European laboratories. An inter-comparison of the DELTA implementation by 6 laboratories at 4 test sites (Montelibretti, Italy; Braunschweig, Germany; Paterna, Spain and Auchencorth, UK) from July to October 2006 provided training for the laboratories and showed that good agreement was achieved in different climatic conditions (87% of laboratory site-means within 20% of the inter-laboratory median). Results obtained from the first year of measurements show substantial spatial variability in atmospheric Nr concentrations, illustrating the major local (NH3) and regional (HNO3, NO3−, and NH4+) differences in Nr concentrations. These results provide the basis to develop future estimates of site-based Nr dry deposition fluxes across Europe, and highlight the role of NH3, largely of agricultural origin, which was the largest single constituent and will dominate dry Nr fluxes at most sites. 相似文献
129.
Impacts of atmospheric pollution on the plant communities of British acid grasslands 总被引:1,自引:0,他引:1
Payne RJ Stevens CJ Dise NB Gowing DJ Pilkington MG Phoenix GK Emmett BA Ashmore MR 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2602-2608
Air pollutants are recognised as important agents of ecosystem change but few studies consider the effects of multiple pollutants and their interactions. Here we use ordination, constrained cluster analysis and indicator value analyses to identify potential environmental controls on species composition, ecological groupings and indicator species in a gradient study of UK acid grasslands. The community composition of these grasslands is related to climate, grazing, ozone exposure and nitrogen deposition, with evidence for an interaction between the ecological impacts of base cation and nitrogen deposition. Ozone is a key agent in species compositional change but is not associated with a reduction in species richness or diversity indices, showing the subtly different drivers on these two aspects of ecosystem degradation. Our results demonstrate the effects of multiple interacting pollutants, which may collectively have a greater impact than any individual agent. 相似文献
130.
异养硝化及其在污水脱氮中的作用 总被引:23,自引:0,他引:23
通过与传统自养硝化作用的比较,异养硝化作用不仅是客观存在的过程,而且某些特殊的异养菌,可以同步进行异养硝化和好氧反硝化,对于污水脱氮具有重要的理论意义和应用价值。 相似文献