9,169 research outputs found

    Emissions of N2O and NO from fertilized fields: summary of available measurement data

    Get PDF
    Information from 846 N2O emission measurements in agricultural fields and 99 measurements for NO emissions was summarized to assess the influence of various factors regulating emissions from mineral soils. The data indicate that there is a strong increase of both N2O and NO emissions accompanying N application rates, and soils with high organic-C content show higher emissions than less fertile soils. A fine soil texture, restricted drainage, and neutral to slightly acidic conditions favor N2O emission, while (though not significant) a good soil drainage, coarse texture, and neutral soil reaction favor NO emission. Fertilizer type and crop type are important factors for N2O but not for NO, while the fertilizer application mode has a significant influence on NO only. Regarding the measurements, longer measurement periods yield more of the fertilization effect on N2O and NO emissions, and intensive measurements (=1 per day) yield lower emissions than less intensive measurements (2–3 per week). The available data can be used to develop simple models based on the major regulating factors which describe the spatial variability of emissions of N2O and NO with less uncertainty than emission factor approaches based on country N inputs, as currently used in national emission inventories

    Human alteration of the global nitrogen and phosphorus soil balances for the period 1970-2050

    Get PDF
    The Millennium Ecosystem Assessment scenarios for 2000 to 2050 describe contrasting future developments in agricultural land use under changing climate. Differences are related to the total crop and livestock production and the efficiency of nutrient use in agriculture. The scenarios with a reactive approach to environmental problems show increases in agricultural N and P soil balances in all developing countries. In the scenarios with a proactive attitude, N balances decrease and P balances show no change or a slight increase. In Europe and North America, the N balance will decline in all scenarios, most strongly in the environment-oriented scenarios; the P balance declines (proactive) or increases slowly (reactive approach). Even with rapidly increasing agricultural efficiency, the global N balance, ammonia, leaching and denitrification loss will not decrease from their current levels even in the most optimistic scenario. Soil P depletion seems to be a major problem in large parts of the global grassland are

    Modelling global annual N2O and NO emissions from fertilized fields

    Get PDF
    Information from 846 N2O emission measurements in agricultural fields and 99 measurements for NO emissions was used to describe the influence of various factors regulating emissions from mineral soils in models for calculating global N2O and NO emissions. Only those factors having a significant influence on N2O and NO emissions were included in the models. For N2O these were (1) environmental factors (climate, soil organic C content, soil texture, drainage and soil pH); (2) management-related factors (N application rate per fertilizer type, type of crop, with major differences between grass, legumes and other annual crops); and (3) factors related to the measurements (length of measurement period and frequency of measurements). The most important controls on NO emission include the N application rate per fertilizer type, soil organic-C content and soil drainage. Calculated global annual N2O-N and NO-N emissions from fertilized agricultural fields amount to 2.8 and 1.6 Mtonne, respectively. The global mean fertilizer-induced emissions for N2O and NO amount to 0.9% and 0.7%, respectively, of the N applied. These overall results account for the spatial variability of the main N2O and NO emission controls on the landscape scal

    Anthropogenic nitrogen autotrophy and heterotrophy of the world's watersheds: Past, present, and future trends

    Get PDF
    Anthropogenic nitrogen autotrophy of a territory is defined as the nitrogen flux associated with local production of harvested crops and grass consumed by livestock grazing (in kg N/km(2)/yr). Nitrogen heterotrophy is the nitrogen flux associated with local food and feed consumption by humans and domestic animals. These two summarizing characteristics (anthropogenic nitrogen autotrophy and heterotrophy (ANAH)) indicate the degree of anthropogenic perturbation of the nitrogen cycle by agriculture and human consumption: their balance value provides information on either the potential for commercial export or the need to import agricultural goods; in a watershed, their vector sum is related to the nitrogen flux delivered to the sea. These indicators were calculated for all the watersheds in the Global Nutrient Export from Watersheds (NEWS) database for 1970 and 2000, as well as for 2030 and 2050, according to Millennium Ecosystem Assessment scenarios. During this 30 year period, many watersheds shifted from relatively balanced situations toward either more autotrophic or more heterotrophic conditions. This trend is predicted to become more pronounced over the next 50 year

    Forecasting with real-time macroeconomic data: the ragged-edge problem and revisions

    Get PDF
    Real-time macroeconomic data are typically incomplete for today and the immediate past (?ragged edge?) and subject to revision. To enable more timely forecasts the recent missing data have to be dealt with. In the context of the U.S. leading index we assess four alternatives,paying explicit attention to publication lags and data revisions.

    Clustering in ICT: From Route 128 to Silicon Valley, from DEC to Google, from Hardware to Content

    Get PDF
    One of the pioneers in academic entrepreneurship and high-tech clustering is MIT and the Route 128/Boston region. Silicon Valley centered around Stanford University was originally a fast follower and only later emerged as a scientific and industrial hotspot. Several technology and innovation waves, have shaped Silicon Valley over all the years. The initial regional success of Silicon Valley started with electro-technical instruments and defense applications in the 1940s and 1950s (represented by companies as Litton Engineering and Hewlett & Packard). In the 1960s and 1970s, the region became a national and international leader in the design and production of integrated circuit and computer chips, and as such became identified as Silicon Valley (e.g. Fairchild Semiconductor, and Intel). In the 1970s and 1980s, Silicon Valley capitalised further on the development, manufacturing and sales of the personal computer and workstations (e.g. Apple, Silicon Graphics and SUN), followed by the proliferation of telecommunications and Internet technologies in the 1990s (e.g. Cisco, 3Com) and Internet-based applications and info-mediation services (e.g. Yahoo, Google) in the late 1990s and early 2000s. When the external and/or internal conditions of its key industries change, Silicon Valley seemed to have an innate capability to restructure itself by a rapid and frequent reshuffling of people, competencies, resources and firms. To characterise the demise of one firm leading, directly or indirectly, to the formation of another and the reconfiguration of business models and product offerings by the larger companies in emerging industries, Bahrami & Evans (2000) introduced the term `flexible recycling.’ This dynamic process of learning by doing, failing and recombining (i.e. allowing new firms to rise from the ashes of failed enterprises) is one of the key factors underlying the dominance of Silicon Valley in the new economy.ICT;Clusters;Networks;Academic entrepreneurship;MIT;Silicon Valley;Stanford University;Flexible recycling;Route 128

    Global nitrogen and phosphate in urban wastewater for the period 1970 to 2050

    Get PDF
    This paper presents estimates for global N and P emissions from sewage for the period 1970-2050 for the four Millennium Ecosystem Assessment scenarios. Using country-specific projections for population and economic growth, urbanization, development of sewage systems, and wastewater treatment installations, a rapid increase in global sewage emissions is predicted, from 6.4 Tg of N and 1.3 Tg of P per year in 2000 to 12.0-15.5 Tg of N and 2.4-3.1 Tg of P per year in 2050. While North America (strong increase), Oceania (moderate increase), Europe (decrease), and North Asia (decrease) show contrasting developments, in the developing countries, sewage N and P discharge will likely increase by a factor of 2.5 to 3.5 between 2000 and 2050. This is a combined effect of increasing population, urbanization, and development of sewage systems. Even in optimistic scenarios for the development of wastewater treatment systems, global N and P flows are not likely to declin

    N:P:Si nutrient export ratios and ecological consequences in coastal seas evaluated by the ICEP approach

    Get PDF
    The Indicator for Coastal Eutrophication Potential (ICEP) for river nutrient export of nitrogen, phosphorus, and silica at the global scale was first calculated from available measurement data. Positive values of ICEP indicate an excess of nitrogen and phosphorus over silica and generally coincide with eutrophication. The sign of ICEP based on measured nutrient fluxes was in good agreement with the corresponding one calculated from the Global-NEWS models for more than 5000 watersheds in the world. Calculated ICEP for the year 2050 based on Global NEWS data for the four Millennium Ecosystem Assessment scenarios show increasing values particularly in developing countries. For further evaluation of the ICEP at the outlet of the rivers of the world based on measurements, there is a need for additional determination silica fluxes and concentrations, which are scarcely documented

    Factors influencing the adoption of mobile services consumers' preferences using analytic hierarchy process

    Get PDF
    The rapid and widespread development of innovations in mobile services is changing societies and improving lives around the world. Due to lagging adoption, many of these new innovations have yet failed to generate revenue that was expected by mobile network operators, application and content developers. There are several factors which are affecting the service adoption by consumers. This paper aims to provide practitioners and academics, an insight on what consumers' preferences are by using an Analytic Hierarchy Approach (AHP). The objective of this paper is to identify factors influencing the adoption of the mobile services. In this study we have considered Payment Mode, Functionality, Added Value and PQCP (perceived quality, cost and performance) as the main service adoption factors. The survey results indicate that Functionality is the most important influencing factor for the respondents, followed by Added Value, PQCP and Payment Mode.Adoption,AHP,Mobile Value Services,Consumer's Preferences

    Bank risk taking and liquidity creation following regulatory interventions and capital support

    Get PDF
    During times of bank distress, authorities often engage in regulatory interventions and provide capital support to reduce bank risk taking. An unintended effect of such actions may be a reduction in bank liquidity creation, with possible adverse consequences for the economy as a whole. This paper tests hypotheses regarding the effects of regulatory interventions and capital support on bank risk taking and liquidity creation using a unique dataset over the period 1999-2009. We find that both types of actions are generally associated with statistically significant reductions in risk taking and liquidity creation in the short run and long run. While the effects of regulatory interventions are also economically significant, the effects of capital support are only economically significant in the long run. Thus, both types of actions have important intended and unintended consequences with implications for policymakers.risk taking;liquidity creation;bank distress;regulatory interventions;capital support
    corecore