The nitrogen cycle, scientific uncertainty and policy relevant science

Much of the research on the nitrogen cycle aims to improving scientific understanding but is not focused specifically on removing or reducing the scientific uncertainties that constrain policy makers in the formulation of appropriate responses to old or emerging environmental problems. Policy makers, for example, commonly find it difficult to assess the spatial or temporal importance of the various risks to human and ecosystem health that stem from man's interference with the natural N cycle. This paper will justify this conclusion by reference to the findings of a recent study on non-point pollution from crop production in China. The findings concern the perceived risks of groundwater nitrate to human health; uncertainties about critical NOX levels and their interactions with other pollutants; various other dimensions of man's impact on the N cycle. The paper will go on to suggest a more systematic process or pathway by which scientists can select and design their research in a manner that could give more effective support to policy makers.     

The nitrogen cycle,scientific uncertainty and policy relevant science

Much of the research on the nitrogen cycle aims to improving scientific understanding but is not focused specifically on removing or reducing the scientific uncertainties that constrain policy makers in the formulation of appropriate responses to old or emerging environmental problems. Policy makers, for example, commonly find it difficult to assess the spatial or temporal importance of the various risks to human and ecosystem health that stem from man’s interference with the natural N cycle. This paper will justify this conclusion by reference to the findings of a recent study on non-point pollution from crop production in China. The findings concern the perceived risks of groundwater nitrate to human health; uncertainties about critical NO_x levels and their interactions with other pollutants; various other dimensions of man’s impact on the N cycle. The paper will go on to suggest a more systematic process or pathway by which scientists can select and design their research in a manner that could give more effective support to policy makers.     

Plans of mice and men: from bench science to science policy

The transition from bench science to science policy is not always a smooth one, and my journey stretched as far as the unemployment line to the hallowed halls of the U.S. Capitol. While earning my doctorate in microbiology, I found myself more interested in my political activities than my experiments. Thus, my science policy career aspirations were born from merging my love of science with my interest in policy and politics. After receiving my doctorate, I accepted the Henry Luce Scholarship, which allowed me to live in South Korea for 1 year and delve into the field of science policy research. This introduction into science policy occurred at the South Korean think tank called the Science and Technology Policy Institute (STEPI). During that year, I used textbooks, colleagues, and hands-on research projects as my educational introduction into the social science of science and technology decision-making. However, upon returning to the United States during one of the worst job markets in nearly 80 years, securing a position in science policy proved to be very difficult, and I was unemployed for five months. Ultimately, it took more than a year from the end of the Luce Scholarship to obtain my next science policy position with the American Society for Microbiology Congressional Fellowship. This fellowship gave me the opportunity to work as the science and public health advisor to U.S. Senator Harry Reid. While there were significant challenges during my transition from the laboratory to science policy, those challenges made me tougher, more appreciative, and more prepared to move from working at the bench to working in the field of science policy.     

我国脑科学研究战略部署及发展情况浅析

脑科学研究对于人类不断认识自身与世界有着重要意义,近年来主要发达国家纷纷制订脑科学研究规划,加大对脑科学研究的投入,力图占领这一领域的研究制高点,并推动相关产业的进步。分析了世界脑科学发展的总体态势,介绍了我国脑科学研究的总体部署和突出进展,并探讨了脑科学研究的发展前景。     

民办高校科研导师制的探索、实践与成效

大学生创新能力的培养是高等教育的重要内容之一.我院开展了基于大学生科技创新项目的科研导师制,以培养学生的创新实践能力和科研的"工匠精神",并帮助学生进行学业规划.科研导师还将项目成果转化为教学案例引入课堂,扩大受益面.科研导师制的实施得到了学生的普遍认可,人才培养质量明显提高.本文还探讨了科研导师制实施中需要关注的问题...     

Connecting the Dots between Consumer Protection,Skepticism, and Science

The concept of relevance is an obvious component in the success of classroom science investigations, but it is also one of the tenets behind the numerous media advertisements that bombard our senses on a daily basis. The authors decided to capitalize on the similarities between process-based science and the world of advertising by initiating consumer protection investigations with a side venture into the commercial world of Madison Avenue. Advertisers use many strategies in an attempt to convince consumers to buy their products. By analyzing the strategies used in a sales pitch, one begins to recognize that data can be manipulated, facts can be skewed, and visuals can be controlled to enhance product performance. Such analyses require students to look deeper and seek answers beyond the surface of presented information, superficial declarations, visual discrepancies, and verbal innuendo. In other words, such analysis is all about deciphering claims and evidence, making it analogous to science. The antithesis of this procedure, synthesizing a sales campaign for a real or imagined product, is the application of these process skills. In sum, if students can create a successful advertising campaign by using their data, then they understand the art of data manipulation and may, therefore, become better consumers.     

The global nitrogen cycle: Past, present and future

Food and energy production converts N2 to reactive N species that cascade through environmental reservoirs and in the process impact human and ecosystem health. This presentation will examine the impact of increased N mobilization on the global N cycle by contrasting N distribution in the late-19th century with those of the late-20th century. The presentation will give a general overview of regional differences and will conclude with a projection of the global N cycle for 2050.     

The impact of humans on the nitrogen cycle,with focus on temperate arable agriculture

The 6 billion people alive today consume about 25 million tonnes of protein nitrogen each year, a requirement that could well increase to 40–45 million tonnes by 2050. Most of them ultimately depend on the Haber-Bosch process to fix the atmospheric N₂ needed to grow at least part of their protein and, over the earth as a whole, this dependency is likely to increase. Humans now fix some 160 million tonnes of nitrogen per year, of which 98 are fixed industrially by the Haber-Bosch process (83 for use as agricultural fertilizer, 15 for industry), 22 during combustion and the rest is fixed during the cultivation of leguminous crops and fodders. These 160 million tonnes have markedly increased the burden of combined nitrogen entering rivers, lakes and shallow seas, as well as increasing the input of NH₃, N₂O, NO and NO₂ to the atmosphere. Nitrogen fertilizers give large economic gains in modern farming systems and under favourable conditions can be used very efficiently. Losses of nitrogen occur from all systems of agriculture, with organic manures being particularly difficult to use efficiently. Although nitrate leaching has received much attention as an economic loss, a cause of eutrophication and a health hazard, gaseous emissions may eventually prove to be the most serious environmentally. Scientists working on the use and fate of nitrogen fertilizers must be careful, clear headed and vigilant in looking for unexpected side effects.     

The global nitrogen cycle: Past, present and future

Food and energy production converts N2 to reactive N species that cascade through environmental reservoirs and in the process impact human and ecosystem health. This presentation will examine the impact of increased N mobilization on the global N cycle by contrasting N distribution in the late-19th century with those of the late-20th century. The presentation will give a general overview of regional differences and will conclude with a projection of the global N cycle for 2050.     

The design of a novel context-aware policy model to support machine-based learning and reasoning

The purpose of autonomic networking is to manage the business and technical complexity of networked components and systems. However, the lack of a common lingua franca makes it impossible to use vendor-specific network management data to ascertain the state of the network at any given time. Furthermore, the tools used to analyze management data are all different, and hence require different data in different formats. This complicates the construction of context from diverse information sources. This paper describes a new version of the DEN-ng context-aware policy model, which is part of the FOCALE autonomic network architecture. This model has been built using three guiding principles: (1) both the context model and the policy model are rooted in information models, so that they can govern managed entities, (2) each model is expressly constructed to facilitate the generation of ontologies, so that reasoning about policies constructed from the model may be done, and (3) the model is expressly constructed so that a policy language that supports machine-based reasoning and learning can be developed from it.

Sub-regional dimensions of agricultural and environmental nitrogen: The case of Asia

Asia embraces a wide range of cropping environments, largely related to the diversity of climate. To meet the high food requirements of a very large population (some 59% of the earth's total) large inputs of mineral N fertilizer are required (44.2 Tg N.yr-1 in the mid 1990s).However, because of the low (20%-50%) overall efficiency of use of fertilizer N, sometimes coupled with heavy use in intensively-farmed areas (for example in parts of China), losses of fertilizer N from agricultural land are expected to be high. Part of the N lost is thought to cause pollution of the atmosphere and water resources.A sub-regional approach, based on the FAO Agroecological Zone (AEZ) concept, has the potential to provide meaningful assessments of the agricultural and environmental dimensions of N.The AEZ concept can also provide the rationale for locating Sub-regional Centers of the International Nitrogen Initiative (INI) by basing the considerations, as far as practicable, on agroecological conditions.     

Sub-regional dimensions of agricultural and environmental nitrogen: The case of Asia

Asia embraces a wide range of cropping environments, largely related to the diversity of climate. To meet the high food requirements of a very large population (some 59% of the earth's total) large inputs of mineral N fertilizer are required (44.2 Tg N·yr-1 in the mid 1990s). However, because of the low (20%-50%) overall efficiency of use of fertilizer N, sometimes coupled with heavy use in intensively-farmed areas (for example in parts of China), losses of fertilizer N from agricultural land are expected to be high. Part of the N lost is thought to cause pollution of the atmosphere and water resources. A sub-regional approach, based on the FAO Agroecological Zone (AEZ) concept, has the potential to provide meaningful assessments of the agricultural and environmental dimensions of N. The AEZ concept can also provide the rationale for locating Sub-regional Centers of the International Nitrogen Initiative (INI) by basing the considerations, as far as practicable, on agroecological conditions.     

Philosophy of science, policy sciences and the basis of decision support with LCA Based on the toxicity controversy in Sweden and the Netherlands

Current LCA implicitly assumes that a single rational truth can be found. Mainstream policy sciences has taken a different starting point when analysing decision making in complex and controversial societal debates for already several decades. In such debates, in general, more than one reasonable conceptualisation or ‘framing’ of the problem is at stake which forms the core of the controversy. This paper analyses the Dutch chlorine debate and the Swedish PVC debate and shows that (three) frames also play a role in toxicity controversies: the risk assessment frame, the strict control frame, and the precautionary frame. The latter frame, adhered to by the environmentalists, seeks to judge substances mainly on their inherent safety. The cases show that this logic may be defended as at least being equally reasonable to the emission-effect calculations that form the core of Risk Assessment and Life-cycle Impact Assessment (LCIA). As predicted by policy sciences, this finding implies that the political neutrality of tools like LCIA is questionable. In summary, the approaches and procedures developed for LCA have to be reconciled with key lessons from policy science and philosophy of science, i.e. considering the fact that multiple realities play a key role in many decision making processes. This paper suggests some alternative indicators for toxicity evaluations, and indicates the implications of LCA method development.     

Indicators for nitrogen status and leaching in subtropical forest ecosystems,South China

The deposition of nitrogen (N) is high in subtropical forest in South China and it is expected to increase further in the coming decades. To assess effects of increasing deposition on N cycling, we investigated the current N status of two selected 40–45-year-old masson pine-dominated Chinese subtropical forest stands at Tieshanping (TSP, near Chongqing City) and Caijiatang (CJT in Shaoshan, Hunan province), and explored the applicability of several indicators for N status and leaching, suggested for temperate and boreal forest ecosystems. Current atmospheric N deposition to the systems is from 25 to 49 kg ha⁻¹ year⁻¹. The concentration of total N in the upper 15 cm of the soil is from as low as 0.05% in the B₂ horizon to as high as 0.53% in the O/A horizon. The concentration of organic carbon (C) varies from 0.74 (B₂) to 9.54% (O/A). Pools of N in the upper 15 cm of the soils range from 1460 to 2290 kg N ha⁻¹, where 25–55% of the N pool is in the O/A horizon (upper 3 cm of the soil). Due to a lack of a well-developed continuous O horizon (forest floor), the C/N ratio of this layer cannot be used as an indicator for the N status, as is commonly done in temperate and boreal forests. The net N mineralization rate (mg N g⁻¹ C year⁻¹) in individual horizons correlates significantly with the C/N ratio, which is from as high as 18.2 in the O/A horizon to as low as 11.2 in the B₂ horizon. The N₂O emission flux from soil is significantly correlated with the KCl extractable NH₄⁺–N in the O/A horizon and with the net nitrification in the upper 15 cm of the soil. However, the spatial and temporal variation of the N₂O emission rate is high and rates are small and often difficult to detect in the field. The soil flux density of mineral N, defined as the sum of the throughfall N input rate and the rate of in situ net N mineralization in the upper 15 cm of the soil, i.e., the combination of deposition input and the N status of the system, explains the NO₃⁻ leaching potential at 30 cm soil depth best. The seasonality of stream water N concentration at TSP and CJT is climatic and hydrologically controlled, with highest values commonly occurring in the wet growing season and lowest in the dry dormant season. This is different from temperate forest ecosystems, where N saturation is indicated by elevated NO₃⁻ leaching in stream water during summer.     

The marine nitrogen cycle: recent discoveries,uncertainties and the potential relevance of climate change

The ocean''s nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation, assimilation, nitrification, anammox and denitrification. Dinitrogen is the most abundant form of nitrogen in sea water but only accessible by nitrogen-fixing microbes. Denitrification and nitrification are both regulated by oxygen concentrations and potentially produce nitrous oxide (N₂O), a climate-relevant atmospheric trace gas. The world''s oceans, including the coastal areas and upwelling areas, contribute about 30 per cent to the atmospheric N₂O budget and are, therefore, a major source of this gas to the atmosphere. Human activities now add more nitrogen to the environment than is naturally fixed. More than half of the nitrogen reaches the coastal ocean via river input and atmospheric deposition, of which the latter affects even remote oceanic regions. A nitrogen budget for the coastal and open ocean, where inputs and outputs match rather well, is presented. Furthermore, predicted climate change will impact the expansion of the oceans'' oxygen minimum zones, the productivity of surface waters and presumably other microbial processes, with unpredictable consequences for the cycling of nitrogen. Nitrogen cycling is closely intertwined with that of carbon, phosphorous and other biologically important elements via biological stoichiometric requirements. This linkage implies that human alterations of nitrogen cycling are likely to have major consequences for other biogeochemical processes and ecosystem functions and services.     

Evaluation of three different types of nitrogen,heavy metals,and endocrine disruptors in water and sediments of Wenyu River

Concentrations of NO₃^?(nitrate), NO₂^?(nitrite), NH₄⁺(ammonia nitrogen), Mn, Fe, Ba, As, Se, Cd, Pb, Cr⁶⁺, estrone (E1), estradiol (E2), ethinylestradiol (EE2), estriol (E3), bisphenol A (BPA), nonylphenol (NP) and 4-tert-octylphenol (OP) had been estimated in water and sediments of Wenyu River. Using single factor, ecological risk assessment, geoaccumulation index, human health risk assessment and multivariate statistical analysis, we described the current situation of river contamination, human health risks of different age groups and possible sources of pollutants as well as their transformation characteristics. The results showed that main contaminants were NH₄⁺, NO₃^?, NO₂^?, EE2 and E3, E1 in water, while sediments have been slightly polluted by heavy metals, whose order of polluting degree is Zn>Cr⁶⁺>Cd>Cu. Residents in the study area are exposed to the risk, and EE2 made the greatest contribution to it. E1, As, and NO_3^- also affect negatively on the health of the residents, and NO_2^- only do harm to juveniles. Human activities and industrial production are main sources of contaminants, also they can transform into each other between water and sediments. Heavy metal ions can be easily precipitated by Ferric oxide or hydroxide, E2 and EE2 are also transformed into E3 in natural environment.     

长期灌溉施肥对半干旱区褐土氮、磷和钾库的影响

采用二次回归通用旋转组合设计 ,在辽西半干旱区进行了长期田间试验 ,研究灌水、施氮、施磷和施秸秆对土壤氮素含量的影响。结果表明 ,灌水在促进作物生长和提高产量的同时 ,使得土壤中的全氮和水解氮含量有所降低 ,施氮肥能够提高土壤中的氮素含量 ,土壤氮素含量随着磷肥施用量的增加先降低后增加 ,施秸秆能显著提高土壤氮素含量特别是水解氮含量。因此 ,秸秆施用是保持和提高土壤氮素营养的有效措施。     

植物的光合作用与光合氮、碳代谢的耦联及调节

概述了光合作用反应与CO2同化和NO^-3/NO^-2还原的耦联关系,提出了应该从氮,碳代谢整合角度讨论作动和光合作用,以便根据生产目的,调节作物的氮,碳代谢,实现农业生产的高产,优质。