河南省畜禽粪便污染及耕地负荷时空变化特征分析

为了解河南省畜禽养殖废弃物对环境污染的影响,根据河南省2006年～ 2012年统计数据,以各地级市为单位,分析了2006年～ 2012年河南省主要畜禽粪便产生总量及养分总量、单位耕地面积粪便负荷量及其污染风险预警.结果表明：河南省畜禽粪便产生总量约为28627万吨,猪粪和牛粪占粪便总量的84.5％以上,畜禽粪便还田后,粪便中的养分含量将对该省的水环境造成污染;河南省耕地畜禽粪便负荷预警级别在I级与Ⅳ级之间,风险较高的地市主要集中在漯河、鹤壁等市,尤其是鹤壁市,负荷量最高达59t/hm2.因此,这些地级市应该加强畜禽粪便的风险管理和综合治理工作.     

Accounting for the effect of concentration fluctuations on toxic load for gaseous releases of carbon dioxide

In Great Britain, advice on land-use planning decisions in the vicinity of major hazard sites and pipelines is provided to Local Planning Authorities by the Health and Safety Executive (HSE), based on quantified risk assessments of the risks to the public in the event of an accidental release. For potential exposures to toxic substances, the hazard and risk is estimated by HSE on the basis of a “toxic load”. For carbon dioxide (CO₂), this is calculated from the time-integral of the gas concentration to the power eight. As a consequence of this highly non-linear dependence of the toxic load on the concentration, turbulent concentration fluctuations that occur naturally in jets or plumes of CO₂ may have a significant effect on the calculated hazard ranges. Most dispersion models used for QRA only provide estimates of the time- or ensemble-averaged concentrations. If only mean concentrations are used to calculate the toxic load, and the effects of concentration fluctuations are ignored, there is a danger that toxic loads and hence hazard ranges will be significantly under-estimated.This paper explores a simple and pragmatic modification to the calculation procedure for CO₂ toxic load calculations. It involves the assumption that the concentration fluctuates by a factor of two with a prescribed square-wave variation over time. To assess the validity of this methodology, two simple characteristic flows are analysed: the free jet and the dense plume (or gravity current). In the former case, an empirical model is used to show that the factor-of-two approach provides conservative estimates of the hazard range. In the latter case, a survey of the literature indicates that there is at present insufficient information to come to any definite conclusions.Recommendations are provided for future work to investigate the concentration fluctuation behaviour in dense CO₂ plumes. This includes further analysis of existing dense gas dispersion data, measurements of concentration fluctuations in ongoing large-scale CO₂ release experiments, and numerical simulations.     

救生舱高温环境的传热研究

为提高救生舱热防护能力,延长救援时间,在空载状态下救生舱热载荷研究的基础上,提出救援状态下救生舱外部传热热负荷的量化方法。已知救援状态下救生舱内、外温度随时间变化曲线,拟合温度函数。依据温度变化特点划分区间,积分求取各区间上温度平均值,计算温差,由传热方程计算救援状态下救生舱的热载荷。以某型号救生舱载人综合防护试验为例,根据模拟灾变环境的温度变化特点,运用该方法计算最高温度与常态温度下外部高温空气向舱体及其内部空间传热的热载荷,得到救生舱的总热负荷,外部传热最大传热功率及救生舱热载荷负荷范围。     

高含硫化氢井场公众疏散能力分析方法研究

我国含硫气田存在含硫量高、周边人口稠密、地形复杂等危险因素,如何保证含硫气田周边居民安全疏散成为一个重要的急需解决的问题.针对高含硫气田开发过程面临的公众疏散能力问题,采用毒性负荷判别法作为疏散能力评估的准则,提出一套分析流程,并给出相应的改进措施,形成一整套的复杂地形下高含硫化氢井场公众安全疏散能力分析方法;通过对本方法在现场实际中的应用,在理论和实例分析基础上,发现对高含硫气田井场进行疏散能力评估是可行且非常必要的.     

应用动态模型确定酸沉降临界负荷的探讨

任何一个天然生态系统都是一个稳定系统.在一定酸沉降量的作用下,生态系统最终会平衡在一个新的稳定状态.动态模型可以模拟不同酸沉降量下生态系统化学状态的变化趋势.根据信号与系统理论,这种趋势可以用一阶指数衰减函数进行模拟,以得到系统达到稳定状态时的化学指标值.根据不同酸沉降量和所对应的稳态化学指标值之间的剂量-响应曲线,可以求出当系统稳态化学指标值达到临界化学值时的酸沉降量,即为系统的酸沉降临界负荷.应用这种方法,以MAGIC模型为例,计算了四川峨眉山顶水和重庆南山湖泊的硫沉降临界负荷,分别为1.54和6.5     

Numerical simulation of far-field blast loads arising from large TNT equivalent explosives

Large TNT equivalent explosions usually arise from accidents occurring during the transportation, storage, and manufacturing of chemicals relevant to process industries. The blast wave generated by the explosion will spread and interact with the surrounding factories and storehouses, damaging the building structures within several kilometers and causing significant casualties and property losses. This study aims to develop an efficient numerical simulation method to predict blast loads to estimate the consequences of accidents involving far-field free air bursts or surface burst explosions. Before its interaction with the interested target, a blast wave is generated in the numerical model by specifying the initial and boundary conditions of the disturbed air. Based on empirical data of incident overpressure, an explicit formula to calculate the air particle velocity is derived from the governing equations of a perfect inviscid gas. A simplified path line method is proposed to calculate the air density. The proposed method is applied to the LS-DYNA CESE solver to simulate the blast loads on building structures in the far field. Validations against empirical data and experiments indicate that the proposed method is sufficiently accurate for engineering applications and, through a case study, presents a more efficient performance than the LOAD_BLAST_ENHANCED (LBE) and mapping methods.     

移动式环保公厕车防震抗风安全性研究

移动式环保公厕车工作地点范围广、环境复杂,且没有地基固定,要求其具有特别高的抗地震能力、抗风载变形能力。利用有限元仿真的方法,研究了移动式环保公厕车在不同地震载荷、风力载荷条件下的变形和应力状况,分析了地震载荷和风力载荷对移动式环保公厕车破坏程度和破坏机理,对比了单一载荷作用与复合载荷作用的区别,从而为移动式环保公厕车使用环境的选择、安全检查的合理安排等提供有力的参考依据。     

The role of agri‐environment schemes in conservation and environmental management

Over half of the European landscape is under agricultural management and has been for millennia. Many species and ecosystems of conservation concern in Europe depend on agricultural management and are showing ongoing declines. Agri‐environment schemes (AES) are designed partly to address this. They are a major source of nature conservation funding within the European Union (EU) and the highest conservation expenditure in Europe. We reviewed the structure of current AES across Europe. Since a 2003 review questioned the overall effectiveness of AES for biodiversity, there has been a plethora of case studies and meta‐analyses examining their effectiveness. Most syntheses demonstrate general increases in farmland biodiversity in response to AES, with the size of the effect depending on the structure and management of the surrounding landscape. This is important in the light of successive EU enlargement and ongoing reforms of AES. We examined the change in effect size over time by merging the data sets of 3 recent meta‐analyses and found that schemes implemented after revision of the EU's agri‐environmental programs in 2007 were not more effective than schemes implemented before revision. Furthermore, schemes aimed at areas out of production (such as field margins and hedgerows) are more effective at enhancing species richness than those aimed at productive areas (such as arable crops or grasslands). Outstanding research questions include whether AES enhance ecosystem services, whether they are more effective in agriculturally marginal areas than in intensively farmed areas, whether they are more or less cost‐effective for farmland biodiversity than protected areas, and how much their effectiveness is influenced by farmer training and advice? The general lesson from the European experience is that AES can be effective for conserving wildlife on farmland, but they are expensive and need to be carefully designed and targeted.     

中国农田N_2O排放量的估算

排放量估算是温室效应气体研究的重要内容。本文论述了影响农田Ｎ２Ｏ排放量估算准确性的因素，讨论如何提高农田Ｎ２Ｏ排放量估算的准确性，并估算了中国农田Ｎ２Ｏ排放总量。     

湿地冷湿效应初探

对湿地周围不同距离农田的近地面气温、湿度、地温以及典型湿地地温的测定表明 ,湿地冷湿效应与湿地植被及其积水深度有关。在所选择的 3种湿地植被中 ,漂筏苔草积水最深 ,冷湿效应最大 ,其次为毛果苔草 ,小叶章最小。不同距离农田的近地面气温和湿度变化不同 ,随距离增加 ,温度增大 ,湿度减小。这种变化主要是由湿地的局部冷湿作用造成的。农田地温平均值高出小叶章湿地 4℃之多 ,高出漂筏苔草湿地近 5℃ ,表明湿地的制冷作用很明显