煤矿区规划环评中的大气环境影响预测方法探讨

根据煤矿区规划环评的现状,提出了几种煤矿区规划环评中的大气环境影响预测方法,并将多源叠加的高斯模型法和箱模式法分别应用于榆神矿区和神东矿区的大气环境影响预测中.结果表明,多源叠加的高斯模型法灵活多变,而箱模式简单易行.     

危岩体断裂特性的网格重构数值仿真研究

危岩体稳定是三峡库区的主要关注点之一.为探究不同裂纹赋存形态以及不同降雨工况下危岩体断裂的变形特性,基于围道积分原理,在Abaqus平台上利用Python语言开发了基于断裂力学理论的危岩体任意裂纹扩展的网格重构数值模拟方法,该方法与以往危岩体裂纹扩展数值模拟方法相比,能够体现危岩体裂纹尖端的断裂力学特征,实现连续介质中...     

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the RO_x (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%–150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%–50% enhancements in the areas around 35–40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.     

重金属污染土壤修复技术现状与展望

目前重金属污染土壤修复主要采用物理化学技术和植物修复技术。根据其作用过程和机理,物理化学技术主要包括化学固化、土壤淋洗和动电修复;植物修复技术包括植物稳定、植物挥发和植物提取。本文就修复技术的原理、优缺点、实用性及研究现状与发展动态等方面进行了综述与分析。     

Simulation of three-stage operating temperature for supersaturation water-based condensational growth tube

In order to realize accurate dynamic control of supersaturation and to study condensation growth characteristics of nanoparticles through different levels of super saturation,a series of parametric analyses and systematic comparisons between two-stage and three-stage operating temperature designs were simulated with COMSOL Multiphysics.The simulation results showed that the three-stage operating temperature did not change peak supersaturation compared with two operating temperatures,and the three-stage operating temperature was superior in decreasing the amount of water vapor and the temperature,thus lowering particle loss and variation in detection and collection.The peak supersaturation level increased by 0.3 as the flow rate increased from 0.6 to 2.0 L/min,but the supersaturation peak moved from 0.0027 z0 to 0.08 z0(i.e.,the growth time and the final size decreased by 40%).Peak supersaturation increased as the temperature difference increased or the temperature difference window was shifting left,and minimum activation size decreased.Shifting the 70℃temperature difference window from 9℃,79℃-1℃,71℃for the condenser and initiator temperatures resulted in peak supersaturation in the centerline being above 5.8,and the activation size changed as low as 1 nm.Experiments with flow rates varying by a factor of 2.5(from 0.6 to 1.5 L/min) resulted in a final size decrease of 43%(from 3.2 to 1.8 μm),and experimental results of outlet particle size distributions were equivalent with theoretical analysis as the operating temperature was changed.     

基于生态管理的流域水环境功能区划——以浑河流域为例

从环境战略管理的高度,提出了一种基于生态管理的流域水环境功能区划分方法.在现行水环境功能区划的基础上,结合生态管理理念及相关理论,并充分考虑我国水环境管理能力及发展趋势,进行流域水环境功能区划分.流域水环境功能区划以流域水生态分区为基础,根据参考条件评估水体的生态状况,考虑水体生态保护功能和最小生态需水量,提出新的流域水环境功能区划的理论基础和技术方法体系.首次将水生态分区、水生态保护目标和生态需水量引入水环境功能区划之中,对原水环境功能区划的内涵进行了拓展.该方法以浑河流域为案例做了实证研究.     

跨介质航行器高速斜入水跳弹现象研究

目的 揭示跨介质航行器高速入水跳弹行为的机理,提高航行器的突防能力。方法 基于STAR-CCM+流体仿真软件,采用VOF多相流模型以及Schnerr-Sauer空化模型,计算航行器跳弹过程的空化流场,并运用重叠网格技术,耦合六自由度弹道方程,求解航行器的运动特性。利用所建立的计算模型,研究航行器在不同入水速度和角度下的空泡演化、水动力和弹道特性,揭示航行器产生跳弹现象的原因和规律。结果 航行器在小角度高速入水时,水下运动轨迹会发生很大的变化,经历了入水、浸水、出水3个阶段。结论 产生跳弹现象的主要原因是航行器在入水后,头部上下缘以及弹尾两侧受力不均,形成了向上的偏转力矩,使得航行器的俯仰角发生了较大的改变,并且随着航行器的入水速度加快,入水角度减小,跳弹现象越容易产生。     

Sentiment analysis as a measure of conservation culture in scientific literature

Culturomics is emerging as an important field within science, as a way to measure attitudes and beliefs and their dynamics across time and space via quantitative analysis of digitized data from literature, news, film, social media, and more. Sentiment analysis is a culturomics tool that, within the last decade, has provided a means to quantify the polarity of attitudes expressed within various media. Conservation science is a crisis discipline; therefore, accurate and effective communication are paramount. We investigated how conservation scientists communicate their findings through scientific journal articles. We analyzed 15,001 abstracts from articles published from 1998 to 2017 in 6 conservation-focused journals selected based on indexing in scientific databases. Articles were categorized by year, focal taxa, and the conservation status of the focal species. We calculated mean sentiment score for each abstract (mean adjusted z score) based on 4 lexicons (Jockers-Rinker, National Research Council, Bing, and AFINN). We found a significant positive annual trend in the sentiment scores of articles. We also observed a significant trend toward increasing negativity along the spectrum of conservation status categories (i.e., from least concern to extinct). There were some clear differences in the sentiments with which research on different taxa was reported, however. For example, abstracts mentioning lobe finned fishes tended to have high sentiment scores, which could be related to the rediscovery of the coelacanth driving a positive narrative. Contrastingly, abstracts mentioning elasmobranchs had low scores, possibly reflecting the negative sentiment score associated with the word shark. Sentiment analysis has applications in science, especially as it pertains to conservation psychology, and we suggest a new science-based lexicon be developed specifically for the field of conservation.     

三峡库区澎溪河底泥及消落区土壤磷的形态及吸附特性研究

沉积物是自然水域的重要生态组成部分,是形成湖泊、水库富营养化的关键因素之一.为研究三峡库区澎溪河流域沉积物中磷的赋存形态特征及迁移转化规律,采用连续提取法对澎溪河底泥3个断面及消落区3种土壤类型中磷赋存形态进行分析,并通过等温吸附实验研究了磷的吸附规律,确定了零净吸附磷浓度(EPC0).结果表明,澎溪河底泥中的总磷含量在0.80～1.45 g·kg-1之间,赋存形态以无机磷为主,其中钙结合磷和蓄闭态磷比例在80%以上,铁铝结合磷含量较低,该流域底泥受自然岩石状态及沉积环境的影响较大,而人为活动对其影响较小;消落区土壤总磷含量在0.65～1.16 g·kg-1之间,磷的赋存形态也以无机磷为主,冲积土和紫色土也以钙结合态磷和蓄闭态磷为主,水稻土中则以蓄闭态磷含量最高.澎溪河高阳、黄石和双江3个断面底泥的EPC0分别为0.08、0.13和0.11 mg·L-1,消落区冲积土、紫色土和水稻土的EPC0分别为0.08、0.09和0.04 mg·L-1.EPC0值与沉积物中总磷、pH、Ca-P、黏粒含量呈正相关性,其中与pH和Ca-P相关性显著.根据澎溪河上覆水中磷浓度的季节变化,初步判定底泥及消落区土壤在夏秋季节为磷的"汇",在冬春季节则成为其"源".EPC0高于水体富营养化临界值,底泥及消落区土壤中磷的释放依然是不可忽视的潜在问题.     

Limiting the impact of light pollution on human health, environment and stellar visibility

Light pollution is one of the most rapidly increasing types of environmental degradation. Its levels have been growing exponentially over the natural nocturnal lighting levels provided by starlight and moonlight. To limit this pollution several effective practices have been defined: the use of shielding on lighting fixture to prevent direct upward light, particularly at low angles above the horizon; no over lighting, i.e. avoid using higher lighting levels than strictly needed for the task, constraining illumination to the area where it is needed and the time it will be used. Nevertheless, even after the best control of the light distribution is reached and when the proper quantity of light is used, some upward light emission remains, due to reflections from the lit surfaces and atmospheric scatter. The environmental impact of this "residual light pollution", cannot be neglected and should be limited too. Here we propose a new way to limit the effects of this residual light pollution on wildlife, human health and stellar visibility. We performed analysis of the spectra of common types of lamps for external use, including the new LEDs. We evaluated their emissions relative to the spectral response functions of human eye photoreceptors, in the photopic, scotopic and the 'meltopic' melatonin suppressing bands. We found that the amount of pollution is strongly dependent on the spectral characteristics of the lamps, with the more environmentally friendly lamps being low pressure sodium, followed by high pressure sodium. Most polluting are the lamps with a strong blue emission, like Metal Halide and white LEDs. Migration from the now widely used sodium lamps to white lamps (MH and LEDs) would produce an increase of pollution in the scotopic and melatonin suppression bands of more than five times the present levels, supposing the same photopic installed flux. This increase will exacerbate known and possible unknown effects of light pollution on human health, environment and on visual perception of the Universe by humans. We present quantitative criteria to evaluate the lamps based on their spectral emissions and we suggest regulatory limits for future lighting.