河北海域荧光法测定叶绿素含量周年季节分层分布

2006～2007年春夏秋冬在河北海域进行了四个航次分层叶绿素a调查,结果表明:春季(4月),全海域表层叶绿素a平均值为0.65 mg/m~3(0.12～2.69 mg/m~3),中层为1.02 mg/m~3(0.08～3.47 mg/m~3),底层为1.03 mg/m~3(0.12～5.05 mg/m~3);夏季(7月),全海域表层叶绿素a平均值为3.45 mg/m~3(0.63～11.28 mg/m~3),中层为3.40 mg/m~3(0.88～11.50 mg/m~3),底层为3.37 mg/m~3(1.00～11.39 mg/m~3);秋季(10月),全海域表层叶绿素a平均值为5.83 mg/m~3(1.80～13.50 mg/m~3),中层为4.54± 3.33 mg/m~3(1.60～12.80 mg/m~3),底层为5.40 mg/m~3 (2.50～12.70 mg/m~3);冬季(11月),全海域表层叶绿素a平均值为1.21 mg/m~3 (0.47～7.79 mg/m~3),中层为0.79 mg/m~3 (0.47～1.41 mg/m~3),底层为0.86 mg/m~3(0.39～1.93 mg/m~3).总体趋势是春季唐山外部海域叶绿素a浓度较高,夏季秦皇岛和黄骅近岸海域叶绿素a浓度较高,秋季秦皇岛近岸海域叶绿素a浓度较高,冬季唐山近岸海域叶绿素a浓度较高.     

水涤脱附条件下活性炭脱硫中有效吸附位的研究

以不同活性炭材料吸附性能测试实验的结果为依据,研究了在水涤脱附条件下活性炭脱硫的机理,指出水在吸附位部分失效过程中起到的几种作用,并从有效吸附位的角度进一步分析了吸附材料特性与吸附性能之间的关系,提出产生有效吸附位的前提是具有一定的反应空间,使之能满足反应分子间距和空间构型的条件.研究表明:吸附材料的孔径分布和外表面积是影响吸附性能的两个关键因素;平均孔径40～50A、颗粒直径为3 mm左右的中孔型颗粒活性炭,是一种理想的吸附材料.     

虚拟现实地理信息系统技术在城市环境污染突发事件中应用探讨

通过分析事件驱动原理,将事件驱动机制（EDI）融入虚拟现实地理信息系统（VRGIS）的建模框架,探索基于VRGIS的事件驱动时空模型及其在城市环境污染突发事件响应中的应用前景以及主要技术设计过程,旨在为资源与环境的可持续利用研究提供一个形象直观的虚拟演示平台来反映城市中环境变化的空间响应及其对策定制等问题。     

Positive long-term effect of mulching on species and functional trait diversity in a nutrient-poor mountain meadow in Central Europe

Oligotrophic mountain meadows are threatened biodiversity hotspots throughout Europe. The traditional summer hay-making followed by autumn grazing is no longer economic and question is whether alternative managements can maintain both plant species and functional diversity typical of these habitats. In the Bohemian Forest Mts., we applied three treatments (mowing once a year - i.e., cutting and removing the biomass, mulching once a year - cutting and leaving the crushed biomass to decompose in situ, fallowing - no cutting) in order to assess temporal changes in meadow vegetation, plant trait composition and biomass production in a 13-year experiment. We recorded for each species twenty-five traits as to be most informative of plant strategies related to growth, resource acquisition and carbon-water economy. We compared different components of trait composition (community averages that mostly reflect traits of dominant species vs. the Rao index of functional diversity that reflects trait dissimilarity among species) and their impact on biomass production. We show that mulching promotes species and functional diversity by facilitating heliophilous forbs and legumes with more acquisitive strategies in resource use and release, e.g., higher foliar N and P content. This occurs at the expense of tall grasses (with resource-retentive strategies, e.g., high leaf dry matter content) which dominate the mown and fallow plots. The divergence in most quantitative traits indicates that niche complementarity is the dominant assembly process in mulched plots, which can prevent competitive exclusion and enable species coexistence. The divergent development was detected only after 5-6 years. This slow floristic and functional response is caused by acidity of soil and severe mountain climate that preclude rapid responses of vegetation to land-use changes. We conclude that mulching represents a good compromise maintaining both plant species and functional diversity as well as a relatively high biomass production. Mowing without grazing leads to gradual nutrient loss and thus reduces the productivity and diversity in these oligotrophic ecosystems. Fallowing causes gradual loss in diversity by increased grass competition and litter accumulation.     

污染物总量控制空间动态管理初探

基于不同区域的环境要求,可将一个地区污染物总量控制分为禁止开发区、限制开发区和普通区.本文建立了普通区污染物总量控制目标值及变化值的计算方法,并将此方法具体应用到某市的污染物空间总量动态控制管理研究中.通过选取最佳分配方案,从而达到"经济发展最好、环境质量最优"的效果.     

喀斯特地区城市绿地土壤呼吸对降水变化的响应研究

降水是影响土壤呼吸一个重要的影响因子,研究降水对土壤呼吸的影响,对估计和预测陆地生态系统土壤呼吸变化有着重要的意义,但目前自然降水对喀斯特地区城市绿地土壤呼吸影响的研究目前还鲜有报道.本研究利用静态暗箱法,对降水后贵阳城市绿地土壤呼吸速率变化进行了24 h定位监测,对比研究了不同强度降水后土壤呼吸速率变化,并分析了水热...     

Experimental and numerical study of CO2 plume diffusion in a confined space

In this paper, heavy gas diffusion in a confined space has been investigated. The effects of barrier and source intensity on CO₂ diffusion are explored by the small-scale experiments and computational fluid dynamics (CFD) methods. Six different turbulence models are selected to predict the gas concentrations. By comparing these experimental values with the simulated ones, it is found that all models can effectively predict the concentration variation with time, and SST k-ω model is most close to the ideal model compared with others. Three source-barrier distances and three CO₂ flow rates have been set up for the study. In this confined space, the main flow is concentrated in the region near the ground. The existence of barriers in the space will have a dilution effect on the high-concentration plume near the ground of the near-source area and a barrier effect on the low-concentration plume in the far-source area. The changes in source intensity have notable impact on the gas concentrations. This study can provide an experimental basis for the risk assessment in the confined spaces, as well as an experimental and data reference for large-scale CFD simulations.     

Numerical investigation and analysis of indoor gas explosion: A case study of “6·13” major gas explosion accident in Hubei Province,China

Taking the ' 6·13 ′ major gas explosion accident in Shiyan, Hubei Province, China as an example, three problems were studied in this work: (1)The determination of the volume of natural gas involved in the explosion; (2)The propagation process of shock wave inside the building and the damage evolution process of the accident-related building; (3)The overpressure and fragment injury to the person outside the building. Through the numerical simulation in ANSYS/LS-DYNA software, the volume of natural gas involved in the explosion is determined to be 10240 × 1400 × 400 cm (length × width × height) from three perspectives: the damage to the building, the distribution of overpressure inside the building, and the TNT equivalent of the explosion energy. The simulation results are in good line with the accident, which verifies the effectiveness of the scheme and the accuracy of the numerical model. Based on the reasonable filling scheme, the propagation process of shock waves inside the building, the damage evolution process of the building, and the injury ranges of overpressure and fragments outside the building are analyzed. It can be found that the propagation of shock waves in confined space is complex and variable. The explosion shock waves are first reflected and superimposed in the watercourse, resulting in pressure rise. At about 8ms, the shock waves rushed into the first-floor space of the building, and the maximum overpressure was about 0.56 MPa. At about 50 ms, the shock waves rushed into the second-floor space, and the maximum overpressure was about 0.139 MPa. The first and second-floor slabs and infilled walls were almost completely destroyed. The interior walls of the infilled walls are mainly collapsed, and the exterior walls are ejection around the building as the center. The peak displacement and peak velocity of the interior walls of each floor are about 15% of the exterior walls. The fragments which cause fragment injury mainly come from the retaining wall above the watercourse, the maximum velocity is about 89 m/s, and the maximum displacement is 8.9 m. The safety distance of fragment injury is about 8.8 m, while the safety distance of overpressure injury is about 4.6 m. The lethal distance of fragment injury is greater than that of overpressure injury. Compared with the distance between different damage levels of overpressure injury, the difference in fragment injury is small. Therefore, the safety assessment at the engineering level only needs to consider the safety distance of fragment injury. This study can provide suggestions for evaluating the damage of natural gas cloud explosions in confined spaces and is helpful for accident investigation and safety protection.     

受限空间作业的风险分析与控制

受限空间作业涉及的行业多、危险因素多,发生事故时救援难度大且后果严重。本文在对受限空间作业风险进行分析的基础上,从安全管理、作业过程、作业环境三个方面提出了相应的风险控制措施和建议。该研究对有效控制受限空间作业的风险以及预防事故的发生具有重要的意义。     

临近空间环境及环境试验

从热力学结构、大气成分特征、大气电磁特性等方面介绍了临近空间环境参数,按照临近空间飞行器的平均密度、飞行速度、飞行高度介绍了临近空间飞行器的分类及特点。阐述了临近空间环境试验的方法,并对临近空间环境试验技术的发展提出了初步建议。