公路交通对土壤铅污染预测评价

推导给出了公路交通对土壤铅污染的预测计算模式，分析了采用该模式预测土壤中铅含量时可能出现的3种不同结果，即高于、等于或低于背景值及其判别条件。结合中国公路交通的实际情况，论证了在不考虑非公路污染源时，公路交通引起土壤中铅累积量在营运近期将低于土壤背景值。认为合理确定非公路污染源强度、铅沉降面积及铅残留系数是影响预测评价土壤铅污染的主要因素。     

难降解有机污染物共降解机理解析

应用构建于关键酶的细胞２个层次的共降解数学模型，对高生物量和低生物量２种情况下难降解有机物（三氯乙烯）的共降解进行了模拟分析。结果表明，第一营养基质的诱导作用决定着共降解微生物细胞内关键酶的浓度，但是，由于竞争关系，过高的营养基质浓度反而导致共降争速率的下降，适当投加能量基质能够提高共降解过程速率，但是过量投加能量基质可能不利于长期维持微生物的活性。在共降解过程中，微生物能够通过自我恢复作用，对抗     

人工神经网络在环境科学中的应用研究

以B-P网络为例介绍了人工神经网络模型的应用原理。以开拓人工神经网络在环境科学中的应用范围为目的,综述了几种常用神经网络模型在环境预测与评价2方面的应用性能。结果表明:人与环境关系的科学量度是多方位、多因素的非线性模糊问题,而人工神经网络模型具有解决该类问题的独特优点。针对不同环境问题,优选模型,开拓人工神经网络方法在环境科学中的应用范围,为环境问题的解决提供新的技术手段。     

南岳森林群落生物多样性研究(Ⅲ)广济寺森林群落植物物种相对多度分布格局

本文选用几何级数分布、分割线段、对数级数分布和对数正态分布等模型研究了南岳广济寺森林群落植物物种相对多度的分布格局。结果表明,对数级分布模型适于拟合南岳广济寺森林群落乔木层和灌木层物种相对多度的分布格局;分割线段中的序列一多度模型仅适合于乔木层;对数正态分布模型仅适合于草本层;几何级数分布模型完全适合于拟合任何层次。此外,α指数值亦显示出本群落接近山地季雨林的多样性水平。     

Trail following in ants: individual properties determine population behaviour

This paper deals with the purposeful marking of trails as a mechanism for coordinating movement. Patterns of motion are adapted to the environmental conditions, the functions to be carried out, and the condition of the organism; therefore, the networks of trails must change both quantitatively and qualitatively over time. The nature of such changes, and how they are controlled at the individual level are discussed. In particular, we show that slight modulations in individual traits, in the trail marker, or in the size of the group can account for major changes in movement patterns at the population level such as abrupt transitions from diffuse area-covering networks to focused trunk trails. Using a mathematical model and computer (cellular automata) simulation we show that trunk trails carrying a high density of traffic can form spontaneously under suitable conditions from an initially randomly distributed group. The key to this self-organizing property stems from interactions between individuals that lead to a collective effect in recruitment to trails: the influence of small groups of individuals increases rapidly with group size. The dichotomy between high traffic (strong) trunk trails versus diffuse (weak) networks is discussed.     

Experimental verification for real-time environmental emergency response system: WSPEEDI by European tracer experiment

Japan Atomic Energy Research Institute has developed an emergency response system WSPEEDI to forecast long-range atmospheric dispersions of radionuclides discharged into the atmosphere. The latest version of WSPEEDI consists of an atmospheric dynamic model MM5 for calculating meteorological fields and a particle random-walk model for atmospheric dispersion. The performance of WSPEEDI was evaluated by data obtained from a field tracer experiment over Europe (ETEX) in this paper. The model validation was done with respect to the following points: (1) the dependence of model accuracy on the temporal and spatial resolutions of the meteorological fields and (2) the superiority of an atmospheric dynamic model over a mass-consistent wind model. Regarding (1), it was shown that the calculation accuracy of the new version with high temporal resolution was improved, especially at the edge of the plume. Moreover, although the increase in horizontal spatial resolution of the old version had no substantial effect on the model performance, increase in horizontal resolution of the new version contributed to the significant improvement of the calculation accuracy. These results showed that the dynamically calculated meteorological field with the spatial resolution of the meso-β–γ scale greatly improved calculation accuracy.     

Shifted power-law relationship between NO2 concentration and the distance from a highway: A new dispersion model based on the wind profile model

In this paper, a shifted power-law model, based on the wind profile model, had been supposed to simulate concentration gradient of nitrogen dioxide (NO₂) with distance from a highway. Field experiments were performed for NO₂ gradients from a highway in Shanghai by using passive samplers. The shifted power-law model was fitted well with experimental results of field experiments both in this study and in the literature. The results not only verified the validity of shifted power-law relationship between NO₂ concentration and the distance from a highway, but also partially demonstrated that there were some significant similarities between wind profile and air pollutants concentration profile near highway. With known concentration of chosen reference point and appropriate value of the parameter k, the model could be practically applied for predicting the NO₂ distributions near a highway. The methods of determining the parameter k were also discussed for further detailed studies.     

冶金企业无组织排放颗粒物影响评价

以上海市某冶金企业为例,该厂有正常运行的冶炼炉13座,每年向大气中排放大量颗粒污染物.基于高斯倾斜烟羽模式,整理了2003年上海市全年的气象资料,运用气象概率矩阵法计算了该厂直排点源及无组织面源排放颗粒物的影响,得出了厂区内无组织排放颗粒物落地浓度等值线图.计算结果表明,厂区内颗粒物污染主要来自无组织面源,污染集中在厂区中心的污染源附近;直排点源对环境的影响较小,污染主要集中在下风向.     

Characterizing the source/sink behavior of double-layer building materials

A model is developed to predict the rate of mass transfer between a double-layer material and indoor air. The model allows non-uniform initial material-phase concentrations in each of the two layers and a transient influent gas-phase concentration to be considered. This model builds on a recently validated single-layer model and should prove useful in predicting the behavior of double-layer material assemblies. Many indoor furnishings and building structures are comprised of layers of different material. The approach taken here represents a first step in the development of a more generally applicable multi-layer model. An analytical solution to the double-layer model is obtained and a parametric analysis is performed illustrating the behavior of the model as a function of the primary model parameters. The paper concludes by examining the potential use of thin diffusion barriers to reduce material emission rates and a hypothetical example of emissions from an adhesive that is part of an adhesive/material assembly.     

Large outdoor chamber experiments and computer simulations: (I) Secondary organic aerosol formation from the oxidation of a mixture of d-limonene and α-pinene

This work merges kinetic models for α-pinene and d-limonene which were individually developed to predict secondary organic aerosol (SOA) formation from these compounds. Three major changes in the d-limonene and α-pinene combined mechanism were made. First, radical–radical reactions were integrated so that radicals formed from both individual mechanisms all reacted with each other. Second, all SOA model species from both compounds were used to calculate semi-volatile partitioning for new semi-volatiles formed in the gas phase. Third particle phase reactions for particle phase α-pinene and d-limonene aldehydes, carboxylic acids, etc. were integrated. Experiments with mixtures of α-pinene and d-limonene, nitric oxide (NO), nitrogen dioxide (NO₂), and diurnal natural sunlight were carried out in a dual 270 m³ outdoor Teflon film chamber located in Pittsboro, NC. The model closely simulated the behavior and timing for α-pinene, d-limonene, NO, NO₂, O₃ and SOA. Model sensitivities were tested with respect to effects of d-limonene/α-pinene ratios, initial hydrocarbon to NO_x (HC₀/NO_x) ratios, temperature, and light intensity. The results showed that SOA yield (Y_SOA) was very sensitive to initial d-limonene/α-pinene ratio and temperature. The model was also used to simulate remote atmospheric SOA conditions that hypothetically could result from diurnal emissions of α-pinene, d-limonene and NO_x. We observed that the volatility of the simulated SOA material on the aging aerosol decreased with time, and this was consistent with chamber observations. Of additional importance was that our simulation did not show a loss of SOA during the daytime and this was consistent with observed measurements.