TSP日平均浓度监测采样时间有效性研究

通过对诸暨市城区空气中总悬浮颗粒物（ＴＳＰ）采用不同的自动连续采样时间获得的日平均浓度对比研究发现，每日采样的时间只有达到１８小时以上，才能体现真实的日平均浓度。     

一种用粪便样方法估计林麝种群密度的新方法

数量(密度)特征是动物种群的一个重要特征，是定点研究一个野生种群生态的一项非常重要的基础工作．其数量和年龄结构为进一步分析其种群的密度、移动、巢域和核域，尤其是为种群动态提供依据，也是珍稀动物保护和资源动物管理利用的先行工作和重要组成部份．关于野生动物种群数量的具体统计方法，有不少的文章报道，然而从动物的空间分布格局来研究大型脊椎动物却较为少见，这主要是受研究方法的限制．为此，作者对此进行了改进，提出了一种新的研究方法：临时空间样方法，并将其应用到冶勒自然保护区林麝的数量调查研究中去．结果表明：(1)集聚分布指数CA=12．09，说明冶勒自然保护区的林麝有较高的集聚度；(2)林麝粪堆在野外的分布属于聚集分布，并与负二项分布拟合较好；(3)在冶勒自然保护区，生活有62～98只左右的林麝，其密度为：1．0～1．6只／km^2．林麝在冶勒自然保护区呈现聚积分布的原因是由于环境和人类活动因素造成的．图1表2参24     

Assessing Habitat Quality for a Migratory Songbird Wintering in Natural and Agricultural Habitats

Abstract:  As tropical forests are cleared, a greater proportion of migratory songbirds are forced to winter in agricultural and disturbed habitats, which, if poorer in quality than natural forests, could contribute to population declines. We compared demographic indicators of habitat quality for a focal species, the American Redstart ( Setophaga ruticilla ), wintering in Jamaican citrus orchards and shade coffee plantations with those in four natural habitats: mangrove, coastal scrub, coastal palm, and dry limestone forests. Demographic measures of habitat quality included density, age and sex ratio, apparent survival, and changes in body mass. Measures of habitat quality for redstarts in citrus and coffee habitats were generally intermediate between the highest (mangrove) and lowest (dry limestone) measurements from natural habitats. The decline in mean body mass over the winter period was a strong predictor of annual survival rate among habitats, and we suggest that measures of body condition coupled with survival data provide the best measures of habitat quality for nonbreeding songbirds. Density, which is far easier to estimate, was correlated with these more labor-intensive measures, particularly in the late winter when food is likely most limiting. Thus, local density may be useful as an approximation of habitat quality for wintering migrant warblers. Our findings bolster those of previous studies based on bird abundance that suggest arboreal agricultural habitats in the tropics can be useful for the conservation of generalist, insectivorous birds, including many migratory passerines such as redstarts.     

Mapping lightning/human-caused wildfires occurrence under ignition point location uncertainty

Fire managers need to study fire history in terms of occurrence in order to understand and model the spatial distribution of the causes of ignition. Fire atlases are useful open sources of information, recording each single fire event by means of its geographical position. In such cases the fire event is considered as point-based, rather than area-based data, completely losing its surface nature. Thus, an accurate method is needed to estimate continuous density surfaces from ignition points where location is affected by a certain degree of uncertainty. Recently, the fire scientific community has focused its attention on the kernel density interpolation technique in order to convert point-based data into continuous surface or surface-data. The kernel density technique needs a priori setting of smoothing parameters, such as the bandwidth size. Up to now, the bandwidth size was often based on subjective choices still needing expert knowledge, eventually supported by empirical decisions, thus leading to serious uncertainties. Nonetheless, a geostatistical model able to describe the point concentration and consequently the clustering degree is required. This paper tries to solve such issues by implementing the kernel density adaptive mode. Lightning/human-caused fires occurrence was investigated in the region of Aragón's autonomy over 19 years (1983–2001) using 3428 and 4195 ignition points respectively for the two causes of fire origin. An analytical calibration procedure was implemented to select the most reliable density surfaces to reduce under/over-density estimation, overcoming the current drawbacks to define it by visual inspection or personal interpretation. Besides, ignition point location uncertainty was investigated to check the sensitivity of the proposed model. The different concentration degree and the dissimilar spatial pattern of the two datasets, allow testing the proposed calibration methodology under several conditions. After having discovered the slight sensitivity of the model to the exact point position, the obtained density surfaces for the two causes were combined to discover hotspot areas and spatial patterns of the two causes. Evident differences in spatial location of the origin causes were noted and described. The general trend follows the geographical features and the human activity of the study areas. The proposed technique should be promising to support decision-making in wildfire prevention actions, because of the occurrence map can be used as a response variable in fire risk predicting models.     

Removal of boron by electrocoagulation

Boron compounds are used in many manufacturing products and may be introduced into the environment in the form of hazardous materials. Here the feasibility of removal of boron from aqueous solutions by electrocoagulation was investigated. The process was examined under various factors in order to assess optimal operating conditions. The results showed that electrocoagulation for boron removal depends on current density, initial concentration and time. Under a current density of 30 mA/cm² the percentage of boron removal from aqueous solutions is in the range of 92–96%.     

Random denominators and the analysis of ratio data

Ratio data, observations in which one random value is divided by another random value, present unique analytical challenges. The best statistical technique varies depending on the unit on which the inference is based. We present three environmental case studies where ratios are used to compare two groups, and we provide three parametric models from which to simulate ratio data. The models describe situations in which (1) the numerator variance and mean are proportional to the denominator, (2) the numerator mean is proportional to the denominator but its variance is proportional to a quadratic function of the denominator and (3) the numerator and denominator are independent. We compared standard approaches for drawing inference about differences between two distributions of ratios: t-tests, t-tests with transformations, permutation tests, the Wilcoxon rank test, and ANCOVA-based tests. Comparisons between tests were based both on achieving the specified alpha-level and on statistical power. The tests performed comparably with a few notable exceptions. We developed simple guidelines for choosing a test based on the unit of inference and relationship between the numerator and denominator.     

Influence of Downstream Control and Limited Depth on Flow Hydrodynamics of Impinging Buoyant Jets

Much study has been performed on the mixing properties of submerged, turbulent buoyant jets. It is safe to say that the problem of estimating dilution rates in vertical buoyant jets spreading in an `infinitely deep' ambient water has been more than adequately resolved by previous researchers. However, the majority of environmental applications involve discharges into ambient waters of finite depths in which a bounding surface serves to re-direct the impinging buoyant jet horizontally into a radial spreading layer. Previous research indicates that this impinging jet undergoes additional mixing before buoyancy stabilizes vertical mixing and confines the spreading layer to the vicinity of the bounding surface. Unfortunately, the conceptualization and subsequent mathematical modeling of this additional mixing phenomenon is surrounded by considerable amount of disagreement between researchers. The purpose of this study is to provide, by means of velocity and concentration profile measurements, independent experimental evidence for the existence of a critical flow state immediately downstream of the active mixing zone in the horizontally flowing, radial flow that forms after impingement. It is further shown that this critical flow state must be expressed in terms of a composite Froude Number that takes into account the possibility of a non-zero exchange layer flow. Finally, the influence of the presence of a sill-like topographic downstream control on the criticality of the radial flow immediately downstream of the active mixing zone is also investigated.     

北京城市大气污染源的暴露效率研究

为了精确地估算产业部门不同类别与特征的大气污染源对指定区域的污染强度 ,采用暴露效率概念及其研究方法。以北京城区为例 ,应用大气污染扩散模型ISCST3,由污染排放数据、全年逐时气象数据以及市区人口分布 ,求得 1999年各污染源对北京市区SO2 ,PM10 ,NOx 等污染物浓度的贡献率和北京城区居民的暴露效率。研究表明 ,不同行业污染源导致SO2 暴露效率在 2× 10 -6～ 2 0× 10 -6之间 ,PM10 、NOx 暴露效率在 2× 10 -6～ 5 0× 10 -6之间。采暖 ,交通等行业部门的污染源产生的暴露效率较大 ,而污染物排放量较大的污染源 (电厂 ) ,由于远离人口密集区并且排放高度较高 ,因此暴露效率较小。     

Earthquake hazard and vulnerability in the northeastern Mediterranean: the Corinth earthquake sequence of February-March 1981

Population density, building type and earthquake magnitude are the main factors on which the total building damage following an earthquake depend. For the Greece - Turkey region quantitative relations between these factors have been developed, which, in spite of the inaccuracies in the available data, allow crude estimates of the damage following a particular size earthquake to be made. This is demonstrated retrospectively for the Gulf of Corinth earthquakes in 1981.     

Human impact on beach and foredune microclimate on North Padre Island,Texas

The microclimate of beach and foredune areas of North Padre Island along the mid-Texas coast was found to be greatly modified by vehicular and pedestrian traffic during investigations made from late fall to early summer 1973–74. The primary effect of human activity on microclimate was expressed as reduced cover and species diversity of the vegetation. As the intensity of human activity increased, elevation, especially of areas near the beach, was decreased, whereas average wind velocities near the ground surface, evaporation, atmospheric salinity near the ground surface, wind-carried sand particles near the ground surface, soil salinity, soil pH, average soil temperature and range in temperature, soil bulk density, and soil-water contents were increased.