模拟实验研究煤矿酸性水中Co、Ni、Zn、Cd、Al、Cr、As、Pb可溶性金属迁移行为

通过模拟煤矿酸性水环境,对来自2个不同产地的煤系非均质黄铁矿样品进行了不同固液比的淋滤实验,对反应体系物理化学状态以及其中的Co、Ni、Zn、Cd、Al、Cr、As、Pb8种元素的释放行为进行了长达312h跟踪检测和对比.结果显示,在2种不同来源的煤系黄铁矿样品反应体系中,Co、Ni、Zn、Cd的释放行为均为持续升高,说明这些元素的释放受体系中物理化学状态的影响相对较小,在液相中具有较高的迁移行为;Al、Cr、As、Pb在不同样品体系中的释放行为差异较大,受到体系pH值、吸附及共沉淀作用等因素的影响,是相对不易迁移的元素.煤矿酸性水环境中元素释放和迁移行为主要受到黄铁矿的氧化还原反应速率、反应体系介质pH值和围岩矿物学性质3个宏观因素控制.     

Estimating the economic value of improvements in river ecology using choice experiments: an application to the water framework directive

The Water Framework Directive is a major regulatory reform of water resources management within the European Union. Integrated catchment management plans must be prepared for all river basins, in order to achieve 'good ecological status' in all EU waters. Ecological status is a broader measure of water quality than the chemical and biological measures that were previously dominant. The Directive calls for a consideration of the economic costs and benefits of improvements to ecological status. In this paper, we use the choice experiment method to estimate the value of improvements in three components of ecological status. Given the high resource cost of valuation studies, benefits transfer methods will be needed in implementing the Directive. We thus also test the ability of choice experiments for benefits transfer across two very similar rivers in the UK.     

臭氧氧化地下水石油污染物的动态模拟试验

针对被石油类污染物严重污染的淄博市水源地下水进行了Ｏ３净化技术的动态试验研究,建立了一套模拟地下水运动的室内装置。通过在模拟装置中的动态Ｏ３化反应表明：Ｌ３对含水层油污染的处理是有效的;在污染物肖度１－５ｍｇ／Ｌ和Ｏ３投加量４５ｍｇ／Ｌ,水层表面浮油去除率达９０％。     

Including risk in stated-preference economic valuations: Experiments on choices for marine recreation

Stated-preference surveys for the economic valuation of environmental resources typically assume no uncertainty in the hypothetical valuation scenarios. However, the outcomes of environmental policies are uncertain. We explored the effects of including information on probabilities of attribute improvement and provision in choice experiments. Our results suggest that stating explicitly a high probability for the occurrence of the valuation scenario can improve the goodness of fit of choice models and the consistency of choices. As the general public becomes more aware of the uncertainty of environmental outcomes under global change, omitting information on scenario risk may contribute to hypothetical bias and impair the validity of stated-preference valuations.     

适用于移动平台的河流突发污染溯源算法研究

提出了一种适用于小型移动水质检测平台的一维均一地表水单点源污染物溯源新算法,即通过计算污染物在时间域和空间域的质量浓度导数来反推污染物初始排放点的位置、排放时间及污染物总量.首先,通过算例仿真研究表明,此方法具有较高的溯源精度(与理论距离偏差在10％以内).其次,结合目前移动检测的实际限制(平台长度、取样时间等),对算法中涉及的采样时间、距离等因素的选择进行分析,对移动平台的溯源操作给出了优化建议,以确保有较高的溯源精度.最后,通过实验室水槽缩尺模型试验验证了算法有较高溯源精度(最大偏差在30％以内),从而在原理上证明了该算法适用于特定流域下的移动水质污染溯源.     

Optimized quantity-within-distance models of spatial welfare heterogeneity

Spatial welfare heterogeneity is frequently modeled within stated preference analysis as a function of discrete or continuous distance between households and affected resources. A common example is distance-decay analysis. Although distance-based models such as these are easily estimated, the ubiquity of this paradigm can lead to analyses that overlook other forms of analysis with equal or greater relevance. This paper develops an alternative approach to spatial heterogeneity in stated preference willingness to pay (WTP) based on the quantity or area of an affected resource surrounding each respondent at an optimized distance band or radius, with distance bands optimized using a grid-search algorithm that maximizes model likelihood. Methods and results are illustrated using a choice experiment on riparian land restoration in Maine, USA. The resulting quantity-within-distance model identifies systematic spatial patterns that are undetectable using distance-based analysis and directly relevant for welfare analysis.     

An experimental analysis of compliance in dynamic emissions markets

Two important design elements for emission trading programs are whether and to what extent firms are able to bank emissions permits, and how these programs are to be enforced. In this paper we present results from laboratory emissions markets designed to investigate enforcement and compliance when these markets allow permit banking. Banking is motivated by a decrease in the aggregate permit supply in the middle of multi-period trading sessions. Consistent with theoretical insights, our experiments suggest that high permit violation penalties have little deterrence value in dynamic emissions markets, and that the main challenge of enforcing these programs is to motivate truthful self-reports of emissions.     

Human behaviour and evacuation time for large underground comprehensive buildings during fire risk process

Human factors play an indispensable role in process safety during fire risk process. Fire evacuation of underground comprehensive buildings is a critical consideration for practical importance. Here, evacuation experiments were conducted in the Guangzhou East Railway Station Plaza, a large underground comprehensive building in Guangdong, China, with the plaza occupants as the participants. The evacuation factors, namely evacuation time and evacuee-selected evacuation routes, were evaluated using empirical equations (the Togawa model and the Melinek and Booth model) and evacuation modelling software (EVACNET 4 and composite occupant evacuation model). The experimental data were used to verify the empirical equations and evacuation models and to modify specific empirical parameters. The effect on escape route judgement and selection under emergency situations was analysed. The results demonstrated that direct access to outdoor exits could considerably reduce evacuation time. The experimental N and t_s were 1 person/m·s and 28 s, respectively. The total evacuation time was 281 s, and the EVACNET 4 and composite models’ simulations of safe evacuation were 285–290 s, which was consistent with the experimental data—validating the high accuracy and applicability of the models.     

In-Situ Phytoremediation of Pahs Contaminated Soils Following a Bioremediation Treatment

Phytoremediation of pollutants in soils is an emerging technology, using different soil-plant interaction properties. For organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), phytodegradation seems to be the most promising approach. It occurs mostly through an increase of the microbial activity in the plant rhizosphere, allowing the degradation of organic substances, a source of carbon for soil microbes. Despite a large amount of available data in the literature concerning laboratory and short term PAH phytodegradation experiments, no actual field application of such technique was previously carried out. In the present study, a soil from a former coking plant was used to evaluate the feasibility and the efficiency of PAH phytodegradation in the field during a three years trial and following a bioremediation treatment. Before the phytoremediation treatment, the soil was homogenized and split into six independent plots with no hydrological connections. On four of these plots, different types of common plant species were sowed: mixture of herbaceous species, short cut (P1), long cut (P2), ornamental plants (P3) and trees (P4). Natural vegetation was allowed to grow on the fifth plot (P5), and the last plot was weeded (P6). Each year, representative sampling of two soil horizons (0–50 and 50–100 cm) was carried out in each plot to characterize the evolution of PAHs concentration in soils and in soils solution obtained by lixiviation. Possible impact of the phytoremediation technique on ecosystems was evaluated using different eco- and genotoxicity tests both on the soil solid matrix and on the soil solution. For each soil horizon, comparable decrease of soil total PAHs concentrations were obtained for three plots, reaching a maximum value of 26% of the initial PAHs concentration. The decrease mostly concerned the 3 rings PAHs. The overall low decrease in PAHs content was linked to a drastic decrease in PAHs availability likely due to the bioremediation treatment. However, soil solutions concentration showed low values and no signficant toxicity was characterized. The mixture of the herbaceous species seemed to be the most promising plants to be used in such procedure.