Computer simulation model for determining reclamation liability costs of the Ekati Diamond Mine™ in the Northwest Territories,Canada

Estimation of closure liabilities for financial reporting and security deposits in the mining industry is often based on past estimates or deterministic models. These methods are limited in their ability to account for the variability of contributing costing factors. In 2001, Komex International Ltd. developed a Monte Carlo simulation (MCS) model to provide a best estimate for the reclamation liabilities of the Ekati Diamond Mine™ (BHP Billiton Diamonds Inc.). The model was built upon Decisioneering's^® Crystal Ball risk analysis and forecasting software to simulate the various facets of the mine's closure plans and reclamation activities. Reclamation activities included decommissioning, demolition, site remediation, reclamation and post closure monitoring for seven mine pits and related infrastructures over four time periods. The model predicted the median, 10th and 90th percentile costs and other statistical measures. A sensitivity analysis was also conducted to identify the most significant cost contributors. This type of model offers many advantages for companies in determining probable costs of future environmental activities. Through the identification of cost contributors, work scenarios, computer code and modeling software, a MCS model can simulate a wide range of probable costs and scenarios. Probabilistic models are more effective at incorporating risk and uncertainty in liability estimates than deterministic estimation tools that rely heavily on global contingencies to account for risk.     

The effect of octopamine on behavioral responses of free-foraging bumblebees to a change in food source profitability

The invertebrate neuromodulator octopamine is known to be involved in bees' associative learning, enhancing the responsiveness of a bee to a conditioned stimulus. In this study, we tested the effect of octopamine on the choice behavior of free-flying bumblebees using a two-phase experiment in an array of artificial flowers. During the first phase of the experiment, the bee was allowed to collect octopamine-laden sugar water from two types of equally rewarding flowers (yellow versus blue). In the second phase, one type of flower was set to be unrewarding. The behavior of the bee (proportion of visits to the unrewarding flowers) over the two phases was fitted to a sigmoid regression model. Our results show that octopamine had no significant effect on the bees' equilibrium choice or on the overall rate of the behavioral change in response to the change in reward. Rather, octopamine significantly affected the time interval between the change in reward status and the initiation of behavioral change in the bee.     

模拟消落带水华暴发行为的数值沙堆模型

以长江最大支流汉江近年来水华污染的现场资料为例,通过氮磷浓度、水温、流速和光照等实测数据构建了消落带开放水域环境体系的数值沙堆模型,描述了藻类生长及水华暴发的动力学机制;利用数值沙堆系统崩塌行为反映出的频率-尺度幂律关系作为判断消落带水域是否暴发水华以及规模大小的依据,采用有限尺度标度分析从不同侧面验证了水华暴发系统的自组织临界性,并揭示出各种拟合参数与水华暴发规模之间的定量关系.研究表明,沙堆模型如果存在良好的幂律关系,相应的消落带水域将暴发水华,且幂律指数越大,水华污染程度越严重.     

Reprint of: Linking conservation and welfare: A theoretical model with application to Nepal

Theoretical articles linking conservation and welfare find a negative relationship between these two variables while empirical studies show that land protection may be positively related to welfare. Several authors attribute this empirical result to the development of ecotourism in protected areas. We thus argue that the gap between the theory and existing empirical results is partly explained by the fact that most theoretical models do not account for a productive activity on protected land. Therefore, we develop a theoretical model in which conservation allows developing an alternative sector and show that the relationship between conservation and welfare is U-shaped. We test this theoretical prediction using Nepalese data and find that conservation combined with ecotourism is indeed positively related to local welfare.     

Incorporating putatively neutral and adaptive genomic data into marine conservation planning

The availability of genomic data for an increasing number of species makes it possible to incorporate evolutionary processes into conservation plans. Recent studies show how genetic data can inform spatial conservation prioritization (SCP), but they focus on metrics of diversity and distinctness derived primarily from neutral genetic data sets. Identifying adaptive genetic markers can provide important information regarding the capacity for populations to adapt to environmental change. Yet, the effect of including metrics based on adaptive genomic data into SCP in comparison to more widely used neutral genetic metrics has not been explored. We used existing genomic data on a commercially exploited species, the giant California sea cucumber (Parastichopus californicus), to perform SCP for the coastal region of British Columbia (BC), Canada. Using a RAD-seq data set for 717 P. californicus individuals across 24 sampling locations, we identified putatively adaptive (i.e., candidate) single nucleotide polymorphisms (SNPs) based on genotype–environment associations with seafloor temperature. We calculated various metrics for both neutral and candidate SNPs and compared SCP outcomes with independent metrics and combinations of metrics. Priority areas varied depending on whether neutral or candidate SNPs were used and on the specific metric used. For example, targeting sites with a high frequency of warm-temperature-associated alleles to support persistence under future warming prioritized areas in the southern coastal region. In contrast, targeting sites with high expected heterozygosity at candidate loci to support persistence under future environmental uncertainty prioritized areas in the north. When combining metrics, all scenarios generated intermediate solutions, protecting sites that span latitudinal and thermal gradients. Our results demonstrate that distinguishing between neutral and adaptive markers can affect conservation solutions and emphasize the importance of defining objectives when choosing among various genomic metrics for SCP.     

Application of CALINE4 to roadside NO/NO2 transformations

The CALINE4 roadway dispersion model has been applied to concentrations of NO_x and NO₂ measured near Gandy Boulevard in Tampa, FL (USA) during May 2002. A NO_x emission factor of 0.86 gr mi⁻¹ was estimated by treating NO+NO₂ (NO_x) as a conserved species and minimizing the differences between measured and calculated NO_x concentrations. This emission factor was then used to calculate NO₂ concentrations using the NO/NO₂ transformation reactions built into CALINE4. A comparison of measured and calculated NO₂ concentrations indicates that for ambient O₃ concentrations less than 40 ppb the model under-predicts the chemical transformation of NO. The enhanced transformation of NO may be due to reactions of NO with oxidants such as peroxy radicals that are present either in the atmosphere or in vehicle exhaust.     

Interpreting and using outputs from the Canadian Forest Fire Danger Rating System in research applications

Understanding and being able to predict forest fire occurrence, fire growth and fire intensity are important aspects of forest fire management. In Canada fire management agencies use the Canadian Forest Fire Danger Rating System (CFFDRS) to help predict these elements of forest fire activity. In this paper a review of the CFFDRS is presented with the main focus on understanding and interpreting Canadian Fire Weather Index (FWI) System outputs. The need to interpret the outputs of the FWI System with consideration to regional differences is emphasized and examples are shown of how the relationship between actual fuel moisture and the FWI System’s moisture codes vary from region to region. Examples are then shown of the relationship between fuel moisture and fire occurrence for both human- and lightning-caused fire for regions with different forest composition. The relationship between rate of spread, fuel consumption and the relative fire behaviour indices of the FWI System for different forest types is also discussed. The outputs of the CFFDRS are used every day across Canada by fire managers in every district, regional and provincial fire management office. The purpose of this review is to provide modellers with an understanding of this system and how its outputs can be interpreted. It is hoped that this review will expose statistical modellers and other researchers to some of the models used currently in forest fire management and encourage further research and development of models useful for understanding and managing forest fire activity.

Heat generation of refuse derived fuel with water

In order to clarify the scenario of fires and accidents resulting from spontaneous combustion of Refuse Derived Fuel (RDF), exothermic phenomenon of RDF with water at ambient temperature was characterized by Calvet calorimeter (C 80 and MS 80), Thermal Activity Monitor and Dewar. The spontaneous combustion characteristic of RDF without additional water was examined by Thermogravimetry and Differential Thermal Analysis and Spontaneous Ignition Tester. The experimental results show the heat generation of RDF with different water content occurred instantly after additional water was added into RDF, while no exothermic phenomenon can be observed if no additional water was added into RDF at room temperature. It means that the self-heating of RDF does not only result from fermentation of RDF because of the prompt heat generation and temperature rise of RDF with water. It is possible that the self-heating of RDF results from heat of wetting first when additional water/vapor is absorbed by RDF. The further quantitative analysis for the self-heating of RDF with water/vapor should be made to explain the process of spontaneous combustion of RDF in detail.     

THE TIGER IN THE DINING ROOM: DESIGNING AND EVALUATING INTEGRATED ASSESSMENTS OF ATMOSPHERIC CHANGE

Integrated assessments (IAs) and integrated assessment models (IAMs) arerecent responses to the inter-disciplinary challenges provided by complexglobal environmental issues such as atmospheric change. This paper discussesan array of integrated assessments, providing an overview of the role of IAsas bridges or foundations for epistemic communities. Formal as well associal, political, and ethical issues are presented. As well as a definition of anIA and an IAM, different forms and approaches of current or proposed IAsare reviewed. Particular stress is laid on the need to maintain the integrity ofthe diverse components of an IA. Finally, reference is made to the need tounderstand the underlying ethical and normative concerns that have promotedthe current interest in IA.