Community dynamics of ammonia oxidizing bacteria in a full-scale wastewater treatment system with nitrification stability

To determine whether the functional stability of nitrification was correlated to a stable community structure of ammonia oxidizing bacteria (AOB) in a full-scale wastewater treatment plant, the AOB community dynamics in a wastewater treatment system was monitored over one year. The community dynamics were investigated using specific PCR followed by terminal restriction fragment length polymorphism (T-RFLP) analysis of the amoA gene. The T-RFLP results indicated that during the period of nitrification stability, the AOB community structure in the full-scale wastewater treatment system was relatively stable, and the average change rate every 15 d of the system was 6.6%±5.8%. The phylogenetic analysis of the cloned amoA gene showed clearly that the dominant AOB in the system was Nitrosomonas spp. The results of this study indicated that throughout the study period, the AOB community structure was relatively stable in the full-scale wastewater treatment system with functional stability of nitrification.     

Comparing measured and modelled forest carbon stocks in high-boreal forests of harvest and natural-disturbance origin in Labrador, Canada

Understanding the effects of disturbance regimes on carbon (C) stocks and stock changes is a prerequisite to estimating forest C stocks and fluxes. Live-tree, dead-tree, woody debris (WD), stump, buried wood, organic layer, and mineral soil C stock data were collected from high-boreal black spruce (Picea mariana (Mill.) B.S.P.) stands of harvest and fire origin and compared to values predicted by the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3); the core model of Canada's National Forest Carbon Monitoring, Accounting and Reporting System. Data comparing the effect of natural and anthropogenic disturbance history on forest C stocks are limited, but needed to evaluate models such as the CBM-CFS3. Results showed that adjustments to the CBM-CFS3 volume-to-biomass conversion and partitioning parameters were required for the non-merchantable and branch C pools to accurately capture live-tree C stocks in the studied black spruce ecosystems. Accuracy of the CBM-CFS3 modelled estimates of dead organic matter and soil C pools was improved relative to regional default parameters by increased snag fall and >10 cm WD base decay rates. The model evaluation process also highlighted the importance of developing a bryophyte module to account for bryophyte C dynamics and the physical burial of woody debris by bryophytes. Modelled mineral soil C estimates were improved by applying a preliminary belowground slow C pool base decay rate optimized for the soil type of the studied sites, Humo-Ferric Podzols.     

Quantifying parameter uncertainty in a coral reef model using Metropolis-Coupled Markov Chain Monte Carlo

Coral reefs are threatened ecosystems, so it is important to have predictive models of their dynamics. Most current models of coral reefs fall into two categories. The first is simple heuristic models which provide an abstract understanding of the possible behaviour of reefs in general, but do not describe real reefs. The second is complex simulations whose parameters are obtained from a range of sources such as literature estimates. We cannot estimate the parameters of these models from a single data set, and we have little idea of the uncertainty in their predictions.We have developed a compromise between these two extremes, which is complex enough to describe real reef data, but simple enough that we can estimate parameters for a specific reef from a time series. In previous work, we fitted this model to a long-term data set from Heron Island, Australia, using maximum likelihood methods. To evaluate predictions from this model, we need estimates of the uncertainty in our parameters. Here, we obtain such estimates using Bayesian Metropolis-Coupled Markov Chain Monte Carlo. We do this for versions of the model in which corals are aggregated into a single state variable (the three-state model), and in which corals are separated into four state variables (the six-state model), in order to determine the appropriate level of aggregation. We also estimate the posterior distribution of predicted trajectories in each case.In both cases, the fitted trajectories were close to the observed data, but we had doubts about the biological plausibility of some parameter estimates. We suggest that informative prior distributions incorporating expert knowledge may resolve this problem. In the six-state model, the posterior distribution of state frequencies after 40 years contained two divergent community types, one dominated by free space and soft corals, and one dominated by acroporid, pocilloporid, and massive corals. The three-state model predicts only a single community type. We conclude that the three-state model hides too much biological heterogeneity, but we need more data if we are to obtain reliable predictions from the six-state model. It is likely that there will be similarly large, but currently unevaluated, uncertainty in the predictions of other coral reef models, many of which are much more complex and harder to fit to real data.     

A new approach to the analysis of adjacencies: Potentials for landscape insights

Spatial adjacencies are a key-issue in environmental studies. Adjacency effects have been amply observed for biotic (plants and animals) and abiotic components of ecosystems. Particularly well-documented are the effects from human manufactures onto the contiguous vegetation mosaics of natural and semi-natural areas.In this work we first propose and reformulate association rules analysis (ARA), a relatively new data mining algorithm with very limited scientific applications so far, in the form of an in-depth investigation method of the spatial pattern of landcover and vegetation maps. We applied ARA to two very different study areas in Northern Italy, the first (Ceno valley) having a substantial human footprint and mapped at 1:25,000 scale, the second (Foses valley) being almost natural and mapped at 1:5000 scale.We were able to: (a) detect the entire network of spatial adjacencies among landcover types and (b) quantify the frequency and strength of detected adjacencies. Based on our spatial analysis, we also advanced hypotheses on both natural and man-driven vegetation dynamics. In addition, ARA allowed us to propose an index of naturality based on the discovered contiguities.Results show the skill of the proposed approach to characterize landcover spatial patterns for both mid-resolution and high-resolution maps. Furthermore the proposed approach bears a general interest, since it can be applied to the analysis of any landcover map.     

Ecotoxicological effects of Trichloroethene upon plankton

A case study in an experimental pond was performed to evaluate the ecotoxic effects of Trichloroethene (TRI) upon the population density and productivity of phyto‐ and zooplankton. TRI was continuously released into two pond enclosures over 11 weeks (mean concentrations 1.5 and 7.5 mg/l). The chronic chemical treatment showed distinctive toxic influences upon the biota. Following the high TRI concentration, the phytoplankton density slightly increased; the productivity per single cells, however, was significantly reduced compared to the controls and the low TRI concentration. Cryptophyceae were the most sensitive algae taxa. The density and reproductivity of Daphniae and Phyllopodae decreased by the high TRI concentration. Most of the Rotatoriae were not negatively influenced. With increasing TRI concentrations two different bacteria forms showed a mass development. Small amounts of Trichloroacetic acid were detected in both enclosures as a conversion product of TRI (～3 μg/l after 80 days treatment).     

Post-seismic allocation of medical staff in the Longmen Shan fault area: case study of the Lushan Earthquake

In April 2013, a 7.0 magnitude earthquake struck along the Longmen Shan fault in the city of Ya'an, Sichuan province, China, causing 200 deaths, 11,470 injuries and 21 people to go missing. As no scientific disaster management studies have been done on medical staff dynamic behavior in the Longmen Shan fault area, this paper develops a system dynamics (SD) model to simulate the relief activities in the area after the 2008 Sichuan Earthquake shook Wenchuan County. Based on this SD model, the simulation showed that the results regarding the cumulative number of deaths and the final death toll fit the reality well for the 2008 Sichuan Earthquake in the Longmen Shan fault area. Findings from the simulation confirmed the best ratio of medical staff to rescue workers. After implementing the findings for the medical relief work at the 2013 Sichuan Lushan Earthquake, reasonable earthquake rescue policies were developed for the Longmen Shan fault area. The SD model demonstrated that it was possible to predict the optimum number of medical staff and that medical staff need to be trained to improve their treatment abilities. Furthermore, it is suggested that search and rescue workers should also assist in restoring road transport during any medical relief activities in the Longmen Shan fault area. These policies can be generalized to other earthquake relief activities in the Longmen Shan fault area as well as being a valuable reference for similar mountainous earthquake areas.     

苹果和土壤中丙森锌的消解动态及残留规律

研究了苹果和土壤中丙森锌残留的气相色谱分析方法,及其代谢物乙撑硫脲的高效液相色谱分析方法,并在天津、山东烟台和陕西咸阳进行了苹果和土壤中丙森锌及其代谢物乙撑硫脲残留消解动态和残留规律田间试验研究.结果表明,在0.05—2 mg.kg-1的加标水平下,苹果和土壤中丙森锌的加标回收率分别为77.12%—92.85%和9.24%—94.68%,变异系数分别为3.30%—6.56%和3.29%—5.29%;在0.05—1 mg.kg-1的加标水平下,苹果和土壤中乙撑硫脲的加标回收率分别为80.91%—97.47%和84.11%—99.97%,变异系数分别为3.23%—3.82%和2.80%—3.40%.苹果和土壤中丙森锌和乙撑硫脲的最小检出量分别为5.0×10-10g和1.0×10-10g,其中苹果和土壤中丙森锌的最低检出浓度为0.025 mg.kg-1,乙撑硫脲的最低检出浓度为0.005 mg.kg-1.按1.5倍推荐剂量600倍稀释液在苹果上施用65%戊唑醇.丙森锌可湿性粉剂1次,丙森锌在苹果和土壤中的残留消解半衰期分别为6.0—6.8 d和8.7—10.1 d.按推荐剂量和1.5倍推荐剂量在苹果上各施用65%戊唑醇.丙森锌可湿性粉剂3—4次,2次施药间隔为10 d,距最后一次施药21 d时,丙森锌在苹果中的最高残留量低于我国农业行业标准规定的最大残留限量2 mg.kg-1.     

概率火灾安全分析方法研究

为分析和评估火灾对设备、建筑物等敏感目标结构安全的影响,结合化工定量风险评估方法和气体爆炸概率安全分析方法,提出概率火灾安全分析策略和实施流程。该方法包括火灾危害辨识、泄漏速率计算、火灾后果模拟、频率分析、绘制频率超越热载荷曲线、结构响应分析等关键步骤。以某柴油罐区为例,通过频率分析和火灾模拟,绘制出频率超越热载荷曲线,假定火灾风险可接受准则为10-4/a,求得对应的可信热载荷为21 kW/m2,并以此值作为结构热响应分析的输入参数。火灾概率安全分析方法侧重于描述火灾热辐射强度及其对应的发生可能性,判定敏感目标遭遇的可信火灾热载荷强度和结构热响应行为,评估消防减灾措施效果,确保结构完整性和可用性,不评价工艺系统潜在火灾风险的高低。     

Study of chemical supply system of high-tech process using inherently safer design strategies in Taiwan

The photoelectric, semiconductor and other high-tech industries are Taiwan's most important economic activities. High-tech plant incidents are caused by hazardous energy, even when that energy is confined to the inside of the process machine. During daily maintenance procedures, overhauling or troubleshooting, engineers entering the interior of the machines are in direct contact with the source of the energy or hazardous substances, which can cause serious injury. The best method for preventing such incidents is to use inherently safer design strategies (ISDs); this approach can fully eliminate the dangers from the sources of hazardous energy at a facility.This study first conducts a lithography process hazard analysis and compiles a statistical analysis of the causes of the fires and losses at high-tech plants in Taiwan since 1996, the aim being to establish the necessary improvement measures by using the Fire Dynamics Simulation (FDS) to solve relevant problems. The researchers also investigate the lithography process machine in order to explore carriage improvement measures, and analyse the fires' causes and reactive materials hazardous properties, from 1996 to 2012. The effective improvement measures are established based on the accident statistics. The study site is a 300 mm wafer fabrication plant located in Hsinchu Science Park, Taiwan.After the completion of the annual maintenance jobs improvement from September 2011 to December 2012, the number of lithography process accidents was reduced from 6 to 1. The accident rate was significantly reduced and there were no staff time losses for a continuous 6882 h. It is confirmed that the plant safety level has been effectively enhanced. The researchers offer safety design recommendations regarding transport process appliances, chemical storage tanks, fume cupboard devices, chemical rooms, pumping equipment, transportation pipelines, valve manual box (VMB) process machines and liquid waste discharge lines. These recommendations can be applied in these industries to enhance the safety level of high-tech plants, facilities or process systems.     

反机场跑道润滑技术研究

反机场跑道润滑是一种新概念非致命性武器技术.本文以硬脂酸、甲基硅油及其他添加剂在常压下合成了一种新型硅油脂,并将其与几种常用润滑剂进行润滑摩擦系数的实验对比.通过摩擦学实验得到了0～72 h内其摩擦系数的变化曲线,并从分子结构角度对实验结果进行理论分析.结果表明,在对混凝土-橡胶轮胎摩擦副的润滑中,自制硅油脂可以使其摩擦系数保持在制动困难状态(μ≤0.35),并且可以维持较长时间(t≥72 h).综合各因素,它在机场跑道润滑过程中具有明显的优势,具有军事应用前景.