Strategies to lower methyl mercury concentrations in hydroelectric reservoirs and lakes: A review

Mercury (Hg) concentrations in fish in lakes are elevated due to increased global cycling of Hg. A special case of elevated Hg concentrations in fish occurs in new hydroelectric reservoirs because of increased rates of converting Hg in the environment into methyl mercury (MeHg). People and wildlife that eat fish from hydroelectric reservoirs have an elevated risk of accumulating too much MeHg. Demand for electrical energy is leading to the creation of new reservoirs. In 2005, Canada derived 60% of its electricity from hydroelectric reservoirs. As a result, hydroelectric companies and governing agencies are exploring strategies to lower MeHg contamination. Strategies may involve lowering the source of Hg before flooding, the rate of Hg methylation, or MeHg bioaccumulation and biomagnification. Possible strategies reviewed in this article include selecting a site to minimize impacts, intensive fishing, adding selenium, adding lime to acidic systems, burning before flooding, removing standing trees, adding phosphorus, demethylating MeHg by ultraviolet light, capping and dredging bottom sediment, aerating anoxic bottom sediment and waters, and water level management. A preventative strategy is to limit the flooded area, especially wetland areas. Flooded upland areas that contain less carbon produce MeHg for a shorter time than wetland areas. Run-of-the-river reservoirs contain lower MeHg concentrations than reservoirs that flood vast areas, at the cost of exporting MeHg downstream. Managing water levels to flush systems during times of peak MeHg production may have benefits for the reservoir, but also transports MeHg downstream. Intensive fishing can lower MeHg in food webs by increasing fish growth rate. Additions of selenium can lower MeHg bioaccumulation, but the mechanisms are not well established and excess selenium causes toxicity. Liming can lower fish Hg concentrations in lakes acidified with sulphuric and nitric acid. Burning before flooding can lower the production of MeHg, but MeHg bioaccumulation may increase. The most promising strategy will be one that is agreeable to all affected people.     

A national-scale GIS-based system for modelling impacts of land use on water quality

Management of freshwater quality requires modelling tools for rapid evaluation of land use and management scenarios. This paper presents the CLUES (Catchment Land Use and Environmental Sustainability) model to address this need. CLUES provides steady state, spatially distributed, integrated catchment models tightly coupled to GIS software to predict mean annual loads of total nitrogen, total phosphorus, sediments and E. coli, and concentration of nutrients throughout New Zealand (268,000 km²) with a subcatchment resolution of 0.5 km². CLUES also estimates potential nutrient concentrations for estuaries and provides key farm socio-economic indicators. The model includes a user interface for study area selection, scenario creation, data geo-visualisation, and export of results. It is pre-populated with spatial data and parameter values for New Zealand. Evaluation of the model and a summary of applications demonstrate the tractability and utility of national-scale rapid scenario assessment tools within a GIS framework.     

Carbon profiles of remote Australian Indigenous communities: A base for opportunities

A decision-making model was constructed to assist remote Australian Indigenous communities select appropriate climate change mitigation programs. The Resilient Community and Livelihood Asset Integration Model (ReCLAIM) comprises six steps that focus on community assets and aspirations. The second of these steps is to determine the baseline carbon profiles of communities based on six sources of carbon emissions: materials, construction processes, stationary energy, transport, water systems and waste. The methodology employed an annualised lifecycle analysis of housing materials and construction, and an annual inventory of other emission sources. Profiles were calculated for two remote communities and compared to the Australian average and also average electricity consumption by remote communities in the Northern Territory.The results, expressed in tonnes of carbon dioxide equivalent (tCO₂-e), showed that average household carbon profiles of the two communities (6.3 and 4.1 tCO₂-e/capita/yr) were generally lower than the Australian average (7.3 tCO₂-e/capita/yr). The stationary energy results revealed that infrastructure and building design could raise fuel consumption and costs, and therefore carbon emissions, despite modest lifestyles. The carbon emission categories differed between the two communities highlighting the need for an individualised approach to understanding the drivers of carbon emissions and mitigation responses.     

Assessment Of Noise Impacts At Airports

Airport operation is a major source of community concerns due to aircraft noise emissions particularly in locations close to airports and aircraft flight tracks. The effects of aircraft noise on humans can cause hearing damage for people working at airports and speech and sleep interference which can develop into stress for nearby communities. As such, it becomes essential when locating and designing to expand airports to optimize flight paths in a way to reduce noise exposure to nearby communities. For this purpose, it is required to assess changes in noise levels resulting from new runway configurations, evaluate increased aircraft operation demand, new fleet mix, revised routings and airspace structures, alternative flight profiles, and modifications to other operational procedures. This paper presents a noise impact assessment for the proposed expansion at the Beirut International Airport, Lebanon. Field noise measurements were collected at sensitive noise receptors along selected locations around the airport and the corresponding airport traffic flow was characterized. A mathematical model was then applied to simulate noise levels as a function of the different airplane classes, operations, flight path, and landing characteristics. The model was also used to predict future noise levels, optimize airplane flight path, and assess mitigation measures to minimize potential aircraft noise impacts.     

A planning-oriented sustainability assessment framework for peri-urban water management in developing countries

DPSIR and the three-pillar model are well-established frameworks for sustainability assessment. This paper proposes a planning-oriented sustainability assessment framework (POSAF). It is informed by those frameworks but differs insofar as it puts more emphasis on a constructivist conception which recognises that sustainability needs to be defined anew for each planning problem. In finding such a consensus definition, POSAF uses participatory scenario analysis and participatory planning, technical feasibility study, participatory assessment, analysis of trade-offs and social networks in an unusual combination and for goals that differ from the original conceptions of these methods. POSAF was applied in a peri-urban area of Mexico City for the design of improved water service provision, integrating solid waste management. It supported consensus amongst users about the importance of environmental issues, informed planners about the values of stakeholders and users, detected local differences, and identified possible conflicts at an early stage of decision-making.     

减缓·适应——应对气候变化的若干规划议题思考

通过对气候变化与城市规划关 系的辨析,阐述了应对气候变化的规划内 涵,构建了应对气候变化的规划研究框 架。从能源利用、交通与土地使用、建筑 设计与管理、水资源管理、固废处理、旧 材料利用等方面提出了减缓气候变化的 若干规划议题;从温度变化、海平面上 升、降雨模式变化、热带风暴等方面提出 了适应气候变化的若干规划议题。提出 将应对气候变化规划与法定规划体系有 机整合,是当前城市规划行业急需解决 的问题。     

不良地质条件下CFG桩充盈系数超常的影响因素分析及改进措施

长螺旋钻机钻孔、管内泵压CFG混合料成桩的施工工艺,具有施工噪音低,成桩速度快、工程造价低等特点,特别在一些复杂地层和不良地质条件下的安全施工更起到了重要的作用。结合西成铁路客运专线户县东站路基地基处理CFG桩施工,对液化不良地质条件下施工CFG桩充盈系数超常的影响因素进行分析及制定改进措施,并对改进效果进行了数据对比分析,将充盈系数控制在合理范围内,既保证了成桩质量,又起到了经济效益和社会效益,为以后类似液化不良地质地基CFG桩的施工起到了很好的借鉴作用。     

Extracellular Vesicles from 50,000 Generation Clones of the Escherichia coli Long-Term Evolution Experiment

Extracellular vesicles (EVs) are critical elements of cell–cell communication. Here, we characterized the outer membrane vesicles (OMVs) released by specific clones of Escherichia coli isolated from the Long-Term Evolution Experiment after 50,000 generations (50K) of adaptation to glucose minimal medium. Compared with their ancestor, the evolved clones produce small OMVs but also larger ones which display variable amounts of both OmpA and LPS. Tracking ancestral, fluorescently labelled OMVs revealed that they fuse with both ancestral- and 50K-evolved cells, albeit in different proportions. We quantified that less than 2% of the cells from one 50K-evolved clone acquired the fluorescence delivered by OMVs from the ancestral strain but that one cell concomitantly fuses with several OMVs. Globally, our results showed that OMV production in E. coli is a phenotype that varies along bacterial evolution and question the contribution of OMVs-mediated interactions in bacterial adaptation.     

AI+智慧建筑研究

以当今全球第四次科技革命为宏观背景,以中国人工智能和建筑业国家战略为重要依据,综合基础理论、行业特色、产业化多维视角,提出“AI+智慧建筑”、“AI建筑”、“智慧建筑+AI”概念和产业链模型,提出采用产业链模型指导产业规划的方法。依据产业发展现状和未来3~5年发展趋势,总结提炼出AI+智慧建筑28个核心应用场景,重点介绍了建筑物故障诊断预测与健康管理和基于深度学习的智能视频分析理解。最后,对未来“AI+智慧建筑”的核心技术依赖进行剖析,给出产业重点发展方向建议。     

Assessment of the effectiveness of two heat removal techniques for permafrost protection

Two mitigation techniques, an air convection embankment and an embankment of a granular material with an integrated heat drain, have been tested for the implementation in the shoulders of road and airfield embankments in permafrost regions. Both techniques will allow cold air to penetrate the embankment from the bottom, while warm air is dissipated at the top. The techniques have been tested in the laboratory, where a small-scale embankment (SSE) was build and placed in a cold room to measure the embankment temperatures during winter conditions. A numerical modeling has been developed and calibrated on the SSE to verify the effects on the thermal regime of full-scale embankments. The results have shown that both techniques will cause a decrease in temperature, which will minimize or even possibly avoid permafrost degradation underneath the embankments. The laboratory results have also shown that the effectiveness of the air convection embankment technique can be increased during winter conditions by ventilating the top and the bottom of the embankment shoulders. Installation of air intakes along the shoulders will facilitate air flow into the system during winter and will trap the cold air in the bottom of the embankment through the summer period. This solution has been verified using the numerical model.