Comparative study on performances of a heat-pipe PV/T system and a heat-pipe solar water heating system

The heat-pipe solar water heating (HP-SWH) system and the heat-pipe photovoltaic/thermal (HP-PV/T) system are two practical solar systems, both of which use heat pipes to transfer heat. By selecting appropriate working fluid of the heat-pipes, these systems can be used in the cold region without being frozen. However, performances of these two solar systems are different because the HP-PV/T system can simultaneously provide electricity and heat, whereas the HP-SWH system provides heat only. In order to understand these two systems, this work presents a mathematical model for each system to study their one-day and annual performances. One-day simulation results showed that the HP-SWH system obtained more thermal energy and total energy than the HP-PV/T system while the HP-PV/T system achieved higher exergy efficiency than the HP-SWH system. Annual simulation results indicated that the HP-SWH system can heat the water to the available temperature (45°C) solely by solar energy for more than 121 days per year in typical climate regions of China, Hong Kong, Lhasa, and Beijing, while the HP-PV/T system can only work for not more than 102 days. The HP-PV/T system, however, can provide an additional electricity output of 73.019 kWh/m², 129.472 kWh/m², and 90.309 kWh/m² per unit collector area in the three regions, respectively.     

Photovoltaic-thermal (PV/t) panel to minimize electrical and air conditioning energy consumption of a typical office in Beirut

A combined photovoltaic–thermal (PV/t) panel is proposed to produce simultaneously electricity and heat from one integrated unit. The unit utilizes effectively the solar energy through achieving higher PV electrical efficiency and using the thermal energy for heating applications. To predict the performance of the PV/t at a given environmental conditions, a transient mathematical model was developed. The model was integrated in a heating application for a typical office space in the city of Beirut to provide the office needs for electricity, heating during winter season, and dehumidification and evaporative cooling during the summer season. To minimize the yearly office energy (electrical and heat) needs, the PV/t panel cooling air flow rate and the dehumidification regeneration temperature were determined for opimal unit operation. Thermal energy savings of up to 85% in winter and 71% in summer were achived compared to conventional systems at a payback period of 8 years for the panels.     

太湖流域水环境保护目标责任考核机制研究

建立科学规范的环境保护目标责任考核机制是实现我国环境保护目标的重要手段之一。作为一个自上而下的制度典范,基层环境保护管理部门是环境管理目标的落实者也是被考核的对象。本研究以太湖流域水环境保护基层管理部门面临的水环境保护目标责任考核机制为研究对象,从水环境保护考核指标的设定、考核评价的实施以及考核结果的应用三个方面分析太湖流域水环境保护目标考核机制的实施现状。结果表明,现阶段的考核体系存在考核指标设置不合理、考核过程实施过程成本较高,以及考核结果缺乏对管理部门的激励性等问题。最后,本文从提高现阶段太湖流域水环境保护考核指标设定的科学性、协调不同部门之间的关系以及加强考核结果的公开与合理应用方面对太湖流域水环境保护目标责任考核机制提出了政策建议。     

Effects of humic acids derived from lignite and cattle manure on antioxidant enzymatic activities of barley root

To investigate the effects of humic acids (HAs) on the ability of plants to defend themselves against oxidative stress, barley was hydroponically cultured in the absence and presence of HAs, and the antioxidant enzymatic activities (catalase, superoxide dismutase, ascorbate and glutathione peroxidases) of root tissue were evaluated. Auxin-like structures in HAs, which were extracted from an oxidation product of lignite (LHA) and compost derived from cattle manure (CHA), were identified by pyrolysis-gas chromatography/mass spectrometry (GC/MS) with tetramethylammonium hydroxide. The LHA, which had the lower molecular weight, was more effective in promoting the growth of barley root than CHA. However, the amounts of auxin-like structures in the CHA were much higher than those for LHA. The antioxidant enzymatic activities were initially decreased in the presence of LHA and CHA at the first day after refreshing the culture solution, but were significantly increased on the second day. The CHA sample, which contained relatively high levels of phenolic acids that contained auxin-like structures, was effective in increasing four types of enzymatic activities, while the activities of catalase and ascorbate peroxidase were increased in the presence of LHA, which contains naphthalene derivatives. These results indicate that using HAs as a supplement can be effective in enhancing antioxidation enzymatic activities, while the appearance of the effects is retarded because of the decomposition and release of auxin-like compounds from HAs by organic acids from the plant roots.     

Determination of neonicotinoids in Estonian honey by liquid chromatography–electrospray mass spectrometry

The aim of the study was to provide a comprehensive overview of neonicotinoid pesticide residues in honey samples for a single country and compare the results with the import data for neonicotinoid pesticides. The levels of four neonicotinoid pesticides, namely thiamethoxam, imidacloprid, acetamiprid, and thiacloprid, were determined in 294 honey samples harvested from 2005 to 2013 from more than 200 locations in Estonia. For the analyzed honey samples, 27% contained thiacloprid, and its levels in all cases were below the maximum residue level set by the European Union. The other neonicotinoids were not detected. The proportion of thiacloprid-positive samples for different years correlates well with the data on thiacloprid imports into Estonia, indicating that honey contamination with neonicotinoids can be estimated based on the import data.     

Bison and cattle grazing management,bare ground coverage,and links to suspended sediment concentrations in grassland streams

This study quantified the impact of bison and cattle grazing management practices on bare ground coverage at the watershed, riparian, and forested riparian scales within the Flint Hills ecoregion in Kansas. We tested for correlations between bare ground coverage and fluvial suspended sediment concentrations during base‐flow and storm‐flow events. We used remotely sensed imagery combined with field surveys to classify ground cover and quantify the presence of bare ground. Base‐flow water samples were collected bi‐monthly during rain‐free periods and 24 h following precipitation events. Storm‐flow water samples were collected on the rising limb of the hydrograph, using single‐stage automatic samplers. Ungrazed treatments contained the lowest coverage of bare ground at the watershed, riparian, and forested riparian scales. Bison treatments contained the highest coverage of bare ground at the watershed scale, while high‐density cattle treatments contained the highest coverage of bare ground at the riparian and forested riparian scales. In bison and cattle‐grazed treatments, a majority of bare ground was located near fence lines, watershed boundaries, and third‐ and fourth‐order stream segments. Inorganic sediment concentrations at base flow were best predicted by riparian bare ground coverage, while storm‐flow sediment concentrations were best predicted by watershed scale bare ground coverage.     

Benchmarking Optical/Thermal Satellite Imagery for Estimating Evapotranspiration and Soil Moisture in Decision Support Tools

Generally, one expects evapotranspiration (ET) maps derived from optical/thermal Landsat and MODIS satellite imagery to improve decision support tools and lead to superior decisions regarding water resources management. However, there is lack of supportive evidence to accept or reject this expectation. We “benchmark” three existing hydrologic decision support tools with the following benchmarks: annual ET for the ET Toolbox developed by the United States Bureau of Reclamation, predicted rainfall‐runoff hydrographs for the Gridded Surface/Subsurface Hydrologic Analysis model developed by the U.S. Army Corps of Engineers, and the average annual groundwater recharge for the Distributed Parameter Watershed Model used by Daniel B. Stephens & Associates. The conclusion of this benchmark study is that the use of NASA/USGS optical/thermal satellite imagery can considerably improve hydrologic decision support tools compared to their traditional implementations. The benefits of improved decision making, resulting from more accurate results of hydrologic support systems using optical/thermal satellite imagery, should substantially exceed the costs for acquiring such imagery and implementing the remote sensing algorithms. In fact, the value of reduced error in estimating average annual groundwater recharge in the San Gabriel Mountains, California alone, in terms of value of water, may be as large as $1 billion, more than sufficient to pay for one new Landsat satellite.     

Governing sustainability: a dialogue between Local Agenda 21 and transition management

Since the 1990s, the local level of governance has become increasingly important in addressing the challenge of sustainable development. In this article, we compare two approaches that seek to address sustainability locally, namely Local Agenda 21 and transition management. Discussing both approaches along six dimensions (history, aim, kind of change, governance understanding, process methodologies, and actors), we formulate general insights into the governance of sustainability in cities, towns, and neighbourhoods. This dialogue illustrates two related modes of thinking about sustainability governance. We touch upon the importance of an integrated perspective on sustainability transitions through which sustainability is made meaningful locally in collaborative processes. We suggest that the explicit orientation towards radical change is a precondition for governing sustainability in a way that addresses the root causes of societal challenges. Governing sustainability should address the tensions between aiming for radical change and working with status quo-oriented actors and governing settings. We conclude that governing sustainability should be about finding creative ways for opening spaces for participation, change, and experimentation, that is, for creating alternative ideas, practices, and social relations. These spaces for innovation encourage a reflexive stance on ways of working and one's own roles and attitudes, thereby preparing a fertile terrain for actors to engage in change from different perspectives.     

Quality Control for Environmental Policy Appraisal Tools: An Empirical Investigation of Relations Between Quality,Quality Control and Effectiveness

The spectre of regulatory reform carried out in a range of Western countries has generated concern amongst parts of the environmental policy community. Quality and effectiveness are said to be at stake, but empirically there is a dearth of data on the relationship between provisions for quality control and the effects on quality and effectiveness. This research addresses this lacuna by analysing the effects of different quality control provisions in the Netherlands and Denmark for a globally institutionalized environmental appraisal tool—Environmental Assessment (EA). Extensive technical provisions for quality control in the Netherlands have led to it being described as the ‘Rolls Royce’ of EA systems, while in Denmark the polity is expected to take charge of quality control. The effects of quality control are investigated through surveys and in-depth interviews with actors centrally engaged with EA implementation. The results show that quality control provisions are poorly related to the perceived quality and effectiveness of EA. Only the appropriateness of the scope of EA reports is perceived to be strongly related to quality control provisions. The findings are relevant for environmental policy communities concerned with quality control systems and effectiveness of policy appraisal tools and policy-makers contemplating regulatory reforms.     

Environmental perceptions of second home tourism impacts in Finland

Experiencing nature and enjoying natural amenities have long been identified as key motives for rural second home tourism. However, the more people travel and spend time in the natural environment, the more it is disturbed by their actions and activities. In this paper, we examine how people perceive the environmental impacts of rural second home tourism and how they justify their views. The study focuses on Finland where rural second homes are widespread. Analysis is based on a questionnaire survey conducted among Finns in 2012 (n?=?1189). Responses from different groups of respondents (second home owners, regular users of second homes and non-users) are quantitatively and qualitatively analysed. The results indicate that the Finnish respondents generally think that second home tourism poses some degree of harmful environmental impacts. However, it is the second home owners who are least worried about these environmental impacts. They generally justify their opinions using a “place-related” perspective, that is, by referring to their own experiences and actions at the cottage site. In contrast, the non-users see environmental impacts more often from a broader perspective by referring to the wider environmental interconnections with second home tourism. In our discussion, we introduce the notions of place-based (relative) and phenomenon-based (relational) environmental perceptions as a potential framework for future research on this topic. In mitigating the increasing environmental impacts of second home tourism, understanding the environmental perceptions and awareness of second home owners and users is crucial to be successful in mobilising sustainable options and environmental governance.