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991.
新能源汽车替代传统燃油车是减缓能源与环境压力并如期实现“双碳”目标的重要途径,但在重型车辆、工程车等领域推广较为缓慢.深圳市自2019年开始推广使用纯电动泥头车,并计划到2025年新能源环卫、泥头车数量达到8000辆.为深入探究纯电动泥头车替代柴油泥头车所产生的减污降碳协同效益,本研究基于一手调研数据,采用生命周期评价方法并结合GREET模型,对比分析了两类泥头车在燃料周期、车辆周期和配套设施周期3个周期内的能耗、主要空气污染物及碳排放情况.结果表明,纯电动泥头车全生命周期内能耗较柴油泥头车可减少36.2%,主要污染物如NOx、SO2、VOC和PM2.5降幅分别达81.3%、37.8%、29.0%和25.9%;温室气体(GHGs)排放强度减少14.4%,基准情境下2030年和2050年推广纯电动泥头车GHGs累计减排量分别为71.4万t和258.5万t.尽管节能减排效果显著,但其初始购置和售后维保成本过高是制约其推广的最主要因素,通过降低车辆及电池生产制造成本、提高充换电设施数量及售后维保能力等有望加快泥头车纯电动化.  相似文献   
992.
核心指标纵向层级传导作为市级国土空间规划的关键内容,对市域国土空间格局优化及规划统筹具有重要意义。针对当前指标传导研究不充分、不精细等问题,遵循“核心传导指标选择→指标传导技术逻辑构建→情景模拟预测”的研究思路,以常德市为例研究其2035年国土空间规划“市→县(区)”的核心指标传导。结果表明:(1)基于“指标全域总量预测—指标空间布局模拟—指标分区分类传导”的传导技术逻辑,通过SD与GeoSOS-FLUS模型的耦合集成利用,可有效实现市级国土空间规划核心指标“自上而下”与“自下而上”相结合的科学传导。(2)构建“人—地—业”协调的常德市国土空间利用SD模型,预测获得2035年市域核心指标总量,相应国土利用综合效益达12994.25亿元,相比2018年提升207.75%。(3)从指标传导结果来看,2035年常德市各县(市、区)社会经济类指标除常住人口规模指标外均保持增长趋势,边界类指标实现“只增不减”,用地类指标变化各异,但总体契合常德市主体功能区建设方向,核心指标传导结果符合实际。  相似文献   
993.
张杨  杨洋  江平  邓红蒂  祁帆  李强  常献伟  程鹏 《自然资源学报》2022,37(11):3005-3018
山水林田湖草生命共同体是对人与自然和谐统一关系的新认知,是生态文明理论的重要组成部分。以建立一个山水林田湖草生命共同体的研究范式为目的,系统剖析了山水林田湖草生命共同体理论与应用在基础探索、快速发展和多元繁荣三个阶段的研究重点与特征;再次审视了山水林田湖草生命共同体的内涵、阐明了概念新认知、基本特征、人与生命共同体关系;最后提出面向山水林田湖草生命共同体的“问题—目标—时空策略—目的”的实施路径,及构建以自然资源监测监管体系、自然资源资产产权体系、国土空间规划体系、国土空间用途管制体系、国土空间生态修复体系、法律法规体系等为主的制度体系,进而提升其科学性和实用性,为构建国土空间治理体系及治理能力现代化提供决策支撑。  相似文献   
994.
Abstract: Conservation and restoration goals are often defined by historical baseline conditions that occurred prior to a particular period of human disturbance, such as European settlement in North America. Nevertheless, if ecosystems were heavily influenced by native peoples prior to European settlement, conservation efforts may require active management rather than simple removal of or reductions in recent forms of disturbance. We used pre‐European settlement land survey records (1859–1874) and contemporary vegetation surveys to assess changes over the past 150 years in tree species and habitat composition, forest density, and tree size structure on southern Vancouver Island and Saltspring Island, British Columbia, Canada. Several lines of evidence support the hypothesis that frequent historical burning by native peoples, and subsequent fire suppression, have played dominant roles in shaping this landscape. First, the relative frequency of fire‐sensitive species (e.g., cedar [Thuja plicata]) has increased, whereas fire‐tolerant species (e.g., Douglas‐fir [Pseudotsuga menziesii]) have decreased. Tree density has increased 2‐fold, and the proportion of the landscape in forest has greatly increased at the expense of open habitats (plains, savannas), which today contain most of the region's threatened species. Finally, the frequency distribution of tree size has shifted from unimodal to monotonically decreasing, which suggests removal of an important barrier to tree recruitment. In addition, although most of the open habitats are associated with Garry oak (Quercus garryana) at present, most of the open habitats prior to European settlement were associated with Douglas‐fir, which suggests that the current focus on Garry oak as a flagship for the many rare species in savannas may be misguided. Overall, our results indicate that the maintenance and restoration of open habitats will require active management and that historical records can provide critical guidance to such efforts.  相似文献   
995.
Insects that should be considered for conservation attention are often overlooked because of a lack of data. The detailed information necessary to assess population growth, decline, and maximum range is particularly difficult to acquire for rare and cryptic species. Many of these difficulties can be overcome with the use of life table analyses and heat energy accumulation models common in agriculture. The wekiu bug (Nysius wekiuicola), endemic to the summit of one volcanic mountain in Hawaii, is a rare insect living in an environmentally sensitive alpine stone desert, where field‐based population assessments would be inefficient or potentially detrimental to natural and cultural resources. We conducted laboratory experiments with the insects by manipulating rearing temperatures of laboratory colonies and made detailed observations of habitat conditions to develop life tables representing population growth parameters and environmental models for wekiu bug phenology and demographic change. Wekiu bugs developed at temperatures only found in its environment on sunny days and required the thermal buffer found on cinder cones for growth and population increase. Wekiu bugs required approximately 3.5 months to complete one generation. The bug developed optimally from 26 to 30 °C, temperatures that are much higher than the air temperature attains in its elevational range. The developmental temperature range of the species confirmed a physiological reason why the wekiu bug is only found on cinder cones. This physiology information can help guide population monitoring and inform habitat restoration and conservation. The wekiu bug was a candidate for listing under the U.S. Endangered Species Act, and the developmental parameters we quantified were used to determine the species would not be listed as endangered or threatened. The use of developmental threshold experiments, life table analyses, and degree day modeling can directly inform otherwise unobservable habitat needs and demographic characteristics of extremely rare insects. Aplicación de Análisis Demográfico de Desarrollo Agrícola para la Conservación del Insecto Weiku Alpino Hawaiano  相似文献   
996.
研究以EPPM模型作为理论框架,探讨恐惧诉求对危险驾驶行为(超速和不系安全带)态度和行为意向的作用。54名职业驾驶员在观看交通安全恐惧诉求录像后,完成安全驾驶行为问卷。回归分析表明恐惧诉求的交通事故录像能够改变驾驶员对超速及不系安全带驾驶的态度和行为意向,但作用不完全一致。恐惧情绪唤起通过恐惧情感所引发的威胁评估过程中介对不超速行为意向的影响。最后,对研究的局限和未来的研究进行讨论。  相似文献   
997.
Growing or shrinking cities can experience increases in vacant land. As urban populations and boundaries fluctuate, holes can open in once tight urban areas. Many cities chase growth-oriented approaches to dealing with vacancies. It is critical to understand land-use alteration to accurately predict transformations of physical change in order to make better informed decisions about this phenomenon. This research utilizes the land transformation model (LTM), an artificial neural networking mechanism in Geographic Information Systems, to forecast vacant land. Variable influence on vacant land prediction and accuracy of the LTM is assessed by comparing input factors and patterns, using time-series data from 1990 to 2010 in Fort Worth, Texas, USA. Results indicate that the LTM can be useful in simulating vacant land-use changes but more precise mechanisms are necessary to increase accuracy. This will allow for more proactive decisions to better regulate the process of urban decline and regeneration.  相似文献   
998.
Using water curtain system to forced mitigate ammonia vapor cloud has been proven to be an effective measure. Currently, no engineering guidelines for designing an effective water curtain system are available, due to lack of understanding of complex interactions between ammonia vapor cloud and water droplets, especially the understanding of ammonia absorption into water droplets. This paper presents numerical calculations to reproduce the continuous ammonia release dispersion with and without the mitigating influence of a downwind water curtain using computational fluid dynamic (CFD) software ANSYS Fluent 14.0. The turbulence models kɛ and RNG were used to simulate the ammonia cloud dispersion without downwind water curtain. The simulated results were compared with literature using the statistical performance indicators. The RNG model represents better agreement with the experimental data and the kɛ model generates a slightly lesser result. The RNG model coupled with Lagrangian discrete phase model (DPM) was used to simulate the dilution effectiveness of the water curtain system. The ammonia absorption was taken into account by means of user-defined functions (UDF). The simulated effectiveness of water curtains has good agreements with the experimental results. The effectiveness of water mitigation system with and without the ammonia absorption was compared. The results display that the effectiveness mainly depends on the strong air entrainment enhanced by water droplets movement and the ammonia absorption also enhances the effectiveness of water curtain mitigation system. The study indicates that the CFD code can be satisfactorily applied in design criteria for an effective mitigation system.  相似文献   
999.
We examined the influence of several hydrological and meteorological parameters on the migratory movements of ayu Plecoglossus altivelis altivelis in central Japan. When comprehensively evaluating rivers and ayu behaviour on a catchment scale, the subjects of analysis typically include human activities and hydrological and meteorological phenomena. However, limiting analyses to such factors may be too restrictive when human activities are being conducted. Accordingly, we incorporated a biological viewpoint into the evaluation method, analysing hydrological data (river discharge, river water temperature, sea water temperature) to determine watershed characteristics and examining the relationship between these characteristics and the habitat conditions of ayu. Then we constructed a numerical model for ayu migratory runs that incorporated ayu ecology and watershed characteristics. Analyses of ayu movements from a lower estuarine dam demonstrated that downstream displacements were associated with high water flows of more than 200 m3 s−1 at the beginning of summer. We conclude that it is important to consider the effects of environmental parameters on the movements of different fish species to understand the causes of spatial variation in fish distribution in lowland rivers.  相似文献   
1000.
This study aimed to determine the toxicity of three organophosphorous pesticides, chlorpyrifos, terbufos and methamidophos, to three indigenous algal species isolated from local rivers and algal mixtures. The diatom Nitzschia sp. (0.30–1.68 mg L?1 of EC50 -the estimated concentration related to a 50% growth reduction) and the cyanobacteria Oscillatoria sp. (EC50 of 0.33–7.99 mg L?1) were sensitive to single pesticide treatment and the chlorophyta Chlorella sp. was the most tolerant (EC50 of 1.29–41.16 mg L?1). In treatment with the mixture of three pesticides, Chlorella sp. became the most sensitive alga. The antagonistic joint toxic effects on three indigenous algae and algal mixtures were found for most of the two pesticide mixtures. The results suggested that mixture of pesticides might induce the detoxification mechanisms more easily than the single pesticide. The synergistic interactions between terbufos and methamidophos to algal mixtures and between methamidophos and chlorpyrifos to Nitzschia sp. indicated methamidophos might act as a potential synergist. Differential sensitivity of three families of algae to these pesticides might result in changes in the algal community structures after river water has been contaminated with different pesticides, posing great ecological risk on the structure and functioning of the aquatic ecosystem.  相似文献   
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