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1.
浮游植物是水生态系统中最重要的组成部分,因其对水环境变化敏感而常被用于指示水环境状态,但其对环境的响应受分类方法的影响.为了解洞庭湖浮游植物种群(门、属)和功能群(FG)两种分类法对环境的驱动响应特征和适用性,于2019年3~12月分水期对该湖共进行了4次采样,比较分析了浮游植物种群和功能群的分布特征及其与环境因子的响应关系,并对比了TLI指数、 Shannon-Wiener指数、Q指数等评价方法在洞庭湖的适用性.结果表明,洞庭湖共检出浮游植物6门61属,可划分为23个功能群和9个优势功能群,功能群演替趋势为P/MP/D(3月)■月)■月)■(12月).层次分割结果表明,洞庭湖浮游植物的种群分布与变化受环境因子的驱动大于空间驱动;影响浮游植物种群和功能群的主要环境因子为水温(WT)、高锰酸盐指数、溶解氧(DO)、电导率(Cond)、水位(WL)和总磷(TP),环境因子对两者的独立解释性排序相差不大.RDA分析表明,浮游植物功能群对环境因子的响应要优于浮游植物种群.综合对比分析发现,利用Q指数进行水质评价在洞庭湖水体有较好的适用性.  相似文献   
2.
为定量评估生物炭对主粮作物产量的影响,收集了公开发表的116篇相关文献,共866对数据,采用Meta分析法定量分析了生物炭对我国主粮作物产量的影响及其影响因子,同时构建结构方程模型(SEM)进一步解释了因子间的交互关系.结果表明,与不施用生物炭相比,生物炭施用后可改善主粮田土壤理化性质,提高主粮作物产量,平均增产率为8.77%.其中,当生物炭pH为7~8时,平均增产率最大,可达26.49%;其C/N<60时,平均增产率为13.73%,显著高于C/N≥60的平均增产率.将生物炭施入酸性或中性土壤中,更能发挥其增产效应.当施炭量为10~20 t·hm-2时,小麦和玉米的平均增产率最大;施炭量为15~25 t·hm-2时,水稻平均增产率最大.但是,不同施炭水平的水稻增产率相近,可考虑损失部分产量,适当减施以兼顾经济效益.此外,生物炭增产效应会随施用年限增加而不断减弱,一般3 a后增产不显著.SEM表明生物炭施用量不仅直接影响主粮作物产量,还通过改善土壤肥力间接影响主粮作物产量,而生物炭C/N和pH仅通过改善土壤肥力影响主粮作物产量.因此,今后...  相似文献   
3.
Urbanization and mass movement of the population from rural areas and small cities to megacities have led to environmental, economic, and social problems in Iran. In dealing with these challenges, assessing resource and environmental carrying capacity (RECC) is considered an effective method to leverage space and capital to achieve sustainable development. This study aimed to rank the provincial RECC in Iran. Toward this purpose, environmental indices were generated from remotely sensed and statistical census data. Then, the provinces were scored in terms of environmental, economic, and infrastructural carrying capacities, and RECC using the mean variance analysis method. Results demonstrated that in most areas, there is no relationship between economic and infrastructural capacities and development. Statistically, a correlation coefficient of −0.53 between economic and environmental carrying capacities indicated excessive use of environmental capacities. Moreover, the spatial distribution pattern of environmental, economic, and infrastructural carrying capacity was entirely heterogeneous between the provinces; there was a northeast–southwest pattern in terms of infrastructural capacity and an economic pattern from north to south. The distribution pattern of RECC is most consistent with the environmental capacity, pointing at the high weight of the indicators of the RECC model. In conclusion, this research offers a new vision for policymakers and provides a theoretical and applicable framework for implementing sustainable strategies in land-use planning. It is recommended that the RECC concept and tools can be used not only for planning but also for measuring the efficiency of spatial development programs and establishing land balances in the region.  相似文献   
4.
Conservation practitioners, natural resource managers, and environmental stewards often seek out scientific contributions to inform decision-making. This body of science only becomes actionable when motivated by decision makers considering alternative courses of action. Many in the science community equate addressing stakeholder science needs with delivering actionable science. However, not all efforts to address science needs deliver actionable science, suggesting that the synonymous use of these two constructs (delivering actionable science and addressing science needs) is not trivial. This can be the case when such needs are conveyed by people who neglect decision makers responsible for articulating a priority management concern and for specifying how the anticipated scientific information will aid the decision-making process. We argue that the actors responsible for articulating these science needs and the process used to identify them are decisive factors in the ability to deliver actionable science, stressing the importance of examining the provenance and the determination of science needs. Guided by a desire to enhance communication and cross-literacy between scientists and decision makers, we identified categories of actors who may inappropriately declare science needs (e.g., applied scientists with and without regulatory affiliation, external influencers, reluctant decision makers, agents in place of decision makers, and boundary organization representatives). We also emphasize the importance of, and general approach to, undertaking needs assessments or gap analyses as a means to identify priority science needs. We conclude that basic stipulations to legitimize actionable science, such as the declaration of decisions of interest that motivate science needs and using a robust process to identify priority information gaps, are not always satisfied and require verification. To alleviate these shortcomings, we formulated practical suggestions for consideration by applied scientists, decision makers, research funding entities, and boundary organizations to help foster conditions that lead to science output being truly actionable.  相似文献   
5.
Sectorial approach for monitoring heavy metal pollution in rivers has failed to report realistic pollution status and associated ecological and human health risks. The increasing spread of heavy metals from different sources and emerging risks to human and environmental health call for reexamining heavy metal pollution monitoring frameworks. Also, the sources, spread, and load of heavy metals in the environment have changed significantly over time, requiring consequent modification in the monitoring frameworks. Therefore, studies on heavy metal monitoring in rivers conducted in the last decade were evaluated for experimental designs, research frameworks, and data presentations. Most studies (∼99%) (i) lacked inclusiveness of all environmental compartments; (ii) focused on “one pollutant – one/two compartment” or sometimes “one pollutant – one compartment – one effect” approach; and (iii) remained “data-rich but information poor.” An ecological approach with integrative system thinking is proposed to develop a holistic approach for monitoring river pollution. It is visualized that heavy metal monitoring, risk analyses, and water management must incorporate tracking pollutants in different environmental compartments of a river (water, sediment, and floodplain/bank soil) and consider correlating it with riverbank land use. The systems-based pollution monitoring and assessment studies will reveal the critical factors that drive heavy metals pollutant movement in ecosystems and associated potential risks to the environment, wildlife, and humans. Also, water quality and pollution indexing tools would help better communicate complex pollution data and associated risks among all stakeholders. Therefore, integrating systems approaches in scientific- and policy-based tools would help sustainably manage the health of rivers, wildlife, and humans.  相似文献   
6.
The radiant heat flux from a pool fire is frequently calculated using the solid flame model, where the flame envelope is approximated as a stationary cylinder whose surface emits thermal radiation at a constant rate. Radiant heat flux calculations using the solid flame model assume the target to be at a given elevation, typically at ground level, and to have an unobstructed view of the fire. The presence of obstacles (e.g., walls, buildings, etc.) or terrain features that would create shaded areas and provide shielding of a target from the fire is typically neglected in these calculations: this is a conservative approach, but it is not accurate. This paper presents a methodology to utilize the solid flame model to calculate the heat flux to a target while taking into account the presence of an obstruction between the target and the fire. The shielded solid flame method can quantitatively account for the presence of obstacles as a passive mitigation measure and allows project developers or designers to optimize their facility layout to meet safety requirements. The methodology presented in this paper uses the same correlations found in currently used solid flame models (e.g., LNGFIRE3), therefore, it remains consistent with current regulatory requirements for LNG facilities in the U.S.  相似文献   
7.
Atmospheric oxidizing capacity (AOC) is an essential driving force of troposphere chemistry and self-cleaning, but the definition of AOC and its quantitative representation remain uncertain. Driven by national demand for air pollution control in recent years, Chinese scholars have carried out studies on theories of atmospheric chemistry and have made considerable progress in AOC research. This paper will give a brief review of these developments. First, AOC indexes were established that represent apparent atmospheric oxidizing ability (AOIe) and potential atmospheric oxidizing ability (AOIp) based on aspects of macrothermodynamics and microdynamics, respectively. A closed study refined the quantitative contributions of heterogeneous chemistry to AOC in Beijing, and these AOC methods were further applied in Beijing-Tianjin-Hebei and key areas across the country. In addition, the detection of ground or vertical profiles for atmospheric OH·, HO2·, NO3· radicals and reservoir molecules can now be obtained with domestic instruments in diverse environments. Moreover, laboratory smoke chamber simulations revealed heterogeneous processes involving reactions of O3 and NO2, which are typical oxidants in the surface/interface atmosphere, and the evolutionary and budgetary implications of atmospheric oxidants reacting under multispecies, multiphase and multi-interface conditions were obtained. Finally, based on the GRAPES-CUACE adjoint model improved by Chinese scholars, simulations of key substances affecting atmospheric oxidation and secondary organic and inorganic aerosol formation have been optimized. Normalized numerical simulations of AOIe and AOIp were performed, and regional coordination of AOC was adjusted. An optimized plan for controlling O3 and PM2.5 was analyzed by scenario simulation.  相似文献   
8.
为得到地铁区间隧道竖井送风有效风量的无量纲计算模型,通过推导地铁区间隧道竖井送风有效风量的无量纲公式,并采用数值模拟方法明确竖井送风有效风量与火源功率、火源距离、阻塞比和竖井送风量之间的量化关系。结果表明:火源功率、火源距离与竖井送风有效风量之间不存在函数关系;阻塞比对竖井送风有效风量影响显著,随着阻塞比的增大,有效风量逐渐减小,单侧列车停靠时,无量纲有效风量Qe*与阻塞比β呈-1.08次方减小关系,两侧列车停靠时,无量纲有效风量Qe*与阻塞比β呈-0.22次方减小关系;有效风量随竖井送风风量的增大逐渐增大,且有效风量增大比例高于送风风量,单侧列车停靠时,无量纲有效风量与无量纲送风风量呈1.11次方增大关系,两侧列车停靠时,无量纲有效风量与无量纲送风风量呈1.07次方增大关系。  相似文献   
9.
1-Butyl-2,3-dimethylimidazolium nitrate ([Bmmim][NO3]), a kind of versatile and novel ionic liquids, is widely applied in the modern petrochemical industry. Nevertheless, its thermal hazard safety data at high temperature or thermal disturbance conditions are currently unavailable. Therefore, this study aimed to characterize the thermal risk of [Bmmim][NO3] through auto-ignition temperature measurements, flash point analysis, thermal gravimetric analysis/differential scanning calorimetry (TGA/DSC), TGA-Fourier transform infrared spectroscopy (TGA-FTIR) and thermal decomposition kinetics analysis. Additionally, [Bmmim][NO3] was examined using isothermal thermogravimetric analysis at different temperatures (220, 230, 240, 250, 260 and 270 °C). The experimental results show that the flash point of [Bmmim][NO3] is 305.70 ± 9.30 °C and the auto-ignition temperature is 341.00 ± 21.60 °C with an ignition delay time of 8.6 s. In addition, using the nitrogen atmosphere TGA data to calculate the activation energy according to the Friedman, Kissinger and Flynn-Wall-Ozawa methods, roughly the same results were obtained. Finally, TGA-FTIR results show that [Bmmim][NO3] produced acetylene, butane, butanol and carbon dioxide during the thermal decomposition process. This study could provide data support and some guidance for the thermal hazard assessment and safety control of [Bmmim][NO3] during its use and storage.  相似文献   
10.
Deployment in a crisis zone is a perilous undertaking. Little is known right now about how humanitarian workers relate social and professional goals to lived experiences of high-risk environments. In South Sudan, ranked as the most dangerous country globally for aid workers, 20 international humanitarian staff were interviewed to examine their sense of place, well-being, and vocation, using thematic and interpretative phenomenological analysis. Subjectivities of humanitarian space hinged upon negotiating physical hardships and social relationships: Juba, the capital, was described as a ‘prison’ and a ‘party hotspot’. For expatriate staff, making sense of spatial, social, and professional transience was sharply gendered and rooted in the subjectivities of risk-taking, crisis management, and career-building. Two policy measures are highlighted here to address the implications of transience for human well-being and organisational effectiveness. Efforts to support teams and structure work environments, altering the humanitarian and vocational bubble, will help to develop resilience at the heart of humanitarian systems.  相似文献   
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