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871.
将安全系统工程理论应用于弹药减压式烧毁安全评价,通过分析影响安全水平的处废环境、防护环境等因素,建立了弹药减压式烧毁安全事故树,确定其危险因素并对其重要度进行了分析,据此从烧毁场地选择、作业过程中的安全规程等方面提出了相应的安全措施。  相似文献   
872.
中国目前生态环境形势严峻,环境管理体制存在诸多问题。通过分析这些问题,政府在环境管理中的职责和重要性随即体现出来,而一些相应的建议也即被提出。生态保护和环境建设是政府义不容辞的责任。只有依靠政府的领导,加快环境管理体制的完善,才能更好地解决中国严峻的生态环境问题。  相似文献   
873.
南昌市区地下浅部广泛分布有第四系砂砾石孔隙地下水,水量丰富,大部分地方水质较好,地下水的这些性质符合地下水水源热泵系统用水水源的要求。近年来南昌市区地下水地源热泵系统已陆续使用,但经验较少,回灌技术不成熟,监测和管理工作尚不到位和完善,现阶段热泵系统应以局部试用为好,在试用中做好与热泵系统使用有关的水文地质勘察和水资源论证、地下水回灌、热泵用水和地下水定期监测以及地下水地源热泵系统行政管理等各项工作,逐渐积累经验,使今后热泵系统使用地下水真正做到高效、安全和环保。  相似文献   
874.
为科学把握新疆维吾尔自治区区域创新系统的演进脉络和规律,将新疆区域创新系统40余年的发展历程划分为萌芽、过渡、构建与完善4个阶段,从环境要素、创新主体、企业创新、结网程度4个方面对各阶段进行盘点总结,分析推动区域创新系统发展的动力因素,总结出新疆区域创新系统发展的1个核心与4条历史主线,并得出两点基本经验:一是政府核心科技政策的实时引导与政策创新始终是系统发展的重要牵引力;二是系统的开放与市场化的深入始终为新疆区域创新系统发展的源动力。  相似文献   
875.
淡水系统中4种塑料颗粒的老化过程及DOC产物分析   总被引:5,自引:5,他引:0  
李婉逸  刘智临  苗令占  侯俊 《环境科学》2021,42(8):3829-3836
淡水系统中的微塑料污染及其生态效应已经引起国内外学者的广泛关注,但关于不同类型微塑料在自然环境中的老化研究较少.为探究不同类型微塑料的老化过程,分析老化产物,以4种水体中常见的微塑料聚丙乙烯(polystyrene,PS)、低密度聚乙烯(low-density polyethylene,LDPE)、聚丙烯(polypropylene,PP)和聚羟基丁酸(polyhydroxybutyrate,PHB)为研究对象,进行了40 d的自然光老化实验.结果表明:①在老化过程中,4种不同类型塑料老化析出液水质指标pH、ORP、EC和DO均产生不同程度的上升或下降趋势.②经扫描电镜(scanning electron microscope,SEM)观测发现LDPE表面形态变化最大,已经形成裂纹和孔洞.傅立叶红外检测发现,实验中LDPE的羰基指数增加程度最大,增加了31.48%.③微塑料老化会产生溶解态产物,即溶解性有机碳(dissolved organic carbon,DOC),DOC质量浓度随老化时间增加而增加,与本底值相比,老化40 d的PHB、PP和LDPE微塑料析出液中DOC质量浓度增加显著,分别增加了61.29%、69.49%和89.15%.以上结果表明经自然光照射,塑料会在自然水体中出现明显的老化,并释放出有机物,由此带来的生态效应应受到更多的关注和研究.  相似文献   
876.
At high densities, land uses get close enough to each other to support walk, bike, and transit modes above 60% of total trips. The San Francisco Bay Area census was used to define five density levels: rural, exurban, suburban, central city, and urban core. The urban core definition, over 50 persons per neighborhood acre, is much denser than in other research. The California Household Transportation Survey supplied new data on block group area, population, trip stages, trip distances, trip time, and travel mode by density. The National Household Transportation Survey supplied block group population, density, travel mode, and income data. Both sources show a strong nonlinear relationship going from rural to urban core: auto miles and trips decrease as walk and transit miles and trips increase. With density, people travel fewer miles and spend less time traveling. High-income households in dense areas travel far fewer miles than those living at higher densities. With sufficient density, complementary features play a role in furthering mode shift. For planning purposes, the need for parking greatly declines. The findings are a basis for similar research elsewhere on high densities and complementary features.  相似文献   
877.
Recovery and conservation of threatened species require adequate institutional responses. We tested an approach to systematically identify and measure how an institutional framework acknowledges threats and required responses for the recovery of endangered species. We measured institutional functional fit with a drivers-pressure-state-impacts-response (DPSIR) model integrated with a quantitative text mining method and qualitative analysis of statutory instruments to examine regulatory responses that support the recovery of 2 endangered species native to Australia, the bridled nailtail wallaby (Onychogalea fraenata) and the Eastern Bristlebird (Dasyornis brachypterus). The key components of the DPSIR model were present in the institutional framework at statutory and operational levels, but some institutional gaps remained in the protection and recovery of the Eastern Bristlebird, including feral predator control, weed control, and grazing management in some locations. However, regulatory frameworks varied in their geographic scope and the application and implementation of many instruments remained optional. Quantitative text mining can be used to quickly navigate a large volume of regulatory documents, but challenges remain in selection of terms, queries of co-occurrence, and interpretation of word frequency counts. To inform policy, we recommend that quantitative assessments of institutional fit be complemented with qualitative analysis and interpreted in light of the sociopolitical and institutional context.  相似文献   
878.
Advanced closed chamber system was used to study the fate of phenanthrene (3-rings PAHs) in the presence of linear alkylbenzene sulphonates (LAS). The results showed mineralization and metabolism of phenanthrene are fast in the “culture solution-lava-plant-air“ model ecological system. The distribution proportions of applied ^14C-activity in this simulative ecological system were 41%-45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO2. Main parts of the applied ^14C-activity exist in two forms, one is polar metabolites(25%) which mainly distribute in the root(23%),the other is unextractable part (23%) which have been constructed into plant root (8.98%), shoot (0.53%) or bonded to lava(13.2%). The main metabolites of phenanthrene were polar compounels (25% of applied ^14C-activity), and small portion of ^14C-activity was identified as non-polar metabolites(6% of applied ^14C-activity) and apparent phenanthrene(1.91% of applied ^14C-activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of ^14C-activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO2 at the concentration of 200 mg/L.  相似文献   
879.
Abstract:  Amphibians worldwide are facing rapid declines due to habitat loss and fragmentation, disease, and other causes. Where habitat alteration is implicated, there is a need for spatially explicit conservation plans. Models built with geographic information systems (GIS) are frequently used to inform such planning. We explored the potential for using GIS models of functional landscape connectivity as a reliable proxy for genetically derived measures of population isolation. We used genetic assignment tests to characterize isolation of marbled salamander populations and evaluated whether the relative amount of modified habitat around breeding ponds was a reliable indicator of population isolation. Using a resampling analysis, we determined whether certain land-cover variables consistently described population isolation. We randomly drew half the data for model building and tested the performance of the best models on the other half 100 times. Deciduous forest was consistently associated with lower levels of population isolation, whereas salamander populations in regions of agriculture and anthropogenic development were more isolated. Models that included these variables and pond size explained 65–70% of variation in genetically inferred isolation across sites. The resampling analysis confirmed that these habitat variables were consistently good predictors of isolation. Used judiciously, simple GIS models with key land-cover variables can be used to estimate population isolation if field sampling and genetic analysis are not possible.  相似文献   
880.
以赤子爱胜蚓(Eisenia fetida)为研究对象,根据OECD指南中的滤纸接触法和人工土壤法研究了四溴双酚A(TBBPA)的急性毒性和对蚯蚓体内抗氧化防御系统酶的影响.结果表明,滤纸接触法和人工土壤法检测TBBPA对蚯蚓的半致死浓度LC50分别为4.90mg·L-(148h)和16.7mg·kg-(114d),TBBPA对蚯蚓具有低等毒性.当TBBPA的浓度在0.05和0.1mg·kg-1时对蚯蚓超氧化物歧化酶(SOD)产生显著诱导;在0.05mg·kg-1时,对过氧化氢酶(CAT)和谷胱甘肽硫转移酶(GST)也产生显著诱导;脂质过氧化产物丙二醛(MDA)随TBBPA浓度的升高逐渐增加,呈良好的剂量效应关系(R2=0.97,p<0.01).SOD、CAT、GST和MDA可以作为土壤生态早期预警中潜在的敏感的生物标志物.  相似文献   
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