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关键词： BP Deepwater Horizon Explosion & Oil Spill, 2010   DEEP-sea ecology   ENVIRONMENTAL impact analysis   OIL wells -- Blowouts   FOOD chains (Ecology)   CARBON cycle (Biogeochemistry)  

摘要： Approximately 90% of the volume of the Gulf of Mexico is contained in water deeper than 200 m, a region where the Deepwater Horizon (DWH) blowout had more impact on ecosystems than any previous oil spill. The remoteness and relative inaccessibility of the deep sea makes documenting even acute impacts to the animals that live in this realm difficult. This article reviews Natural Resource Damage Assessment studies and follow-up work funded as part of the Gulf of Mexico Research Initiative that targeted deepwater pelagic and benthic fauna. Oil was incorporated into the pelagic food web, and a reduction in planktonic grazers led to phytoplankton blooms. Fish larvae were killed, and a generation may have been lost. Cetaceans were killed, and many avoided the area of the spill. In the benthic realm, there was a large loss of diversity of soft-bottom infauna, which were still not recovering a year after the DWH oil spill. Colonial octocorals that are anchored to the hard seafloor and are especially vulnerable to anthropogenic impact, died as a result of being covered with flocculent material containing oil and dispersant. Soft- and hard-bottom effects of the oil spill were found as much as 14 km away from the DWH wellhead site. Deep-sea communities in the Gulf of Mexico are diverse, play critical roles in the food web and carbon cycling, affect productivity, are sensitive to perturbations, and are at risk to contaminant exposure;thus, it is important to understand the effects on these natural resources.

摘要： The Deepwater Horizon (DWH) oil spill originated at the base of the continental shelf in the northern Gulf of Mexico (GoM), but large quantities of the oil were transported to the shelf (<= 200 m water depth) and into coastal waters (herein defined as <= 15 km from the coast). Water-column effects were generally limited to the period of the ongoing oil releases, although, due to an extensive oil sedimentation event ("dirty blizzard"), effects on the benthos have the potential to be chronic, especially in soft sediments. Impacts on phytoplankton, zooplankton, and ichthyoplankton were relatively short-lived, and the abundance and species composition of planktonic communities returned to pre-spill conditions within a year of the event. Mortalities of larval fish were generally less than 20% of Gulf-wide species populations owing to the extensive and extended spawning periods of most species. Impacts on the productivity of the region's fisheries were also relatively short-lived and influenced by extensive fishery closures to protect seafood safety, although long-term effects may eventually alter the productivity of some stocks. Benthic communities exhibited effects from the spill that ranged from negligible to significant. Hard-bottom communities, including natural and artificial reefs, suffered injuries that were severe and long lasting. Due to the patchy nature of oil deposition, high tolerance of toxins, and low bioavailability, effects on soft-sediment communities appear to be minimal except in areas, such as beaches, where oil settled in very high amounts. However, DWH oil may persist in coastal and continental shelf sediments for decades if it is sequestered by continuing sedimentation in the absence of events such as tropical storms that may resuspend contaminated bottom material. Nevertheless, vertebrates and shellfish foraging or living in the sediments may be continuously exposed to weathered DWH oil. Understanding the full impacts of the spill requires sustai

关键词： Deepwater Horizon oil spill   NRDA   Injury   Salt marsh   Louisiana  

摘要： The coastal Wetland vegetation component of the Deepwater Horizon oil spill Natural Resource Damage Assessment documented significant injury to the plant production and health of Louisiana salt marshes exposed to oiling. Specifically, marsh sites experiencing trace or greater vertical oiling of plant tissues displayed reductions in cover and peak standing crop relative to reference (no oiling), particularly in the marsh edge zone, for the majority of this four year study. Similarly, elevated chlorosis of plant tissue, as estimated by a vegetation health index, was detected for marsh sites with trace or greater vertical oiling in the first two years of the study. Key environmental factors, such as hydrologic regime, elevation, and soil characteristics, were generally similar across plant oiling classes (including reference), indicating that the observed injury to plant production and health was the result of plant oiling and not potential differences in environmental setting. Although fewer significant impacts to plant production and health were detected in the latter years of the study, this is due in part to decreased sample size occurring as a result of erosion (shoreline retreat) and resultant loss of plots, and should not be misconstrued as indicating full recovery of the ecosystem. (C) 2016 The Authors. Published by Elsevier Ltd.

关键词： nitrogen management   population growth   ecological fitness   Cry protein   arthropods   Oryza sativa   Poaceae   Cnaphalocrocis medinalis   Nilaparvatis lugens   Pirata subpiraticus   Cyrthorinus lividipennis   Lepidoptera   Hemiptera  

摘要： Nitrogen is a critical factor for plant development and nitrogen input is one of the important tactics to enhance the development and yield of crops. Nevertheless, nitrogen input could influence the occurrence of insects positively or negatively. Nitrogen is also one of the main elements composing the insecticidal crystal (Cry) protein. Cry protein production could affect nitrogen partitioning in Bt plants and as such nitrogen input may influence insect pest management in transgenic Bt rice, Oryza sativa L. (Poaceae). To test this possibility, we evaluated the impacts of nitrogen regimes on the main insect pests and their predators on two Bt rice lines, T2A-1 and T1C-19, expressing Cry2A and Cry1C, respectively, and their non-transgenic parental counterpart MH63. The results showed that Cry proteins with different nitrogen regimes have enough insecticidal activity on rice leaffolder, Cnaphalocrocis medinalis Guenee (Lepidoptera: Crambidae), in both laboratory and field experiments. Laboratory studies indicated that relevant parameters of ecological fitness in brown planthopper, Nilaparvata lugens (Stal) (Hemiptera: Delphacidae), a non-target insect pest, were significantly affected by nitrogen input both on Bt and MH63 rice lines. Nymphal survival, female adult longevity, and egg hatchability in N. lugens differed significantly among rice varieties. The experiments conducted in rice fields also demonstrated that nitrogen was positively correlated with the abundance of N. lugens on Bt rice, similar to that on MH63 rice. The abundances of two predators - the wolf spider Pirata subpiraticus (Boesenberg & Strand) (Araneae: Lycosidae) and the bug Cyrthorhinus lividipennis Reuter (Hemiptera: Miridae) - were significantly affected by rice growth stages but not by nitrogen input and rice varieties. In conclusion, the above results indicate that high nitrogen regimes for Bt rice (T2A-1 and T1C-19) and non-Bt rice (MH63) cannot facilitate the management of insect pests.

关键词： 牛从直流   共用接地极   单极金属回线  

摘要： 牛从直流为同塔双回共用接地极建设,一回单极金属与单极大地回线方式相互转换过程中存在接地极接入、站高速接地开关合上的短暂过程,若此时另一回为单极大地回线方式运行,则接地极电流将在转换回产生分流。分析了单极大地运行回线的接地极电流分流至另一回线的机理,梳理的了该分流电流对保护的影响,并提出了防范措施和建议。

关键词： 主成分分析   土地利用结构   驱动力  

摘要： 以2009—2013年的土地数据为基础,运用SPSS 22.0软件平台,采用主成分分析法,选取唐河县的GDP、人口数量结构、固定资产投资量等指标为驱动因子,分析驱动因子对土地利用变化的影响。并根据分析结果提出相应的建议,以提高唐河县的土地利用效率,进一步优化土地利用结构。

关键词： 蒙特卡罗   乳腺癌   电子线   角度变化  

摘要： 目的使用蒙特卡罗算法分析不同照射角度变化对乳腺癌患者术后电子线放疗计划剂量分布影响。方法使用MCNP5蒙特卡罗粒子输运软件包建立乳腺癌患者术后电子线照射模型,模拟电子线照射过程中350°、355°、5°、10°四个照射角度变化,计算靶区胸壁及敏感器官患侧肺、健侧肺、心脏的剂量分布,分析其剂量学特点。结果选取350°、355°、0°、5°、10°五个角度后,0°对照组胸壁接受剂量最高,355°组、350°组、10°组、5°组接受剂量依次降低;敏感器官的接受剂量在旋转角度模拟后均有升高,患侧肺和心脏靠近射野,接受剂量和变化程度均较大,0°对照组、350°组、355°组、10°组、5°组患侧肺接受剂量依次升高,0°对照组、355°组、350°、10°组、5°组组心脏和健侧肺接受剂量依次升高。结论本文使用蒙特卡罗算法对乳腺癌患者术后电子线放疗进行模拟研究,发现不同照射角度变化会降低靶区接受剂量,升高敏感器官接受剂量。

关键词： 地铁   地下车站   抗震设计   反应位移法  

摘要： 以武汉地铁某三层地下车站为例,采用抗震计算方法反应位移法进行抗震计算分析,介绍反应位移法基本原理,并详细阐述反应位移法所需的各参数和计算过程。通过对此车站的抗震计算分析,表明在6度抗震设防烈度下,结构按照正常使用状况配筋就能够满足抗震设防的要求,抗震工况对构件截面尺寸及配筋不起控制作用,此研究成果可应用于武汉地区地下车站结构的抗震设计中。

关键词： 位移法   反力法   混凝土框架   连续性倒塌   失效时间  

摘要： 本文采用了"位移法"和"反力法"对失柱的混凝土框架结构进行线性与非线性动力倒塌分析,并把位移法与反力法的分析结果进行对比,两者吻合较好,同时采用线性动力与非线性动力计算方法分别对具有相同平面布置不同高度的框架结构进行连续倒塌模拟分析,得到不同失效时间失效点的位移时程曲线。分析结果表明:柱的失效时间对位移法和反力法线性动力分析结果影响较小,随着失效时间的增大,结构的动力效应趋于收敛;柱的失效时间对位移法和反力法非线性动力分析结果影响较大,但是随着失效时间的增加,结构的动力效应趋于收敛。

关键词： 工作要求   冲动性人格   社会支持   离职倾向  

摘要： 基于压力交互理论与工作要求-资源模型,以932名制造业一线员工为研究对象,首先检验了制造业一线员工的工作要求对离职倾向的影响,进而考察了冲动性人格与社会支持对工作要求与离职倾向关系的链式调节作用。研究结果发现,制造业一线员工的工作要求对离职倾向具有正向影响;冲动性人格调节工作要求对离职倾向的影响;社会支持在冲动性人格对工作要求与离职倾向关系的调节效应中起部分中介作用,即冲动性人格通过影响社会支持进而调节工作要求与离职倾向间的关系。研究结论对于深入理解制造业员工的高离职率提供了一个新的理论视角。