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91.
92.
2013年青岛输油管道爆炸,大量石油污染了附近海岸。课题组采集了污染的沉积物样品,以原油为唯一碳源和能源,富集了四个石油降解菌群。生物多样性和群落分析表明,Luteibacter、Parvibaculum 和属于食烷菌科的一个属是降解菌群的主要优势菌,都属于变形菌门。从石油降解菌群中分离筛选,获得了9株具有不同16S rRNA基因序列的降解菌,分别属于8个属。重量法测定降解菌的石油降解率,其中5株的石油降解率大于30%。GC-MS分析结果表明,石油降解菌多倾向于降解烷烃,对多环芳烃的降解能力较差,其中5株细菌的烷烃降解率较大,仅1株菌D2对多环芳烃的降解率较大,其降解率在34.9%到77.5%。通过对高通量数据的分析,表明食烷菌属是菌群A和菌群E的主要降解菌群,其中筛选获得的菌株E4可能是菌群E的一株优势降解菌。本研究所筛选菌株证明了其石油降解潜力,为油污染海滩生物修复提供了菌株资源。  相似文献   
93.
The extraction of partition lines for long and narrow patches (LN patches) is an important yet difficult problem in the generalization of thematic data. When current methods are used to process polygons with irregular shapes or complex branch convergence zones, the extracted line structural features tend to be inaccurate and topologically erroneous. In this article, we propose an improved partition lines extraction algorithm of constrained Delaunay triangulation to counter these issues. The proposed method aims to maintain consistency between the extracted line structure characteristics and the actual object structure, especially for complex branch convergence zones. First, we describe three types of aggregation patterns (Type A, B, and C aggregation zones) that occur in partition line extractions for LN patches of complex branch convergence zones using Delaunay triangulation. Then, a partition line extraction algorithm that accounts for the direction between the edges of triangles and the distance of nodes in aggregation zones is proposed. Finally, we test our method for a dataset relating to Guizhou Province, China. Compared with the current method that uses quantitative indicators and visualization, the results indicate that our method not only has applicability for simple situations but also is superior for preserving structural features of complex branch convergence zones.  相似文献   
94.
Climate change has fundamentally altered the water cycle in tropical islands, which is a critical driver of freshwater ecosystems. To examine how changes in streamflow regime have impacted habitat quality for native migratory aquatic species, we present a 50‐year (1967–2016) analysis of hydrologic records in 23 unregulated streams across the five largest Hawaiian Islands. For each stream, flow was separated into direct run‐off and baseflow and high‐ and low‐flow statistics (i.e., Q10 and Q90) with ecologically important hydrologic indices (e.g., frequency of flooding and low flow duration) derived. Using Mann–Kendall tests with a running trend analysis, we determined the persistence of streamflow trends through time. We analysed native stream fauna from ~400 sites, sampled from 1992 to 2007, to assess species richness among islands and streams. Declines in streamflow metrics indicated a general drying across the islands. In particular, significant declines in low flow conditions (baseflows), were experienced in 57% of streams, compared with a significant decline in storm flow conditions for 22% of streams. The running trend analysis indicated that many of the significant downward trends were not persistent through time but were only significant if recent decades (1987–2016) were included, with an average decline in baseflow and run‐off of 10.90% and 8.28% per decade, respectively. Streams that supported higher native species diversity were associated with moderate discharge and baseflow index, short duration of low flows, and negligible downward trends in flow. A significant decline in dry season flows (May–October) has led to an increase in the number of no‐flow days in drier areas, indicating that more streams may become intermittent, which has important implications for mauka to makai (mountain to ocean) hydrological connectivity and management of Hawai'i's native migratory freshwater fauna.  相似文献   
95.
In this paper, an enhanced backtracking search algorithm (so-called MBSA-LS) for parameter identification is proposed with two modifications: (a) modifying the mutation of original backtracking search algorithm (BSA) considering the contribution of current best individual for accelerating convergence speed and (b) novelly incorporating an efficient differential evolution (DE) as local search for improving the quality of population. The proposed MBSA-LS is first validated with better performance than the original BSA and some other typical state-of-the-art optimization algorithms on a benchmark of soil parameter identification in terms of effectiveness, efficiency, and robustness. Then, the efficiency of the MBSA-LS is further illustrated by two representative cases: identifying soil parameters from both laboratory tests and field measurements. All comparisons demonstrate that the proposed MBSA-LS algorithm can give accurate results in a short time. Finally, to conveniently solve the problems of parameter identification, a practical tool ErosOpt for parameter identification is developed by integrating the proposed MBSA-LS and some other efficient algorithms for readers to conduct the parameter identification using optimisation algorithms.  相似文献   
96.
Previous studies have shown that shallow groundwater in arid regions is often not in equilibrium with near‐surface boundary conditions due to human activities and climate change. This is especially the case where the unsaturated zone is thick and recharge rate is limited. Under this nonequilibrium condition, the unsaturated zone solute profile plays an important role in estimating recent diffuse recharge in arid environments. This paper combines evaluation of the thick unsaturated zone with the saturated zone to investigate the groundwater recharge of a grassland in the arid western Ordos Basin, NW China, using the soil chloride profiles and multiple tracers (2H, 18O, 13C, 14C, and water chemistry) of groundwater. Whereas conventional water balance and Darcy flux measurements usually involve large errors in recharge estimations for arid areas, chloride mass balance has been widely and generally successfully used. The results show that the present diffuse recharge beneath the grassland is 0.11–0.32 mm/year, based on the chloride mass balance of seven soil profiles. The chloride accumulation age is approximately 2,500 years at a depth of 13 m in the unsaturated zone. The average Cl content in soil moisture in the upper 13 m of the unsaturated zone ranges from 2,842 to 7,856 mg/L, whereas the shallow groundwater Cl content ranges from 95 to 351 mg/L. The corrected 14C age of shallow groundwater ranges from 4,327 to 29,708 years. Stable isotopes show that the shallow groundwater is unrelated to modern precipitation. The shallow groundwater was recharged during the cold and wet phases of the Late Pleistocene and Holocene humid phase based on palaeoclimate, and consequently, the groundwater resources are nonrenewable. Due to the limited recharge rate and thick unsaturated zone, the present shallow groundwater has not been in hydraulic equilibrium with near‐surface boundary conditions in the past 2,500 years.  相似文献   
97.
The system with one floating rectangular body on the free surface and one submerged rectangular body has been applied to a wave energy conversion device in water of finite depth. The radiation problem by this device on a plane incident wave is solved by the use of an eigenfunction expansion method, and a new analytical expression for the radiation velocity potential is obtained. The wave excitation force is calculated via the known incident wave potential and the radiation potential with a theorem of Haskind employed. To verify the correctness of this method, an example is computed respectively through the bound element method and analytical method. Results show that two numerical methods. are in good agreement, which shows that the present method is applicable. In addition, the trends of hydrodynamic coefficients and wave force are analyzed under different conditions by use of the present analytical method.  相似文献   
98.
99.
刘寅  邹晓蕾 《气象学报》2016,74(1):1-17
随着卫星探测技术的进步、天气学和气候学理论的不断完善,以及高性能计算机广泛应用,卫星臭氧资料的种类得到极大丰富并被应用到多个研究领域中,取得了一系列重要成果。文中介绍了主要星载臭氧探测仪的发展概况,回顾了卫星臭氧资料在气象领域的应用研究成果,主要包括卫星臭氧资料在气旋或低压过程中、全球或区域臭氧的气候分布及变化特征、高原臭氧分布及变化特点、数值应用等方面的应用研究,并展望了卫星臭氧资料研究的未来发展趋势。   相似文献   
100.
国家级格点化定量降水预报系统   总被引:10,自引:7,他引:3  
曹勇  刘凑华  宗志平  谌芸  代刊  陈涛  杨寅 《气象》2016,42(12):1476-1482
利用主客观融合降水反演、降水统计降尺度、降水时间拆分等技术构建了国家级格点化定量降水预报系统。该系统结构合理,模块功能明确,于2014年6月在国家气象中心投入业务使用,生成0~168 h时效,10 km分辨率,逐3 h的格点化定量降水预报产品。通过对2015年第13号热带气旋苏迪罗的格点化降水预报个例检验,结果显示,相比欧洲中期数值预报中心的确定性模式预报和预报员主观预报,该产品能更好地体现台风降水的时空精细化分布特点,对福建东北部和浙江东南部的特大暴雨中心位置表现更准确细致。通过对2015年4—9月的格点化产品整体效果检验,结果显示,相比欧洲中期数值预报中心的确定性模式预报和由反距离客观分析后的预报员主观预报,该产品既能保持和预报员主观预报相同的准确率,同时也能较明显地提高降水预报的时空精细化程度。  相似文献   
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