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991.
高温热浪已成为世界范围内夏季频繁发生的极端气象灾害事件,威胁着人类健康。研究高温热浪人群健康风险的空间格局,可以识别灾害高风险区域,有助于预防和应对高温热浪灾害。本文以厦门市为例,在历史气象数据分析的基础上,建立了高温热浪案例库,分析了厦门高温热浪的基本特征。通过结合卫星遥感影像和人口统计数据,选取2010年的一次高温热浪事件,进行人口因子和环境因子叠加分析,研究了厦门市高温热浪人群健康风险的空间格局,得出如下结论:(1)厦门市高温热浪强度较轻,频率较高,偶尔会发生强等级高温热浪;(2)高温热浪人群健康的高风险区域集中在厦门本岛内,沿东北-西南方向呈带状分布,较高等级的风险热点主要位于湖里区江头街道的北部与东南部和思明区夏港街道大部分区域;(3)高温热浪人群健康风险的空间格局与环境和人口的空间分布特征密不可分。本文对完善国内高温热浪人群健康风险分析的科学体系具有重要意义。  相似文献   
992.
The smear zone, which develops during the placement of the prefabricated vertical drain (PVD) in the ground using a steel mandrel, is a significant factor that influences the performance of PVDs. The determination of the width and hydraulic conductivity of smear zone is an important consideration in designing ground improvement by preloading with PVDs. Thus, the extent and hydraulic conductivity of the PVD smear zone have received significant attention; however, there is still uncertainty and the topic remains discrepant among investigators. There is limited or no smear zone hydraulic conductivity data that is directly produced by laboratory or field tests. In this study, a laboratory smear zone model experiment that was developed as a performance test for determining the extent of the smear zone and measuring directly its hydraulic conductivity was used. Based on the findings obtained from two different materials (Craney Island dredgings and Hydrite R kaolinite soil), it is indicated that the disturbed zone is made up of two areas, namely smear zone and transition zone, and that the hydraulic conductivity in these areas is lower than the undisturbed soil. The ratio of the hydraulic conductivity of the smear and transition zones to that of the undisturbed soil was found to vary between 0.32 and 0.50 and between 0.57 and 0.82, respectively in different soils. The diameter of the smear zone was found to be 2.3–3.3 times higher than the equivalent diameter of the mandrel depending on the soil. The diameter of the transition zone extended 5.2–7.3 times the equivalent diameter of mandrel again depending on the soil. These directly measured values, in general, are supportive of the published values based on indirect means and the test device can be used to study the impact of mandrels of different size and shape and other factors by minor modification.  相似文献   
993.
香港西贡粮船湾组火山岩石柱区次生节理研究   总被引:2,自引:0,他引:2  
在香港世界地质公园西贡火山岩区,白垩纪粮船湾组发育有目前世界已知面积最大的流纹质碎斑熔岩石柱群。在详细的野外地质调查基础上,对粮船湾组火山岩石柱区的次生节理进行了研究,并探讨了柱状节理岩体的构造变形特征及过程。粮船湾组火山岩石柱区次生节理主要包括陡倾的纵节理及缓倾的横节理。前者多具有共轭剪节理的特征,形成于不同方向的挤压构造环境下;后者切割早期构造面理,形成于重力垮塌的构造环境,多发展为正滑断层。粮船湾组火山岩石柱总体上受次生节理改造明显,共轭节理反演的构造应力环境表明石柱区在140 Ma左右经历了快速的构造转换,主挤压应力由近NE-SW向转换为近NW-SE向,可能与莲花山断裂的构造活动相关。  相似文献   
994.
The main impact of the fishery for Tristan rock lobster Jasus tristani on seabirds at the Tristan archipelago and Gough Island is through night strikes, when petrels collide with a ship after being disorientated by its lights. Tristan fishery observers have kept records of night strikes on the MV Edinburgh since the 2010/2011 fishing season. Over the last three years, 723 seabirds from nine species were recorded coming aboard the fishing vessel, with at least 39 (5.4%) birds dying as a result. Birds killed were broad-billed prions Pachyptila vittata (41%), common diving petrels Pelecanoides urinatrix (23%), and storm petrels (Pelagodroma marina and Fregetta grallaria/tropica 36%). All these species are listed as Least Concern globally, and the numbers killed per year are <0.1% of the island populations. The captain and crew of the Edinburgh are aware of the problem posed by deck lights at night, and attempt to keep external lighting to a minimum. As a result, the numbers of birds coming aboard vessels in this fishery have decreased from an average of 130 birds per night in 1989 to less than two birds per night in 2010–2013. Currently, most incidents occur during exceptional events when circumstances require deck lights to be lit at night. Consideration should be given to banning fishing operations at night, at least on misty nights.  相似文献   
995.
Gaoping  Shen  Hiroshi  Ujilé Katsuo  Sashida 《Island Arc》1996,5(2):156-165
Abstract The pre-Neogene basement of the central Ryukyu Island Arc shows zonal structures analogous to those of the outer belt of southwest Japan. The innermost terrane (Iheya Zone) consists of isoclinally folded beds dipping northwestward; the anticlinal cores are composed mainly of Permian chert, whereas the synclinal parts are represented by Jurassic to Cretaceous sandstone-rich alternating siliceous shale and chert, bearing appropriate radiolarian fossils. At the east-central area of Ie Island, the basement rocks are exposed as a 172 m high peak, Tattyu. The flank area of Tattyu is composed of latest Jurassic to Berriasian siliceous shale and chert as part of an accretionary prism, while most of Tattyu is composed of a continuous and very compact sequence of Norian through Kimmeridgian (?) bedded chert which is rather gently inclined. Beyond an unexposed part below the Norian chert, Guadalupian chert is recognized. It is inferred that this pelagic chert (Tattyu sequence) was off-scraped and thrust on to the accretionary prism which developed on its flank area in an accretion process after the Early Cretaceous.  相似文献   
996.
内蒙古草原地层区的古生代地层   总被引:8,自引:0,他引:8  
对华北地台北侧大陆边缘,从寒武纪至石炭纪地层的沉积环境进行了系统地总结。其中以奥陶纪岛弧、晚志留世的磨拉石、泥盆纪和石炭纪的裂陷槽沉积具有区域意义。  相似文献   
997.
998.
Biostratigraphy of Famennian in Hainan Island, South China   总被引:1,自引:0,他引:1  
On the basis of the faunas including conodonts Palmatolepis gracilis sigmoidalis, P.gracilis gracilis, Polygnathus germanus, which are found for the first time, and corals Cystophrentis kalaohoensis it is confirmed that the Changjiang Formation refers to the Famennian, and may correlate with the Shaodong Formation and Menggongao Formation of central Hunan. This is the only Devonian deposits known in Hainan Island so far. It means that the outstanding problem of whether the Devonian rocks exist in that island is now settled. Meanwhile, the new evidences indicate that the lectostratotype section of Nanhao Formation of Baoting area refers to the Silurian,rather than the Lower Carboniferous as considered by most geologists formerly. Furthermore, the Member 3 of Nanhao Formation at Shilu-Jinbo district is proved to be the Upper Carboniferous,rather than Tournaisian or Middle-Upper Devonian as deemed to be before.  相似文献   
999.
主要讨论宇宙射线成因核素10Be(T 1/2= 1.5Ma)在大洋边缘海洋学尤其是中国近海海洋研究中的应用。在过去的近20年中,在中国开展的10Be研究在黄土堆积年龄及地层对比方面获得了诸多成果,但在海洋方面的应用研究距国际水平仍有一定的差距,尚需进一步加强。综述了海洋环境中10Be作为一个地球化学示踪剂的研究现状,着重介绍10Be在中国东部海域的收支平衡模式以及讨论10Be在太平洋西部边缘海及岛弧地区的应用前景。  相似文献   
1000.
The temporal and spatial distribution of total and organic particulate matter is investigated in the Bideford River estuary. Particulate matter is homogenously distributed in both the water column and the surface sediment, due to high rates of resuspension and lateral transport. The measured mean sedimentation rate for the estuary is 183·5 g of particulate matter m?2 day?1, of which more than half is due to resuspension.The surface sediment of the estuary is quantitatively the dominant reservoir of organic matter, with an average of 902·5 g of particulate organic carbon (POC) m?2 and 119·5 g of particulate organic nitrogen (PON) m?2. Per unit surface area, the sediment contains 450 times more POC and 400 times more PON than the water column. Terrestrial erosion contributes high levels of particulate matter, both organic and inorganic, to the estuary from the surrounding watershed. Low rates of sediment export from the estuary result in the accumulation of the terrigenous material. The allochthonous input of terrigenous organic matter masks any relationship between the indigenous plant biomass and the organic matter.In the water column, a direct correlation exists between the organic matter, i.e. POC and PON, concentration and the phytoplankton biomass as measured by the plant pigments. Resuspension is responsible for the residual organic matter in the water column unaccounted for by the phytoplankton biomass.The particulate content of the water column and the surface sediment of the estuary is compared to that of the adjacent bay. Water-borne particulate matter is exported from the estuary to the bay, so that no significant differences in concentration are noted. The estuarine sediment, however, is five to six times richer in organic and silt-clay content than the bay sediment. Since sediment flux out of the estuary is restricted, the allochthonous contribution of terrigenous particulate matter to the bay sediment is minor, and the organic content of the bay sediment is directly correlated to the autochthonous plant biomass.  相似文献   
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