1961—2017年华北地区高温日数及高温热浪时空变化特征   总被引：1，自引：1，他引：0  

邢佩  杨若子  杜吴鹏  党冰  轩春怡  熊飞麟 《地理科学》2020,40(8):1365-1376

利用华北地区85个气象站1961—2017年逐日最高气温资料,统计分析了华北地区高温日数及高温热浪（频次、持续时间、强度）的时空变化特征。结果表明：① 华北地区年高温日数整体呈增加趋势,自20世纪90年代中期之后年均高温日数明显增多;高温多出现在华北地区的南部和西部,华北地区大部分站点的高温日数呈增加趋势。② 就气候平均态而言,高温初日有略提前趋势,高温终日则明显推迟;空间上,绝大多数台站的高温终日呈推迟的趋势,其中京津冀中北部地区尤为明显。③ 累计高温热浪次数、轻度和中度热浪次数均整体增加,并在1990年左右明显由少变多,重度热浪次数增加趋势更为显著;1987年之后,平均每次高温热浪事件的高温有效积温明显增加,表明高温热浪的平均强度增大。④ 不同等级高温热浪总频次的空间分布特征相近,高频次区域均集中在内蒙古西部、山西西南部和河北南部;热浪累计频次的变化趋势在内蒙和山西以增多为主,在京津冀地区以减少为主。除山西南部和河北南部的个别站点以外,绝大多数站点的热浪平均持续天数和平均高温有效积温的变化呈增多增强趋势。总体来看,华北大部分区域自20世纪90年代以来,高温日数及热浪事件明显增强,同时存在明显的空间差异,研究结果将有助于进一步认识华北高温的区域性特征。  相似文献   

Establishing an early warning system for flash floods in Hoang Su Phi District,Ha Giang Province,Vietnam     

Thach Ngoc Nguyen  Canh Xuan Pham  Huy Quoc Nguyen  Toan Ngo Bao Dang 《Singapore journal of tropical geography》2019,40(2):312-333

Hoang Su Phi is a mountainous district in Ha Giang province, Vietnam. When the rainy season arrives in these parts, flash floods (besides landslides), frequently occur in many areas, seriously affecting the socio‐economic condition of the district. Therefore, in this paper, we have developed an early warning system for flash floods, established based on a geomorphological and hydrological approach. The basic principle underlying this system is the fact that flash floods will often occur where there is high potential risk with sufficient rainfall. In the model, eight parameters of the basin were used to build a potential flash flood map. Using the spatial processing module in an open source software, early predictions from automatic weather stations were interpolated and processed online to produce a potential risk map. Depending on the threshold of precipitation values, the results determined locations where flash flood may occur at various flash flood risk indices (FFRI). The system may be applied to support provision of early flash flood warning up to 1?6 days in advance in the district, allowing the local government ample time to make appropriate decisions on the prevention and/or mitigation of damages caused by flash flood hazards.  相似文献   

Molecular characterizations of chloramphenicol- and oxytetracycline-resistant bacteria and resistance genes in mariculture waters of China   总被引：1，自引：0，他引：1  

Hongyue Dang  Jingyi Zhao  Mingna Chen 《Marine pollution bulletin》2009,58(7):987-994

In order to gain an understanding of the diversity and distribution of antimicrobial-resistant bacteria and their resistance genes in maricultural environments, multidrug-resistant bacteria were screened for the rearing waters from a mariculture farm of China. Both abalone Haliotis discushannai and turbot Scophthalmus maximus rearing waters were populated with abundant chloramphenicol-resistant bacteria. These bacteria were also multidrug resistant, with Vibriosplendidus and Vibriotasmaniensis being the most predominant species. The chloramphenicol-resistance gene cat II, cat IV or floR could be detected in most of the multidrug-resistant isolates, and the oxytetracycline-resistance gene tet(B), tet(D), tet(E) or tet(M) could also be detected for most of the isolates. Coexistence of chloramphenicol- and oxytetracycline-resistance genes partially explains the molecular mechanism of multidrug resistance in the studied maricultural environments. Comparative studies with different antimicrobial agents as the starting isolation reagents may help detect a wider diversity of the antimicrobial-resistant bacteria and their resistance genes.  相似文献   

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曲国庆  党亚民  章传银  苏晓庆 《大地测量与地球动力学》2008,28(4):102-106

??С?????????е?????????????????????С???????????????????????????????????????????????????????????飬??????????????????????????????????????????ж??????????????,????????????????????????????  相似文献   

The Manila clam population in Arcachon Bay (SW France): Can it be kept sustainable?     

Cécile Dang  Xavier de Montaudouin  Mériame Gam  Christian Paroissin  Noëlle Bru  Nathalie Caill-Milly 《Journal of Sea Research》2010,63(2):108-118

The venerid clam Ruditapes philippinarum is the most prominent suspension-feeding bivalve inhabiting muddy intertidal seagrass beds in Arcachon Bay (SW France). It is exploited by fishermen, and Arcachon Bay ranks number one in France in terms of production and total biomass of this species. Previous studies revealed a decrease in the standing stock of R. philippinarum since 2003 and unbalanced length–frequency distributions with a lack of juveniles and of adults > 40 mm. Consequently, the population dynamics of this bivalve were studied at four intertidal sites and one oceanic site in Arcachon Bay. As clam size structure did not allow classical dynamics computations, field monitoring was coupled with field experiments (tagging–recapture) over two years. Monitoring of condition index and gonadal maturation stages highlighted a high variability in spawning number and intensity between sites. Recruitment events in the exploited area varied spatially but with uniformly low values. Von Bertalanffy Growth Function (VBGF) parameters (K, L_∞) were determined using Appeldoorn and ELEFAN methods. In the exploited sites in the inner lagoon, K was relatively high (mean = 0.72 yr^? 1) but L_∞ was low (mean = 41.1 mm) resulting in a moderate growth performance index (Φ′ = 2.99). Growth parameters were not correlated with immersion time and L_∞ was different between sites. Comparison of mortality coefficients (Z) between cage experiments and field monitoring suggested that fishing accounts for 65–75% of total adult mortality. Low recruitment, a low growth rate and a normal mortality rate led to low somatic production (4.1 and 8.7 g Shell-Free Dry Weight (SFDW) m^? 2 yr^? 1) and an annual P/B ratio from 0.44 to 0.92 yr^? 1. Under current conditions, the possibility of a sustainable population in Arcachon Bay will strongly depend on recruitment success and fishing management.  相似文献   

LLSVPs与全球热点空间叠置性再分析     

党牛  余星  胡航  许绪成  何虎  余娅娜 《地质学报》2022,96(12):4140-4148

地震层析成像显示在非洲和太平洋之下的核幔边界处(～2800 km)存在两个大型低剪切波速省(LLSVPs),分别被命名为Tuzo和Jason,指示温度或成分的异常。前人通过研究发现,大火成岩省喷发的古位置以及现今活动热点位置多位于LLSVPs边界±10°附近。由此,基于空间相关性,将LLSVPs狭窄的边界视为地幔热柱生成区,广泛用于解释地幔柱与热点的成因。但是,将一个深度2800 km的地球物理异常与地表热点建立联系,仍存在诸多不确定性。而且LLSVPs作为全球尺度的异常区,在地表的映射范围巨大,不可避免地与大量热点存在天然的空间叠置性,这种空间关联的程度以及是否具有成因联系仍然未知。本文考虑随机状态下热点落入LLSVPs范围的概率,对全球热点与LLSVPs边界重新进行空间分析,判断两者之间的空间叠置性。统计结果显示,全球热点与LLSVPs边界的空间相关性不及预期,Tuzo和Jason之间存在较大差异,Jason与热点缺乏空间位置相关性,而Tuzo与热点空间相关性较强。热点的分布与成因可能并不完全受控于LLSVPs。研究结果对普遍认为的LLSVPs与热点分布之间的强相关性提出质疑,在具...  相似文献   

中国金红石矿床地质及成因类型   总被引：5，自引：0，他引：5  

夏学惠  闫飞  赵玉海 《化工矿产地质》2007,29(3):185-192

根据矿床成因、成矿时代、成矿岩系及其变化特点、矿体及矿石特征等因素,将中国已知金红石矿床分为区域变质型(包括元古宙及古生代)、榴辉岩型、热液蚀变型、变质蚀变型及风化-沉积型5类。除形成于第四纪的风化-沉积型矿床之外,含矿层位多在泥盆系--新太古界之间,与变质作用及岩浆活动密切相关。不同类型矿床又各具特色。  相似文献   

Geological evolution,regional perspectives and hydrocarbon potential of the northwest Phu Khanh Basin,offshore Central Vietnam     

Michael B.W. Fyhn  Lars H. Nielsen  Lars O. Boldreel  Le D. Thang  Jørgen Bojesen-Koefoed  Henrik I. Petersen  Nguyen T. Huyen  Nguyen A. Duc  Nguyen T. Dau  Anders Mathiesen  Ian Reid  Dang T. Huong  Hoang A. Tuan  Le V. Hien  Hans P. Nytoft  Ioannis Abatzis 《Marine and Petroleum Geology》2009

Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area.  相似文献   

Factors controlling the distribution of transitional metal elements in marine hydrogenic ferromanganese crusts     

JIANG Xuejun）  ）*  YAO De）  LIN Xuehui）    ZHAI Shikui）） College of Geoscience  Ocean University of China  Qingdao  P. R. China ） Qingdao Institute of Marine Geology  China Geological Survey  P. R. China ） College of Georesources  Environmental Engineering  Sh  ong University of Technology  Zibo  P. R. China 《中国海洋大学学报(英文版)》2009,8(1):57-64

A series of selective dissolution experiments were conducted on the hydrogenic ferromanganese crusts collected near Line Island to study the geochemistry of Mn, Fe, Cu, Co, Ni and Ti. Despite of the fact that the very close intergrowth between amorphous ferric oxyhydroxides and δ-MnO2 exists in the hydrogenic ferromanganese crusts, there is no isomorphous substitution between iron and manganese. This is because the two elements in oxides have different crystal chemistry and geochemistry, such assertion bein...  相似文献