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1 Introduction The Qinghai-Tibet Plateau, known as the highest plateau with the most complex topography in the world, covers an area of more than 200km2, with a mean elevation of more than 4000m a.s.l. (Ye and Gao, 1979). Surrounded by the Earth’s highest mountains, such as the Himalayas, Pamir, Kunlun Mountains, the plateau plays a significant role in climate change in China even in the world, thus attracted great attention of researchers. Up to now, many achievements have been gained by…  相似文献   

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???ú??CORS?????????4???GPS????????????GAMIT/GLOBK??????е??????????????????????????????????????????????????????????????????????????3???????????????150 mm??11?′??????????4??????????????????10 mm/a????????溯?????????????????????????????????6′×6′?????????????????????????????????  相似文献   

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����Ms7.1����ǰ�����VTEC�쳣   总被引:1,自引:1,他引:0  
?????й???????????????GNSS???????????????????2010??4??14??????Ms7.1????????и???4??GNSS??????LHAS??LUZH??DLHA??WUSH??????TEC?????????????й???TEC??????????????????????TEC??????????????????LHAS??LUZH??WUSH???4??1????????????TEC?????????????LHAS??LUZH??DLHA???4??5???????????TEC?????????????TEC????????????????????5???????????????????????????й?????????  相似文献   

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徐闻珊瑚礁保护区营养盐时空分布特征   总被引:2,自引:1,他引:1  
2006年8月(夏季)、2006年11月(秋季)、2007年2月(冬季)和2007年4月(春季)在徐闻珊瑚礁自然保护区灯楼角至流沙湾近岸海域调查徐闻珊瑚礁保护区的营养盐变化及空间分布特征。结果表明:徐闻珊瑚礁保护区水域溶解态无机氮以NO3--N为主,其含量超过总溶解无机氮的50%;各站点NO2--N含量相对较低,冬季NO3--N和NH4+-N含量均高于其它季节;无机磷含量在0mg/L~0.030mg/L之间变化;活性硅含量表现为夏秋季节高、冬春季节低;表层水体硝酸盐氮/无机磷原子比值(N/P)夏季较低,不存在无机磷受限情况,而冬季N/P整体较高,此时水体主要受无机磷限制。  相似文献   

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The sea potato Acaudina spp. is a species of sea cucumber, belonging to the class Holothuroidea under Phylum Echinodermata. It becomes blooming recently in the East Sea of China, causing serious ecological problems. However, until now there are no molecular data for its larval identification and population genetic analysis. In this study, we firstly screened a mtDNA fragment and demonstrated that it was the species-specific molecular marker for the identification of Acaudina spp. We then developed a quantitative polymerase chain reaction(PCR) method to evaluate the larval density of Acaudina spp. based on this molecular probe. Utilizing this method, we examined 116 plankton samples collected in four seasons from 13 stations along the coastal region in Fujian province, China. The results showed that the high larval density was presented at stations 1, 2, and 3, which were near a quay in the coast. The larval density increased from April and reached the highest value in June and July, suggesting temperature might be the main environmental factor on the effects of its population distribution and density. Our work provides an important molecular tool for species identification and risk evaluation of a potentially invasive species.  相似文献   

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基于泊松分布的川东暴雨概率特征分析   总被引:1,自引:0,他引:1  
暴雨是川东地区主要的气象灾害之一,对经济建设有重大影响。为进一步揭示该地区暴雨的统计特征,利用川东地区有代表性的4个测站(重庆、达州、巴中、南充)47年间(1961-2007年)4-10月日降水量资料,借助于泊松分布模式对该地区暴雨概率特征进行了分析。结果表明:用泊松分布模式能很好地描述川东地区的暴雨概率分布特征;模式计算均得出所研究的4站每年出现3次暴雨的机率最大。  相似文献   

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利用积分法计算新疆地区9个无线电探空站2009~2013年的大气水汽转换系数K,将其作为真值,通过选取相同纬度、不同高程的探空站,分析Emardson模型对高程和时间的适用性;并均匀地选取5个探空站,逐年增加样本数据,解算不同样本的模型参数,建立对应的Emardson模型,预测其余4个探空站2014年的K值,验证Emardson模型在时间上的适用性。研究表明:1)在新疆地区,Emardson模型对高程和时间有较好的适用性;2)在时间分布上,增加样本数能在一定程度上提高Emardson模型的精度。  相似文献   

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We assessed the potential of marine ciliate community as an indicator to coastal water quality using water samples collected from four stations in the Yellow Sea in the summer 2000. The four stations were characterized by different levels of pollution. The ciliate communities consisted primarily of tintinnids and aloricate ciliates that were <30 μm. A total of 78 species were classified: 55 species at Station 2, 51 species each at Stations 1 and 4, and 47 species at Station 3. The mean number of species at each site was 29.2±2.0 (Station 1), 28.5±2.9 (Station 2), 27.8±1.7 (Station 3), and 24.5±2.3 (Station 4). The abundance was highly variable: 19 331±11 187 ind./L at Station 1, 7 960±5 639 ind./L at Station 2, 29 015±12 999 ind./L at Station 3, and 8 190±4 658 ind./L at Station 4. Our results suggest that neither the simple chemical analysis (e.g. chemical oxygen demand, dissolved inorganic nitrogen, and phosphate) nor the eutrophication/pollution index adequately described the water quality at the four stations. The same was true of the number of species and their abundance, both of which had no correlation with the chemical indices. In contrast, Margalef’s diversity index values (3.12 at Station 2, 2.89 at Station 1, and 2.64 at Stations 3 and 4) generally discriminated the water quality status of the four stations. The difference in water quality among the stations was strongly supported by the pattern of species richness (i.e. the total number of species) of ciliates at each station. Our evaluation was consistent with the results of long-term water quality monitoring at the four stations. With increasing eutrophication, we observed also a compositional and functional shift in the ciliate assemblages from algivorous oligotrich/choreotrich to nonselective-omnivorous gymnostomatids to bacterivorous-detrivorous scuticociliatids. Thus, ciliates may be used to indicate the coastal water quality status of a given site.  相似文献   

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计算内蒙古测震台网2019-12~2020-11山洞观测数据的加速度功率谱密度(PSD)和相应的概率密度函数(PDF),研究相应台站的背景噪声特征。结果表明,高频段背景噪声的昼夜差异显著,疫情防控期间噪声水平明显低于其他时段;次级微震频段背景噪声季节性变化显著,噪声水平冬季强、夏季弱,随着台站离海岸线距离增大,PSD峰值有逐渐减小的趋势;主微震频段背景噪声在10~20 s均有峰值,峰值冬季最强,春、夏、秋季基本没有差异,不同台站同一季节峰值差异小;长周期段噪声水平四季差异不大,春、夏季略高于秋、冬季。  相似文献   

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Two field studies were conducted to measure pigments in the Southern Yellow Sea (SYS) and the northern East China Sea (NECS) in April (spring) and September (autumn) to evaluate the distribution pattern of phytoplankton stock (Chl a concentration) and the impact of hydrological features such as water mass, mixing and tidal front on these patterns. The results indicated that the Chl a concentration was 2.43±2.64 (Mean ± SD) mg m?3 in April (range, 0.35 to 17.02 mg m?3) and 1.75±3.10 mg m?3 in September (from 0.07 to 36.54 mg m?3) in 2003. Additionally, four areas with higher Chl a concentrations were observed in the surface water in April, while two were observed in September, and these areas were located within or near the point at which different water masses converged (temperature front area). The distribution pattern of Chl a was generally consistent between onshore and offshore stations at different depths in April and September. Specifically, higher Chl a concentrations were observed along the coastal line in September, which consisted of a mixing area and a tidal front area, although the distributional pattern of Chl a concentrations varied along transects in April. The maximum Chl a concentration at each station was observed in the surface and subsurface layer (0–10 m) for onshore stations and the thermocline layer (10–30 m) for offshore stations in September, while the greatest concentrations were generally observed in surface and subsurface water (0–10 m) in April. The formation of the Chl a distributional pattern in the SYS and NECS and its relationship with possible influencing factors is also discussed. Although physical forces had a close relationship with Chl a distribution, more data are required to clearly and comprehensively elucidate the spatial pattern dynamics of Chl a in the SYS and NECS.  相似文献   

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With sulfide increasingly recognized as an important parameter to assess the oxidation-reduction level in aqueous environment, research on its geochemical behavior is becoming important. Water samples collected in Bohai Sea(1–19 August, 2010), Yellow Sea(20–30 November, 2010) and East China Sea(3–17 June, 2010 and 1–10 November, 2010) were used to determine the occurrence and distribution of dissolved sulfide by methylene blue spectrophotometric method. Results show that:(1) horizontally, concentration of dissolved sulfide significantly varied from the coastal region to the open sea and profoundly influenced by physical processes. High values occurred in the river-sea boundary zone "marginal filter" due to rich riverine input, frequent upwelling and active exchange in shelf edge. Terrestrial input from adjacent rivers and the current cycling contributed to the high sulfide appeared in western Bohai Sea, eastern Shandong Peninsula, and northeast of Changjiang(Yangtze) River estuary. Especially, relative higher sulfide values occurred in Yellow Sea, which is consistent with the variation of salinity largely due to the hydrodynamic feature;(2) vertically, measurement of dissolved sulfide in bottom water was higher and more variable than that in surface water caused by the wind-induced resuspension and dissimilatory sulfate reduction. Moreover, nutrient-type profile clearly identified that oxidation plays a major role in the biogeochemistry cycle of sulfide in water;(3) seasonally, investigation for East China Sea in June and November reflected seasonal variation of Changjiang River Diluted Water, Kuroshio Current, and Taiwan Warm Current. Concentration in June was much higher than that sampled in November at most stations. Mean concentration of dissolved sulfide varied seasonally from 2.26 μg/L(June) to 1.16 μg/L(November) in surface and 3.00 μg/L(June) to 1.56 μg/L(November) in bottom. Progress in the field is slow and more effort is needed to ensure the accuracy and reliability of determination and estimate the natural or anthropogenic contribution of dissolved sulfide in ecosystems.  相似文献   

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To understand the characteristics of macrobenthic structures and the relationship between environment and benthic assemblages in jellyfish bloom, we studied the macrobenthos and related environmental factors in the coastal waters of the Yellow Sea and East China Sea. Data were collected during two seasonal cruises in April and August of 2011, and analyzed with multivariate statistical methods. Up to 306 macrobenthic species were registered from the research areas, including 115 species of Polychaeta, 78 of Crustacea, 61 of Mollusca, 30 of Echinodermata, and 22 of other groups. Nine polychaete species occurred at frequencies higher than 25% from the sampling stations: Lumbrineris longifolia, Notomastus latericeus, Nin6e palmata, Ophelina acuminata, Nephtys oligobranchia, Onuphis geophiliformis, Glycera chirori, Terebellides stroemii, and Aricidea fragilis. Both the average biomass and abundance of macrobenthos are higher in August (23.8 g/m^2 and 237.7 ind./m^2) than those in April (11.3 g/m^2 and 128 ind./m^2); the dissimilarity ofmacrobenthic structures among stations is as high as 70%. In terms of the dissimilarity values, we divided the stations into four clusters in spring and eight in summer. The ABC curve shows that the macrofauna communities in high jellyfish abundance were not changed. Canonical correspondence analysis showed that depth, temperature, median grain size, total organic carbon of sediment and total nitrogen in sediment were important factors affecting the macrozoobenthic community in the study area.  相似文献   

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Bacterial diversity in sea ice brine samples which collected from four stations located at the Canada Basin, Arctic Ocean was analyzed by PCR-DGGE. Twenty-three 16S rDNA sequences of bacteria obtained from DGGE bands were cloned and sequenced. Phylogenetic analysis clustered these sequences within γ-proteobacteria, Cytophaga-Flexlbacter-Bacteroides (CFB) group, Firmicutes and Actinobacteria. The phylotype of Pseudoalteromonas in the γ-proteobacteria was predominant and members of the CFB group and γ-proteobacteria were highly abundant in studied sea ice brine samples.  相似文献   

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1INTRODUCTIONOneoftheeffectsofglobalwarmingisthatprecipita-tionhasincreasedoversomeareasintheworld,andthegaugedataofprecipitation (excludingAntarctica)showthatglobalprecipitationhasincreasedslightlybyabout9mmforthe20thcentury, whichwas verysmallcomparedwiththeinterannualandmul-ti-decadalvariability(NEWetal.,2001).Butregion-ally,thereexisted agreatdealofdifferences,suchasinmostpartsofAfrica, Amazon,westernSouthAmerica,theweatherhasbecomedrier,andinmostpartsofEuropeandCanada,thereexisted…  相似文献   

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INTRODUCTIONAlthoughdescriptionoflifehistoryandestimatesofanimalproductionhavealonghistory (Lin degaard ,1 989) ,fewstudiesontheproductionrateofbenthicmacroinvertebrateswerecarriedoutinChinesewaters (Liang ,1 984 ) .Withthedevelopmentoffisheriesandthedeterioratio…  相似文献   

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Studies on the diversity and distribution of bacterial populations will improve the overall understanding of the global patterns of marine bacteria and help to comprehend local biochemical processes and environments. We evaluated the composition and the dynamics of bacterial communities in the sediment of Jiaozhou Bay (China) using PCR-denaturing gradient gel electrophoresis (DGGE). Sediment samples were collected from 10 different sites in May, August, and November 2008 and in February 2009. There was significant temporal variation in bacterial community composition at all sites. However, the spatial variation was very small. The DGGE analyses of bacterial communities were used to divide the 10 stations into three types. Canonical correspondence analysis (CCA) revealed that the changes in bacterial communities were driven by sediment properties. Sequence analysis of DGGE band-derived 16S rRNA gene fragments revealed that the dominant bacterial groups in the sediment were of the classes γ-proteobacteria and δ-proteobacteria and phyla Bacteroidetes and Nitrospirae. Our results provide considerable insight into the bacterial community structure in Jiaozhou Bay, China.  相似文献   

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气温是最重要的气象因子之一,空间插值为台站气象数据降尺度提供了有效方法.本文利用江苏省67个气象台站2003年的逐日气温资料计算逐月平均气温和年平均气温,结合空间分辨率为30mX 30m的DEM数据,分别利用反距离权重法、张力样条插值法、普通克里格插值法和协同克里格插值法,对月和年平均气温进行插值,并利用交叉验证法对插...  相似文献   

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Zhang  Anqi  Liu  Honghan  Li  Chenhong  Chen  Changping  Liang  Junrong  Sun  Lin  Gao  Yahui 《中国海洋湖沼学报》2022,40(6):2401-2415

Toxic and harmful algal blooms are usually more frequent in mariculture areas due to the abundant trophic conditions. To investigate the relationship between toxic and harmful microalgae and environmental factors, we set up 12 stations near three mariculture regions (Gouqi Island, Sandu Bay, and Dongshan Bay) in the East China Sea. We collected samples from all four seasons starting from May 2020 to March 2021. We identified 199 species belonging to 70 genera, of which 38 species were toxic and harmful, including 24 species of Dinophyceae, 13 species of Bacillariophyceae, and 1 species of Raphidophyceae. The species composition of toxic and harmful microalgae showed a predominance of diatoms in the summer (August), and dinoflagellates in the spring (May), autumn (November), and winter (March). The cell densities of toxic and harmful microalgae were higher in summer (with an average value of 15.34×103 cells/L) than in other seasons, 3.53×103 cells/L in spring, 1.82×103 cells/L in winter, and 1.0×103 cells/L in autumn. Pseudonitzschia pungens, Prorocentrum minimum, Paralia sulcata, and Prorocentrum micans were the dominant species and were available at all 12 stations in the three mariculture areas. We selected 10 toxic and harmful microalgal species with frequency >6 at the survey stations for the redundancy analysis (RDA), and the results show that NO ?3 , water temperature (WT), pH, DO, and NO ?2 were the main factors on distribution of toxic and harmful microalgae. We concluded that the rich nutrient conditions in the East China Sea mariculture areas increased the potential for the risk of toxic and harmful microalgal bloom outbreaks.

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A serious sandstorm occurred in North China from April 5 to April 7, 2000, while the remote smallsand decending took place in even larger area to the far northeast China. In Chanchun city, smallsand descending with snow provides the best samples to conduct a quantitative research on the possible impacts of city- ecology. In the 253km2 urban district area of Changchun city, smallsands accumulated up to more than 3000t on April 7, according to the calculation of four "mud- snow" samples. After naturally melting in room temperature, two samples are taken to do quarantine of "invasion bacteria". As a preliminary result, the individual amount of bacterium in 1 ml sample water is up to 8.9 × 104 or 1.05 × 105, and it is estimated that there are 640 million "invasion bacterium" individuals in one square meter. This study proves that other than the obvious environmental effects of sandstorm, the urban micro- ecosystem is very possible under threat by the "invasion bacterium" accompanied by remote descending smallsand.  相似文献   

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