Spectral observations of blue stellar objects from FBS in the zone δ =+39°     

P. K. Sinamyan  A. M. Mickaelian 《Astrophysics》2008,51(1):37-47

Spectral observations of blue stellar objects from FBS are reported for the purpose of classifying them, discovering interesting new objects, and studying the FBS sample as a whole. 59 FBS objects in the zone with central declination δ =+39° were observed with the 2.6-m telescope at the Byurakan Observatory during 1987–1991. The images have been digitized with a professional scanner and processed by MIDAS in a way similar to CCD spectra. In addition, 4 objects were observed with the BAO-2.6 and OHP-1.93 telescopes using modern techniques during 1997–2000. 3 white dwarfs, 45 hot subdwarfs, 4 HBB stars, and 2 class F stars were discovered. Spectra of 20 of the most interesting objects are shown. __________ Translated from Astrofizika, Vol. 51, No. 1, pp. 51–59 (February 2008).  相似文献   

广西涠洲岛滨海湿地潮下带海草、红树林与互花米草的分布和群落结构特征          下载免费PDF全文

邱广龙  潘良浩  王欣  苏治南  方超  范航清 《应用海洋学学报》2021,40(1):56-64

系统报道了广西涠洲岛的潮下带海草、红树林以及互花米草的分布和群落结构特征。2019—2020年的调查结果表明,涠洲岛海草分布于南湾西侧,紧邻珊瑚礁区,面积4246 m 2,为潮下带的生长形式,海草种类仅见卵叶喜盐草(Halophila ovalis);真红树植物有6种[红海榄(Rhizophora stylosa)、海漆(Excoecaria agallocha)、白骨壤(Avicennia marina)、桐花树(Aegiceras corniculatum)、卤蕨(Acrostichum aureurm)以及外来种无瓣海桑(Sonneratia apetela)],占广西真红树种类的50%,分布于涠洲岛西北部的西角沟、北部的牛角坑沟和东南部的五彩滩,总面积约450 m^2;半红树植物6种,占广西半红树种类的75%;外来种互花米草(Spartina alterniflora)仅见于西北部的西角沟,面积处于快速扩展阶段(现存面积70 m^2,比9个月前的面积增加了2倍)。尽管涠洲岛的红树林和海草床面积均较小,但却是我国为数不多三大典型海洋生态系统(红树林、海草床和珊瑚礁)共存的区域,具有较高的保护价值和科学价值。涠洲岛滨海湿地的管理,应加大对乡土红树植物的保护力度,并密切跟踪监控外来种无瓣海桑和互花米草,必要时进行人工清除。此外,应积极防范有害藻华的发生,以免对涠洲岛海草床乃至整个海洋生态系统产生负面影响。  相似文献   

南海西沙永乐龙洞沉积物组成、来源及其沉积作用     

范德江  田元  傅亮  罗珂  孙晓霞  毕乃双  姚鹏  刘光兴  陈洪举  杨作升 《海洋与湖沼》2018,49(6):1203-1210

南海永乐龙洞发育于永乐珊瑚礁台地,龙洞深度达300m,为世界之最。沉积物堆积在龙洞的洞壁斜坡、龙洞中部的转折平台以及洞底等部位。使用激光粒度仪、X射线粉晶衍射仪、X射线荧光光谱仪等对采自不同深度的沉积物进行了粒级、矿物物相、元素含量的研究。研究结果表明:龙洞沉积物绝大部分为钙质生物碎屑,以砂粒级碎屑为主,含砾石碎屑、粉砂碎屑,分选和磨圆差;沉积物矿物组成以文石、高镁方解石为主,含少量低镁方解石,其平均含量分别为69%、28%、3%;化学组成以Ca、Mg、Sr为主,平均含量分别为35.5%、0.9%、0.5%,含少量Si、Al、Ti、P、S等元素。该区沉积物来源包括礁坪生物碎屑和东亚季风风尘陆源物质两个方面,以礁坪来源的生物碎屑为主;龙洞沉积作用包括机械捕获作用和垂直沉降作用两种方式,而以机械捕获作用为主。  相似文献   

国际蓝碳合作发展与中国的选择   总被引：2，自引：0，他引：2  

赵鹏  胡学东 《海洋通报》2019,38(6):613-619

海洋储存了地球上93%的CO_2,是全球最大的碳库。发挥海洋固碳、储碳作用,对应对全球气候变化具有重要意义。《联合国气候变化框架公约》和《巴黎协定》是2020年后国际气候治理的基础,为国际蓝碳合作指明了方向,也提供了国际法依据。当前,国际蓝碳合作从科学研究向纳入国际气候治理方向不断推进,不少国际组织和国家已着手推动蓝碳国际规则制定。中国蓝碳资源分布广泛,特色鲜明,蓝碳发展起步阶段里中国的参与不仅是对全球应对气候变化的重要贡献,更有助于通过蓝碳合作增强我国在全球气候治理和海洋治理领域的影响力和话语权。我国蓝碳发展应从国内、国际两个方面着手。在国内夯实基础、补足短板,加强蓝碳基础研究和实践,建立蓝碳评估标准,加快蓝碳人才队伍建设。在国际上积极参与现有国际蓝碳计划,在"21世纪海上丝绸之路"等机制框架下开展双、多边蓝碳合作,推动全球蓝碳治理,从积极参与向适时引领发展。  相似文献   

MODIS和OMI数据评估阅兵期间北京市大气减排成效     

张晗  余超  苏林  李令军  范萌  王雅鹏  陈良富 《遥感学报》2017,21(4):622-632

卫星观测不仅能反映区域宏观大气污染状况,也能从城市尺度上监测大气污染物的变化。基于以上优势,本文利用MODIS气溶胶光学厚度(AOD)和OMI对流层NO_2垂直柱浓度数据,比较2015年与2012年—2014年以及2015年3个时期(减排前、减排中、减排后)AOD和NO_2柱浓度的变化,定性分析了阅兵期间华北平原地区污染物减排效果,重点定量评估北京市联控减排措施的效果。研究发现2015年减排中华北平原重污染地区AOD和NO_2柱浓度相比于前3年同期有明显降低。定量分析北京市的减排效果得到:2015年减排中较前3年同期而言,AOD降低59%,NO_2柱浓度降低41%;较2015年减排前而言,AOD降低73%,NO_2柱浓度降低30%,去除气象条件影响后,AOD下降43%,NO_2柱浓度下降21%,说明严格的联控减排措施有效地改善了空气质量,气象条件也起到积极的作用。减排措施结束后,AOD和NO_2柱浓度比减排中分别增加159%和71%。研究结果表明,卫星遥感与地基监测评估效果相当,能反映北京地面污染物排放能力;它既能观测区域尺度大气污染变化,又可评估城市尺度大气污染减排。随着卫星技术水平的提高,期望未来卫星遥感可作为一种独立手段来定量评估区域及城市尺度空气质量减排措施的效果。  相似文献   

山东省日照市蓝色经济区城市三维地质结构调查及三维建模          下载免费PDF全文

秦泗伟  吉烜莹  姜洪胜  廉永彪 《山东国土资源》2022,38(4)

针对日照市城市可持续发展中面临的地质环境和地质资源问题,开展蓝色经济区城市三维地质结构调查。运用先进的勘察技术、地理信息系统技术、三维地质建模技术,开展城市三维地质结构填图,建立了日照市钻孔三维实体、第四系结构、基岩结构三维模型。通过数字曲面拟合和计算机图形学的方法,把空间分布不均匀、不连续、散乱的地质信息变成可视的、连续的、形象直观的三维地质模型,以三维图象的形式形象地表达了各种地质结构的真实形态、特征,圈定影响深基础开挖和地下空间利用的不良地质体范围,为日照市地下空间资源开发利用提供地质依据。  相似文献   

First documented southern transatlantic migration of a blue shark Prionace glauca tagged off South Africa     

《African Journal of Marine Science》2013,35(3):639-642

The first documented recapture of a South African-tagged juvenile blue shark Prionace glauca off Uruguay lends weight to the hypothesis of a single blue shark population in the South Atlantic. The presence of neonate blue sharks with umbilical scars and females with post-parturition scars, as well as the high frequency of small juveniles in research longline catches, confirm the existence of a parturition and nursery area off South Africa. The final positions of three tagged sharks suggest that large-scale movement patterns in the South Atlantic are a mirror image of movements in the North Atlantic, with sharks using the north-westerly Benguela Drift to migrate into the tropics and ultimately across into South American waters. The confirmed existence of a parturition and nursery area off the south coast of South Africa and the movement of sharks into both adjacent ocean basins suggest that the southern African blue sharks are part of a single stock that straddles the South Atlantic and Indian oceans, and possibly the entire Southern Hemisphere.  相似文献   

Insights into zooplankton‐cyanobacteria interactions derived from enclosure studies     

Carolyn W. Burns 《新西兰海洋与淡水研究杂志》2013,47(3):477-482

Few workers have used enclosures specifically to study interactions between zoo‐plankton and cyanobacteria. Differences among studies in enclosure size, nutrient level, plankton abundance and species composition, presence or absence of fish, and length of experiments make generalisations difficult. Zooplankton had no direct effect on the growth of ungrazed cyanobacteria (Anabaena flos‐aquae, Aphanizomenon flos‐aquae, large Microcystis colonies) in short‐term (<5 days) and long‐term (> 1 month) enclosure studies. When large cyanobacteria were abundant, some Daphnia spp. snowed reduced reproduction and development. When large grazers were abundant they suppressed the growth of edible, colonial cyanobacteria (Aphanizomenon elenkinii, small Microcystis colonies). By altering the ambient light and nutrient environment, large zooplankton may suppress cyanobacteria; evidence for the importance of grazers in promoting cyanobacterial dominance by removing competing phytoplankton species is equivocal. Zooplankton may suppress nitrogen fixation by cyanobacteria through ammonia excretion and may promote a change in dominance from diatoms to cyanobacteria through recycling phosphorus but not silicon.  相似文献   

Light‐dependence of photosynthesis and growth in cyanobacteria: Implications for their dominance in eutrophic lakes     

Max M. Tilzer 《新西兰海洋与淡水研究杂志》2013,47(3):401-412

In eutrophic lakes cyanobacteria are favoured relative to other phytoplankton, both under stratified and mixed conditions. During stratification, gas vacuole formation allows the accumulation of dense surface scums which attain the highest possible area‐specific photosynthetic rates in aquatic environments owing to high irradiances, near‐complete harvesting of impinging light, and minimal light inhibition and photo‐oxidation. During moderate mixing, high yields of biomass can be achieved by effective light harvesting for photosynthesis (aided by phycobilin pigments) and low maintenance energy requirements at low mean irradiances. Howevrr, nitrogen fixation competes for energy and reductant with photosynthesis, and leads to a decline of light‐saturated maximum growth rates. Wind‐driven vertical mixing and lateral advection are the main causes for the instability of cyanobacterial blooms in hyper‐eutrophic lake ecosystems.  相似文献   

磷锑钼蓝光度法测定红土镍矿中磷量          下载免费PDF全文

司银奎 《山东国土资源》2012,28(12):52-54

试样经烘干处理后,利用硫酸和氢氟酸溶矿,硝酸提取,加氨水以氢氧化铁为载体沉淀磷酸盐,分离镍、铬、钴、铜等干扰离子,制备成硝酸溶液。中和后,以钼酸铵—酒石酸锑钾为显色剂,以抗坏血酸为还原剂,显色,在700nm处测量吸光度,利用计算机拟合标准曲线计算磷含量。此方法精密度与加标回收率均能满足质量要求。  相似文献