共查询到19条相似文献，搜索用时 328 毫秒
1.
南极磷虾是南大洋生态系统的关键物种, 种群聚集在南大洋的大西洋扇区。海冰在南极磷虾生活史中起着重要作用, 海冰及其冰下环境为磷虾越冬提供了避难场所, 但海冰是否为磷虾越冬提供了重要的饵料存在一定的争议, 对此问题的解决需要量化源于海冰的冰藻对南极磷虾越冬期间饵料及碳源的贡献。基于2020年冬季(3~8月)于南大洋大西洋扇区48.1亚区(布兰斯菲尔德海峡周边区域)和48.3亚区(南乔治亚岛周边海域)采集的磷虾样品, 通过两种高支链类异戊二烯化合物(IPSO25和HBI III)分别作为源于海冰的冰藻和源于水体浮游植物的生物标志物, 对两个区域冬季磷虾对冰藻和浮游植物的依赖进行研究。结果显示, 处于较高纬度、海冰密集度较高的48.1亚区的南极磷虾体内含有更高的IPSO25, 而处于开阔水域48.3亚区的磷虾体内有更高比例的HBI III, 另外48.3亚区磷虾的δ13C和δ15N稳定同位素显著高于48.1亚区的磷虾。48.1亚区南极磷虾越冬期间对浮游植物和冰藻的依赖与体长相关, 其中体长相对较短的早期成体呈现更高的依赖性, 同时该区域磷虾对冰藻的摄食提高了其营养级地位。48.3区南极磷虾越冬期间两种类异戊二烯含量与δ15N稳定同位素数值呈负相关关系, 表明该区域南极磷虾在初级生产匮乏时会摄食动物性饵料。若未来南大洋大西洋扇区海冰持续减少, 这将对整个磷虾种群、磷虾渔业的可持续发展和区域生态系统的稳定性产生威胁。 相似文献
2.
内壳是头足类重要的硬组织器官之一,鸢乌贼(Sthenoteuthis oualaniensis)内壳的生长具有不可逆性,是记录鸢乌贼整个生活史信息的良好载体。根据2019年3~5月中国灯光罩网渔船在西北印度洋生产调查期间采集的鸢乌贼样本,利用碳氮稳定同位素技术,研究了个体间的营养生态位关系、摄食习性等。结果表明,雌、雄鸢乌贼个体的内壳δ13C不存在显著性差异(P>0.05),而δ15N存在显著性差异(P<0.05)。营养生态位结果显示,雄性群体的生态位宽幅比雌性群体的要大。雌、雄个体的内壳生长对δ13C均没有显著影响(P>0.05),但雌、雄个体的内壳生长对δ15N均有显著影响(P<0.05), δ13C (1.28‰)和δ15N (3.46‰)值的变化表明鸢乌贼在生长过程中存在洄游现象,营养等级发生改变,且同时期的雌性个体较雄性个体捕食营养层级更高的食物。 相似文献
3.
大型海藻组织碳、氮含量及δ15N值的变化对于指示营养盐来源及营养盐评价研究具有重要的意义。为探究大型海藻组织碳、氮含量及δ15N值的变化特征，于2020年7月至2021年6月逐月分析了小长山岛潮间带孔石莼（Ulva pertusa）、角叉菜（Chondrus ocellatus）、鼠尾藻（Sargassum thunbergii）3种大型海藻组织的碳、氮含量和δ15N值的变化，并对其生长环境中海水的理化因子进行了测定。结果发现：孔石莼组织的氮含量与海水中的NO3-N和DIN含量之间存在显著的相关性，角叉菜组织的氮含量与海水中的NH3-N含量之间也存在显著的相关性。然而，大型海藻组织的碳含量和C/N比值与海水中的碳、氮营养盐之间并无显著的相关性。孔石莼组织的δ15N值与海水中的NO3-N和DIN含量之间也存在显著的相关性。因此，孔石莼适于用作NO3-N和DIN来源的指示藻种。结果指示小长山岛潮间带海水中具有供大型海藻生长利用的充足的营养盐，其主要受到生活污水和养殖排放的影响。 相似文献
4.
本文分析了2009、2010和2013年期间采集于哥斯达黎加、厄瓜多尔、秘鲁和智利外海的茎柔鱼的角质颚下颚的δ13C和δ15N含量。各海区的稳定同位素含量反应了不同海区背景值的不同，海区间稳定同位素含量差异显著，其中厄瓜多尔外海最低，智利外海最高。δ13C和δ15N散点图显示，尽管秘鲁海区的同位素值与哥斯达黎加和智利的存在一定的重叠，但是δ13C和δ15N值可明显将各海区的样本明显分开。哥斯达黎加、厄瓜多尔和智利外海样本的δ13C和δ15N值分布相对集中以及三海区之间的δ13C和δ15N值差异显著说明，采自哥斯达黎加、厄瓜多尔和智利外海的茎柔鱼样本属于不同地理群体，它们的产卵起源不同，各自在相对狭小的地理区域内移动，相互之间没有种群交流。与之相比，δ13C和δ15N值变化范围广说明，秘鲁外海茎柔鱼样本的幼体是来自不同海区，经理不同的移动路线和索饵场。秘鲁和智利外海茎柔鱼样本的同位素值存在一定的重叠可能是由于两者之间存在一定的种群交流所致。总体来说，通过分析茎柔鱼角质颚稳定同位素的空间差异有助于我们了解其不同地理种群的迁徙策略以及相互之间的连通性。 相似文献
5.
为节约成本和样品，一些学者同时分析海洋沉积物中的碳、氮及其同位素（TOC、TN、δ13C和δ15N）。分析沉积物中的δ13C，需要对样品进行酸化去除无机碳，但是这一酸化过程会使TN和δ15N的分析结果产生偏差，且偏差范围与沉积物中无机碳含量（CaCO3）有关。本研究选取了低CaCO3含量（1-16%）和高CaCO3含量（20-40%）的海洋沉积物样品，比较了酸化过程对TN和δ15N的影响。研究结果表明，酸化过程对海洋沉积物中TN和δ15N的分析结果产生了显著影响。对于低CaCO3含量的样品，酸化导致样品中TN流失了约0-40%，δ15N偏移了约0-2‰；而对于高CaCO3含量的样品，酸化导致样品中TN流失了约10-60%，δ15N偏移了约1-14‰。表明酸化对TN和δ15N的影响已经超过了仪器的误差范围0.002%（TN）和0.08‰（δ15N），将影响TN和δ15N的环境指示意义。因此，即使海洋沉积物样品中CaCO3含量很低，也必须用原样分析TN和δ15N以避免酸化过程的影响。 相似文献
6.
长棘海星[the Crown-of-Thorns Seastar （CoTS）；Acanthasterspp.]的暴发严重破坏珊瑚礁生态系统的功能和物种多样性, 其幼虫的存活率是决定成体种群密度的关键因素之一，因此了解长棘海星浮浪幼虫阶段的摄食及营养需求对于长棘海星灾害防控至关重要。本研究选用杜氏盐藻（Dunaliella salina）、牟氏角毛藻（Chaetoceros meülleri）、亚心形扁藻（Platymonas subcordiformis）和小球藻（Chlorella vulgaris）4种微藻喂养长棘海星幼虫，通过测定不同喂养条件下长棘海星幼虫的存活率、体长、体宽和胃面积等参数，结合4种微藻的营养含量，综合分析了不同微藻对长棘海星幼虫生长发育的影响。结果表明，不同的藻类投喂对长棘海星幼虫存活和生长发育产生显著的差异。幼虫生长到第16天时，牟氏角毛藻喂养的幼虫存活率为（7.20±0.01）％，所喂养幼虫的体长（678.83 μm）、体宽（391.04 μm）和胃面积（14 628.14 μm2）均显著高于杜氏盐藻、亚心形扁藻和小球藻喂养的幼虫。藻类生理指标和营养成分分析表明，牟氏角毛藻的蛋白质含量、能量、以及C20系列脂肪酸、饱和脂肪酸和单不饱和脂肪酸均高于杜氏盐藻和小球藻，而且其大小可能比较适宜幼虫的捕食。本研究表明特定种类的饵料藻类是决定幼虫发育的关键因素。 相似文献
7.
球形棕囊藻(Phaeocystis globosa)赤潮是一种全球范围的生态灾害,而硝酸盐稳定同位素技术是研究海洋富营养化与赤潮暴发机制的前沿技术。为将该技术应用于球形棕囊藻赤潮暴发机制方面的研究,首先需了解其同化吸收硝酸盐的稳定同位素分馏特征。为此开展了球形棕囊藻室内培养实验,获取培养过程中氮、磷、硅等营养盐的浓度及硝酸盐氮、氧稳定同位素(δ15N-NO3-、δ18O-NO3-)等参数的变化特征,计算球形棕囊藻同化吸收硝酸盐的稳定同位素分馏系数。结果显示,NO3-和PO43-浓度随培养时间均呈现先明显下降后稳定的特征,同时伴随直径2~3mm的囊体出现并生长至2~3cm。NH4+浓度先后两次出现升高,推测可能是受到有机氮矿化过程的补充所致。随NO3-浓度降低,δ15N和δ18O的值分别在第13天和第7天达到相对峰值。经计算,球形棕囊藻同化吸收硝酸盐过程δ15N和δ18O分馏系数分别为3.32‰±0.38‰和3.12‰±0.59‰,而前者的分馏系数呈逐渐降低的特点,原因可能是随球形棕囊藻生长,发生酶还原的NO3-较参与跨膜运输的NO3-比例逐渐升高。研究首次给出了球形棕囊藻同化吸收硝酸盐过程的氮、氧稳定同位素分馏系数及其变化特征,补充了海洋微藻同位素分馏数据库,为稳定同位素技术研究球形棕囊藻赤潮暴发的营养机制提供了重要的基础数据。 相似文献
8.
在1992～1993年度南极夏季期间，用肠道荧光法现场测定大磷虾（Euphausia superba Dana）的肠道排空率和肠道内含物色素水平，并据此计算自然状况下大磷虾的摄食率。大磷虾的肠道排空率为0.43／h。次成体（平均体重为168.8mg干重）和成体（平均体重为274.3mg干重）的摄食率分别为180.6±19.2和464.4±28.3ng叶绿素a／h。自然状况下大磷虾的摄食率与现场测定的100m以上水层平均叶绿素a浓度的相关性不大。 相似文献
9.
为了探究光背团水虱的食性特征，本研究利用碳、氮稳定同位素技术于2015年冬季和2016年夏季对广西北海廉州湾红树林中光背团水虱及其食物来源的碳、氮稳定同位素比值（δ13C值和δ15N值）进行分析。结果显示，冬季和夏季光背团水虱的δ13C值大小范围为-22.85‰~-21.87‰，平均值为（-22.46±0.35）‰；δ15N值大小范围为11.02‰~12.85‰，平均值为（11.88±0.56）‰；光背团水虱的δ13C值、δ15N值变化范围较小，表明其食物来源较为简单。单因素方差分析结果显示，冬季与夏季光背团水虱的平均δ13C值差异不显著（P>0.05），而夏季的δ15N值普遍高于冬季δ15N值，差异显著（P<0.05）；不同生长阶段的光背团水虱δ13C值、δ15N值会随着体长的增长而增大，差异显著（P<0.05），表明光背团水虱在生长的过程中可能发生了食性转变。光背团水虱的δ13C值与浮游生物的δ13C值相近，而与红树植物δ13C值差距较远，说明光背团水虱主要以浮游生物为食物来源。基于R语言稳定同位素混合模型（SIAR）计算结果显示，冬季和夏季各粒径级别浮游生物对不同生长阶段的光背团水虱的贡献率趋势基本一致，表现为1.2~25 μm粒级的浮游生物对光背团水虱平均贡献率最高，其次为25~50 μm粒级，粒径大于100 μm的浮游生物对体长小于5.5 mm的光背团水虱贡献率较低，对体长大于5.5 mm的光背团水虱的贡献率随着体长增大而相应增大，说明不同生长阶段的光背团水虱食性有差异。对光背团水虱食性分析的结果可为深入研究团水虱爆发的原因及危害红树林的作用机理提供基础资料。 相似文献
10.
海藻场是生物多样性最高的生态系统之一, 其内部的沉积物有机质是支撑海藻场生物多样性的重要物质基础之一。本研究以浙江省嵊山岛北部无人村沿岸的天然海藻场为研究对象, 在大型海藻凋落期6~8月采集沉积物和端元生物样本, 分析了沉积物样本的粒径组成、总有机碳 (TOC)、总氮(TN)、碳氮比值(C/N)和碳氮稳定同位素(δ13C和δ15N), 通过贝叶斯稳定同位素混合模型评估了沉积物有机质的来源及变化规律。结果显示, 1)海藻场沿岸沉积物中粉砂占比最大, 砂的占比最低, 沉积物类型为黏土质粉砂; 2)沉积物TOC、TN、C/N、δ13C和δ15N范围分别为0.70%~2.41%、0.11%~0.41%、5.53~6.48、–21.79‰~–19.60‰和1.56‰~4.26‰, 在空间分布上, TOC与TN含量均随离岸距离增加而下降; 3)沉积物粒径组成、C/N比值、δ13C和δ15N之间的关系显示沉积物有机质主要来源于大型海藻和浮游植物的混合贡献; 4)根据贝叶斯同位素混合模型计算结果显示, 大型海藻对沉积物有机质贡献率在2.30%~45.60%, 在空间分布上, 大型海藻对沉积物有机质的贡献率随离岸距离增加而下降; 5)海藻碎屑产生量和沉积物有机碳沉积量评估结果显示, 大型海藻产生的碎屑有机质中有11.98%进入海藻场及沿岸海域的表层沉积物中。本研究为评估海藻场碎屑的产生规模和时空分布, 以及渔业资源养护功能提供了数据支撑。 相似文献
11.
As one of the most common and dominant species in the Southern Ocean, Antarctic krill(Euphausia superba)play a significant role in food web structure and the process of energy flow. The diet of Antarctic krill in the Prydz Bay during austral summer of 2012/2013 was investigated and the ontogenetic shift in krill diet was evaluated using the stable isotope method. The nitrogen stable isotope values(δ~(15) N) of adults((2.78±0.58)‰) were much higher than those of juveniles((1.69±0.70)‰), whereas the carbon stable isotope values(δ~(13) C) of adults(–(28.26±1.08)‰) were slightly lower than those of juveniles(–(27.48±1.35)‰). Particulate organic matter(POM)from 0, 25, and 50 m depth combined(0/25/50 m) represented phytoplankton food items. The results showed that phytoplankton food items in surface water and mesozooplankton were two essential food items for Antarctic krill in the Prydz Bay during summer. POM(0/25/50 m) contributes 56%–69% and 26%–34% to the diet of juvenile and adult krill, respectively, whereas mesozooplankton composes 13%–34% and 58%–71% of the diet of juvenile and adult krill, respectively. Thus, an ontogenetic diet shift from POM(0/25/50 m), which consists mainly of phytoplankton, to a higher trophic level diet containing mesozooplankton, was detected. The capacity for adults to consume more zooplankton food items may minimize their food competition with juveniles, which rely mostly on phytoplankton food items. This suggests "diet shift with ontogeny" which may somehow help krill keep their dietary energy budget balanced and well adapted to the Antarctic marine ecosystem as a dominant species. 相似文献
12.
Intensive observations using hydrographical cruises and moored sediment trap deployments during 2010 and 2012 at station K2 in the North Pacific Western Subarctic Gyre (WSG) revealed seasonal changes in δ 15N of both suspended and settling particles. Suspended particles (SUS) were collected from depths between the surface and 200 m; settling particles by drifting sediment traps (DST; 100–200 m) and moored sediment traps (MST; 200 and 500 m). All particles showed higher δ 15N values in winter and lower in summer, contrary to the expected by isotopic fractionation during phytoplankton nitrate consumption. We suggest that these observed isotopic patterns are due to ammonium consumption via light-controlled nitrification, which could induce variations in δ 15N(SUS) of 0.4–3.1 ‰ in the euphotic zone (EZ). The δ 15N(SUS) signature was reflected by δ 15N(DST) despite modifications during biogenic transformation from suspended particles in the EZ. δ 15N enrichment (average: 3.6 ‰) and the increase in C:N ratio (by 1.6) in settling particles suggests year-round contributions of metabolites from herbivorous zooplankton as well as TEPs produced by diatoms. Accordingly, seasonal δ 15N(DST) variations of 2.4–7.0 ‰ showed a significant correlation with primary productivity (PP) at K2. By applying the observed δ 15N(DST) vs. PP regression to δ 15N(MST) of 1.9–8.0 ‰, we constructed the first annual time-series of PP changes in the WSG. This new approach to estimate productivity can be a powerful tool for further understanding of the biological pump in the WSG, even though its validity needs to be examined carefully. 相似文献
13.
In this study, the dB difference and characteristics of krill swarms inhabiting Subarea 48.1, which includes the west and south of the South Shetland Island and the Elephant Island peripheries, were estimated to distinguish Antarctic krill, using acoustics. From April 13 to 24, 2016, acoustic data were collected along 24 survey lines using the frequencies 38 and 120 kHz, and middle trawling was performed at 7 stations. Using the difference between the dB values of two volume backscattering strength (Sv) frequencies (38 and 120 kHz), a clear acoustic distinction could be made between Antarctic krill (4.9 to 12.0 dB) and fish (?4.0 to ?0.2 dB). The distributions and mean Sv of krill swarms in the Elephant Island peripheries and south of South Shetland Island were higher than those in the west of South Shetland Island. The mean length/ height ratio of krill swarms in the west of the South Shetland Island (64.5) was higher than that in the south (35.9) and the Elephant Island peripheries (33.8), with the length of the aggregations exceeding their height. Most krill swarms were distributed between the surface layer (less than 10 m below sea level) and within 200 m of water depth. These results are expected to serve as baseline data for evaluating krill density and biomass by distinguishing them from fish, using acoustics. 相似文献
14.
The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber(A. japonicus) and prawn(Penaeus japonica) polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from(–25.47±0.20)‰ to(–16.48±0.17)‰(mean±SD), and δ15N ranged from(4.23±0.49)‰ to(12.44±0.09)‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was(2.75±0.08). P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level(2–3); jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level(1–2); and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level(0–1). 相似文献
15.
《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(2):377-394
Temporal changes in δ15N values of sinking particles collected with sediment traps in the Benguela upwelling regime off southwest Africa mirrored variations in the input of inorganic nitrogen to the surface water. Reductions in δ15N (to as low as 2.5‰) corresponded to low sea surface temperatures during austral spring and late austral autumn/early winter, indicating increased nitrate availability due to the presence of recently upwelled water. High particulate fluxes accompanied the low δ15N values and sea surface temperatures, reflecting increased productivity, fueled by the upwelled nutrients. High δ15N values (up to 13.1‰) coincided with high sea surface temperatures and low particle fluxes. In this area, the seaward extension of upwelling filaments, which usually occurs twice yearly, brings nutrient-rich water to the euphotic zone and leads to elevated productivity and relatively lower δ15N values of the particulate nitrogen. Satellite images of ocean chlorophyll show that productivity variations coincide with δ15N changes. The observed isotopic pattern does not appear to have been caused by variations in the species composition of the phytoplankton assemblage. Calculations based on δ15N of the sinking particulate nitrogen show that the surface nitrate pool was more depleted during late austral summer/early fall and mid-winter and that supply exceeded demand during the intense spring bloom and in late austral fall. The main uncertainty associated with these estimates is the effect of diagenesis on δ15N and possible variability in preservation of the isotope signal between periods of high and low particle flux. 相似文献
16.
海草凋落叶的溶解有机物的释放及其生物地球化学意义 总被引：1，自引：0，他引：1
Dissolved organic matter(DOM) represents a significant source of nutrients that supports the microbial-based food web in seagrass ecosystems. However, there is little information on how the various fractions of DOM from seagrass leaves contributed to the coastal biogeochemical cycles. To address this gap, we carried out a 30-day laboratory chamber experiment on tropical seagrasses Thalassia hemprichii and Enhalus acoroides. After 30 days of incubation, on average 22% carbon(C), 70% nitrogen(N) and 38% phosphorus(P) of these two species of seagrass leaf litter was released. The average leached dissolved organic carbon(DOC), dissolved organic nitrogen(DON) and dissolved organic phosphorus(DOP) of these two species of seagrass leaf litter accounted for 55%, 95% and 65% of the total C, N and P lost, respectively. In the absence of microbes, about 75% of the total amount of DOC, monosaccharides(MCHO), DON and DOP were quickly released via leaching from both seagrass species in the first 9 days. Subsequently, little DOM was released during the remainder of the experiment. The leaching rates of DOC, DON and DOP were approximately 110, 40 and 0.70 μmol/(g·d). Leaching rates of DOM were attributed to the nonstructural carbohydrates and other labile organic matter within the seagrass leaf. Thalassia hemprichii leached more DOC, DOP and MCHO than E. acoroides. In contrast, E. acoroides leached higher concentrations of DON than T. hemprichii, with the overall leachate also having a higher DON: DOP ratio. These results indicate that there is an overall higher amount of DOM leachate from T. hemprichii than that of E. acoroides that is available to the seagrass ecosystem. According to the logarithmic model for DOM release and the in situ leaf litter production(the Xincun Bay, South China Sea), the seagrass leaf litter of these two seagrass species could release approximately 4×10~3 mol/d DOC, 1.4×10~3 mol/d DON and 25 mol/d DOP into the seawater. In addition to providing readily available nutrients for the microbial food web, the remaining particulate organic matter(POM)from the litter would also enter microbial remineralization processes. What is not remineralized from either DOM or POM fractions has potential to contribute to the permanent carbon stocks. 相似文献
17.
太平洋褶柔鱼为大洋性经济鱼种，具有一年生命周期，其资源变动受气候和海洋环境条件的显著影响。本研究根据日本提供的2003-2012年太平洋褶柔鱼冬生群体的渔业统计数据，结合产卵场环境数据以及尼诺指数ONI（定义为Niño 3.4区海表温度距平值），分析不同气候条件下（厄尔尼诺和拉尼娜）太平洋褶柔鱼冬生群体产卵场海表温度（SST）、叶绿素a（Chl-a）浓度以及适宜产卵面积（SSA）的变动情况及对其资源丰度（CPUE）的影响。结果表明，太平洋褶柔鱼冬生群体产卵场SST、Chl-a浓度和SSA具有明显的季节性变化。相关分析表明，各年CPUE与Chl-a浓度以及SSA具有显著的正相关关系（p<0.05），但与SST相关性不显著（p>0.05）。此外，厄尔尼诺和拉尼娜事件通过驱动太平洋褶柔鱼冬生群体产卵场SSA和关键海域（25°-29°N，122.5°-130.5°E）内的Chl-a空间分布和大小变化，从而改变其资源丰度，但影响作用随各异常事件的强度不同而变化，具体表现为：发生弱强度厄尔尼诺事件时，产卵场SSA较高，Chl-a浓度处于较低水平，导致资源补充量处于较低水平，CPUE降低；发生中等强度厄尔尼诺事件时，产卵场SSA较低，但Chl-a浓度处于较高水平，导致资源补充量增加，CPUE处于上升水平；发生中等强度拉尼娜事件时，产卵场SSA和Chl-a浓度均处于较高水平，资源补充量显著增加，CPUE显著升高。研究表明，厄尔尼诺和拉尼娜事件对太平洋褶柔鱼冬生群体产卵场摄食孵化环境和资源丰度变动具有显著影响。 相似文献
18.
Results obtained from simulating the propagation of infrasonic waves from the Chelyabinsk meteoroid explosion observed on February 15, 2013, are given. The pseudodifferential parabolic equation (PDPE) method has been used for calculations. Data on infrasonic waves recorded at the IS31 station (Aktyubinsk, Kazakhstan), located 542.7 km from the likely location of the explosion, have been analyzed. Six infrasonic arrivals (isolated clearly defined pulse signals) were recorded. It is shown that the first “fast” arrival (F) corresponds to the propagation of infrasound in a surface acoustic waveguide. The rest of the arrivals (T1–T5) are thermospheric. The agreement between the results of calculations based on the PDPE method and experimental data is satisfactory. The energy E of the explosion has been estimated using two methods. One of these methods is based on the law of conservation of the acoustic pulse I, which is a product of the wave profile area S/2 of the signal under analysis and the distance to its source E I [kt] = 1.38 × 10–10 (I [kg/s])1.482. The other method is based on the relation between the energy of explosion and the dominant period T of recorded signal E T [kt] = 1.02 × (T [s]2/σ)3/2, where σ is the dimensionless distance determining the degree of nonlinear effects during the propagation of sound along ray trajectories. According to the data, the explosion energy E I,T ranges from 1.87 to 32 kt TNT. 相似文献
19.
PARK Mirye PARK So Yun HWANG Jinik JUNG Seung Won LEE Juyun CHANG Man LEE Taek-Kyun 《海洋学报(英文版)》2018,37(5):107-112
Microalgae are photosynthetic microorganisms that function as primary producers in aquatic ecosystems. Some species of microalgae undergo rapid growth and cause harmful blooms in marine ecosystems. Heterocapsa triquetra is one of the most common bloom-forming species in estuarine and coastal waters worldwide. Although this species does not produce toxins, unlike some other Heterocapsa species, the high density of its blooms can cause significant ecological damage. We developed a H. triquetra species-specific nuclease protection assay sandwich hybridization (NPA-SH) probe that targets the large subunit of ribosomal RNA (LSU rRNA). We tested probe specificity and sensitivity with five other dinoflagellates that also cause red tides. Our assay detected H. triquetra at a concentration of 1.5×104 cells/mL, more sensitive than required for a red-tide guidance warning by the Korea Ministry of Oceans and Fisheries in 2015 (3.0×104 cells/mL). We also used the NPA-SH assay to monitor H. triquetra in the Tongyeong region of the southern sea area of Korea during 2014. This method could detect H. triquetra cells within 3 h. Our assay is useful for monitoring H. triquetra under field conditions. 相似文献