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321.
闽江口第四纪地层中的孢粉、有孔虫、硅藻组合及其古地理意义 总被引:7,自引:1,他引:7
本文通过对闽江口琅岐岛钻孔的孢粉,有孔虫及硅藻的综合分析,发现第四纪地层中有五个孢粉组合带,五个硅藻组合带与一个微体化石层。结合~(14)C测年资料与沉积物特征认为该地区第四纪地层可以划分为晚更新世晚期与全新世(早期、中期、晚期)。气候演化依次为:冷干→温暖略干→温暖湿润→炎热潮湿→温暖略干。沉积相发展顺序为:冲积相、冲洪积相→河流相、湖沼相→湖沼相、河口相→海湾相→河口相。 相似文献
322.
黄、东海毗邻海域悬浮体与水团的对应关系及影响因素 总被引:2,自引:0,他引:2
对黄、东海毗邻海域由陆架到深海的悬浮体进行了大量加密取样,获得了较准确的结果。给出了悬浮体含量及其三维分布,确定它们与水团及其边界有良好的对应关系。并从物源、动力和成因等解释了这种对应,提出了水团对悬浮体研究的重要意义。研究表明黑潮次—中层混合爬升水及其混合水形成悬浮体含量最低值区,横亘在陆架与深海之间,形成阻隔含有大部分悬浮体的陆架中、下层水体向深海输送的洁净“水障”,台湾暖流北上的顶托也起类似作用,并分析了影响悬浮体含量的各种因素及有关机制。 相似文献
323.
324.
325.
养殖对虾与海捕对虾鉴别方法初探 总被引:1,自引:1,他引:1
通过对养殖中国对虾(Penaeus orientalis)和海捕中国对虾肌肉煮熟后的失水率,提取物中的甜菜碱和氧化三甲胺含量,以及虾肉脂质中所含脂肪酸组成和含量进行了分析比较,得到下列结果:(1)两类对虾鲜样煮熟后失水率相差6%以上;(2)海捕对虾肌肉中的甜菜碱和氧化三甲胺含量比养殖对虾的高,两者有显著差别;(3)养殖对虾肌肉所含C18:2ω6为17.3±1.5%,海捕对虾为2.0±0.8%。从以上结果本文推荐以脂肪酸C18:2ω6含量来鉴别养殖对虾与海捕对虾。 相似文献
326.
Yang Zhengji Zuo Qihua
Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(2)
The wave forces on 1, 2 and 4 vertical circular piles under the action of several wave trains of the same wave parameters, such as Hs,Tp and Mo, but different wave group factor GF are measured in the laboratory. After comparing these forces, it may be concluded that the mean and significant wave forces are almost of no difference for the wave trains with different GF. When GF is larger, the one-tenth of the wave froce extreme is slightly increased and the maximum wave force is much larger than the ones with smaller GF, to which attention must be paid in engineering practice. 相似文献
327.
The Magellan seamounts began forming as large submarine shield volcanoes south of the equator during the Cretaceous. These
volcanoes formed as a cluster on the small Pacific plate in a period when tectonic stress was absent. Thermal subsidence of
the seafloor led to sinking of these volcanoes and the formation of guyots as the seamounts crossed the equatorial South Pacific
(10–0°S) sequentially and ocean surface temperatures became too high for calcareous organisms to survive. Guyot formation
was completed between about 59 and 45 Ma and the guyots became phosphatized at about 39–34 and 27–21 Ma. Ferromanganese crusts
began formation as proto-crusts on the seamounts and guyots of the Magellan Seamount cluster towards the end of the Cretaceous
up to 55 Ma after the formation of the seamounts themselves. The chemical composition of these crusts evolved over time in
a series of steps in response to changes in global climate and ocean circulation. The great thickness of these crusts (up
to 15–20 cm) reflects their very long period of growth. The high Co contents of the outer parts of the crusts are a consequence
of the increasing deep circulation of the ocean and the resulting deepening of the oxygen minimum zone with time. Growth of
the Co-rich Mn crusts in the Magellan Seamount cluster can be considered to be the culmination of a long journey through time. 相似文献
328.
Ryoko Tokeshi Kaoru Ichikawa Satoshi Fujii Kenji Sato Shoichiro Kojima 《Journal of Oceanography》2007,63(4):711-720
A method to extract geostrophic current in the daily mean HF radar data in the Kuroshio upstream region is established by
comparison with geostrophic velocity determined from the along-track altimetry data. The estimated Ekman current in the HF
velocity is 1.2% (1.5%) and 48° (38°)-clockwise rotated with respect to the daily mean wind in (outside) the Kuroshio. Furthermore,
additional temporal smoothing is found necessary to remove residual ageostrophic currents such as the inertial oscillation.
After removal of the ageostrophic components, the HF geostrophic velocity agrees well with that from the altimetry data with
rms difference 0.14 (0.12) m/s in (outside) the Kuroshio. 相似文献
329.
The origin and biogeochemistry of organic matter in surface sediments of Lake Shihwa and Lake Hwaong
To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic
nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios
for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen (Corg/Norg) (mean = 24) were much higher than ratios of organic carbon to total nitrogen (Corg/Ntot) (mean=12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes.
Stable isotope ratios for organic nitrogen were, on average, 5.2‰ heavier than ratios of inorganic nitrogen in Lake Shihwa,
but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation
of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on
average, 1.4‰ heavier than those for residual organic carbon, reflecting the preferential oxidation of13C-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide
valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments.
This also suggests that the ratio of Corg/Norg and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter. 相似文献
330.
Bin Zhao Yong Yang Gaowen He Heng Zhang Weilin Ma 《Marine Georesources & Geotechnology》2020,38(9):1037-1045
AbstractCobalt-rich crust has attracted increased attention due to their economic value. Studies have indicated that seamounts in the Western Pacific Ocean are rich in cobalt-rich crust resources. The Caiwei Guyot in Western Pacific Ocean is one of the cobalt-rich crust exploration areas contracted between China and the International Seabed Authority. A large volume of research has been conducted to elucidate the tectonic evolution, basement type, sediment type, gravity and magnetic anomaly characteristics, and geochemical characteristics of shallow surface sediments at Caiwei Guyot. However, a research gap exists on the sedimentary strata below the pelagic deposits and above the volcanic basement of the Caiwei Guyot. This paper summarizes that two main types of sediments existing on the top of Caiwei Guyot. The deposition thickness on the top of Caiwei Guyot is characterized by three sedimentary centers and exposed periphery. Pelagic sediments are difficult to form at the northeastern portion and edge area of Caiwei Guyot due to the strong bottom current environment, which makes these areas suitable for crust growth. This paper delineated three cobalt-rich crust prospective areas at the Caiwei Guyot with of significant implications for exploration and mining-lease-block selections at Caiwei Guyot. 相似文献