共查询到20条相似文献，搜索用时 46 毫秒
1.
I~IOWDuceetal.(1980)calculatedthattheair-seaexchangeprocesscouldsupply80%--90%ofthediforedironinputtothephotcrzoneoftheSargassoAsfromairand16%--76%tothecentralNorthPacific.CuisessentialtotheTnarineorganisms,butexcessiveCuistoxictOtheOrganisms.CdandPh... 相似文献
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Gas hydrate saturation from acoustic impedance and resistivity logs in the Shenhu area, South China Sea 总被引：4，自引：0，他引：4
Xiujuan Wang Shiguo Wu Myung LeeYiqun Guo Shengxiong YangJinqiang Liang 《Marine and Petroleum Geology》2011,28(9):1625-1633
During the China’s first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ∼10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. 相似文献
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九孔鲍肠道及其养殖水体中异养细菌产酶能力的分析 总被引：1，自引：0，他引：1
2002年5月从汕尾健生鲍鱼场养殖水体和成鲍肠道中分离筛选到26株异养细菌,其中11株来自成鲍肠道,15株来自养殖水体。对它们产胞外酶的能力进行了比较分析。结果表明肠道异养细菌中有72.7%能分泌蛋白酶、淀粉酶或明胶酶,9.1%分泌脂肪酶,45.5%分泌卵磷脂酶;水体异养细菌中则有46.7%能分泌蛋白酶或脂肪酶,66.7%分泌卵磷脂酶、淀粉酶或明胶酶。比较发现,肠道中脂肪酶或卵磷脂酶生产菌的比例小于水体异养细菌的比例;而蛋白酶、淀粉酶或明胶酶生产菌的比例却高于水体中异养细菌的比例。另外,水体异养细菌分泌多种胞外酶的能力强于肠道异养细菌。由此揭示现有鲍鱼肠道菌群结构的不完善,进而为通过添加有益菌而提高鲍鱼饲料利用率提供了可能。 相似文献
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Ben Ameur W Ben Hassine S Eljarrat E El Megdiche Y Trabelsi S Hammami B Barceló D Driss MR 《Marine environmental research》2011,72(5):258-264
Concentrations of ten polybrominated diphenyl ethers (PBDEs) and eight methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) collected from the Bizerte Lagoon and the Mediterranean Sea were investigated. To the best of our knowledge, this is the first report of these compounds in marine fishes from Tunisia. The PBDE mean concentrations in fish from Bizerte Lagoon were 45.3 and 96.2 ng g(-1) lw respectively in mullet and sea bass, while the concentrations of these compounds in mullet and sea bass from Mediterranean Sea were 7.80 and 27.9 ng g(-1) lw respectively. MeO-PBDE concentrations in mullet and sea bass from Bizerte Lagoon ranged from 6.46 to 286 ng g(-1) lw and from 49.4 to 798 ng g(-1) lw respectively, while the concentrations of these compounds in mullet and sea bass from Mediterranean Sea ranged from 190 to 401 ng g(-1) lw and from 353 to 578 ng g(-1) lw respectively. The total PBDEs and total MeO-PBDEs concentration in fish from Bizerte Lagoon were similar or slightly lower than those reported for other species from other locations around the world. 相似文献
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利用常规观测资料和6 h一次的NCEP 1°×1°再分析场资料对新疆2015年2月12—14日北疆暴雪过程和2015年5月17—21日南疆暴雨过程的环流形势和主要影响系统进行分析,并基于HYSPLIT模式模拟的后向轨迹分析强降水的水汽来源和输送特征。结果表明:1) 2次强降水过程均发生在高空低槽东移,低层有低涡,地面有锋面气旋,高空有辐散的天气背景下。2)冬季暴雪过程中,北疆水汽主要源自西亚和中亚地区。其中源自西亚地区的干气块下沉到近地面时从下垫面获得水汽,对强降雪的贡献最大;其次是起源于中亚西南部地区近地层的湿气块对强降雪的贡献。3)春季暴雨过程中,南疆的水汽主要来自中亚的哈萨克斯坦。其中来自哈萨克斯坦南部上空的干空气下沉到近地层时从下垫面获得水汽,对强降雨的贡献最大;其次是源自哈萨克斯坦东部和东南部对流层低层的湿气块对强降雨的贡献大。4) 2次强降水过程中水汽主要来自陆地而不是海洋,气块在近地层移动或下沉到近地层时,下垫面水汽蒸发使气块变湿,是强降水的水汽主要贡献者;表明春季和冬季的水汽输送通道与夏季来自阿拉伯海等低纬的水汽通道不同。 相似文献
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本文研究了亚丁-欧文-卡尔斯伯格脊(AOC)三联点邻近洋脊的玄武岩样品在主量、微量元素和Pb-Sr-Nd同位素特征上的差异和联系并分析其原因。结果表明,AOC附近卡尔斯伯格脊和希巴洋脊的玄武岩均为正常型洋脊玄武岩(N-MORB),起源自亏损地幔,其中卡尔斯伯格脊的样品较希巴洋脊样品更亏损;欧文洋脊玄武岩样品为洋岛玄武岩(OIB)特征,其地幔源区可能有残余陆块物质的混染;亚丁洋脊玄武岩样品类型包括N-MORB、E-MORB和可能的大陆玄武岩,与洋壳形成过程中大陆岩石圈物质的贡献程度有关。除了卡尔斯伯格脊外,阿法热点对各洋脊的岩浆均有一定程度的影响。 相似文献
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丹江口水库赤眼鳟(Squaliobarbus curriculus)遗传多样性的RAPD和ISSR分析 总被引：1，自引：0，他引：1
利用RAPD和ISSR两种分子标记技术,分析了丹江口水库野生赤眼鳟30个个体的遗传多样性。用11个RAPD引物对其基因组DNA进行扩增,共获得101个重复性好且谱带清晰的扩增位点,片段大小在100—3000bp之间,其中多态性位点63个,多态位点比例为62.38%;个体间遗传距离在0.1049—0.3417之间,平均为0.1742。用10个ISSR引物共检测到88个位点,其中多态性位点61个,多态位点比例为69.32%;个体间遗传距离在0.1088—0.3847之间,平均为0.1907。结果显示,丹江口水库野生赤眼鳟群体的多态位点比例和平均遗传距离均较大,说明其有较高的遗传多样性。 相似文献
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F. J. Taylor 《新西兰海洋与淡水研究杂志》2013,47(2):389-402
Ten samples of freshwater from Campbell Island were analysed for their main ionic constituents. All show a preponderance of sodium and chloride derived from sea water. Potassium, calcium, and magnesium gave slightly higher concentrations than would be expected if derived solely from sea water. It is con‐eluded that the excess potassium is derived from the underlying rocks and soil, and the excess calcium and magnesium from the sea by fractionation into salt particles. 相似文献
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Marine bacteria, actinomycetes and fungal strains were isolated from continental slope sediment of the Bay of Bengal and studied
for fatty acid profile to investigate their involvement in the benthic food-web. Fifteen different saturated and unsaturated
fatty acids from bacterial isolates, 14 from actinomycetes and fungal isolates were detected. The total unsaturated fatty
acids in bacterial isolates ranged from 11.85 to 37.26%, while the saturated fatty acid ranged between 42.34 and 80.74%. In
actinomycetes isolates, total unsaturated fatty acids varied from 27.86 to 38.85% and saturated fatty acids ranged from 35.29
to 51.25%. In fungal isolates unsaturated fatty acids ranged between 44.62 and 65.52% while saturated FA ranged from 20.80
to 46.30%. The higher percentages of unsaturated fatty acids from the microbial isolates are helpful in anticipating the active
participation in the benthic food-web of Bay of Bengal. 相似文献
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Jeffrey N. Cross John T. Hardy Jo Ellen Hose G.Patrick Hershelman Liam D. Antrim Richard W. Gossett Eric A. Crecelius 《Marine environmental research》1987,23(4)
Sea-surface microlayer samples were collected from six nearshore areas receiving different amounts of anthropogenic inputs. The samples were analyzed for selected trace metals, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons. The relative toxicities of the samples were determined with fish embryo bioassays.Contaminant concentrations generally increased from offshore to the inshore stations. Contaminant concentrations were several orders of magnitude higher in microlayer samples from the highly industrialized Los Angeles and Long Beach harbors compared to samples from a site 15km offshore. Microlayer samples from the inshore stations were significantly more toxic, and induced significantly more developmental abnormalities and chromosome aberrations, than samples from the offshore stations. 相似文献
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Balasubramanaian Thilagavathi Bandana Das Ayyappan Saravanakumar Kuzhanthaivel Raja 《Ocean Science Journal》2011,46(2):63-72
The ecological aspects of meiofaunal communities in the Muthupettai mangrove forest, East coast of India, has not been investigated
in the last two decades. Surface water temperature ranged from 23.5 °C to 31.8 °C. Salinity varied from 24 to 34 ppt, while
water pH fluctuated from 7.4 to 8.3. Dissolved oxygen concentration ranged from 3.86 to 5.33 mg/l. Meiofauna analysis in this
study identified a total of 106 species from the mangrove and adjacent open sea area of Sethukuda. Among these, 56 species
of foraminiferans, 20 species of nematodes, 7 species of harpacticoid copepods, 4 species of ostrocodes, and 2 species of
rotifers were identified. Furthermore, a single species was identified from the following groups: ciliophora, cnidaria, gnathostomulida,
insecta, propulida, bryozoa and polychaete larvae. Meiofaunal density varied between 12029 to 23493 individuals 10 cm/m2. The diversity index ranged from 3.515 to 3.680, species richness index varied from 6.384 to 8.497, and evenness index varied
from 0.839 to 0876 in the mangrove area and adjacent open sea. 相似文献
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This geochemical survey defines the typical features of representative oils from the major Colombian basins, and proposes a classification scheme useful for hydrocarbon exploration. This work is based on properties of whole oils such as API gravity, sulfur, vanadium and nickel concentrations, and gas chromatography fingerprints. The framework is completed by inclusion of biomarker parameters derived from GCMS and GCMSMS analysis.Oils from the basins of the Middle Magdalena Valley, Upper Magdalena Valley, Sinú - San Jacinto, Putumayo-Caguan, Lower Magdalena Valley and Catatumbo were assessed. Conclusions were drawn regarding possible sources of origin, oil families, degree of thermal evolution, biodegradation, mixing and refreshing, and inferences regarding exploration implications.The oils from the Middle Magdalena Valley and Upper Magdalena Valley (intermontane basins) and Putumayo (foreland basin), except those from the Caguan area, are oils with similar characteristics. In these three cases the oils are probably coming from source rocks intervals deposited in a marine Cretaceous platform, with variable carbonate/siliciclastic features. In these basins there are no oils derived from Tertiary source rocks.In Sinú-San Jacinto and Lower Magdalena Valley basins the main proportions of oils comes from very proximal environments, probably deltaic type, of Tertiary age with a minor proportion of oils coming from Cretaceous source rocks of marine anoxic environment (the only marine Cretaceous oils discovered so far in the Sinú-San Jacinto and Lower Magdalena Valley basins).The oils from Eastern Foothills of the Eastern Cordillera, look to be derived mainly from proximal Cretaceous source rocks with some mixing of oils derived from Tertiary strata. In the Catatumbo basin there are oils derived mainly from Cretaceous source rocks and some from Tertiary source rocks.Regarding the processes after entrapment, in all of the basins, the biodegradation effects were observed in varying degrees. These processes are dominant toward more quiescent regions, beyond the areas with more tectonic activity, far from the foothills of the Eastern Cordillera. Instead, close to the Eastern Cordillera are more common the paleobiodegradation processes due to reburial of younger molasses. The effects of mixing or refreshing are remarkable close to the Eastern Cordillera foothills in Llanos, Middle Magdalena Valley, and Upper Magdalena Valley basins. 相似文献
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We examined spatial variability in meristic and morphological characteristics of the branchial basket of sardine Sardinops sagax collected from four geographical regions around the southern African coast, namely Namibia and the South African west, south and east coasts. Our analysis tested the hypothesis of three putative sardine stocks off South Africa, one in each of the three geographical regions. We therefore collected fish data from Namibia to compare with South Africa, because sardine from the two countries are considered to be separate stocks. Morphometric measurements (gill arch length and gill raker spacing) and meristic data (number of gill rakers) were collected from the left side of the first gill arch from a total of 377 sardine, approximately equally divided between the regions. A multivariate general linear model with caudal length as covariate was used to assess differences among fish from the four regions and significant differences were observed, although not always consistently across all fish size classes. Small South Coast sardine had shorter gill arches than small West Coast sardine, but adults had gill arches of similar length, longer than those from Namibia and the East Coast. Small sardine from the South Coast had fewer gill rakers than small sardine from the West Coast, but larger fish had similar numbers of gill rakers, significantly more than sardine from Namibia and the East Coast. Sardine from the West and South coasts had similar gill raker spacings, which were smaller than those of fish from the East Coast and Namibia. Despite spatially and particularly temporally unbalanced sampling, we consider that these differences provide evidence of spatial variation in Benguela sardine phenotype and that it would support the hypothesis of discrete sardine stocks off Namibia and South Africa. The results are consistent with the hypothesis of three sardine stocks within the southern Benguela. 相似文献
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长江口北支盐水倒灌南支对青草沙水源地的影响 总被引：13，自引：1，他引：13
自1978年以来，在长江口的几个关键岸段（例青龙港、新建、高桥、堡镇等）设置盐度观测站；1992－1994年的枯季、在青草沙水源地的南、北两侧各抛测量船一般，在一个完整的大、中、小潮期间、连续逐时观测流速、流向、水深、盐度等，同时在青龙港等处设置6个岸边观测点同步取样；1995－1996年在船站位置各设置氯离子自动监测仪一台；1996年3月又进行了一次大规模的长江口水文测验。本文对大量的现场资料作了分析计算。研究结果表明，青草沙水源地盐水来源主要有北支倒灌咸水团和外海咸水入侵。前者的特征为，氯度的半月变化是小潮期（或小潮后的寻常潮）的氯度反高于大潮期，氯度的潮周日变化是日最高值出现在落憩附近，日最低值出现在涨憩附近，氯度的垂向分层不明显。这与外海盐水入侵引起的氯离子浓度在半月和潮周日内的变化特征正好相反。 相似文献
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海洋链霉菌由于其独特的生理和代谢功能,成为海洋微生物活性物质的主要来源。对2010-2013年初的海洋放线菌天然产物的统计表明,研究最多的是链霉菌放线菌,占海洋放线菌新天然产物的60%。本文综述了自1976年第一个海洋链霉菌天然产物到2016年6月的40年间报道的547个海洋链霉菌天然产物的结构、生物活性及其微生物来源。其结构包括含氮化合物（如生物碱）、聚酮、萜类、甾体等,其中含氮化合物是主要类型, 占海洋链霉菌天然产物总数的61%;而67%的海洋链霉菌天然产物表现出细胞毒、抑菌、抗疟和抗寄生虫等生物活性。 相似文献
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Melanie Summit John A. Baross 《Deep Sea Research Part II: Topical Studies in Oceanography》1998,45(12):2751-2766
High-temperature microbes were present in two hydrothermal event plumes (EP96A and B) resulting from the February–March 1996 eruptions along the North Gorda Ridge. Anaerobic thermophiles were cultured from 17 of 22 plume samples at levels exceeding 200 organisms per liter; no thermophiles were cultured from any of 12 samples of background seawater. As these microorganisms grow at temperatures of 50–90°C, they could not have grown in the event plume and instead most probably derived from a subseafloor environment tapped by the event plume source fluids. Event plumes are thought to derive from a pre-existing subseafloor fluid reservoir, which implies that these thermophiles are members of a native subseafloor community that was present before the eruptive event. Thermophiles also were cultured from continuous chronic-style hydrothermal plumes in April 1996; these plumes may have formed from cooling lava piles. To better understand the nutritional, chemical, and physical constraints of pre-eruptive crustal environments, seven coccoidal isolates from the two event plumes were partially characterized. Results from nutritional and phylogenetic studies indicate that these thermophiles are heterotrophic archaea that represent new species, and probably a new genus, within the Thermococcales. 相似文献
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In this study an attempt has been made to extract sediment geoacoustic properties using ambient noise measured from a vertical hydrophone array. Time series noise data recorded from three shallow water sites (Chennai, Cuddalore and Cochin) along the Indian continental shelf were used for the analysis. The compressional sound speed of sediment for all the sites was estimated from the vertical directionality of ambient noise. Using the value of the compressional sound speed remaining wave properties and material properties were deduced from the Grain-Shearing (G-S) theory of wave propagation in saturated granular media. The type of sediment extracted from the G-S theory correlates well with the results obtained from sieve and particle size analysis of grab samples, collected from all the sites. The study clearly shows the application of ambient noise in extracting environmental information in shallow water, and further applying it to improve sonar performance modeling. 相似文献