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1.
Microbial diversity in the abyssal sediments beneath the seafloor of 30, 94, and 151 cm near the southern end of the Mariana Trench was analyzed in the Illumina HiSeq 2500 platform. Results show that the microbial populations were dominated by bacteria but merely no archaea were identified at the three depths. In the bacterial community,Proteobacteria and Firmicutes dominated the total taxon tags, followed by Bacteroidetes, Actinobacteria, Planctomycetes, Cyanobacteria, and Chloroflexi, which together account for over 99% of the total population. Similar to that in the seawater in the trench, the operational taxonomic units(OTUs) belonging to Gammaproteobacteria from the sediment samples showed high abundance.However, common bacterial OTUs in the water of the trench including Nitrospirae and Marinimicrobia were hardly found in the sediments from the southern Mariana Trench or the hadal region. Therefore, this study documented for the first time the compositions of microbial diversity in the trench sediments, revealed the difference in microbial diversity in water and sediment of the trench and will enrich the knowledge on the microbial diversity in the abyssal areas. 相似文献
2.
Niu Jiaohong Sun Chengjun Yang Bo Xie Lei Jiang Fenghua Cao Wei Chen Yan Ding Haibing Huang Yuhuan Gao Xianchi 《中国海洋湖沼学报》2023,41(1):118-137
The composition and concentration of dissolved free amino acid (DFAA) of seawater samples collected in May 2016 from the surface to the hadal zone of the northern region of the Yap Trench were analyzed by pre-column derivatization of o-phthalaldehyde. Results show that the average concentration of DFAA in the study area was 0.47±0.36 µmol/L. In different sampling stations, the concentrations of DFAA with water depth showed complex variation patterns. At the sediment-seawater interface, the concentrations of DFAA in the western side of the trench were obviously higher than that in its eastern side. In the study area, there were no significant correlations between the concentrations of DFAA and the environmental parameters such as concentrations of chlorophyll a (Chl a), dissolved oxygen (DO), pH, and dissolved inorganic nitrogen (DIN), indicating that the concentrations of DFAA in seawater of the trench are affected by many factors, such as photosynthesis, respiration, temperature, pressure, illumination, and circulation. The dominant DFAA are similar in different water layers of sampling stations, including aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), and serine (Ser). The composition of different amino acids, and the relative abundance of acidic, basic, and neutral amino acids might be related to the sources and consumption of various amino acids. Nine pairs of amino acids in the DFAA showed significantly positive relationship by correlation matrix analysis, suggesting that they might share similar biogeochemical processes. The degradation index (DI) of the DFAA in seawater of the Yap Trench could reflect the degradation, source, and freshness of DFAA in the trench to some extents. This is a preliminary study of amino acids from sea surface to hadal zone in the ocean, more works shall be done in different trenches to reveal their biogeochemical characteristics in extreme marine environments.
相似文献3.
Huang Yuhuan Sun Chengjun Yang Guipeng Yue Xin&#;an Jiang Fenghua Cao Wei Yin Xiaofei Guo Chaonan Niu Jiaohong Ding Haibing 《中国海洋湖沼学报》2020,38(3):650-664
Journal of Oceanology and Limnology - Two sediment cores were retrieved in the hadal zone of the Yap Trench, and their concentrations of six major elements Mg, Al, Ca, Ti, Mn and Fe and nine trace... 相似文献
4.
Yixin Yan Chengjun Sun Yuhuan Huang Wei Cao Fenghua Jiang Guipeng Yang Haibing Ding 《中国海洋湖沼学报》2020,38(3):634-649
In this study, cored sediment samples collected by the Jiaolong Submersible at 6 779 m depth from the hadal zone of the Yap Trench in May 2016 were sliced in 1-cm interval from top to bottom, and lipids in each sediment layer were quantitatively and qualitatively analyzed. The vertical distribution profiles of the lipids in the sediment sample, their main existing forms, and their possible sources were investigated. The results show that the concentration of lipid in the surface sediment was the highest with the carbon number from 12 to 27, dominated by medium and short-chain lipids. The total concentration of fatty acids in surface sediment was much higher than those in the offshore and deep-sea areas, being up to 325.77 μg/g due to the funnel effect caused by the “V” terrain of the trench. Fatty acid 18.0 was the most abundant lipids in the sediment sample. Abnormal high concentrations of fatty acid 18.ω7 and alkanes indicated the existence of hydrothermal fluids in the study area. In addition, saturated fatty acids and monounsaturated fatty acids existed mainly in free form, and polyunsaturated fatty acids existed mainly in bound form. Most of the alkanes were in bound form, and their major source was autochthounous input. The carbon number of alcohols in the sediment sample ranged from 12 to 20, mainly existed in bound form. The source of fatty acids was mainly autochthonous input, and the neutral lipids had both marine and terrestrial origin. This is the first study of lipids in hadal sediment of the Yap Trench. The results will promote deeper understanding of organic carbon cycle in marine environment. 相似文献
5.
The abyssal circulation in the Philippine Sea(PS)is investigated,with outputs from the Simple Ocean Data Assimilation version 2.2.4(SODA224).The deep-water currents in SODA224 are carefully evaluated,with sparse in situ observations in the North Pacific Ocean.In the upper deep layer(20003000 m)of the PS,a strong westward current,which originates from the Northeast Pacific Basin and enters the PS through the Yap-Mariana Junction,exists along 1114 N.This strong westward current bifurcates into two western boundary currents off the Philippines.The northward-flowing current flows out of the PS around 2021 N,whereas the southward-flowing current transports deep water from the northern hemisphere to the southern hemisphere.In the lower deep layer(30004500 m),the inflow water first flows northward to the east of the Western Mariana Basin and then turns westward at approximately 18 N.The inflow water mainly enters the Philippine Basin(PB),with a small part turning southward to constitute a weak cyclonic circulation.The water entering the PB mainly merges into a strong southward western boundary current in the south-ern PB.In the bottom layer(below 4500 m),both the northeast and northwest PB show single cyclonic gyres,whereas the south PB shows a single anticyclonic gyre.Moreover,comparisons with the observations indicate the possible existence of a cyclonic sense of circulation over the Philippine Trench.The current study provides the implications for future observations,which are needed to fur-ther investigate the temporospatial variations of the abyssal circulation in the PS on multiple scales. 相似文献
6.
Measured concentrations of dissolved oxygen, phosphate, silicate, total alkalinity and calculated total CO2 in a section between 121° E and 125° E across the Kuroshio near 22° N off Taiwan and the geostrophic velocity were used to
estimate the gross transport of oxygen, nutrients and carbonates.
The flux of dissolved oxygen is 6.7×106 mol/s northward and 0.9×106 mol/s southward. The net flux equals 5.8×106 mol/s down-stream. The northward flux of phosphate is 22.6×103 mol/s; the southward flux is 1.4×103 mol/s. The net phosphate flux is 21.2×103 mol/s northward. The flux of silicate is 967×103 northward and 59×103 mol/s southward; the net transport is 908×103 mol/s down-stream. The flux of alkalinity is 75.5×106 mol/s northward, and 10.8×106 mol/s southward, the net flux is 64.7×106 mol/s northward. For total CO2 the transport is 73.4×106 mol/s northward and 10.8×106 mol/s southward, or a net transport of 62.6×106 mol/s horthward. 相似文献
7.
Using merged sea level anomaly and absolute geostrophic velocity products from satellite altimetry and Argos drifter data,we analyzed the reversal process of the South China Sea(SCS) western boundary current(SCSwbc) from a summer to winter pattern in 2011 and important oceanic phenomena during this process.Results show that the outbreak time of the northeast monsoon over the southern SCS lagged that over the northern SCS by about 1 month.During the SCS monsoon reversal period,the SCSwbc reversed rapidly into the winter pattern at the Guangdong continental slope in late September.Subsequently,the southward Vietnam coastal boundary current strengthened.However,the northward Natuna Current maintained a summer state until mid-October.Thus,the balance between the southward and northward currents was lost when they met,their junction moved gradually southward.However,a loop current formed southeast of Vietnam because the main stream of the Vietnam Offshore Current(VOC) remained near its original latitude.Meanwhile,the VOC and associated dipole circulation system strengthened.After midOctober,the northward Natuna Current began to weaken,the loop current finally shed,becoming a cool ring.The VOC and its associated dipole sub-basin circulation system also weakened gradually until it disappeared. 相似文献
8.
We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958–2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell (TC), Subtropical Cell (STC), and Deep Tropical Cell (DTC) may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO (El Niño-Southern Oscillation). The TC northward, southward, upward, and downward transports all weaken in El Niños and strengthen in La Niñas. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the tropics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong El Niños and increase during strong La Niñas. DTC upward and downward transports are not strongly correlated with the Niño-3 index and may not be completely controlled by ENSO. 相似文献
9.
Jiang Zuzhou Sun Zhilei Liu Zhaoqing Cao Hong Geng Wei Xu Haixia Wang Lisheng Wang Libo 《中国海洋湖沼学报》2019,37(3):998-1009
The hadal zone represents one of the last great frontiers in modern marine science, and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question. Here, we examine the mineralogical and geochemical composition of a sediment core(core CD-1) that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench. Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris. We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging ～72%). The remainder, however, is supplied by aeolian dust(averaging ～28%), which is consistent with adjacent studies that utilized Sr-Nd isotopic data. Building on a growing database, we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific, which ultimately improves our appreciation of sedimentation in, and around, the hadal zone. 相似文献
10.
Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport (MHT) and meridional salt transport (MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents (WBCs) are estimated for the first time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacific. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area. 相似文献
11.
In this paper, the linear continuously stratified ntxiel of the abyssal circulation proposed by Pedlosky (1992) was emended to include the second order term - (γθm) in the vertical turbulent mixing pararneterization of - (ω‘θ‘）x = kvθxx- θxxx, in which kv is a vertical diffusion coefficient,and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ＜0 is only allcmed). The influence of the γ-tema on the baroclinic structure of the abyssal circulation driven by up-welling out of the abyss was investigated, It was found that the γ-term has a noticeable influence on thebaroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroelinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in thewest. In addition, this parameter was found to decrease the vertically averaging meridional velocity of theabyssal circulation frcrn the west to the east on the southern boundary. For upwelling localized near theeastern boundary, the γ - term favors baroclinic layering of the abyssal circulation in the whole basin.Especially, on the southern boundary the γ - term could strengthen the vertically averaging meridional ve-loeity in the west, but gready weaken it in the east. The ntntel presented here might be considered as anextension of the Pedlosky baroclinic ntntel of the abyssal circulation. 相似文献
12.
Interannual variability of transport and bifurcation of the North Equatorial Current in the tropical North Pacific Ocean 总被引：1，自引：0，他引：1
The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current (NEC) to the El Ni o-Southern Oscillation (ENSO) is investigated. This is done through composite analysis of sea surface height (SSH) observed by satellite altimeter during October 1992-July 2009, and correspondingly derived sea surface geostrophic currents. During El Nio/La Ni a years, the SSH in the tropical North Pacific Ocean falls/rises, with maximum changes in the region 0-15°N, 130°E-160°E. The decrease/increase in SSH induces a cyclonic/anticyclonic anomaly in the western tropical gyre. The cyclonic/anticyclonic anomaly in the gyre results in an increase/decrease of NEC transport, and a northward/southward shift of the NEC bifurcation latitude near the Philippine coast. The variations are mainly in response to anomalous wind forcing in the west-central tropical North Pacific Ocean, related to ENSO events. 相似文献
13.
Guan Bingxian 《中国海洋湖沼学报》1990,8(2):167-176
The deep water (1000–3000 m) circulation in the area east of Taiwan and the Philippines has been little studied. Moriyasu
(1972) and Reid (1981) discussed the 3000 db surface (3000/1200 db) and 2000 db surface (2000/3500 db) circulations of the
Philippine Sea Basin, respectively. They both showed that there may be a northward current close to the western margin of
the Sea Basin. Recent analyses of two sets of deep sea hydrographic data yielded quite different results, i. e., at deep waters
in the area east of Taiwan and the Philippines southward countercurrents flow under the upper northward currents.
The possible causative mechanism of these southward deep countercurrents is the blocking effects of the submarine ridge east
of Suao and of the Ryukyu Islands Shelf on the northward flowing upper currents.
The above-mentioned preliminary deductions were wholely based on consideration of the relative geostrophic current and calculation,
though the reference surface (3500 db) was very deep. It is suggested that direct measurements of the deep currents in the
study area are needed to verify these results.
Contribution No. 1750 from the Institute of Oceanology, Academia Sinica. This paper was presented at the PRC/USA Symposium
on Western Pacific Air-Sea Interaction (Nov., 1988, Beijing). This project was supported by the National Natural Science Foundation
of China. 相似文献
14.
INTRODUCTIONIntheearly 1 980 s,ventilationtheoryemergedtopredictthehorizontalandverticalstructureofthethermocline.Thereweretwodifferentviewsonthestratifiedoceans.Thefirsttheory (RhinesandYoung,1 982 ,hereafterRY ;YoungandRhines,1 982 )proposedanunventilatedmodelinwhichonlytheuppermostlayerisexposedtothesurfaceandisforcedbythewindstress.Thesecondtheory (Luytenetal.,1 983 ,hereafterLPS)offeredaventilatedmodelwhichisclosertotheclassicalthermoclinetheoriesthanthatofthefirstone (e.g .,Nee… 相似文献
15.
海底地震引发的海啸灾害,对沿海国家和地区的影响是相关领域的研究热点。研究采用COMCOT海啸数值模拟模型,对可能发生在马尼拉海沟一次地震活动（Mw=9.0级）所引起的海啸过程进行了数值模拟,并研究了该海啸传播到海南岛和北部湾的过程及其特点,分析海啸波对这一地区可能造成的影响。研究发现,传播到北部湾地区的海啸波具有明显的非线性特征,海啸发生后2 h 10 min左右到达海南岛东海岸,首轮波高达2.1 m;随着湾内水深逐渐变浅,受制于海底摩阻,及海南岛的阻隔与缓冲作用,海啸到达广西壮族自治区南部沿海地区的时间,被推迟到距地震发生8 h后,海啸波高减小到0.4 m,海啸波能量大为衰减。研究结果表明,马尼拉海沟地震引发海啸,对海南岛东南部沿海影响较大,有成灾的可能性;而对广西壮族自治区南部沿海及北部湾地区的影响较弱,一般不会造成大的灾害。 相似文献
16.
Scattering Process of Internal Waves Propagating over a Subcritical Strait Slope onto a Shelf Region
DAI Dejun WANG Wei QIAO Fangli YUAN Yeli 《中国海洋大学学报(英文版)》2005,4(4):377-382
The scattering process, which means the redistribution of energy fluy in modenumber space, is analyzed for internal waves propagating from the abyssal ocean onto a subcritical strait slope and then a shelf region. In light of Wunsch＇s work, the waves are analytically expressed as superimposition of eigensolutions distribution of energy flux in the shelf region： one is the ratio of water depth in and the other is the ratio of the slope of the internal tide rays to the topographic energy flux distribution： the energy flux is focused around one modenumber or case, the range of modenumbers where energy flux is distributed is narrow. Two parameters have evident effects on the the shelf region to that in the abyssal ocean slope. Generally, there are two patterns of focused around two modenumbers. In any case, the range of modenumbers where energy flux is distributed is narrow. 相似文献
17.
The Ryukyu trench-arc system can be divided into two types according to its subduction model. The normal subduction in the
northern part of the Philippine Sea plate creates a hinge sedimentary wedge with large deformation at the collision front,
while the oblique subduction in the southern part gives rise to a smaller accretion with small deformation than that in the
northern part. The mechanisms that cause distinction between these two types have been analysed and calculated by using gravity
data based on the lithosphere rheology and the stress state of the lithosphere in the subduction boundary. The two types of
subduction model are associated with the internal extension in the southern Okinawa Trough and the small extension in the
northern part. The difference of the stress state between the two types of subduction model is also manifested in other tectonic
features, such as topography, volcanic activity and crust movement. Modeling bathymetric and gravity data from this area suggests
that the oblique subduction of low angle, together with smooth geometry of the overlying plate crust, results in small stress
released on the south of the trench by the subduction plate. The intraplate faults in the southern Okinawa Trough behind the
trench stand in surplus intensive stress. On the other hand, the normal subduction of high angle, together with strong undulation
geometry of the overlying crust, results in more intensive stress released in the northern Ryukyu Trench than that in the
south. The intraplate faults in the northern Okinawa Trough behind the northern Ryukyu Trench stand in small stress. 相似文献
18.
南三河沉管是鉴江供水枢纽工程中的一处跨海管道工程,管道基槽开挖会对周围海域水质产生影响。基于建立的二维非稳态水环境数学模型,利用同步水文水质监测数据对模型参数进行率定,并反演得到SS源强浓度,继而预测施工期SS对海域水环境的影响范围及程度。结果表明:距基槽中心50 m范围的SS源强浓度达到70 mg/L;SS会对基槽中心线上下游各700 m范围内的水域产生影响(增量≥10 mg/L),影响程度以挖槽为中心线向两侧递减。 相似文献
19.
Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015 总被引：1，自引：0，他引：1
Denghui Li Meng Zhou Zhaoru Zhang Yisen Zhong Yiwu Zhu Chenghao Yang Mingquan Xu Dongfeng Xu Ziyuan Hu 《中国海洋大学学报(英文版)》2018,17(3):477-486
The northern slope region of the South China Sea(SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by cross-shelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55-m water masses on the SCS northern slope and thereby elucidate the cross-slope transport of shelf water(SHW) and the intrusions of Kuroshio water(KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water(SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong cross-slope current with speeds greater than 50 cms~(-1) to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area. 相似文献
20.
Pu Yongxiu 《中国海洋湖沼学报》1987,5(2):186-193
Every year during late spring and summer, a patch of surface cold water exists near the eastern side of the Subei shoal patch.
The main cause of the cold water is the monthly southward migration and climbing up of the deep cold water from the western
part of the southern Huanghai Sea. The existence of the deep ditches on the north side of the underwater delta off Subei controls
the position of this cold water.
Another patch of cold water is commonly observed southwest of Jizhou Island on the surface in the region 32oN and 124o–124.5oE during late spring and summer. Based on analysis, this water comes mainly from the deep layers of the northwest area; its
upwelling is related to the northward “impulsive” extension of the Taiwan Warm Current in the previous period, and its position
is probably related to the underwater reef chain there. 相似文献