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Lateral downslope transport and tentative sedimentary organic carbon box model in the southern Yap Trench,western Pacific Ocean

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Acta Oceanologica Sinica 2023年第1期42卷 61-74页

作者： Dong Li Jun Zhao Chenggang Liu Jianming Pan Ji Hu Key Laboratory of Marine Ecosystem Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China

Sediment collapse and subsequent lateral downslope migration play important roles in shaping the habitats and regulating sedimentary organic carbon(SOC)cycling in hadal trenches.In this study,three sediment cores were collected using a human-occupied vehicle across the axis of the southern Yap Trench(SYT).The total organic carbon(TOC)and total nitrogen(TN)contents,δ13C,radiocarbon ages,specific surface areas,and grain size compositions of sediments from three cores were measured.We explored the influence of the lateral downslope transport on the dispersal of the sediments and established a tentative box model for the SOC balance.In the SYT,the surface TOC content decreased with water depth and was decoupled by the funneling effect of the V-shaped hadal trench.However,the sedimentation(0.0025 cm/a)and SOC accumulation rates(∼0.038 g/(m^(2)·a)(in terms of OC))were approximately 50%higher in the deeper hadal region than in the abyssal region(0.0016 cm/a and∼0.026 g/(m^(2)·a)(in terms of OC),respectively),indicating the occurrence of lateral downslope transport.The fluctuating variations in the prokaryotic abundances and the SOC accumulation rate suggest the periodic input of surficial sediments from the shallow region.The similar average TOC(0.31%–0.38%),TN(0.06%–0.07%)contents,and SOC compositions(terrestrial OC(11%–18%),marine phytoplanktonic OC(45%–53%),and microbial OC(32%–44%))of the three sites indicate that the lateral downslope transport has a significant mixing effect on the SOC composition.The output fluxes of the laterally transported SOC(0.44–0.56 g/(m^(2)·a)(in terms of OC))contributed approximately(47%–73%)of the total SOC input,and this proportion increased with water depth.The results of this study demonstrate the importance of lateral downslope transport in the spatial distribution and development of biomes.

关键词： southern Yap Trench sedimentary organic carbon cycling lateral downslope transport diluting effect box model

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The decomposition rate of the organic carbon content of suspended particulate matter in the tropical seagrass meadows

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Acta Oceanologica Sinica 2021年第8期40卷 44-52页

作者： A'an Johan Wahyudi Karlina Triana Afdal Afdal Hanif Budi Prayitno Edwards Taufiqurrahman Hanny Meirinawati Rachma Puspitasari Lestari Lestari Suci Lastrini Research Center for oceanography Indonesian Institute of Sciences(LIPI)Jakarta 14430Indonesia

In terms of downward transport,suspended particulate matter(SPM)from marine or terrigenous sources is an essential contributor to the carbon cycle.Within mesoscale environments such as seagrass ecosystems,SPM flux is an essential part of the total carbon budget that is transported within the ecosystem.By assessing the total SPM transport from water column to sediment,potential carbon burial can be estimated.However,SPM may decompose or reforming aggregate during transport,so estimating the vertical flux without knowing the decomposition rate will lead to over-or underestimation of the total carbon budget.Here this paper presents the potential decomposition rate of the SPM in seagrass ecosystems in an attempt to elucidate the carbon dynamics of SPM.SPM was collected from the seagrass ecosystems located at Sikka and Sorong in Indonesia.In situ experiments using SPM traps were conducted to assess the vertical downward flux and decomposition rate of SPM.The isotopic profile of SPM was measured together with organic carbon and total nitrogen content.The results show that SPM was transported to the bottom of the seagrass ecosystem at a rate of up to(129.45±53.79)mg/(m^(2)·h)(according to carbon).Considering the whole period of inundation of seagrass meadows,SPM downward flux reached a maximum of 3096 mg/(m^(2)·d)(according to carbon).The decomposition rate was estimated at from 5.9μg/(mg·d)(according to carbon)to 26.6μg/(mg·d)(according to carbon).Considering the total downward flux of SPM in the study site,the maximum decomposed SPM was estimated 39.9 mg/(m^(2)·d)(according to carbon)and 82.6 mg/(m^(2)·d)(according to carbon)for study site at Sorong and Sikka,respectively.The decomposed SPM can be 0.6%–2.7%of the total SPM flux,indicating that it is a small proportion of the total flux.The seagrass ecosystems of Sorong and Sikka SPM show an autochthonous tendency with the primary composition of marine-end materials.

关键词： carbon dynamic biogeochemistry coastal ecosystem particulate matter

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Geostrophic Spirals Generated by the Horizontal Diffusion of Vortex Stretching in the Yellow Sea

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Advances in Atmospheric Sciences 2019年第2期36卷 219-230页

作者： Xiangzhou SONG Rui Xin HUANG Dexing WU Fangli QIAO Guansuo WANG Physical oceanography Laboratory Ocean University of China State Oceanic Administration Ministry of Natural Resources Department of Physical oceanography Woods Hole Oceanographic Institution First Institute of Oceanography State Oceanic Administration

Horizontal velocity spirals with a clockwise rotation(downward looking) rate of 1.7?m^(-1), on average, were observed in the western and northern Yellow Sea from December 2006 to February 2007. With the observed thermal wind relation,the beta-spiral theory was used to explain the dynamics of spirals. It was found that the horizontal diffusion of geostrophic vortex stretching is likely to be a major mechanism for generating geostrophic spirals. Vertical advection associated with surface/bottom Ekman pumping and topography-induced upwelling is too weak to support these spirals. Strong wind stirring and large heat loss in wintertime lead to weak stratification and diminish the effects of vertical advection. The cooling effect and vertical diffusion are offset by an overwhelming contribution of horizontal diffusion in connection with vortex stretching. The Richardson number-dependent vertical eddy diffusivity reaches a magnitude of 10^(-4) m^2 s^(-1) on average. An eddy diffusivity of 2870 m^2 s^(-1) is required for dynamic balance by estimating the residual term. This obtained value of 10-4 m^2 s^(-1) is in good agreement with the estimation in terms of observed eddy activities. The suppressed and unsuppressed diffusivities in the observation region are 2752 and 2881 m^2 s^(-1), respectively, which supports a closed budget for velocity rotation.

关键词： geostrophic spirals horizontal diffusion vortex stretching and surface cooling effect

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Microearthquake reveals the lithospheric structure at midocean ridges and oceanic transform faults

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Journal of Oceanology and Limnology 2024年第3期42卷 697-700页

作者： Zhiteng YU Jiabiao LI Weiwei DING Key Laboratory of Submarine Geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly understood.The large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic lithosphere.Previous studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃isotherm.However,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform faults.Several mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.

关键词： microearthquake mid-ocean ridge oceanic transform fault oceanic lithosphere thermal structure earthquake location

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Analysis of multi-dimensional SAR for determining the thickness of thin sea ice in the Bohai Sea

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Chinese Journal of Oceanology and Limnology 2013年第3期31卷 681-698页

作者：张晰张杰孟俊敏苏腾飞 The First Institute of Oceanography State Oceanic Administration

Flat thin ice (<30 cm thick) is a common ice type in the Bohai Sea, China. Ice thickness detection is important to offshore exploration and marine transport in winter. Synthetic aperture radar (SAR) can be used to acquire sea ice data in all weather conditions, and it is a useful tool for monitoring sea ice conditions. In this paper, we combine a multi-layered sea ice electromagnetic (EM) scattering model with a sea ice thermodynamic model to assess the determination of the thickness of flat thin ice in the Bohai Sea using SAR at different frequencies, polarization, and incidence angles. Our modeling studies suggest that co-polarization backscattering coefficients and the co-polarized ratio can be used to retrieve the thickness of flat thin ice from C- and X-band SAR, while the co-polarized correlation coefficient can be used to retrieve flat thin ice thickness from L-, C-, and X-band SAR. Importantly, small or moderate incidence angles should be chosen to avoid the effect of speckle noise.

关键词：渤海海冰厚度检测 SAR 多维合成孔径雷达后向散射系数热力学模型极化比

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Statistical Analysis of Thunderstorms on the Eastern Tibetan Plateau Based on Modified Thunderstorm Indices

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Advances in Atmospheric Sciences 2015年第4期32卷 515-527页

作者： YOU Wei ZANG Zengliang PAN Xiaobin ZHANG Lifeng LI Yi institute of Meteorology and oceanography PLA University of Science and Technology

The Tibetan Plateau, with an average altitude above 4000 m, is the highest and largest plateau in the world. The frequency of thunderstorms in this region is extremely high. Many indices are used in operational forecasting to assess the stability of the atmosphere and predict the probability of severe thunderstorm development. One of the disadvantages of many of these indices is that they are mainly based on observations from plains. However, considering the Plateau＇s high elevation, most convective parameters cannot be applied directly, or their application is ineffective. The pre-convective environment on thunderstorm days in this region is investigated based on sounding data obtained throughout a five-year period（2006–10）.Thunderstorms occur over the Tibetan Plateau under conditions that differ strikingly from those in plains. On this basis,stability indices, such as the Showalter index（including SI and SICCL）, and the K index are improved to better assess the thunderstorm environments on the Plateau. Verification parameters, such as the true-skill statistic（TSS） and Heidke skill score（HSS）, are adopted to evaluate the optimal thresholds and relative forecast skill for each modified index. Lastly, the modified indices are verified with a two-year independent dataset（2011–12）, showing satisfactory results for the modified indices. For determining whether or not a thunderstorm day is likely to occur, we recommend the modified SICCLindex.

关键词： thunderstorm,Tibetan Plateau,modified parameters,skill score

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Petrology and geochemistry of cold seep carbonates from the northern Okinawa Trough,East China Sea:implications to early diagenesis

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Journal of Oceanology and Limnology 2022年第4期40卷 1388-1403页

作者： Kehong YANG Zhimin ZHU Yanhui DONG Weiyan ZHANG Fengyou CHU Key Laboratory of Submarine Geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

Carbonate samples were collected from the northern Okinawa Trough in the East China Sea in 2013.The petrology,mineralogy,carbon and oxygen isotopes,and rare earth elements(REEs)of these samples were analyzed.Aragonite,high-Mg calcite,and dolomite were the main carbonate minerals,the contents of which varied greatly among the carbonate samples.Petrological observations revealed the common occurrence of framboidal pyrites.Theδ^(13)C values of carbonates varied from-53.7‰to-39.3‰(average of-47.3‰based on Vienna Pee Dee Belemnite(V-PDB),n=9),and theδ^(18)O values ranged from 0.6‰to 3.4‰(average of 1.9‰;V-PDB,n=9).The carbon and oxygen isotope characteristics indicated that the carbonates precipitated during the anaerobic oxidation of methane.The carbon source was a mixture of thermogenic methane and biogenic methane,possibly with a greater contribution from the former.The oxygen isotope data showed that gas hydrate dissociation occurred during carbonate precipitation.The Ce anomalies suggested that the carbonates precipitated in an anoxic environment.A slight enrichment of middle REEs(MREEs)could be attributable to the early diagenesis.The structures,minerals,oxygen isotopes,and MREEs all indicated that the carbonates experienced some degree of early diagenesis.Therefore,the infl uence of early diagenesis should be considered when using geological and geochemical proxies to reconstruct original methane seepage environments.

关键词： authigenic carbonate carbon and oxygen isotopes rare earth elements(REEs) anaerobic oxidation of methane(AOM) northern Okinawa Trough

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Effect of Temperature on the Release of Transparent Exopolymer Particles(TEP)and Aggregation by Marine Diatoms(Thalassiosira weissflogii and Skeletonema marinoi)

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Journal of Ocean University of China 2021年第1期20卷 56-66页

作者： CHEN Jie GUO Kangli Daniel COThornton WU Yi Fourth Institute of Oceanography Ministry of Natural ResourcesBeihai 536007China Department of oceanography Texas A&M UniversityCollege StationTexas 77843USA

The presence of diatoms is accompanied by the production of a large amount of extracellular polymeric substances,which are mainly composed of carbohydrates.Transparent exopolymer particles(TEP)are a large class of extracellular polymeric substances with high stickiness that promotes the formation of aggregates and marine snow,which affects marine bio-carbon pump efficiency.The purpose of this research was to determine how temperature increases affect the allocation of cellular carbohydrates and the formation and aggregation of TEP.The results showed that the responses of two different diatom species(Thalassiosira weissflogii and Skeletonema marinoi)differed according to temperature.The cell density and chlorophyll a concentration of the former were not significantly correlated with temperature,while those of the latter were significantly decreased with increasing temperature.This indicates that the two species of diatom may have different heat tolerance ranges.A temperature increase will promote significant formation of TEP by both types of diatoms,including aggregation of S.marinoi as the temperature rises,meaning that the high temperature will produce an aggregate with a larger particle size and thus may increase the sedimentation rate of organic carbon.Moreover,the TEP aggregation of T.weissflogii did not increase;therefore,its particle size was smaller,and so it may remain on the sea surface at high temperatures for longer periods.These influences have a profound impact on the biogeochemical cycling of carbon.

关键词： transparent exopolymer particles diatom Thalassiosira weissflogii Skeletonema marinoi aggregation

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Embryonic and larval development of garpike from the Adriatic Sea

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Integrative Zoology 2009年第3期4卷 272-276页

作者： Jakov DULCIC Branimir BAZDARIC Leon GRUBISIC Pero TUTMAN Branko DRAGICEVIC Institute of Oceanography and Fisheries SplitCroatia

Although information about embryonic and larval development of garpike,Belone belone(Linnaeus,1761),is present in the published literature,the bulk of research concerns garpike from the northeastern Atlantic Ocean and the Baltic Sea.The present work describes the embryonic and larval development of garpike,Belone belone,from the Adriatic Sea,and methods used for incubation of fertilized eggs in aquarium conditions.Because garpike is,as suggested by some authors,divided into subspecies,we conclude that some differences in embryonic development could also be expected.In the present study,eggs were fertilized using the dry fertilization method and were incubated in a tank equipped with aeration and constant sea water flow.Salinity and content of dissolved oxygen were constant,and the temperature varied between 19.4 and 22.3°C.Eggs were spherical,measuring 3071.9±75.73μm in diameter.Yolk sacs were homogeneous and did not contain oil globules.The first larvae hatched 329 h and 47 min after fertilization.Absorption of the yolk sac occurred 17 h–48 h after hatching and the total length of newly hatched larvae was 9.78 mm.The peculiarities observed in the embryonic and early larval development are evidence of an exceptional plasticity and adaptive potential,which could be considered as helpful features in extending the natural range of occurrence of this species.

关键词： Adriatic Sea Belone belone embryonic development larval development.

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Mantle melting beneath the Southwest Indian Ridge: signals from clinopyroxene in abyssal peridotites

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Acta Oceanologica Sinica 2013年第12期32卷 50-59页

作者： WANG Wei CHU Fengyou ZHU Jihao DONG Yanhui YU Xing CHEN Ling LI Zhenggang The Second Institute of Oceanography State Oceanic Administration

The mineral chemistry and texture of clinopyroxenes in peridotite from the Kingkong tectonic zone of the Southwest Indian Ridge segment in an effort to constrain mantle melting beneath this slow-spreading ridge are reported. There are three types of clinopyroxenes in the abyssal peridotites： coarse-grained, intergranu- lar and exsolved. The compositional variations among these three types suggest that the coarse-grained clinopyroxene is a mantle-derived source. The A1, Na and Ti contents and the Na/Ti ratio of the coarse- grained clinopyroxene may be used to monitor the degree of partial melting, combined with the contradis- tinction with Spinel Cr#, which is calculated to be between 7.9% and 14.9%, and may represent low degrees of melting in the global ocean ridge system. The along-axis compositional variations in the coarse-grained clinopyroxene suggest that the degree of partial melting is primarily controlled by the transform faults on both sides of the ridge. Nonetheless, the northwestern side of the ridge may be affected by a hypothesised detachment fault as documented by the calculated P-T conditions. Simultaneously high Na and low Ti con- tents in the coarse-grained clinoovroxene points to mantle heterogeneities along the ridge axis.

关键词： partial melting abyssal peridotite clinopyroxene major elements SWIR

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