2018 Vol. 37, No. 11

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Quantifying cold front induced water transport of a bay with in situ observations using manned and unmanned boats
WEEKS Eddie, ROBINSON Mark E, LI Chunyan
2018, 37(11): 1-7. doi: 10.1007/s13131-018-1330-1
The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler (ADCP) mounted on an Automated Surface Craft (ASC), known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously (with only one major gap), with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.
The spatiotemporal features of submesoscale processes in the northeastern South China Sea
DONG Jihai, ZHONG Yisen
2018, 37(11): 8-18. doi: 10.1007/s13131-018-1277-2
The spatiotemporal features of submesoscale processes (SMPs) in the northeastern South China Sea (SCS) are analyzed based on a high-resolution simulation from 2009 to 2012. The simulation results show that the SMPs with a vertical relative vorticity that matches the local planetary vorticity are ubiquitous in the upper ocean of the northeastern SCS. The SMPs distribution shows an asymmetry due to centrifugal instability, with stronger positive vorticity than negative vorticity. Meanwhile, the SMPs demonstrate an obvious seasonal variation. The SMPs are strong and active in winter but weak and inactive in summer. An investigation of the SMPs generation mechanisms reveals that flow straining and mixed layer depth account for this seasonal variation. The strong flow straining and deep mixed layer depth in winter favor the SMP generation via frontogenesis and mixed layer instability.
Characteristics analysis for cold water patches off the Jiangsu coast in the last 35 a
ZHU Shouxian, HE Zhanyuan, ZHANG Wenjing, XIE Shijian, XU Yucheng
2018, 37(11): 19-25. doi: 10.1007/s13131-018-1293-2
The daily and monthly-mean characteristics of cold water patches (CWPs) off the Jiangsu coast in 35 a of 1982-2016 are examined based on advanced very high resolution radiometer (AVHRR) data. Most of the CWPs are found to occur in the warm and hot months (May-September), with some CWPs in the cool and cold months (October-April). The average radius and intensity of the monthly-mean CWPs are about 81 km and 0.6℃, respectively. The average difference in the sea surface temperature (SST) between the centers of the CWPs and the nearshore is about 2.0℃. The correlation analysis between the CWPs, winds and tides indicates that most of the CWPs occurred during the southerly winds, with some CWPs occurring during the northerly winds. The average intensity of the CWPs during spring tides is slightly stronger than that during neap tides in the warm and hot months, and the difference is very small in the cool and cold months.
Estimation and prediction of plastic waste annual input into the sea from China
BAI Mengyu, ZHU Lixin, AN Lihui, PENG Guyu, LI Daoji
2018, 37(11): 26-39. doi: 10.1007/s13131-018-1279-0
Marine plastic debris has been a pervasive issue since the last century, and research on its sources and fates plays a vital role in the establishment of mitigation measures. However, data on the quantity of plastic waste that enters the sea on a certain timescale remain largely unavailable in China. Here, we established a model using material flow analysis method based on life cycle assessment to follow plastic product from primary plastic to plastic waste with statistical data and monitoring data from accurate sources. This model can be used to estimate and forecast the annual input of plastic waste into the sea from China until 2020. In 2011, 0.547 3-0.751 5 million tons of plastic waste entered the seas in China, with a growth rate of 4.55% per year until 2017. And the amount will decrease to 0.257 1 to 0.353 1 million tons in 2020 under the influence of governmental management. The amount of plastic waste discharged from coastal areas calculated in this study was much larger than that from river, thus it is suggested to strengthen the governance and control of plastic waste in coastal fishery activities in China in order to reduce the amount of marine plastic waste input.
The sedimentary facies and dynamic environment of the Diaokou lobe in the modern Huanghe River Delta of China
GAO Wei, LIU Shihao, LIU Jie, XU Yuanqin, LI Ping
2018, 37(11): 40-52. doi: 10.1007/s13131-018-1332-z
The Huanghe River captures the Diaokou River in 1964 and forms a deltaic lobe in the subsequent 12 a. The progradational process of the Diaokou lobe is in associated with complicated evolution of riverine sheet flooding, merging, and swinging. On the basis of 11 borehole cores and 210 km high resolution seismic reflection data set, the sedimentary sequence and dynamic environment of the Diaokou lobe (one subdelta lobe of the modern Huanghe River Delta) are studied. The stratigraphy of the lobe is characterized by an upward-coarsening ternary structure and forms a progradational deltaic clinoform. Totally six seismic surfaces are identifiable in seismic profiles, bounded six seismic units (SUs). These SUs correspond to six depositional units (DUs) in the borehole cores, and among them, SUs 4-6 (DUs D to F) consist of the modern Diaokou lobe. Lithological and seismic evidences indicate that the delta plain part of the Diaokou lobe is comprised primarily by fluvial lag sediments together with sediments from sidebanks, overbanks, fluvial flood plains and levees, while the delta front part is a combination of river mouth bar sands (majority) and distal bar and deltaic margin sediments (minority). As a result of the high sedimentation rate and weak hydrodynamic regime in the Huanghe River Delta, the sediments in the delta front are dominated by fine-grained materials. The grain size analysis indicates the Huanghe River hyperpycnal-concentrated flow shows the suspension, transportation and sedimentation characteristics of gravity flow, and the sediment transportation is primarily dominated by graded suspension, while uniform suspension and hydrostatic suspension are also observed in places. The strength of the hydrodynamic regime weakens gradually offshore from riverbed, river mouth bar, sidebank, distal bar subfacies to delta lateral margin and flooding plain subfacies.
Modeling of normal faulting in the subducting plates of the Tonga, Japan, Izu-Bonin and Mariana Trenches: implications for near-trench plate weakening
ZHOU Zhiyuan, LIN Jian, ZHANG Fan
2018, 37(11): 53-60. doi: 10.1007/s13131-018-1146-z
The plate flexure and normal faulting characteristics along the Tonga, Japan, Izu-Bonin and Mariana Trenches are investigated by combining observations and modeling of elastoplastic deformation of the subducting plate. The observed average trench relief is found to be the smallest at the Japan Trench (3 km) and the largest at the Mariana Trench (4.9 km), and the average fault throw is the smallest at the Japan Trench (113 m) and the largest at the Tonga Trench (284 m). A subducting plate is modeled to bend and generate normal faults subjected to three types of tectonic loading at the trench axis: vertical loading, bending moment, and horizontal tensional force. It is inverted for the solutions of tectonic loading that best fit the observed plate flexure and normal faulting characteristics of the four trenches. The results reveal that a horizontal tensional force (HTF) for the Japan Trench is 33%, 50% and 60% smaller than those of the Mariana, Tonga and Izu-Bonin Trenches, respectively. The normal faults are modeled to penetrate to a maximum depth of 29, 23, 32 and 32 km below the sea floor for the Tonga, Japan, Izu-Bonin and Mariana Trenches, respectively, which is consistent with the depths of relocated normal faulting earthquakes in the Japan and Izu-Bonin Trenches. Moreover, it is argued that the calculated horizontal tensional force is generally positively correlated with the observed mean fault throw, while the integrated area of the reduction in the effective elastic thickness is correlated with the trench relief. These results imply that the HTF plays a key role in controlling the normal faulting pattern and that plate weakening can lead to significant increase in the trench relief.
Newly discovered hydrothermal fields along the ultraslow-spreading Southwest Indian Ridge around 63°E
CHEN Jie, TAO Chunhui, LIANG Jin, LIAO Shili, DONG Chuanwan, LI Huaiming, LI Wei, WANG Yuan, YUE Xihe, HE Yonghua
2018, 37(11): 61-67. doi: 10.1007/s13131-018-1333-y
The ultraslow-spreading Southwest Indian Ridge (SWIR) to the east of the Melville fracture zone is characterized by very low melt supply and intensive tectonic activity. Due to its weak thermal budget and extremely slow spreading rate, the easternmost SWIR was considered to be devoid of hydrothermal activity until the discovery of the inactive Mt. Jourdanne hydrothermal field (27°51'S, 63°56'E) in 1998. During the COMRA DY115-20 cruise in 2009, two additional hydrothermal fields (i.e., the Tiancheng (27°51'S, 63°55'E) and Tianzuo (27°57'S, 63°32'E) fields) were discovered. Further detailed investigations of these two hydrothermal sites were conducted by Chinese manned submersible Jiaolong in 2014-2015. The Tiancheng filed can be characterized as a low-temperature (up to 13.2℃) diffuse flow hydrothermal field, and is hosted by fractured basalts with hydrothermal fauna widespread on the seafloor. The Tianzuo hydrothermal field is an inactive sulfide field, which is hosted by ultramafic rocks and controlled by detachment fault. The discovery of the three hydrothermal fields around Segment #11 which receives more melt than the regional average, provided evidence for local enhanced magmatism providing heat source to drive hydrothermal circulation. We further imply that hydrothermal activity and sulfide deposits may be rather promising along the easternmost SWIR.
The influence of up-wave barge motion on the water resonance at a narrow gap between two rectangular barges underwaves in the sea
JIN Ruijia, NING Dezhi, BAI Wei, GENG Baolei
2018, 37(11): 68-76. doi: 10.1007/s13131-018-1334-x
A three-dimensional time-domain potential flow model is developed and applied to simulate the wave resonance in a gap between two side-by-side rectangular barges. A fourth-order predict-correct method is implemented to update free surface boundary conditions. The response of an up-wave barge is predicted by solving the motion equation with the Newmark-β method. Following the validation of the developed numerical model for wave radiation and diffraction around two side-by-side barges, the influence of up-wave barge motion on the gap surfaceresonance is investigated in two different locations of the up-wave barge relative to the back-wave barge at various frequencies. The results reveal that the freely floating up-wave barge significantly influences the resonance frequency and the resonance wave amplitude. Simultaneously, the up-wave barge located in the middle of the back-wave barge leads to a reduction in the resonance wave amplitude and motion response when compared with other configurations.
Analysis of impacting factors on polarimetric SAR oil spill detection
SONG Shasha, ZHAO Chaofang, AN Wei, LI Xiaofeng, WANG Chen
2018, 37(11): 77-87. doi: 10.1007/s13131-018-1335-9
Polarimetric synthetic aperture radar (SAR) oil spill detection parameters conformity coefficient (μ), Muller matrix parameters (|C|, B0), the eigenvalues of simplified coherency matrix (λnos) and the influence of SAR observing parameters, ocean environment and noise level are investigated. Radarsat-2 data are used to make systematic analysis of polarimetric parameters for different incidences, wind speeds, noise levels and the ocean phenomena (oil slick and look likes). The influence of the SAR observing parameters, the ocean environment and the noise level on the typical polarimetric SAR parameter conformity coefficient has been analyzed. The results indicate that conformity coefficient cannot be simply used for oil spill detection, which represents the image signal to the noise level to some extent. When the signals are below the noise level for the oil slick and the look likes, the conformity coefficients are negative; while the signals above the noise level corresponds to positive conformity coefficients. For dark patches (low wind and biogenic slick) with the signal below the noise, polarization features such as conformity coefficient cannot separate them with oil slick. For the signal above the noise, the oil slick, the look likes (low wind and biogenic slick) and clean sea all have positive conformity coefficients, among which, the oil slick has the smallest conformity coefficient, the look likes the second, and the clean sea the largest value. For polarimetric SAR data oil spill detection, the noise plays a significant role. So the polarimetric SAR data oil spill detection should be carried out on the basis of noise consideration.
An experimental study on oil droplet size distribution in subsurface oil releases
LI Jianwei, AN Wei, GAO Huiwang, ZHAO Yupeng, SUN Yonggen
2018, 37(11): 88-95. doi: 10.1007/s13131-018-1258-5
Oil droplet size distribution (ODSD) plays a critical role in the rising velocity and transport of oil droplets in subsurface oil releases. In this paper, subsurface oil release experiments were conducted to study ODSD under different experimental conditions in a laboratory water tank observed by two high-speed cameras in March and April 2017. The correlation formulas Oh=10.2Re-1 and Oh=39.2Re-1 (Re represents Reynolds number and Oh represents Ohnesorge number) were established to distinguish the boundaries of the three instability regimes in dimensionless space based on the experimental results. The oil droplet sizes from the experimental data showed an excellent match to the Rosin-Rammler distribution function with determination coefficients ranging from 0.86 to 1.00 for Lvda 10-1 oil. This paper also explored the influence factors on and change rules of oil droplet size. The volume median diameter d50 decreased steadily with increasing jet velocity, and a sharp decrease occurred in the laminar-breakup regime. At Weber numbers (We) < 100, the orifice diameter and oil viscosity appeared to have a large influence on the mean droplet diameter. At 100 < We < 1 000, the oil viscosity appeared to have a larger influence on the relative mean droplet diameter.
Laboratory investigation into the oil diffusion from submarine pipeline under water flow
JIANG Meirong, YU Jianxing, LI Zhigang, ZHONG Wenjun, WU Zhaohui, YU Yang
2018, 37(11): 96-103. doi: 10.1007/s13131-018-1257-6
A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow. The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The oil trajectory, velocity and the rising time to the surface are obtained through this system. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled discharge is the primary factor affecting the rising time of the oil particles. In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity. The study can provide a theoretical reference for the prediction system of oil spill emergency.
Application of computational fluid dynamics simulation for submarine oil spill
YANG Zhenglong, YU Jianxing, LI Zhigan, CHEN Haicheng, JIANG Meirong, CHEN Xi
2018, 37(11): 104-115. doi: 10.1007/s13131-018-1256-7
Computational fluid dynamics (CFD) codes are being increasingly used in the simulation of submarine oil spills. This study focuses on the process of oil spills, from damaged submarine pipes, to the sea surface, using numerical models. The underwater oil spill model is developed, and a description of the governing equations is proposed, along with modifications required for the particalization of the control volume. Available experimental data were introduced to evaluate the validity of the CFD predictions, the results of which proved to be in good agreement with the experimental data. The effects of oil leak rate, leak diameter, current velocity, and oil density are investigated, by the validated CFD model, to estimate the undersea leakage time, the lateral migration distance, and surface diffusion range when the oil reaches the sea surface. Results indicate that the leakage time and lateral migration distance increase with decreasing leak rates and leak diameter, and increase with increasing current velocity and oil density. On the other hand, a large leak diameter, high density, high leak rate, or fast currents result in a greater surface diffusion range. The findings and analysis presented here will provide practical predictions of oil spills, and guidance for emergency rescues.
Establishment and application of an intelligent treating method for oil spill identification
TAN Liju, ZHAO Ruxiang, YIN Xiaonan, ZHANG Haijiang, WANG Jiangtao
2018, 37(11): 116-122. doi: 10.1007/s13131-018-1254-9
In the identifying process of an oil spill accident, manual integral and artificial visual comparison are commonly used at present to determine the oil spill sources, these methods are time-consuming and easily affected by human factors. Therefore, it is difficult to achieve the purpose of rapid identification of an oil spill accident. In this paper, an intelligent method of automatic recognition, integration and calculation of diagnostic ratio of Gas Chromatography-Mass Spectrometer (GC/MS) spectrum are established. Firstly, four hundreds of samples collected around the world were analyzed using a standard method and Retention time locking technology (RTL) was applied to reduce the change of retention time of GC/MS spectrum. Secondly, the automatic identification, integration of n-alkanes, biomarker compounds, polycyclic aromatic hydrocarbons and calculation of the diagnostic ratios were realized by MATLAB software. Finally, a database of oil fingerprints were established and applied successfully in a spill oil accident. Based on the new method and database, we could acquire the diagnostic ratios of an oil sample and find out the suspected oil within a few minutes. This method and database can improve the efficiency in spilled oil identification.
Comparison of toxicity effects of fuel oil treated by different dispersants on marine medaka (Oryzias melastigma) embryo
GAO Xiang, DING Guanghui, LI Xishan, XIONG Deqi
2018, 37(11): 123-132. doi: 10.1007/s13131-018-1255-8
This study aims to evaluate the subacute toxic effects of oil under different treatments on marine organism by simulating natural contaminative processes. In this study, 120# (RMD15) fuel oil was selected as the pollutant and marine medaka (Oryzias melastigma) embryos as the experimental organism. The developmental toxicity of different volume concentrations (0.05%, 0.2%, 1% and 5%) of water-accommodated fractions, biologically-enhanced water-accommodated fractions, and chemically-enhanced water-accommodated fractions on the embryos in different exposure time (8, 15 and 22 d) were compared and the content of relevant polycyclic aromatic hydrocarbons (PAHs) was studied (in dispersion and in vivo). The subacute toxic effects were assessed in terms of antioxidant activities of enzymes (superoxide dismutase, catalase and glutathione S-transferase) and the blue sac disease (BSD) indexes.The results showed that the BSD indexes of the treatment groups were significantly higher than the respective control groups and showed positive correlations with both concentration and exposure time. The experiments with three antioxidant enzymes indicated that enzymatic activities of the embryos changed dramatically under the oxidation stress of petroleum hydrocarbons, especially after adding the dispersants. With the increase of petroleum hydrocarbon concentration and exposure time, the three enzymes showed different degrees of induction and inhibition effects.
Research on the risk-based model for regional emergency resource allocation for ship-source oil spill
ZHANG Chunchang, AN Wei, XIONG Deqi, LIU Baozhan, SONG Shasha
2018, 37(11): 133-138. doi: 10.1007/s13131-018-1253-x
The key point for rational allocation of emergency resources is to match the oil spill response capacity with the risk of oil spill. This paper proposes an innovative risk-based model for quantitative regional emergency resource allocation, which comprehensively analyzes the factors such as oil spill probability, hazard consequences, oil properties, weathering process and operation efficiency, etc. The model calculates three major resources, i.e., mechanical recovery, dispersion and absorption, according to the results of risk assessment. In a field application in Xiaohu Port, Guangzhou, China, and the model achieved scientific and rational allocation of emergency resources by matching the assessed risk with the regional capacity, and allocating emergency resources according to capability target. The model is considered to be beneficial to enhancing the resource efficiency and may contribute to the planning of capacity-building programs in high-risk areas.