Open Sea Areas Research Articles

Numerical Simulation of Bohai Oil Spill in the Winter Sea Ice Period

The Bohai Sea is a seasonal icy sea area that has the lowest latitude of any sea experiencing icing in the northern hemisphere, and simulation studies on oil spills during its sea ice period are the key to analyzing winter oil spill accidents. This study applied the three-dimensional free surface to establish a high-resolution hydrodynamic model and simulate tidal distributions in the Bohai Sea. Then, the oil spill model of the open sea area and thermodynamic model were combined to establish a numerical model for the Bohai oil spill during the winter sea ice period. The hydrodynamic model and sea ice growth and melting model were verified, and the parameters were adjusted based on the measured values, which indicate that the numerical model established in this paper is of high accuracy, stability and ubiquity. Finally, after checking the calculations repeatedly, the diffusion coefficient for the Bohai Sea was determined to be 1.0×10–7 m2/s. It is better that the comprehensive weathering attenuation coefficient is lower than that of a non-winter oil spill, with 1.3×10–7 m2/s being the most appropriate coefficient. This study can provide the reliable technical support for the operational safety and reduction in losses caused by winter oil spill accidents for the petroleum industry.

Gaseous elemental mercury (Hg(0)) in the surface air over the Sea of Japan, the Sea of Okhotsk and the Kuril-Kamchatka sector of the Pacific Ocean in August–September 2017

The northwestern Pacific Ocean including the Sea of Japan and the Sea of Okhotsk is one of the least studied regions in terms of mercury behavior and distribution in the sea-atmosphere system. In August and September 2017, we determined gaseous elemental mercury (Hg(0)) in the surface air over this water areas along a 12,000 km cruise. Concentrations varied from 1.07 to 2.74 ng m−3, with an average value of 1,68 ± 0.23 ng m−3 (N = 1853). The average concentrations for the Sea of Japan, the Sea of Okhotsk and the Kuril-Kamchatka sector of the Pacific Ocean were 1.61 ng m−3, 1.71 ng m−3 and 1.61 ng m−3, respectively. The maximum concentrations were observed in the Sea of Okhotsk during periods when air masses arrived from the southern and central Kuril Islands. We believe that the reason for that was volcanic activity. The minimum concentrations were registered in air masses arriving from the northeastern Russia and from open sea areas. In the Sea of Okhotsk we measured Hg(0) concentrations near the cyclone eye and did not register any increase due to increased turbulence. This fact contradicts the previously expressed hypothesis that a strong turbulence above the sea surface causes enhanced Hg(0) concentrations in the air. Apparently there are additional or completely different influencing factors which could provide such increase. Also we found that the diurnal Hg(0) cycle in the Sea of Japan was the opposite of the diurnal Hg(0) cycle in the Sea of Okhotsk.

Spatial Effects of Different Zebra Mussel Farming Strategies in an Eutrophic Baltic Lagoon

Finding suitable places to establish a mussel farm is challenging, as many aspects like mussel growth, clearance effect and the risk of low oxygen conditions, have to be considered. We present a tailor-made approach, combining field experiments with a spatially explicit model tool, to support the planning process. A case study was set up in the German part of Szczecin (Oder) Lagoon (Baltic Sea), as it shows all typical eutrophication problems and has a strong need and high potential for nutrient retention measures. Farming zebra mussels (Dreissena polymorpha) is an innovative approach that utilizes a species which is often perceived as a pest. The practical applicability and water quality improvement potential was proven by a pilot farm. Combining the gained knowledge with the simulation model led to a cascade of mussel farm options that differ in purpose, location and biomass. Placing a mussel farm in an enclosed bay resulted in a remarkable water quality improvement (Secchi Depth increased up to 2 m), but the effect stayed local, the growth was limited and the potential annual nutrient removal reached a threshold of approximately 30 t N and 2.8 t P. The same nutrient removal could be reached with much smaller farms in an open sea area, whereas the change of water transparency or bottom oxygen conditions were neglectable. A maximal nutrient removal potential of 1,750 t N and 160 t P per year was estimated, when nearly the entire German part of Szczecin Lagoon with mussel farms was used. This led to a strong reduction of phytoplankton and an increase of Secchi Depth, but also a rising risk of anoxia. Overall, all mussel farm options are only a supportive measure, but not sufficient to reach the Good Environmental Status demanded by the Water Framework Directive. At once, the nutrient export from Szczecin Lagoon to the open Baltic was reduced by up to 3,500 t N and 420 t P per year, making the large-scale mussel farm option also a potential measure within the Marine Strategy Framework Directive.

Seasonal Dynamics of Microbial Processes in Bottom Sediments of the Sevastopol Coastal Area

A seasonal study of microbial methane oxidation (MO) and sulfate reduction (SR) processes in bottom sediments was carried out at five stations in the estuarian Sevastopol coastal area, which differed in their sedimentation and geochemical conditions. High methane concentrations in bottom sediments, as well as accordingly high MO rates, were obtained at stations marked by high organic carbon (Corg) concentrations. The dependence of these values was found to be exponential, whereas for SR, the amount of organic carbon was not the limiting factor. For the studied stations, the integral SR rates ranged from 2.9 to 11.3 mmol m–2 day–1. The trends of the SR rate have opposite directions for the open and closed parts of the sea: SR decreased during study period at the center of the bay, while in the open sea area it increased. The MO rates varied in a wide range from 0.0001 to 3.6 mmol m–2 day–1; the highest were obtained in Corg-rich sediments of the central part of the bay. Only at one station, where the mean annual Corg content in sediments reached 3.39%, did the methane concentration in sediment pore water exceed the calculated solubility.

Marine geological researches in the greater bay of Navarino area, Southern Ionian sea

This paper examines the marine area of the Bay of Navarino and the Ionian sea sector to the west of the bay, based on a collection of shallow and intermediate penetration seismic profiles and on three gravity cores. The Bay has a smooth sea bottom morphology with maximum depth (75m) toward the south. Two minor reefs penetrate the sea bottom, one of them rising above the sea level forming a rocky island. In the open sea area the sea bottom is anomalous, especially after the shelf break, that is distinguished at a depth of approx. 160m. Beyond this depth deep valleys and ridges alternate and produce a rough morphology. The examination of the three gravity cores indicated that their sediment sand composition is mainly biogenic with minor amounts of terrigenous material. Increased shell fragments and terrigenous material was found at the bottom of one core taken at a depth of 116m, related probably to wave action at an earlier sea level position. The study of the seismic profiles collected within the bay and in the shelf area revealed,the presence of two distinct sedimentation units, un upper A filling with loose sediments the basins that are formed in the lower Y which is the basement. Within unit A two distinct subunits are recognized Al and A2, separated by an unconformity. In the sector to the west of the bay and beyond the shelf break, alternating opaque and transparent sediment packages are present, that are attributed to earlier sedimentation phases of low/high sea level stages. An older shelf break feature correlated with sea level stage 6 was distinguished at approx. 250m. sea depth. Thus subsidence rate in the area is estimated between 1 and 2 mm/year. The comparison of all data with the known sea level change curve indicated that unit AI was deposited during and after the latest transgression (stage 1) the unconformity between Al and A2 is related to the previous regression (stage 2), while the deposition of the unit A2 took place probably during stages 3 and/or 5. The morphology of the basement Y in the bay and the shelf area is thus attributed probably to stage 6 when the area was again subaerially exposed.

Concentrations, Distribution, and Ecological Risk Assessment of Heavy Metals in Daya Bay, China

Surface sediment samples were collected from 19 sites throughout Daya Bay, China to study the concentrations, spatial distributions, potential ecological risk, and possible sources of heavy, including metals copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), nickel (Ni), lead (Pb), mercury (Hg), and chromium (Cr). The mean concentrations of the eight heavy metals were 24, 109, 6.5, 0.09, 35.3, 26.8, 0.07, and 109 µg g−1, respectively. The concentrations of most heavy metals were within range of those recorded in previous years. The spatial distribution pattern of most heavy metals were similar, with lowest values recorded along the southeast coast and the open sea area; the highest values were recorded in the northern Daya Bay, especially the northwest. Cu, Zn, As, Cd, Pb, and Hg were classified as Class I, and Ni and Cr were classified as Class II according to the Sediment Quality Guidelines (SQGs) of China. The potential ecological risk (Eif) indices of Cu, Zn, As, Pb, Ni, and Cr specify that these metals pose low risk to the ecosystem of the Bay, whereas Cd and Hg pose a very high risk in some sites. The geoaccumulation indices (Igeo) of Cu, Zn, As, Ni, and Cr specify weak or no pollution in Daya Bay, whereas those of Pb, Cd, and Hg in some sites indicate moderate or even high pollution. Spatial distribution, carbon/nitrogen analysis, Pearson correlation, and principal components analysis indicated that Cu, Zn, As, Pb, Ni, Cr, total organic carbon (TOC), and total nitrogen (TN) originated from the same sources. Ballast water or sewage from the cargo ships that park at the harbors or anchor in the Bay were the important sources for Cu, Zn, As, Pb, Ni, Cr, TOC, and TN. Other anthropogenic sources, such as agricultural runoff and aquaculture, might also be responsible, whereas Hg and Cd originated from other point sources.

Spatiotemporal variations in macrofaunal assemblages linked to site-specific environmental factors in two contrasting nearshore habitats

A long-term study on a benthic community was conducted in two different localities, one in semi-enclosed bay of Jinhae (n = 10, south coast) and the other in open sea area of Samcheok (n = 10, east coast), Korea, respectively. We aimed to identify the spatiotemporal patterns of macrozoobenthos and the environmental variables influencing such patterns in the two contrasting habitats. The macrozoobenthos assemblages on the soft bottom of the subtidal zone were analyzed over the 3 years, encompassing 12 consecutive seasons, in 2013–2016. Among the 22 environmental variables measured, organic matter, dissolved oxygen, mean grain size, and water depth showed clear differences between two study areas. Accordingly, several ecological indices (such as the number of species, abundance, dominant species, and diversity index (H’)) generally reflected site-specific benthic conditions. The macrofaunal community in the Jinhae showed typical seasonal fluctuations, whereas the Samcheok community showed no significant change over time and space. Region- or site-dependent temporal variabilities of macrofaunal assemblages are depicted through cluster analysis (CA), indicating distinct temporal changes in the composition of dominant species. In particular, the abundance of some dominant species noticeably declined in certain seasons when several opportunistic species peaked. Such faunal succession might be explained by significant changes to specific environmental factors, such as bottom dissolved oxygen, grain size, and water depth. Principle component analysis further identified major environmental factors, i.e., sediment properties in Jinhae and water quality parameters in Samcheok community, respectively. In addition, discriminant analysis confirmed the presence of several site-specific parameters for the faunal assemblage groups identified through CA. Finally, indicator value analysis identified species that were representative across stations and regions in accordance with their habitat preference and/or species tolerance. Overall, the two contrasting nearshore habitats showed distinct community differences, in time and space, that were influenced by site-dependent environmental conditions.

The North Sea goes viral: Occurrence and distribution of North Sea bacteriophages

Marine viruses are dominated by phages and have an enormous influence on microbial population dynamics, due to lysis and horizontal gene transfer. The aim of this study is to analyze the occurrence and diversity of phages in the North Sea, considering the virus-host interactions and biogeographic factors. The virus community of four sampling stations were described using virus metagenomics (viromes). The results show that the virus community was not evenly distributed throughout the North Sea. The dominant phage members were identified as unclassified phage group, followed by Caudovirales order. Myoviridae was the dominant phage family in the North Sea, which occurrence decreased from the coast to the open sea. In contrast, the occurrence of Podoviridae increased and the occurrence of Siphoviridae was low throughout the North Sea. The occurrence of other groups such as Phycodnaviridae decreased from the coast to the open sea. The coastal virus community was genetically more diverse than the open sea community. The influence of riverine inflow and currents, for instance the English Channel flow affects the genetic virus diversity with the community carrying genes from a variety of metabolic pathways and other functions. The present study offers the first insights in the virus community in the North Sea using viromes and shows the variation in virus diversity and the genetic information moved from coastal to open sea areas.

Distribution of fragrances and PAHs in the surface seawater of the Sicily Channel, Central Mediterranean

The Mediterranean Sea is highly influenced by several anthropic pressures, including different kinds of organic pollutants. Fragrance Materials (FMs) and Polycyclic Aromatic Hydrocarbons (PAHs) were investigated in the surface seawater of the Sicily Channel in offshore and coastal areas. Total concentrations of FMs and PAHs resulted respectively up to 112ngL−1 and 43ngL−1, with similar distributions of both classes of analytes. Low values were detected in some coastal samples, due to the upwelling of deep and unpolluted waters, while the presence of gyres probably accumulates contaminants in offshore areas. Confirming previous works, the allergenic and oestrogenic Salicylates generally resulted the most abundant FMs and diagnostic ratios indicated combustion processes as the sources of PAHs. The coupling of the well-known PAHs with a new class of Personal Care Products (PCPs) helped the identification of the major environmental drivers: the results highlighted the role of mesoscale hydrodynamics and suggested long-range atmospheric transport as key factors. The first detection of the selected FMs in open sea areas supports the hypothesis of their environmental persistence.

Development of SRIAM Computation Module for Enhanced Calculation of Nonlinear Energy Transfer in 3rd Generation Wave Models

Because of the rapid development of computer technology in recent years, wave models can utilize parallel calculations for the high-resolution prediction of open sea and coastal areas with high accuracy. Parallel calculations also allow national agencies in the relevant sectors to produce marine forecasting data through massive parallel calculations. Meanwhile, the eastern coast of the Korean Peninsula has been increasingly damaged by swell-like high waves, and many researchers and scientists are continuing their efforts to anticipate and reduce the damage. In general, the short-term transformation of swell-like high waves can be reproduced relatively well in the third generation wave models, but the transformation of relatively long period waves needs to be simulated with higher accuracy in terms of the nonlinear wave interactions to gain a better understanding of the low-frequency wave generation and development mechanisms. In this study, we developed a calculation module to improve the calculation of the nonlinear energy transfer in the 3rd generation wave model and integrated it into the wave model to effectively consider the nonlinear wave interaction. First, the nonlinear energy transfer calculation module and third generation model were combined. Then, the combined model was used to reproduce the wave transformation due to the nonlinear interaction, and the performance of the developed operation module was verified.

Solar Energy Hybrid System for Seawater Distillation in the Coastal Regions

Coastal regions and small islands in the open sea areas are commonly poor in fresh-water resource availability. Because of its high-level of hardness, the seawater is in general not much used for everyday life. In tropical countries like Indonesia, the daily duration of solar irradiation throughout the year does not vary much, with an average of about 12 hours a day. The solar energy can be used to evaporate seawater and to produce fresh-water coming from the steam condensation through a distillation process. It is shown in this research that using a hybrid system the fresh-water production can be extended to the period when the solar radiation is insufficient, so that the solar energy usage can be maximized. It can be used for heating the seawater directly in an evaporating house while being used at the same time to produce electricity using solar cells. As the voltage generated by the solar cells was not of constant value depending on the incident irradiation, a cuk converter being operated based on the Pulse-Width Modulation (PWM) principle has been used to stabilize the voltage fed into a battery at 15V-level. It was furthermore used to supply the heating system after being inverted into an AC voltage waveform. It would be functioning when the solar irradiation was not sufficient to evaporate the seawater directly. The internal temperature of the evaporating room was known using a sensor PT100. The sensor data needed to be conditioned before being processed furthermore in a microcontroller Arduino Uno. After reaching the desired temperature setting point, a relay circuit module would operate to cut off the current and to turn on/off the heating system. The generated steam has been passed through a condenser to produce the fresh-water. The results of the study showed that an amount of 3.5 litres of seawater being evaporated during 10 hours would produce 1.076 litres of fresh-water using a total power of 184.06W.

Identifying Distribution of Chlorophyll-a Concentration Using Landsat 8 OLI on Marine Waters Area of Cirebon

Phytoplankton is a microscopic plant that has a function to produces oxygen and organic substances. It also plays a role as a main producer in the food chain of a marine ecosystem. Chlorophyll-a is a colour pigment most common in phytoplankton species, so that the concentration level of chlorophyll-a can be used as an indicator of the abundance of phytoplankton cells, and as a reference for predicting organic potency in the aquatic area. This research discusses about the spatial and temporal distribution of chlorophyll-a and its correlation with salinity and total suspended solid (TSS), in the seawaters of Cirebon, West Java. The goal of this research is to be a source of information for fishermen, and other stakeholders whose related subjects in the field of marine and fisheries to predict fertile water regions and can also be used as an indicator in discovering potential areas to catch pelagic fish in Cirebon seawaters. Chlorophyll-a concentration, salinity, and TSS are identified using remote sensing data such as Landsat-8 OLI multi temporal images according to dry and wet month parameters in the 2014-2015. The results of the processed image are then validated between in-situ measurements in the field and remote sensing imagery at the same time. This research utilizes descriptive analysis, and statistics with spatial approach. The results of the research show that temporally, chlorophyll-a levels have a tendency to be higher in wet months compared to dry months, while chlorophyll-a is higher in areas near the coastline compared to open sea areas. The distribution of chlorophyll-a concentration is affected by salinity and TSS distribution, where salinity has the negative relationship and TSS has the positive relationship with chlorophyll-a distribution.

Surface Stokes drift in the Baltic Sea based on modelled wave spectra

The Stokes drift is an important component in the surface drift. We used the wave model WAM to evaluate the mean values and exceedance probabilities of the surface Stokes drift in the Baltic Sea. As there is no direct way to verify the accuracy of the modelled Stokes drift, we compared the bulk parameters calculated by the wave model against buoy measurements to ensure the quality of the wave hindcast. Furthermore, we evaluated the surface Stokes drift from measured wave spectra to assess the accuracy of the modelled surface Stokes drift. The importance of the Stokes drift as a component of the total surface drift was evaluated by calculating the hindcast mean values and percentiles of the surface Stokes drift. The mean values were between 0.08 and 0.10 ms−1 in the open sea areas, thus being of the same order of magnitude as the mean wind shear currents. The highest values of the surface Stokes drift were slightly larger than 0.6 ms−1. The comparison of modelled Stokes drift values to estimates obtained from measured spectra suggests that the mean values are well represented by the model. However, the higher modelled values are most likely slightly too large because the wave energy was overestimated during high wind situations in some of the sub-basins, such as the Gulf of Finland. A comparison to a drifter experiment showed that use of the Stokes drift improves the estimate of both the drift speed and the direction in the Gulf of Finland. Parameterised methods to evaluate the Stokes drift that are used, e.g. in currently available Baltic Sea drift models, overestimate the smaller values (under 0.3 ms−1) and underestimate the larger values of the Stokes drift compared to the values calculated by the wave model. The modelled surface Stokes drift direction mostly followed the forcing wind direction. This was the case even in the Gulf of Finland, where the direction of the wind and the waves can differ considerably.

Holocene sea ice variability driven by wind and polynya efficiency in the Ross Sea

The causes of the recent increase in Antarctic sea ice extent, characterised by large regional contrasts and decadal variations, remain unclear. In the Ross Sea, where such a sea ice increase is reported, 50% of the sea ice is produced within wind-sustained latent-heat polynyas. Combining information from marine diatom records and sea salt sodium and water isotope ice core records, we here document contrasting patterns in sea ice variations between coastal and open sea areas in Western Ross Sea over the current interglacial period. Since about 3600 years before present, an increase in the efficiency of regional latent-heat polynyas resulted in more coastal sea ice, while sea ice extent decreased overall. These past changes coincide with remarkable optima or minima in the abundances of penguins, silverfish and seal remains, confirming the high sensitivity of marine ecosystems to environmental and especially coastal sea ice conditions.

Development and sea trial of real-time offshore pipeline installation monitoring system

Deep-water or open sea area developments bring technology challenges to offshore pipeline installation safeties. With low oil price, offshore contractors endure considerable pressure and struggle to provide cost-effective services. To achieve safe operations with higher efficiencies, it is essential to acquire better understanding of pipeline conditions in-process, which benefits operation planning and decision making. Offshore operational window and pipeline fatigue damage significantly depends on vessel motions. Current engineering practices generally predict motions through metocean and hydrodynamics based numerical simulations. This approach is useful but naturally leads itself to prediction uncertainties, which are most likely conservatism. With deep-water and open sea application, the uncertainties may become underestimations of key parameters due to possibly insufficient metocean data and inapplicable hydrodynamic methods. Subsequently, a real-time offshore pipeline installation monitoring system has been developed to predict realistic pipeline behavior by adoption of real-time operation parameters including vessel motions. A sea-trial for the system has been conducted on a pipelay project in 2016. As an alternative treatment to pipeline installation planning and decision making, the system has been proven capable of accurate simulations and additional functions such as touch point monitoring and fatigue tracking.

Mediterranean banks in EBSA area: Hotspots of biodiversity under threat

This study demonstrates that, in the Central Mediterranean Sea, the Graham, Nereo and Pantelleria Vecchia Banks of the Strait of Sicily represent, in the wide and diversified ‘Sicily Channel’ Ecological or Biological Significant Area, unknown hot spots of biodiversity threatened by human activities. The investigated banks show an high ecological and biological value (EBV), assessed through presence/absence of specific indicators. The ecological groups of Graham Bank show the maximum EBV; the same as Nereo and Pantelleria Vecchia, except for the benthic component. All three banks are highly threatened, mainly the benthic and benthopelagic ecological groups. However, these Banks still have wide pristine areas to protect and can be considered eligible sites for the imposition of area-based management measures of conservation. This study represent also a support for decision makers involved in protection of the Mediterranean open sea areas, to pinpoint other priority conservation banks.

Concentrations and origin of polycyclic aromatic hydrocarbons in sediments of the Middle Adriatic Sea

A total of 208 polycyclic aromatic compounds and their substituted homologues were investigated on eight stations along Croatia-Italy transect in the Middle Adriatic. PAC concentrations were higher in the coastal area than in the open sea area. The highest PAC concentrations were measured in the vicinity of the industrial harbor of Split while the lowest concentrations were observed on stations located in the open sea area. Polycyclic aromatic hydrocarbons were dominant group of compounds on each investigated station with contributions in total PAC concentration of more than 85%. S-PAH concentrations were higher than O-PAH concentration in each sample and tend to decrease as the distance from the coast increased. Contributions of O-PAH in total PAC concentrations were higher in the open sea sediments while S-PAH contributions were higher in the coastal sediment, indicating a different origin of O-PAH. Grain size analysis of the investigated sediments shows the dominance of fine fraction in sediments in the coastal area whereas sandy particles were a dominant fraction in the open sea sediments. TOC concentrations were higher in the open sea area where lower PAH concentrations were observed, indicating a different origin of PAC and TOC. PAH origin was evaluated by application of diagnostic ratios. Pyrogenic origin was determined only on one station whereas dominance of petrogenic PAHs was observed on the most of the stations in the open sea area. Marine traffic was suspected to be the main source of pollution in the open sea area.

Короткопериодная изменчивость метазойного микрозоопланктона в прибрежье Чёрного моря: закономерности и определяющие факторы

Метазойный микрозоопланктон (ММЗП) играет важную роль в выживании и питании личинок и мальков многих видов рыб, в том числе промысловых. Изучение изменчивости численности и структуры сообщества ММЗП в прибрежье Чёрного моря на масштабах времени дни — недели в ответ на вариации гидроклиматических факторов (температуры воды, силы и направления ветра и др.) весьма актуально, поскольку ранее подобных исследований микрозоопланктона не проводилось. Данные получены при ежедневном отборе проб в устье бухты Севастопольская с 13 мая по 21 июня 2013 г. в начальный период весенне-летнего возрастания численности ММЗП. Зоопланктон собирали 10-литровым пластиковым пробоотборником из поверхностного слоя моря. Пробы микрозоопланктона концентрировали методом обратной фильтрации и обрабатывали тотально в камере Богорова под микроскопом МБС-9. Наблюдавшееся в ходе исследований увеличение численности зоопланк-тона происходило на фоне повышения температуры воды и определялось ростом обилия рачковой фракции ММЗП и копепод как основной её части. Основной тренд изменений численности, определяемый температурой, модулировался кратковременными изменениями силы и направления ветра, приводившими к перераспределению численности и видового состава ММЗП в поверхностном слое. Одним из возможных механизмов такого перераспределения может являться различие поведенческих реакций планктеров на турбулентность водной среды, вызываемой ветром. Основой видового разнообразия ММЗП являлись науплиальные и ранние копеподитные стадии копепод родов Acartia, Oithona, Paracalanus, Centropages, науплиусы и копеподиты Harpacticoida, велигеры двустворчатых и брюхоногих моллюсков, личинки оболочника Oikopleura dioica, науплиусы усоногих раков, личинки полихет. Изменения структуры сообщества включают две стадии, характеризующиеся умеренно высокими или низкими индексами видового разнообразия и соответствующие периодам до и во время массового развития копеподы-вселенца Oithona davisae.

Simulation of the effect of an oil refining project on the water environment using the MIKE 21 model

A case study of the Caofeidian oil refining project is conducted. A two-dimensional convective dispersion mathematical model is established to simulate the increase in the concentration of pollutants resulting from the wastewater discharge from the Caofeidian oil refining project and to analyze the characteristics of the dispersion of pollutants after wastewater is discharged and the effect of the wastewater discharge on the surrounding sea areas. The results demonstrate the following: (1) The Caofeidian sea area has strong tidal currents, which are significantly affected by the terrain. There are significant differences in the tidal current velocity and the direction between the deep-water areas and the shoals. The direction of the tidal currents in the deep-water areas is essentially parallel to the contour lines of the sea areas. Onshore currents and rip currents submerging the shoals are the dominant currents in the shoals. (2) The pollutant concentration field in the offshore areas changes periodically with the movement of the tidal current. The dilution and dispersion of pollutants are affected by the ocean currents in different tidal periods. The turbulent dispersion of pollutants is the most intense when a neap tide ebbs, followed by when a neap tide rises, when a spring tide ebbs and when a spring tide rises. (3) There are relatively good hydrodynamic conditions near the project's wastewater discharge outlet. Wastewater is well diluted after being discharged. Areas with high concentrations of pollutants are concentrated near the wastewater discharge outlet and the offshore areas. These pollutants migrate southwestward with the flood tidal current and northeastward with the ebb tidal current and have no significant impact on the protection targets in the open sea areas and nearby sea areas.

Urban Change Detection of Pingtan City based on Bi-temporal Remote Sensing Images

In this paper, a pair of SPOT 5-6 images with the resolution of 0.5m is selected. An object-oriented classification method is used to the two images and five classes of ground features were identified as man-made objects, farmland, forest, waterbody and unutilized land. An auxiliary ASTER GDEM was used to improve the classification accuracy. And the change detection based on the classification results was performed. Accuracy assessment was carried out finally. Consequently, satisfactory results were obtained. The results show that great changes of the Pingtan city have been detected as the expansion of the city area and the intensity increase of man-made buildings, roads and other infrastructures with the establishment of Pingtan comprehensive experimental zone. Wide range of open sea area along the island coast zones has been reclaimed for port and CBDs construction.