共查询到20条相似文献，搜索用时 31 毫秒
1.
Derek V. Ellis 《Marine Georesources & Geotechnology》2013,31(1):51-63
Abstract This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be site-specific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of “marine snow” (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
2.
深海采矿尾矿排放产生的细颗粒羽状流会对海底生态环境造成影响，预测尾矿排放羽状流行为及其对环境影响具有工程意义。基于欧拉多相流方法，采用欧拉双流体模型对深海采矿细颗粒羽状流开展数值模拟研究，分析近海底排放的羽状流演化和发展过程，探究羽状流初始排放质量浓度、排放速度对羽状流扩散过程的影响。结果表明：初始排放条件对羽状流演化性质有重要影响。主射流区被稀释的程度随着初始入射速度的增大而减小，随着入射质量浓度的增大而增大；初始羽状流入射速度和质量浓度越大，撞击海底后的水平方向流动速度越快，影响区域越广；水平速度的峰值随着初始入射速度的增大呈对数增长；当初始质量浓度和速度高于50 g/L和 0.5 m/s 时可能会导致颗粒在海底撞击点附近堆积成坡状，影响底流的后续发展。研究结果可以为深海采矿尾矿排放参数选择提供参考。 相似文献
3.
4.
The East Sea, with an average depth of 1700 m, has long been subject to heavy fishing pressure, resulting in derelict fishing gear. Most derelict fishing gears, such as fishing nets, fishing ropes, and crab pots, sink to the seabed and do not degrade. This gear results in “ghost fishing,” which has adverse impacts on deep benthic habitats. Recently, the Korean government has started to remove derelict fishing gears from the deep seabed of the East Sea by bottom trawling with heavy hooks (50–80 kg) and ropes. A total of 207.8 and 252.2 tons of marine debris in 2009 and 2010, respectively, were removed from the seabed, most of which were derelict fishing gears. Contrary to monitoring surveys and clean-up in shallow waters, removal of marine debris from remote deep habitats is much more difficult and dangerous for removal crews. 相似文献
5.
Chan-Young Park Seung-Ho Park Choon-Woo Kim Jung-Keuk Kang Ki-Hyune Kim 《Marine Georesources & Geotechnology》1999,17(4):371-386
In order to develop the mineral resources contained in manganese nodules of the deep sea, the Korea Ocean Research & Development Institute (KORDI) has explored the area allocated by the United Nations in the Clarion-Clipperton Fracture Zone in the northeastern Pacific. During research cruises, the seabed surface was photographed every 30 s by the KORDI Deep Tow Imaging System (DTIS). Features such as the coverage and size distribution of manganese nodules on the photographs serve as the essential information to determine the potential mining areas. This article presents (semi)automatic procedures to extract the useful features from the photographs of the seabed surface using digital image processing techniques. The 35-mm films are first digitized by the film scanner. The depth information written on the film is then recognized to compensate for distortions due to nonuniform illumination. The nodule areas on the digitized image are recognized and separated from the background based on the characteristics of the nodules. The nodule coverage and distribution of nodule diameters are then calculated from the processed image. The proposed technique has been applied to sample photographs of the seabed surface. Experimental results indicate that the technique could be utilized as an efficient tool to process the massive collection of photographs of the seabed surface. 相似文献
6.
深海采矿系统中的长距离垂直输运管道在工作中具有复杂的流固耦合力学特性,在生产作业中其结构安全性和可靠性面临严峻考验。建立深海采矿系统从海底到水面的完整模型,采用集中质量法对于其中的长距离垂直输运管道的环境载荷进行了研究,并将计算结果与模型试验测量值进行对比验证,重点分析管道顶部轴向张力和剪力的大小关系以及变化规律。分析结果表明:在深海采矿系统的长距离垂直输运管道中,轴向张力在结构载荷占主要成分,由波浪引起的结构轴向张力增加会达到管体自重的38%～48%。因此,选择合适的作业工况对降低结构载荷,加强结构安全性能有很大帮助。 相似文献
7.
In the last few decades, considerable efforts have been devoted to the phenomenon of wave-induced liquefactions, because it is one of the most important factors for analysing the seabed and designing marine structures. Although numerous studies of wave-induced liquefaction have been carried out, comparatively little is known about the impact of liquefaction on marine structures. Furthermore, most previous researches have focused on complicated mathematical theories and some laboratory work. In the present study, a data dependent approach for the prediction of the wave-induced liquefaction depth in a porous seabed is proposed, based on a multi-artificial neural network (MANN) method. Numerical results indicate that the MANN model can provide an accurate prediction of the wave-induced maximum liquefaction depth with 10% of the original database. This study demonstrates the capacity of the proposed MANN model and provides coastal engineers with another effective tool to analyse the stability of the marine sediment. 相似文献
8.
Regular surveys of coastal zone seabed deliver important information about geomorphologic processes such as silting of waterways. The recent introduction of the Sentinel series of sensors has allowed for the use of satellite sensing for shallow bathymetry morphology monitoring. In this context, this article presents a dedicated Geographic Information System for Baltic Sea shallow water depth monitoring on the basis of Sentinel-2 imagery. The system employs Geovisual Analytics for differential analysis of bathymetry changes as well as monitoring the visibility of known wrecks in the coastal waters of Southern Baltic Sea. Results are verified with regard to known changes in shallow water bathymetry between 28 June 2015 and 3 March 2017. 相似文献
9.
《Marine Policy》2016
The 1982 United Nations Convention on the Law of the Sea declares the seabed beyond national jurisdiction and its mineral resources as the “common heritage of mankind” (CHM). This article examines the operationalisation of the CHM principle in the international seabed mining regime, with focus placed on the sharing of benefits derived from mining. The article begins by providing an overview of the CHM principle, before examining four modalities provided for in the Convention, both institutional and substantial, and their role in giving effect to the CHM principle: (1) financial benefits; (2) the “Enterprise”; (3) the parallel system of reserved areas; and, (4) marine scientific research. Finally, overarching issues are discussed and some suggestions on ways forward are presented. The article considers that the deep seabed mining regime is not yet ready to effectively share the benefits derived from the common heritage of mankind. In particular, the future of the Enterprise is uncertain and changes to the so-called parallel system that affect the CHM have received minimal discussion. Moreover, a lack of publicly available research data related to seabed mining is hindering current benefits for humankind. However, work is underway at the International Seabed Authority to establish rules and policies with respect to the sharing of financial benefits. While the CHM principle remains largely untested, approaches that are transparent, inclusive, accountable, and equitable are more likely to be successful. 相似文献
10.
Jacobus P. Le Roux Zeki Demirbilek Marysia Brodalka Burghard W. Flemming 《Geo-Marine Letters》2010,30(5):549-560
The generation and growth of waves in deep water is controlled by winds blowing over the sea surface. In fully developed sea
states, where winds and waves are in equilibrium, wave parameters may be calculated directly from the wind velocity. We provide
an Excel spreadsheet to compute the wave period, length, height and celerity, as well as horizontal and vertical particle
velocities for any water depth, bottom slope, and distance below the reference water level. The wave profile and propagation
can also be visualized for any water depth, modeling the sea surface change from sinusoidal to trochoidal and finally cnoidal
profiles into shallow water. Bedload entrainment is estimated under both the wave crest and the trough, using the horizontal
water particle velocity at the top of the boundary layer. The calculations are programmed in an Excel file called WAVECALC,
which is available online to authorized users. Although many of the recently published formulas are based on theoretical arguments,
the values agree well with several existing theories and limited field and laboratory observations. WAVECALC is a user-friendly
program intended for sedimentologists, coastal engineers and oceanographers, as well as marine ecologists and biologists.
It provides a rapid means to calculate many wave characteristics required in coastal and shallow marine studies, and can also
serve as an educational tool. 相似文献
11.
海岸带工程地质环境的稳定性对于海洋工程的建设安全和沿海经济繁荣十分重要。在胶州湾海域已有地质、水文等数据的基础上,对胶州湾海底工程环境适宜性进行了分区。通过无监督机器学习的谱聚类算法,构建了胶州湾海底工程环境适宜性综合评价模型。结果表明,胶州湾整体工程环境适宜性趋势为北高南低,从北向南依次可分为适宜性高、适宜性较高、适宜性较低和适宜性低四个区域。相关性分析表明,影响胶州湾海域海底工程适宜性的因素从高到低依次为冲淤分布、沉积物类型、坡度、第四系沉积物厚度、水深、海流流速、断裂分布。本研究可为胶州湾工程环境和地质灾害预防提供参考,有助于海洋工程环境稳定和经济安全保障。 相似文献
12.
A shallow gas depth-contour map covering the Skagerrak-western Baltic Sea region has been constructed using a relatively dense grid of existing shallow seismic lines. The digital map is stored as an ESRI® shape file in order to facilitate comparison with other data from the region. Free gas usually occurs in mud and sandy mud but is observed only when sediment thickness exceeds a certain threshold value, depending on the water depth of the area in question. Gassy sediments exist at all water depths from approx. 20 m in the coastal waters of the Kattegat to 360 m in the Skagerrak. In spite of the large difference in water depths, the depth of free gas below seabed varies only little within the region, indicating a relatively fast movement of methane in the gas phase towards the seabed compared to the rate of diffusion of dissolved methane. Seeps of old microbial methane occur in the northern Kattegat where a relatively thin cover of sandy sediments exists over shallow, glacially deformed Pleistocene marine sediments. Previous estimates of total methane escape from the area may be correct but the extrapolation of local methane seepage rate data to much larger areas on the continental shelf is probably not justified. Preliminary data on porewater chemistry were compared with the free gas depth contours in the Aarhus Bay area, which occasionally suffers from oxygen deficiency, in order to examine if acoustic gas mapping may be used for monitoring the condition of the bay. 相似文献
13.
经济发展影响下我国海洋环境污染压力变化趋势及污染减排对策分析 总被引：2，自引：0，他引：2
对20世纪90年代以来我国经济发展影响下的海洋环境污染变化趋势进行了分析,指出近年来我国海洋环境污染防治工作取得了一定成效,但近岸海域污染的总体形势依然严峻,并可能随着经济总量的增长而再次恶化,氮磷营养盐超标导致的海水富营养化是近岸海域的主要污染问题。讨论了我国现行的污染物减排策略对海洋污染防治的局限性,并以国家"十二五"发展规划、沿海区域社会经济发展规划为依据,综合分析"十二五"期间我国海洋环境污染防治面临的压力和主要入海污染源的排污特征,建议应对农业非点源开展源头污染控制、对沿海地区点源加强末端治理,实施流域-河口-海域联动的入海污染物减排策略。 相似文献
14.
春、秋季南黄海浮游纤毛虫丰度及生物量的分布差异 总被引：1，自引：0，他引：1
Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean.In this study,we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area(station depth greater than 60 m) and the coastal shallow area(station depth less than 60 m) of the southern Yellow Sea(32°–36.5°N,121°–125°E) in spring(April) and autumn(October–November) of 2006.Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring((1 490±2 336)ind./L;(4.11±7.81) μg/L) than in autumn((972±823) ind./L;(1.11±1.18) μg/L,calculated by carbon).Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn.However,in the central deep area,those values were much higher in spring((1 878±2 893) ind./L;(5.99±10.10)μg/L) than in autumn((738±373) ind./L;(0.74±0.76) μg/L).High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn.Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring,when a phytoplankton bloom occurred.However,in autumn,L.strobila was abundant in the coastal shallow area.Boreal tintinnid Ptychocyli obtusa was found in spring.Both L.strobila and P.obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L.Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L.This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally. 相似文献
15.
海洋灾害地质学发展的历史回顾及前景展望 总被引：1，自引：0，他引：1
海洋灾害地质学是近半个世纪以来逐步发展起来的1门新兴学科.本文论述了这一学科产生与发展的背景,简要回顾了国内外海洋灾害地质调查研究的历史,展望了学科的发展前景.作者认为,海洋灾害地质学学科的进一步发展,必需要融入“全球变化”和“全球系统科学”的概念;要加强海洋灾害地质学基础理论研究;既要重视海岸带灾害地质研究,又要面对... 相似文献
16.
N. Vedachalam S. Ramesh P. Udaya Prasanth G. A. Ramadass 《Marine Georesources & Geotechnology》2018,36(8):966-973
Natural gas hydrates is considered as a strategic unconventional clean hydrocarbon resource in the energy sector. Understanding the behavior of the rising methane gas bubbles during production leaks from the deep marine gas hydrate reservoirs well head is essential for environmental impact studies and to design environmental monitoring systems. Numerical model for quantitatively characterizing the vertical dissolution pattern of the wellhead released methane gas bubbles is analyzed for three potential gas hydrate locations in India. Simulation results indicate that the methane bubbles with diameter of 10?mm can transport methane gas till 650, 800, and 750?m from the seabed in the Krishna–Godavari(KG), Mahanadi and Andaman basins respectively. Results brought out that potential well head damage during methane hydrate production at 1050?m water depth could release up to 28?m3 of methane gas, in which 50% of the molar mass shall get dissolved within 40?m of water column from the seafloor. 相似文献
17.
Sulphidic mine waste disposed in marine environments constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in biota. Fiord sediments near the former Black Angel Mine in West Greenland are contaminated by lead and zinc as a result of submarine tailings disposal in 1973-1990. In 1999 cores were taken up to 10 km away from the disposal area. Analyses include heavy metals, radiochemical dating (210Pb) and high-resolution foraminiferal stratigraphy. The mining operation resulted in significant changes in the assemblage composition. In addition, up to 20% of the Melonis barleeanus population found in sediment deposited during nearby tailings disposal was deformed compared to a natural background of less than 5%. Throughout cores representing the last 100 years of sedimentation, the total numbers and frequency of morphological abnormalities among M. barleeanus revealed some correlation with heavy metals concentrations (up to r2 = 79%). We conclude that abnormalities among foraminifera may represent a useful biomarker for evaluating trends in the biological impact resulting of submarine tailings disposal as well as long-term environmental impact and subsequent recovery. 相似文献
18.
19.
《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(1):1-48
Reduced ice extent within coastal regions of the Southern Ocean may lead to deeper surface mixed layers (SML), as prevail in offshore areas. A future decline of ice melt-induced stability of the water column may be associated with a shift in dominant food webs, from larger, sun-adapted diatoms grazed by euphausiids to smaller, shade-adapted flagellates consumed by salps. A basically one-dimensional numerical model of three dominant groups of the Antarctic phytoplankton community (diatoms, cryptophytes, and colonial prymnesiophytes) and four types of herbivore (protozoans, salps, copepods, and euphausiids) is used to explore the seasonal importance of both light limitation and grazing pressure on the amount of annual carbon sequestration and larval krill survival within contrasting oceanic and neritic waters, where respective validation data have been gathered during austral spring by the European JGOFS and RACER programs. With imposition of moderate and large grazing stresses, thought to be typical of offshore waters, we were able to replicate the European JGOFS 1992 observations of light penetration, phytoplankton biomass, primary production, pCO2, bacterial biomass, labile DOC, ammonium, and total particle effluxes at 100 m within the deep SML of our model. The fidelity of such a large set of simulated state variables suggests that multiple limiting factors are indeed operating on different components of the oceanic phytoplankton community — selective grazing losses on the flagellates, but light limitation of diatoms. Release of protozoan grazing pressure in our model instead leads to unobserved spring blooms of cryptophytes, found only in laboratory enclosures. On an annual basis, weak sequestration of atmospheric CO2 is simulated in a habitat typical of the Polar Front, while evasion of carbon dioxide occurs under biophysical conditions of the Antarctic Circumpolar Current. Stratification in shallow SML and the same absolute grazing demands by krill and copepods allows sun-adapted diatoms of our model to bloom at the expense of shade-adapted cryptophytes and prymnesiophytes, eaten by salps and protozoans. We were also able to replicate RACER-I observations of the same suite of variables in 1986–1987, as well as the observed 10-fold range of detrital fluxes caught by other sediment trap deployments during 1980 and 1983 along the Antarctic Peninsula. In western Bransfield Strait, coastal waters are a strong sink for atmospheric CO2 within parcels of Bellingshausen Sea origin, but not perhaps in those from the Weddell Sea, which resemble the oceanic regime of deep SML. We conclude that even in shallow neritic SML, some protozoan rivals of larval krill must still crop flagellates to ensure sufficient abundance of diatom food for both euphausiid survival and possible clogging of the mucous nets of other salp rivals. 相似文献
20.
Synthesis of Environmental Impacts of Deep Seabed Mining 总被引：1，自引：0，他引：1
Charles L. Morgan Nii Allotey Odunton Anthony T. Jones 《Marine Georesources & Geotechnology》1999,17(4):307-356