福宁湾海域溢油扩散影响的数值模拟研究

应用非结构化网格形式的MIKE 21水动力模型及溢油模块建立福宁湾海域海工工程施工期溢油扩散的数学模型,对在静风、全年主导风及不利风等3种不同风况条件下,一个潮周期内包括涨憩、落急、落憩、涨急等4个典型潮时分别发生100 t燃料油持续泄露30 min的事故溢油工况进行溢油扩散数值模拟.分析显示,事故溢油在福宁湾海域的扩散过程主要受潮流和风的影响.计算结果给出了事故溢油发生后24 h内的影响范围及0. 05 mg/dm3油浓度(一类或二类水质标准)溢油最快到达福宁湾内主要敏感目标的时间,为海洋环境影响评价和溢油事故应急措施的制定提供了科学依据.     

长江口深水航道内溢油轨迹的数值模拟

耦合海洋和溢油模型,建立起1个适用于长江口深水航道内溢油轨迹预报模型。海洋模型考虑了深水航道中导堤丁坝的影响,能够较好地模拟深水航道内流场,使物理场更加可信;溢油模型采用前国际上常用的随机游走和拉格朗日油粒子追踪法,预测油粒子的漂移扩散轨迹和扫海面积。研究表明:在深水航道中段发生的溢油事故,油粒子的漂移分布和扫海面积受导堤丁坝和流场的共同影响,涨急时刻溢油24h后油粒子的分布和扫海主要分布在导堤丁坝附近,落急时刻溢油的油粒子则大部分分布于导堤丁坝外,扫海面积也比涨急时刻大,对九段沙自然保护敏感区域产生一定程度的潜在生态影响。本文用数值实验的方法验证了海洋模型中考虑导堤丁坝与不考虑导堤丁坝相比,溢油轨迹预测是有差别的,考虑了导堤丁坝会对油粒子在导堤丁坝附近的漂移和扩散起阻挡约束和聚集的作用,没有考虑导堤丁坝的溢油扫海面积增大。     

天津大港滨海湿地溢油漂移扩散数值模拟研究

利用MIKE-HD建立二维水动力模型,模拟分析夏季天津大港滨海湿地附近海域水动力特性,采用实测潮位、潮流数据对模拟计算结果进行验证。在获得水动力数据的基础上,针对南港工业区船舶通航量加大的趋势,利用MIKE-SA模块建立溢油扩散模型,对溢油事故进行预测。结果表明,在风、潮的综合影响下,低潮时刻溢油24 h后的扩散面积比高潮时刻大,其中SW常风情况下其扩散面积最大,达72.04 km2;当风向与潮流方向一致时,即本文中低潮时刻溢油,油膜中心运动速度最大,扩散面积也最大。     

大亚湾海域温排水三维数值模拟

为了研究大亚湾海域核电站温排水热污染问题,本文利用POM模式建立了大亚湾潮流三维数值模型,在模型验证良好的基础上,结合建立在对流扩散理论基础之上的输运扩散模型,对大亚湾核电站和岭澳核电站一期工程合排后夏季两核电站温排水的稀释扩散过程进行了数值计算,得到了涨憩、涨急、落憩、落急四个典型时刻温升场的特征值,并进一步分析了温升场的变化特征。     

长江口海域污染物入海扩散模拟研究

长江口地形复杂,水动力过程也极为复杂,模拟污染物的三维扩散也十分困难。本文基于三维海洋模型FVCOM和示踪剂扩散技术,模拟上海市石洞口、竹园、白龙港和新和4大排污口的污染物质在长江口的扩散分布,分析污染物在水体表层、中层、底层的扩散特性及其影响范围。研究表明长江口污染物的扩散在垂向上分布差异不大,在长江口内污染物由于受到长江径流影响较大,虽然水平分布存在往复运动的现象,但总体趋势是向长江口扩散的。当污染物流出长江口以后,受潮流的影响较大,逐渐向外海扩散,最终部分污染物会扩散进杭州湾,排污口的污染物质会对排污口沿岸、上海中华鲟自然保护区上海九段沙湿地国家级自然保护区造成生态影响,对上海市的饮用水源地不会造成影响。     

基于SPOT遥感影像的九段沙潮沟信息提取及分维研究

以长江口九段沙为研究区, 应用灰度形态学提取了九段沙湿地的潮沟信息, 并对提取出的潮沟信息分区域采用网格法进行了分维研究, 得出了九段沙不同区域潮沟的分维值, 并对分维值进行了比较与分析。比较发现, 九段沙不同区域的分维值, 上沙最大, 下沙次之, 中沙最小。而在不同区域的不同岸段中, 处于上沙北部沿岸的潮沟分维值大于上沙其它地区; 处于中沙、下沙西北-东南沿岸的潮沟分维值分别大于中沙、下沙的其它地区。这主要与它们所处地理位置水动力条件不同有关。另外也计算了九段沙南岸与北岸的分维值, 发现南岸的分维值要大于北岸, 这与其发育时间、水动力条件和长江口深水航道工程等有一定联系。     

基于遥感的九段沙湿地DEM构建及动态变化分析

对九段沙湿地1987年、2001年和2004年多个时相的Landsat遥感影像提取了多组水陆边界点，并依据四周4个潮位站的潮位观测值，用距离倒数权重法计算了各组边界点的高程。结合相应年份长江口海图九段沙区域的水深数据，构建了九段沙湿地3个年份的数字高程模型。统计对比分析结果表明，目前九段沙湿地0m线以下部位的淤积速度显著下降，-6m线部位已开始蚀退；另一方面，0m线及以上湿地部位的淤积速度仍有所加快。     

九段沙上沙南沿坍塌与外沙内泓效应

利用1986~2013年的长江口海图以及2013年九段沙上沙南沿的冲淤观测数据,分析了外沙内泓地形形成机理以及凸显的效应。长江口深水航道治理工程改变了九段沙湿地局部边界条件,导致江亚南沙沙尾下延,深泓线北移,上沙南沿坍塌后退。建议采取护滩工程措施,保护上沙湿地资源。     

黄河口湿地潜在溢油污染生态风险评估

黄河口有着我国典型的新生湿地生态系统,生态环境非常脆弱,极易受到陆源和海洋污染事故的影响。本文针对黄河口附近海上油田的开发和运输带来的潜在溢油风险,结合溢油污染概率模型以及河口的生态脆弱性,对黄河口湿地潜在溢油污染风险进行评估。在河口水动力模拟的基础上,采用随机情景模拟法选取300种风和潮流组合作为溢油模拟的强迫条件,分别模拟溢油后72 h和720 h的污染结果,并统计黄河口湿地受溢油污染影响的最大概率和最短时间,采用环境敏感指数表征湿地对溢油污染的敏感程度、危害后果指数量化表征其危害程度及风险矩阵量化风险高低。结果表明黄河口国家公园受潜在溢油污染概率较大,危害后果指数值为29,处于较高危害等级,属于中风险区;河口岸线受潜在溢油污染概率较小,危害后果指数值均小于1,溢油危害后果低,属于低风险区。     

2004年春季长江河口水体与沉积物表层的叶绿素a浓度分布

2004年5月7日至12日在31°~31.8°N、122.5°E以西到海水上溯至0盐度的长江河口进行14个站位叶绿素a浓度的现场观测,其中N1~N3、M1~M3、S1~S3和R6这10个观测站用3条渔船在4天内进行潮周期的涨憩、落急、落憩、涨急、涨憩5个潮时的准同步周日采样观测;对S2、S3、R2、R3、M3、N2和N3这7个位于长江入海口门站位进行表层泥样的叶绿素a浓度观测。结果表明,观测海区表层海水叶绿素a浓度为0.230~11.500μg/dm3,平均值为(1.514±1.712)μg/dm3,高值出现在观测海区东北部的长江冲淡水稀释区,表层海水叶绿素a浓度平面分布从该区的东北部向西南方向逐渐降低,离岸越近叶绿素a浓度越低,低值出现在长江口门内和测区西南部的广阔浑水区域;底层叶绿素a浓度为0.291~2.620μg/dm3,平均值为(1.186±0.531)μg/dm3,其变化幅度与平均浓度均明显低于表层。在涨憩、落急、落憩、涨急和涨憩5个潮周期中水柱平均叶绿素a浓度为1.198~1.910μg/dm3,涨憩和落急潮时,叶绿素a浓度自表层向底层逐渐下降;落憩和涨急潮时,表层的平均叶绿素a浓度略低于中层和底层。2004年春季观测海区叶绿素a浓度与往年夏季和秋季的观测结果相近,但明显高于冬季。表层沉积物叶绿素a浓度为(0.089±0.052)μg/g(湿重),仅占其上方水体平均叶绿素a浓度的极少部分,两者具有良好的相关性。     

Model of the post-Cenozoic evolution of the cryolithozone of the shelf of the western part of the Laptev Sea

The analysis of the structure of the cryolithozone, facies, and thicknesses of the Quaternary sediments and the results of the physicochemical mathematical modeling of the modern shelf of the western part of the Laptev Sea support the influence of the Late Pleistocene glaciations on the heat conditions and the distribution of the permafrost in the area. A ～200-m thick glacier formed under aerial conditions from atmospheric precipitation represented the metamorphosed snow cover. According to the modeling, the long-living (from 60?50 to 10?4 ky) glacier reduced the thickness of the permafrost rocks in the reviewed shelf area for 280–360 m. The Holocene marine transgression additionally decreased the thickness from 50–140 m on the inner shelf to 220–350 m on the outer shelf. The modern submarine cryolithozone 450-0 m thick is wide-spread in the studied region from the coast to the shelf boundary (isobaths of 130–140 m), where it pinches out at a distance of ～380 km from the coast at a depth of ～250 m above the sea level.     

Investigation of the mechanism of the long-term evolution of the carbon cycle in the ecosystem of the Sevastopol bay

We analyze the components of the carbon system of the Sevastopol bay waters and the balance of main sediment-forming substances using the data of field investigations in 1998–2008. The interannual variations of total inorganic carbon and the equilibrium partial pressure of carbon dioxide in the bay water are noted. An increase in the flux of carbon dioxide into the bay and in the content of organic carbon in bottom sediments is revealed, and an explanation of this phenomenon is given. The priority accumulation of organic carbon in the sediments of the bay is established. We assess the interannual variation in the relative abundances of organic and inorganic carbon as an index of the carbon cycle stability.     

Contemporary state of the investigation of the influence of the discharge of rivers on the hydrologic structure of the Black Sea

We generalize and analyze the state of investigations of the influence of river waters on the hydrologic structure of the Black Sea. Specific features of the water, regime and hydrography of rivers flowing into the sea, data on the discharge of rivers, and intrayear and interyear variability of the discharge are presented. We discuss and analyze works studying the transformation of river waters, routes of desalinized sea waters, and their influence on the thermohaline structure and dynamic regime of the sea. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Modelling of the ecosystem of the Black-Sea shelf zone near the estuary of the Danube

We analyze the results of numerical calculations performed according to the three-dimensional interdisciplinary model of an ecological system of the Black-Sea shelf zone near the estuary of the Danube. The complete system of equations of hydrothermodynamics is solved together with transport equations of the advection-diffusion-reaction type used to describe the transformation of a substance (nitrogen) between the components of the characteristic vectors of the ecosystem: plankton, detritus, and biogenic elements (nitrates). We describe the distinctive features of the circumcontinental distribution of components obtained as a result of numerical experiments and present arguments for the conclusion that the ecosystem of the Danube estuary water area plays the role of a buffer zone between the press of the Danubian biogenic pollutions and the neighbouring areas of the shelf zone and open sea. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Relationship between the path of the Kuroshio in the south of Japan and the path of the Kuroshio Extension in the east

A relationship between paths of the Kuroshio and Kuroshio Extension (KE) is investigated, using the satellite-derived altimetry dataset of 1993–2008. When the Kuroshio takes the nearshore nonlarge meander path or typical large meander path and resultantly goes through the deeper channel (about 2500 m) of the Izu-Ogasawara Ridge, the KE path adopts a relatively stable state with the two quasi-stationary meanders. On the other hand, when the Kuroshio takes the offshore nonlarge meander path and then passes over the shallower part of the Ridge (about 1000 m), the KE path tends to be convoluted, i.e., an unstable state.     

Dynamics of the ice cover and peculiarities of the ice transportation of the sediments at the tidal flats of the Kandalaksha Gulf of the White Sea

Ten years of semistationary studies of the interaction of the ice cover and the coastal relief of the Kandalakhsa Gulf in the White Sea allowed us to reveal the peculiarities of these processes in the warm and cold years and the mechanisms of the origination of ice forms, including ice tents, which govern the character of the tidal flats. Three dynamic fast ice zones are distinguished by their geomorphological location, morphology, and ice dynamics. The dependence of the mechanisms and volumes of the enrichment of the fast ice in the sediments on the coastal zone??s relief was established. At the coast of the Kindo Peninsula (Velikaya Salma Strait), the ice mostly contains fine-sandy sediments. Coarser sediments, including boulders, are occasional and frozen into the ice at the contact of the fast ice and the bottom. At the expense of the ice??s spreading by 4?C6 times in the warm years and 2?C4 times in the cold years, several thousand tons of sediments mostly from the tidal flat??s surface (100?C700 m³ from 1 km of coast in the wide tidal flats and <50 m³ on the steep coasts) are delivered to the water area.     

Parameters of the sediments of the deep-water basin of the Black Sea

The methodology and the first results of the computations of the volumes, masses, and growth rates of the sedimentary body of the buried Black Sea basin are presented. Their temporal evolution reflects the regional paleogeodynamics, in particular, the reorientation of the vector of the relative movement of the Arabian and Eurasian lithospheric plates and the related intensification of their collision in the late Miocene-Pliocene.     

Variability of the nutrient runoff of the rivers of the Arctic Basin

The spatiotemporal variability of the hydrochemical composition of the riverine runoff in nearmouth areas is presented using the example of selected rivers of the Arctic Basin. The temporal dynamics of the riverine nutrient runoff are mainly determined by the seasonal and interseasonal variations in the drainage basins. The spatial variations in the chemical composition of riverine waters in the near-mouth areas are mainly caused by the dynamics of the water flow and the river bed relief and, to a lesser degree, by biochemical processes. It is shown that the variations in the nutrient composition of the waters in near-mouth areas are comparable in magnitude to those at the river-sea geochemical barriers.     

A model of the dynamics of the ecosystem of the Sea of Azov

We use many-year archival observations of hydrologic and hydrobiologic state of the Sea of Azov for the identification of the structure of a model of its ecosystem. The ecosystem model, supplemented with expert estimates of bioresource consumption (fish reserve), contamination level, and possible ecologic fines for violation of the sea natural state, is formalized by the method of system dynamics. Hereat, the major part of influence functions is found in terms of observational data with application of self-organization algorithms. We also present the results of simulated experiments with the model of the ecosystem, which enable us to analyse scenarios of its behaviour under the influence of various external factors (wind, river discharge, water exchange with the Black Sea, etc.). Translated by Peter V. Malyshev and Dmitry V. Malyshev     

On the Relationship between the Characteristics of the Annual Variations of the Virtual Height of the Ionospheric Sporadic E Layer with the Seasonal Rearrangements of the Stratomesospheric Circulation

Izvestiya, Atmospheric and Oceanic Physics - Analysis of the temporal variations of the virtual heights of the sporadic E layer (h?ES) determined from ionograms with increased accuracy (1...