Forms of metals in the littoral sediments in Kandalaksha Bay of the White Sea in the Russian Arctic

According to the results of the comparative study performed of the littoral sediments sampled in small inlets of Kandalaksha Bay (the White Sea in the Russian Arctic), the metals (Fe, Mn, Cu, Zn, Pb, Cr, and Li) occur mainly in a biogeochemical-stable mineral-incorporated form, which comprises 77–99% of the total metal content. The ratio of the liable form, which is easily extracted by a weak acid, is on average 3.2% for the total Fe, 2.0% for Mn, 1.7% for Cr, 5.6% for Pb, 5.8% for Zn, 6.5% for Cu, and is negligible for Li. The concentrations of the most studied trace metals are below the threshold level according to the environmental quality guidelines (the sediment analysis). The ratio of the metal forms evidences the natural origin of the elevated concentrations of both Zn and Cr in the sediments.     

Geochemical peculiarities of sediments in the northeastern Black Sea

We present the results of chemical determinations of Al, Fe, Mn, Cu, Ni, Co, Cr, Pb, Sb, and As in Black Sea sediments over a profile from the Kerch Strait to the eastern part of a deep depression (2210 m). The lithological and geochemical variations were studied in the horizontal and vertical profiles of sediments up to 3 m thick. The tendencies in the distributions of the studied metals during Pleistocene and Holocene sedimentation were analyzed beginning from Neoeuxinian freshwater deposits via the overlaying Drevnechernomorian beds with elevated contents of sapropel to modern clayey carbonate deposits with coccolithophorids. Statistical factor analysis isolated five factors: two main factors (75% of the total dispersion) and three subordinate factors. The first leading biogenic factor (47% of dispersion) reflects the correlation between С_org, Cu, and Ni; the second terrigenous factor (28% of dispersion) combimes Fe, Al, Cr, and Sb. The chemical composition of the sediments reflects the manifestation of diagenesis of landslide processes and mud volcanism along with sedimentation regularities.     

Harpacticoida taxocen diversity in the silty-sandy littoral zone of Kandalaksha Bay of the White Sea

The fauna composition, ecological groups, and life forms of Harpacticoids of soft littoral grounds from 15 sites off the Karelian coast in Kandalaksha Bay of the White Sea were studied. Six types of harpacticoid taxocens with different sets of dominating species are described. On silty sands with clear signs of desalination, the Stenchelia palustris taxocen is common; medium-grained sands are characterized by the Heterolaophonte minuta, Paraleptastacus kliei — Huntemannia jadensis, and Amphiascoides nanus — Scottopsyllus minor taxocens; while on coarse sands, the Ameira parvula and Ameira scotti — Mesochra lilljeborgi taxocens have developed. The diversity of the taxocens is partly explained by the differences in the grain-size composition and salinity at different sites. In addition, groups of various taxocens dwelling on the same type of the sediments were found in different minor bights of the coastline.     

Dinoflagellate cysts in the surface sediments of the White Sea

Dinoflagellate cysts were studied in 42 samples from the surface sediments of the White Sea. The total concentration of dinocysts varies from single cysts to 25 000 cyst/g of dry sediments, which reflects the biological productivity in the White Sea waters and the regional particular features of the sedimentation processes. The highest concentrations are observed in silts; they are related to the regions of propagation of the highly productive Barents Sea waters in the White Sea. Generally, the spatial distribution of dinocysts species in the surface sediments corresponds to the distribution of the major types of water masses in the White Sea. The cysts of the relatively warm-water species (Operculodinium centrocarpum, Spiniferites sp.) of North Atlantic origin that dominate in the sediments indicate an intensive intrusion of the Barents Sea water masses to the White Sea along with hydrological dwelling conditions in the White Sea favorable for the development of these species during their vegetation period. The cold-water dinocyst assemblage (Islandinium minutum, Polykrikos sp.) is rather strictly confined to the inner parts of shallow-water bays, firstly, those adjacent to the Onega and Severnaya Dvina river mouths.     

Dissipation of baroclinic tidal energy and diapycnal mixing in the White Sea

The modeling results obtained using the original version of the three-dimensional finite-element hydrostatic model QUODDY-4 testify that the spatial distributions of dissipation of baroclinic tidal energy and the related coefficient of diapycnal mixing in the deepwater stratified subdomain of the White Sea (the Basin and Kandalaksha and Dvina bays together) are highly similar to those found for low- and midlatitude oceans. It is in the open part of the sea that their values remain equal to the minimum possible values determined by the molecular kinematic viscosity; at its lateral boundaries (not all boundaries, but only individual segments (sites of mixing)), their values increase. In the shallow homogeneous subdomain of the White Sea, the dissipation of baroclinic tidal energy is considerably larger than in the deep stratified subdomain. Accordingly, the vertical eddy viscosity in the first subdomain is a few orders of magnitude higher than the coefficient of diapycnal mixing in the second subdomain. This is caused by an increased tidal velocity due to reduced depths.     

东大港与豆腐渣腰门交汇区潮流动力特征分析

对江苏省辐射沙洲海域东大港与豆腐渣水道交汇处5号站位连续两个潮次流速测量资料进行分析,对该交汇区域的潮流特征和潮流过程有了近一步认识,拟合给出了潮汐过程流速垂线分布表达式。     

Mineral composition of the modern bottom sediments of the White Sea

The mineral composition of the modern bottom sediments were studied in the White Sea. The single terrigenous-mineralogical province is defined; it is characterized by the mineral association of amphibole, epidote, garnet, and pyroxene. Five regions are assigned in the White Sea in accordance with the mineral composition of the surface bottom sediments. We argue that the granite-metamorphic rock complexes of the Baltic Shield are the main source of the modern sediments in the White Sea, while the East European Craton (Russian Platform) plays a secondary role.     

Hydrocarbons in the snow-ice cover of different areas of the White Sea

The data on the content of hydrocarbons (HC) are presented and compared to the contents of organic carbon, lipids, and particulate matter in the snow-ice cover of the coastal areas of Dvina and Kandalaksha bays of the White Sea (2008–2012). The accumulation of HC in the snow-ice cover depends on the degree of atmosphere contamination, the conditions of the ice formation, and the intensity of the biogeochemical processes at the ice-water interface. Because of this, the aquatic area of Arkhangelsk is characterized by the highest HC concentrations in the snow and in the upper layer of ice. The peculiarities of the formation of the snow-ice cover in Rugozero bight of Kandalaksha Bay cause the concentrating of HC in different layers of ice. The decrease of the concentration of HC in the show-ice cover of the White Sea compared to earlier studies resulted from the recession of industrial activities during the recent years.     

Holocene Paleoseismic Deformations on the Islands of the Kuzokotsky Archipelago (Kandalaksha Bay of the White Sea,Eastern Fennoscandia)

Izvestiya, Atmospheric and Oceanic Physics - Detailed paleoseismogeological, morphotectonic, and tectonophysical studies using remote and ground surveys have been carried out on the islands of the...     

Clay mineral distribution in sediments of the Gulf of Thailand and the South China Sea

The 25 sediment samples collected from the Gulf of Thailand and the South China Sea were analyzed for clay mineral investigation. Results showed the presence of 35% montmorillonite, 13% chlorite, 30% illite, and 22% kaolinite in sediments of the Gulf and also 16% montmorillonite, 21% chlorite, 41% illite, and 22% kaolinite in sediments of the South China Sea. The relatively high concentration of montmorillonite in sediments of the Gulf as compared with that in sediments of the South China Sea may suggest that montmorillonite in these area has been largely derived from soil formation of the bordering land areas of the Gulf, particularly from the northern part of Malay Peninsula. On the contrary, the content of illite in sediments of the South China Sea is higher than that in the Gulf. This mineral appears to have been supplied from Borneo as well as the Mekong Delta. However, chlorite which shows a similar distribution to that of illite in sediments of the Gulf and the South China Sea has not indicated Borneo Isl. as a principal source area for chlorite. Greater resemblance in amount of kaolinite in both sediments of the Gulf and the South China Sea is due to the prevailing distribution of kaolinite as low latitude clay mineral on the bordering land areas. The distribution of clay minerals in sediments of the study area appears to be closely related to the soil formation and geology of the adjacent land areas.This work was carried out at Geological and Mineralogical Institute, Tokyo University of Education.     

南黄海沿岸滩涂文蛤中痕量硒的周年变化探讨

采用4︰1混合酸湿法消解,氢化物发生原子荧光光谱法(HG-AFS)测定了南黄海沿岸滩涂文蛤生物体中微量元素硒的周年变化,并用质控样和加标回收保证结果的可靠性。结果显示:硒的周年含量为0.2~0.5 mg/kg,平均值为0.330 mg/kg,文蛤体内硒的含量呈一定规律性变化,春、秋季高,夏、冬季低。说明文蛤中硒含量因不同季节而具有明显差异,其含量变化与海水温度、饵料生物及文蛤生长繁殖等因素有关。     

Severity of sea ice in the Southern Baltic Sea, Gulf of Finland and Gulf of Bothnia up 21st century

The study focused on the evaluation of probable changes in the severity of sea ice conditions occurring in 3 selected areas of the Baltic Sea: the Gulf of Bothnia, Gulf of Finland and the Southern Baltic Sea up to the year 2100. The areas have been chosen due to the high intensity of marine traffic (the Gulfs??of Bothnia and of Finland) and due to differences in sea ice conditions; winters in the Gulf of Bothnia were characterized as the most severe, whereas in the Southern Baltic were classified as the mildest ones. Consequently, three scenarios were taken into account in the study: A2 (slow rate of global economic development, market scenario), A1B (regional scenario, rapid economic development, with ecological priorities), B1 (sustainable, median economic development with strong ecological priorities), all three constructed on the basis of Special Report on Emissions Scenarios (SRES models of greenhouse gas emission). The probable changes of sea ice conditions expressed as severity index S were calculated from these models. The main results of the investigation are as follows, the variety of sea ice conditions occurring in specific regions of the Baltic will remain stable (i.e. the most severe winter conditions will still occur in Gulf of Bothnia, while the mildest in the Southern Baltic Sea). The most significant changes are likely to occur in the Southern Baltic, where some winters without ice cover in the Vistula Lagoon may happen. Nonetheless, some extremely severe winters will occur and also within specific seasons more winters with a lower number of days with ice will occur.     

Tidal ice drift in the White Sea: Results of a numerical experiment

The tidal ice drift is considered as an element of the tidal dynamics in a sea covered with ice. The appropriate problem is solved with the use of a combination of a simple viscoelastic continuum model of the tidal ice drift with the QUODDY-4 three-dimensional finite-element hydro-thermodynamical model. The combined model is used for simultaneous calculations of the tidal regime and the tidal ice drift in the White Sea. The calculated distributions of the characteristics of the semidiurnal (M₂ wave) tidal ice drift such as the ice drift velocity and the tidal variations of the ice concentration and the pressure of the ice compression are discussed. The distributions are used for detecting the zones of the quasi-steady tidal compression and extension of ice and regions of ridging of ice floes. Particular attention is paid to the residual tidal ice drift, a phenomenon that has remained almost unnoticed so far.     

Iron and inorganic carbon in Liaodong Gulf sediments of Bohai Sea in China

1Introduction Ithasbeenapprovedthatoceanisthenetsink foratmosphericcarbondioxide(Sabineetal.,2000;Milleretal.,2002;Takahashietal.,2002;DeGrandpreetal.,2002;Song,2004).Thereare twoprincipalwaysinwhichcarbonisdrawndown fromthesurfaceocean:thereductionofinor…     

杭州湾北岸岸滩冲淤演变浅析

收集了1976～2004年杭州湾北岸的多幅地形图,使用ARCGIS软件进行数字化处理,以这些资料为主要依据对杭州湾北岸岸滩冲淤的历史演变和近期演变特征及其影响因素进行了分析.结果表明:(1) 历史上杭州湾北冲南淤,其北岸经历了先侵蚀后淤涨的过程.(2) 由于圈淤围垦,近30年杭州湾北岸岸线全线外移.(3) 近30多年杭州湾北岸的冲淤演变:1997年前芦潮港至南奉边界岸滩基本处于淤积状态,1997年后基本处于冲刷状态;金山岸滩基本处于稳定状态;金山嘴-金山卫滩涂一直比较稳定;漕泾-金山嘴滩涂经历了一个冲刷-淤积-再冲刷的过程,但冲淤幅度不大;奉贤部分岸滩处于侵蚀状态,1997～2004年0 m等深线以上岸滩进入侵蚀状态,侵蚀带由东向西推进,同时也向岸北侵,使-5 m等深线以下滩坡侵蚀变成-5 m等深线以上滩坡侵蚀.杭州湾北岸岸滩冲淤受多种动力因子的影响,除受潮流和风浪等动力因子的作用外,南汇边滩和杭州湾北岸围垦工程的影响及长江来沙量的减少是造成杭州湾北岸岸滩冲刷的两个重要因素.     

Expected changes in the benthic fauna of Wadden Sea tidal flats as a result of sea-level rise or bottom subsidence

In different parts of the Dutch Wadden Sea, relationships between intertidal level and abundance of marine macrozoobenthos were similar. Numerical densities, biomass and species richness increased from values close to 0 at the high-water level to maximum values around mean-tide level (numbers) or halfway between this level and low-tide level (biomass). Species richness hardly declined below mean-tide level, whereas mean weight per individual continued to increase from high- to low-water level.Biomass was about 45 g ash-free dry weight per m² at its maximum and declined in an approximately linear way to values close to 0 at the high-water level and to about 7 g per m² at the low-water level. These two linear relationships were used to predict biomass changes on intertidal flats of the Wadden Sea at various scenarios of sea-level rise and bottom subsidence. Net sea-level rise is expected to result in increased amounts of intertidal zoobenthos in areas with predominantly high tidal flats, but in declines in lower areas. However, such changes will occur only if sea-level rise proceeds too fast to be compensated by extra sedimentation. Bottom subsidence as a consequence of gas extraction is expected to be too small to cause any measurable change in the benthic fauna.     

南海北部湾东部海域表层沉积物地球化学特征

通过对南海北部湾东部海域61 个站位表层沉积物粒度和地球化学组成的相关分析和因子分析,探讨了其空间分布特征、元素相关性以及元素组合特征, 揭示了元素在区域上的分布规律和主控因素。结果表明: 绝大多数常微量元素具有相似的平面分布特征, 而MnO、Zr、CaO 和Sr 空间变异系数较大,在部分区域出现了异常高值, 表明其沉积环境受到正常陆源沉积以外其他因素的影响。元素和Al₂O₃的比值分布特征表明, 广西和海南岛近岸沉积物主要由陆源碎屑沉积组成, 在潮汐和近岸径流作用下,由近岸向远海输送; 而研究区西部海域沉积物主要为来自红河的物质。元素相关分析和因子分析结果表明, 研究区表层沉积物中绝大多数常微量元素主要受沉积物粒度的控制; CaO 和Sr 含量主要受生物活动活跃程度控制; Zr 含量分布主要受控于源区母岩矿物组成以及自源区的搬运距离; 而MnO 含量则受陆源、海底热液以及自生作用等多种来源共同影响。     

北极楚科奇海海冰面积多年变化的研究

北极气候系统正在发生显著变化,其中,海冰面积和厚度的减小是其最主要的特征.楚科奇海是海冰面积变化最有代表性的区域.文章利用积累了9a的高分辨率海冰分布数据研究海冰面积的多年变化特征.结果表明,各年的冰情有显著的季节内变化,海冰面积距平曲线体现了不同时期海冰面积变化的动态过程.在1997~2005年间,楚科奇海海冰面积经历了轻(1997年)-重(2000~2001年)-轻(2002~2005年)的变化过程.9a的数据总体上体现了海冰面积减小的趋势,2005年的冰情呈现了历史新低.每年融冰期的长短与冰情轻重有密切的关系,冰轻年份融冰开始时间早,冻结结束时间晚.各年海冰面积最小值发生在9月下旬至10月初,各个年份海冰最小面积差别很大.有的年份只有4%,而重冰年可以大于50%.文章采用4个重要参数表达海冰多年变化.其中海冰面积指数反映了当年总体平均的海冰面积距平;海冰最小面积反映了融冰期海冰的极限情况;上一个冬季的气温积温也与翌年海冰面积有良好的关联;分析了风场对海冰的影响,表明风场在融冰期能够在短时间内改变海冰的覆盖面积.