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1.
The downward flux of Mn through the water column was directly measured using sediment traps. The Mn flux from the bottom sediment to the water column, and the removal rate of Mn in the bottom water were estimated from Mn gradients in the bottom water. The sediment traps were deployed more than ten times at the same station in Funka Bay, Japan. The trapped settling matter and filtered suspended matter samples were analyzed for Mn, Fe, Al and ignition loss. The observed downward flux of Mn through the water column in winter (1.3–2.8 μg/cm2 /day) was generally an order of magnitude larger than that in summer (0.13–0.45 μg/cm2 /day), and the Mn fluxes for both seasons were also greater than the accumulation rate of Mn in the bottom sediments (0.10 μg/cm 2/day). More Al was contained in the trapped settling matter than in the suspended matter, while Mn showed the opposite behavior. The Fe/Mn ratio of the residual fraction (obtained by subtracting the sediment component of the settling matter) was rather well correlated with the corresponding ratio in suspended matter. Settling particles are expected to scavenge suspended matter during their passage through the water column. The flux of Mn across the sediment—water interface was estimated from its vertical profiles in the water column to be 0.1–0.3 μg/cm2 day. The residence time of Mn in bottom water was about one to several months. These results suggest that Mn is actively recycled between the water column and the sediments of the coastal sea. 相似文献
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V. N. Lukashin 《Oceanology》2008,48(5):701-709
The sedimentation system of the bottom contour current over the continental slope of Bear Island in the Norwegian Sea is considered. The nepheloid layer that provides the high horizontal flux of sedimentary material represents the main source of matter for the bottom sediments. The vertical particulate matter flux is largely formed in the nepheloid layer; the flux from higher layers of the water column is insignificant. Horizontal and vertical fluxes of sedimentary matter show a positive correlation. The flux of the matter from the bottom sediment into the nepheloid matter and the residence time of particles in the latter are estimated. 相似文献
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Environmental impact factors and mercury speciation in the sediment along Fujian and eastern Guangdong coasts 总被引：1，自引：0，他引：1
ZHANG Yuanbiao HUO Yunlong LIU Xiyao KUANG Weiming YUAN Dongxing JI Weidong 《海洋学报(英文版)》2013,32(2):76-80
Concentrations of total mercury (THg) and methyl mercury (MeHg) were determined for 32 surface sediments collected along the coastal line of Fujian Province and eastern Guangdong Province. The spatial distributions of THg and MeHg and their environmental impact factors were investigated. The average concentrations of THg and MeHg in the sediments were 31.5 ng/g and 0.096 ng/g, respectively. Both sediment THg and MeHg concentrations showed relatively high value in the Minjiang Estuary and the coastal areas of Quanzhou and Putian. The concentrations overall decreased as the distance to the shoreline increased. The correlations among environmental impact factors and THg, MeHg were analyzed. The sediment THg concentration was highly correlated to the concentrations of organic matter, copper, total nitrogen (TN) and total phosphorus (TP), and significantly correlated to pH value of the bottom seawater and concentration of sediment sulfide. The sediment MeHg concentration was highly correlated to the concentrations of organic matter and copper, and significant correlated to the concentrations of sulfide, TN, TP and pH value of the bottom seawater. 相似文献
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潮流场对渤、黄、东海陆架底质分布的控制作用 总被引：10，自引：0，他引：10
朱玉荣 《海洋地质与第四纪地质》2001,21(2):7-13
运用二维潮流数学模型，模拟了渤、黄、东海陆架的M2潮汐、潮流。结果表明，渤、黄、东海陆架的潮流有强弱之分以及往复流和旋转汉之别。在此基础上，计算了8种粒径沙的湖平均悬移输沙率、潮平均推移输沙以及相应的输沙率散度。根据输沙率散度的正负，划分了海底冲刷区与淤积区。根据不同粒径泥沙输沙率散度的相对大小，确定出海底的主要底质类型为砂质沉积、粉砂质泥沉积和以粉砂为主的混合沉积。计算结果表明，海底3种主要底负类型的分布格局与海底的冲淤格局以及与输沙率矢量的发散和聚合状况基本一致。在渤、黄、东海陆架，沙脊主要在强往复流区形成，沙席主要在强或较强的旋转流区形成，泥质沉积主要在弱潮流区形成。砂质沉积、泥质沉积以及混合沉积这3种主要底质类型并非孤立存在，而是受渤、黄、东海陆架潮流场控制而形成的一个完整的潮流沉积体系。渤、黄、东海陆架的砂质沉积与泥质沉积并非残留沉积，而是潮流沉积。在没有冷涡的情况下，黄、东海陆架的典型泥质沉积在弱潮流环境中同样可以形成，因此，认为冷涡并非黄、东海陆架典型泥质沉积形成的必要条件。 相似文献
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Measurement of the vertical distribution of total suspended matter (TSM) was carried out during summer throughout the Seto Inland Sea. TSM concentration near the bottom is influenced significantly by water movement and turbid bottom water is observed in all areas where median grain size (Md) of the bottom sediment is more than 47gf. The high concentration of TSM near the bottom may be due to resuspension of the surface layer of bottom sediments. Comparison of the organic content of the resuspended matter with that of the bottom sediment shows that the resuspended matter contains more organic matter with a lower C : N ratio than the bottom sediment. The C : N ratio of the resuspended matter is similar to that of TSM in the surface layer of the water column. It is thought that TSM in surface waters sinks and settles on the surface of the bottom sediment. This deposited material is then easily resuspended in the water column by tidal currents before becoming permanently incorporated into the bottom sediment. 相似文献
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对鄂霍次克海东南部科学院隆起区OS03-1岩心碎屑重矿物及火山灰层进行了详细分析。岩心重矿物以紫苏辉石、绿帘石和普通角闪石为主,特征矿物为钛磁铁矿和普通辉石,矿物特征表明本岩心的物质主要来源于冰筏搬运(陆源)和火山喷发。陆源物质大部分来源于鄂霍次克海西部和北部地区,少量来自堪察加半岛冰川携带沉积物;火山物质则来源于堪察加半岛和千岛群岛的火山喷发产物。在岩心中识别出3个火山灰层,各种证据表明火山灰层1与已知的K2火山灰层相同,形成年代为26ka BP;火山灰层3具有明显火山物质与陆源物质混合特征,而火山灰层2则只能通过碎屑矿物的含量特征来判定,外在颜色不明显,已经明显的被陆源物质所稀释。研究表明,碎屑矿物组分参数可以有效地指示物质来源,也是识别火山灰层存在(特别是被陆源物质稀释)的可靠指标。 相似文献
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台湾海峡表层沉积物的粒度和碎屑矿物分布特征方建勇 总被引：1，自引：0，他引：1
应用系统聚类分析和因子分析的方法对台湾海峡283个表层沉积物样品的粒度组成和85个样品的矿物组成进行了分析,结果表明:台湾海峡表层沉积物由6种沉积物类型组成,可以划分把它们为3种与沉积动力相对应的主要沉积环境区;在表层沉积物共发现碎屑矿物61种,以轻组分矿物为主,平均含量高达97.73%,共发现轻矿物14种;重组分矿物含量较低,平均为2.27%,共发现47种重矿物。影响台湾海峡表层沉积物矿物分布及含量变化的最重要因素是物质来源,其次是水动力条件以及矿物自身的变质程度等。台湾海峡表层沉积物的主要物质来源包括来自福建和台湾省河流的入海泥沙、海峡两岸的侵蚀和剥蚀物质、韩江及部分来自浙闽沿岸流携带的长江和钱塘江物质,台湾海峡晚更新世残留物及部分自生矿物等。 相似文献
10.
《Marine Chemistry》2002,79(2):81-97
Excitation–emission matrix (EEM) fluorescence spectroscopy was employed to study the chemical nature of organic matter readily released into solution from sediment particles during episodes of resuspension. Surface sediment samples collected from five locations within the Hudson River Estuary and the Inner New York Bight were resuspended in their respective bottom waters for periods ranging from 30 s to 2 h. In most cases, fluorescence characteristics of the sample after resuspension differed from those predicted by conservative mixing of bottom and pore waters. Examination of excitation–emission matrices revealed that resuspension resulted in: (1) more intense humic-like fluorescence (Ex/Em 310/420 nm), and (2) greater fluorescence in the longer wavelength region of the spectrum (Ex/Em 330–388/440–480 nm) relative to the predicted values. Trends in the positions of excitation–emission maxima reported in the literature strongly suggest that fluorophores emitting at longer wavelengths are associated with increasingly degraded and/or aged organic matter. Thus, the data imply that resuspension of estuarine and coastal marine surface sediments releases degraded and/or aged, mineral-bound organic matter from the sediment matrix to the surrounding bottom waters. 相似文献
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海洋雾状层的成因及其对海洋碳循环过程的影响 总被引：2，自引：0，他引：2
海洋雾状层既是陆源物质进入海底的输送通道,又是海洋水体中沉降颗粒及底部再悬浮颗粒物的停留场所。雾状层物质来源主要有陆源、生源以及海底表层沉积物的再悬浮,不同海区、不同层位的雾状层的物质来源有所差异;雾状层的成因具有复杂性,既有物理作用,又有生物及化学作用,大量研究表明,海底洋流、内波(潮)等物理作用是雾状层形成的主要控制因素。雾状层中碳的存在形态主要有颗粒有机碳(POC)、溶解有机碳(DOC)、胶体有机碳(COC)以及无机碳,雾状层与其上下海水之间、雾状层与海底表层沉积物之间不同形态碳在生物-化学-物理动力系统作用下不断发生物质交换与迁移,对海洋碳循环生物地球化学过程起重要的控制作用,是整个海洋碳循环的一个不可忽视的环节。 相似文献
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重矿物组合、含量变化和特征矿物的分布及变化规律是沿海泥沙来源和运移趋势判断的重要手段之一。通过对廉州湾南部海域海底表层沉积物的重矿物分析 ,发现该区重矿物分布以北海地角为界 ,其百分含量和特征矿物南北有别 ,可能分别代表不同的物质来源区。其中廉州湾北部南流江流域来沙是该区主要物源 ,运移趋势为自 NE向 SW;地角西南岸段、岭南侧海岸侵蚀及银滩来沙也为该区提供了部分物源 ,运移趋势为绕过冠头岭沿海岸向 N方向运移。由于缺乏北海陆域陆相地层重矿物含量等相关资料 ,暂未做物质来源区的具体判断 相似文献
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Rock magnetic properties of unconsolidated sediments from the Korea Deep Ocean Study area of the northeastern equatorial Pacific were analyzed to trace the time-dependent variations of sedimentary environments. For upper Pleistocene sediments, light-brown sediments predominate, whereas the lower sediments deposited in the late Pliocene are dark brown. Rock magnetic properties also clearly differ among the two distinct color environments. Values of anhysteretic remanent magnetization and low-field magnetic susceptibility are highly responsive to changes in the color of the sediment. For example, comparatively low values denote a dominance of coarse-grained magnetic minerals as observed in the lower dark-brown layers. With respect to the content of magnetic minerals, coarse magnetic grains are highly concentrated in the darker-colored sediment layers. However, both the magnetic mineral dependent parameter (S ratio) and results of the scanning electron microscope observation indicate that magnetic mineral changes did not occur along the core depth, which means that there was no apparent source change. Without distinctive source changes, the variations in the rock magnetic properties likely reflect a process by which the magnetic grains were primarily transported by enhanced wind and bottom currents and affected by diagenetic dissolution as a function of both the time from burial and the extremely low sedimentation rates after deposition. 相似文献
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Precise hydrogeochemical modeling of early diagenesis is a key in the reconstruction of sedimentary basin models. This determines the mineralogical evolution of the sediment and consequently the porosity of the rock. During early diagenesis also part of the initial organic matter is converted into biogenic gas: CH4 CO2, and H2S. These processes are part of complex reaction chains during sedimentation, and biogeochemical reactions leave different signals that can be observed today. In this work, we reproduce the early diagenetic processes as integrated signals over geological times in sediments of the Demerara Rise by applying chemical thermodynamics using the PHREEQC (version 2) computer code. The investigated sediments are characterized by the presence of black shales in 410–490 mbsf and by a diagenetic barite layer above in 300–350 mbsf at depth of sulfate-methane transition (SMT). We determine the parameters that influence the location of diagenetic barite peaks in sediments overlying black shales by means of a novel modeling approach. Crucial parameters are the amount of bacterial organic matter mineralization, sedimentation rates and bottom water sulfate concentrations. All parameters are intertwining and influence the sulfate-methane cycle. They affect the location of the SMT visualized by diagenetic barite peaks. However, our model approach opens a wide field in exploring early diagenetic reactions, processes and products (such as biogenic methane) over geological times mirrored by diagenetic minerals and pore water concentration profiles that can be detected in present-day sediments. 相似文献
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Masaharu Fukue Koji Uehara Yoshio Sato Catherine Mulligan 《Marine Georesources & Geotechnology》2013,31(3):222-233
The re-suspension method consists of (1) dispersion of the sediment by air-water jets, (2) pumping of the suspension (small particles and organic matter), (3) settlement in a tank, (4) filtration and (5) disposal of solids (followed by incineration in this case). The pilot test was performed to clean up an area of 3000 m2. The dispersed depth of the bottom was approximately 50 cm. The time spent for the work was two weeks. The amount of re-suspended solid removed from the bottom was about 8 tonnes in dry mass. Since the solids contain high concentrations of chemical oxygen demand (COD), total phosphorous (T-P), total nitrogen (T-N) and sulfides, the remaining sediment was considerably improved. Quantitative analyses showed that the full-scale implementation would enable the removal of about 10% of the re-suspended solids, and reduce COD by 95%, T-P by 50%, T-N by 100% and sulfide by 75% for re-deposited sediments in comparison to the original sediments. 相似文献
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Mineral provinces and material provenance of the surficial sediments near the Zhongsha Islands in the South China Sea 总被引：1，自引：0，他引：1
1 IntroductionThe South China Sea is one of the northwesternPacific marginal basins, which is located atthe junc-tion region among Euro-Asia plate, Pacific plate andIndia plate. Owing to its unique geological charac-teristics, the South China Sea has beco… 相似文献
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Concentrations of selected heavy metals (Cr, Cu, Ni, Pb and Zn) from surface sediments, suspended particulate matter and settling particles in the southern Barcelona continental margin were studied in order to evaluate the environmental impact of the anthropogenic metals discharged by the Llobregat River in this Mediterranean area. The temporal variation of heavy metals discharged by this river onto the continental shelf is clearly related to the river water flow. Part of the fine sediment and associated heavy metals transported by the Llobregat River during periods of low river flow accumulate on the river bed, and they are totally removed and discharged onto the Barcelona continental shelf during sporadic river water flow increases. Metals produce significant anomalies of chromium (×2.5), copper (×3.4) and zinc (×3.7) in the surface sediments of the Llobregat prodelta and tend to be transported along the continental shelf following the mean flow. Metals associated with the finest suspended flocs transferred to the slope are controlled by the shelf-slope density front and are transported along slope by the general geostrophic current, instead of accumulating and becoming concentrated in the slope bottom sediments. Settling particulate matter collected in sediment traps on the Barcelona continental slope offshore of the shelf-slope front shows low heavy metal concentrations except in a few sediment trap samples that are significantly metal-enriched in chromium (×4.5) and zinc (×6.8). This enrichment is associated with very short and sporadic river flow increases and is only recorded inside the Foix submarine canyon, which acts as a preferential conduit for the shelf-slope sediment transfer. 相似文献
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The characteristics and distribution patterns of detrital minerals (0.063~0.125 mm) in marine sediments provide a significant indicator for the identification of the origin of sediment.The detrital mineral composition of 219 surface sediment samples was analysed to identify the distribution of sediments within the western Philippine Sea. The area can be divided into three mineral provinces: (I) province east of the Philippine Trench, the detrital minerals in this province are mainly composed of calcareous or siliceous organisms, with the addition of volcanogenic minerals from an adjacent island arc; (II) middle mineral province, clastic minerals including feldspar, quartz and colorless volcanic glass, sourced from seamounts with intermediate-acid volcanic rock, or erupting intermediate-acid volcano; (III) province west of the Palau—Kyūshū Ridge, the matter provenance within this province is complex; the small quantity of feldspar and quartz may be sourced from seamounts or erupting volcano with intermediate-acid composition, with a component of volcanic scoria sourced from a volcano erupting on the Palau—Kyūshū Ridge. it is suggested that, (1) Biogenic debris of the study area is closely related to water depth, with the amount of biogenic debris controlled by carbonate lysocline. (2) Volcaniclastic matter derived from the adjacent island arc can be entrained by oceanic currents and transported towards the abyssal basin over a short distance. The weathering products of volcanic rocks of the submarine plateau (e.g.,Benham Plateau) and adjacent ridges provide an important source of detrital sedimentation, and the influence scope of them is constrained by the intensity of submarine weathering. (3) Terrigenous sediments from the continent of Asia and the adjacent Philippine island arc have little influence on the sedimentation of this study area, and the felsic mineral component is probably sourced from volcanic seamounts of intermediate-acid composition. 相似文献
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水文过程对河流悬移质化学组成的影响——以珠江流域为例 总被引：4，自引：0，他引：4
用等离子体原子发射光谱法（ICP-AES）分析了珠江马口站和三水站1997-1998年度3个典型水文时段径流悬移质中部分金属元素的含量，同时用元素分析仪测定了其中的有机碳、氮的含量，结果表明，在不同性质的水文动力条件下，流域侵蚀产出的河流悬移质的化学组成发生了变化，这主要缘于有机质在悬移质中所占质量分数的差别。汛期增强的水文动力主要表现为对流域土壤矿物的优先侵蚀，虽然有机质的总侵蚀量也同时增加，但在悬移质中的质量分数却相对减少，而在枯水期较弱的水文动力条件下，河流悬移质中有机质的质量分数增加，悬移质中的有机质对液相中的部分重金属元素产生较矿物更大的吸附作用。 相似文献