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1.
The observed relation between the vertical distribution of suspended matter and the size distribution of bottom sediment in
the Hiuchi-Nada area indicates that a turbid bottom water layer exists above the bottom when the bottom sediment is of silt
size. The turbid bottom water is thought to be produced by resuspension of bottom sediment.
Measurements of the temporal variation of resuspended matter and water movement near the bottom was carried out for one full
tidal cycle at an anchored station. The concentration of resuspended matter reached a maximum at the time of strongest ebb
and flood flow. 相似文献
2.
2005年7月在赤道东北太平洋的3个测站分层采集了悬浮体水样.利用ICP-MS对悬浮体的元素组成进行了测试,从测试的47种元素中筛选出了钡和铝分别作为悬浮体生源组分和陆源组分的示踪元素.悬浮体中钡含量为0.02~0.19μg/dm3,其中生源钡含量为0.01~0.13μg/dm3,铝含量为0.33~18.54μg/dm3.生源钡和铝元素含量及其比值在水体中的分布特征与悬浮体含量的相对应,分为三段.水体透光层生物作用和近底层底质沉积物再悬浮作用是其在水体表层和近底层显著变化的原因.近底雾状层内生源钡和铝元素含量的比值从水体向底质沉积物中降低,至底质沉积物降到最低,显示出底质沉积物再悬浮对悬浮体组分和含量的影响,可以作为近底雾状层颗粒物质运移的示踪指标. 相似文献
3.
Phosphorus dynamics in Tokyo Bay waters were investigated along with other oceanographic variables. Seasonal variations of dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) are inversely correlated with each other, and reflect variation in biological activity. A high concentration of PP in summer surface waters is caused by high primary production. The PP settled in the deeper layer is decomposed, and orthophosphate is regenerated within the water column and in sediments. Even during summer stratification period, the regenerated orthophosphate is occasionally advected upward by wind-induced water mixing and contributes to phytoplankton growth in the upper layer. Some dissolved organic phosphorus is producedin situ from PP, but it may be rapidly decomposed in the water column. The ratios of Cchlorophylla and CN in particulate matter suggest that phytoplankton in the summer surface waters of Tokyo Bay are limited neither by nitrogen nor by phosphorus. The PN ratio in particulate matter varies substantially but it is positively correlated with the ambient concentration of DIP. Phytoplankton take up and store phosphorus within their cells when ambient DIP exceeds their demand. An abundance of total phosphorus in the summer water column can be attributed to increased discharge of river waters, although enhanced release of orthophosphate from anoxic sediments cannot be discounted. 相似文献
4.
三峡截流后长江口秋季TSM、POC和PN的分布特征 总被引：2，自引：0，他引：2
基于2004年11—12月长江口56个站位的悬浮体调查资料,分析了长江口区悬浮体总量(TSM)、颗粒有机碳(POC)和颗粒氮(PN)质量浓度的平面分布特征,探讨该区TSM及颗粒有机质的物质来源和三峡截流对长江三角洲的影响。结果表明,表、底层TSM与POC、PN质量浓度之间存在显著的正线性相关关系并都呈现出南高北低的格局,说明了长江悬浮颗粒物入海后主要沿东南方向输运。POC、PN质量分数与POC、PN的质量浓度不同,它们与TSM质量浓度对数有负相关关系。由于河口区底质再悬浮作用显著,TSM和POC、PN质量浓度呈现表层低、底层高的特点。长江口悬浮体主要来自长江径流和底质沉积物的再悬浮。与三峡截流前数据的对比表明,截流对目前长江口区的TSM和POC尚未造成明显的影响。 相似文献
5.
冲绳海槽中南部及其邻近陆架悬浮体的分布、组成和影响因子分析 总被引：7，自引：3，他引：7
初夏冲绳海槽中南部海域悬浮体含量的分布特点为:表层水体中部海区高,南北海区低;中底层水体自南西至北东由低至高.从陆架到海槽断面的悬浮体含量分布为陆架最高值区、陆坡最低值区和海槽低值区.悬浮体组成包括矿物岩石碎屑、生物骨屑以及絮凝体.矿物岩石碎屑主要分布在陆架区中、下层水体,生物骨屑主要分布在海槽区(整个水层)和陆架区上层水体,絮凝体在研究区都有分布.海槽区与陆架区的悬浮体含量垂直分布和组分特征具有明显的差异.研究区悬浮体分布和组成主要受控于黑潮对陆架物质向冲绳海槽输送的阻隔、生物生产量以及地形、地理环境. 相似文献
6.
The aim of this study is to understand the various sources and factors controlling the abundance and distribution of the metals through the analyses of selected metals (iron, manganese, chromium, copper, zinc and cobalt), sand, silt, clay, organic carbon and magnetic susceptibility of the surface sediments of Zuari estuary in three different seasons. Total suspended matter (TSM) concentration and salinity of near surface and bottom waters were also measured. The study undertaken for three seasons, based on 18 selected stations all along the estuary, indicated that the concentration of most of the metals were comparatively higher during pre-monsoon than in monsoon and post-monsoon seasons. Further, along the length of the estuary, high concentrations were observed at lower middle and lower estuary and also at few stations at the upstream end. Salinity, distribution of TSM, size of the sediment, organic matter, geomorphological setup, fresh water input from land and release of industrial waste within the estuary played a role in distribution and concentration of metals. Magnetic measurements indicated the dominance of haematite like minerals and helped in understanding the source and depositional processes. 相似文献
7.
底边界层水沙观测系统和应用 总被引：2，自引：0，他引：2
利用现代先进的光学和声学测量仪器(ADP、PC-ADP、ADV、OBS等),组制四角架观测系统用于底边界层的水沙观测.此观测系统既可获取垂向流速场,更可获取常规水文观测难以获取的高分辨率的近底流速、近底单点紊动过程、近底温盐沙和波浪过程.利用此观测系统于2007年8月在长江口北槽最大浑浊带内进行了实地观测.分析四角架观测数据与同步船测底部数据表明,四角架观测系统在近底(特别是底部明显分层)观测时表现出明显优势.常规水文观测测得底部含沙量一般只相当于距底70～120 cm高度含沙量;船测底部最大含沙量为5.8 kg/m 3,而架测距底30 cm处最大含沙量有25 kg/m 3;近底含沙量较高时往往出现强分层,强分层时实测距底30 cm处含沙量可达距底120 cm处含沙量的5倍;船测底部流速比架测距底30 cm处流速平均偏大45%;但距底30 cm处最大流速仍可达1.2 m/s.船测数据也验证了四角架观测数据的正确性. 相似文献
8.
The temporal and spatial distribution of total and organic particulate matter is investigated in the Bideford River estuary. Particulate matter is homogenously distributed in both the water column and the surface sediment, due to high rates of resuspension and lateral transport. The measured mean sedimentation rate for the estuary is 183·5 g of particulate matter m?2 day?1, of which more than half is due to resuspension.The surface sediment of the estuary is quantitatively the dominant reservoir of organic matter, with an average of 902·5 g of particulate organic carbon (POC) m?2 and 119·5 g of particulate organic nitrogen (PON) m?2. Per unit surface area, the sediment contains 450 times more POC and 400 times more PON than the water column. Terrestrial erosion contributes high levels of particulate matter, both organic and inorganic, to the estuary from the surrounding watershed. Low rates of sediment export from the estuary result in the accumulation of the terrigenous material. The allochthonous input of terrigenous organic matter masks any relationship between the indigenous plant biomass and the organic matter.In the water column, a direct correlation exists between the organic matter, i.e. POC and PON, concentration and the phytoplankton biomass as measured by the plant pigments. Resuspension is responsible for the residual organic matter in the water column unaccounted for by the phytoplankton biomass.The particulate content of the water column and the surface sediment of the estuary is compared to that of the adjacent bay. Water-borne particulate matter is exported from the estuary to the bay, so that no significant differences in concentration are noted. The estuarine sediment, however, is five to six times richer in organic and silt-clay content than the bay sediment. Since sediment flux out of the estuary is restricted, the allochthonous contribution of terrigenous particulate matter to the bay sediment is minor, and the organic content of the bay sediment is directly correlated to the autochthonous plant biomass. 相似文献
9.
J. White 《Marine Geophysical Researches》1990,12(1-2):145-152
A sediment trap is a container deployed in the water column with the aim of providing a representative sample of the material settling through that water column before it passes to a greater depth and ultimately to the seabed or lake bottom. A review of the previous literature shows cylinders and baffled funnels to be the most efficient sediment trap design in flows less than 0.1 m/s. For flow velocities above 0.1 m/s recent evidence suggests upwelling from the trap base, and possible undercollection. The degree of undercollection depends on the flow velocity, the type of trap, the height: diameter (aspect) ratio of the trap, and the type of sediment. Recent experiments suggest that cylinders with an aspect ratio of 3 may be efficient collectors in velocities up to 0.2 m/s. The use of cylinders is not recommended in velocities above 0.2 m/s. For unbaffled asymmetric funnels a lower limit of 0.12 m/s is suggested. 相似文献
10.
Extracellular enzyme activities were compared among surface water, bottom water, and sediments of the Delaware Estuary using six fluorescently labeled, structurally distinct polysaccharides to determine the effects of suspended sediment transport on water column hydrolytic activities. Potential hydrolysis rates in surface waters were also measured for the nearby shelf. Samples were taken in December 2006, 6 months after a major flood event in the Delaware Basin that was followed by high freshwater run-off throughout the fall of 2006. All substrates were hydrolyzed in sediments and in the water column, including two (pullulan and fucoidan) that previously were not hydrolyzed in surface waters of the Delaware estuary. At the time of sampling, total particulate matter (TPM) in surface waters at the lower bay, bay mouth, and shelf ranged between 31 mg l−1 and 48 mg l−1 and were 2 to 20 times higher than previously reported. The presence of easily resuspended sediments at the lower bay and bay mouth indicated enhanced suspended sediment transport in the estuary prior to our sampling. Bottom water hydrolysis rates at the two sites affected by sediment resuspension were generally higher than those in surface waters from the same site. Most notably, fucoidan and pullulan hydrolysis rates in bay mouth bottom waters were 22.6 and 6.2 nM monomer h−1, respectively, and thus three and five times higher than surface water rates. Our data suggest that enhanced mixing processes between the sediment and the overlying water broadened the spectrum of water column hydrolases activity, improving the efficiency of enzymatic degradation of high molecular weight organic matter in the water with consequences for organic matter cycling in the Delaware estuary. 相似文献
11.
Sediment and water column data from four sites in North, Central and South San Francisco Bays were collected monthly from November 1999 through November 2001 to investigate the seasonal variation of benthic organic matter and chlorophyll in channel sediments, the composition and quality of sediment organic matter (SOM), and the relationship between seasonal patterns in benthic organic matter and patterns in water column chlorophyll. Water column chlorophyll peaked in the spring of 2000 and 2001, characteristic of other studies of San Francisco Bay phytoplankton dynamics, however an unusual chlorophyll peak occurred in fall 2000. Cross-correlation analysis revealed that water column chlorophyll at these four channel sites lead sediment parameters by an average of 2 to 3 months. Sediment organic matter levels in the San Francisco Bay channel showed seasonal cycles that followed patterns of water column production: peaks in water column chlorophyll were followed by later peaks in sediment chlorophyll and organic matter. Cyclical, seasonal variations also occurred in sediment organic matter parameters with sediment total organic carbon (TOC) and total nitrogen (TN) being highest in spring and lowest in winter, and sediment amino acids being highest in spring and summer and lowest in winter. Sediment chlorophyll, total organic carbon, and nitrogen were generally positively correlated with each other. Sediment organic matter levels were lowest in North Bay, intermediate in Central Bay, and highest in South Bay. C:N ratio and the ratio of enzyme hydrolyzable amino acids to TOC (EHAA:TOC) data suggest that SOM quality is more labile in Central and northern South Bay, and more refractory in North Bay and southern South Bay. 相似文献
12.
Material transport through the shelf edge to the deep ocean determines the fate of particulate matter generated in productive coastal seas. In stratified estuaries, onshore flow in the bottom layer generally keeps particulate matter generated in the upper layer and settled down to the bottom layer within the estuaries. AT the shelf edge of Tokyo Bay under the condition of average onshore flow in the bottom layer, we observed higher vertical sediment flux during ebb than flood tidal currents. The on-shelf and off-shelf differences in turbulent mixing and water depth mainly cause such difference in sediment flux. We propose to call this export process of particulate matter the tidal pump at the shelf edge. 相似文献
13.
Al-Zibdah Mohammad Oqaily Firas Al-Najjar Tariq Manasrah Riyad 《Ocean Science Journal》2008,43(1):9-16
Environmental qualities of coastal water and bottom sediment were assessed at Jordan's northernmost tip of Gulf of Aqaba to
evaluate possible impacts of the bordering fish pen cages in Eilat. Results showed significant differences between surface
and bottom water in the chemical and physical variables in the different months of the year (2004-2005). Chlorophyll a was
also significantly higher in bottom water when compared to that of the offshore water. Nitrate and ammonia were significantly
higher in bottom water than the surface water at each individual station. The upper 2 cm of sediment sample recorded higher
values of total phosphorus and organic matter. Seasonality affected the content of total phosphorus, organic matter, redox
potential and color especially at the sediment layer below 3 cm of the sediment core. The present investigation showed slight
modification of water and sediment qualities but no clear sign of eutrophication was observed. However, to maintain sustainability
of healthy environmental conditions at the northern tip of Gulf of Aqaba potentials of any possible environmental risks arising
from the fish farms or any other coastal investment should be carefully considered. 相似文献
14.
Isao Kudo Takeshi Yoshimura Choon-Weng Lee Mitsuru Yanada Yoshiaki Maita 《Journal of Oceanography》2007,63(5):791-801
Nutrient regeneration and oxygen consumption after a spring bloom in Funka Bay were studied on monthly survey cruises from
February to November 1998 and from March to December 1999. A high concentration of ammonium (more than 4 μmol l−1) was observed near the bottom (80–90 m) after April. Phosphate and silicate gradually accumulated and dissolved oxygen decreased
in the same layer. Salinity near the bottom did not change until summer, leading to the presumption that the system in this
layer is semi-closed, so regenerated nutrients were preserved until September. Nitrification due to the oxidation of ammonium
to nitrate was observed after June. Nitrite, an intermediate product, was detected at 4–7 μmol L−1 in June and July 1999. Assuming that decomposition is a first order reaction, the rate constant for decomposition of organic
nitrogen was determined to be 0.014 and 0.008 d−1 in 1998 and 1999, respectively. The ammonium oxidation rate increased rapidly when the ambient ammonium concentration exceeded
5 μmol L−1. We also performed a budget calculation for the regeneration process. The total amount of N regenerated in the whole water
column was 287.4 mmol N m−2 in 4 months, which is equal to 22.8 gC m−2, assuming the Redfield C to N ratio. This is 34% of the primary production during the spring bloom and is comparable to the
export production of 25 gC m−2 measured by a sediment trap at 60 m (Miyake et al., 1998). 相似文献
15.
The population dynamics of attached bacteria at the water-sediment interface were studied in a mesotrophic swampy bog, Matsumi-ike,
near Tsukuba, Japan. The density of attached bacteria was higher at the sediment boundary layer than in the water column,
and low inside the sediment (deeper, than 10 mm below the sediment surface) throughout the year. The density of bacteria attached
on the glass slide was highest during spring when the source of organic matter in the water column was mainly withered cattail,
and gradually decreased toward summer, while the phytoplankton became the dominant source of organic matter in the water column.
The epibacterial populations in the water column and at the boundary showed almost the same seasonal fluctuation in attachment
and detachment rates. However, bacterial growth rates did not show the same seasonal fluctuation, and annual average growth
rates on the glass slides were all lower than that of bacterioplankton (free-living bacteria in water) in the water column. 相似文献
16.
利用2011年春季(5-6月)、2009年夏季(8月)、2010年秋季(11-12月)和2009 年冬季(12月一次年1月)4个航次实测的悬浮体质量浓度资料,分析了东海陆架表层水体总悬浮体、有机悬浮体和无机悬浮体质量浓度的季节分布特征。结果表明,东海陆架表层水体总悬浮体质量浓度冬半年高于夏半年,等值线基本平行于岸线,在浙江沿岸29°N附近有一浑水舌向东南方向延伸,常年存在2个高值中心和2个次高值中心。有机悬浮体质量浓度则为夏半年高于冬半年,存在2个高值中心和2个次高值中心,季节变化显著。无机悬浮体质量浓度分布趋势相似于总悬浮体质量浓度,但整体轮廓线向近岸收缩约0.5°,常年存在2个高值中心和1个次高值中心。有机悬浮体占总悬浮体百分比按季节从高到低依次为春季、夏季、冬季和秋季,其中长江口、杭州湾外近海海域和黑潮区为东海有机悬浮体百分含量高值区。 相似文献
17.
A time-series sediment trap was deployed from December 1994 to February 2002 at the mouth of Tokyo Bay (35°03′ N, 139°40′
E; water depth, 850 m). Sinking particles were obtained with a time interval of one week at a depth of approximately 100 m
above the sea floor. Observed total mass fluxes varied from 3.3 to 226.7 g/m2/day with an average of 28.0 g/m2/day. Concentrations of rare earth elements, Al, Ca and Si in particulate materials were measured. The combustible fraction
at 450°C is assumed to be equivalent to the organic matter content. Contents of biogenic materials, namely organic matter,
opal and calcium carbonate, were about 30% and the content of lithogenic material was about 70%. Using La/Yb ratios of particles
from the sediment trap and Tama-gawa River and surface sediment of Tokyo Bay, it was estimated that about 50% of the lithogenic
particles collected in the sediment trap at the mouth of Tokyo Bay originated from resuspended surface sediment in Tokyo Bay.
An increasing trend of Opal/CaCO3 ratio in the sinking particles was found in the spring season. It is suggested that the relative increase of diatoms is due
to the decreasing dissolved inorganic nitrogen input into Tokyo Bay. 相似文献
18.
The beam attenuation coefficient, organic carbon (POC) and organic nitrogen (PON) contents of suspended materials in Etauchi
Bay, which has little inflow of river water as well as very weak tidal current (maximum speed: 6.5cm·sec−1), were measured as a function of depth for all seasons to understand a seasonal variation of bottom turbidity layer. In spring
and summer, the beam attenuation coefficient in bottom layer and POC and PON contents of suspended materials in the surface
water layer increased with time, which brought the occurrence of the bottom turbidity layer. From autumn to winter, however,
their concentrations became low and constant over the whole depth almost independent of time. As a result, the bottom turbidity
layer disappeared in winter and beam attenuation coefficient became constant over the whole depth. From these results, it
may be considered that the bottom turbidity layer was produced by phytodetritus brought from surface water layer, rather than
by resuspension of bottom sediment in Etauchi Bay. 相似文献
19.
Giorgio Bavestrello Riccardo Cattaneo-Vietti Roberto Danovaro Mauro Fabiano 《Marine Ecology》1991,12(4):281-292
Abstract. The detritus rolling down a vertical cliff was studied at Portofino Promontory (Ligurian Sea, Italy) at 16 m depth (January 1988- January 1989). The large amount of collected sediment is mainly due to the position of the traps; they collected not only the sedimenting material, but also the detritus rolling down along the cliff. The amount of sediment matter is 7 times greater in winter than in summer, showing a good correlation with rough seas and rain that cause a "mechanical cleaning" of animal and plant debris (Sérpulid tubes, shells, exuvias. leaves) along the cliff.
The Total Suspended Matter (TSM) in the water column shows maximum values in March and September. The organic fraction has an average concentration of 0.81 mg 1-l . The phytoplanktonic biomass, measured as Chi a , shows an annual cycle with a peak in spring (1–2.7μg·l-1 ). while in other periods of the year the value is about 0.3-0.5 μg·1-1 . A significant relationship was found between organic detritus in the collected sédiments and the Chi a in the water column. The great influence of the rocky wall detritus on the normal trend of the TSM in the coastal water column is pointed out. 相似文献
The Total Suspended Matter (TSM) in the water column shows maximum values in March and September. The organic fraction has an average concentration of 0.81 mg 1
20.
Distribution of the anoxic water mass in the eastern part of Hiuchi-Nada was investigated from 1981 to 1983. A cold water mass was found on the bottom of the area concerned in summer, and a second (i.e. lower) thermocline appeared just above the cold water mass. The anoxic water was observed below a second thermocline. The horizontal distribution of the cold water mass coincided with that of the anoxic water mass, and also with a region of high concentration of organic matter in the sediment. These results suggest two important effects of the second thermocline on the generation of the anoxic water mass. Firstly, it prevents supply of dissolved oxygen from the upper to bottom layer of the water column. Secondly, it accelerates settling of particulate material resulting in a large accumulation of organic matter in the bottom water and the sediment which leads to an increase in the rate of oxygen consumption. The net oxygen consumption rate in the bottom layer in this sea was much smaller than that in Mikawa Bay where anoxia occurs at almost the same level as in Hiuchi-Nada. This finding also suggests the important role of the second thermocline. 相似文献