共查询到20条相似文献，搜索用时 15 毫秒
1.
B.R. Stanton 《Estuarine, Coastal and Shelf Science》1984,19(1):89-104
Four New Zealand fjords were surveyed in March and April 1980. In Milford Sound, unusually low dissolved oxygen levels in Stirling Basin suggests that intermittent stagnation events occur, while in Deep Water Basin the bottom water was virtually anoxic. Near the entrance to Milford Sound aperiodic currents up to 38 cm s?1 were recorded. In Isthmus Sound and Long Sound, in Preservation Inlet, contrasting circulation and mixing regimes were found and tidal currents up to 60 cm s?1 over the entrance sill to Long Sound are important for deep water renewal. 相似文献
2.
Shizuko Hirata 《Journal of Oceanography》1983,39(5):211-219
By combined use of chloroform extraction and Amberlite XAD-2 resin chromatography, metal-organic compounds dissolved in coastal seawaters of Harima Sound, the Seto Inland Sea, were separated into three groups: hydrophobic, hydrophilic neutral and basic, and hydrophilic acidic. The hydrophobic metal-organic compounds, which are associated with organic matter with molecular weight less than 300, accounted for only a small fraction of the metal-organic compounds; 6 % for Cu and an insignificant fraction for Fe, Mn and Zn. The hydrophilic metal-organic compounds with molecular weights between 100 and 1,500 were major components of the metal-organic compounds. The metals associated with the organic matter on average accounted for 12 % of the Fe, 11 % of the Mn, 7 % of the Zn and 23 % of the Cu of the reactive dissolved metals. 相似文献
3.
Teruhisa Komatsu 《Journal of Oceanography》1989,45(2):106-115
This paper examines the influence of aSargassum forest on distributions of illuminance, dissolved oxygen content and pH in a small cove facing Wakasa Bay. Spatial distributions of illuminance, dissolved oxygen content, water density and pH were observed for June 1982 during the season of luxuriant seaweed growth, and for August 1982 during the season of little growth. Observations of dissolved oxygen content, water density and pH were made during the day and at night. The values of illuminance at the sea surface were decreased to less than 40% inside theSargassum forest when the sun was highest in the sky during the season of luxuriant growth. Density stratification occurred during every observation. Dissolved oxygen content and pH showed similar patterns of spatial distribution. Their horizontal distributions reversed from day to night, and consisted of two types: (1) higher values inshore and lower values offshore in the upper layer during the day with (2) lower values inshore and higher values offshore at night. Distributions of illuminance about noon, and dissolved oxygen content and pH at night showed patterns corresponding to the vertical distribution of algal density of theSargassum forest. Dissolved oxygen was supersaturated at every observation point during the daytime, but at night it was undersaturated in the lower part of the forest or along the bottom in June and August, respectively. Processes that brought about these spatial distributions are discussed. 相似文献
4.
Both water and suspended particulate matter in the deep water of the Gulf of St. Lawrence are greatly enriched in manganese. Maximum dissolved manganese concentrations are encountered close to the sediment-water interface whereas the particulate matter with highest manganese content occurs 30–100 m above the bottom. The elevated concentrations are attributed to the diagenetic release of dissolved manganese from the underlying fine-grained sediments and its subsequent precipitation in the water column. The rate of manganese precipitation is rapid compared to the rates of diffusion and mixing in the bottom water. Part of the manganese-enriched particulate matter becomes mixed throughout the water column by advection and diffusion. Thus, particles enriched in manganese can ultimately be carried into the open ocean by prevailing currents. This process, which appears to be widespread in eastern Canadian coastal waters, enables manganese originally associated with rapidly settling terrigenous particles to be transferred to slowly settling fine-grained suspended particles entering the ocean from coastal environments. In this way, riverborne manganese of terrigenous origin may well account for a major proportion of the excess manganese in pelagic sediments. 相似文献
5.
南沙群岛海域表层沉积物中有机物、铁和锰的分布特征 总被引：1，自引：0，他引：1
通过1997年11月（冬季）和1999年7月（夏季）两个航次对南沙群岛海域的现场调查，实测了南沙深海盆表层沉积物中的有机物，Fe和Mn的含量，讨论了沉积物中Fe、Mn的平面和深度分布。在沉积物的上层几厘米处Fe和Mn都出现了峰值，这是上层Mn^2 （Fe^2 ）氧化，再沉淀引起的，沉积物中Fe和Mn的深度分布是氧化锰（铁）和氢氧化锰（铁）的还原，扩散和再沉淀的结果，细菌在海洋环境的Fe、Mn循环中起着重要的作用，在大洋底的厌氧环境中细菌将Fe、Mn还原为低价离子或可溶性化合物向间隙水和上覆水移动，在沉积物表层的氧化条件下细菌又使环境中的Fe、Mn沉淀，使其再次富集。 相似文献
6.
Dissolved and total dissolvable manganese concentrations have been measured at four stations in the western North Atlantic Ocean. Total dissolvable manganese concentrations are high in surface waters, decrease to uniformly low levels throughout the bulk of the water column, and increase in the bottom nepheloid layer. Dissolved Mn (Mnd) concentrations follow the total dissolvable concentrations throughout the surface and deep waters but do not increase in the near-bottom waters.Deep water concentrations of Mnd decrease from 30 ng l?1 in the Newfoundland Basin to 20 ng l?1 in the Sargasso Sea. This change and other features of the deep water distribution of dissolved manganese could be associated with the slow oxidation of Mn2+ to MnO2. There is also evidence at one station of scavenging of manganese from the dissolved phase in the near-bottom layer which may again be related to the kinetics of manganese oxidation. 相似文献
7.
基于2020年夏季的大面航次观测数据,分析了烟台—威海北部海洋牧场及邻近海域海水溶解氧浓度垂向分布最小值（氧最小值层）的空间分布特征,并探讨了影响因素。从6月至8月,海水溶解氧浓度不断减小,垂向结构亦存在显著变化。海水溶解氧浓度垂向分布的最小值主要集中于7月的近岸海域,最小值大致从外海向近岸方向减小,其距离海底高度及与底层溶解氧浓度之差的绝对值均于双岛湾邻近海域为最大。海水溶解氧浓度垂向分布的最小值位于最强密度层结以下。但是海水溶解氧浓度垂向分布最小值的强度向北减小,而密度层结向北增大,两者的空间分布基本相反,说明密度层结抑制垂向湍流扩散可极大减少深层海水溶解氧的来源,是海水溶解氧浓度垂向分布最小值形成的必要条件,但不是主导因素。在海水溶解氧浓度垂向分布的最小值层,表观耗氧量存在垂向分布的最大值,大部分站点的pH存在垂向分布的最小值,说明局地增强、持续的生物地球化学耗氧是控制海水溶解氧浓度垂向分布最小值形成和空间分布的一个重要过程。研究结果表明氧最小值层是夏季烟台—威海北部近岸海水溶解氧垂向结构的典型特征之一。 相似文献
8.
ZhouWcihua WuYunhua ChenShaoyong YinKedong 《海洋通报(英文版)》2003,5(2):14-21
Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured, Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O2 and the upward flux of Mn^2 ( or Fe^2 ). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn^2 ( or Fe^2 ) in dissolved state to Mn^4 ( or Fe^3 ) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions. 相似文献
9.
A simple colorimetric method was developed for determining molybdenum in seawater by solvent extraction of its dithiolate and was then applied during a nine month study of Saanich Inlet. This inlet is a fjord on the coast of Vancouver Island, British Columbia, in which the bottom waters alternate between a weakly oxygenated and anoxic state. Results are given for the concentrations of dissolved and suspended molybdenum, suspended manganese, dissolved oxygen and of salinity measurements. Salinity-molybdenum correlations demonstrate that the deep waters are deficient in molybdenum, a conclusion consistent with reports that the sediments deposited in the reducing zone are enriched with molybdenum precipitated from the anoxic bottom waters. Suspended manganese, which occurs in large amounts as a result of the oxidative precipitation of dissolved Mn(II) diffusing from anoxic waters, has a distribution that is directly correlated to that of suspended molybdenum and which tends to be inversely related to that of dissolved molybdenum, suggesting that molybdenum is being coprecipitated with manganese oxides. Such a hypothesis is supported by the fact that the average molybdenum to manganese weight ratio of suspended matter closely approximates that of local manganese nodules, and by a mathematical analysis of the distribution data which includes development of a model for scavenging. Computations using the model relationships indicate that manganese oxide scavenging tends to concentrate molybdenum in the reducing waters where the anoxic processes responsible for its deposition in the sediments become operative. Additional calculations based upon current estimates of oceanic residence times suggest that manganese-oxide scavenging operating on an oceanic scale could be removing approximately 10% of the molybdenum being added to the oceans. 相似文献
10.
Hirokazu Ozaki Hajime Obata Mikio Naganobu Toshitaka Gamo 《Journal of Oceanography》2009,65(2):235-244
We measured potential temperature, salinity, and dissolved oxygen profiles from the surface to the bottom at two locations
in the north Ross Sea (65.2°S, 174.2°E and 67.2°S, 172.7°W) in December 2004. Comparison of our data with previous results
from the same region reveals an increase in potential temperature and decreases in salinity and dissolved oxygen concentration
in the bottom layer (deeper than 3000 m) over the past four decades. The changes were significantly different from the analytical
precisions. Detailed investigation of the temperature, salinity, dissolved oxygen and σ
3 value distributions and the bottom water flow in the north Ross Sea suggests a long-term change in water mass mixing balance.
That is to say, it is speculated that the influence of cool, saline, high-oxygen bottom water (high-salinity Ross Sea Bottom
Water) formed in the southwestern Ross Sea has possibly been decreased, while the influences of relatively warmer and fresher
bottom water (low-salinity Ross Sea Bottom Water) and the Adélie Land Bottom Water coming from the Australia-Antarctic Basin
have increased. The possible impact of global warming on ocean circulation needs much more investigation. 相似文献
11.
依据2017年8—9月对黄海海域溶解有机物(DOM)的调查，探讨了夏季黄海海水中溶解有机碳(DOC)和有色溶解有机物(CDOM)的空间分布特征。在表层海水中，受陆源影响较大的近岸海域CDOM含量相对较高，北黄海冷水团区域由于水产养殖的饵料引起DOC浓度升高，且该部分DOC以无色为主。DOC浓度随深度逐渐降低，而CDOM逐渐升高，该特征在冷水团区域更为显著，因此DOC和CDOM在冷水团区域的表底差异远大于浅水区的非冷水团区域。陆源输入和初级生产是引起表层DOC升高的主要原因，而光漂白则引起CDOM降低，同时光漂白还导致表层水体中CDOM分子量和芳香性低于底层。底层溶解氧饱和度在冷水团为80%～93%，均表现为弱不饱和状态。层化不仅阻碍了O2向底层水体输送，还抑制了DOC和CDOM的垂向混合，这是引起冷水团区域表底层DOC和CDOM差异较大的主要原因。 相似文献
12.
长江口邻近海域溶解态铝的分布及季节变化 总被引：2，自引：0，他引：2
基于2006年6、8、10月对长江口邻近海域的大面调查资料,分析了溶解态Al的分布及季节变化,讨论了水团混合、悬浮颗粒物及浮游植物水华对溶解态铝分布的影响。结果表明,3个航次溶解态铝的水平分布规律相似,都是近岸浓度最高,随着离岸距离的增加浓度降低,6、8、10月溶解态Al的平均浓度分别为(119±77)、(109±80)和(138±73)nmol/L,统计结果表明该海域的溶解态铝具有明显的季节变化。影响溶解态铝分布的主要因素有水团混合、底沉积物的再悬浮以及浮游植物的调节作用。 相似文献
13.
Dissolved trace element (copper, nickel, cadmium, zinc, cobalt, and iron) concentrations were measured in surface water samples collected from 27 stations in the San Francisco Bay and Sacramento—San Joaquin Delta during April, August and December of 1989. The trace element distributions were relatively similar for all three sampling periods, and evidenced two distinct biogeochemical regimes within the estuarine system. The two regimes were comprised of relatively typical trace element gradients in the northern reach and anthropogenically perturbed gradients in the southern reach of the estuary. These dichotomous trace element distributions were consistent with previous reports on the distributions of nutrients and some other constituents within the estuary.In the northern reach, trace element and dissolved phosphate concentrations were non-conservative. Simple estuarine mixing models indicated substantial internal sources of dissolved copper (46–150%), nickel (250–500%) and cadmium (630–780%) relative to riverine inputs in April and August, and sizable internal sinks for dissolved cobalt (> 99%) and iron (> 70%) during the same periods. Dissolved zinc fluxes varied temporally, with a relatively large (135%) internal source in April and a relatively small (29%) internal sink in August.Concentrations of many trace elements (copper, nickel, cadmium, zinc, and cobalt) in the southern reach were anomalously high relative to concentrations at comparable salinities in the northern reach. Mass balance calculations indicated that those excesses were primarily due to anthropogenic inputs (waste-water discharges and urban runoff) and diagenetic remobilization from benthic sediments. The magnitude of these excesses was amplified by the long hydraulic residence time of dissolved constituents within the South Bay.The influence of other factors was evident throughout the system. Notably, upwelling appeared to elevate substantially dissolved cadmium concentrations at the mouth of the estuary and authigenic flocculation appeared to dominate the cycling of dissolved iron in both the northern and southern reaches of the system. Biological scavenging, geochemical scavenging and diagenic remobilization were also found to be important in different parts of the estuary. Additional complementary information is required to quantify accurately these processes. 相似文献
14.
《Estuarine, Coastal and Shelf Science》2007,72(3):406-419
Vertical distributions of dissolved species across the sediment–water interface (SWI), including major cations (sodium, potassium, magnesium, calcium), minor cations (lithium, strontium, barium), redox sensitive species (dissolved manganese, iron, sulfate, sulfide, ammonium) and other chemical parameters (pH, alkalinity, soluble reactive phosphorous, dissolved silica) were studied in a Mediterranean lagoon used for intensive shellfish farming. In order to quantify the impact of this activity on diagenetic processes and the influence of seasonal changes, two stations contrasted with respect to organic carbon fluxes were sampled in Thau lagoon from March 2001 to August 2002 during four field campaigns in winter, spring, summer and fall. Well-defined layers enriched with redox sensitive species were observed following the conventional sequence of early diagenetic reactions. However, differences were observed between both stations in depths and thickness layers. Concentration gradients extended down to more than 92 cm depth at the central position of the lagoon (station C4 – 8 m depth) and down to 40 cm depth inside shellfish farming zones (station C5 – 9 m depth). Station C4 showed an unusual diagenetic signature: sharp dissolved oxygen, iron, nitrate and manganese gradients existed at the SWI but gradients of dissolved sulfide and alkalinity as well as other parameters (dissolved silica, Ba, etc.) were recorded only from 25 to 30 cm depth downward. Seasonal changes were observed in pore water composition as deep as 30–50 cm in station C4 (only 15 cm in station C5). The center of the lagoon is not directly subjected to biodeposits deriving from shellfish activity. Isotopic and bioturbation data allowed to rule out a reworking of the sediment deeper than a few centimeters. In addition to organic content of the sediment, physical parameters were likely to induce the 10–20 cm gap between dissolved iron and sulfide profile as well as the higher vertical extent of diagenetic sequence observed at station C4. Conversely to station C5, station C4 underwent stronger currents and wave effect probably generating advective transport of water through the sediment, but no permeability data were available to confirm this hypothesis. During summer, climatic conditions generated vertical stratification of the water column and transient suboxic conditions at the bottom. Such conditions drove the upward shift of redox fronts, compacting the diagenetic sequence. These effects were reinforced at station C5 by shellfish and its farm structures (mainly attenuation of current and increased heat absorption). 相似文献
15.
Svetlana V. Pakhomova Per O.J. Hall Mikhail Yu. Kononets Alexander G. Rozanov Anders Tengberg Andrei V. Vershinin 《Marine Chemistry》2007
Fluxes of dissolved forms of iron and manganese across the sediment–water interface were studied in situ in the Gulf of Finland and the Vistula Lagoon (Baltic Sea), and in the Golubaya Bay (Black Sea) from 2001 to 2005. Fluxes were measured using chamber incubations, and sediment cores were collected and sliced to assess the porewater and solid phase metal distribution at different depths. Measured and calculated benthic fluxes of manganese and iron were directed out of sediment for all sites and were found to vary between 70–4450 and 5–1000 µmole m− 2 day− 1 for manganese and iron, respectively. The behavior of the studied metals at various redox conditions in the near-bottom water and in the sediment was the main focus in this study. Our results show the importance of bottom water redox conditions for iron fluxes. We measured no fluxes at oxic conditions, intermediate fluxes at anoxic conditions (up to 200 μmole m− 2 day− 1) and high fluxes at suboxic conditions (up to 1000 μmole m− 2 day− 1). Total dissolved iron fluxes were generally dominated by iron(II). Contribution of iron(III) to the total iron flux did not exceed 20%. Obtained fluxes of manganese at all studied regions showed a linear correlation (r2 = 0.97) to its concentration in the porewater of the top sediment layer (0–5 mm) and did not depend on dissolved oxygen concentrations of bottom water. Organically complexed iron and manganese were in most cases not involved in the benthic exchange processes. 相似文献
16.
The horizontal and vertical distributions of manganese in sea water, interstitial water and sediments in the Hiro Bay, Seto Inland Sea, Japan, have been investigated. The outflow from a pulp mill is the primary source of manganese in this bay. The industrial waste water contained 0.19 mg l–1 of manganese, mostly in a dissolved form. This manganese diffused out both horizontally and vertically into the surrounding sea water. The content of manganese in the liquid and solid phases in the sediments, however, are inverse with that in the sea water; namely the lowest concentration of manganese in the sediments was observed at the station near the outfall and manganese concentration increased with the distance from the outfall. 相似文献
17.
溶解氧(DO)是海洋生物生存不可缺少的要素。随着人类活动的增加，全球近岸海域低氧情况愈发严重，已经成为威胁海洋生态系统健康的重要因素。通过对2017年5?9月秦皇岛外海区域的观测调查，探讨了该海域低氧与酸化的形成机制并计算了月平均耗氧速率。结果表明，5月秦皇岛外海水体混合较为均匀，表、底层DO浓度一致，均大于8 mg/L；6月开始形成密度跃层，与此同时底层DO浓度和pH开始下降；8月底层呈现明显的低氧和酸化状态，DO浓度下降至2～3 mg/L，pH下降至7.8以下；9月随着层化消失，底层水体DO浓度和pH逐渐升高。相关性分析显示，DO和叶绿素a (Chl a)以及pH具有良好的耦合性，说明秦皇岛外海区域的低氧发生过程主要为局地变化。同时表明DO浓度和pH主要受水体中浮游植物的光合作用和有机物有氧分解的影响。通过箱式模型计算得到2017年6?8月密度跃层以下水体及沉积物耗氧速率为951～1193 mg/(m2·d)[平均为975 mg/(m2·d)]。综合来看，水体分层是秦皇岛外海低氧和酸化发生的先决条件，跃层以下的有机物分解耗氧则是底层水体发生低氧和酸化的重要原因。 相似文献
18.
《Marine Chemistry》2001,73(1):21-36
As part of the ANTARES 3/F-JGOFS cruise, the distributions of dissolved iron and manganese were measured in October 1995 in the north–east wake of the Kerguelen archipelago (48°40′–49°40′S, 68°70′–70°50′E), an area that shows high phytoplankton biomass (CZCS and SeaWiFS data) in the middle of the High Nutrient Low Chlorophyll (HNLC) Southern Ocean. The study area (about 25,000 km2) comprised a branch of the Polar Front with Antarctic surface water (AASW) intruding northward, shouldering the shelf break of the Kerguelen Plateau. The coastal zone was clearly affected by material of lithogenic origin (riverine discharges, soil leaching by rain waters, aeolian inputs), as well as by inputs from the sediments (effluxes from the sediment–water interface, resuspension from the sediments), its near surface waters showing considerable enrichment in dissolved iron (5.3–12.6 nM) and in dissolved manganese (2.9–8.6 nM). The offshore waters, although less enriched in trace-metals, were also affected by trace-metal inputs from coastal and continental shelf origin. Dissolved iron and manganese concentrations in these waters were 0.46–0.71 and 0.68–1.3 nM, i.e. far over typical antarctic open ocean surface water concentrations of 0.16 nM for iron [Martin, J.H., Gordon, R.M., Fitzwater, S.E., 1990. Iron in Antarctic waters. Nature, 345: 156–158.] and around 0.1 nM for manganese [Martin, J.H., Gordon, R.M., Fitzwater, S.E., 1990. Iron in Antarctic waters. Nature, 345: 156–158; Sedwick, P.N., Edwards, P.R., Mackey, D.J., Griffiths, F.B., Parslow, J.S., 1997. Iron and manganese in surface waters of the Australian subantarctic region. Deep-Sea Res., 44: 1239–1253.]. The dissolved iron enrichment in coastal waters of the Kerguelen Islands is much more important (about 10 times for dissolved iron) than for the Galapagos Islands, another oasis in the HNLC Equatorial oceanic system, where the concentration increase in dissolved iron in the surface waters around the islands is mostly driven by upwelling of the Equatorial Under Current (EUC) as it reaches the Galapagos Platform. 相似文献
19.
20.
利用海底有缆在线观测系统获得的连续实时观测数据，研究了2016年6月2日至10月22日期间威海市西港海洋牧场底层海水溶解氧浓度的时间变化特征，并探讨了其影响机制。结果表明，观测期间底层海水溶解氧浓度整体呈先减小后增大的变化趋势，其变化范围为2.99 mg/L至11.43 mg/L，均值约为6.65 mg/L。进一步分析表明：（1）底层海水饱和溶解氧浓度的变化并不显著，于6月出现过饱和现象；（2）海水温度是底层海水溶解氧浓度日际变化和月变化的主要影响因素；（3）7月至8月中旬，在季节性温跃层抑制垂向混合和水温升高的共同影响下，底层溶解氧浓度总体呈下降趋势；（4）日平均风速与日平均海水溶解氧浓度的相关性并不显著，但大风期间底层海水溶解氧浓度存在先升高后降低的变化特征；（5）底层海水溶解氧浓度的日变化以全日周期为主，可能主要受生物过程、垂向混合扩散和潮流输运等日变化的影响。本研究对于进一步探讨山东半岛海洋牧场区域海水溶解氧的时空分布特征及其影响机制具有重要意义。 相似文献