共查询到19条相似文献，搜索用时 46 毫秒
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长江河口段徐六泾水文站潮流量整编代表线法研究 总被引：4，自引：1，他引：3
长江河口段河道宽阔,断面几何形状复杂,水流往复流动,水力条件变化复杂,潮流量测验及整编一直是难题。随着多普勒剖面流速仪（ADCP）在技术上日益完善以及无线通讯技术的快速发展,解决长江河口段徐六泾水文站潮流量测验及整编问题具备了切实可行的技术条件。经过近两年的努力,根据代表线法测流原理,采用浮标ADCP结合平台ADCP的测流系统,徐六泾水文站成功地实现了断面流量、流速的实时监测,潮流量整编成果达到了规范要求。 相似文献
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除了内陆河以外,河流最终都将汇入海洋。在这里,河流和海洋动力同时起着作用,形成特殊的景观。总的来看,河口地区是一个淤积的环境。泥沙淤积对泄洪、排沙及航运等方面的影响,就是河口的主要泥沙问题。根据“形态与成因”相结合的原则,以河口的水 相似文献
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国外河口最大浑浊带生物地球化学研究的动态 总被引：4，自引：0，他引：4
河口最大浑浊带（ＴｕｒｂｉｄｉｔｙＭａｘｉｍｕｍ,以下简称ＴＭ）在全世界不论高纬度地区或低纬度地区,各种气候类型和潮汐条件下的河口均有发现,尤其在部分混合型和垂向均匀混合型河口更为发育。其中包括不同形状和大小的河口,从小河口到诸如亚马逊河、密西西比河... 相似文献
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长江与黄河河口沉积物磁性特征对比的初步研究 总被引：11，自引：1，他引：10
根据2001年8月和9月分别采自黄河与长江河口沉积物样品的磁性测量和粒度分析,探讨长江和黄河河口沉积物的磁性特征及其差异。长江河口沉积物中亚铁磁性物质的含量高于黄河口,但长江口与黄河口沉积物中都是亚铁磁性矿物主导了样品磁性特征,亚铁磁性矿物晶粒都以假单畴-多畴为主。相比黄河口沉积物,长江口沉积物不完整反铁磁性物质对磁性特征的的贡献较小。长江与黄河河口的这种磁性特征主要反映了不同的沉积物来源的控制影响。此外,无论是长江口还是黄河口沉积物,磁性参数χARM、χfd%与沉积物细粒级组分存在显著的相关性,表明这两个参数作为粒度的代用指标具有普遍性。 相似文献
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河口盐水入侵作用研究动态综述 总被引：9，自引：0，他引：9
河口是河流径流与海洋水体交接的过滤地带。由于水流扩散，挟沙能力降低，河流挟带的泥沙进入河口后将逐渐沉降。但沉降的泥沙常在某段槽床聚积，形成拦门沙坝而阻碍航运。拦门沙形成的原因与河口环流、泥沙絮凝沉降和最大混浊带等现象紧密关联，而这些现象又由盐水入使所造成。本文综述了国内外对河口盐水入侵作用的认识和研究进展，以及目前的研究动态。 相似文献
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我国河口基本水文特征分析 总被引：1，自引：0，他引：1
我国海岸线漫长,人海河口众多。据统计,在长达32000公里的大陆与岛屿海岸线上,分布着大小河口1800多个,仅河流长度在100公里以上的河口就有60多个,其中长江口、黄河口、珠江口、钱塘江口等都是各具典型的世界著名河口. 河口地区交通便捷,资源丰富,经济繁 相似文献
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The Arctic Ocean Estuary 总被引：1，自引：0，他引：1
James W. McClelland R. M. Holmes K. H. Dunton R. W. Macdonald 《Estuaries and Coasts》2012,35(2):353-368
Large freshwater contributions to the Arctic Ocean from a variety of sources combine in what is, by global standards, a remarkably
small ocean basin. Indeed, the Arctic Ocean receives ∼11% of global river discharge while accounting for only ∼1% of global
ocean volume. As a consequence, estuarine gradients are a defining feature not only near-shore, but throughout the Arctic
Ocean. Sea-ice dynamics also play a pivotal role in the salinity regime, adding salt to the underlying water during ice formation
and releasing fresh water during ice thaw. Our understanding of physical–chemical–biological interactions within this complex
system is rapidly advancing. However, much of the estuarine research to date has focused on summer, open water conditions.
Furthermore, our current conceptual model for Arctic estuaries is primarily based on studies of a few major river inflows.
Future advancement of estuarine research in the Arctic requires concerted seasonal coverage as well as a commitment to working
within a broader range of systems. With clear signals of climate change occurring in the Arctic and greater changes anticipated
in the future, there is good reason to accelerate estuarine research efforts in the region. In particular, elucidating estuarine
dynamics across the near-shore to ocean-wide domains is vital for understanding potential climate impacts on local ecosystems
as well as broader climate feedbacks associated with storage and release of fresh water and carbon. 相似文献
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Heavy metals in the Derwent Estuary 总被引：2，自引：0，他引：2
Analyses of the concentrations of Cd, Cr, Co, Cu, Fe, Pb, Mn, Hg, Ni, and Zn in filtered waters, suspended particulates, sediments,
shellfish, fish, airborne particulates, and sewage have confirmed work of other investigators showing that the Derwent Estuary
is heavily contaminated, particularly withmercury, cadmium, lead, andzinc, and have added further information regarding the distribution of each metal. Apparently most of the contamination originated
from the earlier operation of a zinc refining plant. A study of shellfish growing in variously contaminated regions found
that more than 20 species could be listed in order of their respective abilities to accumulate each heavy metal. For example,
the mussel (Mytilus edulis) was found to be a good indicator of cadmium and mercury contamination, but less valuable as an indicator of zinc. The surf
barnacle, (Catophragmus polymerus) was found to be one of the most sensitive biological indicators of cadmium contamination. An indication of the steps by
which a waste metal is eventually accumulated at high and even toxic concentrations in seafoods, may be seen from a comparison
of the relative concentrations of cadmium, lead, mercury, and zinc found in mussels, sediments, suspended particulates, and
filtered waters. The high concentrations recorded for metals include: 1,100 μg/g Hg, 10,000 μg/g Zn, and 862 μg/g Cd in dried
sediments; 1,500 μg/g Cd in airborne dust fallout; 200 μg/g Cd and 100,000 μg/g Zn in dried oysters; and 16 μg/l Hg, 15 μg/l
Cd and 1,500 μg/l Zn in filtered waters. 相似文献
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The composition of the zooplankton community in a macrotidal (8 m tidal range), tropical estuarine system (Darwin Harbour,
Australia; 12o28′ S, 130o50′ E) was studied over a 2 year period with the goal of describing biodiversity and determining the environmental factors
that have the greatest impact on community structure. Most (82–84%) of the >73 μm plankton was composed of copepod nauplii
and copepodites, and plankton samples taken with larger, coarser meshed (150 and 350 μm) nets did not contain significant
numbers of larger (non-copepod) organisms. In all, 32 copepod species were recorded, with small euryhaline marine copepod
species such as Parvocalanus crassirostris, Bestiolina similis and Oithona aruensis dominating the zooplankton. Plankton abundances ranged between 30,000 and 110,000 m−3, and there were significant year (2003 > 2004), season (wet > dry) and site differences (inner harbour sites > outer harbour
sites), but negligible diurnal differences. Multivariate analyses identified three sample groups: (1) middle and outer harbour
sites, (2) inner harbour and river sites and (3) the river site during the wet seasons. Middle and outer harbour stations
were characterised by a diverse mixture of coastal copepods, whereas inner harbour and river sites were dominated by P. crassirostris and O. aruensis. During the wet season, there was a distinct copepod community within the Blackmore River, dominated by Acartia sinjiensis, Oithona nishidai and Pseudodiaptomus spp. Environmental variables (nutrients and chlorophyll a) were correlated with salinity, which had the strongest influence on community structure. There was a significant drop in
species richness from harbour to river sites. Small copepods of the families Paracalanidae and Oithonidae dominate tide-dominated
Australian tropical estuaries, whereas copepods belonging to the family Centropagidae (such as Gladioferens spp.) appear to be characteristic of wave-dominated estuaries in southern Australia. 相似文献
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元素地球化学是沉积物源判别和环境研究的重要手段,但河口海岸地区沉积动力环境复杂多变,人类活动影响强烈,全岩沉积地球化学的示踪研究存在局限性和多解性。选择长江下游干流悬浮物、东海陆架表层沉积物以及长江口具有一百多年沉积记录的ZK6孔,通过化学相态分析（1 N HCl处理）,探究酸溶态微量元素组成特征及其对河口环境变迁的指示。相较于钻孔全岩样品,酸溶态Sr/Ba比能更可靠地反映河口古盐度和海陆相沉积环境的变化。ZK6孔沉积物酸溶态稀土元素（REE）主要赋存于Mn氧化物中,Mn、ΣREE含量、Ce/Ce*以及Sr/Ba比在1899—2007年间呈三段式变化,主要反映长江河口流路分汊和主泓位置改变引起的河口沉积环境变化,进而影响河口环境中活跃元素和次生组分在沉积地层中的保存记录。该研究对今后深化认识复杂河口环境下微量元素地球化学行为以及微量元素示踪海洋环境变化具有借鉴意义。 相似文献
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Enrique M. Padilla Manuel Díez-Minguito Miguel Ortega-Sánchez Miguel A. Losada 《Estuaries and Coasts》2016,39(3):605-620
This paper analyzes thermal energy transport in the narrow and tidally energetic Guadalquivir River Estuary (SW Spain). Measurements from a comprehensive monitoring campaign (2008–2011) reveal the forcing factors of the temperature field and its spatio-temporal variability. The along-channel thermal energy gradient reaches magnitudes of ～375 J/m4 near the mouth during the summer and winter. The water temperature is primarily controlled by shortwave radiation, latent heat transfer through the free surface, and tidal advection, whereas it depends less on freshwater discharge and longitudinal dispersion. The tidally averaged effective longitudinal thermal dispersion coefficient was evaluated at several stretches for each tidal cycle. The mean values of the coefficient tend to increase landward and are on the order of ～103, larger than (but of the same order of magnitude as) the salinity coefficient values. Based on these analyses, a deterministic operational model for thermal energy transport was developed. The model solves the tidally and cross-sectionally averaged advection–dispersion equation for the thermal energy balance and obtains accurate fits of the subtidal temperature field at any location within the estuary. The modeled water temperatures agreed well with the observations at all the stations (coefficients of determination, R 2 greater than 0.98), even after the seasonal oscillation in radiation was removed (R 2?>?0.77). 相似文献
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Dissolved carbon monoxide, [CO], was measured in oxic surface waters and in the anoxic layer of the Pettaquamscutt River, Rhode Island, from March to August 2008. Samples were collected at near-shore locations to examine spatial and seasonal changes at solar noon. Each month, a set of diel samples was collected at the surface stations to evaluate photoproduction and biological processing. In July and August, anoxic samples from depths >6 m were collected to examine the presence of an active anaerobic CO metabolism. The surface [CO] decreased from 65 to 5 nmol kg?1 from spring to summer, which was attributed to a decline in dissolved organic matter. Diel [CO] showed a strong mid-afternoon maximum with a late evening and early morning minimum. Inferred first-order loss rates, attributed to biological processing, ranged from 0.1–0.6 h?1 without a clear seasonal pattern. [CO] saturation ratios were typically >200 at mid-day, >7 in morning/late evening, and never below 1, implying the river is always a net source of CO to the atmosphere. [CO] in the anoxic layer averaged 2 nmol kg?1. 相似文献
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Aurélie Chaalali Grégory Beaugrand Philippe Boët Benoît Sautour 《Estuaries and Coasts》2013,36(6):1193-1205
Although many consequences of climate change on marine and terrestrial ecosystems are well documented, the characterisation of estuarine ecosystems specific responses and the drivers of the changes are less understood. In this study, we considered the biggest Southwestern European estuary, the Gironde, as a model of a macrotidal estuary to assess the effects of both large- (i.e., North Atlantic basin-scale) and regional-scale climate changes. Using a unique set of data on climatic, physical, chemical and biological parameters for the period 1978–2009, we examined relations between changes in both the physical and chemical environments and pelagic communities (plankton and fish) via an end-to-end approach. Our results show that the estuary experienced two abrupt shifts (～1987 and ～2000) over the last three decades, which altered the whole system. The timing of these abrupt shifts are in accordance with abrupt shifts reported in both marine (e.g., in the North Sea, the Mediterranean Sea and along the Atlantic) and terrestrial (e.g., in European lakes) realms. Although this work does not allow a full understanding of the dynamical processes through which climate effects propagate along the different compartments of the ecosystem, it provides evidence that the dynamics of the largest estuary of Southwest Europe is strongly modulated by climate change at both regional and global scales. 相似文献