Copper in the resurrection fjord, Alaska

Copper concentrations have been measured in more than 200 samples collected from an Alaskan fjord and continental shelf and slope regions in the northwestern Gulf of Alaska. Concentrations were lowest (2·1 nmol kg⁻¹) at depths of 400–1000 m in the continental slope waters of the Gulf of Alaska. Copper increased systematically with decreasing salinities shoreward to concentrations >30 nmol kg⁻¹ in fjord surface waters during summer months of high freshwater runoff. Copper concentrations increased with depth at an inner fjord station where deep basin waters have restricted circulation, and these data together with surface (<5 cm) pore water copper concentrations (mean=122 nmol kg⁻¹) about an order of magnitude higher than bottom water copper concentrations are indicative of a flux of copper across the sediment-seawater interface. This latter was estimated at 32±12 nmol cm⁻² annually, and represented less than 20% of the annual input to fjord surface water (228–411 nmol cm⁻²) added during summer months. Mass balances in bottom waters indicate a vigorous recycling of copper with a residence time estimated at 21±11 days. Most copper that is remobilized in surface sediments is returned to bottom waters and little (3%) is removed by subsequent diagenetic reaction in the buried sediments. However, an estimate of copper accumulating in anoxic fjord sediments was comparable with copper added to fjord surface waters suggesting that input-removal reactions rather than internal cycling controls copper geochemistry in this estuary.     

Tidally generated sea-floor lineations in Bristol Bay, Alaska, USA

Highly reflective linear features occur in water depths of 20–30 m in northern Bristol Bay (Alaska, USA) and are, in places, over 600 m in length. Their length-to-width ratio is over 100:1. The lineations are usually characterized by large transverse ripples with wavelengths of 1–2 m. The lineations trend about N60°E, and are spaced between 20 and 350 m. Main tidal directions near the lineations are N60°E (flood) and S45°W (ebb), which are parallel to subparallel to the lineations. They suggest that the lineations may be tidally generated. The lineations may be bright sonar reflections from a winnowed lag concentrate of coarse sand.     

In situ observations of wave pumping of sediments in the Yellow River Delta with a newly developed benthic chamber

A specially designed benthic chamber for the field observation of sediment resuspension that is caused by the wave-induced oscillatory seepage effect (i.e., the wave pumping of sediments) is newly developed. Observational results from the first sea trial prove that the geometry design and skillful instrumentation of the chamber well realize the goal of monitoring the wave pumping of sediments (WPS) continuously. Based on this field dataset, the quantitative contribution of the WPS to the total sediment resuspension is estimated to be 20–60% merely under the continuous action of normal waves (H_s ≤ 1.5 m) in the subaqueous Yellow River Delta (YRD). Such a large contribution invalidates a commonly held opinion that sediments are purely eroded from the seabed surface by the horizontal “shearing effect” from the wave orbital or current velocities. In fact, a considerable amount of sediments could originate from the shallow subsurface of seabed driven by the vertical “pumping effect” of the wave-generated seepage flows during wavy periods. According to the new findings, an improved conceptual model for the resuspension mechanisms of silty sediments under various hydrodynamics is proposed for the first time.     

潮滩上波高的时空变化及其影响因素——以长江三角洲海岸为例

于2009—2010年的不同季节在崇明东滩北部、中部、南部以及杭州湾北岸东段的芦潮港岸段,利用目前先进的SBE 26plus浪潮仪进行了多个潮周期的波浪观测。研究表明,观测期间潮周期平均风速为1.9～11.0m/s、最大风速为2.8～12.1m/s,各测点潮周期平均水深为0.28～2.12m,高潮位最大水深为0.37～3.19m,潮周期有效波高为0.03～0.45m,最大波高为0.08～1.59m。波高的时空变化受风速、风向、水深和岸滩坡度的综合影响。通常情况下,向岸风期间的波浪较大;风速、水深、岸滩坡度越大,潮滩上的波高也越大。空间上,岸滩坡度最小的崇明东滩中部(坡度0.6‰)测点波高和水深之间的相关性最好,岸滩坡度最大的芦潮港潮滩(坡度8.7‰)测点两者间的相关性最差。时间上,波高和水深之间的相关性与风速、风向的变化有关。因此,只有在潮滩坡度较小(例如<1‰),风速、风向较为稳定时,波高和水深之间的显著正相关关系才存在。要了解某个潮滩的波浪特征,有必要利用先进的仪器进行系统的原位观测,而非简单地借助其它潮滩的波浪研究结果。研究推断,在向岸强台风和大潮高潮位阶段,崇明东滩中潮线附近的最大波高可达1.5～2.0m,芦潮港堤外潮滩的最大波高可达2m以上。     

海南岛南渡江三角洲的废弃与侵蚀

讨论了海南岛南渡江三角洲由发展到废弃的演化过程,分析了不同废弃阶段的河口平面形态由东向西变化等特征,对比活动三角洲与废弃三角洲的显着地貌差异.此外还讨论了活动三角洲前缘潮流在岸外较深水区的侵蚀作用和泥沙的向东搬运,以及波浪在近岸较浅水区的侵蚀作用和泥沙的向西和向岸的搬运.     

Impacts of neoliberal policies on non-market fishing economies on the Yukon River,Alaska

This paper describes how and why a relatively minor, mostly native non-market economy founded on subsistence-caught Chinook salmon in Alaska has become the object of controversy and increasing regulatory pressure. Small-scale exchanges of cash for subsistence-caught fish conflict with a neoliberal emphasis on markets, profit maximization, and private property. This paper clarifies the role of neoliberal policies in shaping and even causing the controversy over these exchanges, and the consequences for management of Chinook salmon on the Yukon River.     

九龙江口红树林区底栖动物的生态

根据1987年2、5、8、11月的调查资料,研究了福建九龙江口红树林区底栖动物生态。结果表明,该区共有底栖动物172种,主要由多毛类、软体动物和甲壳动物组成,以近岸广盐性种类占优势。平均生物量和栖息密度分别为48.03g/m~2和311个/m~2,以甲壳动物占优势;数量的季节变化显著;中潮区数量较大。潮汐、盐度和沉积物是影响本区底栖动物分布的主要因素。     

Organic wastewater effects on benthic invertebrates in the Manawatu River

The effects of the 3 main wastewater discharges on the benthic fauna of the Manawatu River were studied between March 1979 and January 1980. At least 4 replicate Surber samples were taken from each of 6 sites, on 5 occasions during this period. Deleatidium sp. (Ephemeroptera), Hydora sp. (Coleoptera), and the Chironomidae were the most useful indicator organisms, according to a ranking system based on the occurrence of significant differences (P<0.05) between populations at different sites. These taxa exhibited significant differences between sites in about 70% of all inter‐site comparisons, using Mann‐Whitney U‐tests. The Coefficient of Similarity was successful at summarising the comparisons between the clean‐water and down‐stream sites, ranging between 95% similarity to the clean‐water site for a recovery site in winter, and less than 10% similarity to the clean water site for the lower reaches in summer. It is suggested that relative indices may be more appropriate than absolute indices for measuring water pollution. Water quality, indicated by species diversity, was generally good (allowing for the effects of agricultural runoff), although midsummer organic loading induced marked changes in benthic species composition, including the disappearance of Deleatidium sp. from several sites.     

Flocculation and sedimentation on the Po River Delta

With the goal of improving understanding of the effect of flocculation on the formation of fine-grained deposits on continental shelves, hydrographic profiling, in situ imaging of suspended matter, and collection of surficial sediment samples were conducted at the Po River Delta in June 2001. These data show that during medium flow conditions (1920 m³/s), sedimentation occurs rapidly immediately offshore of the main distributary, Po della Pila. Rapid sedimentation is promoted by large rapidly sinking flocs forming in the river well upstream of the mouth. The delivery of fine sediment to the seabed at the mouth of the Po is sufficient to overwhelm the erosive effects of waves and currents, leading to accumulation of mud in water depths as shallow as 4 m. On cross-shelf transects 2 km north and south of the mouth, however, suspended sediment supply from the river is reduced to the point that mud accumulates only seaward of the 8-m isobath. Along the central transect, suspended sediment concentration decreases rapidly seaward of the 6-m isobath where the emergence of a more organic-rich population of flocs along a mid-water density interface is suggested. Energetic activity along the 15-m isobath likely promotes resuspension with the potential for removal of material from the delta. Further investigation of floc properties, namely the relationship of floc size to settling velocity, is necessary to establish the degree to which the suspension is flocculated during transport and deposition.     

黄河三角洲地区地下水分析

在全面收集有关黄河三角洲地区水资源方面文献资料的基础上，从含水层、地下水水质、地下水循环和地下水年内动态变化4个方面，详细论述了黄河三角洲地区地下水的基本特征，并将黄河三角洲地区地下水含水层划分为3个大的水文单元，提出了地下水以河道为分水岭呈扇形向海排泄的特征。     

Delta lobe degradation and hurricane impacts governing large-scale coastal behavior,South-central Louisiana,USA

A large deficit in the coastal sediment budget, high rates of relative sea-level rise (~0.9 cm/year), and storm-induced current and wave erosion are forcing barrier shoreface retreat along the periphery of the Mississippi River delta plain. Additionally, conversion of interior wetlands to open water has increased the bay tidal prism, resulting in degradation of barrier islands due to inlet widening, formation of new inlets, and sediment sequestration at ebb-tidal deltas. Single-beam bathymetric surveys along a 165-km stretch of south-central Louisiana barrier coast, from Raccoon Point in Terrebonne Parish to Sandy Point in Plaquemines Parish, were conducted in 2006. These data, combined with historical bathymetry from three time periods (dating to the 1880s), provide a series of digital elevation models that were used to calculate sediment volumetric changes and determine long-term erosional-depositional trends. Dominant patterns during the 125-year period include (1) erosion of ~1.6 × 10⁹ m³ from the shoreface, forcing up to 3 km of shoreface retreat, (2) sediment deposition in coastal bights and at ebb-tidal deltas, and (3) a combined increase in tidal inlet cross-sectional area from ~41,400 m² to ~139,500 m². Bathymetric and shoreline change datasets separated by shorter time periods (sub-annual) demonstrate that these long-term trends are driven by processes associated with major hurricane impacts, and that rates of shoreface erosion are an order of magnitude greater during active hurricane seasons compared to long-term trends.     

Natural and Anthropic Middle-term Variations in the Delta System at the Mouth of the Goro River (Po Delta, Italy)

Abstract. The modern delta system of the Po River is the result of an evolution strictly controlled by anthropic factors and mainly developed during a period of climatic deterioration (Little Ice Age 1550/1850).
At the beginning of the 17^th century the main branch of the Po River, Fornaci Po, was modified with the "Cut of Viro" in order to avoid landfill of the Venetian Lagoon. Simultaneously, the southernmost branch of Ariano, or Goro, was forced to flow southwards. Subsequent sedimentary variations, caused by changes in the climatic conditions, contributed to make the area supplied by the Goro Po River increasingly lagoonary. In the second half of the 19^th century (end of the Little Ice Age – L.I.A. –), the first coastal spits started to take shape and developed in different systems throughout the entire following century. Coastal spits turned out to produce in the original bay, a progressive closure towards the sea. The strong decrease in solid loads, characterising the second half of the 20^th century and mainly due to anthropic factors, marks the beginning of a new phase extending to the overall Po Delta system, in which the mouth layout is controlled by wave energy.     

Advective pore water input of nutrients to the Satilla River Estuary,Georgia, USA

In situ benthic flux measurements, pore water nutrient profiles, water column nutrient distributions, sediment grain size distributions and side-scan sonar observations suggest that advective transport of pore waters may be a major input pathway of nutrients into the Satilla River Estuary (coastal Georgia, USA). In situ benthic chamber incubations demonstrate the occurrence of highly variable, but occasionally very large sea floor fluxes of silicate, phosphate, and ammonium. Locally occurring benthic microbial mineralization of organic matter, as estimated by S³⁵-sulphate reduction rate measurements, is insufficient to support these large fluxes. We hypothesize that the observed interlayering of permeable, sandy sediments with fine-grained, organic-rich sediments in the estuary provides conduits for advective transport of pore water constituents out of the sediments. Because permeable layers may extend significant distances beneath the salt marsh, the large fluxes observed may be supported by remineralization occurring over large areas adjacent to the estuary. Advective transport may be induced by pressure gradients generated by a variety of processes, including landward recharge by meteoric or rain waters if sand layers extend far enough into the maritime coastal lands. Alternatively, tidal variations across the salt marsh sediment surface may hydraulically pump water through the sediment system. Because these fluxes appear to be concentrated into small layers, this source may be a significant input of nutrients to the estuary even if permeable, sandy layers comprise a very small proportion of the seabed.     

黄河三角洲北部岸滩的侵蚀演变

为研究黄河三角洲海底冲刷演变规律,2004年6月和9月,在黄河三角洲北部、飞雁滩以东岸段进行了2次共21条水深剖面测线的调查工作。通过1985年、1999年两期历史水深资料与本次实测水深资料的对比研究发现:自1985年以来,研究区一直处于冲蚀状态,1999年以后局部区域出现微弱淤积,侵蚀中心逐渐向东南、向岸迁移。测区总体演变趋势以侵蚀为主,强度逐渐减弱,并向冲淤平衡缓慢过渡。     

Evolution of Modern Yellow River Delta Coast

This paper deals with the development and evolution of modem Yellow River delta and the erosion or deposition rates of its different sections. In June, 1996.Yellow Rivers terminal course was artificially turned eastwards to empty into the sea and then the 1 lth lobe of the modem Yellow River delta began to form. This course change may mark the beginning of the 3rd subdelta formation. As a result of that. the Yellow River delta advances towards east by north with the 1st, 2nd and 3rd subdeltas arranged in succession. Coast zone in the deltaic area is divided into 7 different sections according to their different erosion or deposition rates: the relatively stable section from Dakou River to Shunjiang Stream, the weakly retreating section from Shunjiang Stream to the Tiaohe River mouth, the strongly retreating section from the Tiaohe River mouth to the station 106. the artificially stable section due to stone dam protection from the station 106 to Gudong Oilfield, the strong deposition section from Gudong Oilfield to Dawenliu Haipu, the weakly deposition section from Dawenliu Haipu to the Zimai Stream mouth, and the stable section from the Zimai Stream mouth to the Jiaolai River mouth. It is predicted that the erosion and deposition situations of the sections will nearly remain the same in 10 years, but the retreating and silting-up rates will tend to become slower gradually. Human activities have an evident influence on the changes of the coastline.     

古代黄河三角洲海岸的现代特征--黄河三角洲潮滩时空谱系研究I

从冀鲁交界的大口河口向东至顺江沟为蜿蜒120 km的粉沙淤泥质海岸。作者先后于1987、1992和2000年对该海岸进行了多次实地考察，并应用80年代至90年代末以来的航空和卫星遥感等资料对其进行了综合分析。公元11～1128年，黄河尾闾在此摆动入海，形成河口滩型海岸。1128年以后，黄河自此迁走，在海洋动力作用下，由河口滩型海岸逐渐演变成为典型的潮滩型海岸。该岸段海岸发育了广阔平坦的、相带十分明显的潮滩地带。在潮滩上同时发育了岛链状贝壳堤、残留冲积岛和巨大的多级分叉贯通性的潮水沟网络，构成了独具特色的海岸地貌环境体系，即黄河三角洲潮滩海岸时空谱系中的古代黄河三角洲海岸。     

Intertidal meiofauna of Jeju Island,Korea

For the first time, the structure of the meiobenthos community and marine nematodes in particular was investigated in the different intertidal zones of Jeju Island (South Sea of Korea). A relationship was found between the density of meiobenthic communities and the type of the bottom sediment. In addition, in the silty sediments, nematodes were dominant, while in the sandy sediments harpacticoids and ostracods were dominant groups. Sixty eight species belonging to 60 genera and 19 families of nematodes were found in the whole area. Four different nematode taxocenosis were distinguished using a cluster analysis. Dominant feeding groups were omnivores (2B) and epistratum-feeders (2A). The highest number of non-selective deposit-feeders (1B) was detected in the lagoon with the bottom silty sediments.     

黄河三角洲表层土壤重金属环境质量评价

主要针对黄河三角洲表层土壤及沉积物的重金属分布调查,在2006~2008年间采集表层土壤样品219个(其中浅海湿地25个),并运用受普遍认可的生态危害指数法、单因子及内梅罗污染指数法对黄河三角洲整体进行环境质量评价,得出以下结论:(1)黄河三角洲表层土壤中重金属元素的污染指数从高到低为:CrPbZnAsCuCdHg;(2)浅海湿地的近海表层沉积物中的重金属元素含量较上三角洲平原的表层土壤低,前者最大影响来源于As,土壤样品一级标准率达到96%;后者的最大威胁是As和Cd,土壤样品一级标准率达到88.5%;(3)黄河三角洲表层土壤及近海沉积物的Eri值、RI值、单因子污染指数及综合污染指数均较小,远未达到轻微污染的标准,表明黄河三角洲土壤环境状况较好,整体处于清洁水平。     

黄河三角洲地区地面沉降驱动因素研究

黄河三角洲地区地势低平、生态脆弱, 地面沉降使得海水入侵和风暴潮灾害加剧。弄清该区域地面沉降驱动因素, 对油田安全生产和湿地生态保护都有积极的意义。以20 m 地层为界, 将地面沉降驱动因素分为浅地层和深地层因素。分析了地表荷载增加、地下水和油气开采、沉积物固结压实、新构造运动等对该区地面沉降的驱动作用。此外, 探讨了海平面上升和地震灾害对该区地面沉降的影响。结果表明: 该区地面沉降驱动因素主要为沉积物固结和地下水开采, 但控制范围存在区域性差异;1969 年地震使该区产生明显地面沉降, 海平面上升使该区地面沉降形势更加严峻。