Sea-level, sediment supply and coastal changes: Examples from the coast of Ireland

Sediment supply and pre-existing shoreline morphology are crucial factors in controlling coastal changes due to sea-level rise. Using examples from both southeast and northeast Ireland, it can be shown that sea-level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium. Cliff erosion and longshore sediment movement in east Co. Wexford has led to injection of sediment onto the shelf, and the growth, under both wave and tide regimes, of linear offshore shoals. These shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea-level rise. In contrast, the nearby coast of south Co. Wexford comprises a series of coarse clastic barriers moving monotonously onshore, via overwash processes. Here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms. Finally, the rock platform coast of Co. Antrim presents a far more resistant shoreline to incident marine processes, yet even here there is strong evidence of present process control over so-called ‘raised’ platforms and embayments. It is concluded that coastal sediment supply and dynamics, together with coastal morphology and its interaction with waves, present a far more complex variety of sea-level indicators than is normally acknowledged.     

Bioaccumulation of heavy metals by bivalves from Limski Kanal (North Adriatic Sea). II. Copper distribution between oysters, Ostrea edulis, and ambient water

Accumulation of copper was studied between June 1979 and June 1980 in the oyster Ostrea edulis Linnaeus, cultivated in the Limski Kanal, on the Istria Peninsula (Yugoslavia).The copper distribution in different organs of oysters of the same age was compared with concentrations of copper existing in different physicochemical forms in ambient sea water, i.e., dissolved Cu in labile complexes determined at the natural pH of 8; ‘total’ dissolved Cu determined after acidification to pH 2; and Cu bound to suspended particles with a diameter above 0.45 μm. Copper concentrations in the water were determined by differential pulse anodic stripping voltammetry (DPASV) and in analyses of biotic material, graphite furnace atomic absorption spectrometry (GFAAS) was applied.Significant correlations have been found between copper complexed with dissolved organic ligands and its concentration in the soft part of the oyster. Copper contents increase gradually with the weight of the organs until enhanced gametogenetic activity of the oysters occurs. Thereafter the correlation factor between copper contents and the size of body parts varied significantly with the season.     

Phytoplankton production in two east coast estuaries: Photosynthesis-light functions and patterns of carbon assimilation in Chesapeake and Delaware Bays

Chesapeake Bay is a large and productive estuary that has received close scrutiny in recent years because of indications that its water quality and biota have been damaged by man's activities. Data on primary production for the estuary as a whole, however, are surprisingly sparse. We describe here the distribution of photosynthetic carbon assimilation by phytoplankton in Chesapeake Bay, and relate productivity patterns to hydrographic characteristics of the estuary. Between March 1982 and April 1983, a series of four cruises was conducted on Chesapeake Bay, and two cruises on the urbanized Delaware Bay for comparison. The upper Chesapeake and Delaware were highly turbid with high concentrations of suspended particulate matter and dissolved inorganic nutrients. Low chlorophyll concentrations were usually found in these areas of high turbidity, despite the abundance of nutrients, suggesting light limitation. Application of Wofsy's (1983) model of phytoplanton growth confirmed this suggestion. Chlorophyll and productivity maxima usually occurred seaward of the turbidity maxima where light penetration increased and suffient nutrients were present to support active phytoplankton growth. Further seaward of the chlorophyll maxima in the Chesapeake, the photic zone depth increased, concentrations of nutrients decreased, and phytoplankton biomass decreased, suggesting that nutrient availability, rather than light, controlled phytoplankton growth in the lower portion of the estuary. In contrast to the Chesapeake, Delaware Bay was more turbid, had generally higher nutrient concentrations, and was lower in phytoplankton productivity. The chlorophyll maxima and region of rapid phytoplankton growth occurred further toward the lower estuary and shelf regions in Delaware Bay because the high turbidity extended further seaward. Nutrients were never depleted at the shelf end of the estuary sufficiently to retard phytoplankton growth. Photosynthesis-irradiance (P-I) curves from simulated in situ and constant intensity incubations showed a strong correlation of the light-limited slope (a^B) with the light-saturated rate ( ) on each cruise. Spatial variations in corresponded to patterns of phytoplankton abundance, as did integral production (PP) and carbon-based growth rates (μ_C, μ_m), and photosynthetic parameters varied significantly with temperature.     

Trophic accumulation and depuration of mercury by blue crabs (Callinectes sapidus) and pink shrimp (Penaeus duorarum)

Mercury concentrations in blue crabs (Callinectes sapidus) collected from an area of mercury-contaminated sediments in Lavaca Bay, TX, USA, are more than an order of magnitude greater than concentrations in penaeid shrimp from the same area. Laboratory feeding experiments using mercury-contaminated fish as food showed that both blue crabs and pink shrimp (Penaeus duorarum) could accumulate mercury concentrations comparable to those in their food in 28 days. Calculated mercury assimilation efficiencies averaged 76% for blue crabs and 72% for pink shrimp. Significant depuration of mercury by blue crabs was not observed during a subsequent 28-day period, but pink shrimp lost mercury at a rate of about 0.012 day-1. Model calculations predict biomagnification factors of mercury of about two to three at steady state for both species. The large difference in observed concentrations of mercury in field-collected blue crabs and penaeid shrimp does not result from differences in efficiency of mercury assimilation from their food or from differences in excretion rates. It is more likely the result of differences in residence times in the contaminated area and of differences in feeding habits.     

Field Placement and Evaluation of Stabilized Dredged Material (SDM) from the New York/New Jersey Harbor

Since the 1997 local ban on ocean dumping of dredged sediments, the States of New York and New Jersey have pursued a policy of environmentally sound solutions to the management of dredged material, including beneficial use of stabilized dredged material (SDM) in transportation applications. A pilot study was initiated in 1998 to evaluate the use of SDM in the construction of highway embankments. Utilizing 80,000 cubic yards of dredged material, two embankments were constructed from SDM on a commercial development area adjacent to the Harbor. Geotechnical properties and handling of SDM were evaluated both during and one year post - construction. This article presents the evaluation of the embankments themselves, including constructability and performance. The results demonstrate that SDM satisfies most of the geotechnical criteria for fill construction, except those for durability, requiring proper coverage and protection similar to that provided for fills constructed on cohesive soils. This same characteristic precludes long term stockpiling of SDM prior to final placement, limiting applications to those that have schedules overlapping with dredging projects. Increased costs for the use of SDM can be as high as $8 per cubic yard over traditional fills; however, this cost may be recouped through management fees collected from dredging projects.     

埕岛油田海上石油平台基础冲刷研究

海洋石油平台的建立会改变平台周围的水动力条件，其中平台的基础及与之连接的海底管缆(输油管道、注水管道、海底电缆等)附近产生冲刷现象，对平台和海底管缆的安全造成威胁。根据对研究区典型平台的4次实洲水深并结合以往资料，分析了埕岛油田海上石油平台基础冲刷的过程及其规律。     

Reconstruction of sea surface dimethylsulfide in the North Pacific during 1970s to 2000s

We proposed an empirical equation of sea surface dimethylsulfide (DMS, nM) using sea surface temperature (SST, K), sea surface nitrate (SSN, μM) and latitude (L, °N) to reconstruct the sea surface flux of DMS over the North Pacific between 25°N and 55°N: ln DMS = 0.06346 · SST − 0.1210 · SSN − 14.11 · cos(L) − 6.278 (R² = 0.63, p < 0.0001). Applying our algorithm to climatological hydrographic data in the North Pacific, we reconstructed the climatological distributions of DMS and its flux between 25 °N and 55 °N. DMS generally increased eastward and northward, and DMS in the northeastern region became to 2–5 times as large as that in the southwestern region. DMS in the later half of the year was 2–4 times as large as that in the first half of the year. Moreover, applying our algorithm to hydrographic time series datasets in the western North Pacific from 1971 to 2000, we found that DMS in the last three decades has shown linear increasing trends of 0.03 ± 0.01 nM year^− 1 in the subpolar region, and 0.01 ± 0.001 nM year^− 1 in the subtropical region, indicating that the annual flux of DMS from sea to air has increased by 1.9–4.8 μmol m^− 2 year^− 1. The linear increase was consistent with the annual rate of increase of 1% of the climatological averaged flux in the western North Pacific in the last three decades.     

南海北缘东部盆地油气资源研究

南海北缘东部的珠江口盆地及台西南盆地蕴藏着十分丰富的油气资源，根据区域构造背景、盆地发育分布的特点及中、新生代的油气地质条件，结合含油气构造、油气田、油气井的分布规律，利用油气资源评价的理论、方法，对区内的油气资源进行了综合研究，并按照油气资源状况划分出油气富集区、油气潜力区、油气远景区，在此基础上，再进一步划分出4条油气富集带、11条油气潜力带、8条油气远景带，充分显示了该区石油、天然气的分布规律和油气地质特点，为商业性的勘探开发和理论研究奠定了基础。     

REE distribution in water-sediment interface system at deep ocean floor

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