Solubility of oxygen in the major sea salts as a function of concentration and temperature     

Frank J. Millero  Fen Huang  Arthur L. Laferiere 《Marine Chemistry》2002,78(4):125

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A deep towed explosive source for seismic experiments on the ocean floor     

Donald E. Koelsch  Warren E. Witzell Sr.  James E. Broda  Frank B. Wooding  G. M. Purdy 《Marine Geophysical Researches》1986,8(4):345-361

A new seismic source for carrying out high resolution measurements of deep ocean crustal structure has been constructed and successfully used in a number of ocean bottom refraction experiments on the Mid Atlantic Ridge near 23° N. The source is towed within 100 m of the ocean floor on a conventional 0.68 coaxial cable and is capable of firing, upon command from the research vessel, up to 48 individual 2.3 kg explosive charges. The explosive used was commercially available Penta-Erythritol-Tetra Nitrate (PETN) that was activated by 14.9 gm m^–1 Primacord and DuPont E-97 electrical detonators. For safety reasons each detonator was fitted with a pressure switch that maintained a short until the source was at depth in excess of approximately 300 m. In addition, a mechanical protector isolated the detonator from the main charge and was only removed by the physical release of the explosive from the source package. These and other safety precautions resulted in several misfires but three experiments were successfully completed during the summer of 1985 at source depths of 3000–4000 m.  相似文献   

A comparative analysis of recruitment variability in North Atlantic flatfishes — testing the species range hypothesis     

William C. Leggett  Kenneth T. Frank 《Journal of Sea Research》1997,37(3-4)

The hypothesis that recruitment variation in flatfishes should be most variable at the northern edge of the species range, least near the centre of the range, and intermediate near the southern limit was tested using stock and recruitment data generated from sequential population analysis for several different flatfish stocks involving four species (plaice Pleuronectes platessa, sole Solea vulgaris from the eastern Atlantic, American plaice Hippoglossoides platessoides, and yellowtail flounder Limanda ferruginae from the western Atlantic). Several groundfish species have been found to conform to this so-called species range hypothesis with the suggestion that density-independent processes predominate at the edges of the distributional range and density-dependent processes dominate in the centre of the range. Our results were generally inconsistent with the hypothesis: the coefficient of variation (CV) of recruitment for plaice in the eastern Atlantic was independent of latitude, the CV of recruitment for sole exhibited a dome-shaped relationship with latitude with the highest CVs occurring at the mid-point of the range, and the CV of recruitment for the western Atlantic stocks exhibited a monotonic decrease with latitude. We extended our latitudinal analyses by assessing both the degree of dependency of recruitment on spawning stock biomass and the spatial and temporal scales of variability in recruitment and pre-recruit survival for the eastern Atlantic stocks. In general our analysis revealed no evidence of a strong stock and recruitment relationship for any of the stocks examined, and previously published analyses revealed no such patterns with latitude. Analysis of both de-trended recruitment and pre-recruit survival time series over the species ranges of sole and plaice revealed strong positive correlations among adjacent stocks and inverse correlations among stocks at the extremes of the range. Recruitment variation in the flatfish stocks examined appears to be dominated by density-independent factors, operating at a local scale, on the egg and larval stages.  相似文献   

Persistently declining oxygen levels in the interior waters of the eastern subarctic Pacific     

Frank A. Whitney  Howard J. Freeland  Marie Robert 《Progress in Oceanography》2007,75(2):179-199

Fifty years of measurements at Ocean Station Papa (OSP, 50°N, 145°W) show trends in the interior waters of the subarctic Pacific that are both impacted by short term (few years to bi-decadal) atmospheric or ocean circulation oscillations and by persistent climate trends. Between 1956 and 2006, waters below the ocean mixed layer to a depth of at least 1000 m have been warming and losing oxygen. On density surfaces found in the depth range 100-400 m (σ_θ = 26.3-27.0), the ocean is warming at 0.005-0.012 °C y⁻¹, whereas oxygen is declining at 0.39-0.70 μmol kg⁻¹ y⁻¹ or at an integrated rate of 123 mmol m⁻² y⁻¹ (decrease of 22% over 50 years). During this time, the hypoxic boundary (defined as 60 μmol O₂ kg⁻¹) has shoaled from ∼400 to 300 m. In the Alaska Gyre, the 26.2 isopycnal occasionally ventilates, whereas at OSP 26.0σ_θ has not been seen at the ocean surface since 1971 as the upper ocean continues to stratify. To interpret the 50 year record at OSP, the isopycnal transport of oxygenated waters within the interior of the subarctic Pacific is assessed by using a slightly modified “NO” parameter [Broecker, W., 1974. “NO” a conservative water-mass tracer. Earth and Planetary Science Letters 23, 100-107]. The highest nitrate-oxygen signature in interior waters of the North Pacific is found in the Bering Sea Gyre, Western Subarctic Gyre and East Kamchatka Current region as a consequence of winter mixing to the ∼26.6 isopycnal. By mixing with low NO waters found in the subtropics and Okhotsk Sea, this signature is diluted as waters flow eastward across the Pacific. Evidence of low NO waters flowing north from California is seen along the coasts of British Columbia and SE Alaska. Oxygen in the subsurface waters of the Alaskan Gyre was supplied ∼60% by subarctic and 40% by subtropical waters during WOCE surveys, whereas such estimates are shown to periodically vary by 20% at OSP. Other features discernable in the OSP data include periods of increased ventilation of deeper isopycnals on an ∼18 year cycle and strong, short term (few month) variability caused by passing mesoscale eddies. The potential impacts of declining oxygen on coastal ecosystems are discussed.  相似文献   

Depositional history of the Helgoland mud area,German Bight,North Sea   总被引：1，自引：0，他引：1  

Dierk?HebbelnEmail author  Carolyn?Scheurle  Frank?Lamy 《Geo-Marine Letters》2003,23(2):81-90

The Helgoland mud area in the German Bight is one of the very few sediment depocenters in the North Sea. Despite the shallowness of the setting (<30 m water depth), its topmost sediments provide a continuous and high-resolution record allowing the reconstruction of regional paleoenvironmental conditions for the time since ~400 a.d. The record reveals a marked shift in sedimentation around 1250 a.d., when average sedimentation rates drop from >13 to ~1.6 mm/year. Among a number of major environmental changes in this region during the Middle Ages, the disintegration of the island of Helgoland appears to be the most likely factor which caused the very high sedimentation rates prior to 1250 a.d. According to historical maps, Helgoland used to be substantially bigger at around 800 a.d. than today. After the shift in sedimentation, a continuous and highly resolved paleoenvironmental record reflects natural events, such as regional storm-flood activity, as well as human impacts at work at local to global scales, on sedimentation in the Helgoland mud area.  相似文献   

The distribution of geothermal fields along the East Pacific Rise from 13°10′ N to 8°20′ N: Implications for deep seated origins     

Kathleen Crane  Frank Aikman III  Jean-Paul Foucher 《Marine Geophysical Researches》1988,9(3):211-236

In 1983 a combined SeaMARC I, Sea Beam swath mapping expedition traversed the East Pacific Rise from 13°20 N to 9°50 N, including most of the Clipperton Transform Fault at 10°15 N, and a chain of seamounts at 9°50 N which runs obliquely to both the ridge axis and transform fault trends. We collected temperature, salinity and magnetic data along the same track. These data, combined with Deep-Tow data and French hydrocasts, are used to construct a thermal section of the rise axis from 13°10 N to 8°20 N.Thermal data collected out to 25 km from the rise axis and along the Clipperton Transform Fault indicate that temperatures above the rise axis are uniformly warmer by 0.065°C than bottom water temperatures at equal depths off the axis. The rise axis thermal structure is punctuated by four distinct thermal fields with an average spacing of 155 km. All four of these fields are located on morphologic highs. Three fields are characterized by lenses of warmed water 20 km in length and 300 m thick. Additional clues to hydrothermal activity are provided in two cases by high concentrations of CH₄, dissolved Mn and ³He in the water column and in another case by concentrations of benthic animals commonly associated with hydrothermal regions.We use three methods to estimate large-scale heat loss. Heat flow estimates range from 1250 MW to 5600 MW for one thermal field 25 km in length. Total convective heat loss for the four major fields is estimated to lie between 2100 MW and 9450 MW. If we add the amount of heat it takes to warm the rest of the rise axis (489 km in length) by 0.065.°C, then the calculated axial heat loss is from 12,275 to 38,525 MW (19–61% of the total heat theoretically emitted from crust between 0 and 1 m.y. in age).  相似文献   

Marine systems: moving into the genomics era     

Karen Wilson  Michael Thorndyke  Frank Nilsen  Alex Rogers  & Pedro Martinez 《Marine Ecology》2005,26(1):3-16

The study of biological systems has been revolutionized by the use of genomic technologies. Most of the knowledge gathered over the last few years refers to terrestrial models. The study of marine systems using genomic technologies has, apart from a focus on microbial systems, been generally neglected although there are signs that this situation may be changing. This review analyses recent progress made in the field of marine genomics and identifies the broad areas in which this new technology is having the greatest impacts. These studies include comparative, functional and environmental genomics of metazoan animals. In many cases, as well as benefiting marine science, studies on marine taxa are having wide‐ranging impacts on our global understanding of genomes and genomics.  相似文献   

MKIIIB-CTD: improving its system output     

Thomas J. Mller  Jürgen Holfort  Frank Delahoyde  Robert Williams 《Deep Sea Research Part I: Oceanographic Research Papers》1995,42(11-12)

In the Neil Brown Instruments' MKIIIB-CTD (conductivity-temperature-depth profiler), the system's digital outputs for the three basic measurements of temperature, conductivity and pressure typically show some small amplitude deviations from smooth calibrations which should be corrected for to achieve high accuracies, as required, e.g. within the Hydrographic Program (WHP) of the current World Ocean Circulation Experiment (WOCE). These deviations show up as (i) a strong nonlinearity or even discontinuity of several mK close to 0°C in temperature output leading to too high subzero temperatures; (ii) a jump of order 0.002 mS cm⁻¹ in conductivity output when passing the half-range value 32.768 mS cm⁻¹, which causes jumps in the relation of potential temperature and salinity; and (iii) errors in pressure measurements of up to 4 dbar due to mechanical hysteresis and both static and dynamic responses to temperature changes. The existence of these effects is demonstrated, and methods to reduce the associated errors are suggested.  相似文献   

Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach   总被引：3，自引：0，他引：3  

Jef Guelinckx  Joachim Maes  Loreto De Brabandere  Frank Dehairs  Frans Ollevier 《Estuarine, Coastal and Shelf Science》2006,66(3-4):612-623

Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this, stomach contents were used to verify the isotopic differences between the food sources at the sampling stations. From May 2000 to April 2001 fish were collected monthly in the upper and lower estuary. Muscle tissue and stomach contents were analyzed for δ¹³C and δ¹⁵N using an EA-IRMS. Based on the stomach contents, it was demonstrated that δ¹⁵N could not be used as a tracer for fish migration because the longitudinal estuarine δ¹⁵N gradient had reversed completely during autumn. The δ¹³C gradient, however, was found to be reliable for studying fish movement in the Schelde estuary.Seasonal movements of clupeoids in the Schelde estuary were analyzed by separating the temporal abundance patterns into migration groups based on their muscle isotopic composition. Immigration and emigration seem to occur continuously throughout the year. Most exchange occurred in November. During winter, immigration remained high but gradually decreased. Although the herring and sprat abundance further declined in the estuary during February and March, large seaward emigration was not fully demonstrated. As temporal overlap between immigration and emigration is concluded the results support the hypothesis that migration to estuarine nurseries is individually based.  相似文献   

Underwater inspection/testing/ monitoring of offshore structures     

R. Frank Busby 《Ocean Engineering》1979,6(4):355-491

The extraction of offshore oil and gas deposits has resulted in installation of massive steel and concrete platforms in progressively deeper and more hostile waters. Concern for the safety of platform personnel, potential damage to the environment, and the assurance of profitable, unimpeded, extraction of these offshore resources is a concern of host-country governments and the offshore operators.Requirements for underwater inspection of these structures and the techniques and tools to conduct such inspection vary widely from country-to-country. In some instances periodic inspection is required by law; in other instances there is no requirement whatever once the structure has been installed. The instruments to conduct underwater inspections also vary; their effectiveness is sometimes questionable, and the cost of underwater inspection to the operator (which will eventually be borne by the consumer) is high and will get higher as the water depth and complexity of the structure increases.The purpose of this six month study was: 1) to identify and describe all actual or potential underwater inspection requirements (national and international) for fixed concrete and steel structures promulgated by the governments of offshore oil and gas producing countries and by the offshore operators themselves; 2) to identify and assess the state-of-the-art in underwater non-destructive testing/monitoring/inspection of offshore structures; 3) to evaluate the capability of servicing and hardware producers to meet the inspection requirements identified; and 4) to describe and establish priorities for specific tasks for technology development that should be undertaken to satisfy current and future requirements. While this study concentrates on fixed offshore oil and gas structures, the results also reflect the state-of-the-art in underwater inspection/testing for other offshore structures as well, e.g., floating power platforms; offshore terminals and deepwater ports.The data for this study were collected in three stages. First, an intensive literature review was conducted to initially identify those organizations and governments active in projects related to the study goals (the results of this literature survey are presented in Appendix I). Second, telephone interviews were conducted to further identify “Requirements” sources and suppliers/manufacturers of inspection/testing capabilities in the U.S. and Europe. Third, personal interviews were conducted with individuals active in hardware production or inspection services. Personnel and organizations contacted (both by telephone and on a personal basis) are identified in Appendix II (Requirements) and III (Capabilities), respectively. Approximately four months were required to satisfy the data collection phase; the remaining two months were spent analyzing, reducing and synthesizing the data obtained.  相似文献