Showing papers by "Woods Hole Oceanographic Institution published in 1974"

The surface chemistry of hydrous manganese dioxide

Abstract: An experimental investigation has shown that H+ and OH− are potential determining ions for the δMnO2 surface The pH (ZPC) was determined using electrophoretic mobilities and Na+ and K+ adsorption and found to be 225 Alkalimetric titration curves failed to provide a direct determination of the pH (ZPC), however, when combined with the Na+ adsorption data they provide a means for estimating the surface charge Surface charge values of approximately 100 μ C/cm2 were found at pH 8, considerably higher than the charge on SiO2 which has a similar pH (ZPC) Below pH 35 manganese was released to solution and the experimental data suggest that this is due to the reduction of MnO2 δMnO2 is thermodynamically unstable with respect to H2O below that pH

A kinetic approach to the effect of temperature on algal growth1

Abstract: A simple model incorporates the combined effects of temperature and nutrient limitation on the growth rate of algae. The temperature function is described by the Arrhenius equation and the nutrient relationship with the Monod model. The Arrhenius equation is inserted into the Monod model for the maximum growth rate µ, so that the growth rate is described by the product of temperature and nutrient expressions. The utility of the Arrhenius equation in describing the effect of temperature on µ for phytoplankton is tested with data from the literature on continuous culture experiments with freshwater and marine algae; the Arrhenius model describes the relationship between µ and temperature extremely well. Several restrictions to widespread use of the model limit its application to laboratory studies, but its general concepts may apply to natural water situations.

The Galapagos Spreading Centre: Lithospheric Cooling and Hydrothermal Circulation

Abstract: Summary The spatial pattern of cooling near a spreading ridge crest was investigated with a suite of 71 precisely-navigated heat-flow stations on the Galapagos spreading centre, East Pacific, near 86"W longitude. Stations are on crust less than 1.0 My old on which bathymetry and sediment distribution are well known. Values vary from near zero to greater than 30 HFU (10-6 cal cm-2 s-1). The average over the entire region is significantly less than that predicted by theoretical conduction models of a cooling lithosphere. We observe a regular variation of the heat-flow pattern with a wavelength of 6 & 1 km approximately normal to the ridge crest. Heat-flow maxima are characteristically located near faults and local topographic highs. The locations of fields of small sediment mounds, apparently hydrothermal vents, are also restricted to these faulted, elevated areas of high heat flow. Near-axis, bottom water temperature anomalies of several hundredths "C were detected. The low average, the low minima in the heat-flow pattern, and the water temperature anomalies suggest that hydrothermal circulation accounts for approximately 80 per cent of the geothermal heat released near the ridge crest. We conclude that the hydrothermal circulation pattern is controlled by one or more of the following physical properties of the system : highly developed cellular convection, discrete zones of high permeability, variation in the strength of heat sources near the base of the crust, or bottom topography. Our results imply that heat-flow studies near active oceanic ridges will be of most value if they are sufficiently detailed and well navigated to define the systematic small-scale variations that appear to be caused by hydrothermal circulation.

Rotating hydraulics of strait and sill flows

Abstract: Theoretical and laboratory models of certain types of strait and sill flows are discussed Specifically, we consider a two‐layer rotating fluid; the upper layer is at rest and the lower layer flows from one large basin to another via a connecting channel The flow is assumed to be principally in a down‐channel direction The cross‐channel balance is therefore geostrophic and the Bernoulli and potential vorticity equations are simplified We further invoke the usual non‐rotating hydraulic principle of maximum transport in flow over a weir—here the end of the channel—and thereby calculate relations between transport, rotation rate, and upstream interface height One of these relations is tested experimentally with favorable results A nonsteady decaying flow in the same system is analyzed similarly and also compares well with experiment, as does a flow in both layers driven by an initial density imbalance Some connections with oceanic strait and sill flows are discussed

Heat Loss from the Earth: New Estimate

Abstract: The average heat loss from the Earth's interior is calculated from heat-flow values and tectonic models of sea-floor spreading. The value of 10.2 × 1012 cal/s (±1 5 percent) is about 32 percent larger than previous estimates, mainly due to the previously ignored contribution from the cooling lithosphere. The principal uncertainty derives from unknown parameters of the oceanic lithosphere.

Respiration of Benthopelagic Fishes: In situ Measurements at 1230 Meters

Abstract: The respiration rate in situ of two common benthopelagic fishes, Coryphaenoides acrolepis and Eptatretus deani , was monitored at 1230 meters in the San Diego Trough. The respiration rate of C. acrolepis was two orders of magnitude lower and that of E. deani was significantly lower (P

Experimental Bacterial Ecology Studied in Continuous Culture

Abstract: Publisher Summary The chapter focuses on the experimental bacterial ecology studied in continuous culture. The general scope and the selection of details in this chapter attempts to combine the interests of the ecologically oriented microbiologist with those of the environmental biologist. The continuous culture is subdivided into two types: pure culture studies and mixed culture studies. The pure culture studies are subdivided into (a) steady-state kinetics, (b) substrate-limited growth, (c) product-limited growth, (d) multisubstrate-limited growth, (e) multistage culture systems, and (f) temperature-related studies. The steady-state kinetics represented the important step, by which microbial growth kinetics became a most useful tool in studying metabolic, genetic, and ecological phenomena. This chapter discusses the continuous-culture studies with low substrate concentrations and dilution rates concerns the actual ecological situation. With few exceptions, microbial growth and turnover of organic matter in natural environments, or in vivo, proceed at extremely slow rates compared with those obtained in artificial culture media commonly prepared to produce high yields of organisms and/or product. Depending on the growth conditions and the metabolic type of organism studied, the requirements for substrate-limited growth may be difficult to realize experimentally. The chapter also discusses mixed culture studies, such as chemostat enrichments, competition and mutual exclusion, and other types of interaction. The titles of the chapter are not intended to reflect a systematic subdivision of the general topic but it follows a logical order of studies actually done.

Growth of vitamin b12‐requiring marine diatoms in mixed laboratory cultures with vitamin b12‐producing marine bacteria12

Abstract: SUMMARY The vitamin B12 requirement of several marine diatoms can be satisfied in B12−limited laboratory cultures by heterotrophic marine bacteria isolated from the same waters and from sediments. The bacteria can utilize diatom excretory products, or the remains of dead diatom cells, in the production of the vitamin. The growth of 12 B121− requiring diatoms (7 genera) in mixed cultures with 14 different bacteria (without added B12) was compared to the growth of those same diatoms in axenic cultures with excess added B12. Diatom growth was generally rapid in the first few days, followed by sustained, slower growth. The diatom yields in mixed cultures ranged from 0.8 to 84% of the yields in axenic cultures with added B12. In a detailed study of one mixed culture, increases in diatom densities were paralleled by increases in cell densities of the bacterium during the first few days of exponential diatom growth. During the period of slow diatom growth, when diatom densities oscillated but steadily increased, the decreases in diatom densities were associated with increased bacterial growth. This suggests that death of a fraction of the B12-limited diatom population releases sufficient organic matter to stimulate growth of the bacteria and their subsequent excretion of B12; this B12 in turn stimulates further growth of the diatoms. Diatom-bacteria interactions leading to the production of B12 may be important in maintaining viable populations of B12-requiring diatoms in nutrient-poor waters during periods between blooms, when conditions are unfavorable for rapid growth.

New approach to surface seawater palaeotemperatures using 18 O/ 16 O ratios in silica of diatom frustules

Abstract: THE oxygen isotopic composition of calcium carbonate and silica deposited by organisms in water depends on the temperature and the isotopic composition of the water1.

Humic substances from seawater

Abstract: SINCE the first spectroscopic observation of humic substances in seawater1, it has been presumed that they constitute a considerable fraction of the dissolved organic matter in the sea2–4. Base-soluble organics were first isolated from seawater in 1958 (ref. 5), but the chemical composition and source of these materials has remained speculative and controversial3,6–9. We here present evidence that humic substances in the Sargasso Sea display bulk characteristics which differ from those of humics from coastal waters and especially from those of humic substances isolated from soils and marine sediments.

Abyssal Furrows and Hyperbolic Echo Traces on the Bahama Outer Ridge

Abstract: Near-bottom investigations with a deep-towed instrument package show that steep-sided, flat-floored furrows (1 to 100 m wide by 0.5 to 20 m deep) eroded into Holocene and Pleistocene hemipelagic mud are responsible for the characteristic hyperbolic echo traces on surface-ship echograms recorded over the Bahama Outer Ridge (water depth, 4 to 5 km). This echogram character, previously interpreted as being caused by side reflections from depositional wave forms, has been typically recorded in abyssal regions of contour-current activity. It is suggested that these remarkably straight longitudinal furrows are formed by secondary helical circulations in the bottom-boundary mixed layer.

Preliminary Model for Extrusion and Rifting at the Axis of the Mid-Atlantic Ridge, 36°48′ North

Abstract: The inner rift valley of the Mid-Atlantic Ridge at 36°48′ N. is 1.5 to 3 km wide and 100 to 400 m deep. It is symmetrical in profile with a discontinuous medial ridge 100 to 240 m high and 800 to 1,300 m wide along its axis. The medial ridge is replaced every 1 to 3 km with a central trough 200 to 600 m wide. The medial ridge is apparently built by eruptions of pillow basalt recurring at intervals of roughly 14,000 years at a given point. Between eruptions (and possibly during them), the ridge splits and divides along its axis and subsides, which produces the central trough. As the trough widens and deepens, it eventually taps magma in a shallow reservoir, initiating a new eruption that rebuilds the medial ridge. Outward spreading of the inward-dipping shingled halves of the former medial ridge produces a layer of pillowed basalts about 400 m thick (oceanic layer 2A), in which resides the bulk of the remanant magnetization of the ocean floor. This layer overlies a layer of intrusive rock (layer 2B) composed of a dike complex that feeds eruptions building the medial ridge as well as the outward moving, solidified shells of a shallow magma chamber.

Inner floor of the Rift Valley: first submersible study

Abstract: THE Rift Valley of the Mid-Atlantic Ridge1, within which lies a segment of the accreting plate boundary between Africa and North America, is well defined between 36° 40′N and 36° 55′ N. It is about 30 km wide and 1.5 km deep in that area (Fig. 1). This small portion of the rift, WSW of the Azores, was chosen as the primary target of the French–American Mid-Oceanic Undersea Survey (FAMOUS) programme, and many surface ship studies have been conducted already. We report here preliminary results of seven dives into the deepest part of the Rift Valley that were made by the bathyscaphe Archimede during the summer of 1973.

Protein and Carbohydrate Composition of the Cell Envelope of Halobacterium salinarium

Abstract: The isolated cell envelope of Halobacterium salinarium strain 1 contained 15 to 20 proteins that were resolved by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. All but one of these proteins had molecular weights of 130,000 or less and together accounted for 50 to 60% of the total envelope protein. The remaining 40 to 50% of the envelope protein was accounted for by a single protein with an apparent molecular weight of approximately 194,000 that stained for carbohydrate with periodate-Schiff reagent. The proteolytic enzymes trypsin and Pronase were used to show that the carbohydrate is covalently bound to the protein. Separation of amino sugar- and hexose-containing tryptic peptides by gel filtration indicated that all of the nonlipid carbohydrate of the cell envelope is covalently bound to protein. The results of partial purification by phenol extraction indicated that both the amino sugar and hexose are bound to the 194,000-molecular-weight protein. Exposure of isolated cell envelopes to low salt concentration resulted in solubilization of a majority of the envelope proteins. A relatively small number of proteins, including the high-molecular-weight, carbohydrate-containing protein, remained bound to the sedimentable cell membrane fraction.

Factors affecting the sensitivity of Limulus lysate.

Abstract: Limulus lysate clots when mixed with picogram quantities of endotoxins. The sensitivity of the lysate was improved 100-fold by the removal of an inhibitor and addition of divalent cations. The methods developed in this investigation eliminated much of the seasonable variability of the lysate, improved the heat stability after lyophilization, and made it possible to use the lysate with saline solutions.

The Galapagos Spreading Centre: Heat-flow low on the North Flank

Abstract: Summary The axis of the Galapagos spreading centre has a high but variable heat flow. A distinct local minimum in the heat-flow field exists in a region 4–6 My old on the northern flank of the spreading centre. This minimum is unlikely to have been produced from refraction of heat flux due to either topographic and sediment thickness irregularities or to the transient effect of sediment loading. We suggest that the oceanic crust has an ‘effective’ permeability to fluid flow and that hydrothermal circulation causes much of the heat loss to arise through mass transport. This mechanism also lowers the conductive heat flow from beneath the sediments causing a regional minimum in the observed heat flux. We consider two different models for the control of the ‘effective’ permeability. The first invokes chemical reactions to open and close the cracks which give rise to the ‘effective’ permeability. In the second, no reactions are invoked and the oceanic crust never completely loses its permeability. The latter model implies that in areas of rough topography with outcropping basement highs the regional heat flow cannot be determined solely by conductive measurements.

Shallow Structure of the New Hebrides Island Arc

Abstract: Marine geological and geophysical studies of the New Hebrides island arc have been made to study (a) the present development of lithospheric plate boundaries, (b) evidence for creation of oceanic crust behind the frontal arc in interarc basins, and (c) evidence for reversal of the arc from east-facing to the present-day west-facing orientation. The arc system is bisected between 13° and 15° S. by the east-west Hazel Holme Fracture Zone which connects the trench and a north-south—trending spreading center (Nova Rise) on the Fiji Plateau near 174° E. The crust on the plateau south of the fracture zone is very young. Narrow interarc basins are present but youthful, south of about 18° S. North of the Hazel Holme Fracture Zone, interarc basins are less well developed and apparently even younger. Most of the Fiji Plateau has apparently been formed by spreading from the Nova Rise rather than within interarc basins associated with the New Hebrides. The tectonics of the central region of the arc system, immediately south of 15° S., appears to be governed by the transform section of the Hazel Holme Fracture Zone and by subduction of the D9Entrecasteaux Fracture Zone into the trench rather than by interarc spreading. In this region, the western and eastern chains of the New Hebrides group have been recently uplifted and tilted toward one another, creating a sedimentary basin. Most data do not support the idea that the eastern island belt in this region, including Maewo and Pentecost islands, is an ancient remnant of an east-facing arc system. These islands have been uplifted only very recently and later than the western islands. Therefore, any east-facing subduction phase must have ceased recently and occurred after subduction beneath the western islands. We suggest instead that the eastern island belt represents an interarc basin floor or a frontal arc uplifted behind the volcanic line.

Salt fingers observed in the mediterranean outflow.

Abstract: Salt fingers, convection cells which constitute a possible mixing mechanism of the ocean, have now been observed in the Mediterranean outflow. The fingers, 6 millimeters in diamneter and 24 centimeters long, were photographed below the salinity maximum of the outflow, in an interface 22 centimeters thick where temperature and salinity decreased O. 15°C and 0.03 per mil, respectively.

Atmospheric carbon dioxide levels as indicated by the stable isotope record in wood

Abstract: THE concentration of CO2 in the atmosphere has increased from about 290 parts per million (ppm) by volume in 1900 (ref 1) to 323 ppm in 1972 (ref 2) and this increase is generally held to be due chiefly to combustion of fossil fuels Indeed by 1970 this artificial mechanism had introduced to the atmosphere an amount of CO2 equivalent to 22% of the natural or pre-industrial atmospheric inventory3 About half of the added CO2 seems to have been transferred to the other major reservoirs of the dynamic carbon cycle, the oceans and biosphere Before examining the threat to global climate and marine life4, future CO2 levels from this source must be predicted Before such extrapolations can be confidently applied, however, we must fully understand the past response of the atmosphere to fossil CO2 emission Since direct measurements of atmospheric CO2 are either not available or considered unreliable indirect methods of assessing the CO2 buildup must be invoked Here a novel and potentially valuable approach is presented

Counter-clockwise motion of paleomagnetic directions 24000 years ago at Mono Lake, California.

Abstract: Paleomagnetic directions from two sites at Mono Lake, California, 24000 years ago traced-out a well-defined counter-clockwise loop 25° in diameter. Major features of the loop can be explained by an inward directed radial dipole located at 0.5 Earth's radius, drifting eastward along a path 15° south of Mono Lake. Its longitudinal velocity was 0.10-0.19°/yr and its strength was 0.12-0.21 relative to the Earth's main dipole moment. The life-span of this perturbing source probably was similar to the period of the magnetic loop, about 850 years.

A precision CTD microprofiler

Abstract: This paper describes a conductivity-temperature-depth (CTD) system designed for precise fine scale measurements of salinity and temperature in the deep ocean. The conductivity sensor is a miniature (8 mm long, 2 mm I.D.) four electrode cell. Temperature is sensed with a combination of a miniature fast thermistor (30 ms) and a platinum resistance thermometer. The combined outputs of the thermistor and the platinum thermometer, with their respective interface circuits, have the excellent long term stability and linearity of the platinum thermometer and the speed of the thermistor but are unaffected by thermistor calibration drift. Pressure is measured using a strain gage bridge transducer. All three sensors with their respective interface circuits and the 16 bit digitizer are excited with 10 KHz sine waves. The D/A converter in the digitizer is an electronically switched binary ratio transformer having negligible errors. The digitizer uses successive approximation to measure the 10 KHz sensor output to input voltage ratio. Digitization time is 10 milliseconds, thus, a complete scan of all three sensors is made in 30 milliseconds. The digital output of each scan is transmitted via armoured cable to the shipboard unit in "TELETYPE" format using frequency-shift-key (FSK) modulation. The shipboard unit demodulates the FSK signal from the sensor unit and provides both serial and parallel digital outputs to a shipboard computer. Digital displays and analog outputs are also provided by the deck unit.