Sargasso Sea Water Research Articles

Structural studies on marine humus: a new reduction sequence for carbon skeleton determination

A new reduction sequence designed to transform polyfunctional molecules to hydrocarbons is applied to fulvic acid isolated from Sargasso Sea and coastal water. Following methylation, samples are reduced by high-pressure hydrogenation. These products are treated with dibromotriphenylphosphorane to brominate alcohols and phenols and to cleave ether linkages. Finally, the brominated products are reduced by low pressure hydrogenation and hydrocarbons are isolated by liquid-solid chromatography. The hydrocarbons produced indicate that marine lipids are important structural components and that terrestrial sources are minor, even in coastal samples. Also, an unusual series of aromatic structures was obtained, the source of these is unknown.

Observational Evidence for Transformation of Tropospheric Waters within Cyclonic Rings

Abstract The North American Slope and Gulf Stream components that constitute the initial water masses within a cyclonic ring can combine with Sargasso Sea water to generate Western North Atlantic Water (WNAW) common to the main anticyclonic gyre in the Sargasso Sea. Evidence from the 1967 ring survey indicates that warm, saline water from above mixes with cooler, fresher water from below to produce WNAW in the region of the mid-thermocline (7–12°C). At mid-thermocline depths, WNAW can be traced along σt surfaces from the ring center to the Sargasso Sea. Vertical stability conditions support the mixing concept. Distributions of the zooplankton species Nematoscelis megalops found for the 1975–76 Ring D survey can be interpreted as indicating mixing and detrainment through the mid-thermocline region.

The cycling of biogenic compounds and their diagenetically transformed products in seawater

Results are presented for two studies concerned with the sources, transport and transformation mechanisms of two classes of organic compounds. An emphasis is placed on the importance of collecting and correlating related chemical and oceanographic data with the qualitative and quantitative organic compound analyses. The first study involves the analysis of seawater samples for a class of relatively labile, biogenic compounds, the sterols. From the vertical profiles of the sterols, along with hydrographic, particulate organic carbon, and total particulate matter data, an attempt is made to understand sterol distributions in the ocean and the transport mechanisms governing their movement into the deep sea. The second study involves the analysis of Sargasso Sea water samples for a class of more resistant, transformed biogenic compounds, humic and fulvic acids. Their isolation, structural elucidation, mechanism of formation and fate are discussed.

Manganese in seawater and the marine manganese balance

Abstract Surface water samples from the Sargasso Sea, the western North Atlantic, and the northeast Pacific all have manganese concentrations of about 0.1 ppb. Sargasso Sea and northeast Pacific deep water samples have about one-fourth those concentrations; concentrations in the North Atlantic western boundary current appear intermediate. The data suggest that manganese is removed from seawater more rapidly than the general oceanic turnover time of about 1,500 years. Downward transport of manganese in downwelling surface water and falling biogenic debris can supply only a few per cent of the total amount accumulating in pelagic sediments, although it can supply all the manganese accumulating in ferromanganese crusts and nodules. A Sargasso Sea and a northeast Pacific profile show no indication of a deep water manganese maximum, suggesting that submarine volcanism and hydrothermal input is not a major source of manganese to either deep ocean water or normal pelagic sediments. Because the sedimentary manganese is supplied neither by dissolved manganese in seawater nor by hydrothermal inputs, we conclude that the ‘excess’ manganese in pelagic sediments comes from terrigenous particles.

Alkali and alkaline earth metal chemistry of marine aerosols generated in the laboratory with natural sea waters

Atmospheric sea salt particles, produced in the laboratory by bubbles bursting at the surface of natural seawater solutions, were examined for their alkali and alkaline earth metal content in several particle size categories. No enrichments of K, Ca and Mg relative to the seawater source were found in these atmospheric particles using 1. (1) Sargasso seawater or Narragansett Bay seawater. 2. (2) filtered seawater or unaltered seawater. 3. (3) two different bubble path lengths. Only with the addition of natural surfactants was any enrichment over the seawater ratio found in these aerosols. In this case, K and Mg may have been enriched on the smallest particles. Calculations, indicate that the organic carbon content of aerosols produced from even highly productive natural seawaters cannot account for apparent enrichments of K observed in the environment. These experiments suggest that enrichment of alkali and alkaline earth metals in sea salt particles produced from most natural seawaters is environmentally insignificant.

Factors influencing the organic carbon content of marine aerosols: A laboratory study

Summary and entire article are available on microfiche. Order from American Geophysical Union, 1909 K Street, N. W., Washington, D. C. 20006. Document J76-004; $1.00. Payment must accompany order. A series of laboratory experiments using natural seawater were conducted to examine several factors which influence the organic carbon(OC) content of marine atmospheric sea-salt particles produced by bursting bubbles at the air-sea interface. The organic carbon/Na ratio of these laboratory-generated atmospheric sea-salt particles was found to be dependent on the quantity of organic carbon in the seawater, the nature of the organic compounds in the seawater, the amount of surfactants in the seawater, and the distance the bubbles traveled in seawater before bursting at the air-seawater interface. The dissolved and/or colloidal fractions of the organic material in the seawater used were primarily responsible for the organic carbon content of the atmospheric particles. Filtration of the seawater did not affect the OC/Na ratio of the aerosols produced. The OC/Na ratio of atmospheric sea-salt particles generated from Sargasso seawater was 0.008±0.005, while that of particles generated from Narragansett Bay water was 0.093±0.053.

Long-range acoustic propagation through the Gulf Stream

Acoustic charges were detonated on a line normal to the Gulf Stream and recorded near Bermuda. Received signals were analyzed in one-third-octave bands from 40 to 200 Hz and analyzed for rms value over an 8-sec period. Results indicate areas of low transmission associated with the North and South Walls of the stream that ranged between 4–10 dB. Highest levels were received from charges detonated north of the stream. These results can possibly be explained by varying sonic-layer depths and a deepening sound channel axis between Slope Water and deep warm layers of Sargasso Sea water. Other factors possibly related to received amplitude fluctuation may be internal waves and ’’patches’’ of water different from surrounding areas. Further experiments using cw sounds are being planned to delineate seasonal and angular factors. Subject Classification: [43]30.20, [43]30.25.

Observed decay of a cyclonic Gulf Stream ring

A cyclonic Gulf Stream ring was tracked in the western Sargasso Sea from March 1971 to April 1972. It moved 700 km southwest at 2 km day −1 and coalesced with the Gulf Stream off Cape Canaveral. During the first eight months the ring was in relatively deep water and available potential energy relative to 1000 m decayed at an estimated linear rate of 10 21ergs day −1. The ring had a life expectancy of approximately 2–5 years. During the final three months it moved into shallower water and the decay rate accelerated more than fourfold. Layers of Sargasso Sea water inside the ring indicated mixing with surrounding water that may be the decay mechanism of the ring.

Reactions which remove dissolved alumina from seawater

Dissolved alumina can coprecipitate with dissolved silica from seawater enriched with both compounds. This coprecipitation is almost complete within 1h and maintains the concentration of dissolved alumina near naturally occurring oceanic concentrations, well below the alumina concentration of 0.50 ppm A1 found to be stable in filtered Sargasso seawater at 2°C. Only 0.5 ppm Si is necessary to initiate this coprecipitation, which indicates that the concentrations of dissolved alumina that occur in seawater and in interstitial water are a function of the concentration of dissolved silica as well as of the alumina solubility. Dissolved alumina is also quickly removed by solid amorphous silica from solutions of seawater enriched in dissolved alumina and also by several marine sediments in contact with the solution. This process may be an important factor in authigenic mineral formation in marine sediments.

The speciation of arsenic and the content of germanium and mercury in members of the pelagic Sargassum community

Pelagic Sargassum weed and some of its associated fauna were analyzed for the concentration and chemical speciation of arsenic and the content of germanium and mercury. On the average, the distribution of arsenic species in members of the Sargassum community (ppm level) is the same as it is in ‘surface’ Sargasso Sea water (ppb level); 15% As(III), 85% As(V), 1% alkyl-As. Observations suggest that the alkyl-arsenic fraction is generated in situ. The barnacles and shrimp analyzed showed notably higher Ge and Hg content than did other members of the community.

Formation and collapse of surface films

Films that accumulate from lake water, coastal seawater, and Sargasso Sea water with low concentrations of added protein can collapse when subjected to increased surface pressure. Collapse is accompanied by the transformation of some film organic material to particulate material that cannot spread at the interface; these particles are formed from filter‐passing organic material previously in the bulk liquid. Film collapse and accompanying particle formation in nature may be a part of a process that, in some areas, removes filter‐passing surface‐active material from water and precipitates it as particles back into the water column. Such particles tend to sink and could provide particulate food to organisms in the surface waters and perhaps at greater depths.

Small-scale dissolved oxygen variations and the dynamics of Gulf Stream eddies

Small-scale structure in continuous profiles of dissolved oxygen is interpreted in terms of the dynamics of cyclonic Gulf Stream eddies. The data are consistent with theoretical models. The small-scale layers evidenced by the oxygen structure may arise from diffusive overturning when the Prandtl number based on turbulent mixing coefficients is greater than about 7. Under these conditions, Sargasso Sea Water is entrained and then advected radially toward the core of the eddy, causing it to release energy and spin down. Estimates for the values of lateral mixing coefficients lead to A = 10 4 cm 2 s −1 for momentum, and K = 10 3 cm 2 s −1 for density. Some evidence is presented for a mean southwestward advection of the 18° Water in the upper 500 m of the western Sargasso Sea, leading to a possible explanation for the observed southwestward translation of the eddies.

Dissolved oxygen as evidence for 18°C Sargasso Sea Water in the eastern Caribbean Sea

Dissolved oxygen measurements at a serial hydrographic station in the eastern Caribbean and along a hydrographic transect between La Parguera, Puerto Rico and La Guaira, Venezuela (67°W) indicate an intermediate oxygen maximum at about 300 m in the north gradually rising to 175 m in the south. The water at the oxygen maximum has a temperature of about 18°C and a salinity of about 36·5 0 00 , indicating it is 18° Sargasso Sea Water.

Decomposition of marine copepods1

Killed copepods decomposed within 11 days in 4°C Halifax water and within 3 days in 22°C Sargasso Sea water. In both cases initial infection occurred on the exoskeleton and apparently progressed into the organisms through the mouth. The urosome and internal extremities were the last to be attacked.Collection of surface corpses by net is thought to be impossible after the first day of death in subtropical waters and beyond the sixth day in temperate coastal waters.

Bacterial reduction of arsenate in sea water.

ARSENIC in the ocean exists primarily as arsenite and arsenate and thermodynamic calculations1 indicate that in oxygenated sea water at pH 8.1, the equilibrium ratio of the activity of arsenate to arsenite should be about 1026. But observations2–4 suggest that the ratio is, in fact, in the range 10−1 to 101, far from the equilibrum value. My experiments with the inorganic oxidation of added sodium arsenite in surface Sargasso Sea water (in preparation) suggest that, at natural concentrations, all arsenite should be oxidized to arsenate in a matter of weeks or months. The fact that significant quantities of arsenite have been found in all oceanic regions examined is therefore puzzling unless some steady state mechanism can be discovered to account for it.

A THEORETICAL MODEL OF LIGHT SCATTERING BY SARGASSO SEA PARTICULATES1

Mie light‐scattering theory is applied to particles suspended in Sargasso Sea water to estimate their refractive index. The average index m* = 1.05−0.01i relative to water, when combined with a size distribution consistent with observation, reproduces the experimental volume‐scattering function at 632.8 nm with an average error of about 20%. A simple two species model is developed to demonstrate that the above index implies a significant portion of the suspended particulates is organic in nature.

THE DISTRIBUTION OF UREA IN COASTAL AND OCEANIC WATERS1

The distribution of urea has been determined for certain coastal and oceanic waters. The presence of urea‐nitrogen in surface waters off the continental shelf between Panama and Callao, Peru, was extremely patchy and varied in concentration from 0.54–5.00 µg‐atom urea‐N/liter. The higher values were generally from samples collected within a foam slick or windrow. Surface waters in nonupwelling waters north of Callao, Peru, averaged 1.83 µg‐atom urea‐N/liter while surface waters in upwelling waters south of Callao averaged 3.46. Along the continental shelf of the northeast United States between Cape Cod and Cape May, the concentration of urea ranged from 0.25 µg‐atom urea‐N/liter on the 1,000‐fathom (1,830 m) line to a high of 11.20 within New York Harbor. The vertical distribution of urea in Peruvian waters, waters along the northeast United States, as well as Sargasso Sea waters showed considerable fluctuations with depth but there were indications of peaks. The data support the suggestion that urea may serve as an available source of nitrogen for phytoplankton growth.

NUTRIENT‐DENSITY RELATIONSHIPS IN THE WESTERN NORTH ATLANTIC BETWEEN CAPE LOOKOUT AND BERMUDA1

A study of the nutrient‐density relationships of Sargasso Sea water reveals a close correlation; Gulf Stream waters are anomalously higher and more variable in nutrients for a given density. Nutrient anomalies can be used in the same way as oxygen anomalies to map the distribution of Caribbean water in sections across the Gulf Stream. They show that contributions of Caribbean water to the Gulf Stream vary greatly from time to time. Oxidative ratios of ΔO : ΔN : ΔP = (−233) : 16.3 : 1.0 were derived from the correlation between oxygen anomalies and nutrients anomalies of Gulf Stream water in the sigma‐t range 25.0–26.8.

Scattering of light by Sargasso Sea water

This experimental investigation deals with the problem of the scatterance of light by very clear ocean water. The forward scatterance was measured close to a laser beam using a new measuring device. The forward particle scatterance was found to be virtually independent of wavelength, whereas the backward scatterance was dependent on the wavelength. The water investigated has a high degree of clearness compared with other areas. The ratio of scatterance at 45° to total scatterance over all angles was found to vary within narrow limits for different oceanic areas.

Strontium Content and Variable Strontium-Chlorinity Relationship of Sargasso Sea Water

Sargasso Sea water has a variable strontium-chlorinity relationship. This observation is contrary to the view that strontium in the ocean is in constant proportion to chlorinity. It is suggested that the increase in strontium concentration at 500 to 800 meters in Sargasso Sea water results from interaction between organic aggregates and the water.