Estimation of the oxygen and CO2 mean exchange between the ocean and the atmosphere in key areas of the ocean

Current estimations of gas exchange between the ocean and the atmosphere are based on the concepts about diffusive gas transfer across the interface and about a stationary character of the processes; however, under a strong wind, these concepts are invalid. Transfer equations for gas constitutents of the air are incorporated into a numerical model of a nonstationary upper layer of the ocean. These equations contain the source function—gas transfer by bubbles, which becomes noticeable even at a wind speed of 8–10 m/s. The fluxes of oxygen and CO₂ are calculated at a specified wind speed, dependences of these fluxes on the wind speed are constructed, and estimates for the average annual fluxes are obtained for several areas of the Gulf Stream and Kuroshio. A substantial change in the difference of the air-water gas contents under a strong wind, caused by the turbulent exchange growth and appreciably affecting the gas exchange, is noted. The influence of the carbonate system of seawater on the CO₂ transfer during a storm is estimated. The results obtained are compared to the estimates based on the traditional approach.     

Seasonal variations in river discharge and nutrient export to a Northeastern Pacific estuary

Seasonal variations in dissolved nitrogen and silica loadings were related to seasonal variability in river discharge. Dissolved nutrient concentrations measured weekly at three stations in the Yaquina River, Oregon from 1999 through 2001, and then monthly in 2002 were used as the basis for developing a nutrient loading regression as part of a larger agency program for evaluating nutrient processes. Because realistic models of nutrient transport require dense data sets to capture both long and short term fluctuations in nutrient concentrations, data at one freshwater station also were collected hourly for the same years using an in-stream monitor.The effects of storm events on dissolved nutrient transport were examined during three storms, including one in a high rainfall-discharge year, and two in average years, one of which followed a drought year. During the drought year (WY2001), total dissolved nitrate input was considerably less than in wetter years. Dissolved nitrate concentrations, however, were unusually high in the first winter storm runoff after the drought. The freshwater dissolved nitrate nitrogen loads varied from 40,380 kg day⁻¹ during a high-flow storm event to 0.11 kg day⁻¹ during late summer, low flow conditions. Dissolved silica dynamics differed from those of nitrate because during storm events, silica concentrations in the Yaquina River decreased to near zero at the storm height, probably due to dilution by near surface or overland flow, and later recovered.During the time interval studied, over 94% of the dissolved nitrate and silica were transported from the watershed during the winter months of greater rainfall, indicating that seasonality and river flow are primary factors when considering nutrient loadings from this watershed system.     

A low level supplementary heating system for free divers

A simple and effective method of heating divers in extreme cold water has been developed. The local heating concept utilizes a uniformly distributed granular mixture of magnesium and iron particles packed in small sachets. Upon activation by sea water, the two metal mixture behaves as a multitude of short-circuited electrolytic cells, producing thermal energy rather than electrical energy. The 45 mm-square sachets may be placed where heating is required on the diver's body, thus giving rise to the term “local heating”, obviously, the heating system requires no pumping device, or distribution network. Heating rate and duration of output of the sachets are controlled by particle size, and mixture ratio of the constituent Mg and Fe particles.This paper described the development, testing and performance of the heating sachets. Results of live tests in different dive situations are also presented and discussed.     

Current-influenced depositional provinces, continental margin off Cape Hatteras, identified by petrologic method

Analyses of DSRV “Alvin” core samples on the Cape Hatteras margin indicate major textural and compositional changes at depths of about 1000 and well below 2500 m. The distribution patterns of petrologic parameters correlate well with water mass flow and suspended-sediment plumes measured on this margin by other workers. Our study also shows: (a) vigorous erosion and sediment transport at depths of less than 400 m resulting from the NE-trending Gulf Stream flow; (b) deposition, largely planktonic-rich sediment released from the Gulf Stream, on the upper- to mid-slope, to depths of about 800–1200 m; (c) winnowing, resuspension and deposition induced by periodically intensified slope currents on the mid-slope to uppermost rise, between about 1000 and 2500 m; and (d) prevailing deposition on the upper rise proper (below 2500 m), from transport by the SW-trending Western Boundary Undercurrent. Sediments moved by bottom currents have altered the composition and distribution patterns of material transported downslope by offshelf spillover; this mixing of gravity-emplaced and bottom-current-transported sediment obscures depositional boundaries. Moreover, reworking of the seafloor by benthic organisms alters physical properties and changes erodability of surficial sediments by bottom currents. Measurement of current flow above the seafloor and direct observation of the bottom are insufficient to delineate surficial sediment boundaries. Detailed petrologic analyses are needed to recognize the long-term signature of processes and define depositional provinces.     

An approach for the determination of hull-girder loads in a seaway including hydrodynamic impacts

The determination of hull-girder loads in a seaway is of particular importance for the design of marine vehicles. This paper shows how the loads can be determined, considering also the impact loads due to slamming. Results have been presented for a fast patrol boat, although the method can be used for other kinds of surface vessels. The theoretical approach presented in the paper is an extension of the linear strip method used extensively in predicting both ship motions and dynamic loads. The equations have been solved by simulating the ship behaviour in an irregular seaway.     

Seismic evidence for pervasive deformation of oceanic sediments in the Eastern Equatorial Atlantic

Seismic reflection profiles from the equatorial Atlantic off Africa between 12°N and 1°N reveal remarkably widespread deformation of oceanic sediments in an area lacking teleseismic activity. Uplift of abyssal plain sequences has occurred along the eastern extensions of large-offset fracture zones on the Mid-Atlantic Ridge. Between the major transforms pervasive deformation is imaged in the sedimentary column. Diapirism and faulting may have been associated with extensive fluid migration and sediment mobilization. The deformation occurred during the late Cenozoic and was probably related to reactivation of Cretaceous transforms.