δ13C analyses of oceanic particulate organic matter

Seventy-nine δ¹³C analyses of oceanic particulate matter (> 0·μ) from semi-tropical (Gulf of Mexico, Caribbean and Atlantic) and polar (South Indian Ocean) waters showed that the carbon isotope composition of the particulate matter from the cold polar surface waters was lighter ($\text{?24·7}\text{to}\text{?26·0‰}$) than that from the surface in the semi-tropical regions ($\text{?19·8}\text{to}\text{?22·3 ‰}$), reflecting the temperature effect on the photosynthetic fixation of carbon. δ¹³C for deep samples (> 330 m) were generally more negative than the surface samples, except in some well-mixed polar areas.A difference both in organic carbon isotopic composition and percentage organic carbon in the POM and the tops of sediment cores was also apparent; a loss of approximately 95 % of incoming carbon and an increase in ¹³C of several per mille being observed during deposition of particulate matter. This indicates that after settling on the bottom there is extensive diagenesis of the POM by organisms, indicating the non-refractory nature of the organic matter.     

Stoneley waves,Lopez Island noise,and deep sea noise from 1 to 5 Hz

The Lopez Island OBS Intercomparison Experiment provided a data set of sufficient spatial density to allow study of the propagation of shot-generated Stoneley waves as well as ambient background noise. The Stoneley waves were observed propagating at velocities of 20 to 50 m s^-1, Phase velocities were determined by fitting peaks in the frequency wave number spectrum. Group velocities were calculated by narrowly filtering the data and determining the arrival time of the peak in the frequency packet. Particle displacement plots illustrate the surface wave character of these waves. The analysis of the ambient background noise failed to produce a clearly defined dispersion curve yet it did allow bounds to be placed on the phase velocities (20 to 50 m s^-1). The data were modeled using eleven layers overlying a half-space. The results indicated that the top 7 m of the sediment column at Lopez Island is best approximated by two zones. In the upper zone there is a fairly rapid change of shear velocity with depth. This zone overlies a region in which the shear velocity gradient is much lower. Deep ocean background noise recorded by University of Washington ocean bottom seismometers was also examined. Although insufficient data precluded any velocity analysis, definite similarities exist between these data and noise data observed at Lopez Island.Hawaii Institute of Geophysics Contribution No. 1174.     

Sediment blocks on the sea floor in British Columbia fjords

In the deepest parts of Bute and Knight Inlets, British Columbia, unusual blocky mounds of sediment rise abruptly from the otherwise smooth sea floor. The mounds (up to 28 m high, 80 m wide, and 150 m long) display bioturbated surfaces with transverse fractures and elongate depressions. The origin of the mounds and sediment blocks, which contrast with the otherwise flat-lying fjord-bottom strata, remains unknown. Two mechanisms for their formation are considered: (1) subsidence associated with earthquake-induced liquefaction; and (2) uplift driven by the growth of localized gas hydrates in the near-surface sediments.     

INMARSAT — satellite communications

The International Maritime Satellite Organization (INMARSAT) has come into being as a result of conferences by the Inter-governmental Maritime Consultative Organisation (IMCO). Its administration has been set up in London, and the organization has called for tenders for the satellites and ground stations required, and as an interim measure is arranging to use a share of the facilities of existing satellite systems. Its aim is to improve telecommunications facilities for the world's shipping and thus to reduce risks to life and property at sea, increase the efficiency of ship management, and to provide a satellite service, owned by the participating governments, that has been long in demand.     

Coastal Bathymetry from Hyperspectral Remote Sensing Data: Comparisons with High Resolution Multibeam Bathymetry

We present a large-scale quantitative test of a hyperspectral remote-sensing reflectance algorithm. We show that coastal bathymetry can be adequately derived through model inversions using data from the Airborne Visible-Infrared Imaging Spectrometer instrument. Data are analyzed from a shore-perpendicular transect 5 km offshore Sarasota, Florida at water depths ranging from 10 m to 15.5 m. Derived bottom depths are compared to a high-resolution multibeam bathymetry survey. Model-derived depths are biased 4.9% shallower than the mean of the multibeam depths with an RMS error of 7.83%. These results suggest that the model performs well for retrieving bottom depths from hyperspectral data in subtropical coastal areas in water depths ranging from 10 m to 15.5 m.     

Rationalization at sea

UNCLOS is only part of intergovernmental efforts to make sense of the new circumstances offshore. The secretariats of the various UN component organs and agencies have always cooperated on the potential of the marine dimension. Plans and policies are evolving, coastal states are getting encouragement to see the sea as an aspect of foreign policy deserving regional collaboration, and a modest rationalization of global interests is taking shape, albeit slowly.     

Wavimeter

A method of extracting wave parameters from surface displacement measured from a moving platform is presented. The article first presents a method for accurately measuring surface displacement using a single beam altimeter and heave sensor. A least squares approach is presented to estimate wave parameters using vessel velocity and perceived wave frequency that eliminates Doppler due to vessel motion. Two techniques for estimating wave frequency are presented: a block data method using MUSIC and a real-time method using demodulation. Sea trial results demonstrate that this method is as effective as a WaveRider buoy for estimating wave parameters.     

An assessment of the effects of severe weather on the intertidal fauna of the Humber estuary (South Bank), UK—consequences for biological monitoring

A survey of the intertidal fauna of the southern shore of the Humber estuary, UK, was conducted in the week subsequent to a severe storm. Comparison of the results with previous data for the same sites showed no dramatic depletion of the fauna. The observations are discussed with reference to the anticipated effects of physical environmental disturbances. It is concluded that intertidal organisms are adapted to survive the effects of physical disturbance and consequently may offer some benefits in ecological monitoring of pollution.