Concentrations of unsubstituted polynuclear aromatic hydrocarbons in bay mussels (Mytilus edulis) from Oregon, USA

Concentrations of fifteen unsubstituted polynuclear aromatic hydrocarbons (PNAH) were measured in Mytilus edulis from two sites in Yaquina Bay, Oregon, USA, during 1979–1980. There were significant differences in PNAH levels between the two populations. The average total concentration in mussels inhabiting the more industrialized bayfront was 986·2 μg/kg compared with 273·9 μg/kg in mussels from a more remote site across the bay. Substantial differences were found in the concentrations of different PNAH in M. edulis examined during this study. The smaller more water soluble, compounds were concentrated to one or two orders of magnitude above the larger, less soluble PNAH.     

A Pull-Up Shallow Water Seismometer

An inexpensive Pull-Up Shallow Water Seismometer (PUSS) has been designed and built to conduct long range seismic refraction experiments in the North Sea and the continental shelf around Britain, with the particular goal of studying the crustal and lithospheric structure under the epeirogenic basin of the North Sea. Signals from a gimbal-mounted 3-component geophone and a hydrophone are frequency modulated and mixed with clock and flutter correction signals before being recorded on a standard speed cassette tape recorder, with one hour of recording time. A 100 hour programmable timer allows the interval between the time of reset of the clock and each shot window of optional 5 or 10 min duration, to be preselected. The PUSS is launched and recovered using a pull-up technique originally developed for current meters. The replay system is also described.In May 1976 sea trials of 5 PUSSes were conducted along a 200 km refraction line in the North Sea. The encouraging performance of the equipment resulted in the decision to build a further 10 units and to proceed with a 400 km refraction line planned for the summer of 1977.     

An experimental facility for testing loaded structures in a high hydrostatic pressure environment and an application to axially loaded columns

An experimental facility is described for the testing of structures under a combined axial load and hydrostatic pressure load. This facility was used to determine the effects of hydrostatic pressure (up to 6000 psi) on the load-carrying capacity of slender metal columns. There appeared to be no significant effect in this case.     

A seismic refraction study of cretaceous oceanic lithosphere in the Northwest Pacific Basin

A seismic refraction study on old (110 Myr) lithosphere in the northwest Pacific Basin has placed constraints on crustal and uppermantle seismic structure of old oceanic lithosphere, and lithospheric aging processes. No significant lateral variation in structure other than azimuthally anisotropic mantle velocities was found, allowing the application of powerful amplitude modeling techniques. The anisotropy observed is in an opposite sense to that expected, suggesting the tectonic setting of the area may be more complex than originally thought. Upper crustal velocities are generally larger than for younger crust, supporting current theories of decreased porosity with crustal aging. However, there is no evidence for significant thickening of the oceanic crust with age, nor is there any evidence of a lower crustal layer of high or low velocity relative to the velocity of the rest of Layer 3. The compressional and shear wave velocities rule out a large component of serpentinization of mantle materials. The only evidence for a basal crustal layer of olivine gabbro cumulates is a 1.5 km thick Moho transition zone. In the slow direction of anisotropy, upper mantle velocities increase from 8.0 km s^-1 to 8.35 km s^-1 in the upper 15 km below the Moho. This increase is inconsistent with an homogeneous upper mantle and suggests that compositinal or phase changes occur near the Moho.     

Maternal transfer of bioactive polychlorinated aromatic hydrocarbons in spawning chinook salmon (Oncorhynchus tschawytscha)

The biological potency (relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin. TCDD) of planar polychlorinated aromatic hydrocarbons (PCHs) in extracts of eggs and flesh from spawning female chinook salmon (Oncorhynchus tschawytscha) from Lake Michigan was determined by measuring the induction of 7-ethoxyresorufin O-deethylase activity in H-4-II-E rat hepatoma cells. TCDD-equivalents in flesh and egg samples ranged from 0 to 115·8 pg/g, and were approximately 5-fold greater in eggs than in flesh. These results suggest that the maternal transfer of PCHs may play a role in determining the reproductive success of Lake Michigan chinook salmon.     

Thickening of the oceanic layer in the Pacific Ocean

A statistical analysis of published seismic refraction results in the Pacific Ocean confirms the existence of a progressive thickening of the oceanic layer with age, following an inverse exponential law. There is no strong indication in the Pacific data of an increase in the thickness of layer 2 with decreasing spreading rate.Contribution No. 93 of the Département Scientifique of the Centre Océanologique de Bretagne, B.P. 337, 29200, Brest, France.     

The method of calculating the current velocity's verticla component in problems of fluid dynamics in reservoirs

A new algorithm for calculating the vertical velocity is suggested. Horizontal current velocity components are expressed through level inclination and wind/temperature forcing. The acquired relations are given in the difference form, with the accuracy being sufficiently high. The algorithm is tested using cases where a numerical solution is matched up with an exact one. The derived data are subsequently analysed. Translated by Vladimir A. Puchkin.     

Geoacoustic and physical properties of carbonate sediments of the Lower Florida Keys

 Near-surface sediment geoacoustic and physical properties were measured from a variety of unconsolidated carbonate sediments in the Lower Florida Keys. Surficial values of compressional and shear speed correlate with sediment physical properties and near-surface acoustic reflectivity. Highest speeds (shear 125–150 m s^-1; compressional 1670–1725 m s^-1) are from sandy sediments near Rebecca Shoal and lowest speeds (shear 40–65 m s^-1; compressional 1520–1570 m s^-1) are found in soft, silty sediments which collect in sediment ponds in the Southeast Channel of the Dry Tortugas. High compressional wave attenuation is attributed to scattering of acoustic waves from heterogeneity caused by accumulation of abundant shell material and other impedance discontinuities rather than high intrinsic attenuation. Compared to siliciclastic sediments, carbonate sediment shear wave speed is high for comparable values of sediment physical properties. Sediment fabric, rather than changes due to the effects of biogeochemical processes, is responsible for these differences.     

Interference fringes on GLORIA side-scan sonar images from the Bering Sea and their implications

GLORIA side-scan sonographs from the Bering Sea Basin show a complex pattern of interference fringes sub-parallel to the ship's track. Surveys along the same trackline made in 1986 and 1987 show nearly identical patterns. It is concluded from this that the interference patterns are caused by features in the shallow subsurface rather than in the water column. The fringes are interpreted as a thin-layer interference effect that occurs when some of the sound reaching the seafloor passes through it and is reflected off a subsurface layer. The backscattered sound interferes (constructively or desctructively) with the reflected sound. Constructive/destructive interference occurs when the difference in the length of the two soundpaths is a whole/half multiple of GLORIA's 25 cm wavelength. Thus as range from the ship increases, sound moves in and out of phase causing bands of greater and lesser intensity on the GLORIA sonograph. Fluctuations (or wiggles) of the fringes on the GLORIA sonographs relate to changes in layer thickness. In principle, a simple three dimensional image of the subsurface layer may be obtained using GLORIA and bathymetric data from adjacent (parallel) ship's tracks. These patterns have also been identified in images from two other systems; SeaMARC II (12 kHz) long-range sonar, and TOBI (30 kHz) deep-towed sonar. In these, and other cases world-wide, the fringes do not appear with the same persistence as those seen in the Bering Sea.     

Effects of organic pollutants on methanogenesis,sulfate reduction and carbon dioxide evolution in salt marsh sediments

Anaerobic salt marsh sediments were amended with a variety of organic pollutants and the effects on methanogenesis, sulfate reduction and carbon dioxide evolution were examined. Addition of 1000 μg g^?1 (dry weight sediment) Arochlor 1221, lindane, endrin, benzene and phenanthrene resulted in no significant effects on the activities studied. Methanogenesis was inhibited by 1000 μg g^?1toxaphene, PCP, chlordane, naphthalene, DDT, Kepone and heptachlor and by 100 μg g^?1 PCP and toxaphene. At 1000 μg g^?1 naphthalene and toxaphene and 100 μg g^?1 PCP, a period of initial inhibition of methanogenesis was followed by stimulation relative to controls. Arochlor 1254 (1000 μg g^?1) and Temik (500 and 10 μg g^?1) stimulated methanogenesis from the outset. Temik at 500 μg g^?1 gave the greatest stimulation of methanogenesis (900% of controls) of any of the compounds studied. Sulfate reduction was inhibited by 1000 μg g^?1 PCP, toxaphene, naphthalene and chlordane and by 500 μg g^?1 atrazine and 100 μg g^?1 heptachlor. Sustained inhibition of sulfate reduction by naphthalene, toxaphene and PCP may have contributed to the stimulation of methanogenesis. Carbon dioxide evolution was not significantly affected by most of the compounds studied except for 100 μg g^?1 PCP and 1000 μg g^?1 aphthalene, each of which gave significant inhibition in only one of three experiments.Concentrations of individual organic pollutants required to cause observable effects were high. It is concluded that, except for highly polluted sediments, methanogenesis, sulfate reduction and CO₂ evolution would not be affected by the compounds studied here at concentrations typically found in the environment.