Mud and fluid migration in active mud volcanoes in Azerbaijan

Mud volcanic eruptions in Azerbaijan normally last for less than a few hours, and are characterized by vigorous extrusion of mud breccias, hydrocarbon gases, and waters. Recent fieldwork and mapping on four active mud volcanoes show that dormant period activity ranges from quiet to vigorous flow of mud and fluids. Geochemical analyses of expelled waters show a wide range in solute concentrations, suggesting the existence of a complex plumbing system. The mud and fluids have a deep origin, but are sometimes stored in intermediate-depth mud chambers. A mixing model between deep-seated saline waters and shallow meteoric water is proposed.     

Atmospheric forcing of fine-sand transport on a low-energy inner shelf: south-central Louisiana,USA

Hydrodynamic and sediment transport measurements from instrumentation deployed during a 54-day winter period at two sites on the Louisiana inner shelf are presented. Strong extratropical storms, with wind speeds of 7.8 to 15.1 m s^-1, were the dominant forcing mechanism during the study. These typically caused mean oscillatory flows and shear velocities about 33% higher than fair weather (averaging 12.3 and 3.2 cm s^-1 at the landward site, and 11.4 and 2.7 cm s^-1 at the seaward site, respectively). These responses were coupled with mean near-bottom currents more than twice as strong as during fair weather (10.3 and 7.5 cm s^-1 at the landward and seaward sites, respectively). These flowed in approximately the same direction as the veering wind, causing a net offshore transport of fine sand. Weak storms were responsible for little sediment transport whereas during fair weather, onshore sand transport of approximately 25-75% of the storm values appears to have occurred. This contradicts previous predictions of negligible fair-weather sediment movement on this inner shelf.     

Large-scale in situ rotational failure on a low-angle delta slope: The Foreslope Hills,Fraser Delta,British Columbia,Canada

The Foreslope Hills are a series of ridges and troughs covering over 60 km² of the sea floor at the base of the Fraser Delta slope. Internally, the hills consist of blocks of prodelta and delta slope sediment (> 10.6 km³) bounded by offshore dipping faults and shear planes. Stratification within each block generally dips landward, indicating rotational failure. The amount of downslope translation of delta slope sediments was relatively minor. Deformation is restricted to a deep structural trough, suggesting failure resulted from yielding of soft underlying (early Holocene) prodelta sediments in the trough.     

Calibration of visual observations of wave period

Visual observations of wave properties are an important source of statistical information needed for the prediction of design and operational conditions of ocean structures. In particular, mean wave periods are important parameters for predicting the response of ocean structures. The existing calibration studies were based on data sets with a poor correlation between observations and measurements. The data set analysed here show a good correlation indicating the feasibility of collecting further good data sets to provide an adequate calibration to the existing statistical compilations of wave data.     

Theoretical wind wave frequency spectra in deep water——Ⅰ. Form of spectrum

In this part ot the paper theoretical wind-wave spectra nave been derived oy (I) expressing the spectrum in series composed of exponential terms; (2) assuming that the spectrum satisfies a high order linear ordinary differential equation; (3) introducing proper parameters in the spectrum; and (4) making use of some known charateristics of wind-wave spectrum, for instance, the law governing the equilibrium range. The spectrum obtained contains the zero order moment of the spectrum m0, the peak frequency ω0 and the ratio R =ω/ω0 (ω being the mean zero-crossing frequency) as parameters. The shape of the nondimensional spectrum S(ω) = ω0S(ω)/m0(ω=ω/ω0) changes with R and theoretically reduces to a Dirac delta function δ(ω-1) when R = 1. A spectrum of simplified form is given for practical uses, in which R is replaced by a peakness factor P=S(1).     

Effects of pulp bleach plant effluents on hepatic xenobiotic biotransformation enzymes in fish: Laboratory and field studies

The present preliminary report on studies of the influence of pulp bleach plant effluents on hepatic biotransformation enzymes in fish is a part of a major characterisation of biochemical and physiological effects of effluents from pulp industries in Sweden. Our studies on the xenobiotic biotransformation enzymes demonstrate, so far, that the pulp effluents have the potential to strongly induce 7-ethoxyresorufin-O-deethylase activity (EROD) in fish liver and that fish living in the receiving water of an effluent from a pulp bleach plant have induced hepatic EROD activities as well as higher hepatic UDP glucuronyltransferase activities than those living in an unpolluted area. It is thus apparent that measures of induction of biotransformation enzymes in fish liver may be a useful approach in monitoring the presence of potential hazardous compounds released from pulp industries.     

Lower Eocene red-clay sedimentation on the George Bligh/Rockall Channel

Core 7710, recovered on the George Bligh/Rockall Channel, is composed of fine grained ocher-colored sediments rich in ferriferous smectite (montmorillonite, beidellite). These sediments were deposited during early Eocene in a shallow marine environment. Their mineralogic, chemical and isotopic constituents indicate subaerial weathering of lower Eocene intermediate igneous rocks (ferrodiorite, marscoiite) eroded from the still-emergent George Bligh and Rockall Banks. Lack of any post Eocene Sediments may be due to major morphologic and hydrologic changes forming sedimentation gaps.     

Tectonic control over topography and channel sedimentation across the forearc slope of the southern Kurile Trench

A high-resolution seismic survey covering more than 2,000 km² has revealed the processes responsible for the slope morphology and channel sedimentation across the forearc slope-basin of the Kurile Arc–NE Japan Arc collision zone, offshore from Tokachi (Hokkaido, Japan). The dominant slope contours parallel the trench but, in the middle and lower reaches of the southern slope, contours are convex-shaped with an offshore trend. This sector of the slope is traversed diagonally by the Hiroo submarine channel. The offshore-trending convex contours and the channel course have developed through the interplay of tectonic and sedimentary processes, including the development of anticlines, anticline-induced lobe sedimentation and channel avulsion. In its upper reaches, the channel is restricted by a topographic low associated with NNW–SSE-trending anticlines which developed within the upper and middle slope sectors during late Miocene uplift. The uplift timing and trend of these anticlines indicate that they resulted from collision, the channel sedimentology and slope morphology of the middle and lower slopes having been influenced by Pliocene uplift of NE–SW-trending anticlines. The trends of these anticlines parallel those of the Kurile Trench. The Pliocene and early Pleistocene strata of the middle and lower slopes consist of ponded lobe sediments deposited along the palaeo-Hiroo submarine channel on the landward side of the anticlines. As a lobe pile accumulated, the channel thalweg shifted to the north of the stack, allowing the channel to bypass the topographic high formed by the growing stack. Thick levee deposits built up along the channel course during the late Pleistocene and Holocene. These levees, along with the Pliocene and early Pleistocene lobes, are reflected in the present-day sigmoid-shaped, convex offshore-trending contours. Thus, the interplay of subduction- and collision-related anticlines, tectonic-related channel ponding, and avulsion has contributed to the slope morphology of the southern Kurile Trench.     

Vertical migration and mortality of benthos in dredged material: Part III—polychaeta

The survival of benthic invertebrates from dredging and disposal activities is a major environmental concern in such projects. The purpose of the research described in this paper was to determine the ability of benthos (polychaetes, Scoloplos fragilis and Nereis succinea) to migrate vertically in natural and exotic sediments and to determine the survival of benthos when exposed to particular amounts of simulated dredged material.Mortalities generally increased with increased sediment depth, exotic sediment and burial time. Temperature also affected vertical migration and mortalities. These experiments, together with other experiments conducted by us and other workers, indicate that polychaetes in particular, and benthos in general, can survive dredging and disposal projects. Under certain conditions several major taxa (polychaetes, molluscs, crustaceans) can be expected to successfully recolonise disposal sites by vertical migration.     

Digital underwater acoustic voice communications

This paper describes the design of an underwater acoustic diver communication system controlled by a digital signal processor. The speech signal transmission rate is compressed by using linear predictive coding (LPC) and the extracted parameters are transmitted through the water to a synchronized receiver by employing digital pulse position modulation (DPPM). The pulse position in each time frame is estimated by an energy detection and decision algorithm which enables the received LPC parameters to be recovered and used to synthesize the speech signal