Government response to marine pollution from ships

The Marine Pollution Control Unit (MPCU) is the competent national authority for discharging the Secretary of State for Transport responsibility for pollution from ships under the Prevention of Oil Pollution Act 1971 and subsequent legislation covering other hazardous substances. It is an integral part of The Coastguard Agency, an executive agency of The Department of Transport. MPCU is responsible for maintaining the National Contingency Plan, for monitoring and assessing all pollution incidents within UK waters including dealing with pollution from ships and for advising on/co-ordinating shoreline counter pollution operations, and for fostering and maintaining international relationships for mutual support.     

Tracking the last sea-level cycle: seafloor morphology and shallow stratigraphy of the latest Quaternary New Jersey middle continental shelf

Seafloor geomorphology and surficial stratigraphy of the New Jersey middle continental shelf provide a detailed record of sea-level change during the last advance and retreat of the Laurentide ice sheet (120 kyr B.P. to Present). A NW–SE-oriented corridor on the middle shelf between water depths of 40 m (the mid-shelf “paleo-shore”) and 100 m (the Franklin “paleo-shore”) encompasses 500 line-km of 2D Huntec boomer profiles (500–3500 Hz), an embedded 4.6 km² 3D volume, and a 490 km² swath bathymetry map. We use these data to develop a relative stratigraphy. Core samples from published studies also provide some chronological and sedimentological constraints on the upper <5 m of the stratigraphic succession.The following stratigraphic units and surfaces occur (from bottom to top): (1) “R”, a high-amplitude reflection that separates sediment >46.5 kyr old (by AMS ¹⁴C dating) from overlying sediment wedges; (2) the outer shelf wedge, a marine unit up to 50 m thick that onlaps “R”; (3) “Channels”, a reflection sub-parallel to the seafloor that incises “R”, and appears as a dendritic system of channels in map view; (4) “Channels” fill, the upper portion of which is sampled and known to represent deepening-upward marine sediments 12.3 kyr in age; (5) the “T” horizon, a seismically discontinuous surface that caps “Channels” fill; (6) oblique ridge deposits, coarse-grained shelly units comprised of km-scale, shallow shelf bedforms; and (7) ribbon-floored swales, bathymetric depressions parallel to modern shelf currents that truncate the oblique ridges and cut into surficial deposits.We interpret this succession of features in light of a global eustatic sea-level curve and the consequent migration of the coastline across the middle shelf during the last 120 kyr. The morphology of the New Jersey middle shelf shows a discrete sequence of stratigraphic elements, and reflects the pulsed episodicity of the last sea-level cycle. “R” is a complicated marine/non-marine erosional surface formed during the last regression, while the outer shelf wedge represents a shelf wedge emplaced during a minor glacial retreat before maximum Wisconsin lowstand (i.e., marine oxygen isotope stage 3.1). “Channels” is a widespread fluvial subarial erosion surface formed at the late Wisconsin glacial maximum 22 kyr B.P. The shoreline migrated back across the mid-shelf corridor non-uniformly during the period represented by “Channels” fill. Oblique ridges are relict features on the New Jersey middle shelf, while the ribbon-floored swales represent modern shelf erosion. There is no systematic relationship between modern seafloor morphology and the very shallowly buried stratigraphic succession.     

Generation of geostrophic vortices caused by displacements of a part of the bottom of a basin

Within the framework of the general linear statement of the problem, we determine the conditions of generation of a geostrophic current in a layer of uniform rotating fluid for small displacements of the bottom of a basin. We deduce an equation relating the equilibrium shape of the surface of the fluid with residual deformations of the bottom and find its general solution. It is shown that the geostrophic current is generated only in the presence of residual deformations. We present numerical estimates of the intensity of the generated geostrophic formation for a model of motion of the bottom. The investigated mechanism of generation of geostrophic vortex fields is especially efficient in the shelf zone of the ocean. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Effects of PCBs sorbed to algal paste and sediments on the stress protein response (HSP70 family) in the eastern oyster, Crassostrea virginica.

This study examined the stress protein response (HSP70 family) of reproductively inactive oysters fed 0.7 g algal paste containing 0, 0.35 and 3.5 micrograms polychlorinated biphenyls (PCBs) daily. A second set of treatment groups investigated the combined effect of PCBs and sediments (0.3 g sediments daily per oyster) on HSP70 response. After 8 weeks of PCB exposure, oyster tissues (mantle and gill) were sampled and analyzed for HSP70. Preliminary results did not show a significant effect in HSP70 response in oysters fed PCB sorbed to algal paste, albeit PCBs accumulated up to 1342 ng/g dry weight in the mantle, and up to 180 ng/g dry weight in gill tissues. However, the addition of sediments caused a significant increase in HSP70 levels of gills and mantle, although the mantle was less sensitive to the sediments.     

Immune response of greenback flounder Rhombosolea tapirina after exposure to contaminated marine sediment and diet.

Non-specific immune response of greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments was examined. Reference sediments from Port Sorell and contaminated sediments from Deceitful Cove, Tasmania, Australia were investigated. Hatchery-reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. Phagocytic capacity and lysozyme response in flounder were examined on cessation of exposure trial. Significant differences were found in phagocytic capacity and lysozyme response between treatments. Exposure to contaminated sediment, irrespective of diet or benthic disturbance elicited inhibition of phagocytic efficiency in flounder. Disturbance of contaminated sediment stimulated lysozyme activity. The immune response in flounder indicates potential immunotoxicity of sediment from Deceitful Cove.     

Increased potential for NAD(P)H-dependent reactive oxygen species production of hepatic subcellular fractions of fish species with in vivo exposure to contaminants.

The present study investigated the proposed involvement of contaminant-stimulated reactive oxygen species (ROS) production in disease processes in fish. NAD(P)H-dependent ROS production of subcellular fractions was determined by the iron/EDTA-mediated oxidation of 2-keto-4-methiolbutyric acid. Hepatic cytosolic NADPH-dependent and microsomal NAD(P)H-dependent ROS production were increased 51-160% (P < 0.05) in rainbow trout (Oncorhynchus mykiss) 15 weeks after a single i.p. injection of polychlorobiphenyl (PCB) (100 mg Clophen A50 kg-1 wet wt.). Hepatic microsomal NADH-dependent ROS production was 114% higher in perch (Perca fluviatilis) from PCB-contaminated Lake J?rnsj?n compared to clean Lake V?nern, Sweden. Hepatic mitochondrial NADH-dependent, cytosolic NADH-dependent and microsomal NADPH-dependent ROS production were variously elevated up to 160% in flounder (Platichthys flesus) at various sites along two pollution transects near to the ports of Rotterdam and Amsterdam, Netherlands. Overall the data indicate increased potential for ROS production in liver of fish exposed to field pollution, and support the hypothesis of oxidative stress as a mechanism of contaminant-mediated disease in fish.     

A wavelet for predicting the time-domain response of vertically tethered systems

The response wavelets for tether tension and the displacement of a package on the end of a tether are derived from a linear, frequency-domain model of vertically tethered systems using inverse fourier transform techniques. These wavelets are convolved with a record of ship displacement to predict the instantaneous tension and displacement to an accuracy of better than 20% for a typical system. Although snap loads are non-linear and the response cannot be calculated while the tether is slack, the onset of zero tension — a precursor to snap loads — is predicted by the wavelet. Thus, extreme and potentially hazardous conditions are foreseeable with the wavelet and this information can be used in real-time to guide operations at sea.     

Video cathodoluminescence microscopy of diagenetic cements and its applications

Diagenetic studies of sedimentary rocks using cold cathodoluminescence (CL) microscopy have been severely limited because of the very low intensity of visible luminescent emissions, which required long photographic exposure times, and because of the difficulty in obtaining quantitative data from CL observations. The solution to this problem is to fit the microscope with a high-sensitivity digital colour video camera linked to a computer with image enhancement and image analysis software. The new technique described in this paper:

• produces digital CL images of consistent high quality, both quickly and cheaply;

• controls the capture and editing of CL images, to reveal detailed textural information even from minerals exhibiting low level luminescence such as quartz;

• acquires quantitative information on pore systems and the abundance of cement zones from CL images.

Examples are presented to demonstrate the high quality of images produced in this way and the range of uses to which the new technique can be applied. The ability to image exactly the same field of view in both plane polarised light and CL is a particular advantage. Image analysis techniques have been developed to give a statistical characterisation of both pore systems and cement phases that infill them. The abundance of contrasting cement zones seen in CL can be measured and the abundance of cement phases can be mapped across a reservoir. The history of porosity occlusion can be reconstructed quantitatively and integrated with burial history and hydrocarbon migration. Porosity can be measured accurately and, since the technique obtains data on pore geometry as well as abundance, the pore system can be characterised by pore size distributions and pseudo-capillary pressure curves. This also opens the possibility of estimating permeability from thin sections.