Heat flow and mass wasting in the Wilmington Canyon Region: U.S. Continental Margin

The average corrected heat flow in the Wilmington Canyon region, an area of inferred slope instability, is 35 ± 10 mW/m². This average heat flow is marginally consistent with the 46 ± 9 mW/m² measured at other North Atlantic sites over 160 m.y. old. High topographic relief causes most of the variability in surface heat flow and may lower the mean surface heat flow. There is no significant difference between the average corrected heat flow of 35 ± 10 mW/m² in sediment slide areas and the average corrected heat flow of 34 ± 10 mW/m² in undisturbed sediments.     

Behavioural Effects of Chemically Dispersed Oil and Subsequent Recovery in Diploria strigosa (Dana)

Abstract. Survival and behaviour of the hermatypic coral Diploria strigosa was studied during 6–24 h doses with water-accomodated fractions of chemically dispersed crude oil, and for a subsequent recovery period of 1 month. Experiments utilized a flow-through laboratory dosing procedure and incorporated petroleum hydrocarbon measurements in order to simulate a major but short-term oil spill in shallow subtidal benthic reef environments. Chemically dispersed oil treatments consisted of Arabian Light Crude oil with Corexit 9527 or BP1100WD at 1–20 ppm concentrations of oil.
In general, effects observed were sub-lethal, temporary, and associated with the highest concentrations tested. Responses to the presence of dispersed oil at 20ppm for 24 h included mesenterial filament extrusion, extreme tissue contraction, tentacle retraction and localized tissue rupture. The nature and severity of reactions during the dosing phase varied between colonies and treatments, but colonies typically resumed normal behaviour within 2 h to 4 d of the recovery period. It therefore seems unlikely that observed biological effects would impair long-term viability.     

Annual Anthropogenic Carbon Transport into the North Pacific Intermediate Water through the Kuroshio/Oyashio Interfrontal Zone: An Estimation from CFCs Distribution

Vertical distribution of anthropogenic carbon content of the water (exDIC) in the Oyashio area just outside of the Kuroshio/Oyashio Interfrontal Zone (K/O Zone) was estimated by the simple 1-D advection-diffusion model calibrated by the distribution of chlorofluorocarbons (CFCs). The average concentration of exDIC for = 26.60–27.00 is multiplied by the volume transport of Oyashio water into the North Pacific Intermediate Water (NPIW) to estimate the annual transport of exDIC into NPIW through K/O Zone. The estimated transport of exDIC was 0.018–0.020 GtC/y, which corresponds to 15% of the whole total exDIC accumulation in the temperate North Pacific. A simple assessment using the NPIW 1-box model indicates that the current study explains at least 70% of the total annual transport of exDIC into NPIW, and that small exDIC sources for NPIW still exists in addition to K/O Zone.     

Optimisation of a catalytic procedure for the determination of total iodine in seawater

A precise method for the determination of total iodine in seawater, which uses a Technicon Auto-Analyser II system and is based on Truesdale and Spencer's (1974) and Truesdale and Smith's (1975) earlier works with a catalytic procedure, is described. The procedure operates over a range of 30–80 μg1^?1 of iodine. As requested by Mark (1973), the way in which the procedure can be varied to suit other applications, and therefore ranges, is explained in detail. The standard deviation at the 50 μg1^?1 level was found to be 0.12 μ1^?1 showing that the method's precision exceeds most, if not all, previously published procedures for this variable. This high degree of resolution makes the procedure suitable for oceanic investigations. The effects of varying the reaction time, the temperature at which the reaction proceeds and the salinity of samples and standards are described. The advantages of using a Technicon Auto-Analyser II system rather than an Auto-Analyser I system are discussed. With slight modification the procedure can also be used in the measurement of river flow where sodium iodide is used as tracer in the dilution method.     

An ocean bottom,microprocessor based seismometer

We describe the design and construction of an ocean bottom seismometer configured as a computer, based on an Intersil IM6100 microprocessor plus appropriate peripheral devices. The sensors consist of triaxial 1 Hz seismometers and a hydrophone, each sensor channel being filtered prior to digitizing so that typical noise spectra are whitened. Digital data are recorded serially on magnetic tape. The instrument is placed on the ocean bottom by allowing it to fall freely from just below the surface. An acoustic system allows precise determination of instrument position, acoustic recall, and transmission of operational information to the surface. Release from an expendable anchor is accomplished by redundant pyrotechnic bolts which can be fired by acoustic command or by precision timers.The operational flexibility provided by the micro-computer, which executes the DEC PDP8/E instruction set, enables optimum use of the 6-hr recording capacity (at 128 samples/second/channel) in the context of the particular experiment being performed.

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Long-term recovery of a Louisiana brackish marsh plant community from oil-spill impact: vegetation response and mitigating effects of marsh surface elevation

Oil spills can have significant, short-term, negative impacts on coastal marshes, but the long-term effects and eventual recovery are not well documented, particularly in brackish marshes. The goals of this investigation were to: (1) document the long-term recovery of a Louisiana brackish marsh plant community impacted by a 1985 oil spill; (2) separate the effect of the oil spill on marsh deterioration from ambient rates of marsh deterioration; and (3) assess the relative importance of residual oil in the sediment and decreased marsh surface elevation in the failure of certain areas to recover. A total of 68 permanent plots previously established in 1985 were re-surveyed for plant and soil recovery in the fall of 1989. Although substantial (and near total) vegetative recovery was evident by significant increases in live and total vegetative cover, many of the plots that were initially heavily impacted by oil still displayed elevated levels of total saturated hydrocarbons in the soil. August 1990 measurements of plant photosynthetic response and edaphic variables revealed no significant differences between control plots and plots heavily impacted by oil that displayed vegetative regrowth. Rates of wetland land loss in the oiled marsh during an 8-year period that bracketed the time of the spill were within the historical range measured for this site and similar to the land loss rates of adjacent reference marshes. Results from a manipulative field transplant experiment indicated that the long-term failure of certain small areas to revegetate was primarily due to a decrease of marsh surface elevation (increased flooding stress), not a residual oil effect.