Knowledge of physical properties of near-surface sediments is an important requirement for many studies of the seafloor. Dynamic or Free Fall Penetrometers (FFP), instrumented with accelerometers, are widely used to assess the mechanical properties of the sediment by deriving penetration resistance from the deceleration response of the probe as it impacts and embeds the seabed. Other field investigations, a priori knowledge or a very basic description of the type of sediment (such as a description of the sediment as soft, medium or hard) derived from studying the deceleration response (accelerometer-time histories) are used for sediment identification prior to the application of an appropriate strength determination model. In many cases this information is site-specific and in others the penetration resistance is overestimated due to the dilatory effects observed in sediment with an undetected grain fraction. In this study variables affecting a dynamic penetrometer-sediment interaction system are identified. Using data from field investigations and literature we found a relationship among five variables: peak acceleration, embedment depth, total embedment time, velocity of impact and grain size. This is used to formulate a sediment identification model. The model accounts for variables that may vary widely within one deployment and it can be applied to other FFPs with different physical characteristics (such as a different mass or size). This may lead to the increased use of FFP as a deployment tool for rapid in situ characterization of the seafloor.

Abstract. Experiments and analysis have shown that the ductile compressive yield stress (at -10øC at 4 x 10 -5 s -1) of S2 saline ice, an orthotropic material whose crystallographic c axes are randomly oriented in the plane perpendicular to the long axis of the columnar grains [Michel, 1978], loaded triaxially both across and along the columnar-shaped grains obeys Hill's [1950] criterion under low to intermediate levels of confinement. Correspondingly, the ratio of inelastic strains can be described by the attendant associated flow rule. IntroductionSeveral factors affect the failure of a sheet of first-year sea ice. These include wind and ocean currents and hence the strain rate of the ice, the temperature profile through the sheet, the microstructure (as well as macrostructure) of the material, the spatial variation in thickness, plus stress concentrators such as refrozen leads and other flaws. Experimental ProcedureThe saline ice that was used in the investigation was prepared in the manner described by Schulson and Nickolayev [1995]. In short, salt water of salinity 23%0 was unidirectionally solidified in the laboratory, leading to the growth of sheets of S2 columnar ice of around 300 mm thickness. Cubes were cut from the sheets, with care being taken to remove the upper granular and the lower skeletal layers before sampling. The growth direction was parallel to one set of edges of the specimens. Figure 1 shows the ice and defines the coordinate system to which reference is made; X1 and X2 are perpendicular to the columns (i.e., define the horizontal plane within a natural sheet), and X 3 is parallel to the long axis of the columns. . The material appears to be a good facsimile of the first-year sea ice described by Weeks and Ackley [1982].The triaxial compression experiments were carried out at -10øC _+ 0.2øC using the same apparatus as in the previous studies, namely, a true triaxial, servohydraulic loading system. The loads were applied proportionally through brass brushtype platens [Gies, 1988] Results General ObservationsUnder all conditions the ice exhibited macroscopically ductile behavior. Faulting was not observed, and the ice continued to support load up to the point that the load was removed.Three kinds of response (o-• versus •) were observed. Under low confinement, strain hardening was followed by strain softening once the stress reached a maximum at a small strain (• • 0.005), as commonly observed under uniaxial compression (Figure 3a). Under intermediate confinement the flow stress generally did not reach a maximum, but it did reach a more or less steady state value at around • = 0.01 ( Figures 3b, 3c, 3e, and 3g). Under high confinement, only strain hardening was seen (Figures 3f and 3h).

Seventy-three men and 72 women made lexical decisions to target words that followed sentences constructed so that the last word was a sexual double-entendre. Prime target relatedness, erotic versus nonerotic target, stimulus onset asynchrony, and participant's gender were varied in a between-subjects design. A second analysis that substituted sentence context for prime target relationship also was conducted. Data were collected on the emotionality and social acceptability of priming sentences and target words. Results revealed that, as with previous research on neutral words, prime target relatedness facilitated lexical decisions. Additionally, there was evidence of slowing in making lexical decisions when erotic material was presented or was part of a contextual bias. This delay was accentuated in women. A model that proposes that sexual words evoke a more complex processing sequence is presented. The model suggests that appraisal and checking or editing mechanisms, which are accentuated in women, help explain the phenomenon.

This study investigated the interferences caused by high humic acid concentrations on the adsorption of coplanar and noncoplanar polychlorinated biphenyls (PCBs) on coconut shell activated carbon. In particular, the research focuses on the application of activated carbon as a reactive cap for contaminated sediment sites, a possible intervention to reduce contaminant flux through pore water, and to organisms in aquatic environments. Kinetic and equilibrium studies were conducted using activated carbon as a sorbent for individual PCB congeners including BZ 1, 52, 77, 153, and 169, respectively, in the presence and absence of humic acid. Results showed that preloading of activated carbon with humic acid significantly reduced the adsorption affinity for all selected PCB congeners. Experiments conducted without preloading of activated carbon demonstrated that desorption upon subsequent spiking with humic acid (simulating long-term exposure to pore water that contains high humic acid concentrations) was not found to be statistically significant, and varied with coplanarity of PCBs. Results provide important information for the design of reactive caps in sediments where high concentrations of dissolved organic carbon are found, and highlight the importance of considering site conditions when designing effective reactive caps.

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