The solution speciation and solid-phase suspended particulate fractionation of the trace metals Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb were investigated in the Black Sea, the world's largest anoxic basin. Sequential filtration/ion-exchange and selective leaching techniques were developed for the determination of dissolved and solid-phase trace metal fractionation. Field measurements were compared with the results of a thermodynamic equilibrium model. The transition metals (Mn, Fe, and Co) were controlled by changes in redox state across the oxic/suboxic/anoxic boundary and by metal-sulfide precipitation in the anoxic deep waters. Dissolved transition metal concentrations were low in the surface waters, increased to maxima in the upper anoxic zone, then decreased again into the deep waters. Dissolved Mn and Fe approached saturation with respect to MnS$\sb2$ (haurite) and to FeS (mackinawite) or Fe$\sb3$S$\sb4$ (greigite) in the deep waters. Dissolved Co was best explained in terms of a scavenging/regeneration cycle with Mn-oxyhydroxides across the sulfide interface and coprecipitation of Co with Fe-sulfides in the deep waters. Dissolved Ni was nearly constant with depth. / The Class B metals (Cu, Zn, Cd, and Pb) were high in the surface waters and decreased rapidly across the sulfide interface, consistent with metal-sulfide precipitation below the interface. The dissolved metal fractionation was dominated in the oxic zone by "free" metal species, shifting to dissolved metal-sulfide complexes below the interface. / With the exceptions of Al and Fe, the suspended matter trace metal fractionation was dominated by weak-acid soluble forms. Strong-acid leachable forms, probably metal-sulfide phases, were important in the deep waters for Mn, Fe, and Co. / Source: Dissertation Abstracts International, Volume: 52-02, Section: B, page: 0705. / Major Professor: William M. Landing. / Thesis (Ph.D.)--The Florida State University, 1990.

The distribution patterns of infaunal polychaetes can be influenced by several factors (e.g., predation, competition, and, or disturbance). Adult-larval interactions have been shown to be important in communities where adult densities are high. Manipulative field experiments were used to test the effects of several adult species on the settlement and recruitment of infaunal polychaetes in seagrass beds on Turkey Point Shoal, St. George's Sound in the northern Gulf of Mexico. Interpretation of observed or inferred settlement patterns in field experiments can be difficult and erroneous if little is known of larval settling behavior. I designed experiments to find cues responsible for larval settlement behavior, and to determine if these cues could also alter the spatial pattern at settlement. The deposit feeding adults Aricidea philbinae and Prionospio heterobrachia inhibited the settlement and recruitment of conspecifics both in the field and lab. The tube building adult Americonuphis magna facilitated the settlement and recruitment of A. philbinae, Sphaerosyllis taylori, and Nereis succinea in field experiments. Only Prionospio larvae seem to seek out sediments with a past history of Americonuphis magna in laboratory settling experiments. Polychaete tubes had little or no effect on polychaete settlement. Both inhibition and facilitation seem to govern recruitment sequences in these low adult density assemblages. The active larval settlement behaviors I found reveal that some mechanisms of the adult-larval interactions observed are attributable to larval behavior (both avoidance and attractance). It is evident that larval behavior and adult-larval interactions are important in structuring the small-scale patchiness in the seagrass bed community. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0623. / Major Professor: Robert J. Livingston. / Thesis (Ph.D.)--The Florida State University, 1987.

The concept of the submarine equilibrium profile has long been established. / This dissertation first proposes a conceptual model based on the well established concept. Then it proposes an analytical model with a differential equation which is based on the Airy wave theory and the wave-induced asymmetrical onshore/offshore sediment particle movement proposed by Cornaglia. / A "SIMPLEX" non-linear regression algorithm was used to write a computer program "SIMPYA" in GWBASIC. The computer program approaches two unknown parameters in the equation using sample profile data plotted on some coasts around continental U.S., namely, the southeastern U.S. Atlantic coast, the Gulf of Mexico coast and the Pacific coast. The sample profiles were selected according to criteria derived from the conceptual model. The result of regression analysis was very encouraging. This model permitted a more perceptive geological interpretation of various profile morphology features. / A wave tank, a wave generator and an adjustable platform were designed and constructed by the author, and were used in an effort to verify the analytical model. The unique platform provides independently adjustable settings of slope and depth of the platform, on which the sand behavior under the wave can be observed. This design eliminates the need of a very long flume (up to several thousand foot long) and bulky handling of sand, which are conventional in marine profile experimental research. However, scale problems were too great to be overcome completely. / The Application of the model may include assessment of profile stability, profile evolutionary trends, development of transitional models and coastal engineering calculations. / Source: Dissertation Abstracts International, Volume: 52-04, Section: B, page: 1917. / Major Professor: William F. Tanner. / Thesis (Ph.D.)--The Florida State University, 1991.

For the first time an ocean model is used to assimilate oceanic tomography data in an upper ocean model of the northeast Pacific with the goal of estimating the time independent density field, and thus the slow manifold circulation structure. / The assimilation procedure works by minimizing the cost function, which generalizes the misfit between the observations and their model counterparts, in a least-squares sense, plus a penalty term. This minimization is done consistently with the constraint that the model dynamics must be exactly satisfied. The model consists of integrating the model equations forward in time over the period which data are going to be assimilated. Data misfits between the model and the observation are then calculated and the adjoint equations of the model are integrated backward using the data misfits as forcing. It is necessary to determine the gradient of the cost function with respect to the control variables (the density field). The gradient is found using the model and adjoint variables and it is used in a minimization algorithm to determine a new density field. The minimization procedure utilizes a limited memory quasi-Newton method. / The results indicate that the assimilation procedure works very well. For the twin experiments, the final estimated density recovers the Levitus density field as expected and as fast as in 10 iterations. For the experiments with the Navy layered ocean circulation model (NRLM) output, the density can be estimated through the assimilation procedures. The estimated density field improves the the Levitus climatological density data which are biased and makes the subtropical gyre stronger in the northeast Pacific region. / The proof of the identity between the discretization of the continuous adjoint equations and the adjoint equations which are from discretized model equations with the Arakawa C has been carried out. / Source: Dissertation Abstracts International, Volume: 56-07, Section: B, page: 3667. / Major Professor: James J O'Brien. / Thesis (Ph.D.)--The Florida State University, 1995.

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The response of coastal systems to global change is currently not well understood. To understand current patterns and predict future trends, we establish a geologic record of coastal change along the Gulf of Mexico coast. A study examining the natural versus anthropogenic mechanisms of erosion reveals several sand sources and sinks along the upper Texas coast. It appears that hurricane washover and offshore sand deposits are minimal sand sinks, while flood-tidal deltas are areas of significant sand sequestration. Additionally, it appears that damming of rivers has had only a minimal effect on sedimentation along the upper Texas coast. However, hard engineering structures placed on the beach have exacerbated erosion due to trapping sand of that would otherwise be in the longshore transport system. Coastal sand budgets are derived to put geologic events (such as hurricanes and erosion) into context. Sand budgets often use engineering assumptions to establish sand transport within a coastal system. However, a disconnect typically exists between engineering principles and geologic concepts when quantifying these budgets. Geologic principles are relied upon to calculate a sand budget and evaluate published sediment budgets. This reveals that assuming too shallow a depth of closure can result in ~17% error in the total calculated sediment flux and an error of ~40% of the total longshore transport flux for the upper Texas coast. This suggests that revised approaches are necessary to accurately represent sand transport within the coastal zone. The long-term probability of hurricane impacts in the western Gulf of Mexico is constructed. For south Texas, an intense hurricane landfall probability of ~.46% is established for the past ~5,000 years. Based on published studies, this is similar to the intense hurricane impact probability of ~.39% for the eastern Gulf of Mexico. Studying the evolution of San Luis Pass provides a unique opportunity to study the response of accelerated sea-level rise and hurricane impacts on the evolution of a natural tidal delta system and adjacent Galveston Island. This study reveals an increased sand flux into San Luis pass tidal delta, and suggests that the erosion along Galveston Island has more than doubled over historic time relative to geologic time.

A multi-scale asymptotic theory is derived for the evolution and interaction of currents and surface gravity waves in water of finite depth, under conditions typical of coastal shelf waters outside the surf zone. The theory provides a practical and useful model with which wave-current coupling may be explored without the necessity of resolving features of the flow on space and time scales of the primary gravity-wave oscillations. The essential nature of the dynamical interaction is currents modulating the slowly evolving phase of the wave field and waves providing both phase-averaged forcing of long, infra-gravity waves and wave-averaged vortex forces for the low-frequency current and sea-level evolution equations. Analogous relations are derived for material tracers and density stratification that include phase-averaged, Stokes-drift advection, including by a vertical Stokes pseudo-velocity that is the incompressible companion to the horizontal Stokes velocity. This theory is used to study the effect of waves on the evolution of large-scale erodible beds. In particular, the formation of certain up-current rotated, shore-connected bars is investigated. It is hypothesized that these bars form due to an instability of the bottom topography in the presence of a storm driven flow. This hypothesis is reviewed in the light of the presence of both waves and currents. It is shown that waves can significantly affect the instability. The effects of different wave parameters are investigated. Steady flow and boundary condition assumptions are also examined.

In 1974, newly available satellite observations unveiled the presence of a giant ice-free area within the Antarctic ice pack, which persisted throughout the winter, and formed again in the next two winters. Subsequent research showed that deep convective overturning kept the waters ice-free, through the massive release of heat rising from the deep sea. While the polynya has aroused continued interest among climate scientists, it has not reappeared since 1976. Here we use model experiments to show that deep convection in the Southern Ocean, common in current generation climate models, is highly sensitive to anthropogenic forcing, and ceases in many models when forced by a high emissions climate change scenario. The slowdown in deep ventilation follows from the gradual freshening of polar surface waters, a trend which is borne out by observations over recent decades. Our results suggest that deep convection in the Southern Ocean will be less common in future, and may have already been significantly reduced compared to the pre-industrial period, with important consequences for ocean circulation and climate. / En 1974, des observations satellite nouvellement disponibles révélèrent la présence d'une géante surface d'eau libre au sein de la glace de mer entourant l'Antarctique, qui persista tout au long de l'hiver et réapparut les deux hivers suivants. Les recherches qui suivirent montrèrent que les eaux étaient maintenues libres de glace par la convection profonde, permettant à une grande quantité de chaleur de remonter des profondeurs pour être ensuite libérée dans l'atmosphère. Si la polynya continue de susciter l'intérêt des climatologues, elle n'est cependant pas réapparue depuis 1976. Nous utilisons ici des expériences de modélisation pour montrer que la convection profonde dans l'Océan Austral, commune dans les modèles de climat actuels, est fortement sensible au forçage anthropique, et cesse dans beaucoup de modèles quand ceux-ci sont forcés par un scénario de fortes émissions. Le ralentissement de la ventilation profonde résulte de la baisse progressive de la salinité des eaux de surface, une tendance corroborée par les observations des dernières décennies. Nos résultats suggèrent que la convection profonde dans l'Océan Austral sera moins fréquente dans le futur, et a peut-être déjà été significativement affaiblie relativement à la période préindustrielle, avec d'importantes conséquences pour la circulation océanique et le climat.

Current sea-ice models evolve towards higher spatial resolutions and levels of convergence of their numerical solution, which refines their simulated ice deformation fields, while still employing the values of the dynamic parameters used in earlier models. In this work, we investigate the effect of spatial resolution and convergence on the choice of optimal model parameters by comparing drag coefficients and ice compressive and shear strength sensitivity studies conducted with a viscous-plastic sea-ice model of the Arctic. We observe that convergence impacts the optimal parameters greatly and that a low converged solution induces ice drift biases that cannot be rectified by changing the parameter values. The performed experiments do not allow drawing conclusions on the effect of spatial resolution but indicate that varying the resolution of the model wind forcing alters the optimal parameters if this forcing is derived using a non-linear spatial interpolation scheme. / Les modèles de glace de mer évoluent aujourd'hui vers une résolution spatiale et un niveau de convergence numérique accrus, ce qui rafine les champs de déformation simulés, mais emploient toujours d'anciennes valeurs de paramètres dynamiques. Dans cette étude, nous examinons l'effet de la résolution et de la convergence sur les paramètres dynamiques optimaux en étudiant la sensibilité d'un modèle visco-plastique de glace de mer à la valeur des coefficients de friction et de résistance en compression et tension de la glace. Nous observons que le niveau de convergence affecte largement les paramètres optimaux et qu'une convergence insuffisante induit des biais sur la dérive des glaces qui ne peuvent être rectifiés en changeant leur valeur. Les expériences effectuées ne permettent pas de tirer de conclusions quant à l'effet de la résolution du modèle mais indiquent que la résolution des vents de forçage affecte les paramètres optimaux s'ils sont dérivés d'une méthode d'interpolation spatiale non-linéaire.

Simulation of stratigraphy coupled with sequence stratigraphic and backstripping analysis quantitatively defines the timing and magnitude of geologic events, including the history of sediment supply, tectonism and eustasy. This provides a quantitative basis for interpreting the mechanisms causing these variations. This computer simulation comprises algorithms that model subsidence and uplifts, eustasy, flexural response of sediment and water loads, compaction, traction- and suspension-load deposition, gravity-flow sedimentation, carbonate production and redistribution, and erosion. Backstripping analysis can provide a geohistory, burial history, sediment accumulation history, porosity history, and a first approximation of the tectonic subsidence or uplift history. A backstripping analysis of a stratigraphic section produced by the two-dimensional simulator demonstrates the error due to overcompensating for the flexural response to sediment loading with a calculation that assumes local isostasy. These errors reinforce the necessity to use a two- or three-dimensional simulation or backstripping technique to accurately define the eustatic and tectonic history of a region. Simulation results of the Last Chance Canyon study show that documented stratal patterns are a product of the interaction of a dynamic depositional system, with constant parameters, fed by alternating siliciclastic sand and carbonate production, a constant subsidence rate of 0.4 cm/ky, and a eustatic sea-level history that contains "third-order" and higher periodicity cycles. A hierarchy of stratigraphic packaging is presented that include continental encroachment megasequences, transgressive-regressive facies-supersequences, complete and incomplete sequences, component groups and components. Sediment supply, tectonism, and eustatic fluctuations produce these packages by changing the accommodation space with characteristic rates and patterns. The geometry of the substrate and bathymetric changes strongly influence the geometry of stratal surfaces and distribution of lithofacies. The response of these variables is simulated independently to identify their unique stratal signatures. Examples from different settings (passive margin, mixed carbonate-siliciclastic sediment supplies, carbonate ramp, and steep carbonate platform margin, and others) demonstrate how siliciclastic and carbonate depositional systems interact with the bathymetric conditions produced by these variables. Simulation results show that the relative change of sea level is the sum of total subsidence (tectonic subsidence, flexure loading and compaction) and eustasy.