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101.
Understanding of the role of oceanic input in nutrient loadings is important for understanding nutrient and phytoplankton
dynamics in estuaries adjacent to coastal upwelling regions as well as determining the natural background conditions. We examined
the nitrogen sources to Yaquina Estuary (Oregon, USA) as well as the relationships between physical forcing and gross oceanic
input of nutrients and phytoplankton. The ocean is the dominant source of dissolved inorganic nitrogen (DIN) and phosphate
to the lower portion of Yaquina Bay during the dry season (May through October). During this time interval, high levels of
dissolved inorganic nitrogen (primarily in the form of nitrate) and phosphate entering the estuary lag upwelling favorable
winds by 2 days. The nitrate and phosphate levels entering the bay associated with coastal upwelling are correlated with the
wind stress integrated over times scales of 4–6 days. In addition, there is a significant import of chlorophyll a to the bay from the coastal ocean region, particularly during July and August. Variations in flood-tide chlorophyll a lag upwelling favorable winds by 6 days, suggesting that it takes this amount of time for phytoplankton to utilize the recently
upwelled nitrogen and be transported across the shelf into the estuary. Variations in water properties determined by ocean
conditions propagate approximately 11–13 km into the estuary. Comparison of nitrogen sources to Yaquina Bay shows that the
ocean is the dominant source during the dry season (May to October) and the river is the dominant source during the wet season
with watershed nitrogen inputs primarily associated with nitrogen fixation on forest lands. 相似文献
102.
The effect of ionic strength (I), pCO2, and temperature on the dissolution rate of calcite was investigated in magnesium-free, phosphate-free, low calcium (mCa2+ ≈ 0.01 m) simple KCl and NaCl solutions over the undersaturation range of 0.4 ≤ Ωcalcite ≤ 0.8. First-order kinetics were found sufficient to describe the rate data where the rate constant (k) is dependent on the solution composition. Rates decreased with increasing I and were faster in KCl than NaCl solutions at the same I indicating that Na+ interacts more strongly with the calcite surface than K+ or that water is less available in NaCl solutions. Rates increased with increasing pCO2 and temperature, and their influences diminished at high I. Arrhenius plots yielded a relatively high activation energy (Ea ≈ 20 ± 2 kJ mol− 1) which indicated that dissolution was dominated by surface-controlled processes. The multiple regression model (MR) of Gledhill and Morse (2006a) was found to adequately describe the results at high I in NaCl solutions, but caution must be used when extrapolating to low I or pCO2 values. These results are consistent with the hypothesis that the mole fraction of “free” solvent (X“free”H2O) plays a significant role in the dissolution kinetics of calcite with a minimum value of 45–55% required for dissolution to proceed in undersaturated solutions at 25–55 °C and pCO2 = 0.1–1 atm. This hypothesis has been incorporated into a modified version of the MR model of Gledhill and Morse (2006a) where X“free”H2O has replaced I and the Ca2+ and Mg2+ terms have been dropped: 相似文献
103.
104.
In this paper, we derive three conservation laws and three invariants of motion for the generalized Gardner equation. These
conserved quantities for internal waves are the momentum, energy, and Hamiltonian. The approach used for the derivation of
these conservation laws and their associated invariants of motion is direct and does not involve the use of variational principles.
It can be easily applied for finding similar invariants of motion for other general types of KdV, Gardner, and Boussinesq
equations. The stability and conservation properties of discrete schemes for the simulations of internal waves propagation
can be assessed and monitored using the analytical expressions of the constants of motion that are derived in this work. 相似文献
105.
Crustal architecture in formerly contiguous basement terranes in SE Australia, Tasmania and northern Victoria Land is a legacy of late Neoproterozoic–Cambrian subduction-related processes, culminating in formation of the Delamerian–Ross orogen. Structures of Delamerian–Ross age were subsequently reactivated during late Mesozoic–Cenozoic Gondwana breakup, strongly influencing the geometry of continental rifting and providing clues about the origins and configuration of the pre-existing basement structures. An ocean–continent transform boundary developed off western Tasmania follows the trace of an older Paleozoic strike-slip structure (Avoca–Sorell fault system) optimally oriented for reactivation during the final separation of Australia from Antarctica. This boundary cuts across rocks preserving an earlier record of arc–continent collision during the course of which continental crust was subducted to mantle depths and Cambrian mafic–ultramafic island arc rocks were thrust westwards over late Neoproterozoic–Cambrian passive margin sequences. Collision was accompanied by development of a foreland basin into which 520–600 Ma arc-derived detrital zircons were shed. Following a reversal in subduction polarity, and change to transcurrent motion along the Gondwana margin, Tasmania migrated northward along the proto-Avoca fault system before entering a subduction zone located along the Heathcote–Governor fault system, precipitating a second collision, south-vergent thrusting, and tectonic reworking of the already accreted Cambrian arc–forearc assemblages and underlying passive margin sequences. 相似文献
106.
Brandi Kiel Reese David W. Finneran Heath J. Mills Mao-Xu Zhu John W. Morse 《Aquatic Geochemistry》2011,17(4-5):567-582
The accurate and precise measurement of total sulfide has been of major interest for well over a century. The most commonly used method involves the formation of a methylene blue?Csulfide complex and spectrophotometric measurement of its concentration. The study presented herein compares the two most commonly used methods as outlined in Standard Methods for the Examination of Water and Wastewater (in APHA, Standard methods for the examination of water and wastewater, Washington, 1960) and by Cline (Limnol Oceanogr 14:454?C458, 1969). In addition, this study clarifies the existing confusion of Cline??s reagent preparation procedure, as it is apparent that various interpretations exist among research groups regarding reagent preparation. After evaluating both methods with respect to precision and accuracy, detection limit, sample storage time, and ease of use, the method outlined in Cline was determined to be superior. Furthermore, we suggest that the reagent concentration has to be optimized depending on the range of sulfide concentrations to increase the accuracy and precision of the method. 相似文献
107.
Patrick L. Barnard Maarten van Ormondt Li H. Erikson Jodi Eshleman Cheryl Hapke Peter Ruggiero Peter N. Adams Amy C. Foxgrover 《Natural Hazards》2014,74(2):1095-1125
The Coastal Storm Modeling System (CoSMoS) applies a predominantly deterministic framework to make detailed predictions (meter scale) of storm-induced coastal flooding, erosion, and cliff failures over large geographic scales (100s of kilometers). CoSMoS was developed for hindcast studies, operational applications (i.e., nowcasts and multiday forecasts), and future climate scenarios (i.e., sea-level rise + storms) to provide emergency responders and coastal planners with critical storm hazards information that may be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources within complex coastal settings. The prototype system, developed for the California coast, uses the global WAVEWATCH III wave model, the TOPEX/Poseidon satellite altimetry-based global tide model, and atmospheric-forcing data from either the US National Weather Service (operational mode) or Global Climate Models (future climate mode), to determine regional wave and water-level boundary conditions. These physical processes are dynamically downscaled using a series of nested Delft3D-WAVE (SWAN) and Delft3D-FLOW (FLOW) models and linked at the coast to tightly spaced XBeach (eXtreme Beach) cross-shore profile models and a Bayesian probabilistic cliff failure model. Hindcast testing demonstrates that, despite uncertainties in preexisting beach morphology over the ~500 km alongshore extent of the pilot study area, CoSMoS effectively identifies discrete sections of the coast (100s of meters) that are vulnerable to coastal hazards under a range of current and future oceanographic forcing conditions, and is therefore an effective tool for operational and future climate scenario planning. 相似文献
108.
S. P. Regan T. C. Sangster D. D. Meyerhofer K. Anderson R. Betti T. R. Boehly T. J. B. Collins R. S. Craxton J. A. Delettrez R. Epstein O. V. Gotchev V. Yu. Glebov V. N. Goncharov D. R. Harding P. A. Jaanimagi J. P. Knauer S. J. Loucks L. D. Lund J. A. Marozas F. J. Marshall R. L. Mccrory P. W. Mckenty S. F. B. Morse P. B. Radha W. Seka S. Skupsky H. Sawada V. A. Smalyuk J. M. Soures C. Stoeckl B. Yaakobi J. A. Frenje C. K. Li R. D. Petrasso F. H. SÉguin 《Astrophysics and Space Science》2005,298(1-2):227-233
109.
110.
We report on numerical experiments to test the sensitivity of Lagrangian coherent structures (LCSs), found by identifying ridges of the finite-time Lyapunov exponent (FTLE), to errors in two systems representing the California Current System (CCS). First, we consider a synthetic mesoscale eddy field generated from Fourier filtering satellite altimetry observations of the CCS. Second, we consider the full observational satellite altimetry field in the same region. LCS are found to be relatively insensitive to both sparse spatial and temporal resolution and to the velocity field interpolation method. Strongly attracting and repelling LCS are robust to perturbations of the velocity field of over 20% of the maximum regional velocity. Contours of the Okubo–Weiss (OW) parameter are found to be consistent with LCS in large mature eddies in the unperturbed systems. The OW parameter is unable to identify eddies at the uncertainty level expected for altimetry observations of the CCS. At this expected error level, the FTLE method is reliable for locating boundaries of large eddies and strong jets. Small LCS features such as lobes are not well resolved even at low error levels, suggesting that reliable determination of lobe dynamics from altimetry will be problematic. 相似文献