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Oceanic Outputs

Various workers have estimated the rate of pyrite formation. Berner (1972) summed the sulfur accumulation rates of various sediment types in proportion to their areal coverage and found a flux of about 10% of the river flux. Li (1981) carried out a similar calculation and finds 30% of the river flux, probably indicative of the uncertainty of the approach. Toth and Lerman (1977) established that the decrease of sulfate with depth in sediment pore waters is a function of sedimentation rate. This information was used to estimate the diffusive flux of sulfur into sediments driven by pyrite formation, again a value about 10% of the river flux. Apparently, pyrite [Pg.297]

Evaporite deposition is a much more episodic process and thus difficult to quantify. Because seawater is significantly undersaturated with respect to common evaporitic minerals, like gypsum and halite, evaporites are only formed when restricted circulation develops in an ocean basin in which evaporation exceeds precipitation. A geologically recent example is the Mediterranean Sea of 5-6 Ma ago. At this time, excess evaporation exceeded the supply of ocean water through shallow inlet(s) from the Atlantic Ocean. As salinity increased, first CaS04, then NaCl, precipitated. Over time, salt deposits 2-3 km thick formed. This thickness represents about 40 desiccations of the entire volume of the Mediterranean. How rapidly would the Mediterranean have to evaporate to remove all the sulfate introduced by rivers to the ocean The time-scale T is given by t = y ed where F, is the [Pg.297]

A solution, still controversial, has recently been proposed. This is the loss of sulfate from seawater during hydrothermal circulation through mid-ocean ridges (Edmond et al., 1979). The flow of water through these systems is estimated to be about [Pg.298]


A box model fiar the marine silica cycle is presented in Figure 6.11 with respect to the processes that control DSi and BSi. An oceanic budget is provided in Table 16.3 in which site-specific contributions to oceanic outputs are given. This table illustrates that considerable uncertainty still exists in estimating the burial rate of BSi. Regardless, burial of BSi is responsible for most of the removal of the oceanic inputs of DSi, with the latter being predominantly delivered via river runoff. This demonstrates the importance of the biological silica pump in the crustal-ocean-atmosphere factory. [Pg.418]

Averaging across regions with varying P accumulation rates undoubtedly imparts a relative error of at least 50% to the burial rate value derived here. Also, some restricted environments exhibit quite high but spatially variable P burial rates (e.g., phosphatic continental margin environments, Froelich et al. 1982 hydrothermal iron sediments, Froelich et al. 1977, Wheat et al. 1996). The areal approach is a more direct route to quantifying the burial terms in the P mass balance, and indicates that reactive P burial in continental margin sediments accounts for about 60% of the oceanic output, with deep sea sediments nearly equivalent as a sink. [Pg.396]

Current climate change models have acknowledged weaknesses in their handling of changes in the sun s output, volcanic aerosols, oceanic processes, and land processes that can influence climate change. Some of those uncertainties are large enough, by... [Pg.246]

OTEC power plants can be located either onshore or at sea. The electricity generated can be transmitted to shore by electrical cables, or used on site for the manufacture of electricity-intensive products or fuels (such as hydrogen). For OTEC plants situated on shore to be economical, the floor of the ocean must drop off to great depths very quickly. This is necessary because a large portion of the electricity generated by an OTEC system is used internally to pump the cold water up from the depths of the ocean. The longer the cold water pipe, the more electricity it takes to pump the cold water to the OTEC facility, and the lower the net electrical output of the power plant. [Pg.890]

Winds blowing across the surface of the world s oceans are converted into waves. The total amount of power released by waves breaking along the world s coastlines has been estimated to be 2 to 3 million megawatts, equivalent to the output of about 3,()0(1... [Pg.891]

The failure to identify the necessary authigenic silicate phases in sufficient quantities in marine sediments has led oceanographers to consider different approaches. The current models for seawater composition emphasize the dominant role played by the balance between the various inputs and outputs from the ocean. Mass balance calculations have become more important than solubility relationships in explaining oceanic chemistry. The difference between the equilibrium and mass balance points of view is not just a matter of mathematical and chemical formalism. In the equilibrium case, one would expect a very constant composition of the ocean and its sediments over geological time. In the other case, historical variations in the rates of input and removal should be reflected by changes in ocean composition and may be preserved in the sedimentary record. Models that emphasize the role of kinetic and material balance considerations are called kinetic models of seawater. This reasoning was pulled together by Broecker (1971) in a paper called "A kinetic model for the chemical composition of sea water."... [Pg.268]

A simple model can be used to describe this control of the concentration. In this model the input is from rivers and the output is uptake by reactions in the ocean crust under hydrothermal systems. (An application of this model is given in Section 13.5). Thus... [Pg.270]

The subsequent fate of the assimilated carbon depends on which biomass constituent the atom enters. Leaves, twigs, and the like enter litterfall, and decompose and recycle the carbon to the atmosphere within a few years, whereas carbon in stemwood has a turnover time counted in decades. In a steady-state ecosystem the net primary production is balanced by the total heterotrophic respiration plus other outputs. Non-respiratory outputs to be considered are fires and transport of organic material to the oceans. Fires mobilize about 5 Pg C/yr (Baes et ai, 1976 Crutzen and Andreae, 1990), most of which is converted to CO2. Since bacterial het-erotrophs are unable to oxidize elemental carbon, the production rate of pyroligneous graphite, a product of incomplete combustion (like forest fires), is an interesting quantity to assess. The inability of the biota to degrade elemental carbon puts carbon into a reservoir that is effectively isolated from the atmosphere and oceans. Seiler and Crutzen (1980) estimate the production rate of graphite to be 1 Pg C/yr. [Pg.300]

Table 2. Known inputs and outputs of U to the oceans. Units are 10 g yr or thousand tons per year. References are the most recent primary studies of that flux. Some other fluxes (e.g., groundwater input and input or removal at estuaries) are so poorly known that they cannot be realistically included. Significant uncertainty remains in most of the fluxes listed above so that, within these uncertainties, the U budget can be considered to be in balance. Table 2. Known inputs and outputs of U to the oceans. Units are 10 g yr or thousand tons per year. References are the most recent primary studies of that flux. Some other fluxes (e.g., groundwater input and input or removal at estuaries) are so poorly known that they cannot be realistically included. Significant uncertainty remains in most of the fluxes listed above so that, within these uncertainties, the U budget can be considered to be in balance.
A system, which can be thought of as a lake, an ocean basin, a domain of the mantle or of the crust,. .. has a constant volume V in m3 (Figure 7.1). It receives an input Q of material (water, magma, sediments,. ..) in m3 a 1 and releases an equivalent output. Assuming that the system is well-stirred, C represents volumic concentrations in molm-3 of a conservative chemical species i. By conservative, it is meant (see... [Pg.345]

Additional laser diode technologies recently reported include a continuous-wave rhodamine 700 dye laser with a maximum wavelength output at 758 nm, powered by two laser diodes each operated with two standard AA batteries (RDT E division of the US Naval Command, Control, and Ocean Surveillance Center, San Diego, California), and a tunable laser diode with output laser wavelengths of 650, 780, 850, and 1320 nm (New Focus, Mountain View, California). [Pg.191]

As noted above, it is likely that the calcium input fluxes to the oceans and the outputs fluxes are not always equal. According to Equation (5), this means that the seawater 5 Ca ratio can vary with time. The rapidity with which the seawater 5 Ca can change is dictated by the residence time of calcium in seawater. At present, the residence time is estimated to be about 1 million years (e g., Holland 1978). In the past, the residence time could have been larger or smaller, perhaps by as much as a factor of 5 or even 10, depending on the Ca concentration in seawater (Fig. 12) and the riverine, diagenetic and hydrothermal fluxes of calcium to the oceans. [Pg.279]

Figure 9. A schematic depiction of the apparent Mo isotope budget in the modem oceans, neglecting suboxic sediments. Mean isotopic values for inputs and outputs are indicated, along with the fractional importance of each sediment type for Mo removal. See text for details. Figure 9. A schematic depiction of the apparent Mo isotope budget in the modem oceans, neglecting suboxic sediments. Mean isotopic values for inputs and outputs are indicated, along with the fractional importance of each sediment type for Mo removal. See text for details.
From the perspective of the surface box, the biolimiting elements are supplied via river runoff and from upweUing. The elements are removed via the sinking of biogenic particles and downwelling. Since this model considers only the transport of materials into and out of the ocean and between the two reservoirs, details as to what happens to the elements while they reside in the boxes are not needed other than that they are present in a steady state. In such a case, the input rate of a biolimiting element will equal its output rate. For the surface-water reservoir, the mass balance that describes this steady state is given by... [Pg.229]

Primary outputs are produced essentially by sedimentation and (to a much lower extent) by emissions in the atmosphere. The steady state models proposed for seawater are essentially of two types box models and tube models. In box models, oceans are visualized as neighboring interconnected boxes. Mass transfer between these boxes depends on the mean residence time in each box. The difference between mean residence times in two neighboring boxes determines the rate of flux of matter from one to the other. The box model is particularly efficient when the time of residence is derived through the chronological properties of first-order decay reactions in radiogenic isotopes. For instance, figure 8.39 shows the box model of Broecker et al. (1961), based on The ratio, normal-... [Pg.608]

Determine the pump power, turbine power, net power output, rate of heat added to the heat exchanger by surface ocean warm water, rate of heat removed from the heat exchanger by deep ocean cooling water, cycle efficiency, boiler pressure, condenser pressure, mass flow rate of surface ocean warm water, and mass flow rate of deep ocean cooling water. [Pg.88]


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