Ocean, lead

Radium, like most other group II metals, is soluble in seawater. Formation of Ra and Ra by decay of Th in marine sediments leads to release of these nuclides from the sediment into the deep ocean. Lead, in contrast, is insoluble. It is found as a carbonate or dichloride species in seawater (Byrne 1981) and adheres to settling particles to be removed to the seafloor. 

The disposal of highly concentrated effluents (after seawater desalination) back into the ocean leads to increased pollution. This will result in the destruction of local and marine flora and fauna, and can be expected to introduce other ecological hazards. Because of this, it probably will be worthwhile to install a mineral recovery unit at the desalination plants, despite the extra cost, just to reduce the possibility of serious ecological problems. 

On the other hand, a nutrient-type trace metal like Zn attains a concentration of dissolved Zn that is approximately five times greater in the old, nutrient-rich deep waters of the North Pacific than they are in the young, nutrient-poor North Atlantic deep waters. Its distribution in both ocean basins is similar to that of silicic acid. The efficiency with which Zn is recycled in the ocean leads to its relatively long oceanic residence time. 

Another requirement for long-term simulations arises from the restricted water exchange of the B altic Sea with the open ocean leading to long residence times in the order of 30 years (e.g.. Dobs et al., 2004). This implies that long-term simulations, which should describe the response of the whole Baltic Sea to changes in the external forcing, have to cover at least 30 years to include the time span of the residence time. 

However, Genda and Abe (2005) and Kramers (2003) have shown that the Earth was likely to have had a very early liquid water ocean. Consequently, atmospheric loss probably took place in the presence of a liquid water ocean, leading to enhanced volatile loss. 

As we saw in Special Topic 10.1, a large amount of carbon dioxide from the atmosphere eventually enters the ocean. The first step in this process can be understood in terms of the model used in this chapter to describe how gas dissolves in a liquid. The colhsions between the CO2 gas particles and the surface of the ocean lead to the movement of about 9.2 x IOI3 kg of CO2 into the oceans per year. There is a competing rate... 

Finally, what of anaemia This, too, is a symptom of scurvy, but is not a physiological failure in the sense of those discussed above. In this case, vitamin C acts on the inorganic iron in food in the stomach and intestines, converting it from the insoluble form usually found in food (Fe3+) to the soluble form (Fe2+) that we can absorb in our intestines. (This is the reverse of the reaction that took place on a huge scale in the Pre-cambrian oceans, leading to the precipitation of insoluble iron into banded iron formations, discussed in Chapter 3). Without adequate supplies of vitamin C, we cannot absorb enough iron to stock red blood cells with haemoglobin (which contains iron), and so we develop anaemia. 

They suggested that most of the carbonate dissolution in the deep ocean (Fig. 9.5) occurs within the sediments (85 %). The extension of their results from Pacific and Indian Ocean to the Atlantic Ocean leading to 120 10 molyr of global dissolved carbon fluxes from sediments may, however, be critical because of the completely different deep-water conditions in the Indo-Pacific and the Atlantic. Deep ocean waters in the Indian and Pacific Oceans are known to be much older and depleted in CO implying that a much higher proportion of calcite dissolution contributes to the total alkalinity input there. However, despite this problem of different bottom-... 

Figure 2 Changes in concentration of atmospheric lead at Bermuda and dissolved surface oceanic lead near Bermuda from the mid-1970s to the mid-1990s. (Data reproduced with permission from Wu J and Boyle EA (1997) Lead in the western North Atlantic Ocean Completed response to leaded gasoline phaseout. Geochimica et Cosmochimica Acta 61 3279-3283 and from Huang S, Arimoto R and Rahn KA (1996) Changes in atmospheric lead and other pollution elements at Bermuda. Journal of Geophysical Research 101 21 033-21 040.)...

Patterson, C. C. The isotopic composition of meteoric, basaltic and oceanic leads, and the age of the earth [summary]. Conf. on Nuclear Processes in Geologic Settings, Proc. 36—40 (1953). 

Looking back at the earth from space was Alan Thorndike with an eye toward a minimal description of ice and climate. By area, floating sea ice represents the most dramatic seasonal variation in global ice cover. A minimal description of the balance of energy at the surface of the ocean leads one to the conclusion that the presence of ice is required. For some it is sufficient to know that we observe ice in the polar seas, but to others addressing the question of whether an ice-free polar ocean can exist re-... 

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

More CO2 can actually be absorbed chemically into the ocean than the above reaction sequence suggests. Terrestrial weathering of rocks containing carbonate, such as limestone, and subsequent aerial or riverine transport, means that the ocean is enriched in carbonate. Keeping and Kj constant implies, through eqns. (3) and (4), that enhancing the oceanic [COj ] leads to a greater level of... 

Changes in surface temperature elsewhere in the globe are likely to have a lesser impact on carbon or DMS production. For example, the warming that a doubling of atmospheric COj could produce in the Southern Ocean has been modelled to lead to decreased carbon uptake, but enhanced biological productivity, due to the temperature effect on phytoplankton growth." This would lead to an approximately 5% increase in DMS production and a lesser increase in CCN. There is thus a negative feedback here, but only of minor impact. 

Loss of radon in the ocean occurs typically through radioactive decay (producing four short-lived daughters before decaying to °Pb) or loss to the atmosphere at the air-sea interface. Loss of radon owing to turbulence or diffusion at the air-sea interface leads to a depletion of radon with respect to "Ra, allowing for studies on gas exchange at this interface. ... 

The majority of published °Pb reports address the utility of °Pb as a geochronological tool rather than as an element that is involved in complex biogeochemical cycles. Nonetheless, some of these studies do provide insight into the geochemical behavior of °Pb and °Po. Nearly all of the lead in the world s surface oceans is believed to be of anthropogenic origin—derived from combustion... 

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