Marine mean residence time

Schell, W. R., Concentrations, Physical-Chemical states and mean residence times of 210Pb and 210Po in marine and estuarine waters, Geochem. Cosmochim. Acta, 41, 1019-1031 (1977). 

It is believed that CH3I is produced by marine algae and released from seawater, and that this constitutes the main source of stable iodine in the atmosphere (Lovelock et al., 1973). Elemental iodine may be liberated from the sea surface by ultraviolet light (Miyake Tsunogai, 1963), or by the action of ozone (Garland Curtis, 1981), but I2 is dissociated very rapidly by photochemical action, and its mean residence time in daylight air is less than a minute. 

Problems are, therefore, particularly liable to occur where effluents are not rapidly dispersed in the open sea, such as shallow coastal waters, firths, estuaries, fyords with narrow outlets and inland seas. Marine pollution in such areas has been intensively studied in recent years and effects on life in the shallow waters of the North Sea, of the discharge of sewage and industrial effluents from the huge population of Northern Europe have been discussed by Cole [389]. The situation is also serious in the Baltic, Mediterranean and Black Sea, which are enclosed areas of water with narrow entrances, where the volume of water is small in relation to the possible burden of pollution. The mean residence time for water in the Baltic has been stated to be 21 years [148] and in such an isolated body of water there is a likelihood of progressive build-up of metal concentrations. 

Whitfield, M. (1979), The Mean Oceanic Residence Time (Mort) Concept. - A Rationalization", Marine Chemistry 8, 101-123. 

Seawater-crustal partition coefficient (KV(sw)) versus mean oceanic residence time (ty). Note that this is a log-log plot. Source-. From Turner, D. R., et al. (1980). Marine Chemistry 9, 211-218. 

Shown in Table 8.9 are chemical analyses of mean river water and seawater, along with residence times of the species and a comparison of relative concentrations in mean river water and the ocean. As in the discussion of the hydrologic cycle, the residence time of species in seawater, t, equals the amount of that species in the reservoir (the ocean), divided by its rate of input or output (which must be equal at steady state). The input is in streams and groundwaters discharging into the ocean. The output is through adsorption and/or precipitation in and on solids that end up in marine sediments. 

Neutral hydroxide Si(OH)4 is predominant in the natural water, the content of anion Si(0H)30 is in a lesser degree. The continental river water discharge is responsible for 0.2 x 10 tons of soluble silicon species. The mass of Si compounds in the ocean is 4, 110 x 1tons, and the residence time of Si in the marine waters is 20,550 years. The transport of silicon from terrestrial to oceanic ecosystems is not counterbalanced by the reverse transport. In addition to the soluble species, the content of silicon in river particulate matter is about 120 /rg/L. This gives the elemental transport of 4.8 x 10 tons/yr. The total estimate of river water fluxes from the global land area to the ocean is 5.0 x 10 tons/yr. Aeolian migration of silicon is responsible for 0.47 X 10 tons per year. It means the annual global land losses (river and wind fluxes) are 5.47 x 10 tons (Dobrovolsky, 1994). 

So, annual accumulation of nitrogen in the Yellow Sea was 1,229 kt/yr. (+47% from input) and the residence time of nitrogen was 1.5 year. This means that the N content in marine water was doubling every 3 years during 1994-1997. It leads to excessive eutrophication and pollution of the Yellow Sea. 

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