Concentration in oceans

The concept of average residence time, or turnover time, provides a simple macroscopic approach for relating the concentrations in ocean reservoirs and the fluxes between them. For the single box ocean in Fig. 10-17 the rate of change of the concentration of component n can be expressed as... 

When cyanoacetylene (5), which is produced when an electric discharge is passed through a mixture of methane and nitrogen, is dissolved in a phosphate buffer a stable enol-phosphate (6) is formed. Pyrophosphate is produced when neutral aqueous solutions of (6) and orthophosphate are heated, and the phosphorylation of UMP has been achieved. However, from a study of the rate of phosphorylation and a consideration of environmental factors, especially the likely phosphate concentration in oceans, it is suggested that (6) is not an important intermediate in prebiotic phosphorylation. The conversion of the 3 -phosphate of 0 2 -cyclocytidine (7) into 2, 3 -cyclic CMP under mild conditions in aqueous solution has... 

Although the free amino acids are present only at very low concentrations in oceanic waters, their importance in most biological systems has led to an inordinate amount of effort toward their determination in seawater. A sensitive, simple, and easily automated method of analysis, the colorimetric nin-hydrin reaction, has been known in biochemical research for many years. In order for the method to be useful in seawater, the amino acids had to be concentrated. This concentration was usually achieved by some form of ion exchange [251]. An automated method not using a concentration step was developed by Coughenower and Curl [252]. While the method was used successfully in Lake Washington, its limit of detection (0.5 imol/l) is just too great for most oceanic samples. 

Rainbow, P.S. 1989. Copper, cadmium and zinc concentrations in oceanic amphipod and euphausiid crustaceans, as a source of heavy metals to pelagic seabirds. Mar. Biol. 103 513-518. 

Kinetic effects or the activity of organisms may result in a deviation from the thermodynamically expected situation. In the euphotic zone the formation of As(III) is related to primary production, may be as a result of detoxifying processes (Andreae, 1979). The oxidation of Mn(II) appears to be kinetically hindered while Se(IV) and Se(VI) are, as only element, present in similar concentrations in oceanic waters (Bruland, 1983). 

The alternative hypothesis suggests a direct route, where long-range oceanic transport can account for the presence of PFCAs in the Arctic Ocean and thus in Arctic biota [14,163, 164]. As will be discussed later in more detail, PFOS, PFOA, PFNA and PFHxS have been reported in open ocean waters of the Pacific and Atlantic and in coastal waters of Japan, Korea and China [95,112,165]. Modelling studies indicate that the observed PFOA concentrations in oceans can be accounted for by historical and projected PFOA emissions [14, 163, 164]. 

Although it is generally believed that the world ocean is the ultimate sink of these chemicals there are only a few reliable reports on the concentration of PCBs in ocean water. This is largely due to the fact that reliable sampling has proven to be difficult as their concentrations in ocean water are extremely low [121]. 

Urea ((NH2)2CO) is excreted by larger organisms, can be a product of bacterial organic matter decomposition, and is a highly labile form of N for plankton nutrition (Bronk, 2002). Reports of concentrations in oceanic waters are relatively scarce, but are quite low (<0.5 pM Antia et al, 1991). There are currently two methods commonly used to measure urea concentrations—the urease method (McCarthy, 1970) and the monoxime method (Mulvenna and Savidge, 1992 Price and Harrison, 1987). 

The ratio of the boron isotopes and °B is known to depend on ambient pH in the boron incorporated in the carbonate shells of marine foraminifera (Sanyal et ai, 1996 Sanyal et al., 2001). The use of boron isotopes as an indicator for seawater paleo-pH has been extended to the calculation of past CO2 concentrations in ocean surface waters and in the atmosphere (Spivack, 1993 Sanyal et al., 1997 Pearson and Palmer, 1999, 2000 Sanyal and Bijma, 1999 Palmer and Pearson, 2003). Sources of uncertainty in these estimates include the fractionation of boron isotopes during incorporation in carbonate shells, effects of diagenesis, the assumptions needed to calculate CO2 concentrations from pH, and the influence of changing boron isotope ratios in ambient seawater (Lemarchand et al., 2000 Lemarchand et al., 2002). The latter problem is especially serious for estimates based on samples older than the 15 Myr residence time of boron in the oceans. 

The concentration of Ni in the lithosphere is 55p.gg (Li, 2000) and the concentration of dissolved Ni in stream water is 2p,gL (Turekian, 1971). More recent data on the concentration of dissolved Ni in average world river water indicates the value to be 0.8 xgL (Gaillardet et al., 2003) and the Ni concentration in ocean water to be 0.47 xgL (Chester, 2000). Natural emissions of Ni to the atmosphere are dominated by windblown dusts while anthropogenic sources that represent 65% of all emission sources are dominated by fossil-fuel... 

Measured oxygen concentrations in ocean surface waters as a function of temperature from the WOCE data base. The line marks the saturation value with atmospheric oxygen at a salinity of 35. 

Lead inputs to oceanic systems have been measured8. Using isotope correlation, they identified the prime aerosol source as leaded gasoline. Profiles of lead concentrations in ocean water cluster between 0.02 pg/1 and 0.04 pg/1 for water below 500 m shallow water coastal concentrations may range from 0.07 to 0.35 pg Pb/19. While values as high as 10 jug Pb/1 have been reported, it is possible that some of these higher values reflect shipboard contamination9. ... 

Li (1981) has proposed that the distribution coefficients reflect adsorption-desorption reactions at the surface of mineral grains. To emphasize this point, Li plotted a slightly different distribution coefficient (log Cop/Q , where Qp and Cs are the concentrations in oceanic pelagic clay sediments and seawater respectively vs the first hydrolysis constants of the metals or the dissociation constant of the oxyanion acids. The argument is that those elements that hydrolyze the strongest will adsorb the... 

There are indications that release of Ra-226 by decomposing organic matter is a mechanism of some significance in maintaining the Ra-226 concentrations in ocean water (42, 43). If this additional supply of Ra-226 is expressed as a constant production rate Q (grams liter 1 yr 1), then a steady-state concentration-depth profile may be obtained from the differential equation... 

Grill, E.V. (1982) Kinetic and thermodynamic factors controlling manganese concentrations in oceanic waters. Geochimica et Cosmochimica Acta, 46, 2435-2446. 

Schulte, S., Benthien, A., Andersen, N., Muller, P.J., Ruhlemann, C., Schneider, R.R., 2003. Stable carbon isotopic composition of the C37 2 alkenone A proxy for concentration in oceanic surface... 

Here, (A) is the concentration of a substance measured in moles/1 and is the activity coefficient calculated as a function of the overall ionic strength in the solution. For infinitesimal diluted solutions, the activity coefficients assume the value of 1 hence, activity equals concentration. In ocean water, the various monovalent ions, or ion pairs, display activity coefficients somewhere around 0.75 whereas the various divalent ions, or ion pairs, display values around 0.2 (cf. Table 15.2, last column). 

Natural tritium concentrations in ocean surface waters and in young groundwater are of the order of 1 tritium atom per 10 hydrogen atoms. This is the reason that tritium concentrations are reported as TU (Tritium Units). One TU stands for a tritium to hydrogen ratio [ H]/[H] of 10. The activity of a water sample with a tritium concentration of 1 TU is equivalent to 3.2 pCi or 0.12 Bq per liter of H2O. The production rate of natural tritium is about 0.5 0.3 atoms cm s (Craig and Lai 1961) leading to natural tritium values in ocean surface waters of about 0.2 TU (Dreisigacker and Roether 1978). 

Assuming a steady-state system in the continental run-off and the deposition of minerals in the ocean, the residence time of the elements in sea water can be estimated from the yearly rate of transport in the rivers and their average concentration in ocean water. For elements such as Zn, Cu, Ni, and Ti, the mean residence time in sea water before incorporation in solid phases is of the order of 10 years. 

The zinc content of soil limonite was found to be always greater than that of the soil matrix in Tennessee subsurface soil samples (251), Burns and Fuerstenau (40) determined the occluded heavy metal concentrations in oceanic manganese nodules via an electron probe. They found that nickel and copper occurred in the high manganese bands while cobalt occurred predominantly in the iron rich areas. 

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