Concentration oceanic surface waters

The oceanic distribution of cobalt is similar to that of manganese, although cobalt concentrations are 10-100 times smaller maximum concentrations are 100-300 pM in surface waters, decreasing to 10 pM at depths below 1000 m. As concentrations of cobalt in seawater are so low, it may become biolimiting in open ocean surface waters. 

Tsunogai and Nozaki [6] analysed Pacific Oceans surface water by consecutive coprecipitations of polonium with calcium carbonate and bismuth oxychloride after addition of lead and bismuth carriers to acidified seawater samples. After concentration, polonium was spontaneously deposited onto silver planchets. Quantitative recoveries of polonium were assumed at the extraction steps and plating step. Shannon et al. [7], who analysed surface water from the Atlantic Ocean near the tip of South Africa, extracted polonium from acidified samples as the ammonium pyrrolidine dithiocarbamate complex into methyl isobutyl ketone. They also autoplated polonium onto silver counting disks. An average efficiency of 92% was assigned to their procedure after calibration with 210Po-210Pb tracer experiments. 

In general, silver concentrations in surface waters of the United States decreased between 1970-74 and 1975-79, although concentrations increased in the north Atlantic, Southeast, and lower Mississippi basins (USPHS 1990). About 30 to 70% of the silver in surface waters may be ascribed to suspended particles (Smith and Carson 1977), depending on water hardness or salinity. For example, sediments added to solutions containing 2 pg Ag/L had 74.9 mg Ag/kg DW sediment after 24 h in freshwater, 14.2 mg/kg DW at 1.5% salinity and 6.9 mg/kg DW at 2.3% salinity (Sanders and Abbe 1987). Riverine transport of silver to the ocean is considerable suspended materials in the Susquehanna River, Pennsylvania — that contained as much as 25 mg silver/kg — resulted in an estimated transport of 4.5 metric tons of silver to the ocean each year (USEPA 1980). The most recent measurements of silver in rivers, lakes, and estuaries using clean techniques show levels of about 0.01 pg/L for pristine, nonpolluted areas and 0.01 to 0.1 pg/L in urban and industrialized areas (Ratte 1999). 

One with concentrations of metals corresponding to open-ocean surface water with an information value for total iron concentration. 

The relationship between the rate constant for ligand-metal binding kf) and the concentration of free metal ion [M"+] in oceanic surface waters for the biologically essential trace metals. Data plotted from Table 1 in Hudson, J. M and F. M. M. Morel (1993). Deep Sea Research, 40, 129-150. 

In contrast to the atmosphere, where much can be learned from a relatively small number of 14C sampling locations, the sea presents a formidable sampling problem. The sea does not achieve the nice vertical and zonal uniformity characteristic of the troposphere. The well-mixed surface layer of the sea, generally 50-100 meters deep but occasionally deeper, appears to achieve a uniform concentration but only vertically the levels of excess 14C in the mixed layer varies considerably from place to place. This arises partly from the upwelling of subsurface water of lower 14C content which perturbs the concentration of surface water in many areas of the ocean, adding to the difficulty of interpreting sea water 14C measurements. 

Figure 7. nC concentrations in C02 extracted from Pacific and Indian Ocean surface waters (7,16,44, 56)... 

No simple correlation between chlorophyll a and DMS concentration exists in oceanic surface waters. However, average surface water DMS concentrations show relatively small variations over large extents of the oceans. The variations that are observed may be attributted to factors such as phytoplankton variability, seasonal changes in water masses, differences in vertical mixing in the water column, and ventilation of DMS to the atmosphere. 

Average DMS concentrations in surface waters and in the atmosphere over the Southern Ocean were similar to values reported for other world ocean areas. 

Our experimental results must be considered in the context of seasonal changes in mean irradiance and dissolved iron concentrations for ocean surface waters in our study region. Smith and van Hilst (2003) estimate mean mixed-layer irradiances of 96 58 fiE m 2 s 1 and 180 + 110 fiE m 2 s 1 in the southern Ross Sea for the periods November... 

PFSAs and PFCAs were first observed in surface waters following the accidental release of 22 000 L of aqueous fire fighting foam in June 2000 into Etobicoke Creek, a tributary of Lake Ontario [85, 124]. PFOS was the predominant PFC observed. Combined concentrations of PFOS, PFHS and PFOA ranged from 0.011 to 2270 pg/L. PFHpA and PFBS were also observed quantitatively. It is interesting to note that PFOS, PFHxS and PFOA were also observed, in lower concentrations, in surface water samples collected upstream of the spill location. Subsequent studies have observed PFCs in a variety of surface waters including rivers [88, 110, 175-178], lakes [114, 121, 166, 179-181] and seas and oceans [86, 95, 112, 165, 175-177, 182]. 

Nitrogen exists in the ocean at oxidation states from -3 to +5. There are three forms of fixed inorganic N NOs", N02 and NH4+. Nitrate is the final oxidation product and is the dominant form of fixed N in the deep ocean. Nitrite generally occurs at very low concentrations because it is an intermediate in the processes of nitrification (NH4+ —> N02 —> NOs") and denitrification (N03 —> N02 —> NO —> N2O —> N2) and so seldom accumulates to a large degree. Concentrations of NH4+ are highly variable but tend to be near the limit of detection in open ocean surface waters. Each of the inorganic forms has a number of manual and automated methods of analysis. We discuss the most widely used below. 

Ammonium is present at very low concentrations (0.03—0.5 iM) in oceanic surface waters, at higher concentrations in coastal and estuarine waters (Sharp, 1983), and at concentrations orders of magnitude higher in sediment pore waters. In seawater, NH4+ exists as the acid base pair NH4+-NH3 (ammonia) the pFC of the pair is 9.3. The methods discussed here measure the sum of NH4+, the form that dominates at the pH of seawater ( <8.3), and NH3, the volatile form that dominates under more alkaline conditions. There are many approaches to measuring NH4+, but we win focus on the two most widely used— phenol-hypochlorite and orthophtal-dialdehyde (OPA). 

Francois, R., Altabet, M. A., Yu, E. F., Sigman, D. M., Bacon, M. P., Frank, M., Bohrmann, G., BareiUe, G., and Labeyrie, L. D. (1997). Contribution of Southern Ocean surface-water stratification to low atmospheric CO2 concentrations during the last glacial period. Nature 389(6654),... 

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