Atlantic Ocean surface waters

Figure 8. UC concentrations in COz extracted from Atlantic Ocean surface waters (16, 40, 44, 56)...

Helmers E. 1996. Trace metals in suspended particulate matter of Atlantic Ocean surface water (40 degrees N to 20 degrees S). Mar Chem 53 51-67. 

Many hydrologic reservoirs can be further subdivided into smaller reservoirs, each with a characteristic turnover time. For example, water resides in the Pacific Ocean longer than in the Atlantic, and the oceans surface waters cycle much more quickly than the deep ocean. Similarly, groundwater near the surface is much more active than deep reservoirs, which may cycle over thousands or millions of years, and water frozen in the soil as permafrost. Typical range in turnover times for hydrospheric reservoirs on a hillslope scale (10-10 m) are shown in Table 6-4 (estimates from Falkenmark and Chapman, 1989). Depths are estimated as typical volume averaged over the watershed area. 

Oceanic circulation. The process of ocean circulation described earlier yields an ocean circulation pattern that results in progressively older deep water as the water passes, in sequence from the Atlantic, Indian, to the Pacific Ocean. Surface water returns relatively quickly to the place of origin for the deep water. 

PFOA observations To evaluate MPI-MCTM model results observational data of PFOA from ship cruises in the Atlantic, Indian and Pacific Oceans were taken from literature (summarised in Yamashita et al (2008)). The data was collected between 2002 and 2006 in a global ocean monitoring initiative. Samples were taken from ocean surface water. Vertical profiles were sampled in the Labrador sea, the Mid Atlantic ocean, the South Pacific ocean and the Japanese sea, where water probes were done at several depths down to 5500 m. The limit of quantification for PFOA was determined as 6 pg/L. 

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. 

North Atlantic Ocean. Surface samples in north Atlantic waters were collected at 20 stations in Tuly-August 1983. The area is influenced mainly by the Gulfstream, the North Atlantic Drift and the much colder East Greenland Current. The surface samples can be grouped into fives areas with common characteristics of temperature, salinity, phosphate and silicate concentrations, Fig. 4 (Kramer, 1986). 

This is reflected in the complexation capacity. Usually a high organic matter content of river and estuarine waters will, together with the colloids in the "dissolved" fraction, result in a high CCqu (100 - 500 nM Cu2+), Fig. 7a. Coastal waters (Fig. 7b), as a result of mixing with seawater, have a lower CCcu (60 - 150 nM Cu2+). Open ocean surface waters of the North Atlantic have a CC u of 20 - 70 nM Cu2+, which in case of low in situ biological activity might be well below this value (Fig. 7c). 

Rau, G.H., Takahashi, T., Desmarais, D.J., Repeta, D.J., and Martin, J. (1992) The relationship between organic matter S13C and [C02(aq)] in ocean surface water data from a JGOFS site in the northeast Atlantic Ocean and model. Geochim. Cosmochim. Acta 56, 1413-1419. 

In our previous investigations of the amounts and distribution of mercury in the surface waters of the northwest Atlantic Ocean, we found a mean total mercury concentration of 7 ng/1. and a range of 6-11 ng/1. (26). Also, we found in open ocean surface waters no significant difference between the mercury concentrations measured directly in pre-acidified seawater ( reactive mercury) and the total mercury determination in the organic free samples. In the work shown in Table II, we also found no significant difference between the reactive mercury determination and the total mercury measurement, which was carried out in approximately one third of the samples. The total mercury measurements appear in the square brackets for the results tabulated in Table II. 

Silicon enters the sea by glacial weathering of rocks in Antarctica and through rivers. Silicon concentrations in rivers very much depend on the geological formation of the respective area. The highest concentrations are found in volcanic areas (350-550 /nutrient concentrations of oceanic surface waters apply also to silicate. Deep water concentrations range from about 25 pmol/L (Atlantic) to 170 jumol/L (Pacific). 

Surface waters in the mid-latitudes are entrained to hundreds of meters of depth ( subtropical mode waters ) (Marsh, 2000 Hanawa and Talley, 2001). They originate as thick winter mixed layers, which are moved to depth and advected from their original formation areas. In the North Atlantic Ocean, this water mass (also referred to as 18 degree water due to its temperature) display elevated CO2 concentrations, indicative of having been out of equilibrium with the atmosphere for several years. By analogy, the subtropical mode waters presumably remove organic compounds from the surface water on similar time scales (Bates et al., 2002). Finally, the turnover of deep lakes also results in mixing of surface layer with its contained compounds into deeper waters as discussed in more detail in Chapter 20. 

Surface water enrichment is the result of aeolian and fluvial inputs, which are thought to be the most important sources of Th to the ocean. Thorinm-232 has been proposed as a link between the radiogenic thorium isotopes and trace metals and anthropogenic pollutants. " While the pathways are very different for the radiogenic thorium isotopes, Th is delivered to the ocean in a fashion similar to many pollutants and trace metals. For example, Guo et found Th distributions in the Gulf of Mexico and off Cape Hatteras in the North Atlantic Ocean agreed well with the general distribution pattern of aluminum. 

Variability of Seawater Vertical sections through seawater showing the distribution of temperature, salinity, and oxygen for the Pacific Ocean and Western Atlantic Ocean are shown in Figures 21.3 and 21.4. The global variability of natural seawater and its effects on corrosion have been reviewed in particular with respect to seasonal variation of temperature, salinity, oxygen and pH in the Pacific surface water. Data is also given on... 

Conventional T-S diagrams for specific locations in the individual oceans are shown in Fig. 10-4. The inflections in the curves reflect the inputs of water from different sources. The linear regions represent mixing intervals between these core sources. For example, in the Atlantic Ocean the curves reflect input from Antarctic Bottom Water (AABW), North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AIW), Mediterranean Water (MW), and Warm Surface Water (WSW). 

Figure 3. Time series of nitrate (Slagle and Heimerdinger 1991) and dissolved, particulate, and total in surface water at 47°N, 20°W (Atlantic Ocean) in April-May 1989. activity calculated as 0.0686 salinity (Chen et al. 1986). The production of biogenic particles during the bloom enhances the scavenging of Th, resulting in growing disequilibrium with time due to sinking of particles.

DDT and DDE observations Iwataetal(1993)determinedconcentratonsofDDT in in the air and surface water from various oceans in 1989-1990. The routes of the ship cruises among others covered the Chukchi Sea, Bering Sea, Gulf of Alaska, North Pacific, East China Sea, South China Sea, North Atlantic ocean, Bay of Bengal, and the Southern ocean. 

Lovelock and co-workers [228,229] determined methyl fluoride, methyl chloride, methyl bromide, methyl iodide, and carbon tetrachloride in the Atlantic Ocean. This shows a global distribution of these compounds. Murray and Riley [230,231] confirmed the presence of carbon tetrachloride, and also found low concentrations of chloroform and tri- and tetrachloroethylene in Atlantic surface waters. 

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). 

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