Ocean vertical profile

Aluminum is the best illustration of a trace metal with a scavenged-type distribution in the oceans. The major external input of aluminum is from the partial dissolution of atmospheric dust delivered to the surface ocean. Vertical profiles in the Mediterranean, the North Atlantic, and the North Pacific are presented in Figure 4. Extremely elevated concentrations of dissolved aluminum are observed in the Mediterranean Sea (Hydes et al., 1988), a region that receives a high atmospheric input of dust. Concentrations in... 

Vertical profiles and surface concentrations of DDT dissolved in the ocean were measured by Tanabe and Tatsukawa (1983). Water samples for depths down to 5000 m were taken on three cruises of the Ocean Research Institute, University of Tokyo and on a cruise by the University of Fisheries, Tokyo. The cruises were carried out between 1976 and 1981 in the Western Pacific, Eastern Indian and Antarctic oceans. 

Fig. 3.9 Vertical profiles of DDT concentration [ng/L] in the Pacific ocean close to Japan (A),(B), in the Indian ocean (E), and in the Antarctic ocean (F). Model results in comparison with observations from Tanabe and Tatsukawa (1983).

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. 

Vertical profiles from different ocean regions differ significantly from each other. In the Labrador Sea (Figure 3.16a) PFOA concentrations are 50 pg/L at the surface for both model results and observations. For AOl and A02 modelled profiles are almost identical, while observed profiles behave differently. Concentrations in water sample at AOl are relatively constant throughout depth, except for subsurface water, where PFOA concentration decreases, and water below 2000 m in which concentrations increase. Modelled concentrations, as well as observed ones at A02, decrease until 500 m, and remain constant down to 2000 m. In waters below 2000 m PFOA concentration increases for observations, but decreases in the model results. Yamashita et al (2008) suggest that water masses from the surface down to 2000 m were well mixed due their convective formation. The subsurface is explained... 

Model results in seawater are in good agreement with observational data of PFOA. Most differences can be attpageributed to deficiencies of the emission scenario. Despite this fact, the difference between model results and observational data are due to the limited horizontal and process resolution and the fact that the physical parameters of the model (temperature, surface pressure, vorticity or divergence of the wind velocity field) were not relaxed to observational data. Regarding these limitations, in particular individual vertical profiles compare quite well with observations. This study underlines the importance of the ocean as a transport medium of PFOA. The contribution of volatile precursor substances to long-range transport needs to be assessed. 

Data from GEOSECS, TTO, BATS, and HOTS and other major oceanographic research projects, such as the WOCE (World Ocean Circulation Experiment) are available online. The GEOSECS, TTO, and WOCE datasets are part of the Java Ocean Atlas, which provides a graphic exploration environment for generating vertical profiles, cross-sections, and property-property plots. Many of the data presented in this text were obtained from this source. 

Longitudinal profiles in the Atlantic Ocean at about 25°W. (a) Potential temperature (°C), (b) salinity, (o) potential density (0 dbar), (d) potential density (4000 dbar), and (e) dissolved oxygen ( j,mol/kg). Source-. After Talley, L. (1996). Atlantic Ocean Vertical Sections and datasets for selected lines. http /sam.ucsd.edu/vertical.sections/Atlantic.html. Scripps Institute of Oceanography, University of California - San Diego. Data are from WOCE hydrographic program. (See companion website for color version.)... 

Elements that are not biolimiting have quite different vertical concentration profiles. Thus, the shapes of vertical concentration profiles can be used to infer the most important bio-geochemical processes acting on the chemical of interest. In this chapter and the next, we will explore several sets of vertical profiles for nitrogen, phosphorus, and silicon, obtained from different parts of the world s ocean. In Chapter 11, we will investigate the vertical profiles of the micronutrients, such as iron and zinc. 

The O2 content of the surface waters is lower at mid-latitudes because of higher temperatures, which lead to lower gas solubility. As shown in Figure 10.1a, the ther-mocline is characterized by a concentration minimum that increases in intensity from the Atlantic to the North Pacific. Note that the O2 minimum is less pronounced in the vertical profile from 45°S as compared to 9°N in the Atlantic Ocean because of close proximity to the site of AABW formation. Mid-water phosphate and nitrate maxima... 

The influence of river water inputs on trace metal distributions is illustrated in Figure 11.17c, which shows that the surface-water concentration of dissolved Mn in the Pacific Ocean decreases with increasing distance from the California coast. The vertical profile measured in the coastal zone (Figme 11.17b) exhibits a strong surface enrichment characteristic of scavenged trace elements. A similar vertical gradient is seen in the... 

Upper panels show vertical profiles of manganese in the North Pacific Ocean at (a) an open-ocean station, (b) a coastal station, and (c) the Mn content of surface water with increasing distance from the California coast. Note the tenfold scale difference in concentration between these diagrams. Source From Landing, W. M., and K. W. Bruland (1980). Earth and Planetary Sciences Letters, 49, 45-56. 

Vertical profiles of (a) excess He and (b) dissolved manganese at two sites in the North Pacific Ocean. The data represented by the solid circles were obtained from water located directly over the crest of the East Pacific Rise at 21 °N. Source From Broecker, W. S., and T.-H. Peng (1982). Tracers In the Sea, Lamont-Doherty Geological Observatory, p. 229. See Broecker and Peng (1982) for data sources. 

Particulate matter that reaches the seafloor becomes part of the blanket of sediments that lie atop the crust. If bottom currents are strong, some of these particles can become resuspended and transported laterally until the currents weaken and the particles settle back out onto the seafloor. The sedimentary blanket ranges in thickness from 500 m at the foot of the continental rise to 0 m at the top of the mid-ocean ridges and rises. Marine scientists refer to this blanket as the sedimentary column. Like the water column, the sediments contain vertical gradients in their physical and chemical characteristics. Similar to the vertical profile convention used in the water column, depth in the sediments is expressed as an increasing distance beneath the seafloor. 

In the epilimnion/hypolimnion two-box model the vertical concentration profile of a chemical adopts the shape of two zones with constant values separated by a thin zone with an abrupt concentration gradient. Often vertical profiles in lakes and oceans exhibit a smoother and more complex structure (see, e.g., Figs. 19.1a and 19.2). Obviously, the two-box model can be refined by separating the water body into three or more horizontal layers which are connected by vertical exchange rates. 

Another procedure is based on the measurement of the radioactive isotope radon-222 (half-life 3.8 days), the decay product of natural radium-226. At the bottom of lakes and oceans, radon diffuses from the sediment to the overlying water where it is transported upward by turbulence. Broecker (1965) was among the first to use the vertical profile of 222Rn in the deep sea to determine vertical turbulent diffusivity in the ocean. 

Figure 6. Some vertical profiles of nC in the North Pacific Ocean...

We measured H202 vertical profiles in Lake Erie (14, 18) and noted the similarity with oceanic profiles (23, 24). The major difference is the depth to which H202 is mixed in oceanic environments. To emphasize the effect of solar radiation and wind speed on the distribution of H202 in the epilimnion, we measured four vertical profiles of H202 concentration and temperature in Jacks Lake on 4 days, September 11-14, 1990, all at 4 00 p.m. 

Below a depth of around 1000 m, there is little variation in the concentration of DOC. This may be true as well for DON and DOP, but the increasingly irregular profiles at lower concentrations of DON and DOP preclude a definitive interpretation. Although concentrations of DOP are rather low in deep ocean waters (=0.02pmolkg 1), the irregularity in the vertical profiles of DON and DOP in Figure 11.2 is most likely attributable to the statistically small number of observations—only around two observations per depth interval between 2000 m and 5000 m. 

Figure 12.4 Vertical profiles of the Group 3 elements in the North Pacific Ocean, including selected actinides. Data sources Sc (Spencer et al., 1970), Y, La, Pr-Lu (Zhang and Nozaki, 1996), Ce (Piepgras and Jacobsen, 1992), Ac (Nozaki, 19 84), 232Th (Roy-Barman et al., 1996), U (Chen et al., 1986) and 241Am (Livingston et al., 1983). Relative species abundance is shown to the right of each figure in descending order.

Figure 12.6 Vertical distributions of Group 4 elements in the North Pacific. Data sources Ti (Orians et at., 1990), Zr (McKelvey and Orians, 1993) and Hf (Godfrey et at., 1996). The Hf distribution (dotted line) was calculated based on the average Atlantic Ocean Zr/Hf ratio of Godfrey et at. (1996) and the Pacific Ocean Zr profile of McKelvey and Orians (1993).

The vertical profile of DMS in marine air was first determined by Ferek et al (12), over the tropical Atlantic ocean. They found that under stable meteorological conditions, the mixing depth of DMS was about 1 km, with a rapid decline in concentration above this altitude. This distribution was considered consistent with the chemical lifetime of a few days predicted by... 

Similar vertical profiles have been reported in subsequent aircraft studies. Luria et al. (2Q) measured DMS concentrations over the Gulf of Mexico averaging 27 ppt in the marine boundary layer, 7 ppt in boundary layer of continental origin, and <3 ppt in the free troposphere. Van Valin et al. (16) reported highly variable DMS levels over the north Atlantic Ocean in the pollutant plume from the Northeastern U.S., measured in the vicinity of Boston. Those workers also reported a vertical profile from Bermuda which was virtually identical to the stable case of Ferek et al. (15) off Barbados. 

The measurements carried out by the Centre des Faibles Radioactivity (CFR) in France (4.91 are based on the determination of the vertical profile of DMS concentrations in the first few meters above the ocean. These data were obtained during the oceanographic mission OCEAT 1 in the Pacific ocean in November 1982. A sharp decrease of the concentration was observed between the surface and 20 m height from which the residence time could be estimated by making the following assumptions,... 

Fig. 4 Typical vertical profiles of DMS and DMSPt in different regions of the Indian Ocean...

Several vertical profiles through the ocean showed H2 contents to decrease with depth to equihbrium values compared with surface air. These profiles also showed distinct layers slightly enriched in H2 in the oceans. 

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