Latitudinal fractionation

Argell C, OklaL, LarssonP, Backe C, Wania F (1999) Evidence of latitudinal fractionation of polychlorinated biphenyl congeners along the Baltic Sea region. Environ Sci Technol 33 (8) 1149-1156... 

The impact of deposition on global distribution has been noted for the CFC replacements hydro-chlorofluorocarbons (HCFCs), the chlorinated solvents tetrachloroethene (PCE), and trichloro-ethene (TCE), as these compounds undergo gas phase oxidation and photochemical degradation, resulting in the formation of carbonyl halides (e.g., CCI2O) and haloacetyl halides (e.g., bromo-, chloro-, and fluoroacetates). As these compounds are polar and water soluble, they are transported via aerosols, rain, and fog, which impacts their tropospheric lifetime and depositional fluxes (Rompp et al., 2001 de Bmyn et al., 1995). It is not clear whether and to what extent there is evidence of latitudinal fractionation of these compounds. 

Sobek, A. and O. Gustafsson 2004. Latitudinal fractionation of polychlorinated biphenyls in surface seawater along a 62 degrees N-89 degrees N transect from the southern Norwegian Sea to the North Pole area. Environmental Science Technology 38(10) 2746-2751. 

Fig. 3.17 Vertical and latitudinal distribution of PFOA mass in the global oceans [t] (left), 12/2004, fraction of mass bound to organic matter [%] (right), 06/2004.Upper panels KOC115, lower panels KOC11500.

The abyssal clays are composed primarily of clay-sized clay minerals, quartz, and feldspar transported to the siuface ocean by aeolian transport. Since the winds that pick up these terrigenous particles travel in latitudinal bands (i.e., the Trades, Westerlies, and Polar Easterlies), the clays can be transported out over the ocean. When the winds weaken, the particles fell to the sea siufece and eventually settle to the seafloor. Since the particles are small, they can take thousands of years to reach the seafloor. A minor fraction of the abyssal clays are of riverine origin, carried seaward by geostrophic currents. Despite slow sedimentation rates (millimeters per thousand years), clay minerals, feldspar, and quartz are the dominant particles composing the surface sediments of the abyssal plains that lie below the CCD. Since a sediment must contain at least 70% by mass lithogenous particles to be classified as an abyssal clay, lithogenous particles can still be the major particle type in a biogenous ooze. 

Seasonal and interannual trends in atmospheric carbon dioxide concentrations reported as mole fraction in dry air. (a) Monthly mean values at Mauna Loa Observatory, Hawaii. Data are also presented as 6-month running average to eliminate the seasonal effects and (b) three-dimensional representation of latitudinal distributions of monthly mean values. Source After P. Tans and T. Conway, NOAA/ESRL Global Monitoring Division (www.esrl.noaa.gov/gmd/ccgg/trends). (See companion website for color version.)... 

Figure 9. Latitudinal variations in potential production of carbonyl sulfide in the ocean filled circles open ocean estimated using apparent quantum yields for Pacific Ocean provided by Weiss et al. [189] and open ocean areas [8, 173] open circles coastal photoproduction estimated using average coastal AQYs determined by Zepp and An-dreae [193] and coastal ocean areas [67,173]. Integrated production was 58.3 Gmol yr for the open ocean and 12.8 Gmol yr for coastal regions, uncorrected for cloud cover. Light attenuation by clouds reduces UVR by approximately 30-40% on average [103]. A substantial fraction of the COS is hydrolyzed before it can escape to the atmosphere [141,...

Continental glaciation exerts effects on the isotopic composition of the oceans arising from isotopic fractionation in the meteoric cycle. High-latitudinal precipitation is depleted in the heavy stable isotopes relative to ocean water so that when continental glaciers grow, the light... 

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