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Measurements of the carbonate system and the transient tracers, CFC-11 and carbon tetrachloride (CCl4), in the Greenland Sea and western Eurasian Basin are used to deduce the sources and magnitude of excess dissolved inorganic carbon in the deep Greenland Sea. The salinity in the deep Greenland Sea has increased during the past 20 years as a result of Arctic Ocean water advecting into the area. From salinity and temperature data the relative amount of advective water below 1500 m is estimated to ∼2% yr−1 between 1982 and 1994. Data from the western Eurasian Basin, collected during the Oden 91 cruise, are used as the advective source waters. A mixing box model is applied to estimate the evolution of CFCs and anthropogenic total dissolved inorganic carbon in the deep waters of the Greenland Sea since preindustrial times. The source functions are the surface water concentrations of CFC-11, CCl4, and total dissolved inorganic carbon CT, which are the result of anthropogenic emission. In order to explain the measured CFC data in the Greenland Sea an annual percent renewal by deep water formation of between 0.5 and 1.2% is needed below 1500 m, corresponding to a mean ventilation of 0.17±0.05 Sv, considering realistic uncertainties in the calculations. This ventilation gives a sequestering of anthropogenic carbon dioxide, which in 1994 equaled 2.4±0.7×1012 g C yr−1.

The biogenic release of halogenated volatile organics from the ocean by natural sources and the biochemical pathways which lead to the production of these substances are not well understood. In this chapter, some of the marine sources are discussed and results are presented and reviewed on the role of vanadium bromoperoxidases from seaweeds in the formation of halomethanes. Further, it will be shown that most of the predominant seaweed species from the North Atlantic, which are also present in the Arctic Ocean, contain bromoperoxidases. In contrast, in members of the Desmarestiales collected in the Weddell Sea (Antarctic) which provide the bulk of the biomass of benthic seaweeds in the Antarctic waters, no bromoperoxidase activity could be detected. The distribu;tion of seaweeds with bromoperoxidase activity is correlated with the seawater concentration of bromoform.

The concentrations of carbon tetrachloride, tetrachloroethylene. 1,1,1-trichloroethane, and bromoform have been determined for Arctic seawater in the Svalbard area in August and September 1980 by a pentane extraction of the seawater followed by glass capillary gas chromatographic separation and electron capture detection. The vertical distributions in a transection across Fram Strait show an inflow of 50 tons/year of carbon tetrachloride, 46 tons/year of tetrachloroethylene, and 114 tons/year of 1,1,1-trichloroethane due to contamination of Atlantic water in the industrial latitudes, and the outflow through the same transection 50, 60, and 129 tons/year, respectively. The uncertainties in these figures are estimated to 50%. Bromoform has a biogenic source in the belts of benthic algae growing in the coastal waters of Svalbard. The mean concentrations for open surface waters were 0.83 (s = 0.17) ng/L, 0.68 (s = 0.23) ng/L, 2.5 (s = 1.8) ng/L, and 9.8 (s = 4.0) ng/L for carbon tetrachloride, tetrachloroethylene, 1,1,1-trichloroethane, and bromoform, respectively. The anthropogenic substances, carbon tetrachloride, tetrachloroethylene, and 1,1,1-trichloroethane, show an undersaturation in the surface water compared with atmospheric northern hemisphere concentrations, which is why the Arctic seawater is thought to act as a sink for atmospheric halocarbons from anthropogenic sources. The biogenic production of bromoform causes an oversaturation in open sea surface waters when compared with the atmospheric background, which is why bromoform is supposed to be a source of atmospheric bromine.