Framvaren and the Black Sea - Similarities and differences

The following determinations in the Norwegian fjord Framvaren and the Black Sea have been compared: carbon-14, carbon-13, alkalinity, total dissolved inorganic carbon, sulfide, tritium (HTO), trace metals, silica, ammonium and phosphate. The historical development of the two anoxic basins is quite different. The carbon-14 age of the total inorganic dissolved carbonate in the deep water is 2000 years in the Black Sea, but only 1600 in Framvaren. The fresh water supply and composition are different. The rivers entering the Black Sea have a high alkalinity, but the river input and runoff to Framvaren has a very low alkalinity. The alkalinity, carbonate and sulfide concentrations in the anoxic waters below the chemoclines are much higher in Framvaren. This is mainly an effect of the different surface to volume ratios. The difference in carbon-13 (-8 parts per thousand for the Black Sea deep water, -19 parts per thousand in the Framvaren bottom water) is mainly due to the smaller imprint of the decomposition of organic matter on the Black Sea deep water. The concentration of trace metals in the particulate form are about the same in the deep water.. About 76% of the molybdate in seawater is lost in the sulfidic water of Framvaren, and about 82-96% of the molybdate carried into the Black Sea by the Bosporus undercurrent is lost in the deep water. The relation between silica, ammonium and phosphate can be understood if part of the ammonium is being removed by denitrification, a process that most likely has been going on for thousands of years.