Oxygen depletion in a Faroese sill fjord

Skálafjørdur is a sill fjord with formation of a stagnant bottom layer during each summer. In the summer of 1985 oxygen concentrations were observed to be much lower than previously found in the bottom water. On the basis of historical data it is argued that this was an unusal occurence and not a common phenomenon, not previously observed due to inadquate sampling. Using temperature measurements the mixing rate between bottom water and water above sill level is estimated, and it is shown that the vertical flux of oxygen due to mixing is comparable to the biological consumption rate of oxygen, using a very simple model. It is also argued that the mixing rate was considerably smaller than usual during the summer of 1985, thus explaining part of the anomaly, but no firm conclusions could be drawn from this model on the possibility of increased oxygen consumption due to pollution.