L. Falkowska et H. Piekarek-jankowska, Submarine seepage of fresh groundwater: disturbance in hydrological and chemical structure of the water column in the Gdansk Basin, ICES J MAR, 56, 1999, pp. 153-160
Anomalies observed in the thermohaline and chemical stratification of the w
ater column in the Gdansk Basin indicate a decline in salinity and an incre
ase in temperature in the near-bottom layer. We suggest that these disturba
nces were caused by fresh groundwater drainage from Cretaceous water-bearin
g horizons. Turbulent convection zones are found over the seepage area, wit
h a Rayleigh thermohaline number in the range 10(15)-10(16). Owing to very
strong thermohaline convection, the pycnocline is forced and an intrusion o
f more saline water ascends into the less saline surface layers. Simultaneo
us with the observed convection effects, a redistribution of the accumulate
d nutrients below the pycnocline can be seen in the water column and an imp
rovement of oxygen conditions in the near-bottom water. (C) 1999 Internatio
nal Council for the Exploration of the Sea.