Fatty acids in recent sediments in the St. Lawrence estuary

Surface sediments along the Rimouski section in the St. Lawrence estuary were sampled at the surface and at 10 cm depth. Fatty acids were extracted and analysed. Saturated and unsaturated fatty acid contents at the two depths vary with the nature of the sediments. The clay sediments rich in organic matter contain more fatty acids than the corresponding sand or gravel. Unsaturated fatty acids were more abundant in the surface sediments. Some iso- and anteiso-odd carbon fatty acids were detected in the sediments; these acids could indicate a microbial activity. Correlation is made with the fatty acid contents of the water column together with the surface microlayer of the estuarine water.