A STUDY OF THE COMPOSITION AND DISTRIBUTION OF LIGNIN IN RESUSPENDED AND PERMANENTLY SUSPENDED PARTICLES IN THE RIVER TAMAR ESTUARY

The composition and distribution of lignin in the permanently suspended and resuspended material of the Tamar Estuary have been investigated by separating particles on the basis of settling characteristics. Lignin was determined using the diagnostic phenols formed by copper oxide oxidation. Samples were collected over a tidal cycle at different depths at a single location and over a 30 km transect 1of the estuary at a constant depth. Summed values of lignin oxidation products in permanently suspended materials ranged from 0·90 to 10·49 mg, normalized to particulate organic carbon. These values are considerably higher than the range 0·22 to 3·87 mg measured in material resuspended as a result of tidal action. The different values reflect the relative buoyancy of the lignin-bearing materials. Ratios of the various lignin components suggest that the permanently suspended fraction contains a significant proportion of degraded angiosperm tissues, while in the resuspended fraction a component of degraded gymnosperm material is indicated. © 1991.