The Surface Waters Acidification Project Palaeolimnology Programme: modern diatom/lake-water chemistry data-set

In 1983, when the Surface Waters Acidification Programme (SWAP) was announced, we were asked to design and implement a palaeolimnology sub-project involving scientists from Sweden, Norway, and the UK. Our aim was to reconstruct the acidification history of a range of sites in the three countries and to identify and evaluate the various alternative causes of lake acidification. The results of the project have been published recently (Battarbee et al. 1990, Renberg and Battarbee 1990). Although a comprehensive range of palaeolimnological methods and approaches was used in the study we recognised diatom analysis as central to the entire project. We consequently committed considerable effort to improving our diatom methodology and we were especially concerned with the pursuit of a common approach to diatom taxonomy and pH reconstruction. This effort centred on the creation and analysis of a large data-set of surface-sediment diatom assemblages and associated environmental variables from 170 sites representing the full range of lake types in the acid-sensitive and acidified regions of the three countries

Holocene tidal levels and sedimentation rates using a diatom-based palaeoenvironmental reconstruction: The Tees estuary, northeastern England

An established diatom-based tidal level transfer function is used in combination with the present-day relationship between sedimentation rate and altitude to reconstruct Holocene tidal sediment accretion for the Tees estuary, northeastern England. The results from five cores reveal two periods of enhanced-sedimentation, the earlier of which (8000-6000 cal. BP) is related to relatively rapid sea-level rise and increasing tidal range. The later phase of increased tidal sedimentation also reflects an enhanced marine influence after c. 3000 cal. BP, but may also be attributed to climate- and human-induced changes in terrestrial sediment flux to the coastal zone. Comparison of the reconstructed sediment accretion rates with actual rates calculated from radiocarbon and luminescence dated sedimentary horizons reveals that this diatom-based approach overestimates sediment accretion by a factor of three. This overestimation is considered to be due to the contemporary sediment flux being an inappropriate analogue for the mid- to late Holocene rather than to any significant methodological flaws in the approach.link_to_subscribed_fulltex