An integrated lake-catchment approach to reconstruct land use changes and pollution history at Aqualate Mere, Central England, UK

This paper uses a lake-catchment approach to reconstruct land use changes and pollution history at Aqualate Mere in central England. The Mere is a shallow lake (max water depth c. 1m) and is designated a Site of Special Scientific Interest and National Nature Reserve. Formed in a kettle hole since the last glacial period, it holds c. 11 m depth of sediment and regionally provides a unique archive of Holocene environmental change. Radiocarbon, Cs-137 and Pb-210 dating and the distribution of Spheroidal Carbonaceous Particles (SCPs) suggest that the upper 5 metres of sediment accumulated over the past three millennia with an acceleration of sedimentation in the last 200 years. In this paper we use multi-proxy data to reconstruct and investigate the influence of human activities (namely agriculture and metallurgy) on the Mere and its catchment. High resolution pollen and non-pollen palynomorph data provides evidence for woodland clearance and agriculture which intensified during the Roman period, whilst more recent changes match historical documentary evidence of landscaping, tree plantations and industrial pollution. High percentages of Anabaena, a cyanobacteria, and changes in diatom populations suggest that such activities promoted more eutrophic conditions in the Mere; an interpretation supported by the likely increase in bacterial magnetite as reflected in time-synchronous changes in mineral magnetic signatures. Sediment chemistry also provides evidence of regional lead pollution during the Late Bronze Age, the Roman period and the last c. 200 years. Mineral magnetic data and radionuclide signatures of potential catchment sources and Mere sediments proved to be relatively poor discriminators of catchment sources suggesting that, except for the past 200 years, the Mere sediment was autochthonous and perhaps dominated in recent times by a high atmospheric pollution load. The results of our investigation suggest that human impact on the Mere has been considerable since late prehistoric times. A detailed appraisal of both catchment sources and lake sediments is important to understand the interplay of human activities on long term records of environmental change and to fully understand the external and internal processes that can impact on a lake which can then be used to develop effective catchment management strategies