4f4c4942-4343-5764-6473-313132323134 English Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2024-05-30T14:10:47.11Z NRW 1.0 wel British National Grid (EPSG::27700) Palaeoecological Study of Llyn Padarn (2009) Palaeoecological Study of Llyn Padarn (2009) Astudiaeth balaeoecolegol o Lyn Padarn 2010-05-01 NRW_DS112214 Llyn Padarn is designated as a Site of Special Scientific Interest (SSSI) for several reasons including its populations of Arctic charr and floating water-plantain. However, there have been several concerns of the water quality, owing to the decline in adult charr population and the occurrence of the blue-green algal bloom in 2009. In light of this, it was necessary to assess the recent environmental change that has occurred in the lake. The aim of this project is to sample and analyse a lake sediment core from Llyn Padarn and relate the findings to chemical and nutrient changes over time and known events in the lake's history. Palaeolimnological methods offer a means of reconstructing the environmental history of standing waters by studying subfossil fragments of the biota preserved in the lake sediments. The project aims to reconstruct the environmental history of Llyn Padarn over approximately the last century using diatoms, with particular attention to the eutrophication history of the site. The study focuses on diatom remains in sediment cores, and also includes the application of an existing diatom-total phosphorus (TP) model to reconstruct the nutrient history of the lake. In addition to this, X-ray fluorescence analysis was carried out to assess down core changes in chemical composition, with a particular focus on iron, copper and P. The analysis of a dated sediment core collected from Llyn Padarn in 2009 (PADA2) was used to assess environmental change over the last 100-150 years. The data was also used to reconstruct the environmental history of Llyn Padarn over approximately the last century with particular attention to the eutrophication history of the site. Diatom analysis of only three samples from an undated core taken from the lake in August 2004 showed that the diatom assemblage shifted from species typically associated with nutrient-poor waters towards those associated with more productive systems. This study builds on this earlier work by analysing a new sediment core at a higher resolution and providing a chronology to determine the timing and rates of change. The study feeds into ongoing monitoring at Llyn Padarn to determine the trophic status of the lake and the health of the Arctic charr population. Llyn Padarn is designated as a Site of Special Scientific Interest (SSSI) for several reasons including its populations of Arctic charr and floating water-plantain. However, there have been several concerns of the water quality, owing to the decline in adult charr population and the occurrence of the blue-green algal bloom in 2009. In light of this, it was necessary to assess the recent environmental change that has occurred in the lake. The aim of this project is to sample and analyse a lake sediment core from Llyn Padarn and relate the findings to chemical and nutrient changes over time and known events in the lake's history. Palaeolimnological methods offer a means of reconstructing the environmental history of standing waters by studying subfossil fragments of the biota preserved in the lake sediments. The project aims to reconstruct the environmental history of Llyn Padarn over approximately the last century using diatoms, with particular attention to the eutrophication history of the site. The study focuses on diatom remains in sediment cores, and also includes the application of an existing diatom-total phosphorus (TP) model to reconstruct the nutrient history of the lake. In addition to this, X-ray fluorescence analysis was carried out to assess down core changes in chemical composition, with a particular focus on iron, copper and P. The analysis of a dated sediment core collected from Llyn Padarn in 2009 (PADA2) was used to assess environmental change over the last 100-150 years. The data was also used to reconstruct the environmental history of Llyn Padarn over approximately the last century with particular attention to the eutrophication history of the site. Diatom analysis of only three samples from an undated core taken from the lake in August 2004 showed that the diatom assemblage shifted from species typically associated with nutrient-poor waters towards those associated with more productive systems. This study builds on this earlier work by analysing a new sediment core at a higher resolution and providing a chronology to determine the timing and rates of change. The study feeds into ongoing monitoring at Llyn Padarn to determine the trophic status of the lake and the health of the Arctic charr population. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en University College London. UCL (University College London) Pearson Building, Gower Street, London, WC1E 6BT, England s.patrick@geog.ucl.ac.uk http://www.ensis.ucl.ac.uk/ Ensis Ltd Not Provided Not Provided Not Provided Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Atmospheric conditions GEMET - INSPIRE themes, version 1.0 GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme palaeoecology diatoms chrysophycota eutrophication sediments pollution (see also specific types of pollution eg. oil pollution) environmental change NRW Thesaurus NRW Thesaurus 2023-12-31 geonetwork.thesaurus.local.theme.converted_nrw-keywords SeaDataNet Parameter Discovery Vocabulary SeaDataNet Parameter Discovery Vocabulary 2021-01-06 geonetwork.thesaurus.external.theme.rdf+xml Integrated Public Sector Vocabulary Integrated Public Sector Vocabulary 2013-04-03 geonetwork.thesaurus.external.theme.subjects NRW SMNR Vocabulary NRW SMNR Vocabulary 2023-12-27 geonetwork.thesaurus.local.theme.converted_nrw-smnr-keywords There are no access restrictions on this data. NRW may release, publish or disseminate it freely. no limitations © CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose. English biota SeaVoX Vertical Co-ordinate Coverages SeaVoX Vertical Co-ordinate Coverages 2021-01-06 Wales (WLS) GWYNEDD - GWYNEDD -4.16793966 -4.08890282 53.08941845 53.15060598 2009-09-01 2009-09-01 105 105 Palaeoecological study of Llyn Padarn Documents [A] Published report (CCW Contract Science Report No 918) - paper and electronic version (PDF & MS Word) Ffynnon Reference: DCT-10-088698 [B] Raw data - Excel [C] Photo of core - hard copy Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 This dataset has not been assessed for conformance to the referenced INSPIRE regulation. false Core Collection A single sediment core was collected from the deep basin of the lake using a Glew gravity coring device. The coring location was located by a hand-held echo sounder and recorded by GPS. Extrusion and core description The core was extruded in the field at 0.5 cm intervals to a depth of 20 cm and at 1 cm intervals thereafter. Any visible stratigraphic changes were noted and the core was photographed. The percentage dry weight (Percent DW) which gives a measure of the water content of the sediment, percentage loss on ignition (Percent LOI) which gives a measure of the organic matter content, and percentage carbonate were determined in the laboratory on every sample by standard techniques. Wet density was measured on selected samples by filling and weighing a 2 cm3 brass vial with sediment. Radiometric Dating Standard reliable methods of establishing a chronology for sediment cores was used for radiometric dating techniques. Sediment samples from the Llyn Padarn core (coded PADA2) were analysed for 210Pb, 226Ra, 137Cs and 241Am by direct gamma assay in the Bloomsbury Environmental Isotope Facility (BEIF) at University College London using either an ORTEC HPGe GWL series well-type, or an ORTEC HPGe LOAX series planar-type, coaxial low background intrinsic germanium detector. 210Pb was determined via its gamma emissions at 46.5keV, and 226Ra by the 295keV and 352keV gamma rays emitted by its daughter isotope 214Pb following three weeks storage in sealed containers to allow radioactive equilibration. 137Cs and 241Am were measured by their emissions at 662kev and 59.5kev. The absolute efficiencies of the detector were determined using calibrated sources and sediment samples of known activity. Corrections were made for the effect of self-absorption of low energy gamma rays within the sample. Core Collection A single sediment core was collected from the deep basin of the lake using a Glew gravity coring device. The coring location was located by a hand-held echo sounder and recorded by GPS. Extrusion and core description The core was extruded in the field at 0.5 cm intervals to a depth of 20 cm and at 1 cm intervals thereafter. Any visible stratigraphic changes were noted and the core was photographed. The percentage dry weight (Percent DW) which gives a measure of the water content of the sediment, percentage loss on ignition (Percent LOI) which gives a measure of the organic matter content, and percentage carbonate were determined in the laboratory on every sample by standard techniques. Wet density was measured on selected samples by filling and weighing a 2 cm3 brass vial with sediment. Radiometric Dating Standard reliable methods of establishing a chronology for sediment cores was used for radiometric dating techniques. Sediment samples from the Llyn Padarn core (coded PADA2) were analysed for 210Pb, 226Ra, 137Cs and 241Am by direct gamma assay in the Bloomsbury Environmental Isotope Facility (BEIF) at University College London using either an ORTEC HPGe GWL series well-type, or an ORTEC HPGe LOAX series planar-type, coaxial low background intrinsic germanium detector. 210Pb was determined via its gamma emissions at 46.5keV, and 226Ra by the 295keV and 352keV gamma rays emitted by its daughter isotope 214Pb following three weeks storage in sealed containers to allow radioactive equilibration. 137Cs and 241Am were measured by their emissions at 662kev and 59.5kev. The absolute efficiencies of the detector were determined using calibrated sources and sediment samples of known activity. Corrections were made for the effect of self-absorption of low energy gamma rays within the sample.