Palaeoecological Study of Llyn Padarn (2009)

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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.

Identification

Dynodydd
Identifier
NRW_DS112214
Teitl Amgen
Alternative Title
  • Astudiaeth balaeoecolegol o Lyn Padarn
Laith Metadata
Metadata Language
English
Lineage

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.
Dyddiad cyfeirnod y set ddata (Cyhoeddiad)
Dataset Reference Date (Publication)
2010-05-01
Perchennog
Owner
  Natural Resources Wales (NRW)
Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales
http://naturalresources.wales/?lang=en
Cychwynnwr
Originator
  University College London.
UCL (University College London) Pearson Building, Gower Street, London, WC1E 6BT, England
http://www.ensis.ucl.ac.uk/
Cychwynnwr
Originator
  Ensis Ltd
Not Provided
Not Provided
 

Extent

Extent

Hyd
Geographic Extent
Wales (WLS)
Hyd
Geographic Extent
GWYNEDD - GWYNEDD
N
W
E
S
Map representing the geographic extent of the dataset


 

Vertical Extent

Maint Fertigol
Vertical Extent

Gwerth lleiaf
Minimum value (metres)
105
Gwerth uchaf
Maximum value (metres)
105
System Gyfeirio Cydlynu Fertigol
Vertical CRS
 
 

Distribution

Fformat - Math a Disgrifiad
Format Type and Description
  • Documents ()

    Specification

    [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

 

Quality

Ansawdd Data
Data quality

Cwmpas Ansawdd
Quality Scope
Dataset
Dataset
Cydymffurfiad
Conformity
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
Explanation

This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
Degree
false
Lineage

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.
 

Keywords

Allweddair
Keywords

GEMET - INSPIRE themes, version 1.0
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2008-06-01
Code
geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme

Allweddair
Keywords

NRW Thesaurus
  • palaeoecology
  • diatoms
  • chrysophycota
  • eutrophication
  • sediments
  • pollution (see also specific types of pollution eg. oil pollution)
  • environmental change
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2023-12-31
Code
geonetwork.thesaurus.local.theme.converted_nrw-keywords
 

Spatial Reference System

Code
British National Grid (EPSG::27700)
 

Content

Gwybodaeth Cynnwys
Content Information

Proffil CNC
NRW Profile

Elfennau CNC
Custom Elements

NRW Related Title

Palaeoecological study of Llyn Padarn
 

Constraints

Constraints

Limitations on Public Access and Use

Math o Gyfyngiad
Restriction type
Other restrictions
Other restrictions
 

Access Constraints Directive

Limitations
no limitations
 

Access Constraints Text

Other constraints

There are no access restrictions on this data. NRW may release, publish or disseminate it freely.
 

Use Constraints

Cyfyngiadau Defnyddio
Use constraints type
Other restrictions
Other restrictions
Other constraints

© 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.
 
 
 

Metadata

Metadata

Dynodydd Ffeil
File Identifier
4f4c4942-4343-5764-6473-313132323134 XML
Laith Metadata
Metadata Language
English
Math o adnodd
Resource type
Dataset
Dataset
Dyddiad Metadata
Metadata Date
2024-05-30T14:10:47.11Z
Enw Safonol Metadata
Metadata Standard Name
NRW
Fersiwn Metadata
Metadata Standard Version

1.0

Pwynt Cyswllt
pointOfContact
  Natural Resources Wales (NRW)
Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales
http://naturalresources.wales/?lang=en
 
 

Publishing Body

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