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Dataset information

SWAP dataset

EDDI dataset codeSWAP
Dataset typepH
Number of samples178
Collection date1979 - 1987
ContributorThe SWAP Participants
ContactsRick Battarbee, John Birks, Steve Juggins

The Surface Waters Acidification Programme (SWAP) calibration training set included initially 178 surface sediment diatom assemblages and the associated environmental variables from 170 sites. Data-screening reduced these to 167 lakes, which using weighted averaging give superior results in terms of lowest root mean squared errors of prediction in cross-validation (Birks et al. 1990a; Birks et al. 1990b). The refined diatom/water chemistry training set used within the SWAP project is derived from five regional datasets (number of samples in parentheses) from Sweden (30), Norway (51), Scotland (60), Wales (32) and the English Lake District (5). These sites represent upland lakes in Britain and both upland and lowland lakes in Scandinavia with a bias towards acidic waters. Using gravity or a piston corer, surface sediment samples were usually taken from the deepest point in each lake and in all cases the top 0.5 cm was used for diatom preparation. A total of approximately 500 diatom valves per sample were counted. As a result of the considerable variation in taxonomic and nomenclatural usage between diatomists in different laboratories a programme of taxonomic harmonisation was undertaken to construct a common diatom dataset (Munro et al. 1990). The development and application of the SWAP training set is very well documented in the publications cited below and in many subsequent projects which have applied SWAP training set in other contexts or compared its performance with that of new training sets.

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  • Summary of environmental data for this dataset:
    VariableUnitsNMinMaxMean
    Alkalinity畫q/l160090357.7
    Aluminium (labile)痢/l52233351.2
    Aluminium (monomeric)痢/l201446989.8
    Aluminium (total)痢/l17312802131
    Calcium畫q/l1756.17938109
    Chloride畫q/l17510.41160187
    Conductivity猶/cm1777.3715444.5
    Iron痢/l1393.5838143
    Magnesium畫q/l1747.8133767.5
    Manganese痢/l1361.560254.9
    Maximum depth of lakem17716115.9
    Nitrate痢/l1250.691.510.5
    pHpH units1784.337.255.59
    Potassium畫q/l1742.0154.19.8
    Silicamg/l1370.17971.33
    Sodium畫q/l14416.51004172
    Sulphate畫q/l17518.7352107
    Total nitrogen痢/l11710982272
    Total organic carbonmg/l1480.12173.94
    Total phosphorus痢/l1253111.4
    Water depth of diatom samplem17716115.9
    Zinc痢/l109273026.2