Lakes and Watercourses
Lakes and Watercourses
Lakes and Watercourses
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Comments<br />
Classifications must be based on samples taken <strong>and</strong> analyses made in<br />
accordance with the Swedish EPA Environmental Monitoring H<strong>and</strong>book.<br />
The scales should be used bearing in mind the wide natural<br />
variation between individual lakes <strong>and</strong> watercourses <strong>and</strong> from year to<br />
year. The number of sampling occasions or the time scale on which the<br />
various assessments are based represents minimum figures. If <strong>and</strong> when<br />
assessments are made on the basis of more limited data, this should be<br />
stated.<br />
The scale for N/P ratios in lakes is intended to be used provisionally<br />
<strong>and</strong> with a degree of feedback as to results obtained. The ratios have been<br />
obtained using older analytical methods for total nitrogen (Kjeldahl-N +<br />
ammonium-N) <strong>and</strong> are affected in calculation terms by the reduction in<br />
the concentrations of total nitrogen obtained using new analytical<br />
methods (total-N using Swedish St<strong>and</strong>ard SSO28131). No correction has<br />
been made to take account of this, however. The effects the class<br />
boundaries are intended to identify may therefore occur at somewhat<br />
lower ratios than those given in the criteria.<br />
References<br />
Alabaster, J.S. & Lloyd, R. (1982): Water quality criteria for freshwater fish. 2nd<br />
ed. – Butterworths, London.<br />
Swedish Environmental Protection Agency (1991): Bedömningsgrunder för sjöar<br />
och vattendrag (”Quality criteria for lakes <strong>and</strong> watercourses”). Swedish EPA<br />
General Guidelines 90:4.<br />
Persson, G. Växtnäringsämnen/eutrofiering (”Nutrients/eutrophication”). – From:<br />
T. Wiederholm (Ed.). Bedömningsgrunder för miljökvalitet - Sjöar och vattendrag.<br />
Bakgrundsrapport 1 – Kemiska och fysikaliska parametrar (”Environmental Quality<br />
Criteria – <strong>Lakes</strong> <strong>and</strong> <strong>Watercourses</strong>. Background report 1 – Chemical <strong>and</strong> physical<br />
parameters”). Swedish EPA Report 4920.<br />
Premazzi, G. & Chiaudani, G. (1992): Ecological quality of surface waters.<br />
Quality assessment for European Community lakes. – ECSC-EEC-EAEC,<br />
Brussels, Luxembourg.<br />
Wiederholm, T., Welch, E., Persson, G., Karlgren, L. & von Brömssen, U. (1983):<br />
Bedömningsgrunder och riktvärden för fosfor i sjöar och vattendrag. Underlag för<br />
försöksverksamhet. (”Quality criteria <strong>and</strong> guide values for phosphorus in lakes <strong>and</strong><br />
watercourses. Background data for experiments”) – Swedish EPA PM 1705.<br />
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