Lakes and Watercourses

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The concentration of base cations in limed lakes must be determined on the basis of reliable readings taken prior to liming or by calculating the calcium concentration from the magnesium content of the water and the Ca/Mg ratio in nearby, similar but unlimed waters. The latter alternative presupposes that limestone containing no magnesium (ie, limestone containing little dolomite) has been used for liming. If present alkalinity is less than 0.01 meq/l, the alkalinity ratio derived above cannot be used as a basis for classifying deviation. Instead, a modified alkalinity ratio can be estimated as shown below. alk < –0.01 –0.01< alk < 0.01 alk ≥ 0.01 alk o > 0.01 0.25 (–0.01 /alk) (0.01/alk o ) (0.01/alk o ) 2 –100 (0.01 – alk) alk/alk o –0,01< alk o < 0.01 (–0.01 /alk) 2 –100 (alk o + 0.01) 2 –100 (alk o – alk) alk o < –0.01 alk o /alk The modified alkalinity ratio can be used instead of the normal alkalinity ratio to determine the deviation class in the deviation table. Example: Present alkalinity is measured (by acidity analysis) at -0.02 meq/l. Pre-industrial alkalinity is estimated at 0.02 meq/l. The modified alkalinity ratio (using the expression at top left above) will then be 0.25 (- 0.01/-0.02)(0.01/0.02) = 0.25 · 0.5 · 0.5 = 0.06. It may be seen from the deviation table that this represents deviation class 5. 0.40 Non-marine sulphate concentration (meq/l) 0.35 0.30 0.25 0.20 0.15 0.10 Extremely severe acidification Very severe acidification Severe Moderate acidification acidification Figure 2. Diagram showing deviation class (acidification) based on recorded alkalinity and concentration of nonmarine sulphate. 0.05 Insignificant acidification 0 –0.20 –0.15 –0.10 –0.05 0 0.05 0.10 0.15 0.20 Alkalinity (meq/l) 39
The pre-industrial concentration of sulphate (SO 4 * o ) in the majority of acidified waters or waters sensitive to acidification can safely be set at zero, in which case the alkalinity ratio and deviation classification will depend solely on present alkalinity and sulphate concentration. This means that the deviation class (acidification class) can be identified directly from Figure 2. Comments Classifications must be based on samples taken and analyses made in accordance with the Swedish EPA Environmental Monitoring Handbook. The assessments should be based on data from at least 12 samples taken either monthly over one year, every other month over two years or quarterly over three years (see Environmental Monitoring Handbook – water chemistry of lakes and water chemistry of watercourses). The calculations and classifications described above are intended to refer to the median values of the relevant parameters during the sampling period. If assessments are made on the basis of single samples, such as synoptic studies, this should be stated. If so, samples must have been taken at a time of year when the acidity of the water is reasonably stable. The class boundaries given for assessing current conditions take account of the fact that lakes and running waters can be appreciably more acidic for a short time during the spring flood than during the rest of the year. However, ”acidic surges” during the spring flood may cause pronounced biological effects in waters (principally streams), even though buffering capacity is fairly or even very good at other times of year. In such cases, relevant assessments of the acidity of such watercourses require study of both biological parameters and water chemistry. References Bernes, C. (1991): Acidification and liming of Swedish lakes and watercourses. Monitor 12, Swedish EPA. Wilander, A. (1998): Surhet/försurning (”Acidity/acidification”). – From: T. Wiederholm (Ed.). Bedömningsgrunder för miljökvalitet – Sjöar och vattendrag. Bakgrundsrapport 1 – Kemiska och fysikaliska parametrar (”Environmental Quality Criteria – Lakes and Watercourses. Background report 1 – Chemical and physical parameters”). Swedish EPA Report 4920. In Swedish with English summary. 40
Page 1 and 2: Environmental Quality Criteria - La
Page 3 and 4: TO ORDER Swedish Environmental Prot
Page 5 and 6: Reference Group Mats Bengtsson, Swe
Page 7 and 8: Summary This report on lakes and wa
Page 11 and 12: included. In addition to a large nu
Page 13 and 14: ased estimates are used. Given that
Page 15 and 16: TABLE 1. SUMMARY of parameters incl
Page 17 and 18: 16 The current conditions scale in
Page 19 and 20: (in Swedish with English summary).
Page 21 and 22: conditions for watercourse flora an
Page 23 and 24: show the availability of nitrogen i
Page 25 and 26: Mean concentration of total phospho
Page 27 and 28: TABLE 9. DEVIATION from reference v
Page 29 and 30: Comments Classifications must be ba
Page 31 and 32: winter/spring, i.e. ice-covered per
Page 33 and 34: Light conditions Introduction Light
Page 35 and 36: TABLE 13. CURRENT CONDITIONS: turbi
Page 37 and 38: Acidity / acidification Introductio
Page 39: industrial pH). The change in acidi
Page 43 and 44: very high degree of reliability and
Page 45 and 46: TABLE 19. CURRENT CONDITIONS: metal
Page 47 and 48: TABLE 22. DEVIATION from reference
Page 49 and 50: TABLE 24. (continued) Cu Zn Cd Pb C
Page 51 and 52: Swedish EPA (1993): Metals and the
Page 53 and 54: Assessment of current conditions TA
Page 55 and 56: TABLE 29. CURRENT CONDITIONS: poten
Page 59 and 60: References Cronberg, G., Lindmark,
Page 61 and 62: (see Appendix 1). If submerged and
Page 63 and 64: References Andersson, B. (1998): Va
Page 65 and 66: The genera in question and their tr
Page 67 and 68: Benthic fauna Introduction Benthic
Page 69 and 70: TABLE 41. CURRENT CONDITIONS: botto
Page 71 and 72: Comments The assessment must be bas
Page 73 and 74: has yielded better results than did
Page 75 and 76: TABLE 45. CURRENT CONDITIONS: fish,
Page 81 and 82: TABLE 48. (Contd.) Proportion of al
Page 84 and 85: Presentation of data When using the
Page 86 and 87: APPENDIX 1 Ceratophyllum demersum 1
Page 88 and 89: APPENDIX 2 Calculation of index and
Page 90 and 91:
APPENDIX 2 Table 1b. Indicator gene
Page 92 and 93:
Genus Indicator value -------------
Page 94 and 95:
APPENDIX 2 45 Planorbis sp. 46 Anis
Page 96 and 97:
APPENDIX 2 214 Leuctra hippopus 215
Page 98 and 99:
APPENDIX 2 384 Tinodes waeneri 385
Page 100 and 101:
APPENDIX 2 (6) O/C index (Wiederhol
Page 102 and 103:
APPENDIX 3 Dace Stäm Leuciscus leu
Page 106:
REPORT 5050 Environmental Quality C
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