Water, Air, and Soil Pollution

, Volume 85, Issue 2, pp 577–582 | Cite as

Trends in surface water acidification at ecological monitoring sites in southeastern Canada (1981–1993)

  • D. S. Jeffries
  • T. A. Clair
  • P. J. Dillon
  • M. Papineau
  • M. P. Stainton
Part III Long Term Trends in Acidification


Atmospheric deposition and surface water chemistry have been monitored intensively at 5 geologically “sensitive” sites in southeastern Canada. The sites receive differing acid inputs that span the entire range found in Canada. Surface water data collected at 9 stations from 1981 to 1993 for SO 4 2− , NO 3 , Alkalinity, DOC, pH, Ca2+ and Mg2+ have been analyzed to detect monotonic trends. Similarities between the temporal patterns and trends for SO 4 2− in deposition and surface water suggest that they are strongly linked at our sites. Our 13-year datasets showed significant negative SO 4 2− trends at the 3 Ontario sites and a positive trend in Nova Scotia. A climatically-induced SO 4 2− increase in northwestern Ontario has been reversed. Mobilization and export of adsorbed SO 4 2− and/or reoxidized S from the basins of central Ontario sites is delaying their recovery. Two of our 9 stations (in Quebec and central Ontario) are continuing to acidify. The 2 Nova Scotia stations have the highest DOC levels and both exhibit a decreasing trend. Ionic compensation for declining SO 4 2− varies from station to station, sometimes involving an Alk increase, sometimes a base cation decrease, and sometimes more complex combinations. Additional factors (e.g. climatic variation) also influence variable trends, and data records longer than those presently available will be needed to unequivocally verify acidification recovery.

Key words

acidification water chemistry statistical trends monitoring recovery 


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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • D. S. Jeffries
    • 1
  • T. A. Clair
    • 2
  • P. J. Dillon
    • 3
  • M. Papineau
    • 4
  • M. P. Stainton
    • 5
  1. 1.National Water Research InstituteBurlingtonCanada
  2. 2.Environment Canada, Atlantic RegionSackvilleCanada
  3. 3.Ontario Ministry of Environment and EnergyDorsetCanada
  4. 4.Centre St. LaurentSte-FoyCanada
  5. 5.Freshwater InstituteWinnipegCanada

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