title: Regional scale evidence for improvements in surface water chemistry 1990-2001.
abstract: The main aim of the international UNECE monitoring program ICP Waters under the Convention of Long-range Transboundary Air Pollution (CLRTAP) is to assess, on a regional basis, the degree and geographical extent of the impact of atmospheric pollution, in particular acidification, on surface waters. Regional trends are calculated for 12 geographical regions in Europe and North America, comprising 189 surface waters sites. From 1990-2001 sulphate concentrations decreased in all but one of the investigated regions. Nitrate increased in only one region, and decreased in three North American regions. Improvements in alkalinity and pH are widely observed. Results from the ICP Waters programme clearly show widespread improvement in surface water acid-base chemistry, in response to emissions controls programs and decreasing acidic deposition. Limited site-specific biological data suggest that continued improvement in the chemical status of acid-sensitive lakes and streams will lead to biological recovery in the future.
authors.affiliation: Norwegian Institute for Water Research, P.O. Box 173, Kjelsås, N-0411 Oslo, Norway. brit.skjelkvaale@niva.no
authors.forename: B L
authors.initials: BL
authors.lastname: Skjelkvåle
authors.forename: J L
authors.initials: JL
authors.lastname: Stoddard
authors.forename: D S
authors.initials: DS
authors.lastname: Jeffries
authors.forename: K
authors.initials: K
authors.lastname: Tørseth
authors.forename: T
authors.initials: T
authors.lastname: Høgåsen
authors.forename: J
authors.initials: J
authors.lastname: Bowman
authors.forename: J
authors.initials: J
authors.lastname: Mannio
authors.forename: D T
authors.initials: DT
authors.lastname: Monteith
authors.forename: R
authors.initials: R
authors.lastname: Mosello
authors.forename: M
authors.initials: M
authors.lastname: Rogora
authors.forename: D
authors.initials: D
authors.lastname: Rzychon
authors.forename: J
authors.initials: J
authors.lastname: Vesely
authors.forename: J
authors.initials: J
authors.lastname: Wieting
authors.forename: A
authors.initials: A
authors.lastname: Wilander
authors.forename: A
authors.initials: A
authors.lastname: Worsztynowicz
mesh_terms: D015258:Acid Rain; D004784:Environmental Monitoring / Q000379:methods*; D004787:Environmental Pollution; D005060:Europe; D005618:Fresh Water; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007391:International Cooperation; D009566:Nitrates / Q000032:analysis; D009656:North America; D013431:Sulfates / Q000032:analysis; D013997:Time Factors; D014480:United Nations; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D015258:Acid Rain; D009566:Nitrates; D013431:Sulfates; D014874:Water Pollutants, Chemical