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- Title
Trends in sulfate, base cations and H+ concentrations in bulk precipitation and throughfall at integrated monitoring sites in Finland 1989-1995
- Authors
Ukonmaanaho, L.; Starr, M.; Ruoho-Airola, T.
- Abstract
Temporal trends in sulfate, base cation (Ca2+ + Mg2+ + K+), and H+ ion concentrations in bulk precipitation and throughfall samples collected over a seven year period (1989-95) in four forested catchments in Finland are presented. The catchments are in remote locations and span the boreal zone (61-69 degrees N). The stands represent old, undisturbed forests, and are composed of varying proportions of Scots pine, Norway spruce and deciduous species (mainly Betula spp.). Monthly SO42--S and H+ ion concentrations in bulk precipitation averaged overthe study period and catchments were: 18.7 mu mol L-1 and 32.3 mu mol L-1. The corresponding values for throughfall were: 37.4 mu mol L-1and 32.4 mu mol L-1. Sulfate and H+ ion concentrations in bulk precipitation and throughfall both showed negative linear trends, which were significant (p < 0.05) for the three southernmost catchments. Concentrations and trend slope decreased northwards (e.g., bulk precipitation SO42--S slope estimates: -1.6 to -1.0 mu mol L-1 yr-1). The decline was greater for throughfall than for bulk precipitation, indicating a proportionally greater reduction in dry deposition than wet. The sum of base cation concentrations averaged 12.1 mu mol((+)) L-1 in bulk precipitation and 83.1 mu mol((+)) L-1 in throughfall.There were no significant trends in the sum of base cations (p > 0.05). It is concluded that the reported reduction in S emissions over the study period has resulted in a significant reduction in the acidity and SO42- concentration of bulk precipitation, and this reduction has has been reflected in throughfall concentrations. The greatest reduction has taken place in the southern part of the country.
- Subjects
FINLAND; BIOGEOCHEMISTRY; ATMOSPHERIC deposition; ACID precipitation (Meteorology)
- Publication
Water, Air & Soil Pollution, 1998, Vol 105, Issue 1-2, p353
- ISSN
0049-6979
- Publication type
Article
- DOI
10.1023/A:1005087627364