Browsing by Subject "hapan laskeuma"

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  • Forsius, Martin (National Board of Waters and the Environment. Vesi- ja ympäristöhallitus, 1992)
    Publications of the Water and Environment Research Institute 10
    Yhteenveto: Järvien happamoituminen Suomessa: Alueellinen vedenlaatu ja kriittinen kuormitus
  • Kenttämies, Kaarle (Vesihallitus, 1979)
    Vesientutkimuslaitoksen julkaisuja 30, 42-45
    Tiivistelmä: Ilman rikkilaskeuma ja järvien happamoituminen Suomessa.
  • Soveri, Jouko (National Board of Waters and the Environment, Vesi- ja ympäristöhallitus, 1991)
    Publications of the Water and Environment Research Institute 8, 29-48
  • Nygren, Pekka; Hari, Pertti (Suomen metsätieteellinen seura, 1992)
  • Soveri, Jouko (National Board of Waters and the Environment, Vesi- ja ympäristöhallitus, 1991)
    Publications of the Water and Environment Research Institute 8, 3-28
  • Johansson, Matti (Finnish Environment Institute, 1999)
    Monographs of the Boreal Environment Research 13
  • Bergström, Irina; Mäkelä, Katariina; Starr, Michael (Ministry of the Environment, 1995)
    Ministry of the Environment, Environmental Policy Department; Report 1/1995
  • Vanhala, Pekka (Finnish Environment Institute, 1999)
    Monographs of the Boreal Environment Research 14
  • Raunemaa, T.; Hautojärvi, A.; Katainen, H.-S.; Erkinjuntti, R.; Gerlander, M.; Kaisla, K. (Suomen metsätieteellinen seura, 1981)
  • Vuorenmaa, Jussi (Finnish Environment Institute, 2007)
    Monographs of the Boreal Environment Research 30
    The present work provides a regional-scale assessment of the changes in acidifying deposition in Finland over the past 30 years and the current pattern in the recovery of acid-sensitive lakes from acidification in relation to changes in sulphate deposition. This information is needed for documenting the ecosystem benefits of costly emission reduction policies and further actions in air pollution policy. The development of sulphate deposition in Finland reflects that of European SO2 emissions. Before the 1990s, reductions in sulphur emissions in Europe had been relatively small and sulphate deposition showed no consistent trends. Due to emission reduction measures that were then taken, sulphate deposition started to clearly decline from the late 1980s. The bulk deposition of sulphate has declined 40-60% in most parts of the country during 1990-2003. The decline in sulphate deposition exceeded the decline of base cation deposition, which resulted in a decrease in acidity and acidifying potential of deposition over the 1990s. Nitrogen deposition also decreased since the late 1980s, but less than that of sulphate, and levelling off during the 1990s. Sulphate concentrations in all types of lakes throughout Finland have declined from the early 1990s. The relative decrease in lake sulphate concentrations (average 40-50%) during 1990-2003 was rather similar to the decline in sulphate deposition, indicating a direct response to the reduction in deposition. There are presently no indications of elevated nitrate concentrations in forested headwater lakes. Base cation concentrations are still declining in many lakes, especially in south Finland, but to a lesser extent than sulphate allowing buffering capacity (alkalinity) to increase. The recovery has been strongest in lakes in which sulphate has been the major acidifying agent, and recovery has been the strongest and most consistent in lakes in south Finland. The recovery of lakes in central Finland and north Finland is not as widespread and strong as observed in south. Many catchments, particularly in central Finland, have a high proportion of peatlands and therefore high TOC concentrations, and runoff-induced surges of organic acids have been an important confounding factor suppressing the recovery of pH and alkalinity in these lakes. Chemical recovery is progressing even in the most acidified lakes, but the buffering capacity of many lakes is still low and still sensitive to acidic input. Chemical recovery is resulting in biological recovery with populations of acid-sensitive fish species increasing. Increasing TOC concentrations are indicated in small forest lakes in Finland, which appear to be related to decreasing sulphate deposition and improved acid-base status of the soil. A new challenge is climate change with potential trends in temperature, precipitation and runoff, which are expected to affect future chemical and biological recovery from acidification. The potential impact of mobilization and leaching of organic acids may become particularly important in Finnish conditions. Long-term environmental monitoring has evidently shown the success of international emission abatement strategies. The importance and value of integrated monitoring approach including physical, chemical and biological variables is clearly indicated, and continuous environmental monitoring is needed as a scientific basis for further actions in air pollution policy. The effect of climate change will increase data requirements, and should be taken into account when assessing long-term surface water quality and developing future monitoring networks, due to more complex processes involved.
  • Mannio, Jaakko (Finnish Environment Institute, 2001)
    Monographs of the Boreal Environment Research 18
    The present work provides a national scale assessment of the trace metal contamination of small headwater lakes and the recent development of acidified lakes in Finland. The information is needed as a scientific basis for further actions in air pollution policy. The study is based on observations in a national monitoring network of lake acidification.Anthropogenic, atmospheric deposition is primarily responsible for the increase of Cd, Hg, Pb and As in headwater lake sediments. However, a decline of 20 to 40% of the accumulation of these elements within the last decades was observed, indicating a relatively fast response to the decline in the atmospheric deposition, and that the accumulated stores of atmospheric trace metals in the catchment soils are not dominating the supply of trace elements to lakes.Lake waters reflected atmospheric trace metal pollution as well, but it was not as clearly quantifiable. Acidity controls in particular the level of Cd and Zn, while organic matter (humus) controls more the level of Cr, Fe, Cu and Ni in headwater lakes. Lead, Mn and Al concentrations are affected by both these factors. Humus acts as a carrier for trace metals from catchments soils to surface waters, irrespectively of their original source.Based on comparable chemical data sets, the risks of biological effects in lakes due to trace metals are lower in Finland than in Sweden and Norway. Trace metal levels in lake waters are less critical for the biota than acidity and inorganic (labile) aluminium levels.Due to acidification, there where estimated to be 2200-4400 damaged fish populations in southern and central Finland. Most of these populations are roach in lakes smaller than ten hectares. Sulphate concentrations have declined in all types of small lakes throughout Finland in the 1990s, indicating a clear response to the sulphur emission reductions. Base cation concentrations are still declining in lakes especially in southern Finland, but to a lesser extent than sulphate.There are presently no indications of elevated nitrate levels in forested headwater lakes. The increase in buffer capacity (chemical recovery) was relatively uniform throughout the country, except that the changes were not as significant statistically and by magnitude in the dilute lakes in northern Finland.Nearly 5000 headwater lakes larger than four hectares were estimated to be recovering from acidification at present. The chemical conditions were found to be improving throughout Finland, and first perch population recoveries in southern Finland were observed.The monitoring and survey results presented here are an example of an approach, where both spatial and temporal data from several sources are aggregated. This facilitates the estimation of regional changes and quantifies the changes on national scale. The consistent monitoring provides also sound basis for further modelling of recovery processes and scenario assessment.A new challenge is the interaction of acidification/recovery processes and trace metals with possible trends in temperature and hydrology due to global climate change. This should be taken into account when assessing long-term surface water quality and developing future monitoring networks. Empirical data in space and time is needed to judge, whether the emission reduction measures have been efficient.