Deposition of base-cations in Europe and its role in acid neutralization and forest nutrition
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Series / Report no.
Open Access
Type
Report
Language
en
Date
1996-06-30
Research Projects
Organizational Units
Journal Issue
Title
Deposition of base-cations in Europe and its role in
acid neutralization and forest nutrition
Translated Title
Depositie van basische kationen in Europa en de
bijdrage daarvan aan zuurneutralisatie en
bosnutritie
Published in
Abstract
In relatie tot de verzuringsproblematiek wordt meestal
weinig aandacht besteed aan de rol van basische kationen zoals Na+, Mg2+,
Ca2+ en K+. Echter, door depositie van basische kationen kan een deel van
de zure depositie geneutraliseerd worden. Daarnaast zijn basische kationen
belangrijke nutrienten voor ecosystemen. Tot op heden zijn op Europese
schaal geen betrouwbare depositieschattingen voor basische kationen
aanwezig, alhoewel deze informatie nodig is voor het bepalen van kritische
depositiewaarden en haar overschrijdingen. In dit rapport worden kaarten
van de totale (natte en droge) depositie in Europa gepresenteerd welke zijn
gebaseerd op de zogenaamde 'inferentie' modellering. De natte depositie is
gekarteerd op basis van resultaten van veldmetingen op meer dan 600 lokaties
verspreid over Europa. De berekende depositievelden weerspiegelen de
geografische variatie in bronnen, landgebruik en klimaat. Vergelijking met
berekende potentieel zure deposities laat zien dat in Zuid-Europa over het
algemeen meer dan 50% van de potentieel zure depositie geneutraliseerd wordt
door depositie van basische kationen. In Centraal- en Noordwest-Europa is
dit in de regel minder dan 25%. De laagste depositie van basische kationen
in verhouding tot de depositie van potentieel zuur vindt plaats in
Zuid-Scandinavie, Denemarken, Noord-Duitsland en Nederland. Voor de
neutralisatie van zuurvormende anionen in neerslag werd een vergelijkbaar
ruimtelijk patroon gevonden. De gemodelleerde deposities komen goed overeen
met depositieschattingen die op 174 locaties verspreid over Europa gemaakt
zijn op basis van doorval- en neerslagmetingen, zeker gezien de relatief
grote onzekerheid in beide schattingen. Gemiddeld waren de schattingen niet
significant verschillend. Wel bleek het model de droge depositie op bossen
nabij lokale bronnen systematisch te onderschatten. Met behulp van
foutenvoortplantings-technieken is voor een gemiddelde gridcel van 10x20 km
in Europa de toevallige en systematische fout in de totale depositie van
basische kationen geschat op 35-50%, respectievelijk
25-40%.
In considering acidification problems, emphasis is seldom placed on the role of deposition of base-cations such as Na+, Mg2+, Ca2+ and K+. Besides their ability to neutralize acid input, base-cations are found to be important nutrient elements for ecosystems. Up to now no accurate estimates of base-cation deposition are available on a European scale, despite their indispensability for the estimation of critical loads as well as exceedances. In this report, maps of total (i.e. wet and dry) base-cation deposition in Europe, based on the so-called inferential modeling technique are presented. Wet deposition is mapped on the basis of field measurements made at approximately 600 sites scattered over Europe. Generally, deposition fields found resemble the geographic variability of sources, land use and climate. In large parts of southern Europe more than 50% of the potential acid deposition is found to be counteracted by deposition of the sum of non-sea salt Mg2+, Ca2+ and K+. In central and northwestern Europe base-cation deposition usually amounts to less than 25% of the acid input. The lowest base-cation deposition relative to potential acid deposition is found in southern Scandinavia, Denmark, northern Germany and the Netherlands. A similar spatial pattern is found for the neutralization of acid anions in precipitation. Modeled deposition estimates compare reasonably well with deposition estimates derived from throughfall and bulk-precipitation measurements made at 174 sites scattered over Europe, taking into account the relatively large uncertainty in both estimates. On average, no significant differences are found, but the model seems to underestimate dry deposition of base-cations near local sources. Using error propagation, the random and systematic errors in total deposition for an average grid cell of 10x20 km were estimated to equal 35-50% and 25-40%, respectively.
In considering acidification problems, emphasis is seldom placed on the role of deposition of base-cations such as Na+, Mg2+, Ca2+ and K+. Besides their ability to neutralize acid input, base-cations are found to be important nutrient elements for ecosystems. Up to now no accurate estimates of base-cation deposition are available on a European scale, despite their indispensability for the estimation of critical loads as well as exceedances. In this report, maps of total (i.e. wet and dry) base-cation deposition in Europe, based on the so-called inferential modeling technique are presented. Wet deposition is mapped on the basis of field measurements made at approximately 600 sites scattered over Europe. Generally, deposition fields found resemble the geographic variability of sources, land use and climate. In large parts of southern Europe more than 50% of the potential acid deposition is found to be counteracted by deposition of the sum of non-sea salt Mg2+, Ca2+ and K+. In central and northwestern Europe base-cation deposition usually amounts to less than 25% of the acid input. The lowest base-cation deposition relative to potential acid deposition is found in southern Scandinavia, Denmark, northern Germany and the Netherlands. A similar spatial pattern is found for the neutralization of acid anions in precipitation. Modeled deposition estimates compare reasonably well with deposition estimates derived from throughfall and bulk-precipitation measurements made at 174 sites scattered over Europe, taking into account the relatively large uncertainty in both estimates. On average, no significant differences are found, but the model seems to underestimate dry deposition of base-cations near local sources. Using error propagation, the random and systematic errors in total deposition for an average grid cell of 10x20 km were estimated to equal 35-50% and 25-40%, respectively.
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