A. Barkman et M. Alveteg, Identifying potentials for reducing uncertainty in critical load calculations using the PROFILE model, WATER A S P, 125(1-4), 2001, pp. 33-54
A sensitivity analysis was performed testing weathering rates, critical loa
ds and exceedances for Swedish forest soils using Monte Carlo simulations o
f the PROFILE model. Different subsets of input data were investigated with
respect to their potential to reduce data uncertainty at site level but al
so for modified estimates of the 5%-ile critical load and the 95%-ile excee
dance on 150x150 km resolution. Physical soil properties were of dominant i
mportance for all sites and yield up to 62% reduction of the output standar
d deviation in weathering rate. The study showed that the critical ratio of
base cations to inorganic aluminium (Bc/Al ratio) in the soil solution was
of major importance for reducing data uncertainty in critical loads and ex
ceedance estimates. The critical Bc/Al ratio was found to be important for
reducing data uncertainties in modified estimates of the 5%-ile critical lo
ad and the 95%-ile exceedance, in particular in the northern part of Sweden
. Atmospheric deposition, uptake and litterfall were more important for red
ucing data uncertainty in the southern part. Physical soil properties and e
specially mineral content were found to be less important for reducing data
uncertainties in critical loads and exceedance estimates. The greatest sco
pe for reducing data uncertainties in an applied perspective is to improve
estimates of atmospheric deposition of anions and cations as well as uptake
and litterfall of base cations and nitrogen.