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Surface water acidification and critical loads

exploring the F-factor

Rapp, Lars and Bishop, Kevin (2009). Surface water acidification and critical loads. Hydrology and earth system sciences. 13 :11 , 2191-2201
[Research article]

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As acid deposition decreases, uncertainties in methods for calculating critical loads become more important when judgements have to be made about whether or not further emission reductions are needed. An important aspect of one type of model that has been used to calculate surface water critical loads is the empirical F-factor which estimates the degree to which acid deposition is neutralised before it reaches a lake at any particular point in time relative to the pre-industrial, steady-state water chemistry conditions. In this paper we will examine how well the empirical F-functions are able to estimate pre-industrial lake chemistry as lake chemistry changes during different phases of acidification and recovery. To accomplish this, we use the dynamic, process-oriented biogeochemical model SAFE to generate a plausible time series of annual runoff chemistry for ca 140 Swedish catchments between 1800 and 2100. These annual hydrochemistry data are then used to generate empirical F-factors that are compared to the “actual” F-factor seen in the SAFE data for each lake and year in the time series. The dynamics of the F-factor as catchments acidify, and then recover are not widely recognised. Our results suggest that the F-factor approach worked best during the acidification phase when soil processes buffer incoming acidity. However, the empirical functions for estimating F from contemporary lake chemistry are not well suited to the recovery phase when the F-factor turns negative due to recovery processes in the soil. This happens when acid deposition has depleted the soil store of BC, and then acid deposition declines, reducing the leaching of base cations to levels below those in the pre-industrial era. An estimate of critical load from water chemistry during recovery and empirical F functions would therefore result in too low critical loads that are too low. Therefore, the empirical estimates of the F-factor are a significant source of uncertainty in the estimate of surface water critical loads and related calculations for quantifying lake acidification status, especially now that acid deposition has declined across large areas of Europe and North America

Authors/Creators:Rapp, Lars and Bishop, Kevin
Title:Surface water acidification and critical loads
Subtitle:exploring the F-factor
Series Name/Journal:Hydrology and earth system sciences
Year of publishing :2009
Page range:2191-2201
Number of Pages:11
Publisher:Copernicus Publications
Associated Programs and Other Stakeholders:SLU - Environmental assessment > Programme Acidification
SLU - Environmental assessment > Programme Lakes and watercourses
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 3.0
Full Text Status:Public
Agris subject categories.:M Aquatic sciences and fisheries > M01 Fisheries and aquaculture - General aspects
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Fish and Aquacultural Science
Agrovoc terms:acidification, methods
Keywords:surface water, acidification, f-factor
Permanent URL:
Additional ID:
Type of IDID
Web of Science (WoS)000272232400013
ID Code:12062
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By: SLUpub Connector
Deposited On:10 Apr 2015 08:33
Metadata Last Modified:09 Sep 2020 14:17

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