Calculating critical loads of acid deposition with PROFILE ? A steady-state soil chemistry model

1992 ◽  
Vol 63 (1-2) ◽  
pp. 119-143 ◽  
Author(s):  
Per Warfvinge ◽  
Harald Sverdrup
Keyword(s):  
Steady State ◽  
Acid Deposition ◽  
Critical Loads ◽  
Soil Chemistry

scholarly journals Critical Loads of Acid Deposition for Wilderness Lakes in the Sierra Nevada (California) Estimated by the Steady-State Water Chemistry Model

2013 ◽  
Vol 225 (1) ◽  
Author(s):  
Glenn D. Shaw ◽  
Ricardo Cisneros ◽  
Donald Schweizer ◽  
James O. Sickman ◽  
Mark E. Fenn
Keyword(s):  
Steady State ◽  
Water Chemistry ◽  
Sierra Nevada ◽  
Acid Deposition ◽  
Critical Loads ◽  
State Water

scholarly journals The development of an approach to assess critical loads of acidity for woodland habitats in Great Britain

2004 ◽  
Vol 8 (3) ◽  
pp. 355-365 ◽  
Author(s):  
S. J. Langan ◽  
J. Hall ◽  
B. Reynolds ◽  
M. Broadmeadow ◽  
M. Hornung ◽  
...  
Keyword(s):  
Air Pollution ◽  
Steady State ◽  
Critical Load ◽  
Acid Deposition ◽  
Critical Loads ◽  
Balance Model ◽  
Mass Balance Model ◽  
Simple Mass ◽  
The Uk ◽  
Simple Mass Balance Model

Abstract. Alongside other countries that are signatories to the UNECE Convention Long Range Transboundary on Air Pollution, the UK is committed to reducing the impact of air pollution on the environment. To advise and guide this policy in relation to atmospheric emissions of sulphur and nitrogen, a critical load approach has been developed. To assess the potential impact of these pollutants on woodland habitats a steady state, simple mass balance model has been parameterised. For mineral soils, a Ca:Al ratio in soil solution has been used as the critical load indicator for potential damage. For peat and organic soils critical loads have been set according to a pH criterion. Together these approaches have been used with national datasets to examine the potential scale of acidification in woodland habitats across the UK. The results can be mapped to show the spatial variability in critical loads of the three principal woodland habitat types (managed coniferous, managed broadleaved/ mixed woodland and unmanaged woodland). The results suggest that there is a wide range of critical loads. The most sensitive (lowest) critical loads are associated with managed coniferous followed by unmanaged woodland on peat soils. Calculations indicate that at steady state, acid deposition inputs reported for 1995–1997 result in a large proportion of all the woodland habitats identified receiving deposition loads in excess of their critical load; i.e. critical loads are exceeded. These are discussed in relation to future modelled depositions for 2010. Whilst significant widespread negative impacts of such deposition on UK woodland habitats have not been reported, the work serves to illustrate that if acid deposition inputs were maintained and projected emissions reductions not achieved, the long-term sustainability of large areas of woodland in the UK could be compromised. Keywords: critical loads, acid deposition, acidification, woodland, simple mass balance model, sustainability

scholarly journals Critical loads of sulphur and nitrogen for freshwaters in Great Britain and assessment of deposition reduction requirements with the First-order Acidity Balance (FAB) model

2000 ◽  
Vol 4 (1) ◽  
pp. 125-140 ◽  
Author(s):  
C. Curtis ◽  
T. Allott ◽  
J. Hall ◽  
R. Harriman ◽  
R. Helliwell ◽  
...  
Keyword(s):  
Great Britain ◽  
Water Chemistry ◽  
Critical Load ◽  
Acid Deposition ◽  
Critical Loads ◽  
Freshwater Ecosystems ◽  
Acid Neutralizing Capacity ◽  
First Order ◽  
Fab Model ◽  
S Deposition

Abstract. The critical loads approach is widely used within Europe to assess the impacts of acid deposition on terrestrial and freshwater ecosystems. Recent work in Great Britain has focused on the national application of the First-order Acidity Balance (FAB) model to a freshwaters dataset of 1470 lake and stream water chemistry samples from sites across Britain which were selected to represent the most sensitive water bodies in their corresponding 10 km grid square. A ``Critical Load Function" generated for each site is compared with the deposition load of S and N at the time of water chemistry sampling. The model predicts that when catchment processes reach steady-state with these deposition levels, increases in nitrate leaching will depress acid neutralizing capacity (ANC) below the critical threshold of 0 μeql-1 at more than a quarter of the sites sampled, i.e. the critical load of acid deposition is exceeded at these sites. The critical load exceedances are generally found in upland regions of high deposition where acidification has been previously recognised, but critical loads in large areas of western Scotland are also exceeded where little biological evidence of acidification has yet been found. There is a regional variation in the deposition reduction requirements for protection of the sampled sites. The FAB model indicates that in Scotland, most of the sampled sites could be protected by sufficiently large reductions in S deposition alone. In the English and Welsh uplands, both S and N deposition must be reduced to protect the sites. Current international commitments to reduce S deposition throughout Europe will therefore be insufficient to protect the most sensitive freshwaters in England and Wales. Keywords: critical loads; acidification; nitrate; FAB model; acid deposition

scholarly journals Modelling long-term changes in stream water and soil chemistry in catchments with contrasting vulnerability to acidification (Lysina and Pluhuv Bor, Czech Republic)

2003 ◽  
Vol 7 (4) ◽  
pp. 525-539 ◽  
Author(s):  
J. Hruška ◽  
P. Krám
Keyword(s):  
Czech Republic ◽  
Critical Loads ◽  
Soil Chemistry ◽  
Stream Water ◽  
Base Saturation ◽  
Soil Base ◽  
Magic Model ◽  
Water Ph ◽  
Annual Discharge ◽  
Gothenburg Protocol

Abstract. In two Czech catchments covered by Norway spruce forests, the MAGIC model was used to simulate annual stream water and soil chemistry for the period 1851–2030. These two sites represent geochemical end-members of ecosystem sensitivity to acidification (acid-sensitive granitic Lysina catchment vs. acid-resistant serpentinitic Pluhuv Bor catchment). Although the total deposition of sulphur to the catchments declined by 75% between 1990 and 2002, the recovery of stream water pH was relatively small over this period. At Lysina, the annual discharge-weighted mean pH of stream water increased only from 3.92 to 4.01, although SO4 concentration declined very sharply from 570 μeq L–1 in 1990 to 150 μeq L–1 in 2002. Stream water buffering was caused mainly by dissociation of organic acids. At Pluhuv Bor, the annual mean pH varied inversely with the annual discharge. Stream water concentrations of SO4 declined dramatically at Pluhuv Bor, from 1040 μeq L–1 in 1992 to 220 μeq L–1 in 2002. Using atmospheric deposition as specified in the Gothenburg Protocol, the model predicts that, at Lysina, stream water pH will increase to 4.3 and soil base saturation will increase to 6.0% by 2030 (from 5.6% in 2002); corresponding pre-industrial stream water pH was simulated to be 5.5 and soil base saturation to be 25%. At Pluhuv Bor, the pre-industrial pH was estimated to be 7.2 and the corresponding base saturation was 94%. Large anthropogenic acidification in the 20th century caused only a small decline in pH (to 6.9) and base saturation (to 88%). Simulations in accordance with the Gothenburg Protocol predict that the pH should increase by 0.2 pH units and the base saturation by 1% by 2030. Under this protocol, critical loads of atmospheric deposition for SO4 and NO3 will not be exceeded at Pluhuv Bor but will be exceeded at Lysina. Keywords: MAGIC model, catchment, critical loads, Gothenburg Protocol, soil and water acidification, granite, serpentinite, Czech Republic

RAIN Project: Results after 8 Years of Experimentally Reduced Acid Deposition to a Whole Catchment

1993 ◽  
Vol 50 (2) ◽  
pp. 258-268 ◽  
Author(s):  
Richard F. Wright ◽  
Erik Lotse ◽  
Arne Semb
Keyword(s):  
Acid Deposition ◽  
Soil Chemistry ◽  
Nitrogen Saturation ◽  
Base Cations ◽  
Strong Acid ◽  
Catchment Scale ◽  
Exclusion Experiment ◽  
Surface Water Chemistry ◽  
Southern Norway

At Risdalsheia (southern Norway), an ongoing catchment-scale acid-exclusion experiment has been conducted since 1984 as part of the RAIN project (Reversing Acidification In Norway). Acid precipitation is collected on a 1200-m2 transparent roof, treated by ion exchange, sea salts readded, and reapplied as clean rain beneath the roof Up to 1990 annual surveys of soil chemistry have revealed no significant trends. The chemical composition of runoff has changed: sulfate decreased from about 111 μeq/L in 1984 to 38 μeq/L in 1992 and nitrate from about 33 to 5 μeq/L. Base cations decreased and alkalinity increased over the 8-yr period from −88 to −29 μeq/L to compensate for this change in strong acid anions. Much of the alkalinity change is due to the increased role of organic anions. The results fit an empirical nomograph relating alkalinity, base cations, and strong acid anions and a new empirical nomograph relating alkalinity, H+, and total organic carbon. The acid-exclusion experiment provides the first catchment-scale evidence for the reversibility of nitrogen saturation; RAIN results corroborate field observations of changes in surface water chemistry in response to reduced acid deposition as well as process-oriented, conceptual acidification models.

scholarly journals Present and potential nitrogen outputs from Norwegian soft water lakes – an assessment made by applying the steady-state First-order Acidity Balance (FAB) model

2002 ◽  
Vol 6 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Ø. Kaste ◽  
A. Henriksen ◽  
M. Posch
Keyword(s):  
Steady State ◽  
Critical Loads ◽  
N Deposition ◽  
Soft Water ◽  
N Leaching ◽  
First Order ◽  
Fab Model ◽  
The Future ◽  
N Immobilisation

Abstract. The steady-state First-order Acidity Balance (FAB) model for calculating critical loads of sulphur (S) and nitrogen (N) is applied to 609 Norwegian soft-water lakes to assess the future nitrate (NO3‾) leaching potential under present (1992-96) S and N deposition. The lakes were separated into five groups receiving increasing levels of N deposition (<25, 25-49, 50-74, 75-99 and 100-125 meq m-2yr-1). Using long-term sustainable N sink rates presently recommended for FAB model applications, N immobilisation, net N uptake in forests, denitrification and in-lake N retention were estimated for each group of lakes. Altogether, the long-term N sinks constituted 9.9 ± 3.2 to 40.5 ± 11.4 meq m-2yr-1 in the lowest and highest N deposition categories, respectively. At most sites, the current N deposition exceeds the amount of N retained by long-term sustainable N sinks plus the NO3‾ loss via the lake outlets. This excess N, which is currently retained within the catchments may, according to the FAB model, leach as acidifying NO3‾ in the future. If these predictions are fulfilled, NO3‾ leaching at sites in the various N deposition categories will increase dramatically from present (1995) mean levels of 1-20 meq m-2yr-1, to mean levels of 7-70 meq m-2yr-1 at future steady state. To illustrate the significance of such an increase in NO3‾ leaching, the mean Acid Neutralising Capacity (ANC) at sites in the highest N deposition category may decrease from -18 ± 15 μeq L-1 at present, to -40 ± 20 μeq L-1. Under present S and N deposition levels, the FAB model predicts that 46% of the Norwegian lakes may experience exceedances of critical loads for acidifying deposition. In comparison, the Steady-State Water Chemistry model (SSWC), which considers only the present N leaching level, estimates critical load exceedances in 37% of the lakes under the same deposition level. Thus far, there are great uncertainties regarding both the time scales and the extent of future N leaching, and it is largely unknown whether the FAB model predictions will ever be fulfilled. Hence, long-term monitoring and further studies on N immobilisation processes under varying N deposition levels and ecosystem types seem necessary to make better predictions of future NO3‾ leaching. Keywords: Lakes, hydrochemistry, nitrogen, nitrate, sinks, leaching, acidification, critical loads, FAB model

Sign in / Sign up

Export Citation Format

Share Document