The issues involved in assessing and evaluating Critical Levels for atmospheric NH3 and vegetation are discussed, recognizing that measurable effects of exposure to NH3 may be observed in plant species without necessarily any adverse effects on that species. Consequently, impacts of NH3 are best measured in terms of community response, where there is a measurable change in species composition and/or loss of individual species. Such data are currently available only from field measurements, either from measurements close to point sources, where NH3 concentrations have also been measured, or from controlled field fumigation experiments. The relationship between Critical Levels and Critical Loads is explored, and the redundancy of the 1993 Critical Level (8 µg m−3 as an annual average), when compared with the Critical Loads for N deposition, is demonstrated. Statistical techniques for estimating ‘no effect’ concentrations from field measurements are presented, and then used to review the available data. For sensitive vegetation types (lichens and bryophytes) field evidence shows changes in species composition at NH3 concentrations (as an annual average) of 1 µg m−3, which is proposed as the new Critical Level for annual average NH3 concentrations for sensitive ecosystems (i.e. those in which lichens and bryophytes are important components). There are fewer data for higher plants, but a Critical Level of 3 µg m−3 is proposed, as a long-term average NH3 concentration. The existing Critical Level of 23 µg m−3 for the monthly average concentration is retained, given the recent changes in seasonal patterns of NH3 emissions from agricultural practices such as slurry spreading.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Frati L., Santoni S,. Nicolardi V., Gaggi C., Brunialti G., Guttova A., Gaudino S., Pati A., Pirintsos S.A., Loppi. S. (2006) Lichen biomonitoring of ammonia emission and nitrogen deposition around a pig stockfarm. Environmental Pollution 146 (2), 311–316.
Leith I.D., van Dijk N., Pitcairn C.E.R., Wolseley P.A., Whitfield C.P., Sutton M.A. (2005) Biomonitoring methods for assessing the impacts of nitrogen pollution: Refinement and testing, 290, JNCC Report No. 386, Peterborough.
Pinho P., Branquinho C., Cruz C. Tang Y.S., Dias T., Rosa A.P., Máguas C., Loução M.A.M., Sutton M.A. (2009) Assessment of critical levels of atmospheric ammonia for lichen diversity in cork-oak woodland, Portugal. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 10).
Pitcairn C.E.R., Leith I.D., Sheppard L.J., Sutton M.A. (2006) Development of a nitrophobe/ nitrophile classification for woodlands, grasslands and upland vegetation in Scotland, 21, Centre for Ecology & Hydrology, Penicuik, UK.
Pitcairn C.E.R., Leith I.D., van Dijk N., Sheppard L.J., Sutton M.A., Fowler D. (2009) The application of transects to assess the effects of ammonia on woodland groundflora. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 5).
Rihm B., Urech M., Peter K. (2009) Mapping ammonia emissions and concentrations for Switzerland—effects on lichen vegetation. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 7).
Sheppard L.J., Leith I.D., Crossley A., van Dijk N., Cape J.N., Fowler D., Sutton M.A. (2009) Long-term cumulative exposure exacerbates the effects of atmospheric ammonia on an ombro-trophic bog: Implications for Critical Levels. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 4).
Sutton M.A., Leith I.D., Pitcairn C.E.R., van Dijk N., Tang Y.S., Sheppard L., Dragosits U., Fowler D., James P.W., Wolseley P.A. (2004a) Exposure of ecosystems to atmospheric ammonia in the UK and the development of practical bioindicator methods. In: Lambley, P. & Wolseley, P.A. (eds.), Lichens in a Changing Environment. English Nature Research Report No. 525. English Nature, Peterborough.
Sutton M.A., Pitcairn C.E.R., Leith I.D., van Dijk N., Tang Y.S., Skiba U., Smart S., Mitchell R., Wolseley P., James P., Purvis W., Fowler D. (2004b) Bioindicator and biomonitoring methods for assessing the effects of atmospheric nitrogen on statutory nature conservation sites. Edited by M.A. Sutton, C.E.R. Pitcairn & C.P. Whitfield. JNCC Report No. 356, Peterborough.
Sutton M.A., Wolseley P.A., Leith I.D., van Dijk N., Tang Y.S., James P.W., Theobald M.R., Whitfield C. (2009a) Estimation of the ammonia critical level for epiphytic lichens based on observations at farm, landscape and national scales. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 6).
Sutton M.A., van Pul W.A.J., Sauter F., Tang Y.S., Horvath L. (2009b) Over which averaging period is the ammonia critical level most precautionary? In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop Under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 8).
Wolseley P.A., James P.W., Theobald M. R., Sutton M.A. (2006) Detecting changes in epiphytic lichen communities at sites affected by atmospheric ammonia from agricultural sources. The Lichenologist 38: 161–176.
Wolseley P.A., Leith I.D., van Dijk N., Sutton M.A. (2009) Machrolichens on twigs and trunks as indicators of ammonia concentrations across the UK—a practical method. In: Sutton M.A., Reis S., Baker S.M.H. (eds.), Atmospheric Ammonia—Detecting Emission Changes and Environmental Impacts. Results of an Expert Workshop under the Convention on Long-range Transboundary Air Pollution. Springer (Chapter 9).
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2009 Springer Science + Business Media B.V.
About this chapter
Cite this chapter
Cape, J.N. et al. (2009). Critical Levels for Ammonia. In: Sutton, M.A., Reis, S., Baker, S.M. (eds) Atmospheric Ammonia. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-9121-6_22
Download citation
DOI: https://doi.org/10.1007/978-1-4020-9121-6_22
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-9120-9
Online ISBN: 978-1-4020-9121-6
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)