Current atmospheric nitrogen deposition still exceeds critical loads for sensitive, semi-natural ecosystems in Switzerland

Kosonen, Zaida and Schnyder, Elvira and Hiltbrunner, Erika and Thimonier, Anne and Schmitt, Maria and Seitler, Eva and Thoeni, Lotti. (2019) Current atmospheric nitrogen deposition still exceeds critical loads for sensitive, semi-natural ecosystems in Switzerland. ATMOSPHERIC ENVIRONMENT, 211. pp. 214-225.

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Official URL: https://edoc.unibas.ch/74352/

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Increased atmospheric nitrogen (N) deposition is driving nutrient imbalances, soil acidification, biodiversity losses and the long-term reduction in stability of sensitive ecosystems which previously had limited N. In this study, we analysed the concentrations of seven different N compounds in precipitation and in the air at 34 sites across Switzerland. We calculated the N deposition by precipitation (bulk deposition) and applied the inferential method to derive dry deposition (gases, aerosols) from air concentrations. We then quantified the total inorganic N deposition by adding together the bulk and dry deposition. Finally, the total inorganic N input into the sensitive ecosystems of the 34 sites was compared to the critical loads of these ecosystems.N deposition by precipitation was the main contributor to the total N load in 16 out of 34 sites, especially into open ecosystems such as alpine/subalpine grassland, mountain hay meadows, and raised bogs. Dry deposition of ammonia (NH3) was the second most important pathway, in particular for forests close to agricultural activities, due to high NH3 concentrations and the higher deposition velocity. The N deposition exceeded the lower limit of the Critical Load of Nitrogen (CLN) range at most sites, and at many sites even surpassed the upper limit of the CLN range. No, or minor, exceedances of the critical loads for N were found only at remote sites at higher elevation in the Central Alps. Annual inorganic N deposition between 2000 and 2017 revealed a significant decline in oxidised N compounds at four of five sites (-1.6-1.8% per year), but reduced compounds only decreased at two sites (-1% and -1.4% per year) and even increased at one site (+1.2% per year), despite adopted abatement strategies for agricultural practices. This emphasises that most sensitive ecosystems in Switzerland continue to be exposed to excessive N loads through atmospheric deposition, with detrimental consequences for the biodiversity and stability of these ecosystems.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Integrative Biologie > Physiological Plant Ecology (Kahmen)
UniBasel Contributors:Hiltbrunner, Erika
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:27 May 2020 09:59
Deposited On:27 May 2020 09:59

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