Impact of the North Atlantic Oscillation on Swedish Winter Climate and Nutrient Leaching

• Published in: Journal of Environmental Quality
• Main Authors: Ulén, Barbro, Lewan, Elisabet, Kyllmar, Katarina, Blomberg, Maria, Andersson, Stefan
• Other Authors: Naturvårdsverket
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Management, Monitoring, Policy and Law; Pollution; Waste Management and Disposal; Water Science and Technology; Environmental Engineering; North Atlantic; North Atlantic oscillation
• Online Access: http://dx.doi.org/10.2134/jeq2018.06.0237; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2134%2Fjeq2018.06.0237; https://onlinelibrary.wiley.com/doi/pdf/10.2134/jeq2018.06.0237; https://onlinelibrary.wiley.com/doi/full-xml/10.2134/jeq2018.06.0237

The winter climate in northwestern Europe is commonly influenced by the North Atlantic Oscillation (NAO). Its intensity, expressed as an index (NAO i ), has been suggested for use in assessing nutrient leaching from arable land to water and the effects of mitigation measures. We found significant ( p < 0.05) positive linear relationships between NAO i and an air freezing–thawing index in central and southern Sweden for 2004 to 2016. This period covered winters with both extreme low and high NAO i . There were significant negative linear relationships between NAO i and a snow depth index. Management and nutrient leaching were studied simultaneously in two agricultural catchments (20.7 ha, code 11M; 788 ha, code M36) in southwestern Sweden. Catchments 11M (silty–clay soil) and M36 (sandy hills with a central, heavy clay plain) are both artificially drained. Total N and total P leaching increased significantly with winter (November–April) NAO i in both catchments. In contrast, leaching of dissolved reactive P (DRP) was not related to NAO i . The highest DRP concentrations were observed in connection with specific agricultural practices, whereas moderately elevated DRP concentrations were linked to snowmelt events. Concentrations of P in other forms (other P) were even more elevated (1.02 mg L −1 ) in 11M in winter 2014–2015, probably due to a large (32% of area) internal buffer (ley–fallow) in a central ravine being plowed down in autumn 2014. No general trend in P or N fertilization was found in catchment M36. Thus NAO i may be appropriate for use in trend analyses of nutrient load in the study region. Core Ideas North Atlantic Oscillation (NAO) intensity index (NAO i ) influences annual winter climate. NAO i has an impact on regional nutrient leaching. Moderate particle P leaching may reflect low NAO i and high snow depth index. NAO i influences erosion less than ploughing down strategic unfertilized buffer zones.