Crop harvest in Denmark and Central Europe contributes to the local load of airborne <i>Alternaria</i> spore concentrations in Copenhagen

Abstract

Abstract. This study examines the hypothesis that Danish agricultural areas are the main source of airborne Alternaria spores in Copenhagen, Denmark. We suggest that the contribution to the overall load is mainly local or regional, but with intermittent long distance transport (LDT) from more remote agricultural areas. This hypothesis is supported by investigating a 10 yr bi-hourly record of Alternaria spores in the air from Copenhagen. This record shows 232 clinically relevant episodes (daily average spore concentration above 100 m −3 ) with a distinct daily profile. The data analysis also revealed potential LDT episodes almost every year. A source map and analysis of atmospheric transport suggest that LDT always originates from the main agricultural areas in Central Europe. A dedicated emission study in cereal crops under harvest during 2010 also supports our hypothesis. The emission study showed that although the fields had been treated against fungal infections, harvesting still produced large amounts of airborne fungal spores. It is likely that such harvesting periods can cause clinically relevant levels of fungal spores in the atmosphere. Our findings suggest that crop harvest in Central Europe causes episodes of high airborne Alternaria spore concentrations in Copenhagen as well as other urban areas in this region. It is likely that such episodes could be simulated using atmospheric transport models.

Alternaria spores in the air across Europe: abundance, seasonality and relationships with climate, meteorology and local environment

“…• Alternaria -Cause respiratory allergies [1,2] -Important plant pathogens [3,4] -Considered associated with agricultural landscapes [5,6] • Complicating factors -More than 300 species [7] -May -or may not be-host specific [8] -Emissions of Alternaria spores can be substantial [5,9] -Emissions process of Alternaria can be both natural and man made [5] -Little is known on Alternaria compared to pollen, e.g. lack of area-wide assessments, fewer observations, fewer models, no source maps .. spores not addressed by EUPOL.…”

Atmospheric concentrations of Alternaria, Cladosporium, Ganoderma and Didymella spores monitored in Cork (Ireland) and Worcester (England) during the summer of 2010

“…Both spore types were in general found to have higher concentrations at daytime hours under drier conditions, low humidity and greater wind speeds. Recently, it has been shown that periods of dry weather during the harvesting season can promote high concentrations of fungal spores from the mechanical release of spores through harvesting machines (Skjøth et al 2012), where a considerable fraction of them can be transported several hundred kilometres away. This mechanism seems to be related to ''dry'' spores as harvesting in general happens during dry weather.…”

A simple model describes development of early peaks in oomycete zoospore inoculum detected in southern UK outdoors horticultural reservoirs

“…The approach of matching nearby meteorological stations has worked well in a number of studies on airborne spores [10] and pollen [11] when the focus is on overall climate in specific regions of Europe including the UK (e.g., [12]). Here the assumption that the mean monthly air temperature reflects the temperature in the aquatic environment in the nurseries assessed seems also to have worked well.…”