title: Canopy interaction with precipitation and sulphur deposition in two boreal forests of Quebec, Canada.
abstract: The interaction of atmospheric sulphur (S) was investigated within the canopies of two boreal forests in Québec, Canada. The net canopy exchange approach, i.e. the difference between S-SO(4) in throughfall and precipitation, suggests high proportion of dry deposition in winter (up to 53%) as compared to summer (1-9%). However, a 3.5‰ decrease in δ(18)O-SO(4) throughfall in summer compared to incident precipitation points towards a much larger proportion of dry deposition during the warm season. We suggest that a significant fraction of dry deposition (about 1.2 kg ha(-1) yr(-1), representing 30-40% of annual wet S deposition) which contributed to the decreased δ(18)O-SO(4) in throughfall was taken up by the canopy. Overall, these results showed that, contrary to what is commonly considered, S interchanges in the canopy could be important in boreal forests with low absolute atmospheric S depositions.
authors.affiliation: Environment Canada, Science and Technology Branch, Montreal, Québec, Canada. charles.marty@gmail.com
authors.forename: C
authors.initials: C
authors.lastname: Marty
authors.forename: D
authors.initials: D
authors.lastname: Houle
authors.forename: L
authors.initials: L
authors.lastname: Duchesne
authors.forename: C
authors.initials: C
authors.lastname: Gagnon
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000378:metabolism*; D002170:Canada; D004784:Environmental Monitoring; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D011792:Quebec; D012621:Seasons; D013455:Sulfur / Q000032:analysis / Q000378:metabolism*; D014197:Trees / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000393:Air Pollutants; D013455:Sulfur