title: Chiral chemicals as tracers of atmospheric sources and fate processes in a world of changing climate.
abstract: Elimination of persistent organic pollutants (POPs) under national and international regulations reduces "primary" emissions, but "secondary" emissions continue from residues deposited in soil, water, ice and vegetation during former years of usage. In a future, secondary source controlled world, POPs will follow the carbon cycle and biogeochemical processes will determine their transport, accumulation and fate. Climate change is likely to affect mobilisation of POPs through e.g., increased temperature, altered precipitation and wind patterns, flooding, loss of ice cover in polar regions, melting glaciers, and changes in soil and water microbiology which affect degradation and transformation. Chiral compounds offer advantages for following transport and fate pathways because of their ability to distinguish racemic (newly released or protected from microbial attack) and nonracemic (microbially degraded) sources. This paper discusses the rationale for this approach and suggests applications where chiral POPs could aid investigation of climate-mediated exchange and degradation processes. Multiyear measurements of two chiral POPs, trans-chlordane and α-HCH, at a Canadian Arctic air monitoring station show enantiomer compositions which cycle seasonally, suggesting varying source contributions which may be under climatic control. Large-scale shifts in the enantioselective metabolism of chiral POPs in soil and water might influence the enantiomer composition of atmospheric residues, and it would be advantageous to include enantiospecific analysis in POPs monitoring programs.
authors.affiliation: Chemistry Department, Umeå University ; Centre for Atmospheric Research Experiments, Environment Canada.
authors.forename: Terry
authors.initials: T
authors.lastname: F Bidleman
authors.affiliation: Centre for Atmospheric Research Experiments, Environment Canada.
authors.forename: Liisa
authors.initials: L
authors.lastname: M Jantunen
authors.affiliation: Faculty of Engineering, Department of Environmental Engineering, Bahçeşehir University.
authors.forename: Perihan
authors.initials: P
authors.lastname: Binnur Kurt-Karakus
authors.affiliation: Department of Applied Environmental Science (ITM), Stockholm University.
authors.forename: Fiona
authors.initials: F
authors.lastname: Wong
authors.affiliation: Science & Technology Branch, Environment Canada.
authors.forename: Hayley
authors.initials: H
authors.lastname: Hung
authors.affiliation: Science & Technology Branch, Environment Canada.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Ma
authors.affiliation: Freshwater Institute, Department of Fisheries & Oceans 501 University Crescent ; Centre for Earth Observation Science, University of Manitoba.
authors.forename: Gary
authors.initials: G
authors.lastname: Stern
authors.affiliation: Freshwater Institute, Department of Fisheries & Oceans 501 University Crescent.
authors.forename: Bruno
authors.initials: B
authors.lastname: Rosenberg
keywords: air-surface exchange; atmospheric transport; chiral; climate change; persistent organic pollutants