[1] Norwegian Inst Air Res, NO-2027 Kjeller, Norway
[2] Univ Oslo, Dept Chem, NO-0315 Oslo, Norway
[3] Univ Lancaster, Lancaster Environm Ctr, Lancaster LA1 4YQ, England
[4] Chinese Acad Sci, Guangzhou Inst Geochem, Guangzhou 510640, Guangdong, Peoples R China