title: Recent decline of DDTs among several organochlorine pesticides in background air in East Asia.
abstract: Hexachlorocyclohexanes (HCHs), chlordanes (CHLs), and dichlorodiphenyltrichloroethanes (DDTs) in air-mass outflows from East Asia were recorded monthly from April 2009 to March 2014 at Cape Hedo in Japan. These organochlorine pesticides (OCPs) were collected by a high volume air sampler equipped with a quartz fiber filter, a polyurethane foam plug, and activated carbon fiber and analyzed by using a gas chromatograph-high resolution mass spectrometer. The overall (and geometric mean ± SD) concentration over the period was 4.9-43 pg m(-3) (15 ± 7.8 pg m(-3)) in HCHs (sum of α-/β-/γ-/δ-HCH), 1.5-83 pg m(-3) (8.8 ± 11 pg m(-3)) in CHLs (sum of cis-/trans-chlordane, cis-/trans-nonachlor, and oxychlordane), and 0.71-16 pg m(-3) (2.5 ± 2.0 pg m(-3)) in DDTs (sum of o,p'-/p,p'-DDD, o,p'-/p,p'-DDE, and o,p'-/p,p'-DDT). Clear seasonal changes, i.e. higher in summer and lower in winter, were observed in HCHs and CHLs, suggesting the dominant effect of temperature-dependence, secondary sources in these OCPs. DDT concentration as well as the ratio of (o,p'-DDT + p,p'-DDT) to total DDTs, on the other hand, showed clear a declining trend during the five year sampling period, suggesting the decrease of input of newly produced DDTs in the regional environment by reflecting recent activities in the East Asian region to eliminate production and use of DDTs under the Stockholm Convention.
authors.affiliation: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. Electronic address: takazawa@nies.go.jp.
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Takazawa
authors.affiliation: Shimadzu Techno-Research, Inc., 1 Nishinokyo-shimoaicho, Nakagyo-ku, Kyoto 604-8436, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Takasuga
authors.affiliation: Ministry of the Environment of Japan, 1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8975, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Doi
authors.affiliation: Ministry of the Environment of Japan, 1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8975, Japan.
authors.forename: Mick
authors.initials: M
authors.lastname: Saito
authors.affiliation: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shibata
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D003634:DDT / Q000032:analysis*; D004784:Environmental Monitoring; D005202:Asia, Eastern; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D012621:Seasons; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D003634:DDT
keywords: Air monitoring; Background site; Cape Hedo; Organochlorine pesticide; Temporal trend