title: Distribution characteristics of organochlorine pesticides in surface and vertical sediments from the Zha Long Wetland, China.
abstract: BACKGROUND
  The Zha Long Wetland, the first water bird conservation area in China, lies on the northern bank of the Song Nen Plain with an area of 2,100 km(2). In many areas of the Zha Long Wetland, water pollution has led to a decrease in the wetland's ecological function, vegetation degradation, a decrease in the number of bird species, and the depletion of fish resources.
  
  
  METHODS
  The sediments used in this study were collected from the surface sediment of seven sites and from different depths in three types of marshes in the Zha Long Wetland in northeast China in late October 2006. The levels and distribution patterns of 17 organochlorine pesticides (OCPs; α-HCH, β-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, p,p'-DDT, endosulfan I, endosulfan II, endosulfan sulfate, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, and methoxychlor) in surface sediments as well as hexachlorocyclohexane (HCH) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) in vertical sediments were investigated.
  
  
  CONCLUSIONS
  The concentrations of HCHs, DDTs, endosulfans, heptachlors, aldrin, and methoxychlor in surface sediments ranged from 10.44 to 41.97 ng/g, nd (undetectable levels) to 211.88 ng/g, nd to 69.89 ng/g, nd to 28.10 ng/g, 9.81 to 623.83 ng/g, and from nd to 3.99 ng/g, respectively. The highest levels of OCPs were detected in Tangtugangzi at a total concentration of 727.72 ng/g, where the dominant compound was endrin at a concentration of 483.04 ng/g. In the vertical sediments, the HCHs and DDTs were in the ranges of nd-136.00 and nd-214.06 ng/g, respectively.
  
  
  CONCLUSIONS
  Different distributions of HCHs, DDTs, and other OCPs indicated that they originated from different contamination sources. Composition analyses in surface sediments indicated recent OCP usage or discharge at some sample sites in the Zha Long Wetland.
authors.affiliation: College of Material Science and Chemical Engineering, Harbin Engineering University, 145 Nantong Street, Nangang District, Harbin, Heilongjiang Province, 150001, People's Republic of China. liuguangmin@vip.sina.com
authors.forename: Guangmin
authors.initials: G
authors.lastname: Liu
authors.forename: Jinchunzi
authors.initials: J
authors.lastname: Li
authors.forename: Lili
authors.initials: L
authors.lastname: Yin
authors.forename: Liyan
authors.initials: L
authors.lastname: Liu
authors.forename: Hong
authors.initials: H
authors.lastname: Qi
authors.forename: Yining
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000383:Agriculture; D000818:Animals; D001717:Birds; D002681:China; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring / Q000379:methods; D005399:Fishes; D019015:Geologic Sediments / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry*; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D053833:Wetlands
chemical_list: D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D014874:Water Pollutants, Chemical