title: Assessment of organochlorine pesticide levels in Manadas Creek, an urban tributary of the Rio Grande in Laredo, Texas.
abstract: The Rio Grande is the natural boundary between the United States and Mexico from El Paso, Texas, to Brownsville, Texas. It supports about 12 million people on both sides of the border for municipal, agricultural, industrial, and recreational uses. The rapid population and economic growth along the border region has led to increased pollution in the Rio Grande, which has been linked to several border health issues associated with pesticide contamination. This project was initiated to assess the organochlorine pesticide levels in the water and sediments in Manadas Creek, an urban tributary of the Rio Grande located in north Laredo, Texas. Water and sediment samples were collected monthly during a 6-month period from July to December of 2006 and analyzed using gas chromatography with an electron capture detector after extraction via a solid-phase microextraction technique. Among the water and sediment samples collected, several organochlorine pesticides including alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), heptachlor epoxide, endrin, and 4,4'-DDT were found in either the creek water or sediments. Analysis of variance results indicated that only gamma-HCH had significant variation in the creek water among the sampling periods. Comparison of results with previous findings showed the presence of higher levels of HCH isomers and much lower DDT concentrations in the present study.
authors.affiliation: Department of Environmental Engineering, Texas A&M University-Kingsville, 78363-8202, USA.
authors.forename: Brianna
authors.initials: B
authors.lastname: Flores
authors.forename: Celina
authors.initials: C
authors.lastname: Camarena
authors.forename: Jianhong
authors.initials: J
authors.lastname: Ren
authors.forename: Sushma
authors.initials: S
authors.lastname: Krishnamurthy
authors.forename: Wayne
authors.initials: W
authors.lastname: Belzer
mesh_terms: D000818:Animals; D002947:Cities; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D006534:Heptachlor Epoxide / Q000032:analysis; D001556:Hexachlorocyclohexane / Q000032:analysis; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D013781:Texas; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D014874:Water Pollutants, Chemical; D006534:Heptachlor Epoxide; C040534:alpha-hexachlorocyclohexane; D001556:Hexachlorocyclohexane; C023888:beta-hexachlorocyclohexane