title: Declining Dioxin Concentrations in the Rhone River Basin, France, Attest to the Effectiveness of Emissions Controls.
abstract: Emission-control policies have been implemented in Europe and North America since the 1990s for polychlorodibenzodioxins (PCDDs) and furans (PCDFs). To assess the effect of these policies on temporal trends and spatial patterns for these compounds in a large European river system, sediment cores were collected in seven depositional areas along the Rhone River in France, dated, and analyzed for PCDDs and PCDFs. Results show concentrations increase in the downstream direction and have decreased temporally at all sites during the last two decades, with an average decrease of 83% from 1992 to 2010. The time for a 50% decrease in concentrations (t1/2) averaged 6.9±2.6 and 9.1±2.9 years for the sum of measured PCDDs and PCDFs, respectively. Congener patterns are similar among cores and indicate dominance of regional atmospheric deposition and possibly weathered local sources. Local sources are clearly indicated at the most downstream site, where concentrations of the most toxic dioxin, TCDD, are about 2 orders of magnitude higher than at the other six sites. The relatively steep downward trends attest to the effects of the dioxin emissions reduction policy in Europe and suggest that risks posed to aquatic life in the Rhone River basin from dioxins and furans have been greatly reduced.
authors.affiliation: U.S. Geological Survey, 1505 Ferguson Lane, Austin, Texas 78754, United States.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Van Metre
authors.affiliation: IRSTEA, UR MALY, 5 rue de la Doua, CS 70077, F-69626 Villeurbanne, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Babut
authors.affiliation: Université Lyon 1, UMR 5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, 3, Rue Maurice Audin, F-69518 Vaulx-en-Velin, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Mourier
authors.affiliation: U.S. Geological Survey, 1505 Ferguson Lane, Austin, Texas 78754, United States.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Mahler
authors.affiliation: Université Lyon 1, UMR 5023 Ecologie des Hydrosystèmes Naturels et Anthropisés, ENTPE, CNRS, 3, Rue Maurice Audin, F-69518 Vaulx-en-Velin, France.
authors.forename: Gwenaelle
authors.initials: G
authors.lastname: Roux
authors.affiliation: Université de Tours, GéHCO EA 6293, F-37000 Tours, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Desmet
mesh_terms: D004147:Dioxins / Q000032:analysis*; D005602:France; D005663:Furans / Q000032:analysis; D000072317:Polychlorinated Dibenzodioxins / Q000032:analysis; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004147:Dioxins; D005663:Furans; D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical