es5b03416_si_002.xlsx (102.67 kB)
Declining Dioxin Concentrations in the Rhone River Basin, France, Attest to the Effectiveness of Emissions Controls
dataset
posted on 2015-11-03, 00:00 authored by Peter C. Van Metre, Marc Babut, Brice Mourier, Barbara J. Mahler, Gwenaelle Roux, Marc DesmetEmission-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.