U.S. Geological Survey, 1505 Ferguson Lane, Austin, Texas 78754, United States.
IRSTEA, UR MALY, 5 rue de la Doua, CS 70077, F-69626 Villeurbanne, France.
Environ Sci Technol. 2015 Nov 3;49(21):12723-30. doi: 10.1021/acs.est.5b03416. Epub 2015 Oct 19.
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.
自 20 世纪 90 年代以来，欧洲和北美实施了排放控制政策，以控制多氯二苯并对二恶英（PCDDs）和呋喃（PCDFs）的排放。为了评估这些政策对欧洲一个大型河流系统中这些化合物的时间趋势和空间分布模式的影响，在法国罗纳河的七个沉积区采集了沉积岩芯，对其进行了定年，并分析了 PCDDs 和 PCDFs。结果表明，在过去的二十年中，所有地点的浓度都呈下游方向增加，且在时间上呈下降趋势，与 1992 年相比，2010 年的平均降幅为 83%。浓度下降 50%所需的时间（t1/2），分别为所有测量的 PCDDs 和 PCDFs 的总和的 6.9±2.6 和 9.1±2.9 年。核心之间的同系物模式相似，表明区域大气沉降和可能风化的本地源占主导地位。在最下游的地点，最毒的二恶英 TCDD 的浓度比其他六个地点高约 2 个数量级，明显表明存在本地源。相对陡峭的下降趋势证明了欧洲减少二恶英排放政策的效果，并表明罗纳河流域水生生物面临的二恶英和呋喃的风险已大大降低。
