| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4698285 | Chemical Geology | 2016 | 10 Pages |
•We reconstructed industrial and urban mercury (Hg) emissions recorded in the sediment of Lake Luitel over the last 150 year.•We provide a constrained age model with Hg accumulation rates (AR), Hg isotopic composition and exhaustive historical data.•Hg mass independent fractionation (MIF) signature reflect a global pool of industrial and urban emissions•Hg mass dependent fractionation (MDF) signatures allow the identification of major contributors.•Hg isotopic data combined with historical & chemical data is relevant for the historical reconstruction of Hg emissions.
This study reconstructs the history of multiple industrial and urban mercury (Hg) emissions recorded in the sediment archive of Lake Luitel (France) from AD ~ 1860 to AD 2011. For this purpose, we provide a well constrained short-lived radionuclides continuous age–depth relationship of the sediment sequence (mean accumulation rate of 5.18 ± 0.28 mm·yr− 1) with Hg accumulation rates (Hg AR), Hg isotopic composition and extensive historical data. Hg AR were stable around 45 μg·m− 2·y− 1 from 1860 to WWI and rose to reach their maximum at the end of WWII (250 μg m− 2 y− 1) followed by a gradual decreased to reach about 90 μg m− 2 y− 1 in the current period. Normalization to a terrigenous Hg proxy highlighted the dominance of atmospheric Hg inputs to the lake. The combination of Hg AR with isotopic signatures through the use of binary mixing (Δ199Hg vs 1/Hg AR) models and isotopic plots (and comparison to literature data) allowed us to identify the main industrial and urban historical inputs. The major outcome of this study is that the Hg mass independent fractionation (MIF) signature did not enable the identification of particular anthropogenic sources but reflected an integrated pool of industrial and urban emissions which tend to shift to less negative MIF values (mean: − 0.15 ± 0.04‰) during their period of maximum emissions. Temporal MIF and Hg AR variations depict the rising Hg emissions from the industrial revolution (1860–1910) to the modern industrial and urban development period (1950–1980). Mass dependent fractionation (MDF) signatures enabled the identification of major contributors in relation to their relative intensities lying between two endmember pools: (i) the combustion activities (smelters, cement factories and urban heating) with more negative δ202Hg values, and (ii) the chemical and electrometallurgical activities (electrochemistry, chlor-alkali) with higher δ202Hg values. Unconformities of MIF and MDF signatures were observed during WWI, WWII and interwar period, and were attributed to drastic and rapid changes in regional industrial activities. Finally, recent laws regarding Hg emissions (1998–2011) prove their efficiency as Hg AR decreased with a return to more negative MIF and MDF signatures such as during the industrial revolution period. Our study highlights that the combination of Hg isotopic data with Hg AR in sediment archives is a useful tool for reconstructing the history of anthropogenic Hg emissions, and has the potential to identifiy their relative contributions.
