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Daniel Obrist - One of the best experts on this subject based on the ideXlab platform.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2014
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    Sediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM—and for Hg due to their close associations—in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2013
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    International audienceSediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM--and for Hg due to their close associations--in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments

Marc Lucotte - One of the best experts on this subject based on the ideXlab platform.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2014
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    Sediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM—and for Hg due to their close associations—in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2013
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    International audienceSediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM--and for Hg due to their close associations--in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments

  • translocation of soil organic matter following Reservoir Impoundment in boreal systems implications for in situ productivity
    Limnology and Oceanography, 2006
    Co-Authors: Stephane Houel, Marc Lucotte, René Canuel, Patrick Louchouarn, Bassam Ghaleb
    Abstract:

    To evaluate the effect of Reservoir flooding on carbon cycling over time, we studied sedimentary environments in three natural lakes that existed prior to Impoundment and that have been incorporated in the larger lentic system of a 70-yr-old boreal Reservoir in Quebec. Elemental and biomarker analyses were determined in all core intervals and three soil profiles to characterize source inputs of organic matter to sediments. Following Impoundment, a twoto threefold increase in lignin concentrations (5 to 10‐25 mg [10 g dry wt] 21 ) associated with similar decreases in selected terrigenous biomarker ratios (cinnamyl phenols : vanillyl phenols, C : V, 1.0‐2.0 to 0.2‐0.5; 3,5-dihydroxybenzoic acid : vanillyl phenols, 3,5-Bd : V, 0.2‐0.5 to 0.1‐0.2; and p-hydroxyl phenols : sum of vanillyl and syringyl phenols, P : [V1S], 0.3‐0.7 to 0.1‐0.4) illustrate the effect of soil erosion and subsequent translocation of surface soil organic matter (SOM) to sedimentary deposits. Using a mixing model based on mass-normalized biomarker yields in identified surface and mineral soil end-members, we show that although the proportion of mineral-derived SOM predominates in the receiving sedimentary systems during preflooding conditions (97‐99% of allochthonous inputs), translocated surface SOM increased in postflooding sediments to comprise up to 5‐30% of the total allochthonous organic matter inputs. Using a similar quantitative mixing model based on elemental C and N contents in the autochthonous and the mixed allochthonous end-members, we estimated that concomitant to the redistribution of eroded soil organic matter, Reservoir flooding induces a 1.5- to 2-fold increase in the fraction of autochthonous organic matter transferred to sedimentary environments of the Reservoir. Results presented here suggest that Reservoir flooding induces a change of state in lake systems that may perdure over time scales of decades to centuries.

René Canuel - One of the best experts on this subject based on the ideXlab platform.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2014
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    Sediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM—and for Hg due to their close associations—in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2013
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    International audienceSediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM--and for Hg due to their close associations--in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments

  • translocation of soil organic matter following Reservoir Impoundment in boreal systems implications for in situ productivity
    Limnology and Oceanography, 2006
    Co-Authors: Stephane Houel, Marc Lucotte, René Canuel, Patrick Louchouarn, Bassam Ghaleb
    Abstract:

    To evaluate the effect of Reservoir flooding on carbon cycling over time, we studied sedimentary environments in three natural lakes that existed prior to Impoundment and that have been incorporated in the larger lentic system of a 70-yr-old boreal Reservoir in Quebec. Elemental and biomarker analyses were determined in all core intervals and three soil profiles to characterize source inputs of organic matter to sediments. Following Impoundment, a twoto threefold increase in lignin concentrations (5 to 10‐25 mg [10 g dry wt] 21 ) associated with similar decreases in selected terrigenous biomarker ratios (cinnamyl phenols : vanillyl phenols, C : V, 1.0‐2.0 to 0.2‐0.5; 3,5-dihydroxybenzoic acid : vanillyl phenols, 3,5-Bd : V, 0.2‐0.5 to 0.1‐0.2; and p-hydroxyl phenols : sum of vanillyl and syringyl phenols, P : [V1S], 0.3‐0.7 to 0.1‐0.4) illustrate the effect of soil erosion and subsequent translocation of surface soil organic matter (SOM) to sedimentary deposits. Using a mixing model based on mass-normalized biomarker yields in identified surface and mineral soil end-members, we show that although the proportion of mineral-derived SOM predominates in the receiving sedimentary systems during preflooding conditions (97‐99% of allochthonous inputs), translocated surface SOM increased in postflooding sediments to comprise up to 5‐30% of the total allochthonous organic matter inputs. Using a similar quantitative mixing model based on elemental C and N contents in the autochthonous and the mixed allochthonous end-members, we estimated that concomitant to the redistribution of eroded soil organic matter, Reservoir flooding induces a 1.5- to 2-fold increase in the fraction of autochthonous organic matter transferred to sedimentary environments of the Reservoir. Results presented here suggest that Reservoir flooding induces a change of state in lake systems that may perdure over time scales of decades to centuries.

Vineet K. Gahalaut - One of the best experts on this subject based on the ideXlab platform.

  • Effect of the Zipingpu Reservoir Impoundment on the occurrence of the 2008 Wenchuan earthquake and local seismicity
    Geophysical Journal International, 2010
    Co-Authors: Kalpna Gahalaut, Vineet K. Gahalaut
    Abstract:

    SUMMARY The occurrence of the 2008 May 12 Wenchuan earthquake (M 7.9) near the eastern edge of the Tibetan Plateau triggered a debate whether it was influenced by the newly impounded Zipingpu Reservoir, located only about 21 km east of the earthquake epicentre. We calculated change in stresses due to the 3-D Reservoir water load using Boussinesq theory and pore pressure diffusion due to the actual variation of water level in the Reservoir. Using the stresses and pore pressure due to the Reservoir Impoundment, we calculated the Coulomb stress on the NW dipping fault plane of the 2008 Wenchuan earthquake. We find that the Reservoir operation did not cause any increase in the Coulomb stress at the earthquake hypocentre and the region around it, rather it decreased the stress by a nominal amount of about 1 KPa. Thus, we suggest that the Reservoir probably did not play a role in the occurrence of this earthquake. However, our analysis suggests that the slightly enhanced low-magnitude shallow seismicity after the Reservoir Impoundment, but prior to the 2008 Wenchuan earthquake, was positively influenced by the Reservoir Impoundment.

Roman Teisserenc - One of the best experts on this subject based on the ideXlab platform.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2014
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    Sediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM—and for Hg due to their close associations—in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments.

  • Combined dynamics of mercury and terrigenous organic matter following Impoundment of Churchill Falls Hydroelectric Reservoir, Labrador
    Biogeochemistry, 2013
    Co-Authors: Roman Teisserenc, Marc Lucotte, René Canuel, Matthieu Moingt, Daniel Obrist
    Abstract:

    International audienceSediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of Reservoir Impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM--and for Hg due to their close associations--in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of Reservoir Impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded Reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the Reservoirs. The fact that T-[Hg] was still enriched 40 years after Reservoir Impoundment indicates prolonged response time of lake Hg and sediment loadings after Reservoir Impoundments