Mercury transfer from watersheds to aquatic environments following the erosion of agrarian soils: A molecular biomarker approach

Caron, Sébastien; Lucotte, Marc; Teisserenc, Roman

doi:10.4141/cjss07112

Cited by 21 publications

(16 citation statements)

References 30 publications

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“…Several studies have observed that the levels of T-Hg transported to lakes are related to TOM concentration (Driscoll et al 1995;Kolka et al 1999;Kainz et al 2003;Sanei and Goodarzi 2006). More precisely, some studies raised the issue that TOM quality (source, composition), more than the sole quantity of TOM entering the lake, plays a key role in the fate of Hg in the environment Kainz and Lucotte 2006;Sanei and Goodarzi 2006;Caron et al 2008;Ouellet et al 2009). The regime of atmospheric Hg deposition on soil also varies according to vegetation (Schroeder and Munthe 1998;Demers et al 2007).…”

Section: Introductionmentioning

confidence: 97%

Terrestrial organic matter biomarkers as tracers of Hg sources in lake sediments

2010

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Terrestrial organic matter (TOM) plays a key role in mercury (Hg) dynamics between watersheds and lakes. In this study we attempts to determine the role of TOM source and quality and not only quantity, in the fate and transport of total Hg (T-Hg) to boreal lakes. Integrating the watershed complexity is a daunting task. Within the scope of this project, we characterized this organic matter at a molecular level in order to determine Hg transfer conditions to the sediments. We sampled ten lakes in the Quebec boreal forest. In each lake, we took a sediment core at the deepest point in addition to analyzing T-Hg and a set of terrigenous biomarkers in recent sediments. Our results show no relationship between TOM quantity and T-Hg concentration in lake sediments. However, [T-Hg] variation is well explained by the increase of 3,5Bd/V ratios (R 2 = 0.84; p \ 0.0002) and the decrease of C/V ratios (R 2 = 0.5; p \ 0.0227). Our study shows that TOM source and quality are determinant for Hg loadings in lake sediments. More precisely, increasing TOM derived from humified soil horizons explains most of Hg level variation within sediments.

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Section: Introductionmentioning

confidence: 97%

Terrestrial organic matter biomarkers as tracers of Hg sources in lake sediments

2010

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“…The use of lignin-derived phenols biomarkers to characterize lake water particulate organic matter (POM) and DOM is novel (Weissenberger 2007;Caron et al 2008). The aim of this research is to assess the role of terrigenous OM, using vascular plant-derived biomarkers, on Hg loadings in lakes.…”

Section: Introductionmentioning

confidence: 99%

Lignin biomarkers as tracers of mercury sources in lakes water column

et al. 2009

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This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r 2 = 0.62, p \ 0.0001; particulate OM r 2 = 0.76, p \ 0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition-angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems.

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“…First, it is less assimilated by invertebrates than epiphytes and macrophytes. Second, the MeHg concentrations in SPM are very low (Caron et al 2008), much lower in fact than those of the other OM sources. Third, we found no relationships between SPM proportion in consumer diet and Hg concentrations in the consumers.…”

Section: Links Between Hg Concentrations and Om Sourcesmentioning

confidence: 97%

“…Terrestrial OM inputs, illustrated partly in our study by SPM signature (Caron et al 2008), represented a smaller dietary resource for macroinvertebrate primary consumers in Lake St. Pierre. This is in agreement with a recent study by Clapcott and Bunn (2003), which reported low contributions of C 4 plants to aquatic food webs, despite their widespread distribution and production.…”

Section: Contribution Of the Om Sources To Macroinvertebrate Dietmentioning

confidence: 99%

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Sources of organic matter and methylmercury in littoral macroinvertebrates: a stable isotope approach

et al. 2009

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The main objective of this study was to assess organic matter (OM) and methylmercury (MeHg) sources for freshwater littoral macroinvertebrate primary consumers. The carbon and nitrogen stable isotope ratios (d 13 C, d 15 N) of sources (epiphytes, macrophytes, suspended particulate matter _SPM) and of macroinvertebrate consumers were measured in a fluvial lake with extensive macrophyte beds (emergent and submerged). To determine the relative contribution of each OM source to macroinvertebrate diets we used the IsoSource model that examines all possible combinations of solutions for each source. Total and MeHg concentrations of consumers were also measured. Results show that epiphytes and macrophytes are dominant in the diet of macroinvertebrates, especially in early summer (July). In mid-summer (August), SPM constitutes a non-negligible OM source to the primary consumers. Hg concentrations were higher in epiphytes than in the other OM sources. The proportion of epiphytes in macroinvertebrate diet was positively correlated with the percentage of MeHg in their tissues. There was no relationship between SPM assimilation and Hg concentration in macroinvertebrate consumers. These results suggest that epiphytes and macrophytes constitute the main pathway of Hg bioaccumulation in littoral food webs.

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Mercury transfer from watersheds to aquatic environments following the erosion of agrarian soils: A molecular biomarker approach

Cited by 21 publications

References 30 publications

Terrestrial organic matter biomarkers as tracers of Hg sources in lake sediments

Terrestrial organic matter biomarkers as tracers of Hg sources in lake sediments

Lignin biomarkers as tracers of mercury sources in lakes water column

Sources of organic matter and methylmercury in littoral macroinvertebrates: a stable isotope approach

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