Long-Term (∼57 ka) Controls on Mercury Accumulation in the Souther Hemisphere Reconstructed Using a Peat Record from Pinheiro Mire (Minas Gerais, Brazil)

Pérez-Rodríguez, Marta; Horák‐Terra, Ingrid; Rodríguez‐Lado, Luis; Aboal, J.R.; Cortizas, Antonio Martínez

doi:10.1021/es504826d

“…The main advantage of using component scores rather than the original geochemical data in the regression analysis is that the rotated components represent new synthetic orthogonal variables, and the effects of these components within the regression analysis are additive. The record of the regression weights of the components with depth/time was used to evaluate the chronological variations of the controls on the Hg record [51]. All statistical calculations were performed within the statistic environment of R-version 3.3.3 [52].…”

Section: Statistical Treatmentmentioning

confidence: 99%

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

Schütze

¹

,

Tserendorj

²

,

Pérez-Rodríguez

³

et al. 2018

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Forest vegetation plays a key role in the cycling of mercury (Hg) and organic matter (OM) in terrestrial ecosystems. Litterfall has been indicated as the major transport vector of atmospheric Hg to forest soils, which is eventually transported and stored in the sediments of forest lakes. Hence, it is important to understand how changes in forest vegetation affect Hg in soil and its biogeochemical cycling in lake systems. We investigated the pollen records and the geochemical compositions of sediments from two lakes (Schurmsee and Glaswaldsee) in the Black Forest (Germany) to evaluate whether long-term shifts in forest vegetation induced by climate or land use influenced Hg accumulation in the lakes. We were particularly interested to determine whether coniferous forests were associated with a larger export of Hg to aquatic systems than deciduous forests. Principal components analysis followed by principal component regression enabled us to describe the evolution of the weight of the latent processes determining the accumulation of Hg over time. Our results emphasize that the in-lake uptake of Hg during warm climate periods, soil erosion after deforestation and emissions from mining and other human activities triggered changes in Hg accumulation during the Holocene stronger than the changes caused by forest vegetation alone. and trace element transport in several ways. First, the presence of vegetation stabilizes catchment soils and reduces the transport of particulate materials to surface waters [14]. Second, vegetation has an influence on the amount of litter that is produced, e.g., deciduous trees produce more litter than coniferous trees, which affects the trace element concentrations in the released dissolved organic matter (DOM) [15,16]. Third, vegetation and OM quality affect soil development, e.g., deciduous litter promotes the presence of invertebrates and soil mixing, which results in longer contact times between OM and soil mineral particles [17]. Fourth, differences in plant species compositions affect the interception area, which in turn affects the sequestration of atmospherically deposited trace elements [1,18]. Fifth, litter from different vegetation types decomposes at different rates, depending, e.g., on the litter chemical composition [19,20]. This affects the production of DOM and the amount of trace elements bound to each unit of OM so that more decomposed OM has higher Hg concentrations. Some studies have shown that Hg concentrations are higher in the litter of coniferous forests than deciduous forests [21,22]. In contrast, others studies have demonstrated that Hg concentrations in coniferous litter may be lower than those in deciduous litter [1,23,24], which might be due to varying conditions of atmospheric Hg concentrations or exposure. Jiskra et al.[25] indicated, with Hg isotope analyses in boreal soils, that 90% of Hg in forest soil is deposited by litter. While the vegetation acts as a short-term sink for atmospheric Hg, forest soils can be regarded as long-term sinks [26]. Drenner et a...

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“…The main advantage of using component scores rather than the original geochemical data in the regression analysis is that the rotated components represent new synthetic orthogonal variables, and the effects of these components within the regression analysis are additive. The record of the regression weights of the components with depth/time was used to evaluate the chronological variations of the controls on the Hg record [50]. All statistical calculations were performed within the statistic environment of R -version 3.3.3 [51].…”

Section: Statistical Treatmentmentioning

confidence: 99%

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

Schütze¹,

Tserendorj²,

Pérez-Rodríguez³

et al. 2018

Preprint

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Forest vegetation plays a key role in the cycling of mercury (Hg) and organic matter (OM) in terrestrial ecosystems. Litterfall has been indicated as the major transport vector of atmospheric Hg to forest soils, which is eventually transported and stored in the sediments of forest lakes. Hence, it is important to understand how changes in forest vegetation affect Hg in soil and its biogeochemical cycling in lake systems. We investigated the pollen records and the geochemical compositions of sediments from two lakes (Schurmsee and Glaswaldsee) in the Black Forest (Germany) to evaluate whether long-term shifts in forest vegetation induced by climate or land use influenced Hg accumulation in the lakes. We were particularly interested to determine whether coniferous forests were associated with a larger export of Hg to aquatic systems than deciduous forests. Principal components analysis followed by principal component regression enabled us to describe the evolution of the weight of the latent processes determining the accumulation of Hg over time. Our results emphasize that the in-lake uptake of Hg during warm climate periods, soil erosion after deforestation and emissions from mining and other human activities triggered changes in Hg accumulation during the Holocene stronger than the changes caused by forest vegetation alone.

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“…In this work, we found that three of the four main processes controlling Hg concentration depended on climate: wet and dry Hg deposition (rainfall and dustfall, respectively), as well as local catchment soil erosion owing to precipitation events [29]. The effect of long-term peat decomposition, the only autogenic process identified, was confined to the Holocene section of the peat [29].…”

Section: Introductionmentioning

confidence: 81%

“…In a recent work, we studied Hg accumulation in Pinheiros (18 • S, 43 • W) [29], a Pleistocene age (last~57 ka) tropical mire located in a valley in Serra do Espinhaço Meridional (state of Minas Gerais, Brazil). In this work, we found that three of the four main processes controlling Hg concentration depended on climate: wet and dry Hg deposition (rainfall and dustfall, respectively), as well as local catchment soil erosion owing to precipitation events [29]. The effect of long-term peat decomposition, the only autogenic process identified, was confined to the Holocene section of the peat [29].…”

Section: Introductionmentioning

confidence: 99%

The Role of Climate: 71 ka of Atmospheric Mercury Deposition in the Southern Hemisphere Recorded by Rano Aroi Mire, Easter Island (Chile)

Pérez-Rodríguez

¹

,

Margalef

²

,

Corella

³

et al. 2018

Geosciences

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0

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The study of mercury accumulation in peat cores provides an excellent opportunity to improve the knowledge on mercury cycling and depositional processes at remote locations far from pollution sources. We analyzed mercury concentrations in 150 peat samples from two cores from Rano Aroi (Easter Island, 27° S) and in selected vegetation samples of present-day flora of the island, in order to characterize the mercury cycling for the last ~71 ka BP. The mercury concentrations showed values ranging between 35 and 200 ng g−1, except for a large maxima (~1000 ng g−1) which occurred at the end of the Last Glacial Maximum (LGM, ~20 ka cal BP) in both peat cores. Low temperatures during the LGM would accelerate the atmospheric oxidation of Hg(0) to divalent mercury that, coupled with higher rainfall during this period, most likely resulted in a very efficient surface deposition of atmospheric mercury. Two exceptional short-lived Hg peaks occurred during the Holocene at 8.5 (350 ng g−1) and 4.7 (1000 ng g−1) ka cal BP. These values are higher than those recorded in most peat records belonging to the industrial period, highlighting that natural factors played a significant role in Hg accumulation—sometimes even more so than anthropogenic sources. Our results suggest that wet deposition, linked to atmospheric oxidation, was the main process controlling the short-lived Hg events, both in the mire and in the catchment soils.

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Long-Term (∼57 ka) Controls on Mercury Accumulation in the Souther Hemisphere Reconstructed Using a Peat Record from Pinheiro Mire (Minas Gerais, Brazil)

Cited by 27 publications

References 79 publications

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

The Role of Climate: 71 ka of Atmospheric Mercury Deposition in the Southern Hemisphere Recorded by Rano Aroi Mire, Easter Island (Chile)

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