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Sa R, Wang Z, Xu Z, Zhao Q, Zhang Q, Zhang X. Distribution characteristics of mercury concentration and estimation of mercury pools in different age groups of Larix gmelinii forests of Daxing'an Mountain. Environ Pollut 2023; 338:122653. [PMID: 37778492 DOI: 10.1016/j.envpol.2023.122653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/03/2023]
Abstract
Forests are important sinks of atmospheric mercury. Quantifying mercury pools in forest ecosystem tissues are essential for understanding the global mercury cycle. To reveal the characteristics of Hg concentration and Hg pool distribution in natural forests at different ages, samples from the vegetation layer, organic horizons, coarse wood debris, and mineral soil layers were collected in young forest, middle forest, near-mature forest, and mature forest of Larix gmelinii forests at the Daxing'an Mountain. The results showed that there were differences in the absorption and accumulation of Hg by different tree species and tissues. In Larix gmelinii, the concentration of Hg followed the order of bark > branch > leaf > root > core, whereas in Betula platyphylla, the order was bark > leaf > branch > root > core. The mercury concentration in the organic horizons increased gradually with the decomposition process. There were no obvious regular patterns in the mercury concentrations of each tissue in different age groups Larix gmelinii forests. Furthermore, total biomass mercury pools (overstory, shrub layer, herb layer, moss layer, and coarse woody debris (CWD)) in the young, middle, near-mature, and mature forests of Larix gmelinii forests at Daxing'an Mountain were estimated to be 99.0 μg m-2,207 μg m-2,207 μg m-2 and 194 μg m-2, respectively. On ecosystem scale, total mercury pools were 16.9 mg m-2 (young), 27.5 mg m-2 (middle), 17.0 mg m-2 (near-mature), and 11.8 mg m-2(mature). The mineral soil mercury pool accounts for 94.0%-98.1% of the total ecosystem mercury pool, and its mercury pool proportion gradually decreased with the increase in forest age. These obtained results are quite valuable for further assessing the role of forest ecosystems in the atmospheric mercury cycle and estimating potential mercury emissions from biomass burning during forest wildfires.
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Affiliation(s)
- Rula Sa
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Inner Mongolia Power (Group) Co., Ltd., Inner Mongolia Power Research Institute Branch, Hohhot, Inner Mongolia Autonomous Region, 010020, China
| | - Zhangwei Wang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Zehua Xu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qingpeng Zhao
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiuliang Zhang
- Inner Mongolia Agricultural University, Hohhot, 010019, China; National Field Scientific Observation and Research Station of Greater Khingan Forest Ecosystem, Inner Mongolia, Genhe, 022350, China
| | - Xiaoshan Zhang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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Yuan W, Wang X, Lin CJ, Song Q, Zhang H, Wu F, Liu N, Lu H, Feng X. Deposition and Re-Emission of Atmospheric Elemental Mercury over the Tropical Forest Floor. Environ Sci Technol 2023; 57:10686-10695. [PMID: 37437160 DOI: 10.1021/acs.est.3c01222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Significant knowledge gaps exist regarding the emission of elemental mercury (Hg0) from the tropical forest floor, which limit our understanding of the Hg mass budget in forest ecosystems. In this study, biogeochemical processes of Hg0 deposition to and evasion from soil in a Chinese tropical rainforest were investigated using Hg stable isotopic techniques. Our results showed a mean air-soil flux as deposition of -4.5 ± 2.1 ng m-2 h-1 in the dry season and as emission of +7.4 ± 1.2 ng m-2 h-1 in the rainy season. Hg re-emission, i.e., soil legacy Hg evasion, induces negative transitions of Δ199Hg and δ202Hg in the evaded Hg0 vapor, while direct atmospheric Hg0 deposition does not exhibit isotopic fractionation. Using an isotopic mass balance model, direct atmospheric Hg0 deposition to soil was estimated to be 48.6 ± 13.0 μg m-2 year-1. Soil Hg0 re-emission was estimated to be 69.5 ± 10.6 μg m-2 year-1, of which 63.0 ± 9.3 μg m-2 year-1 is from surface soil evasion and 6.5 ± 5.0 μg m-2 year-1 from soil pore gas diffusion. Combined with litterfall Hg deposition (∼34 μg m-2 year-1), we estimated a ∼12.6 μg m-2 year-1 net Hg0 sink in the tropical forest. The fast nutrient cycles in the tropical rainforests lead to a strong Hg0 re-emission and therefore a relatively weaker atmospheric Hg0 sink.
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Affiliation(s)
- Wei Yuan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xun Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Qinghai Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China
| | - Hui Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Fei Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nantao Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Huazheng Lu
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Méndez-López M, Eimil-Fraga C, Alonso-Vega F, Rodríguez-Soalleiro R, Álvarez-Rodríguez E, Arias-Estévez M, Nóvoa-Muñoz JC. Variation of Hg concentration and accumulation in the soil of maritime pine plantations along a coast-inland transect in SW Europe. Environ Res 2023; 231:116155. [PMID: 37196692 DOI: 10.1016/j.envres.2023.116155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 04/13/2023] [Accepted: 05/13/2023] [Indexed: 05/19/2023]
Abstract
Climatic conditions have been shown as a major driver of the fate of Hg in forest ecosystems at a global scale, but less is known about climatic effects at shorter scales. This study assesses whether the concentration and pools of Hg in soils collected from seventeen Pinus pinaster stands describing a coastal-inland transect in SW Europe vary along a regional climatic gradient. In each stand, samples of the organic subhorizons (OL, OF + OH) and the mineral soil (up to 40 cm) were collected and some general physico-chemical properties and total Hg (THg) were analyzed. Total Hg was significantly higher in the OF + OH than in the OL subhorizons (98 and 38 μg kg-1, respectively), favored by a greater organic matter humification in the former. In the mineral soil, mean THg values decreased with depth, ranging from 96 μg kg-1 in the 0-5 cm layers to 54 μg kg-1 in the deepest layers (30-40 cm), respectively. The average Hg pool (PHg) was 0.30 mg m-2 in the organic horizons (92% accumulated in the OF + OH subhorizons), and 27.4 mg m-2 in the mineral soil. Changes in climatic factors, mainly precipitation, along the coast-inland transect resulted in a remarkable variation of THg in the OL subhorizons, consistent with their role as the first receiver of atmospheric Hg inputs. The high precipitation rate and the occurrence of fogs in coastal areas characterized by the oceanic influence would explain the higher THg found in the uppermost soil layers of pine stands located close to the coastline. The regional climate is key to the fate of mercury in forest ecosystems by influencing the plant growth and subsequent atmospheric Hg uptake, the atmospheric Hg transference to the soil surface (wet and dry deposition and litterfall) and the dynamics that determine net Hg accumulation in the forest floor.
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Affiliation(s)
- Melissa Méndez-López
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias. As Lagoas S/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental. Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain.
| | - Cristina Eimil-Fraga
- Unidad de Gestión Ambiental y Forestal Sostenible, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela. Rúa Benigno Ledo S/n, 27002, Lugo, Spain
| | - Flora Alonso-Vega
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias. As Lagoas S/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental. Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
| | - Roque Rodríguez-Soalleiro
- Unidad de Gestión Ambiental y Forestal Sostenible, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela. Rúa Benigno Ledo S/n, 27002, Lugo, Spain
| | - Esperanza Álvarez-Rodríguez
- Departamento de Edafología y Química Agrícola, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela, Rúa Benigno Ledo S/n, 27002, Lugo, Spain
| | - Manuel Arias-Estévez
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias. As Lagoas S/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental. Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
| | - Juan Carlos Nóvoa-Muñoz
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias. As Lagoas S/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental. Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
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Méndez-López M, Parente-Sendín A, Calvo-Portela N, Gómez-Armesto A, Eimil-Fraga C, Alonso-Vega F, Arias-Estévez M, Nóvoa-Muñoz JC. Mercury in a birch forest in SW Europe: Deposition flux by litterfall and pools in aboveground tree biomass and soils. Sci Total Environ 2023; 856:158937. [PMID: 36167130 DOI: 10.1016/j.scitotenv.2022.158937] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/15/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
Atmospheric mercury (Hg) is largely assimilated by vegetation and subsequently transferred to the soil by litterfall, which highlights the role of forests as one of the largest global Hg sinks within terrestrial ecosystems. We assessed the pool of Hg in the aboveground biomass (leaves, wood, bark, branches and twigs), the Hg deposition flux through litterfall over two years (by sorting fallen biomass in leaves, twigs, reproductive structures and miscellaneous) and its accumulation in the soil profile in a deciduous forest dominated by Betula alba from SW Europe. The total Hg pool in the aboveground birch biomass was in the range 532-683 mg ha-1, showing the following distribution by plant tissues: well-developed leaves (171 mg ha-1) > twigs (160 mg ha-1) > bark (159 mg ha-1) > bole wood (145 mg ha-1) > fine branches (25 mg ha-1) > thick branches (24 mg ha-1) > newly sprouted leaves (20 mg ha-1). The total Hg deposition fluxes through litterfall were 15.4 and 11.7 μg m-2 yr-1 for the two years studied, with the greatest contribution coming from birch leaves (73 %). In the soil profile, the pool of Hg in the mineral soil (37.0 mg m-2) was an order of magnitude higher than in the organic horizons (1.0 mg m-2), mostly conditioned by parameters such as soil bulk density and thickness, total C and N contents and the presence of certain Al compounds.
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Affiliation(s)
- Melissa Méndez-López
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain.
| | - Andrea Parente-Sendín
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - Noemi Calvo-Portela
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - Antía Gómez-Armesto
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - Cristina Eimil-Fraga
- Unidad de Gestión Ambiental y Forestal Sostenible, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela, Rúa Benigno Ledo s/n, 27002 Lugo, Spain
| | - Flora Alonso-Vega
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - Manuel Arias-Estévez
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - Juan Carlos Nóvoa-Muñoz
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
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Méndez-López M, Gómez-Armesto A, Eimil-Fraga C, Alonso-Vega F, Rodríguez-Soalleiro R, Álvarez-Rodríguez E, Arias-Estévez M, Nóvoa-Muñoz JC. Needle age and precipitation as drivers of Hg accumulation and deposition in coniferous forests from a southwestern European Atlantic region. Environ Res 2022; 215:114223. [PMID: 36063908 DOI: 10.1016/j.envres.2022.114223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/29/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
Vegetation and climate are critical in the biogeochemical cycle of Hg in forest ecosystems. The study assesses the influence of needle age and precipitation on the accumulation of Hg in needle biomass and its deposition by litterfall in thirty-one pine plantations spread throughout two biogeographical regions in SW Europe. Well-developed branches of Pinus pinaster were sampled and pine needles were classified according to 4 age classes (y0, y1, y2, y3). The concentration of total Hg (THg) was analyzed in the samples and Hg content in needle biomass and its deposition by litterfall were estimated. The concentration of total Hg (THg) increased with needle age ranging from 9.1 to 32.7 μg Hg kg-1 in the youngest and oldest needles, respectively. The rate of Hg uptake (HgR) three years after needle sprouting was 10.2 ± 2.3 μg Hg kg-1 yr-1, but it decreased with needle age probably due to a diminution in photosynthetic activity as needles get older. The average total Hg stored in needle biomass (HgWt) ranged from 5.6 to 87.8 mg Hg ha-1, with intermediate needle age classes (y1 and y2) accounting for 70% of the total Hg stored in the whole needle biomass. The average deposition flux of Hg through needle litterfall (HgLt) was 1.5 μg Hg m-2 yr-1, with the y2 and y3 needles contributing most to the total Hg flux. The spatial variation of THg, HgWt and HgLt decreased from coastal pine stands, characterized by an oceanic climate, to inland pine stands, a feature closely related to the dominant precipitation regime in the study area. Climatic conditions and needle age are the main factors affecting Hg accumulation in tree foliage, and should be considered for an accurate assessment of forest Hg pools at a regional scale and their potential consequences in the functioning of terrestrial ecosystems.
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Affiliation(s)
- Melissa Méndez-López
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain.
| | - Antía Gómez-Armesto
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
| | - Cristina Eimil-Fraga
- Unidad de Gestión Ambiental y Forestal Sostenible, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela, Rúa Benigno Ledo s/n, 27002, Lugo, Spain
| | - Flora Alonso-Vega
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
| | - Roque Rodríguez-Soalleiro
- Unidad de Gestión Ambiental y Forestal Sostenible, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela, Rúa Benigno Ledo s/n, 27002, Lugo, Spain
| | - Esperanza Álvarez-Rodríguez
- Departamento de Edafología y Química Agrícola, Escuela Politécnica Superior de Ingeniería, Universidade de Santiago de Compostela, Rúa Benigno Ledo s/n, 27002, Lugo, Spain
| | - Manuel Arias-Estévez
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
| | - Juan Carlos Nóvoa-Muñoz
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004, Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004, Ourense, Spain
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Bardelli F, Rimondi V, Lattanzi P, Rovezzi M, Isaure MP, Giaccherini A, Costagliola P. Pinus nigra bark from a mercury mining district studied with high resolution XANES spectroscopy. Environ Sci Process Impacts 2022; 24:1748-1757. [PMID: 35972271 DOI: 10.1039/d2em00239f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Tree bark near former mercury (Hg) mines and roasting plants is known to have exceptionally high (up to several mg kg-1) Hg concentrations. This study explores the change of Hg speciation with depth (down to 25-30 mm from the outermost surface) in black pine (Pinus nigra) bark by means of high-resolution X-ray absorption near edge structure (HR-XANES) spectroscopy at the Hg LIII-edge. Principal component analysis and linear combination fitting applied to the HR-XANES spectra suggested that in the outermost layer (∼0-2 mm from the surface), roughly 50% of Hg is in the form of nanoparticulate metacinnabar (nano-β-HgS). A progressive increase in Hg-organic species (Hg bound to thiol groups) is found in deeper bark layers, while nano-β-HgS may decrease below the detection limit in the deepest layers. Notably, bark layers did not contain cinnabar (α-HgS), which was found in the nearby soils along with β-HgS (bulk), nor Hg0, which is the main Hg species in the atmosphere surrounding the sampled trees. These observations suggested that nano-β-HgS, at least in part, does not originate from mechanically trapped wind-blown particulates from the surrounding soil, but may be the product of biochemical reactions between gaseous elemental Hg and the bark tissue.
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Affiliation(s)
| | | | | | - Mauro Rovezzi
- Univ. Grenoble Alpes, CNRS, IRD, Irstea, OSUG, FAME, Météo France, Grenoble, France.
| | - Marie-Pierre Isaure
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France.
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Méndez-López M, Gómez-Armesto A, Alonso-Vega F, Pontevedra-Pombal X, Fonseca F, de Figueiredo T, Arias-Estévez M, Nóvoa-Muñoz JC. The role of afforestation species as a driver of Hg accumulation in organic horizons of forest soils from a Mediterranean mountain area in SW Europe. Sci Total Environ 2022; 827:154345. [PMID: 35257764 DOI: 10.1016/j.scitotenv.2022.154345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/10/2022] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
Forest areas are a primary sink of atmospheric mercury (Hg) within terrestrial ecosystems, whereas forest vegetation plays a key role in atmospheric Hg transfer to soil horizons. This study assessed variations in total Hg contents (HgT) and accumulation (HgRes) in the soil organic horizons of a forest area in NE Portugal, where post-wildfire afforestation led to the substitution of the native deciduous species (Quercus pyrenaica) by fast-growing coniferous species (Pseudotsuga menziesii and Pinus nigra). The study also evaluated, for each species, the links between Hg contents and other biophilic elements of soil organic matter (C, N, S) present in organic subhorizons (OL, OF, OH). Mean HgT in the organic horizons of the different tree species follow the sequence: P. nigra (88 μg kg-1) < Q.pyrenaica (101 μg kg-1) <P. menziesii (141 μg kg-1). The highest HgRes for the entire organic horizon was found under P. menziesii (471 μg m-2), followed by P. nigra (253 μg m-2) and Q. pyrenaica (189 μg m-2). Among the organic subhorizons, values of HgT and HgRes follow the sequence OL < OF < OH, which is consistent with the degree of organic matter humification. Indeed, HgT and HgRes correlated significantly with the C/N and C/S ratios for all species and organic subhorizons, suggesting that the quality of organic matter may influence strongly the Hg fate in these forest soils. Soils from P. menziesii plots have shown an HgRes 2.5 times higher than in plots dominated by the native Q. pyrenaica. Hg accumulation in the organic horizons, promoted in the coniferous species, may increase the risk of Hg mobilization due to wildfires and forest management practices. Therefore, forest management plans should select cautiously the tree species for afforestation in order to minimize adverse environmental effects caused by changes in the biogeochemical cycle of contaminants such as Hg.
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Affiliation(s)
- M Méndez-López
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain.
| | - A Gómez-Armesto
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - F Alonso-Vega
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - X Pontevedra-Pombal
- Departamento de Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, Rúa Lope Gómez de Marzoa s/n, 15786 Santiago de Compostela, Spain
| | - F Fonseca
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Sta Apolónia, 5300-253 Bragança, Portugal
| | - T de Figueiredo
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Sta Apolónia, 5300-253 Bragança, Portugal
| | - M Arias-Estévez
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
| | - J C Nóvoa-Muñoz
- Universidade de Vigo, Departamento de Bioloxía Vexetal e Ciencia do Solo, Área de Edafoloxía e Química Agrícola, Facultade de Ciencias, As Lagoas s/n, 32004 Ourense, Spain; Campus da Auga, Universidade de Vigo, Laboratorio de Tecnoloxía e Diagnose Ambiental, Rúa Canella da Costa da Vela 12, 32004 Ourense, Spain
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