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Linkage between deposition and air-surface exchange of mercury in forest ecosystems: a comparative study between Switzerland and China

English title Linkage between deposition and air-surface exchange of mercury in forest ecosystems: a comparative study between Switzerland and China
Applicant Alewell Christine
Number 170176
Funding scheme Bilateral programmes
Research institution Institut für Umweltgeowissenschaften Universität Basel
Institution of higher education University of Basel - BS
Main discipline Other disciplines of Environmental Sciences
Start/End 01.01.2017 - 31.12.2020
Approved amount 349'999.00
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Keywords (7)

Hg flux measurements; Hg background concentrations; Hg0; Atmosphere - land exchange; Mercury cycling; Hg stable isotopes; Forest ecosystem

Lay Summary (German)

Lead
Christine AlewellXingbing Feng
Lay summary

In China und der Schweiz unterscheiden sich Trends in der atmosphärischen Quecksilber(Hg)deposition. Während die Hg-Depositionsraten in China zunehmen, sind sie in der Schweiz seit den 60er Jahren gesunken. Dieses Projekt ermöglicht es historische Veränderungen der Hg-Deposition zu rekonstruieren und die komplexe Hg-Biogeochemie in bewaldeten Ökosystemen in der Schweiz und in China zu erforschen.

An beiden Standorten wird die Hg-Verteilung im Bodenprofil charakterisiert, um festzustellen in welchen Tiefen sich am meisten Hg befindet. Mit der Isotopenverdünnungstechnik kann der Anteil von austauschbarem Hg in den Böden quantifiziert werden. Wir werden Langzeitmessungen (> 1 Jahr) des gasförmig elementaren Hg (Hg0)-Flusses oberhalb der Baumkronen und direkt über dem Waldboden durchführen.

Mesokosmos-Experimente dienen der Bestimmung des Anteils der Hg0-Emissionen und des lateralen Austrags von Hg aus dem O-Horizont und dem Unterboden. Für beide Waldbodentypen wird der Einfluss verschiedener Umweltfaktoren auf die Hg0-Emission untersucht: Unterschiedliche Niederschlagsmengen, Temperaturen und Intensitäten der solaren Einstrahlung werden simuliert und die Mikrobenaktivität analysiert.

An beiden Standorten wird die Hg-Isotopenzusammensetzung in der Atmosphäre, im Niederschlag, in der Streu, im Boden und im Ausgangsgestein bestimmt. Das ermöglicht wichtige Einblicke in die Geschichte der Hg-Deposition und lässt zu, dass wir Hg-Hotspots entlang des Bodenprofils lokalisieren können. Hg2+-Reduktionsprozessen in dem O-Horizont und dem Unterboden werden ebenfalls untersucht.

Ziel dieser Studie ist es, die Hg Wirkungspfade in den beiden Waldökosystemen in China und der Schweiz zu verstehen und daraus Erkenntnisse für den globalen Hg-Kreislauf herzuleiten. Es bleibt abzuschätzen, ob die weltweiten Bestrebungen Hg-Emissionen in die Umwelt einzuschränken, wirklich zu einer langfristigen Reduktion der Hg-Konzentrationen in Waldböden in Ostasien und auch in Europa führt.

Direct link to Lay Summary Last update: 22.12.2016

Responsible applicant and co-applicants

Employees

Publications

Publication
Sorption kinetics of isotopically labelled divalent mercury (196Hg2+) in soil
Shetaya Waleed H., Huang Jen-How, Osterwalder Stefan, Mestrot Adrien, Bigalke Moritz, Alewell Christine (2019), Sorption kinetics of isotopically labelled divalent mercury (196Hg2+) in soil, in Chemosphere, 221, 193-202.
An isotopic dilution approach for quantifying mercury lability in soils
Shetaya Waleed, Osterwalder Stefan, Bigalke Moritz, Mestrot Adrien, Huang Jen-How, Alewell Christine (2017), An isotopic dilution approach for quantifying mercury lability in soils, in Environmental Science & Technology Letter, 4, 556-561.

Collaboration

Group / person Country
Types of collaboration
Department of Earth Sciences, University of Uppsala, Uppsala Sweden (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
SLF Switzerland (Europe)
- Research Infrastructure
Chinese Academy of Sciences , Institute of Geochemistry China (Asia)
- in-depth/constructive exchanges on approaches, methods or results
Meteorologie, Klimatologie und Fernerkundung, Universität Basel Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
ICOS, Institut für Agrarwissenschaften Switzerland (Europe)
- Research Infrastructure
WSL Switzerland (Europe)
- Research Infrastructure
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umea Sweden (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Agroscope Reckenholz Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
AGU Fall Meeting 2019 Poster The interplay between land-atmosphere exchange and soil dynamics of mercury in a Swiss subalpine forest 09.12.2019 San Francisco, United States of America Alewell Christine; Feng Xinbin; Huang Jen-How; Osterwalder Stefan;
14th International Conference on Mercury as a Global Pollutant Talk given at a conference The interplay between land-atmosphere exchange and soil dynamics of mercury in a Swiss subalpine forest 08.09.2019 Kraków, Poland Alewell Christine; Osterwalder Stefan; Feng Xinbin; Huang Jen-How;
European Geosciences Union General Assembly 2018 Poster Mercury mobility and speciation in Chinese and Swiss forest soils 08.04.2018 Wien, Austria Huang Jen-How; Osterwalder Stefan; Feng Xinbin; Alewell Christine;


Associated projects

Number Title Start Funding scheme
174101 Seasonal impact of vegetation on atmospheric elemental mercury dry deposition 01.01.2018 Ambizione
148458 Evasion of mercury from boreal mires 01.06.2013 Doc.Mobility
113327 Mercury fluxes and reductive processes in the Alps 01.11.2006 Project funding (Div. I-III)

Abstract

Forest ecosystems in China and Switzerland exhibit distinct Hg deposition trends. While there is continuously increased Hg deposition in China, the deposition rate of Hg has been decreased since 1960s in Switzerland. In this study, we propose a collaborative project to investigate Hg biogeochemical behaviour in the remote forested ecosystems in Switzerland and China to understand how different chronologies of Hg deposition impact Hg biogeochemistry in remote forest ecosystems with a specific focus on atmosphere-land exchange of Hg. We will characterise the profile distribution of Hg at both sites to reveal at which horizons the recently and historically deposited Hg tends to accumulate. Using isotope dilution technique, we will quantify the pool of exchangeable Hg in soils. We will perform the first ever research to quantify gaseous elemental mercury (Hg(0), GEM) fluxes above and below the forest canopy utilising REA and dynamic flux chamber at both sites, in addition to mass balance analysis of Hg. This approach will complete our understanding on Hg biogeochemical cycles in the terrestrial environments at Chinese and Swiss sites. Mesocosm systems with litterfall, O layers and subsoils will be carried out to measure Hg reemission and leaching from soils at the Chinese and Swiss sites under manipulated precipitation, temperatures, biological activities and irradiance to examine how environmental factors affect Hg reemission and leaching from litterfall, O layers and subsoils at both sites. We will also measure Hg isotope compositions of Hg in atmospheric Hg, wet precipitation, litterfall, soils and bedrock at both sites to assess Hg sources along the soil profile to gain more insights into historical changes in deposition sources at both Chinese and Swiss sites. In mesocosm systems, the magnitude and direction of Hg isotope change during incubation will be utilised to identify possible Hg reduction pathways in soils and furthermore to elucidate how the pathway of Hg reduction in litterfall, O layers and subsoils. The proposed research will deliver quantitative information on the air-land exchange of Hg in forest ecosystems with distinct Hg deposition fluxes at the two study sites. This information is crucial for better understanding of global cycling of Hg in the environment, and has the potential in understanding how effective the implementation of the Minimata Convention will curb the process of recovery from Hg accumulation not only in China but also in Europe and North America.
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