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Redefining the role of wetlands as methyl mercury sources

insights from wetlands before and after restoration

Tjerngren, Ida M J (2012). Redefining the role of wetlands as methyl mercury sources. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2012:3
ISBN 978-91-576-7687-0
[Doctoral thesis]

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Current literature identifies boreal wetlands as net sources for the potent neurotoxin methyl mercury (MeHg). Combined with national environmental aims of restoration of previously drained wetlands, there is a possible conflict between the ecological benefits of wetlands and their role as MeHg sources.
This thesis presents a four-year study of seven Swedish boreal wetlands of different nutrient status subjected to restoration measures. Wetlands were characterized according to climate/geography, vegetation type and ancillary chemistry. Mercury (Hg) biogeochemistry was assessed by determination of proxies for long- and short-term net MeHg production rates in soils, i.e., %MeHg (of total Hg) and potential methylation and demethylation rate constants (km and kd). MeHg exports from each wetland catchment were calculated. In addition, each wetland was assessed as a net MeHg source or sink, based on mass balance budgets.
Results follow similar patterns for %MeHg, km/kd and budgets among the wetlands. The nutrient status of the wetlands affect the net production of MeHg, with wetlands of intermediate nutrient status, i.e., poor-fen types of wetlands, having the highest %MeHg, km/kd and the largest net output of MeHg. MeHg budget results showed that six out of seven wetlands were net MeHg sources. The MeHg output varied more among wetlands, than before and after restoration measures of an individual wetland. This suggests that the nutrient status of a wetland is more important to the MeHg production than the performed restoration measures. A nutrient-rich Alnus glutinosa swamp was a net sink for MeHg during the entire study period. A spatial analysis along a gradient into the Alnus swamp showed an increased degradation of MeHg in the swamp soil. Snapshot budgets from nine additional swamps suggest that net degradation of MeHg is a general phenomenon for Alnus swamps.
Results from this thesis have implications for forest managers and landscape planners. Previously drained wetlands can be restored based on informed decisions, avoiding restoration of poor-fen types of wetlands. In addition, Alnus swamps should be maintained and restored if possible, helping to mitigate the production of MeHg in boreal landscapes.

Authors/Creators:Tjerngren, Ida M J
Title:Redefining the role of wetlands as methyl mercury sources
Subtitle:insights from wetlands before and after restoration
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2012
Number of Pages:59
Paper IPotential Hg methylation and MeHg demethylation rates related to the nutrinet status of different boreal wetlands. Tjerngren, I., Karlsson, T., Björn, E., Skyllberg, U. Biogeochemistry (2011)
Paper IIBoreal wetlands as sources and sinks for methyl mercury before and after small-scale flooding. Tjerngren, I., Meili, M., Björn, E., Skyllberg, U. In review in Environmental Science & Technology.
Paper IIINet degradation of metyhl mercury in alder swamps. Kronberg, R-M., Tjerngren, I., Drott, A., Björn, E., Skyllberg, U. Submitted manuscript.
Place of Publication:Umeå
Publisher:Institutionen för skogens ekologi och skötsel, Sveriges lantbruksuniversitet
ISBN for printed version:978-91-576-7687-0
Publication Type:Doctoral thesis
Full Text Status:Public
Subjects:Obsolete subject words > FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING > Soil science
Obsolete subject words > INTERDISCIPLINARY RESEARCH AREAS > Water in nature and society
(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Analytical Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geochemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Oceanography, Hydrology, Water Resources
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Other Earth and Related Environmental Sciences
Agrovoc terms:wetlands, mercury, methylation, alnus, swamps, wetland soils, peatlands, runoff, budgets
Keywords:Mercury, Methyl mercury, Methylmercury, Wetlands, Methylation , Demethylation, Budgets, Restoration, Temperate, Alder, Wetland restoration
Permanent URL:
ID Code:8554
Department:(S) > Dept. of Forest Ecology and Management
External funders:FORMAS and Kempe Foundations and Stiftelsen Oscar och Lili Lamms minne
Deposited By: Ida M J Tjerngren
Deposited On:23 Jan 2012 13:27
Metadata Last Modified:02 Dec 2014 10:48
Project info:
Name:Bildning av metylkvicksilver vid restaurering av skogliga våtmarker - risker och möjliga åtgärder

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