Objectives

The overall objective is to better understand the role of terrestrial Hg pools and processes that govern its exchange with the atmosphere and aquatic compartments. Specific objectives are the following: (1) to study the mobility of Hg in thawed permafrost (ESR8), (2) to investigate the role of canopy in terrestrial Hg pools inter-compartmental exchanges (ESR9), and (3) to integrate new knowledge into terrestrial modul as part of the multimedia modelling in WP5 and 6.

Description of Work

Mechanisms that drive biogeochemical cycling of terrestrial Hg and dynamics of interactions at land-atmosphere-ocean interfaces will be investigated using a combination of approaches: in-situ (field) measurements in Mediterranean, Atlantic, Baltic coastal sites (in collaboration with WP1, 2), application of newly developed analytical techniques under laboratory conditions (WP2, 4) and modelling (WP5, 6).

Task 3.1 ESR8 will address the reactivity and mobility of Hg in thawing permafrost. Specifically, speciation, reduction/evaporation, desorption kinetics and potential methylation rates of Hg will be examined in frozen-to-thawing permafrost transects available in Northern Sweden through the Swedish Research Polar Secretariat. This will be used as input data in modelling (WP5, 6).

Task 3.2 ESR9 will study the controls of terrestrial Hg pool (partitioning, retention within watersheds and interaction with organic carbon cycle) with the focus on the role of canopy and exchanges of mercury with the atmosphere and aquatic compartments. Secondments to Harvard and HZG will facilitate the quantification of the magnitudes of these inter-compartmental exchanges using their modelling tools. ESR9 will also work closely with ESR7 and 8 at SU to understand the role of DOM on Hg reactivity and mobility in land-to coast and permafrost experimental sites.

Expected Results

ESR8

Process based understanding of mobility and intercompartmental transformation processes of Hg stored in thawing permafrost (2 papers).

ESR9

Improved understanding of the role of canopy as part of the terrestrial Hg pool and in the global biogeochemical cycle of Hg. Integration of new knowledge on controls and magnitudes of its exchange with atmospheric and aquatic ecosystems into a coupled global multimedia model developed in WP 5 (3 papers).

Deliverables

Del. Deliverable Title – Science deliverables WP Lead Type Diss. Due
D3.1. ESR8: 2 papers on (i) the mobility of Hg from thawing permafrost and (ii) methylation of Hg in thawing permafrost. 3, 2, 5 SU PDE PU M42, 46
D3.2 ESR9: 3 papers i) the role of canopy within terrestrial Hg pools uing stable Hg isotopes in field studies (ii) Hg in litterfall and its interactions with the organic matter, and (iii) incorporation and upscaling of the results in regional and global models; joint publication with WP5, 6. 3, 1, 5, 6 JSI PDE PU M24, 36, 46
D15 PhD diplomas for 15 ESRs 1-6 All PDE PU M48

Milestones

No Title WP(s) Lead Benef. Due Date Means of Verification
2 Validated Hg speciation method in seawater 2 AMU M10 Interlaboratory comparison: AMU; CNRS; UPPA; JSI; IFREMER (ESR4)
8 MMHg selective and coupled biomolecules with nanomaterials tested (lab and field) 4, 3 IOS M24 Material tested and cross-validated in collaboration with JSI
9 DOM: desorption kinetics and refractory concentrations of Hg 3, 6 SU M24 Data verified and reported
12? New cruises and data on marine Hg speciation 2, 5 AMU M36 Cruises completed, data verified
13? New data on coastal Hg speciation 2, 5 UPPA M30 Measurements completed and validated
14 Speciation and transformation rates in permafrost 3 US M24 Data validated and reported
20 Compilation of spatially-resolved terrestrial databases completed 3, 5 JSI M26 Data available at AMAP, UNEP, CNR-IIA, HZG. GEO
24 PhD thesis submitted 1-6 all M48 PhD thesis approved by (co)supervisors