WP1 New observations (NTNU lead, NIVA, MSUG, LMSU)

Objectives: i) Determine bio-essential (Fe, Mn, Zn, Co), toxic (Hg, Pb, As) and potentially toxic (Cd, Ni) trace elements, their distribution in surface sediment and water column with special focus on Fe and Hg; ii) Assess the Fe/N/P/Si supply ratios to the Arctic coastal and ocean waters to assess PfT related changes in macro-micro nutrient stoichiometry on primary production; iii) Determine Hg cycling based on projections, chemical analyses and databases in terms of food web dynamics and biomagnification, and conduct risk assessment of mammal, fish and human Hg exposure; iv) Determine the labile and refractory OM (both terrestrial and marine) for assessing the interactions of bio-essential (Fe) and toxic elements (Hg) with OM and effects on speciation, distribution and mobility/transportation of these elements.

Description: WP1 will perform field expedition studies in the Laptev and North Siberian seas, regions highly impacted by coastal and subsea permafrost degradation, during September-October 2021 or 2022 onboard RV "Akademik Mstislav Keldysh". These cruises are organized in the frame of the International Siberian Shelf Studies (https://tpu.ru/en/research/research_at_tpu/research_priority_areas/arctic_research) program led by Prof. Semiletov and Prof. Shakhova and financed by the Russian Ministry of Sciences and High Education and the Russian Scientific Foundation. Expenses connected with accommodation on the ship and ship time will be covered by the Russian side. These 35 days cruises will start and end in Archahgelsk. Sampling will be performed using Go-Flo Water Samplers, sediments cores, a benthic lander and other available equipment. Besides this WP1 will perform field studies to the main Siberian rivers (N.Dvina, Ob’, Enisey, Lena, Kolyma) in the frames of ongoing students expeditions organized by LMSU, where there will be organized sampling from the river water and river bed.

T1.1 Fe speciation (NTNU/3, NIVA/1, LMSU/1): Determination of concentration and speciation of Fe and other micro nutrients (Mn, Zn, Co, Ni, and Cd) will be done by: a) solid state column pre-concentration techniques using the SeaFast® system and final analysis by ICP-MS (Ardelan et al 2010; Ndungu et al. 2003), b) Flow-Injection Analysis with Chemiluminescence, FIA-CL (Croot et al. 2008; Breitbarth et al. 2010). Analytical quality control will be done with GEOTRACES intercalibration seawater standards.

T1.2 Hg speciation (NTNU/2, NIVA/2, MSUG/1, LMSU/1, SU/1): Total Hg (THg) concentration in water will be measured using automated Brooks Rand THg analysis system. Methylmercury will be analyzed using isotope dilution GC- ICP-MS, after appropriate sample pretreatment procedures (Munson et al. 2014, Soerensen et al. 2016). We will quantify the influx and transformation of Hg species, in Arctic waters at the study sites with documented variable degrees of PfT. We will measure different Hg species in water, sediment, phyto- and zooplankton, benthic organisms. This will allow us to determine changes in the mass balance of Hg, and its species, from the litho- to biosphere. In the end, the results of field studies and experiments will provide empirical and model output that will advance the assessment of societal (culture), economic (local food sources and export market) and human health impacts due to PfT.

T1.3 Dissolved Organic Matter (NTNU/3, MSUG/1, LMSU/1, SU/1): Colored dissolved organic-matter (CDOM) will be measured with Liquid Waveguide Capillary Cells (LWCC) for ultra violet (UV) and visible (VIS) spectroscopy. DOM concentration will be measured by the high-temperature combustion method on a Shimadzu TOC-5000 analyzer. For characterization and molecular details of DOM, Synapt G2-S" Q-TOF instrument from Waters, located in NTNU Chemistry department, the molecular details obtained can be utilized to identify compositional differences among pools of DOM and thus allows for novel insights on the character and origin of DOM. By measuring the fluorescence of DOM (Stedmon et al., 2011) we will be able to assess the source of DOM, and its influence on Fe speciation and bacterial activity.

T.1.4. Cruise workshop (All): The cruise workshop will be organized after the cruise aiming discuss the results obtained and plans of the work on data received

Deliverables: D1.1 Report on the main cruise results. D1.2 2-3 manuscripts on cruise results.

Milestones: M1.1 Accomplishment of the cruise. M1.2 Accomplishment cruise workshop. M1.3 Accomplishment of Siberian Rivers field work studies.

Parameters for selected stations (12+?)

Hydrochemistry:

•The same as for standard stations (see below)

•Chlorophyll

DOC chemistry (LMSU)

•TOC

•SPE/PPL filtration

•Optical measurement (fluorecence and UV)

Metals from go-flo (Murat)

•bioessintial and toxic elements trace metals

•THg+

•MeHg

Microbiology (Winogradslii Inst. of Microbiology)

•14C-primary production

•14C-dark CO2 – assimilation (total microbial activity)

•Total microbial number (DAPI count)

•Taxonomic diversity of microorganisms using analysis of 16S rRNA gene

•14C-CН4 oxidation

•Metagenomic analysis for detection of specific groups of microorganisms

•(methanotrophs, ammonium oxidizing bacteria and archaea, et al)

Parameters for sediments/pore water:

Hydrochemistry:

•O2/рН-optode

•pH-NBS/pH-Tot-spec

•Alk potentiometric titration

•PO4, SI, NO3, NO2, NH4

•Total N,P

•Mn_total dissolved

•Fe total dissolved

•H2S

Microbiology

•14C-dark CO2 – assimilation (total microbial activity)

•14C-CH4 – oxidation

•35S-sulfate reduction

•Taxonomic diversity of microorganisms using analysis of 16S rRNA gene and for selected stations

•metagenomic analysis for detection of specific groups of microorganisms (Bacteria, Archaea Heterotrophs, SOB, SRB, MO, MG, ANME archaea)

DOC

•DOC in pore water?

Metals

•TotHg

•MeHg

•Pore water 0.5 ml?

Parameters for standard stations (12+?)

Hydrochemistry

•O2 Winkler

•O2/рН-optode

•pH-NBS/pH-Tot-spec

•Alk potentiometric titration

•PO4,

•SI,

•NO3,

•NO2

•NH4

•Total N

•Total P

Microbiology

•14C-primary production

•14C-dark CO2 – assimilation (total microbial activity)

•Total microbial number (DAPI count)

•Taxonomic diversity of microorganisms using analysis of 16S rRNA gene