Coastal freshening drives acidification state in Greenland fjords
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Greenland's fjords and coastal waters are highly productive and sustain important fisheries. However, retreating glaciers and increasing meltwater are changing fjord circulation and biogeochemistry, which may threaten future productivity. The freshening of Greenland fjords caused by unprecedented melting of the Greenland Ice Sheet may alter carbonate chemistry in coastal waters, influencing CO2 uptake and causing biological consequences from acidification. However, few studies to date explore the current acidification state in Greenland coastal waters. Here we present the first-ever large-scale measurements of carbonate system parameters in 16 Greenlandic fjords and seek to identify the drivers of acidification state in these freshening ecosystems. Aragonite saturation state (Ω), a proxy for ocean acidification, was calculated from dissolved inorganic carbon (DIC) and total alkalinity from fjords along the east and west coast of Greenland spanning 68–75°N. Aragonite saturation was primarily >1 in the surface mixed layer. However, undersaturated—or corrosive––conditions (Ω < 1) were observed on both coasts (west: Ω = 0.28–3.11, east: Ω = 0.70–3.07), albeit at different depths. West Greenland fjords were largely corrosive at depth while undersaturation in East Greenland fjords was only observed in surface waters. This reflects a difference in the coastal boundary conditions and mechanisms driving acidification state. We suggest that advection of Sub Polar Mode Water and accumulation of DIC from organic matter decomposition drive corrosive conditions in the West, while freshwater alkalinity dilution drives acidification in the East. The presence of marine terminating glaciers also impacted local acidification states by influencing fjord circulation: upwelling driven by subglacial discharge brought corrosive bottom waters to shallower depths. Meanwhile, discharge from land terminating glaciers strengthened stratification and diluted alkalinity. Regardless of the drivers in each system, increasing freshwater discharge will likely lower carbonate saturation states and impact biotic and abiotic carbon uptake in the future.
| Originalsprog | Engelsk |
|---|---|
| Artikelnummer | 158962 |
| Tidsskrift | Science of the Total Environment |
| Vol/bind | 855 |
| Antal sider | 11 |
| ISSN | 0048-9697 |
| DOI | |
| Status | Udgivet - 2023 |
Bibliografisk note
Funding Information:
We thank Kitte Gerlich, Anette Rasmussen, Peter van Breugel for the technical support in the lab and Tinna Christensen for artistic help on our conceptual figure. We thank the captains and crews of RV Sanna and HDMS Lauge Koch, as well as Eik Britsch and Egon Frandsen for logistical support. Cruises were funded by Danish Centre for Marine Science (Grants: 2016-05 and 2017-06). H.H. was supported by the U.S. Fulbright Scholar Program, Danish Government Scholarship Programme, & the Gudrun Gytel Fund as part of his Master's scholarships. J.H. was supported by European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 752325 (GrIS-Melt) and under grant agreement no. 727890 (INTAROS). L.M. was funded by research programme VENI with project number 016.Veni.192.150, which is financed by the Dutch Research Council (NWO). This study is a contribution the project FACE-IT (The Future of Arctic Coastal Ecosystems – Identifying Transitions in Fjord Systems and Adjacent Coastal Areas). FACE-IT has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 869154.
Funding Information:
Data relevant to reproduce the results of this study have been made available on Zenodo, an all-purpose open research repository created by Open Access Infrastructure for Research in Europe (OPENAire), a project supported by the European Commission, and by CERN, the European Organization for Nuclear Research. Total alkalinity, dissolved inorganic carbon, and δ 18 O-H 2 O data are available with the following DOI: https://doi.org/10.5281/zenodo.6759882 . Environmental variables recorded by CTD instruments are available for cruises from the West and East coasts respectively at the following DOIs: https://doi.org/10.5281/zenodo.4062024 and https://doi.org/10.5281/zenodo.5572329 .
Funding Information:
We thank Kitte Gerlich, Anette Rasmussen, Peter van Breugel for the technical support in the lab and Tinna Christensen for artistic help on our conceptual figure. We thank the captains and crews of RV Sanna and HDMS Lauge Koch, as well as Eik Britsch and Egon Frandsen for logistical support. Cruises were funded by Danish Centre for Marine Science (Grants: 2016-05 and 2017-06 ). H.H. was supported by the U.S. Fulbright Scholar Program, Danish Government Scholarship Programme, & the Gudrun Gytel Fund as part of his Master's scholarships. J.H. was supported by European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 752325 (GrIS-Melt) and under grant agreement no. 727890 (INTAROS). L.M. was funded by research programme VENI with project number 016.Veni.192.150 , which is financed by the Dutch Research Council ( NWO ). This study is a contribution the project FACE-IT (The Future of Arctic Coastal Ecosystems – Identifying Transitions in Fjord Systems and Adjacent Coastal Areas). FACE-IT has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 869154 .
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