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Description
The submarine groundwater discharge (SGD) has been recently shown to impact geochemical budgets of the ocean as well as seafloor biota. SGD in the Arctic region is regulated by glaciers and permafrost. Expected climate change in the Arctic Ocean and its impact on the ice cover may alter the input of freshwater to SGD and result in so far unknown consequences. Given the absence of holistic investigations, we propose a multi-disciplinary project to investigate SGD around Svalbard and northern Norway where SGD is expected or was confirmed by our tentative work. We propose to conduct detailed surveys to 1) determine the factors controlling SGD; 2) reconstruct SGD history through authigenic precipitates; 3) quantify the fluxes of groundwater and accompanying solutes to the overlying water column; 4) investigate the impact of SGD on benthic meio- & macro-fauna. To achieve these goals, we propose multitask field campaigns to conduct high resolution acoustic and optical seafloor mapping and systematic seafloor sampling for sediment, authigenic precipitates, pore fluid and biological samples with a remotely operated vehicle (ROV). The knowledge gained from the proposed study will provide baseline information on the environmental impact of SGD, which is crucial for predictions in a changing Arctic. The ambitious research program can only be executed by a scientific team that brings together expertise in geology, geochemistry, and biology to examine the different aspects of ecosystem functioning. Publications in high impact journals are expected with future collaborations of research activities and proposals fostered by the current joint efforts.
Summary of project results
The understanding of submarine groundwater discharge (SGD) in high-latitude regions remains significantly limited, with notable gaps in our knowledge about its spatial and temporal extent. This lack of clarity hinders the ability to assess how SGD influences and interacts with glacial dynamics in these areas. The connection between SGD and glacier changes is particularly critical, as it could play a pivotal role in glacial melting and retreat, yet it remains largely unconstrained. Additionally, the ecological impacts of SGD in high-latitude ecosystems are not well understood. This discharge could potentially introduce nutrients or pollutants into these sensitive environments, affecting marine life and biological productivity, but these impacts are still unclear. Moreover, the solute fluxes from SGD to the overlying ocean have not been quantified, leaving a significant gap in our understanding of how this process influences ocean chemistry and nutrient dynamics.
Studying SGD and its ecological impacts in high latitudes is particularly challenging due to the limited ability to obtain samples and visually survey the seafloor under harsh weather conditions. The extreme and often inaccessible nature of these environments makes it difficult for researchers to conduct comprehensive field studies. Additionally, confirming the presence of SGD relies heavily on geochemical analyses, either in the water column or from sediment samples, which are time-consuming and labor-intensive, particularly when attempting to cover large areas. Geochemical and biological analyses require sophisticated analytical capabilities due to the typically small quantities of fluid samples available, further complicating the research efforts. Limited prior research and data availability lengthen the initial stages of project planning and site selection.
Freshening of fluid caused by groundwater discharge in Svalbard sediments was successfully identified, and active SGD was detected in the Lofoten and Vesterålen (LV) regions of northern Norway. Additionally, groundwater within the Gulf of Finland seafloor was observed during the last project cruise. Detailed surveys of SGD activity at three locations were conducted, providing valuable data on the dynamics and extent of groundwater discharge. Sediment cores and samples were collected from various investigated sites, providing material for subsequent geological and geochemical analyses. Pore fluid samples were systematically collected for a range of analyses, contributing to the understanding of subsurface fluid dynamics and chemical composition. Water column and benthos samples were also collected to further study the interactions between SGD and the ecosystem.
To support these scientific achievements, the project webpage was created to disseminate information, updates, and findings to the public, scientific community, and stakeholders. Project meetings were successfully organized, providing a forum for all project investigators to share progress, discuss challenges, and plan future activities. These meetings fostered collaboration and ensured cohesive project execution. Efficient coordination of research vessels and equipment was achieved, optimizing their use for field campaigns and ensuring that all necessary resources were available for data collection and analysis. Continuous supervision and monitoring mechanisms were implemented to track project milestones and deliverables. Regular reviews ensured that the project stayed on track and addressed any issues promptly. A streamlined process for transferring results between different work groups was established, promoting interdisciplinary collaboration and integration of findings. Results were presented at international conferences, workshops, and seminars, ensuring that the scientific community was informed of the project’s progress and findings. Key findings and their significance were communicated to the general public through various outreach activities.
We confirm the spatial extent of submarine groundwater discharge (SGD) from three high-latitude locations: offshore Lofoten archipelago (R/V GOSars, November 2021), Hornsund and Isfjorden in Svalbard (Arex 2021, Arex 2022, R/V Kronprins Haakon March 2023), and the Gulf of Finland. From the dating of seafloor nodules and pore fluids, we have successfully connected the discharge of offshore groundwater with the deglaciation of the Fennoscandian Ice Sheet, thereby establishing the long history of SGD in these areas. This historical linkage provides a deeper understanding of how past glacial movements have influenced present-day groundwater discharge patterns.
The impacts of SGD on the ecosystem have been documented through detailed seafloor observations and precise sampling of sediment and animal samples. Our findings suggest that variations in salinity and solute fluxes play a crucial role in the survival of seafloor animals, affecting their distribution and health.
Solute fluxes to the overlying oceans have been quantified through porewater profiles and water column tracer concentration analyses. Our results indicate that most of the porewater solutes transported by groundwater discharge are rapidly diluted in the water column. This dilution process proves the discharge of offshore groundwater into the overlying oceans, underscoring the subtle yet significant influence of SGD on ocean chemistry.
Preliminary results from Isfjorden suggest that offshore groundwater discharge may provide additional heat to the surface ocean, potentially preventing sea ice formation in the fjord. Results from the Gulf of Finland indicate that SGD may be partly responsible for the formation of manganese-iron nodules on the seafloor and for maintaining seafloor features such as pockmarks in this region.
The ArcticSGD project yields insights mainly for scientists across multiple disciplines, including biologists, geologists, and geochemists. While scientists are the primary beneficiaries of this research, there are also benefits for the general public, particularly residents of regions like Svalbard who are curious about the fjords surrounding them. Places like Murdoch Hole, which are locally famous, become more intriguing as their ecological importance is revealed through scientific research. This knowledge raises a deeper connection between residents and their environment, promoting conservation efforts and sustainable management practices.
Summary of bilateral results
The bilateral cooperation was satisfactory. The members of the two teams jointly prepared four publications and one grant proposal submitted to the Water4All 2023 Joint Transnational Call on 2.04.2024. Thus, they fulfilled the indicators established in the project proposal.