| Summary: | Changes in the cryosphere extent (e.g., glacier, ice sheet, permafrost, and snow) have been speculated to impact (bio) geochemical interactions and element budgets of seawater and pore fluids in Arctic regions. However, this process has rarely been documented in Arctic fjords, which leads to a poor systematic understanding of land-ocean interactions in such a warming-susceptible region. Here, we present the chemical and isotopic (δ18O, δD, δ11B, and 87Sr/86Sr) compositions of seawater and pore fluids fromfive fjords in the Svalbard archipelago. Compared to bottomseawater, the low Cl− concentrations and depleted water isotopic signatures (δ18Oand δD) of surface seawater and pore fluids delineate freshwater discharge originating from precipitation and/or meltwater of the cryosphere (i.e., glacier, snow, and permafrost). In contrast, the high Cl− concentrations with light water isotopic values in pore fluids from Dicksonfjorden indicate a brine probably resulted from submarine permafrost formation during the late Holocene, a timing supported by the numerical simulation of dissolved Cl− concentration. The freshwater is influenced by the local diagenetic processes such as ion exchanges indicated by δ11B signatures as well as interactions with bedrock during fluid migration inferred from pore fluid 87Sr/86Sr ratios. The interactions with bedrock significantly alter the hydrogeochemical properties of pore fluids in each fjord, yielding spatiotemporalvariations. Consequently, land-ocean interactions in combination with the hydrosphere-cryosphere-lithosphere are critical factors for understanding and predicting the hydrology and elemental cycling during global climate change periods in the past, present, and future of the Svalbard archipelago.
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