The marine sedimentary environments of Kongsfjorden, Svalbard: an archive of polar environmental change

Abstract

Kongsfjorden, a fjord in north-western Svalbard, is characterized by large environmental gradients driven by meltwater processes along the margins of tidewater glaciers and the inflow of relatively warm Atlantic Water, the main heat source for the European Arctic. These factors make Kongsfjorden a key area to investigate changes in the polar climate-ocean-glacier system and to examine the resulting effects on the marine environment. The aim of this paper is to synthesize knowledge about the marine sedimentary environment in Kongsfjorden since the last deglaciation. Fjords act as natural sedimentary traps, archiving information about past and present environmental conditions and changes. Geological studies of Kongsfjorden have demonstrated a good potential for reconstructing palaeoenvironments and establishing baselines values for the natural climate changes in the Arctic. Palaeoceanographic reconstructions reveal rising water temperatures similar to modern temperatures ca. 12 000 years ago. The extent of warm Atlantic Water entering the fjords influences processes at, and the stability of, the margins of the tidewater glaciers. Enhanced inflow may cause accelerated glacial melting that, in consequence, leads to an increase in the sediment flux from the glacial catchments into the fjord, as observed ca. 12 000 years ago and at present. However, responses of sediment flux to modern environmental changes remain poorly understood, hence long-term and monitoring studies are needed to quantify and model the effects of climate warming on the sedimentary environment of Kongsfjorden.

Biogeochemistry and microbiology of high Arctic marine sediment ecosystems—Case study of Svalbard fjords

“…Often a bimodal grain size distribution is observed, with modes at 2-3 μm and 10-20 μm reflecting sediment settling from meltwater plumes and a Table 1. Information on the four fjords this review is focused on, including length and width, and sizes of local glaciers (Blaszczyk et al 2009; glacier area updated using the GLIMS Glacier Database), glacial coverage (Hagen et al 1993;Svendsen et al 2002), and bedrock composition (Hjelle 1993;Ohta et al 2007Ohta et al , 2008Dallmann 2015 secondary mode at > 100 μm attributed to ice-rafted debris (Kumar et al 2018;Husum et al 2019). The input of freshwater and detrital material at the head of the fjord and the inflow of water from the shelf at its mouth create strong gradients in hydrology, geochemistry, and biology along the longitudinal axis of the fjords (Svendsen et al 2002;Koziorowska et al 2016Koziorowska et al , 2018.…”

“…Kongsfjorden sedimentation rates range from < 0.1 cm yr −1 in the outer fjord (Elverhøi et al 1983) to 12–100 cm yr −1 near the terminus (Kehrl et al 2011; Bourgeois et al 2016). Often a bimodal grain size distribution is observed, with modes at 2–3 μ m and 10–20 μ m reflecting sediment settling from meltwater plumes and a secondary mode at > 100 μ m attributed to ice‐rafted debris (Kumar et al 2018; Husum et al 2019).…”

Microbial Abundance and Enzyme Activity Patterns: Response to Changing Environmental Characteristics along a Transect in Kongsfjorden (Svalbard Islands)

“…Their geographical coordinates are reported in Table 1. Station 4, close to the mooring Dirigibile Italia (MDI), was sampled at six depths (1,5,25,50,75, and 100 m), using different 10-liter Niskin bottles mounted on a single rope, which were closed at the chosen depths.…”

“…During the last decade, these conditions have generated both freshwater and sediment gradients, affecting the whole fjord productivity, carbon sequestration, and overall ecosystem status [24]. Due to its peculiar characteristics, Svalbard fjords can therefore represent natural archives that allow us to reconstruct environmental variability and establish baseline values for the changes occurring in the Arctic Ocean [25]. Moreover, connecting land to ocean, Arctic fjords play an important role in climate change in the overall area [26].…”

Ocean surface warming in Krossfjorden, Svalbard, during the last 60 years

“…2-3 µm and 10-20 µm and a secondary mode at > 100 µm Fig. 1 a Map of the Svalbard region highlighting the study area (rectangle), and major features of ocean surface circulations, North Atlantic Current (NAC: red) and East Spitsbergen Current (ESC: blue) (upper panel), location of Lomonsovfonna Ice core (denoted as a star) [64], b the location of the Krossfjorden core site is denoted as a red circle (lower panel) [64] also known as IRD, which has a limited distribution in Krossfjorden [24].…”