Glacier sediment plumes in small bays on the Danco Coast, Antarctic Peninsula

Abstract

Glacimarine sedimentary environments provide information about climate and oceanographic evolution in the Antarctic Peninsula. This study focuses on the generation of sediment plumes from glaciers. In February 2013 and 2014, two Chilean Antarctic Institute (INACH) Scientific Expeditions were carried out on board the Chilean Navy vessel Aquiles. Five relatively small bays were visited: Curtiss Bay, Recess Cove, Beaupre Cove, Paradise Harbour/Oscar Cove and Salvesen bay. Hydrography and turbidity profiling was carried out up to 100 m depth using an SBE19 Plus-V2 CTD-T. In general, the results showed sediment plumes at two levels: an upper plume from the surface up to 10 m deep and a deeper plume at 40-100 m. These plumes were identified by higher turbidity concentrations and their association with colder water tongues. The deeper plume tended to remain below the 1027.5 kg m -3 isopycnal and extended~4 km from the glacier, maintaining its shape with a gradually decreasing particle concentration. This longitudinal extension was favoured by ebb tides. The characteristics of the sediment plumes may be influenced by the heat input from water masses. The contribution of the sediments from these small bay systems could play an important role in regional sedimentary processes.

High-concentration sediment plumes, Horseshoe Island, western Antarctic Peninsula

“…However, this trend is reversed on the Danco Coast, with lower turbidity values in the northern bays. As noted by Rodrigo et al (2016Rodrigo et al ( , unpublished data 2021, colder Bransfield or transitional Weddell waters influence the northern Danco Coast. Further south, the influence of warmer transitional Bellingshausen waters coincides with higher turbidity values.…”

“…The variable turbidity concentration in the water column close to the glacier indicates plume interstratification and different sediment sources from the glacier wall, where higher concentrations were close to the sea floor, demonstrating turbid subglacial discharges. In general, average turbidity values were higher than those found on the Danco Coast in the Antarctic Peninsula (~10 vs ~3.0 mg l -1 ) (Rodrigo et al 2016, unpublished data 2021) and higher than those of King George Island (~5.1 mg l -1 ) (Yoo et al 2015). However, for the stations closer to the glacier, the values were considerably higher compared to those of the Chilean Patagonian fjords, for example (maximum value < 5 NTU or 22 mg l -1 ) (Castilla-Hidalgo et al 2018).…”

“…Vertical profiles of temperature, salinity, pressure and turbidity were obtained by hand with a Sea-Bird Electronics (SBE) 19 Plus V2 CTD-T profiler, down to sea floor depth (< 120 m). The turbidity measurements were obtained using an Environmental Characterization Optics (ECO) sensor with nephelometric yurbidity units (NTUs), and the data were transformed for comparison to mg l -1 according to the linear relationship obtained by Rodrigo et al (2016) using the same CTD. Negative and outlier turbidity data were removed manually.…”

“…In the Antarctic Peninsula Region, meltwater or turbid plumes were previously believed to be rare or without an important role in the sedimentary glacimarine environment (e.g. Griffith & Anderson 1989), but recent studies have shown that this is a common phenomenon in subpolar and transition polar climates (Yoo et al 2015, Rodrigo et al 2016). In the current climate change scenario, accelerated glacier retreats and mass losses can produce an increasing input of glacial meltwater into the fjord regions, a situation that is not yet well evaluated in the Antarctic Peninsula.…”

Investigation of Sediment-Rich Glacial Meltwater Plumes Using a High-Resolution Multispectral Sensor Mounted on an Unmanned Aerial Vehicle

“…Lower SSCs cause a linear increase in the turbidity. If the amount of particle matter increases, a non-linear increase in the turbidity is observed [53]. The sensitivity of a single band is decreased with increasing turbidity and becomes less linear [32].…”