Enhanced trace element mobilization by Earth's ice sheets

Area of Science:

• Geochemistry
• Glaciology
• Oceanography

Background:

• Trace elements are vital for biological productivity.
• Subglacial runoff's role in trace element export is poorly understood.
• Ice sheets significantly influence global biogeochemical cycles.

Purpose of the Study:

• Quantify trace element concentrations in subglacial waters from Greenland and Antarctic Ice Sheets.
• Assess the significance of subglacial meltwater as a source of trace elements to the ocean.
• Investigate the impact of ice sheet processes on trace element mobilization and export.

Main Methods:

• Size-fractionated analysis (0.02, 0.22, 0.45 µm) of trace elements in subglacial water.
• Comparison of trace element concentrations with global riverine and open ocean values.
• Flux estimation of trace elements, particularly iron, from Antarctic Ice Sheet to the Southern Ocean.

Main Results:

• Immobile trace element concentrations in subglacial waters far exceed global averages, indicating significant mineral weathering.
• Antarctic Ice Sheet waters show higher trace element concentrations than Greenland Ice Sheet waters.
• Dissolved iron flux from the Antarctic Ice Sheet to the Southern Ocean is an order of magnitude higher than previously estimated.

Conclusions:

• Ice sheets are significant sources of reactive trace elements to the oceans.
• Subglacial processes create geochemically reactive particulates that influence elemental cycles.
• Export of trace elements from melting ice sheets may enhance ocean biological productivity and impact carbon cycling.