Only a few studies have assessed the potential for biodegradation of hydrocarbon pollution in ice-covered seawater. Brakstad et al. (Microbial Ecology, 2008) spiked crude oil in sea ice in a field study in Spitsbergen and sampled the microbial community and residual oil over a 3-month period. They observed a changing microbial community and, particularly in the bottom sea-ice, indications for biodegradation. However, to quantify biodegradation rates, a more elaborate experimental setup is required to distinguish biodegradation from diffusion of hydrocarbons (diffusive losses) and transport of oil (physical losses).

The goal of this project is to (1) quantitatively assess in situ biodegradation rates in Arctic seawater and sea ice, (2) assess potential for biodegradation in melted Arctic sea ice under lab conditions, and (3) investigate the associated microbial and algae community.

Methodology:

Marine diesel, enriched with inter tracer 17α(H),21β(H)-hopane, will be immobilised on hydrophobic fluortex fabrics and placed in and below sea ice in February. Four fjords close to Nuuk, which have a long sea ice season (until May), are selected as potential study sites. The fabrics and surrounding sea ice will be recovered after approximately 1, 2, 3 and 4 month. The monitored parameters will include residual hydrocarbons, microbial community, sea ice thickness, temperature, brine volume, chlorophyll a and the nutrients N, P and Fe.

To asses the potential for biodegradation, the mineralization of marine diesel spiked in melted bottom sea ice will be followed up at 0, 4 and 15°C in a lab experiment.

Field site: One of the fjords with sea ice close to Nuuk will be selected (Kanajorsuit, Kanasut, Nipisa or Kobbefjord)

Contact: Leendert Vergeynst

Participants: Lorenz Meire, Tage dalsgaard, Søren Rysgaard, Pia Lassen, Carsten Suhr Jacobsen and Nils Risgaard-Petersen

Link to Isaaffik website