Dataset: Hydrocarbons in sediment
Deployment: AT42-05

Alvin pushcores dedicated to hydrocarbon analyses were sectioned to recover the 0-6cm, 6-12, and 12-18cm fractions, or the 0-10, 10-20, and 20-30cm fractions. 7 ml of sediment from each horizon was sampled for methane analysis. The samples were collected at 10 ml serum vials and treated with 2.8 ml of NaOH 1M. The serum vials were sealed with black stoppers and stored inverted at -20 degrees C. The remaining sediment from each horizon (~40ml of sample) was aliquoted into two 50 ml Falcon tubes and was centrifuged at 3000 rpm for 15 minutes to separate porewater from the sediment. After centrifugation, the porewater was filtered through sterile syringe cellulose 0.45micron filters. 20 ml of the porewater was collected into 20 ml serum vials for saturated hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and alkane analysis and stored at 4 degrees C. The sediment cake from each horizon was kept and stored at 4 degrees C for hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and alkane analysis.

The sediment hydrocarbon analyses were done by  Alpha  Analytical, Mansfield,  MA, USA using  1,8270D-SIM(M).