Deep-sea sediment Microtox toxicity data analyzed from sediment cores collected aboard multiple research cruises in the northern Gulf of Mexico from 2010-09-16 to 2010-10-23

This dataset contains deep-sea sediment Microtox toxicity data analyzed from sediment cores collected aboard R/V Ryan Chouest (10-07-10-RC, 2010-10-07 to 2010-10-17), R/V Ocean Veritas (09-24-2010_Ocean_Veritas, 2010-09-24 to 2010-10-23) and R/V Gyre (09-14-2010_Gyre, 2010-09-14 to 2010-10-20) cruises in the northern Gulf of Mexico from 2010-09-16 to 2010-10-23. Following the Deepwater Horizon oil spill, a series of cruises was undertaken to determine if oil reached the bottom and if sediment toxicity was occurring. Sampling occurred after the wellhead was capped from September through October 2010. Sediment sampling was performed using OSIL multiple corers at 179 stations at water depths ranging from 16 m to 2767 m. A sediment quality approach was used where chemical contaminants were measured to indicate a dose effect, and in situ bacterial toxicity to indicate a biological effect. Three sediment sub-cores were taken from one multi-corer core using a 10 cc (=10 ml) syringe from the undisturbed surface. The three sub-cores were composited into one 30 cc sediment sample for toxicity analysis. Some sediments were analyzed immediately on shipboard, but other sediments were preserved at 20 ºC and analyzed on-shore. Samples measured on shipboard were held at 4 ºC in the dark. The bacteria preparation is added to bulk sediment samples, mixed thoroughly, and then a dilution series is created, and the samples are exposed for 30 minutes. The bacteria and sediment are pelleted, and fluorescence measurements are taken to determine the concentration that provides an EC50 response. The dataset contains the depth, date, and location of sampling collection stations, effect concentration 50 values, and the total concentration of polycyclic aromatic hydrocarbons (PAHs).