Sediment Coring in the Ross Sea: Geochemistry Edition

We’re down to our last two weeks of research and have already collected over 30 sediment cores! Most of these are gravity cores, reaching up to 2.5 meters long, with some piston cores stretching beyond 3 meters. Once collected, we process each core by taking sediment samples for various analyses. The sediment itself will be used for stable isotope measurements, sediment methane analysis, and radiocarbon dating.

​Porewater — the water between sediment grains — is extracted using syringes and rhizon samplers, which carefully pull porewater out of the sediment. This porewater will be analyzed for sulfate, sulfide, chloride, and nitrate. All analyses, except for isotopic ratios and radiocarbon dating, are performed on board.
We are using three main instruments on the ship: a gas chromatograph, an ion chromatograph, and a spectrophotometer. The gas chromatograph measures methane in sediment; the ion chromatograph measures nitrate, sulfate, and chloride; and the spectrophotometer measures sulfide. Before each run of samples, we carefully prepare standards to ensure accuracy.

All of these measurements will help us better understand the carbon cycle and the presence of methane beneath the seafloor. Today, we’ll begin coring again, and we’re hopeful we’ll recover even longer cores!

Hannah Organ
Texas A&M University- Corpus Christi