Abstract:

Laboratory analysis of Lander Deployed MIMOSA (MIcrobial Methane Observatory for Seafloor Analysis) samples. MIMOSA experiments use OsmoSamplers to continuously collect long term, in-situ samples. The samplers are connected to PVC chambers (~100mL volume) that are packed with either control mud from the site (referred to as control chamber), or with a mixture of control mud and oil (referred to as oil chamber). Samplers and chambers are placed on benthic landers and remain at the field site from June to October 2013 at GC600. The samplers slowly collect fluids from inside the chambers over this time frame and store the samples in long, thin bore tubing for analysis on shore. Once recovered, the samples were analyzed for sulfate, chloride, and major ion (strontium, lithium, sulfur, sodium, calcium, magnesium, potassium, barium boron, manganese, iron, silica) concentrations every 4-5 days.

Suggested Citation:

Laura Lapham. 2017. Microbial Methane Observatory for Seafloor Analysis (MIMOSA) geochemical data from a natural seep site in the Gulf of Mexico, June to October 2013. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7930R61

Purpose:

To determine rates of sulfate depletion over time when oil is present in chambers. Also to determine concentrations of major ions over time.

Data Parameters and Units:

date (mm/dd/yyyy); Cl (mM); SO4 (mM); date (mm/dd/yyyy); strontium (Sr, umol/kg); lithium (Li, umol/kg); sulfur (S, mmol/kg); sodium (mmol/kg); calcium (Ca, mmol/kg); magnesium (Mg, mmol/kg); potassium (K, mmol/kg); barium (Ba, umol/kg); boron (B, umol/kg); manganese (Mn, umol/kg); iron (Fe, umol/kg); silica (Si, umol/kg). Chambers are ~150mL volume PVC cylinders that have 8um mesh on the top and bottom. Chambers are filled with either control mud (i.e., homogenized sediment from the site of interest) or oil mud (20% volume oil added to control mud and homogenized)

Methods:

The samplers are connected to PVC chambers (~100mL volume) that are packed with either control mud from the site (referred to as control chamber), or with a mixture of control mud and oil (referred to as oil chamber). Samplers and chambers are placed on benthic landers and remain at the field site for several months to a year. The samplers slowly collect fluids from inside the chambers over this time frame and store the samples in long, thin bore tubing for analysis on shore. Sulfate and chloride measured via ion chromatograph and standard methods. Methane concentrations measured via gas chromatography via Magen et al., 2014. Major and trace metals measured via inductively coupled plasma–atomic emission spectroscopy (ICP-AES) via Wheat et al., 2000

Instruments:

Dionex ICS 1000 ion chromatograph SRI mult-gas gas chromatograph ICP-AES

Individual Files: