Methane in coastal sea water, sea ice, and bottom sediments, Beaufort Sea, Alaska

Online link https://geo-nsdi.er.usgs.gov/metadata/open-file/95-70/metadata.faq.html
Description This report summarizes data acquired from 1990 to 1994 for the gas-hydrate portion of the USGS project "Permafrost and gas hydrate as possible sources of methane" of the USGS Global Change and Climate History program. The objective of this project has be
Originators Lorenson, Thomas D. and Kvenvolden, Keith A.
Publication U.S. Geological Survey Open-File Report 95-70

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water sample

(no definition)

Label Definition
Station Identifier for the sample locality, composed as YYMsssR where YY is the last two digits of the year, M is the month (no samples were taken from October through December, thus one digit suffices), sss is the site number, and R (literally) is present to indicate that the site was occupied at an earlier date.
Latitude North latitude of the sample locality.
Longitude Longitude of the sample locality. Negative values are measured westward from the Prime Meridian, positive values are measured eastward from the Prime Meridian.
Date Calendar date when sample was collected, expressed as a FIPS date using the form YYYYMMDD where YYYY signifies the year, MM the month, and DD the day (month and day beginning with 1).
Sample depth (m) Depth in meters at which water was sampled, measured from sea-surface.
Methane (nM) Dissolved methane concentration in the water.
Methane Isotopic Composition (ppt) Carbon isotopic composition (delta-13C) relative to PDB
Methane Specific Oxidation Rate of microbial oxidation of methane. This "specific oxidation rate" is really just the first order rate constant for methane uptake and has the units (1/day) because the oxidation rate (nM/day) is divided by the concentration (nM).
Methane Oxidation Rate (nM/day) The first order rate constant for the microbial oxidation of methane. We measure methane oxidation by first removing (via shaking) most of the methane from the collected samples. We then spike the samples with a known amount of labeled methane which is somewhere near the concentration of methane in the natural sample. We measure the rate of methane oxidation by watching labeled carbon dioxide grow in. Some methane is converted to biomass and we get at this part by filtering and counting the amount of labeled particulate carbon. Once we have these numbers, we calculate what is called the "specific oxidation rate". This is simply the measured rate divided by the concentration of methane in the incubation vials. This "specific oxidation rate" is really just the first order rate constant for methane uptake and has the units (1/day) because the oxidation rate (nM/day) is divided by the concentration (nM). We can then derive what we call the "ambient oxidation rate" by multipling the "specific oxidation rate" by the concentration of methane actually measured in the samples. This obviously only works if first order kinetics are followed but we have found this to be the case in all of the environments we have studied.
Comments Descriptive information about the water samples or the analyses of them.
PO4 Phosphate concentration in water samples.
Si Silica concentration in water sample.
NO3 Nitrate concentration in water samples.
NO2 (no definition)
NH4 Ammonium concentration in water samples.

CTD cast

(no definition)

Label Definition
Temperature In situ water temperature.
Salinity Salinity of the water as determined from the conductivity measurements recorded by the CTD instrument.
Depth Depth of the CTD instrument when temperature and conductivity were recorded. This parameter is derived internally by the CTD instrument by using ambient hydrostatic pressure.
Conductivity Conductivity of water as determined by the CTD instrument.

ice sample

(no definition)

Label Definition
Core interval (cm) The length of the part of the ice core that was analyzed.
Can Wt. gm Weight in grams of the container before placing the sample into it.
Can+sample Wt. gm Weight in grams of the sample with the container.
Sample Wt. gm Difference between variable "Can+sample Wt. gm" and variable "Can Wt. gm".
Headspace Liters (no definition)
Methane ppm Concentration of methane in the ice-core sample, as a proportion of the weight of the sample.
Methane (nM) Concentration of methane in the ice-core sample, in absolute rather than relative terms.
Carbon Isotopic Composition (ppt) Carbon isotopic composition of the methane in the ice- core sample (delta-13C) relative to PDB
Carbon Isotopic Composition (ppt) duplicate same as Carbon Isotopic Composition (ppt)
Description Textual description of the locality.

sediment sample

(no definition)

Label Definition
Top (of sampled interval in core) Distance from top of sediment core to top of the sampled interval.
Bottom (of sampled interval in core) Distance from top of sediment core to bottom of the sampled interval.
Lithology Short description of the sediment.
Methane (uL/L wet sediment) Concentration of methane in the sediment as a proportion of the volume of the wet sediment.