Truhlar_etal_2017_AllFluxPerCapitaData_README.txt Created 10/03/2017 Last updated 10/19/2017 (DOI added to suggested citation) Contact info: Dr. Allison M. Truhlar, amt94@cornell.edu Suggested citation: Truhlar AM, Brooks RA, Nadeau SA, Makarsky ET, Rahm BG, & Walter MT. 2017. Gas emission data from eight New York State septic systems. Available from Cornell University Library's eCommons Repository. https://doi.org/10.7298/X4ZK5DTF Project location: Eight residential locations in Tompkins, Schuyler, and Seneca counties in New York State. Sampling duration: June - August 2014 Project description: Used static chambers to measure greenhouse gas (CH4, CO2, and N2O) emissions from residential septic systems in upstate NY. Three specific areas of the septic system were targeted: the soil over the leach field and sand filter, and the roof vent. Publications: Truhlar AM, Brooks RA, Nadeau SA, Makarsky ET, Rahm BG, & Walter MT (2016) Greenhouse gas emissions from septic systems in New York State. Journal of Environmental Quality. 45:1153-60. DOI: 10.2134/jeq2015.09.0478. Sponsorship: This data was collected as part of a study for the New York State Water Resources Institute and the New York State Department of Environmental Conservation Hudson River Estuary Program, with support from the New York State Environmental Protection Fund, under New York State Department of Environmental Conservation service contract #C006135. A.M. Truhlar was supported for the duration of the study by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144153. Data re-use statement: This dataset is shared under an Attribution 4.0 International (CC BY 4.0) License. It can be shared and adapted, but appropriate credit and a link to the license must be provided. Any changes to the content must be indicated, and not additional restrictions may be applied. For the full text of the license, see: https://creativecommons.org/licenses/by/4.0/legalcode. Truhlar_etal_2017_AllFluxPerCapitaData.csv: Contains seven columns. See detailed descriptions below. Date: Date the sampling campaign was conducted, formatted as YYYYMMDD. Home_number: A unique identifier for each sampling site. Gas: Either methane (CH4), carbon dioxide (CO2), or nitrous oxide (N2O) Treatment: Describes where each gas sample was taken. Possible values include Leach_field, Sand_filter, Control, Roof, and Garage. Leach_field indicates the chamber was installed over the septic system leach field. Sand_filter indicates the chamber was installed over the septic system sand filter. Control indicates the chamber was installed over control lawn, with no buried septic system features. Roof indicates the gas sample was taken from the roof vent. Garage is a unique treatment at Home_number 6, and was used to identify a second roof vent at the site. Chamber: A unique identifier for each replicate measure taken within a Treatment. Lin_flux: The gas flux calculated via linear regression of gas concentration vs time. Units of g/day. Lin_flux_per_capita: The gas flux in g/day/capita. Methods: The following descriptions are adapted from the associated publication (Truhlar et al., 2016). Soil Gas Flux Sampling: Static gas flux chambers were used to measure the flux of CH4, CO2, and N2O from the soil. In brief, each chamber consisted of two parts: (i) a 30-cm opaque, plastic cylindrical collar with a 5-cm-wide gasket (size 12H, Dykema Rubber Band Co.) and (ii) a 13.2-L opaque, plastic removable cover (Paragon Mfg.). At the top of each cover were two rubber septa, one to allow for the insertion of a sampling syringe and one to allow for installation of a pressure equilibration vent tube. The chamber collars were installed in the soil to a depth of 3 to 5 cm. Gas samples were taken from each chamber over a 30-min period immediately following the placement of the cover on the collar. Samples were collected by inserting a 20-mL syringe in the rubber septum at 0, 10, 20, and 30 min. Samples were stored in 10-mL evacuated serum sample bottles until analysis. Vent Gas Flux Sampling: The gas escaping from the roof outlet vent was sampled using a 1-L syringe with a 97-cm length of plastic tubing. The tubing was lowered into the vent, and 200 mL of air was withdrawn and expelled outside the vent to flush the tube. Subsequently, a 500-mL air sample was taken and stored in a 1-L multilayer foil gas-sampling bag (Restek Corp.). Five 15-mL aliquots were withdrawn from the bag and stored in 10-mL evacuated serum sample bottles. At the time of vent sampling, a 39-cm length of PVC pipe (7.6 cm inner diameter) was attached to the top of the roof vent (7.6 cm outer diameter). The pipe was capped, and a hotwire anemometer (VWR) was immediately inserted into a hole (1.3 cm diameter) drilled 8.5 cm above the base of the pipe to measure the escaping air velocity. Gas Analysis: Concentrations of CH4 and N2O were analyzed on a gas chromatograph (Model 6890N GC/ECD, Agilent Technologies Inc.) using a flame ionization detector and an electron capture detector, respectively. Concentrations of CO2 were analyzed on a LI-6200 Portable Photosynthesis System attached to an LI-6250 CO2 Analyzer (LI-COR). Soil gas fluxes were calculated by plotting the concentration of gas versus time. A linear regression line was fit to this data, and the slope was taken as the rate of gas flux. The R2 value of the CO2 regression plot was used as a quality control measure (Peter Groffman, personal communication, January 2016). Eighty-six percent of CO2 linear regressions had an R2 value of 0.7 or above. Vent gas fluxes were calculated by multiplying the gas concentrations by the area of the vent and the measured air velocity. All fluxes were scaled using either the area of the drainage eld, sand filter, or vent, as appropriate, and converted into a mass flux of gas per capita (in g capita-1 d-1) using the ideal gas law and information about the number of residents in each household. Fluxes measured from the control lawn were scaled using an area equivalent to the drainage field or sand filter area in the same yard.