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Spatial fingerprinting of biogenic and anthropogenic volatile organic compounds in an arid unsaturated zone

October 1, 2019

Subsurface volatile organic compounds (VOCs) can pose risks to human and environmental health and mediate biological processes. VOCs have both anthropogenic and biogenic origins, but the relative importance of these sources has not been explored in subsurface environments. This study synthesizes 17 years of VOC data from the Amargosa Desert Research Site (ADRS) with the goal of improving understanding of spatial and temporal variations that distinguish sources of VOCs from a landfill and surrounding ambient sources including biogenic VOCs (bVOCs). Gas samples were collected from 1999 to 2016 from an array of shallow sample points (0.5 m and 1.5 m depth) and from vertical profiles at three deep boreholes, two (109 m deep) near the border of a waste facility (33 and 100 m distant), and one (29 m deep) in a remote area 3 km to the south. Samples were analyzed for target VOCs and a subset was analyzed for non-target VOCs to enumerate a greater variety of potential bVOCs. Principal components analysis of the target and non-target VOCs provided an assessment of spatial variability of VOCs originating from the landfill site and from ambient sources. Ambient VOCs occurred at all sample sites over a range of depths and most were consistent with biogenic origins, indicating, for the first time, presence of bVOCs in the deep unsaturated zone. Because some VOCs have both anthropogenic and biogenic sources, discrimination of sources can be important for estimating the extent and migration of anthropogenic plumes in arid unsaturated zones.

Citation Information

Publication Year 2019
Title Spatial fingerprinting of biogenic and anthropogenic volatile organic compounds in an arid unsaturated zone
DOI 10.2136/vzj2019.05.0047
Authors Christopher Green, Wentai Luo, Christopher H. Conaway, Karl B. Haase, Ronald J. Baker, Brian J. Andraski
Publication Type Article
Publication Subtype Journal Article
Series Title Vadose Zone Journal
Series Number
Index ID 70209090
Record Source USGS Publications Warehouse
USGS Organization WMA - Integrated Modeling and Prediction Division