Effects of drought and recovery on soil volatile organic compound fluxes in an experimental rainforest

This data set was obtained during Biosphere 2 - Water and Life Dynamics (B2-WALD) experimental campaign conducted between September 2019 to January 2020 in the tropical rainforest mesocosm of the Biosphere 2, Arizona, USA (DOI: 10.1126/science.abj6789). The rainforest was subjected to a controlled drought period of 65 days followed by a rewetting period. The data includes soil fluxes, soil deposition velocities and ambient concentrations of several volatile organic compounds (VOCs) including isoprene, monoterpenes, methacrolein plus methyl vinyl ketone, C5H8O, acetaldehyde, acetone, butanone, pentanone, methanol, ethanol, dimethyl sulfide, methanethiol, C4H10S, C3H8OS, and methyl nitrite. These data were calculated from VOC concentrations measured from an automated soil flux measuring system using a proton transfer time of flight mass spectrometer (PTR-ToF-MS). The data also includes soil respiration that was measured from automated soil flux measuring system simultaneously to VOC fluxes. This data were collected to assess the impact of prolonged drought period followed by rain and recovery on soil VOC fluxes. Also included are speciated monoterpenes soil flux measurements collected from three manual soil chambers. Periodically isolated samples were taken from the manual soil chambers using sorbent cartridges and analyzed by gas chromatograph - mass spectrometer (GC-MS). These measurements allowed us to identify the monoterpenes exchange by the soil that include: (-)-alpha-pinene, (+)-alpha-pinene, (-)-beta-pinene, (+)-beta-pinene, gamma-terpinene, beta-myrcene, (+)-limonene, (+)-camphene, alpha-terpinene, and terpinolene. The dataset also includes soil emission fluxes of 13C-enriched acetone always measured using the PTR-TOF-MS. 13C-enriched acetone soil emission fluxes were measured after adding to the soil position specific 13C-labeled pyruvate. The 13C-pyruvate labeling experiments were conducted with the aim of identifying the origin of the VOCs emitted by the soil. Also included are the soil temperature, soil moisture (volumetric water content) and soil matric potential measured using two sensors installed at 5 cm depth from the soil surface.