Characterization of Volatile Organic Compound Emissions and CO2 Uptake from Eco-roof Plants.

Vegetation plays an important role in biosphere-atmosphere exchange, including emission of biogenic volatile organic compounds (BVOCs) that influence the formation of secondary pollutants. Gaps exist in our knowledge of BVOC emissions from succulent plants, which are often selected for urban greening on building roofs and walls. In this study, we characterize the CO2 uptake and BVOC emission of eight succulents and one moss using proton transfer reaction - time of flight - mass spectrometry in controlled laboratory experiments. CO2 uptake ranged 0 to 0.16 µmol [g DW (leaf dry weight)]-1 s-1 and net BVOC emission ranges -0.10 to 3.11 µg [g DW]-1 h-1. Specific BVOCs emitted or removed varied across plants studied; methanol was the dominant BVOC emitted, and acetaldehyde had the largest removal. Isoprene and monoterpene emissions of studied plants were generally low compared to other urban trees and shrubs, ranging 0 to 0.092 µg [g DW]-1 h-1 and 0 to 0.44 µg [g DW]-1 h-1, respectively. Calculated ozone formation potentials (OFP) of the succulents and moss range 4×10-7 - 4×10-4 g O3 [g DW]-1 d-1. Results of this study can inform selection of plants used in urban greening. For example, on a per leaf mass basis, Phedimus takesimensis and Crassula ovata have OFP lower than many plants presently classified as low OFP and may be promising candidates for greening in urban areas with ozone exceedances.

Measuring volatile emissions from moss gametophytes: A review of methodologies and new applications.

Mosses inhabit nearly all terrestrial ecosystems and engage in important interactions with nitrogen-fixing microbes, sperm-dispersing arthropods, and other plants. It is hypothesized that these interactions could be mediated by biogenic volatile organic compounds (BVOCs). Moss BVOCs may play fundamental roles in influencing local ecologies, such as biosphere-atmosphere-hydrosphere communications, physiological and evolutionary dynamics, plant-microbe interactions, and gametophyte stress physiology. Further progress in quantifying the composition, magnitude, and variability of moss BVOC emissions, and their response to environmental drivers and metabolic requirements, is limited by methodological and analytical challenges. We review several sampling techniques with various analytical approaches and describe best practices in generating moss gametophyte BVOC measures. We emphasize the importance of characterizing the composition and magnitude of moss BVOC emissions across a variety of species to better inform and stimulate important cross-disciplinary studies. We conclude by highlighting how current methods could be employed, as well as best practices for choosing methodologies.