Urban stress-induced biogenic VOC emissions and SOA-forming potentials in Beijing

Abstract

Abstract. Trees can significantly impact the urban air chemistry by the uptake and emission of reactive biogenic volatile organic compounds (BVOCs), which are involved in ozone and particle formation. Here we present the emission potentials of "constitutive" (cBVOCs) and "stress-induced" BVOCs (sBVOCs) from the dominant broadleaf woody plant species in the megacity of Beijing. Based on the municipal tree census and cuvette BVOC measurements on leaf level, we built an inventory of BVOC emissions, and assessed the potential impact of BVOCs on secondary organic aerosol (SOA) formation in 2005 and 2010, i.e., before and after realizing the large tree-planting program for the 2008 Olympic Games. We found that sBVOCs, such as fatty acid derivatives, benzenoids, and sesquiterpenes, constituted a significant fraction ( ∼ 40 %) of the total annual BVOC emissions, and we estimated that the overall annual BVOC budget may have doubled from ∼ 4.8 × 10 9 g C year −1 in 2005 to ∼ 10.3 × 10 9 g C year −1 in 2010 due to the increase in urban greening, while at the same time the emission of anthropogenic VOCs (AVOCs) decreased by 24 %. Based on the BVOC emission assessment, we estimated the biological impact on SOA mass formation potential in Beijing. Constitutive and stress-induced BVOCs might produce similar amounts of secondary aerosol in Beijing. However, the main contributors of SOA-mass formations originated from anthropogenic sources (> 90 %). This study demonstrates the general importance to include sBVOCs when studying BVOC emissions. Although the main problems regarding air quality in Beijing still originate from anthropogenic activities, the present survey suggests that in urban plantation programs, the selection of low-emitting plant species has some potential beneficial effects on urban air quality.

The Tree Drought Emission MONitor (Tree DEMON), an innovative system for assessing biogenic volatile organic compounds emission from plants

“…For the plant itself BVOC seem to reduce oxidative stress in case of heat waves or high ozone concentrations [10] and other stress induced by the complex abiotic urban environment [11]. …”

Modeling Ecosystem Services for Park Trees: Sensitivity of i-Tree Eco Simulations to Light Exposure and Tree Species Classification

“…Other uncertainties in the emission pattern of plants were found to originate from seasonal changes that depended on the weather conditions of the previous days and weeks [73], which were not considered herein. Additionally, the potential effects of air pollution [74] or drought [75,76], which might increase or decrease emissions, have been neglected. Since emissions are supposed to trigger aerosol production and ozone formation [77], these deficits may need consideration in order to be appropriately used in combination with regional air chemistry and climate models [78].…”

Revelation of Coupling Biogenic with Anthropogenic Isoprene by Highly Time-Resolved Observations

“…The extremely high sensitivity of biogenic isoprene production towards the high temperature zone could be of a concern in urban areas where the land use and climate change have significantly elevated the urban temperature. The urban heating can add additional stress to vegetation to produce excess biogenic VOCs, which further worsens air quality in the presence of ample oxidants such as hydroxyl radicals, ozone and NOx (Ghirardo et al, 2016).…”