An inventory of biogenic volatile organic compounds for a subtropical urban-rural complex

Increases in atmospheric volatile organic compounds (VOC), especially in relation to biogenic VOC (BVOC), and haze days that affect the built-up areas are believed to be closely correlated. The present study aims to provide a spatially and temporally resolved BVOC inventory of a subtropical urban-rural complex, the Greater Hangzhou Area (GHA) in China. Urban green space was subdivided into block green space and linear green space; rural areas were classified into four primary forest types. A field survey was conducted to assess the vegetation composition (species, size) and foliar mass of each tree species. BVOC emission potentials were obtained from measurement and literature. Results showed (1) the emission intensity (annual BVOC emissions per land area) in the entire GHA is 3.37 x 10(6) g C km(-2) yr(-1), and rural forest (excluding bamboo forest) exhibits lower average emission intensity (2.74 x 10(6) g C km(-2) yr(-1)) than that of urban green space (3.13 x 10(6) g C km(-2) yr(-1)); (2) Within the built-up area, the block green space has higher emission intensity (3.93 x 10(6) g C km(-2) yr(-1)) than the linear green space (2.63 x 10(6) g C km(-2) yr(-1)); (3) in Hangzhou city, BVOC emissions of native and exotic trees exhibited no differences; and (4) in rural areas, bamboo forests and coniferous forests were the major contributors of BVOC emissions, whereas the original vegetation type of this region, evergreen broad-leaved forest, possessed lower BVOC emissions. The results suggest that total BVOC emission can be controlled to low levels by planting low-emitting species in built-up areas while restoring original broad-leaved forest vegetation in rural areas. (C) 2012 Elsevier Ltd. All rights reserved.