Ozone concentrations, flux and potential effect on yield during wheat growth in the Northwest-Shandong Plain of China

Ozone (O-3) concentration and flux (F-o) were measured using the eddy covariance technique over a wheat field in the Northwest-Shandong Plain of China. The O-3-induced wheat yield loss was estimated by utilizing O-3 exposure-response models. The results showed that: (1) During the growing season (7 March to 7 June, 2012), the minimum (16.1 ppbV) and maximum (53.3 ppbV) mean O-3 concentrations occurred at approximately 6:30 and 16:00, respectively. The mean and maximum of all measured O-3 concentrations were 31.3 and 128.4 ppbV, respectively. The variation of O-3 concentration was mainly affected by solar radiation and temperature. (2) The mean diurnal variation of deposition velocity (V-d) can be divided into four phases, and the maximum occurred at noon (12: 00). Averaged V-d during daytime (6:00-18:00) and nighttime (18:00-6:00) were 0.42 and 0.14 cm/sec, respectively. The maximum of measured V-d was about 1.5 cm/sec. The magnitude of V-d was influenced by the wheat growing stage, and its variation was significantly correlated with both global radiation and friction velocity. (3) The maximum mean Fo appeared at 14:00, and the maximum measured F-o was -33.5 nmol/(m(2).sec). Averaged Fo during daytime and nighttime were -6.9 and -1.5 nmol/(m(2).sec), respectively. (4) Using O-3 exposure-response functions obtained from the USA, Europe, and China, the O-3-induced wheat yield reduction in the district was estimated as 12.9% on average (5.5%-23.3%). Large uncertainties were related to the statistical methods and environmental conditions involved in deriving the exposure-response functions. (C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.