Air pollution effect of O3 on crop yield in rural India.

Measurement of surface ozone (O(3)) mixing ratio was made from January 2006 to December 2007 in Ahmednagar (19.1°N, 74.8°E, 657 m above sea level), India. The monthly average of daytime maximum of O(3) mixing ratio ranged from 14 to 57 parts per billion by volume (ppbv) with an annual average of about 20 ppbv. The estimated winter wheat and summer crop yield reduction by 10% and 15%, respectively from present O(3) pollution level associated with AOT40 (accumulation exposure of O(3) concentration over a threshold of 40 ppbv) index values 7370-9150 ppbv h in rural areas.

Surface ozone variability over western Maharashtra, India.

We present the simultaneous field measurements of surface ozone (O(3)) made at the five different sites of western Maharashtra, India for the period between 2001 and 2005. Seasonal variation in O(3) shows a pronounced maximum concentration about 40-50 ppbv in the summer and winter season in the urban site and similar concentration of O(3) is also observed in the rural site despite less emission of precursor gases. The increase in O(3) concentration is observed in the sugar factory premises during sugarcane crushing period. Diurnal patterns in O(3) do not show daytime in situ photochemical buildup at high altitude mountain site. The higher O(3) concentration is observed in the morning hours near to the dam than at urban and rural sites. These variations in O(3) indicate that the local pollutants are major contributors to the O(3) concentrations at the urban and rural sites, while regional transport plays a role at high altitude mountains site. Model simulations using a Eulerian photochemical model have also been carried out with the available data. The comparison of model results with observation shows that a diurnal and seasonal pattern is in good agreement.