Gaseous air pollutants: A review on current and future trends of emissions and impact on agriculture

Abstract

Air pollution recieves one of the prime concern in India, primarily due to rapid economic growth, industrialization and urbanization with associated increase in energy demands. Lacks of implementation of environmental regulations are contributing to the bad air quality of most of the Indian cities. Air pollutants produced in any air shed are not completely confined, but at time trespassing all the geographical boundaries, hence donot remain only a problem of urban centres, but spread and affect remote rural areas supporting large productive agricultural land. Air pollutants pose risks on yield of crops depending on the emission pattern, atmospheric transport and leaf uptake and on the plant's biochemical defense capacity. Recent trends have shown decrease in SO 2 emissions, but increase in NO 2 emission due to more number of automobiles. In past few decades, tropospheric O 3 has been identified as a most important air pollutant of rural areas. Air pollutants produce reactive oxygen species (ROS), which adversely affect biochemical processes of plants and reduce their tolerance capacity to other stresses also. Several vital physiological processes such as photosynthetic CO 2 fixation and energy metabolism are also affected negatively by air pollutants. An adverse effect caused by air pollutants depends not only upon its concentration, but also on the duration and combination of air pollutants. The present review deals with present and future trends of major gaseous pollutants emissions and their impact on crop performance.