Atmospheric Ozone and Ultraviolet B Radiation Impact on Sensitive Crops

Over the past decades, annual average background surface ozone concentration [O3] and ultraviolet 'B‘ (UV-B) radiation have been amongst major atmospheric factors that might have overwhelmingly compromised urban agriculture, impacting crops yield negatively. Some estimated global yield losses due to O3, is estimated to be $14 to 26 billion for rice, soybean, corn and wheat combined. (Royal Society, 2008). Understanding of the relationship between ozone, ultraviolet V-B and their impacts on the ecosystem have been explored extensively and remained a challenge that needs more research. Seasonally, there have been recorded variations of daily tropospheric ozone concentration and UVB level on the surface, with some days above threshold limit to sensitive crops, which may impact crop yield. Since the O3 concentration varies with emission of ozone precursors: nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOC), which are common pollutants around urban settings, an increased in the precursors will lead to an increase in tropospheric O3 that will impact sensitive crop yield. Since both atmospheric factors (O3 and UVB) have quite similar impacts on sensitive vegetations, lots of research experiments and studies have focused primarily on individual impact without clearly distinguishing if a pairing impact exist for both factors on sensitive vegetation based on exposure limit. The objective here is to explore the use of real life situation (non-experimental) from field measurements of O3, UVB, corn growth stages, carbon fluxes and micrometeorological parameters and perform statistical analyses to investigate possible correlation between sensitive crop (e.g. Maize) yield and aforementioned atmospheric factors (ozone and UV-B). The research will be looking at micrometeorological data for climatic influences on carbon flux or net ecosystem exchange (NEE), gross primary production (GPP), net primary production (NPP) and ecosystem respiration (Reco) which can be used to interpret crop yield. Based on this approach, it would be clear to identify which parameter is a major contributing factor that is or are sensitive to crop yield loss that is suitable to use for awareness purpose during crop growing season. This will help to reinforce policy making for O3 control in order to minimize the stressors impacts especially during corn growing season. The data of interest collected for this study covers a 10-year period (2006 – 2015). Because, ozone and UV-B impacts can be classified as secondary effect, it will be rational to explore the primary impactors of yield which is drought by first screening the micrometeorology data to first get rid of drought year. Corn sensitivity threshold limit acquired from experiments is used as a baseline for the trend analysis. From experiment, the ozone critical level of damage for corn is 10 ppb, and for UV-B 10 kJ/m2/d. Corn is a typical crop grown at the USDA (United State Department of Agriculture), Beltsville, metropolitan, where the UV-B data is collected and ozone data is collected by MDE (Maryland Department of the Environment) at Beltsville, Maryland, USA.