Ozone could slash crop yields by 40% - what are the main sources?

Question

A recent study showed that rising ozone levels could cut crop yields by 40% by the year 2100.

http://www.treehugger.com/files/2007/10/ozone_could_slash.php

Apparently human fossil fuel use is causing ozone levels to increase. Is ozone simply another biproduct of combustion? What specifically are the main sources of ozone emissions?

Answer 1

NOx (NO and NO2) and VOCs are the main causes of increased tropospheric ozone i.e. ozone in the lowest 8-16 km of the atmosphere as opposed to the stratosphere where ozone depletion has occurred due to CFC use.

NOx has a variety of sources, some natural some man made. Man made combustion of fossil fuels and biomass accounts for roughly 90% of all emitted NOx. Soils, volcanoes and lighning account for the remainder.

On the other hand, most VOCs are emitted by plants. Oak and other broadleafs emit the influential isoprene, and coniferous trees emit a group of compunds called pinenes. Fossil fuel use does cause the emission of ozone precursors i.e. CO from direct combustion; and, alkanes, aromtics and alkenes from fossil fuel processing and use.

Low level ozone production is a continuing concern both for human health and for crop production because this compund adversely affects both. Low level ozone is estimated to be responsible for millions of dollars of crop damage each year. Ozone is known to impact on human pulmonary function leading to a currently poorly quantified number of excess deaths per year.

We can tackle this problem by improving engine quality, by using catalytic converters, public transport and increased cycle use.

Answer 2

Now I am confused...it wasn't but a few years ago that the tree hugging types told us the depleting ozone layer was going to cause global warming and eventually lead to the death to everything on the planet! What ever, the truth is that one good lightening bolt creates more ozone than anything out there. That fresh air you smell after a good storm is mostly the ozone created by the bolts of lightening.

Answer 3

Ozone is formed in the troposphere when sunlight causes complex photochemistry reactions involving oxides of nitrogen (NOx) and volotile hydrocarbons (VOC) that originates chiefly from gas engines and burning of other fuels. Vegetation is another source of VOCs.