Biocrops, or crops used to produce fuel also known as biofuel seem to be a great idea. Raise our fuel, instead of digging it up as in the case of fossil fuel, what could go wrong? Unfortunately, a lot – a new study shows that an increase in the cultivation of biocrops may cause a higher ground-level ozone concentration. What does this mean? More deaths due to air quality, and lower yields of food crops.
Pollution: Ground Level Ozone
Ozone is a different molecular form of oxygen, with the formula O3.
Although ozone is very useful in the upper atmosphere as a sun filter, it can be very dangerous if present in the lower atmosphere (i.e. in the air we breathe).
Ground level ozone can be harmful to both humans and the environment. A study for the Clean Air for Europe Programme (CAFE) indicated that O3 causes the death of about 22 000 people in Europe each year. Moreover, it can also cause a reduction in crop yields, and it damages biodiversity.
Ground level ozone is formed by the reaction of nitrogen oxides (NOx, x = 1,2) and Volatile Organic Compounds (VOCs).
NOx or nitrogen oxides, are mainly emitted as a by-product of a combustion process, as a reaction between the oxygen used in the combustion and the nitrogen naturally present in the atmosphere.
VOCs, on the other hand, are mainly of natural origin; in fact, although some are emitted in the atmosphere from industrial plants, the majority of them are released from vegetation.
Isoprene is the most abundant VOC of biogenic origin, as it constitutes about 40% of the vegetation-released VOCs. Its formula is shown in the picture on the side; you can see how two C=C double bonds are present. This makes the molecule very reactive. For both these characteristics, therefore, isoprene is considered one of the key players in ground level ozone production.
Moreover, isoprene degradation in the atmosphere can lead to the formation of other organic molecules. They can subsequently mix with water droplets and form aerosol particles, which can be hazardous for human health.
For these reasons, isoprene concentration in the lower atmosphere is a parameter which needs to be constantly monitored.
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