Author: @madridbg, through Power Point 2010, using public domain images.
Welcome dear readers of the #hive platform, this publication is intended to address the effect of tropospheric ozone on vegetation, evaluating the benefits or detriments that this chemical molecule, so important for the development of life, causes at the vegetative level, when concentrations exceed the limits established by natural systems.
As has been a constant in my publications, we will share this type of topics through the @ecotrain community, who have remained at the forefront and updated on issues concerning environmental protection and care.
The balance of planetary systems has been somehow affected by the routine development of man. In our eagerness to improve the quality of life, we have exploited the planet's resources without taking timely and corrective measures to mitigate the effects we have generated on our environment.
One of the most marked effects of industrial processes is represented by air pollution due to uncontrolled emissions of polluting gases such as carbon dioxide, nitrogen monoxide, sulfur dioxide, among others. These, together with environmental gases, have generated what is known today as the greenhouse effect. A phenomenon that threatens the well-being of life on the planet.
Fig. 2. Polluting gases are the precursors of tropospheric ozone. Author: PIXNIO
Therefore, in this issue, we will focus our attention on the influence generated by the high concentrations of ozone at tropospheric level, which is considered today as one of the main pollutants in industrialized cities, due to its abundant distribution and the damage it causes to living systems, be they people, plants, animals or any living species.
The objective of this publication is to establish clear criteria that allow predicting which are the damages or manifestations of plants in the presence of this substance known as ozone.
GENERAL INFORMATION ABOUT OZONE
As mentioned in previous publications, ozone is a highly reactive colorless gas, which is part of the defense of our planet, it can be found at the troposphere level and in greater proportion at the stratospheric level, whose concentration exceeds 90% of the concentration of this gas. It is responsible for filtering solar radiation, through the so called ozone layer, which highly energetic ultraviolet radiation with wavelengths below 300 nanometers, are repelled so that when reaching the surface of the earth the energy contained is minimal and does not cause damage to planetary systems and therefore does not affect life on the planet.
Chemically the substance consists of three atoms of oxygen (O3), which is naturally occurring in the troposphere and is synthesized through photochemical reactions and small parts of it, which travels from the atmosphere to the lower layers of the planet. Gases such as carbon monoxide, carbon dioxide and sunlight are the main precursors of tropospheric ozone.
Fig. 3. Chemical representation of the ozone molecule Author: Ben Mills
BEHAVIOR OF PLANTS IN THE PRESENCE OF TROPOSPHERIC OZONE
The presence of chemical substances such as ozone in high concentrations produce damage in many cases irreparable in plants, this due to their physico-chemical properties that present the polluting substances, in this particular, as ozone is a gaseous substance the correlation with plants is carried out through the respiratory absorption pathways, also known as stomata, which are small pores responsible for the exchange of gases from the outside to the inside of the plant, where the necessary variables are obtained to develop the process of photosynthesis and respiration of the same.
Once reached the interior of the plant, the substance has the capacity to enter the plant tissues through the process of passive diffusion and the damage is a function of the concentration of the chemical substance outside the natural process.
Although the functioning of the stomata is regulated by environmental factors such as humidity, light intensity, carbon dioxide concentrations, among others, internally there are also specialized mechanisms that can control the partial closure of the pores, so that in the presence of a pollutant such as ozone, the stomata close and the plants stop receiving a large part of the nutrients necessary for their metabolic functioning.
Fig. 4. Representation of the behavior of stomata in plant leaves. Author: H McKenna
Similarly, it is necessary to make clear that plants have their own defense mechanism and in the presence of harmful substances are activated in order to counteract the damage generated, where the effectiveness of this mechanism depends on the species of the plant, its nutritional status, as well as the age and development of the same.
In this sense and according to the above, we can differentiate the type of exposure to ozone and classify it in those whose concentrations are high but the periods of time associated with it are short, the same we will call water exposure, where the damage observed at the level of the plants are presented in the leaf systems and directly affects the growth of the same.
On the other hand, the chronic exposure is carried out by low concentrations and prolonged time, it does not present visible changes in plants, however, as it has occurred variants in the metabolism of the plant, the productivity of the same is reduced by 50%.
CROP ZONES AND THEIR EFFECTS IN THE PRESENCE OF TROPOSPHERIC OZONE
As mentioned in the previous section, depending on the type of exposure to ozone are the harmful effects on the plant, now what happens if we extrapolate these conditions to crop areas where farmers must manage to get better fruits every year to meet the demands of a society in constant evolution and growth.
In this sense, the task is not easy if we start from the premise that ozone as a pollutant decreases the productivity and growth of plants, so that at the crop level it is more difficult to evaluate each plant separately, we are left only with the observation as a determining mechanism of the present affections.
Fig. 5. Plant species polluted by ozone, exhibit foliar affections. Author: pxhere
In this regard, crops can show visible symptoms in the leaves, such as discoloration, aging, in addition to low productivity and growth, which generates considerable economic losses, beyond the poor quality of the fruit obtained, where values are reported that show a reduction of 14% in the levels of sugars in the fruit, in addition to generating changes in the protein composition of the same. As if this were not enough, the seed germination rate decreases and the flowering period is delayed, all these aspects cause general damage to the crop and consequently substantial losses for the producer.
Through the thematic, we were able to approach the differences between ozone at atmospheric level and its incidence at tropospheric level, where we were able to observe that at high concentrations of ozone the damages are marked for plant species. In this sense, a decrease in greenhouse effect pollutants would be directly proportional to the decrease of ozone in the lower layers of the earth.
 Bermejo, V y Col. Tropospheric ozone and its effects on vegetation. Ministry of the Environment and Rural and Marine Affairs (MARM) and the Center for Research, Energy, Environment and Technology (CIEMAT).. Article: Online Access
 CEO.ORG. The North American mosaic: an overview of the most relevant environmental problems. Article: Online Access
 Bedmar Francisco. School of Agricultural Sciences. National University of Mar del Plata. Special report on agricultural pesticides. Article: Online Access
 Ome Barrera, Ó.; Zafra Mejía, C. (2018). Key factors in bioremediation processes for wastewater treatment. A review. Magazine U.D.C.A Actualidad & Divulgación Científica under a Creative Commons CC BY-NC 4.0 license. Article: Online Access