The Effects of Air Pollutants on Vegetation and the Role of Vegetation in Reducing Atmospheric Pollution

Abstract

The main air pollutants are represented by gases forms, particles in suspension, different ionizing radiation and noise. The gases forms are: oxidized and reduced forms of carbon (CO 2 , CO, CH 4 ), of nitrogen (NO 2 , NO, N 2 O 4 , NH 3 , NH 4+ ), SO 2 , O 3 , C 6 H 6 vapours, Hg, volatile phenols, Cl 2 , etc. The particulate forms are: PM10 and PM2.5 particulate matter, heavy metals with toxic effect (Pb, Ni, Cd, As), polycyclic aromatic hydrocarbons PAHs, etc. Atmospheric pollutants have a negative effect on the plants; they can have direct toxic effects, or indirectly by changing soil pH followed by solubilization of toxic salts of metals like aluminum. The particulate matters have a negative mechanical effect. They cover the leaf blade reducing light penetration and blocking the opening of stomata. These impediments influence strongly the process of photosynthesis which rate declines sharply. Also the leaves of the trees have an important role in retention of the particulate matters; they are mostly affected when the wet and dry atmospheric deposition increase. The vegetation plays an important positive role in atmospheric purification and air pollutants reduction. The primary producers represented by plants are an important component in biogeochemical cycles. The vegetation made exchanges with a part of the atmospheric gases by photosynthesis, respiration processes, and the final stage of litter decomposition which mineralization. The plants play an important role in reducing atmospheric CO 2 content, by photosynthesis. This reduction of atmospheric CO 2 content has an important role in reducing of greenhouse gases, participating in reducing greenhouse effect and its consequences on climatic changes. The carbon stored in plants is the result of balance between carbon fixed by photosynthesis and carbon released in the atmosphere by respiration. As the structure of vegetation is more complex, the carbon stock in plants biomass is higher and the period of storage is longer. The most efficient type of vegetation in storing carbon in terms of carbon stored in plants alive is the temperate-continental forest; and in terms of carbon stored in dead organic matter are peat lands.

Living walls in indoor environments

“…Modest concentrations can be a sulphur source. After entering through stomata following the same pathway as CO 2 , it may be utilised in a 'reductive sulphur cycle' to form amino acids needed for growth and development [60].…”

Studying the Impact on Urban Health over the Greater Delta Region in Egypt Due to Aerosol Variability Using Optical Characteristics from Satellite Observations and Ground-Based AERONET Measurements

“…The study [2] found that smoke from the agriculture waste contributed to the urban air pollution as well as from the open fires generated at sunset (when it is less likely to get observed), which is the worst time for Cairo's air quality. Besides, it is reported that Cairo's increased ozone during summer is transported from Europe [82], and the CO increases as a result of the Khamsin events and industrial pollution [14]. A study also showed that the anticyclone flow of the Asian summer monsoon can transport the pollution from Asia toward Africa [83].…”

“…In 2007, the World Bank characterized the air quality in Cairo as the "worst" in the world with regard to particulate matter concentration [13]. Much higher and frequent air pollution episodes were recorded recently in Cairo, threatening the public health of its over 20 million population [3], since human lungs can be severely damaged by the dust, the tiny soot fragments, and pollutant particulates [14]. Besides the emission of air pollutants, naturally, Cairo is at the apex of the Nile Delta that is bounded by the Mokattam Hills and the western heights.…”

Changes in the concentration of pollen over an 11-year period in a Polish urban environment

“…A steady rise in car use, a lack of ring roads, and the presence of a built-up area result in unacceptably high levels of gas and fumes, including . NO 2 may lead to a range of pathological conditions in plant cells, for example damage to the chloroplast membranes and necrosis, which may limit the release of pollen in the tested plants [30].…”