Impact of Air pollution on plants
G.S.Singh* and S.Chattopadhyay **
Central Tasar Research & Training Institute,
Nagri,Ranchi,Jharkhand
**Department of Forest Science, Birsa Agricultural University,
Kanke, Ranchi – 834006
*E-Mail:Jayaraj625@yahoomail.
Air pollutants pollution can be defined as the presence in the atmosphere of substance or substances added directly or indirectly by an act of man, in such amounts as to affect humans, animals vegetation or materials adversely. Plants are very suitable for detecting, monitoring and mitigating air pollution effects. Air pollutants interact with plants and alter their normal functioning.
People have made many changes the world the live in and some of these have had harmful consequences. As the word population increase, there is more need for bigger cities, new town and farming land .Land has to be cleared, destroying the habitats many animals and plants. Some of these are now extinct other are in danger .Hunting has also has put animals in danger.
Industrialization is major threat to the environment. Pollution is just one example. Factories discharge harmful chemical into rivers and seas, killing fish and plants.
The production of chlorofluorocarbons (CFCs) is reckoned to be responsible for damaging the ozone layer ,the protective layer , in the earth’s atmosphere that prevents harmful rays from the sun reaching the surface.CFCs are synthetic chemicals used in aerosol sprays and refrigerators. When they are released in atmosphere, they destroy the ozone. There is now whole in the ozone layer above Antarctica.
Air pollution is caused by fumes and smoke from vehicles, factory chimneys and power station .Poisonous gases, such as Sulphur dioxide, mix with rain and mist to produce acids. When the acid rain falls, it kills plants over a wide area. Burning fuels also causes a build-up of carbon dioxide.
To protect the environment adequately and to provide the protection at minimum cost to society .More and better knowledge is needed concerning the effect of pollution on plants ,animals and human beings and how to minimize their response.
Impact of Air pollution on Plans
*G.S.Singh and S.Chattopadhyay**
*E-Mail:Jayaraj625@yahoo.co.in
Central Tasar Research & Training Institute,Nagri,Ranchi,
**Department of Forest Science, Birsa Agricultural University,
Kanke, Ranchi
Air pollution can be defined as the presence in the atmosphere of substance or substances added directly or indirectly by an act of man, in such amounts as to affect humans, animals vegetation or materials adversely. Plants are very suitable for detecting, monitoring and mitigating air pollution effects. Air pollutants interact with plants and alter their normal functioning.
People have made many changes the world the live in and some of these have had harmful consequences. As the word population increase, there is more need for bigger cities, new town and farming land .Land has to be cleared, destroying the habitats many animals and plants. Some of these are now extinct other are in danger .Hunting has also has put animals in danger.
There is now nearly three times as much desert in the world as there was in 100 years ago. This is partly due to farmer over grazing their animals on the meager grass and shrubs and to clearance of the wood land trees for fire wood.
Industrialization is major threat to the environment. Pollution is just one example. Factories discharge harmful chemical into rivers and seas, killing fish and plants
The production of chlorofluorocarbons (CFCs) is reckoned to be responsible for damaging the ozone layer ,the protective layer , in the earth’s atmosphere that prevents harmful rays from the sun reaching the surface.CFCs are synthetic chemicals used in aerosol sprays and refrigerators. When they are released in atmosphere, they destroy the ozone. There is now whole in the ozone layer above Antarctica
Air pollution is caused by fumes and smoke from vehicles, factory chimneys and power station .Poisonous gases, such as Sulphur dioxide, mix with rain and mist to produce acids. When the acid rain falls, it kills plants over a wide area. Burning fuels also causes a build-up of carbon dioxide.
Carbon dioxide and CFCs are both green house gases. In the right amounts,
green house gases in the atmosphere trap heat from the sun so the earth
is not too hot or too cold. But if the green house gases build up, too
much heat is trapped and the earth becomes s warmer. This change in
the climate is known as global warming, could have disastrous effect.
The ice in the polar region may melt, causing severe flooding to low
lying area Changes in the climatic pattern world wide could lead to
violent storms and long draughts.
Impact of air pollutant combination on plants
Normal, clean air consist of complex mixtures of gases and suspended
mater, polluted air like wise consists of mixtures, a single pollutant
gas ,such as Sulphur dioxide, may be the predominant pollutant
Impact of atmospheric pollution on natural Ecosystem:
Air pollution injury to plants can be evident in several ways. Injury to foliage may be visible in a short time and appear as necrotic lesions (dead tissue), or it can develop slowly as a yellowing or chlorosis of the leaf. There may be a reduction in growth of various portions of a plant. Plants may be killed outright, but they usually do not succumb until they have suffered recurrent injury.
The effect s of air pollutants in the plants and other eco systems, Guderian(1977) presents the type of the extent of effects on various levels of ecosystem organization as follows :
1. Accumulation of pollutants in the plants and other ecosystems components (such as soil and surface-and ground water).
2. Damage to consumers as a result of pollutant accumulation (e.g.fluorosis).
3. Changes in species diversity due to shift in competition.
4. Disruption of biogeochemical cycles.
5. Disruption of stability and reduction in the ability of self –regulation.
Mechanism of air pollution and influence on ecosystem
The long term influence of air pollution on an ecosystem is result of:
1. Direct influence of gaseous pollutants, acid deposition, and particulates especially on the assimilatory apparatus of plants and the respiratory organs of animals, as well as on soil and even on climatic conditions.
2. Indirect influence on the individual components of eco- systems due to alteration by air pollution of the stage or function of these components.
Pollutant uptake by plants
Oxidants
Ozone is the main pollutant in the oxidant smog complex. Its effect on plants was first observed in the Los Angeles area in 1944. Since then, ozone injury to vegetation has been reported and documented in many areas throughout North America, including the southwestern and central regions of Ontario. Throughout the growing season, particularly July and August, ozone levels vary significantly. Periods of high ozone are associated with regional southerly air flows that are carried across the lower Great Lakes after passing over many urban and industrialised areas of the United States. Localized, domestic ozone levels also contribute to the already high background levels. Injury levels vary annually and white bean, which are particularly sensitive, are often used as an indicator of damage. Other sensitive species include cucumber, grape, green bean, lettuce, onion, potato, radish, rutabagas, spinach, sweet corn, tobacco and tomato. Resistant species include endive, pear and apricot.
Figure 1. Ozone injury to soybean foliage.
Ozone symptoms (Figure 1) characteristically occur on the upper surface of affected leaves and appear as a flecking, bronzing or bleaching of the leaf tissues. Although yield reductions are usually with visible foliar injury, crop loss can also occur without any sign of pollutant stress. Conversely, some crops can sustain visible foliar injury without any adverse effect on yield.
Susceptibility to ozone injury is influenced by many environmental and plant growth factors. High relative humidity, optimum soil-nitrogen levels and water availability increase susceptibility. Injury development on broad leaves also is influenced by the stage of maturity. The youngest leaves are resistant. With expansion, they become successively susceptible at middle and basal portions. The leaves become resistant again at complete maturation.
Lead:
It is naturally present, in small amounts, in soil, rocks, surface waters, and the atmosphere. Roadside environments are grossly contaminated with lead, as motor vehicles combusting gasoline containing lead alkalis release approximately 80 mg of lead per k.m. driven.
Carbon monoxide:
It is formed in all combustion process as result of the incomplete oxidation of carbon. Atmospheric carbon monoxide content are the maximum during winter and spring and at a minimum during the summer .Over past two decade s winter concentrations have tended to increase while in summer levels have remained constant.
Sulphur dioxide and Hydrogen Sulphide
Soils have a large capacity to absorb the sulphur dioxide quickly from atmosphere. Factors that tend to increase to the soil uptake of sulphur dioxide include fine texture, high soil organic content, high ph, presence of free Caco3, high soil moisture content, and the presence of soil microorganisms (Nyborg, 1978). Sulfur Dioxide
Major sources of sulfur dioxide are coal-burning operations, especially those providing electric power and space heating. Sulfur dioxide emissions can also result from the burning of petroleum and the smelting of sulfur containing ores.
Sulfur dioxide enters the leaves mainly through the stomata (microscopic openings) and the resultant injury is classified as either acute or chronic. Acute injury (Figure 2) is caused by absorption of high concentrations of sulfur dioxide in a relatively short time. The symptoms appear as 2-sided (bifacial) lesions that usually occur between the veins and occasionally along the margins of the leaves. The colour of the necrotic area can vary from a light tan or near white to an orange-red or brown depending on the time of year, the plant species affected and weather conditions. Recently expanded leaves usually are the most sensitive to acute sulfur dioxide injury, the very youngest and oldest being somewhat more resistant.
Figure 2. Acute sulfur dioxide injury to raspberry. Note that the injury occurs between the veins and that the tissue nearest the vein remains healthy.
Chronic injury is caused by long-term absorption of sulfur dioxide at sub-lethal concentrations. The symptoms appear as a yellowing or chlorosis of the leaf, and occasionally as a bronzing on the under surface of the leaves.
Different plant species and varieties and even individuals of the same species may vary considerably in their sensitivity to sulfur dioxide. These variations occur because of the differences in geographical location, climate, stage of growth and maturation. The following crop plants are generally considered susceptible to sulfur dioxide: alfalfa, barley, buckwheat, clover, oats, pumpkin, radish, rhubarb, spinach, squash, Swiss chard and tobacco. Resistant crop plants include asparagus, cabbage, celery, corn, onion and potato.
Because of its high solubility in water ,large amount of Sulphur dioxide are absorbed on external trees surface when the are wet .In dry condition Sulphur dioxide is readily absorbed by the tree leaves and rapidly oxidized in sulphate in there mesophyll cells (Bennettand Hill1975)
Fluoride
Fluorides are discharged into the atmosphere from the combustion of coal; the production of brick, tile, enamel frit, ceramics, and glass; the manufacture of aluminium and steel; and the production of hydrofluoric acid, phosphate chemicals and fertilizers.
Fluorides absorbed by leaves are conducted towards the margins of broad leaves (grapes) and to the tips of monocotyledonous leaves (gladiolus). Little injury takes place at the site of absorption, whereas the margins or the tips of the leaves build up injurious concentrations. The injury (Figure 3) starts as a gray or light-green water-soaked lesion, which turns tan to reddish-brown. With continued exposure the necrotic areas increase in size, spreading inward to the midrib on broad leaves and downward on monocotyledonous leaves.
The fluoride enters the leaf through the stomata and is moved to the margins where it accumulates and causes tissue injury. Note, the characteristic dark band separating the healthy (green) and injured (brown) tissues of affected leaves.
Studies of susceptibility of plant species to fluorides show that apricot, barley (young), blueberry, peach (fruit), gladiolus, grape, plum, prune, sweet corn and tulip are most sensitive. Resistant plants include alfalfa, asparagus, bean (snap), cabbage, carrot, cauliflower, celery, cucumber, eggplant, pea, pear, pepper, potato, squash, tobacco and wheat.
Ammonia
Ammonia injury to vegetation has been observed frequently in Ontario in recent years following accidents involving the storage, transportation or application of anhydrous and aqua ammonia fertilizers. These episodes usually release large quantities of ammonia into the atmosphere for brief periods of time and cause severe injury to vegetation in the immediate vicinity.
Complete system expression on affected vegetation usually takes several days to develop, and appears as irregular, bleached, bifacial, necrotic lesions. Grasses often show reddish, interveinal necrotic streaking or dark upper surface discolouration. Flowers, fruit and woody tissues usually are not affected, and in the case of severe injury to fruit trees, recovery through the production of new leaves can occur (Figure 4). Sensitive species include apple, barley, beans, clover, radish, raspberry and soybean. Resistant species include alfalfa, beet, carrot, corn, cucumber, eggplant, onion, peach, rhubarb and tomato.
Figure 4. Severe ammonia injury to apple foliage and subsequent recovery through the production of new leaves following the fumigation.
Particulate Matter
Particulate matter such as cement dust, magnesium-lime dust and carbon soot deposited on vegetation can inhibit the normal respiration and photosynthesis mechanisms within the leaf. Cement dust may cause chlorosis and death of leaf tissue by the combination of a thick crust and alkaline toxicity produced in wet weather. The dust coating (Figure 5) also may affect the normal action of pesticides and other agricultural chemicals applied as sprays to foliage. In addition, accumulation of alkaline dusts in the soil can increase soil pH to levels adverse to crop growth.
Figure 5. Cement-dust coating on apple leaves and fruit. The dust had no injurious effect on the foliage, but inhibited the action of a pre-harvest crop spray.
Some other information:
1. Plant uptake rates increase as the solubility of the pollutants in water increases.
2. When vegetative surface are wet the pollutant removal rate** may increases up to 10 fold. Under damp condition the entire above ground plant surface leaves, twigs, branches, and stems is available for uptake.
3.Pollutant are absorbed most in efficiently by plants foliage near the canopy surface, where light- mediated metabolic and pollutant diffusivity rates are greatest.
4. Sulphur and nitrogen dioxides are taken up by respiring leaves in the dark, but uptake rates are greatly reduced relative to rates in the light.
To protect the environment adequately and to provide the protection at minimum cost to society .More and better knowledge is needed concerning the effect of pollution on plants ,animals and human beings and how to minimize their response.
\
Controlling of atmospheric pollution
The danger of environment that is posed by air borne pollution is caused
by many operations of heavy industry-primarily in metals and the chemistry
of energy production (whether based on brown or black coals
,peat, or oil) Controlling of atmospheric pollution at the source.
The basic factor in protecting plants is to reduce emission s to non injurious levels. This is complex problems but it can be solved by various means* such as using the most appropriate raw materials for industry, optimizing locations of industrial plants and using the most modern technologies for efficient reduction of emissions.
Reduction of photochemical oxidant emission
Reduction of oxides of nitrogen in industrial emissions
Reduction of hydrogen fluoride emission by industrial plants
Chemical treatments of plants;
The use of chemical compound for protecting plants against air pollution will not replace efforts to reduce emissions at the source.
Fertilization: The effect of mineral fertilization in reducing plant sensitivity to air pollution is dependent on many sites, climatic, and gentic, factors. Plants may be more sensitive when grown under condition of under of low nutrition than high.
Protectant compounds:
The use chemical compounds in reducing plant injury caused by air pollution has been greatest interest .pollutant emissions are often very difficult to control at the source ,and of the necessity ,endangered plants have to be protected at the site of cultivation. The mechanisms of action of chemical compounds protecting plants from air pollution, or reducing injury, are much diversified. Some break down ozone and other photochemical oxidants on leaf surface. This can be attained by using anti oxidants and anti-ozonates. The protecting compound may also reduce sensitivity of plants by changing their metabolism (Koiwai etal., 1974)
Pollutant concentrations injurious to the plants
Two types of damage are recognized, acute and chronic
Acute damage
It occurs as result of the action of high concentrations of gasses over a short period of time .When the poisonous gasses reach the plants cells ,the latter natural physiological and biochemical process are altered Accumulation of large quantities of poisonous substances lead s to injuries to leaf blades, the formations of necrosis ,and eventually to the rapid dying of the plants( Taylor,1973)
Chronic damage:
It occurs when low concentrations of polluting gasses act for a longer
period of time .This leads to reduction in growth and development
of plants and consequently of the crop, without any initially
visible injuries(Feder,1973;Linzon,
To protect
the environment adequately and to provide the protection
at minimum cost to society .More and better knowledge is needed
concerning the effect of pollution on plants ,animals
and human beings and how to minimize their response
Reference:
Nyborg,M.(1978)Sulphur pollution
and soils.pp.359-90 in Sulphur in the
environment ,part II;Ecological impacts(Ed.J.O.Nriagu).Wiley,
.
Taylor,O.C.(1973).Acute response
s of plants to aerial pollutants.Pp.9-21
in air pollution damage to vegetation (Ed.J.A.Naegele).American
chemical society ,Washington,Dc.USA:137pp.
Feder,W.A.(1973).Cumulative
effect.pp.21-31 in Air pollution damage to vegetation
. of chronic exposure of plants to low level of pollution.
American Chemical Society Washington,Dc.USA:137pp.
Linzon ,S.N.(1978) Effect of
air borne Sulphur pollutants on plants .pp110-162 in Sulphur in
the environment, Part II:Ecological impacts (Ed.J .C.Nriagu)John
Wiley & Sons ,Chicester ,England ,UK 482pp.
Koiwai,A.,kitano,H.,Fucuda
,M.andKisaki,T.(1974).
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