The role of plants as indicator for air pollutionMuhammad Mahadi. Environmental Science Discipline. Khulna University.

Mobile No : 008801717838118

Introduction: A plant is used to indicate air quality and locate sources of air pollution utilizing known as air “Pollution Indicator Plant.” Indicator plants containing a series of chambers, where the particulate matter and chemicals have been removed by a series of filters. Bio-indicator plants are very sensitive to a selected (toxic) chemical, they respond quickly with typical visible foliar symptoms to the presence of medium-to-low levels of the noxious agent; they are very cost-effective and represent a striking visual demonstration unit. The category of plants as a indicator of air pollution are discussed below:

1. Lichen(Parmelia Orthotrichum, Polytrichum)2. Algae( Chlamydomonas, Chlorella, Chlorococcum, Chlorosarcina)3. Moss Tillandsia usneoides,Sphagnum, Bryum4. Herbs and grasses5. Tulsi6. Tobacco7. Lettuce plants

1. Lichen (Parmelia): For nearly 25 years that lichen growth and health can assess many air pollutants and the value of these living organisms rather than man-made instruments for assessing sulfur dioxide levels is that they are inexpensive and give quick results. Lichens are especially useful in forestry to assess where conifers should be planted since conifers are affected by the same sulfur dioxide levels that cause lichen cover to decline. The possibility of transplanting healthy lichens into areas suspected of being polluted, and monitoring physiological parameters such as respiration and photosynthesis, to give a rapid indication of pollution levels is obvious.

Lichen vegetation could assess air pollution levels was supported by Fenton (1960) while Trass (1971) was able to correlated a mean annual sulfur dioxide (SO2) value with his lichen index "P" to cover sulfur dioxide levels from less than 10 to 300 mg/m 3.

2. Algae: Aerial or sub-aerial algae would also be ideal as indicators of air pollution because of ease of handling, range of species specific sensitivity which is greater than in higher plants and much quicker physiological responses to air chemistry than occur in high plants. Many of the cortecolous, lithophilous and epiphytic algae, liverworts, fern gametophytes are ideally suited as air biological monitoring organisms. Using both pollution tolerant and pollution sensitive species would be best for air quality indication. Especially suitable as test organisms in the Air Biomonitor are the microalgae found in both aerial and subaerial habitats such as species of Chlamydomonas, Chlorella, Chlorococcum, Chlorosarcina, Chlorosarcinopsis, Gloeocystis, Chlorhormidium Pleurococcus,Stichococcus, Trebouxia, Chroococcus, Gloeocapsa, Nostoc, Oscillatoria, Schizothrix, and Scytonema and the diatoms- Navicula and Nitzschia.

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The role of plants as indicator for air pollutionMuhammad Mahadi. Environmental Science Discipline. Khulna University.

Mobile No : 0088017178381183. Moss (Tillandsia): Tillandsia usneoides is an indicator species to air pollution, that its

decline is directly related to raised levels of air pollution, and that the most acidic pollutants are the most harmful. Air pollutants are absorbed by Spanish moss. An experiment was formulated with two stages: the first, stage involved taking air samples in Houston and testing for the quantity of specific pollutants using a gas chromatograph and the second stage was putting Spanish moss in an Environmental Study Chamber (ESC), which is a closed system, and exposing it to the pollutants found in the air samples. Tillandsia usneoides, commonly called Spanish moss, is a relative of the pineapple (order Bromeliales, family Bromeliaceae, genus Tillandsia (air plant), and species usneoides) (Spanish moss). In fact, it is an epiphyte, a plant that gains all of its moisture and nutrients from the air (Arny). The thin trichomes (scales) that cover the whole plant, these trichomes play an important role in the absorption of moisture and nutrients from the air. The trachomas act as pumps, and draw moisture and dissolved minerals into the plants through the stomata (Arny). This indicates that whatever is present in the air—including pollutants—will be absorbed by the plants.

4. Herbs and grasses: Changes in sensitive species of herbs and grasses occur much earlier than in shrub and tree populations. Generally, the degree of ‘Crown die-back’ and death of trees is directly related to the level of SO2, NO2 HF and HCl pollution of air.

5. Tulsi: Tulsi is sensitive to pollution and a minor change in pollution level is also been detected by this plant. Certain visual observations on the plant supported our prediction that Tulsi can be used as effective bioindicator for autoexhaust pollution. Tulsi act as bio-indicator for determing the increased level of nitrogen and sulphur status in atmosphere.

6. Tobacco: Biomonitoring of ozone with tobacco is miniaturized kit based on tobacco seedlings (Nicotiana tabacum L.) cultivars Bel-W3 (O3-supersensitive) and Bel-B (O3-resistant). The biomonitoring units consisted of polystyrene tissue-culture plates with wells filled with organic compost; each well held a 10-day-old tobacco seedling, raised in a controlled environment.

7. Lettuce plants: Lettuce plants as bioaccumulations of trace elements Homogeneous adult lettuce plants, Lactuca sativa raised in a greenhouse were exposed to ambient air in 15 dm3 containers at nine stations and regularly provided with water until field capacity.

Plant species Reported sensitivity to pollutantsTobaccoBeansSquashWater melonTomatoLichens

O3

O3, So2

O3, So2

O3

O3

O3, So2, Nox

Table: Plant bio-indicators for determining the presence of air pollutants

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The role of plants as indicator for air pollutionMuhammad Mahadi. Environmental Science Discipline. Khulna University.

Mobile No : 008801717838118Conclusion: The rate of accumulation of air pollutants in the lichen, moss, tobacco, tulsi or algal plants can be determined by means such as biomass decrease or increase per unit time, pigment analysis, rate of respiration or photosynthesis and heavy metal or isotope accumulation.

Reference:

1. www.environmentofearth.wordpress.com/tag/pollution-indicator-plants

2. K C Agarwal. ‘Environmental Pollution Causes, Effects and Control’. 2001.

3. G K Ghosh. ‘Environmental Pollution ¾ Scientific Dimension’. 1992, New Delhi

4. www.rsc.org/ej/EM/2004/b316800j.pdf

5. www.ncbi.nlm.nih.gov/pubmed/15237296

6. http://en.wikipedia.org/wiki/Bioindicator

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