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Urban Pollution and Solution
By: S.C. Sharma*
In modern times pollution has
become the biggest menace for the survival of the biological species. There are
various types of pollution e.g. air, water, soil, sound and mental pollution.
Earth was a beautiful landscape but man has ruthlessly exploited for his greed
specially, in the last century. With rapid industrialization and random
urbanization environmental pollution has become a serious problem. Over
exploitation of open spaces, ever-increasing number of automobiles and
demographic pressure have further aggravated the problem. There are various ways
and means to mitigate the urban environmental pollution. Plan-ting of trees and
shrubs for abatement of pollution and improvement of environment is an effective
way and well recognized throughout the world. Earlier, the purpose of planting
trees in urban areas was purely aesthetic. The incessant increase of urban
environ-mental pollution has necessitated to reconsider the whole approach of
urban landscaping and its orientation in order to achieve duel effect i.e.
bio-aesthetics and mitigation of pollution. Proper planning and planting scheme
depending upon the magnitude and type of pollution, selection of pollution-
tolerant and dust scavenging trees and shrubs should be done for bioremediation
of urban environmental pollution. Pollution, the major problem in cities, is
compounded by the fact that there is no exhaust for the polluted air to escape.
Landscape architects can solve the pollution problems related to urban landscape
by creating a micro-climate.
Planting along the road
Roads are the important sites of
the urban areas which contribute significantly in generating pollution. By
planting trees on both sides pollution can be mitigated. Unfortunately, in most
of the old Indian cities and towns, there is hardly any provision of sufficient
space for the same. However, it is necessary to study the type of road, overhead
electrical cables, spaces available on both sides, central verge, traffic
triangles, round-abouts, squares and other open space available before taking up
any plantation. It has been observed that trees and shrubs which are
drought/frost resistant are generally tolerant to pollution. Selection of trees
is another important task. Before selecting any plant species, it is necessary
to consider following characters: agro-climatic suitability; height and spread;
canopy architecture; growth rate and habit (straight undivided trunk); aesthetic
effect (foliage, conspicuous and attractive flower colour); pollution tolerance
and dust scavenging capacity. Some of the ornamental trees which have aesthetic
effect and are tolerant to pollution have been screened and recommended for
planting along the roads: Acacia auriculiformis, Ailanthus excelsa,
Albizzia lebbek, Bauhinia acumi nat a, B. purpurea, But ea
monosperma, Cassia fistula, C. marginata, C. siamea, Casuarina
equisetifolia, Crataeva religiosa, Drypetes roxburghii, Ficus benjamina,
Lagerstroemia duperreana, L. flosreginae, L. rosea, Mimusops elengi,
Polyalthia longifolia, P. longifolia 'Angustifolia', P. longifolia 'Pendula',
Peltophorum ferrugineum, Tectona grandis, Terminalia arjuna, T.
muelleri, Thespesia populnea etc. Emphasis should be given to the native plant species which are
comparatively well acclimatized, and stress and pollution tolerant.
Central Verge
Central verge of the two way
roads in the cities and towns are often found neglected and devoid of any
planting. It is recommended that this area should be well utilized by planting
dwarf trees and shrubs. This will not only serve aesthetic purpose but also
functional being physical barrier for the glare of head lights of the vehicles
which is essential for effective and safe operation of the roads during dark
hours. Planting may be done either in single or double row depending upon the
space available. Since these plants are more close to the automobile exhaust,
their capacity for pollution tolerance should be considered before selection.
Following plant species have been reported as pollution tolerant and recommended
for plantation: Acalypha wilkesiana, Bougainvillea 'Chitra', 'H.C.
Buck', 'Lady Mary Baring', 'Mary Palmer Special', 'Partha', 'Shubhra', 'Zulu
Queen'; Caesalpinia pulcherrima, Callistemon lanceolatus, C. polandii,
Cassia surattensis, Duranta plumeri, Euphorbia milli, Hamelia patens,
Hibiscus rosa-sinensis, Ixora coccinea, J atropha panduraefolia, Lantanacamara, L. depressa, Malpighia cocci ger a, M. glabra, Murraya
paniculata, Nerium oleander , Phyllanthus niruri, Rosa Gruss an
Teplitz', Tabernaemontana coronaria, Thevetia neriifolia, Vinca rosea,
Wadelia lacinata etc.
Traffic Island
Traffic islands at the main road
intersections vary in shape and size from square, triangle to round. Whatever
may be the shape, these islands should be properly planted with the dwarf trees,
shrubs and ground covers recommended for planting along the road and central
verge which will contribute effectively in mitigating the air pollution.
Greenbelt
Greenbelt
is defined as the mass plantation of pollution tolerant trees and
shrubs in an area for the purpose of minimizing air pollution by filtering, intercepting and absorbing pollutants in an effective manner for improvement of the environment. Every town and city must have certain area earmarked for the development of greenbelts. The effectiveness of the greenbelt depend on
several factors viz. climatic
conditions, design, selection of plant species and its characters and type of pollutants. The importance of greenbelt can be ascertained from the estimate of cleansing capacity of 3.7 tonnes of CO2 from atmosphere and supply of 2.5 tonnes of oxygen from one hectare of woodland. Following trees and shrubs are recommended for planting in the greenbelt which have aesthetic effect as well as pollution tolerant capacity:
Acacia auriculiformis, Albizzia lebbek, Azadirachta indica, Bougainvillea cultivars, Bauhinia purpurea, Butea monosperma, Cassia siamea, C.
surattensis, Dalbergia sissoo, Ficus infectoria, Diospyros embryopteris,
Lagerstroemia duperreana, Melia azedarach, Millingtonia hortensis, Murraya
paniculata, Nerium oleander, Nyctanthes arbortristis, Parkinsonia aculeata,
Polyalthia longifolia, Putranjiva roxburghii, Terminalia arjuna, T. muelleri,
Thevetia neriifolia etc.
Considering the present scenario of urban environmental pollution, there is a growing need for changing the approach of planting trees and other plant species. Inclusion of the ornamental plants having pollution mitigating ability in the landscape plan will serve the duel purpose of making the cities green and pollution free in the
long run. Proper planting scheme will
bring healthy life and colour in the cement concrete jungle of large congested
cities. There is an urgent need for saving Lucknow, the beautiful city of
Gardens which is being converted into a dead city of stone by ill planning and
short sightedness. Solution lies in having a strong and selfless political will.
There should be a nodal agency for coordination of the arboricultural activities
of the Forest Department, Horticulture Department, Municipal Corporation,
Lucknow Development Authority, NGOs , Landscape Architects, Environmentalist and
strong media. Sincere efforts will transform Lucknow into a 'Model Green
Capital' having 30% forest cover within the next five years. Governments may go
and come but the momentum should be maintained, so the citizens may feel healthy
and happy. Our city, Lucknow is well known all over the world for its culture
and friendliness.
*Vice-President, International Society of Environmental Botanists, National
Botanical Research Institute, Lucknow-226001, India
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