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Eco-Auditing |
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Introduction
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Science and technology of the 20th century came as a ‘mixed blessing’ for mankind.
It brought peace and prosperity, comfort, health and wealth for mankind through
rapid utilization of the natural environmental resources but also threatened the
‘ecological security’ of the earth due to ‘over-utilization’ and ‘indiscriminate
exploitation’ of the scarce and ‘non-renewable resources’ with consequent damage
to the ecosystem and generation of huge ‘wastes and pollutants’ as the by-products
of development.
Clearly, the new paradigm of development is not a game of economics. Issues – ecological,
social, political, cultural and technological – have to be given due consideration
to evolve an environment based on the principals of sustainable development.
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Background
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It was during the dynamic tenure of Professor T N Khoshoo (1981) that seeds of Environmental
Sciences were sown after Indian Science Congress presentation by Dr Khoshoo and
Dr. K.J. Ahmad held at BHU, Varanasi in the section on “Impact of the Development
of Science & Technology on Environment”. However, the group was still known
as Plant Anatomy (working on epidermal studies), however research on environmental
sciences had begun under the leadership of Dr. K. J. Ahmad. It was during the tenure
of Dr. P. V. Sane (1984-1997) that the current nomenclature of Environmental Botany
was assigned to the group when Dr. Sane realized that sufficient and relevant work
has been done to give this nomenclature. Major thrust for researches in Environmental
Sciences was provided by Prof. T.N. Khoshoo as Secretary, Ministry of Environment
when he sanctioning an All India coordinated project on plant and environmental
pollution.
Dr. P. Pushpangadan, during 1999, introduced Eco auditing as an emerging group.
The group focuses on various activities including eco-auditing, eco-monitoring,
and eco-remedies.
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R & D Programmes and major achievements
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Eco auditing group is involved in R & D on eco- monitoring, environmental impact
assessment, eco-friendly models that are technologically and economically feasibly
for phyto remediation of polluted lands and polluted waters etc.
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Studies in and around thermal power stations and coal fired industries
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A study was undertaken under All India Co-ordinated Programme on Air Pollution and
Plants sponsored by the Ministry of Environment and Forests (MoEF)2.
Under this programme, a detailed investigation was carried out to study the effects
of pollutants (chiefly SO2, fly ash and particulates) emitting from coal
burning, on plants. The study included (i) vegetational surveys, (ii) transplant/transfer
experiments and (iii) laboratory experiments19.
Vegetational surveys were carried out in and around brick-klin complexes, locomotive
workshop, loco running shed and power stations. Throughout these surveys, an assessment
of the extent of damage by air pollutants, to the common economic and ornamental
plants was made.
Transplant studies were carried out by placing potted plants of Baugainvillea, Chrysanthemum,
Tabernaemontana coronaria, Catharanthus roseus6, Phlox drummondii, Aster
amellus and Tropaelum majus, in and around the Thermal power stations and
were observed for their growth, vigour, flowering and fruiting. The plants were
listed as sensitive or tolerant to thermal power pollution.
A comparative study of the foliar surface configuration and cuticular and epidermal
features9, 14 was carried out, both under light and scanning electron
microscopes. The study revealed that number of leaf surface characters respond to
air pollution and they can be used as bioindicators of air pollution. The traits,
useful for bio-indication are: epicuticular wax (degree of deposition, ornamentation,
etc.), cuticle (thickness, configuration, striations, folds, etc.), epidermal cells
(frequency, size, cell wall thickening, injury, necrotic lesions, particulates,
crystals, etc.), stomata (frequency, size, abnormal stomata), trichomes (size, frequency,
disorganization), other features (idioblasts, cystoliths), etc.
Relative sensitivity and tolerance of some Gadiolus cultivars22 to sulphur
dioxide in another program. Five Gladiolus cultivars namely ‘Aldebaran’,
‘Bright eye’, ‘Illusion’, ‘Manisha’ and ‘Manmohan’ were exposed to 1 and 2 µg l-1
sulphur dioxide. Plants were fumigated experimentally for 2 h daily. Foliar
injury symptoms were observed first in ‘Manisha’ followed by ‘Aldeberan’ and ‘Illusion’
at the higher dose. Photosynthetic pigments and leaf extract pH were significantly
decreased, particularly in ‘Manisha’ and ‘Illusion’. Overall disturbances in the
plant metabolism due to SO2 treatment led to retard growth of plants,
as evident from decreased shoot length and phytomass. The taxa was found to be relatively
sensitive.
The buffering capacity / neutralizing ability of the plant leaf help in combating
acidic pollution23. A study was undertaken26, 28 to compare
the buffering capacity/acid neutralizing ability of the foliage of five woody plant
species viz., Bauhinia malabarica L., Bougainvilles cv ‘Mahara’, Cassia
fistula, Citrus limon and Ficus riligiosa. Leaf segments were placed in
simulated rain solutions of pH 5.67, 4.15, 3.16 and 2.62 and pH measurements were
taken at intervals of 0.5, 1, 2 and 4 hr. The pH in acid rain solutions increased
rapidly in the beginning and later on slowly, after the leaf tissues were placed
in the acid solutions. Leaching of organic (sugar, proteins and aminoacids) and
inorganic (Ca+2, K+, and Mg+2) substances from
the leaf surfaces of all plant species increased corresponding to increase in acidity
of acid rain. It was hypothesized that K+ and Ca+ played an
important role in neutralizing the acid rain on plant foliage. The observation of
visual injury showed that there was no correlation between the acid neutralizing
ability of a plant species and degree of leaf injury. However, the buffering capacities
of all the plant species corresponded to their acid neutralizing ability indicating
a positive correlation between the buffering and acid neutralizing ability of all
plant species. On the basis of acid neutralizing ability, of the plant foliage,
the plant species were placed in the following order:
C. fistula>F. religiosa>C. limon> Baugainvillea>B. malabarica.
Based on intensive vegetational surveys, supplemented with the transplant and laboratory
experiments, a list of 50 species of pollution tolerant flowering plants has been
prepared. Fourteen sensitive plant species have also been identified which can be
used as bioindicators of air pollutants. Plant species listed under tolerant or
sensitive heads are mainly relevant to pollutants emanating from thermal power plants
and coal-fired10 industries (chiefly SO2 and particulates)
and have been studies in the agro-climatic conditions of north Indian plains. Most
common tolerant and sensitive species are mentioned below:
Pollution tolerant Plants: Acacia arabica Willd. (‘Kateria babul’), Adhatoda
vasica Nees (‘Adusa’), Aegle marmelos Correa (‘Bel’), Ailanthus excelsa
Roxb. (‘Mahaneem’), Albizzia lebbek Benth. (‘Siris’), Alstonia scholaris
R.Br. (‘Chitwan’), Antigonon leptopus Hook. et Arn., Argyreia speciosa
Sweet, Azadirachta indica A. Juss. (‘Neem’), Bougainvillea spectabilis
Willd., Citrus medica L. (‘Lemon’), Clitoria ternatea Linn. (‘Aparajita’),
Dalbergia sissoo Roxb. (‘Shisham’), Ficus benghalensis L. (‘Bargad’),
F. infectoria Roxb. (‘Pakar’), Hibiscus rosa-sinensis L. (‘Gurhal’),
Lagerstroemia flos-reginae (‘Jarul’), Lantana camara L. (‘Ghaneri’),
Leucaena macrophylla Benth. (‘Subobul’), Madhuca indica J.F. Gmel.
(‘Mahua’), Mimusops elengi Sieber ex A. DC. (‘Maulsri’), Murraya paniculata
Jack. (‘Kamini’), Nerium indicum Mill. (‘Lal Kaner’), Phoenix sylvestris
Roxb. (‘Khajur’), Phyllanthus emblica L. (‘Amla’), Pithecolobium dulce
Benth. (‘Jangal Jalebi’), Polyalthia longifolia Benth. & Hook. (‘Ashok’),
Quisqualis indica L. (‘Rangoon creeper’), Tabernaemontana coronaria
Willd. (‘Chandni’), Tamarindus indica L. (‘Imli’), Catharanthus roseus
L. (‘Sadabahar’), Zizyphus mauritiana Lam. (‘Ber’).
Pollution Sensitive Plants: Anthocephalus cadamba Miq. (‘Kadamb’), Brassica
campestris L. (‘Mustard’), Delonix regia Raffin. (‘Gulmohar’),
Bauhinia variegata (‘Kachnar’), Cassia fistula L. (‘Amaltas’),
Morus alba L. (‘Shahtoot’), Mangifera indica L. (‘Aam’), Litchi
chinensis Sooner. (‘Lichi’), Medicago sativa L. (‘Barseem’).
This list has been made available to a number environmental agencies like Pollution
Control Boards, Ministry of Environment and Forests, State Environment Departments,
State Department of Urban Development, Forest Department and Industries, NGOs, which
are concerned with plantation on urban and industrial sites to help in mitigating
dust and air pollution.
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Monitoring of auto-exhaust pollution by Roadside plants
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The major pollutants emitted from automobiles are CO2, CO, oxides of
nitrogen, SO2 heavy metals (particularly Pb), unburnt hydrocarbon,carbon
particles and water vapours. Vegatation and soils are important sinks for atmospheric
pollutants. The vegetative components of the ecosystems are also useful biomonitors
of atmospheric pollutant deposition. A study was undertaken to authenticate the
relationship between the Pb and SO4 levels in foliage and SO2
and Pb load in air11, 21.
According to the correlation analysis the Pb25 and sulphate content in
leaves and the Pb and SO2 concentration in the air have a positive relationship.
The intensity of the association between the two variables is represented by a correlation
coefficient. Among the plant species tested for Pb correlation, Delonix regia
and Holoptelea integrifolia did not show significant correlation whereas
Eucalyptus and Thevetia showed a reliability factor at the 0.05
level. Using the reliability factor of p<0.001 to test correlation coefficients
(sulphate in leaves x SO2 in air), the species in which correlation was
positive are Azadirachta indica, Bougainvillea sp., Callistemon lanceolatum, Calotropis
procera, Dalbergia sissoo, Eucalyptus sp., Tabernaemontana coronaria
and Thevetia nerifolia. Thers was non-significant correlation in Polyalthia
longifolia1.
Reliability analysis was performed using Pb and sulphate content in leaves to estimate
Pb and SO2 concentration respectively in air. The results revealed that
Dalbergia sissoois an ideal tree species to monitor and indicate the Pb concentration
in air. Other species which were found suitable for monitoring are Azadirachta indica,
Bougainvillea sp., Cassia fistula, Calotropis procera
and Tabernaemontana coronaria. To estimate SO2 in air, Calotropis
procera was found to be the most suitable plant species. Other ideal species
are Azadiracta indica, Callistemon lanceolatum and Dalbergia sissoo.
These plants can be used for monitoring Pb and SO2 in the cities and
around industries. They can be used as early warning systems20.
The changing levels of lead (Pb) in the soil and vegetation along two national highways
near Lucknow (India) were investigated. The pattern of lead deposition, as reflected
by soil Pb burdens, showed decrease in concentration with increasing distances from
the road margins. At both the sites, Pb concentration was above background concentration
even at the soil core depth of 15 cm. Oryza sativa, Colocasia esculentum, Luffa
cylindrica and Cynodon dactylon contained a high mean concentration.
Milk samples, collected from cattle that normally graze on the roadside pasture-lands
dominated by Cynodon dactylon, contained Pb at an elevated concentration3-4.
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Impact Assessment of Air Pollutants on the Flora and Soil in Meghalaya
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During the past two decades the Meghalaya state has witnessed a significant increase
in population growth. The developmental activities have also stepped up under the
various five-year plans. A spurt in human activities and concomitant increase in
demand for natural resources have led to over-use and over-exploitation of natural
resources resulting in depletion of forest cover, destruction of natural habitats
of plants and animals, degradation of land and deterioration in quality of environment.
The change in environment is disrupting the delicately balanced ecological processes
in the fragile hill ecosystem, which ultimately lead to loss of biological diversity29.
There are very few industries in Meghalaya although being rich in mineral and other
natural resources. A thorough survey of Shillong and neighbouring districts was
conducted to ascertain the major causes of air pollution in Meghalaya. Due to poor
industrial development the state as such does not face the problem of air pollution.
However certain pockets need attention for high air pollution24. Detailed
study was conducted for: Automobile exhaust pollution; Maumluh Cherra Cement Limited,
Cherrapunji; Lime Stone; & Rat hole mining.
Shillong being the only Class I city in the State has the highest population in
Meghalaya. The increasing trend of urbanization of the city is largely due to migration
from predominantly rural areas. Besides this, the inter-state migration has also
contributed to the growth of urban center. National Highway 40, an all weather road,
connects Shillong with Guwahati. State buses and private transport operators have
services to various places in Meghalaya. This has increased the number of vehicles
many fold, which is increasing the automobile exhaust pollution in Meghalaya. This
is further worsened due to steep slopes and height in the hills.
The concentration of three major air pollutants viz., suspended particulate matter
(SPM), sulphur dioxide (SO2), oxides of nitrogen (NOx) and Pb concentration
were studied (Table 1) for different locations in Meghalaya to depict the quality
of ambient air.
Table 1
Level of major pollutants in the ambient air at different stations in Meghalaya
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Site No
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Stations
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Pollutant conc. (mg m-3)
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SPM
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SO2
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NOx
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1.
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Shillong - Police Bazar |
146.8 |
41 |
52 |
0.76 |
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2.
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Shillong – Ward’s lake |
120.6 |
32 |
34 |
0.42 |
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3.
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Jowai |
164.4 |
48 |
49 |
0.61 |
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Cherrapunjee |
60.2 |
29 |
26 |
0.50 |
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5.
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Dawki |
56.4 |
28 |
34 |
0.52 |
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6.
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Umiam lake |
20.2 |
20 |
26 |
0.40 |
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Maumluh Cherra Cement Factory , Cherrapunjee, is the only large industry in the
state. Its capacity of production is 930 tons day -1. Most sources of
pollution from this industry have been checked by using different /devices by Meghalaya
State Pollution Control Board, Shillong. In spite of pollution control equipments
there is a lot of fugitive emissions from the factory. These emissions emit a large
amount of cement dust into the atmosphere which in due course of time settles on
the plant and soil surfaces. Study showed that plant species growing near the factory
were severely affected showing foliar injury, reduced leaf area, and very poor growth.
This is probably due to the fact that this site receives maximum dust which falls
on the plant and soil surface, thereby directly or indirectly affecting the plant
growth. The soil pH of the polluted sites was alkaline (pH 7.4) in nature whereas
the normal soil has pH was acidic (pH 6.0). Leaf extract pH also increased in these
plants probably due to the penetration of the alkaline solution of cement through
stomata or cuticle on the upper surface and injured the cells beneath. The shift
in cell sap pH may interfere with the biochemical activities of leaves. The reduction
in leaf area can be attributed to decreased photosynthetic ability of the dusted
plants due to the formation of an impervious crust on the leaf surface which hampered
both leaf growth and expansion.
The lime stone crushers are found throughout the state. The limestone are excavated
from the hillocks by indeginous methods which exposes a lot of compact soil leading
to dust pollution as well as degradation of the land.
Chlorophyll and carotenoids content decreased in dust polluted sites in comparison
to control. Concentration of Fe increased in the leaves of bamboo at all the polluted
sites. Some increase in metal was also found in pine. Pb and Zn did not show any
significant change. The unscientific method used by crushers are not only polluting
the area they are also degrading the land.
The Meghalaya state has a deposits of 560 million tones of coal distributed over
20 coalfields and covering an area of about 285 km2 Data source – Directorate
of Mineral Resources, Meghalaya). The coal mining activity is becoming the major
cause of concern from the point of view of degradation of land in the state. Coal
mining is done by primitive labour – intensive method, popularly known as ‘rat hole’
mining. Major problems associated with rat-hole mining were evaluated. These are:
(i) formation of new habitats, called colliery spoils, which lack structure because
of up-side –down change in the position of soil horizons and haphazard mixing of
coal particles. (ii) deposition of coal particles both in wet season (through waster
seapage) and dry season (through wind) on the land which is not directly hit by
mining operation, like abandoned and cultivated agricultural fields. The acidic
condition of soil inhibits the activity of microorganisms : Low pH also increases
the solubility of phytotoxic elements (Al3+, Mn2+, Fe2+,
Fe3+). The soil in the paddy fields also showed low pH and phosphorus
content when being irrigated by the runoff of the mine. Due to heavy rains almost
throughout the year the soluble material of coal mine spoils get dissolved in rain
water and enter into the nearby streams and adjoining paddy fields. Mine seepage
is also used to irrigate the field, which has high concentration of metals. This
is adversely affects the crop growth.
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Assessment of fly ash for growth of plants
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Fly ash is disposed off either through the wet method (slurry form) or the dry method
(ash ponds). Fly ash disposal is a major concern for the thermal power plants as
the fly ash dumps are the cause of air, water and soil pollution in the area18-27.
Studies was undertaken to elucidate the possibility of fly-ash application to agriculture
soils to improve crop yields. Three different amounts of fly-ash (2,4 and 8% w/w)
were mixed with soil in 1 m2 plots and seeds of Beta vulgaris
were sown in these soil-amended plots. Plants and soils were sampled at 20, 40,
60 and finally at 80 days and analysed with respect to plant growth and yield and
concentration of elements both in under and above- ground parts. The results revealed
that fly-ash applications, particularly in higher amounts ( 4 and 8% w/w) increased
the pH and conductivity of the soils to undesirable levels, however, the application
of low amounts favoured plant growth and improved yields. Although the elements,
viz. Cd, Cu, Fe, Mn, Ni and Pb accumulated in larger quantities in plants grown
in fly ash amended soils than the control, their levels remained well below the
threshold limit and, thus, are suitable for human consumption at the lowest fly-ash
application rate. The increase in the sugar content at the low fly-ash application
rate in beet root, the second most important crop for sugar extraction, enhances
the possible use/ application of fly-ash in tested amounts, in improving crop yields12.
Experiments were also undertaken to utilize the fly ash for the growth of plants.
Helianthus annuus L. were raised on the soils13 amended with
fly-ash at the rate of 0.5 kg, 1kg and 1.5 kg per m2 plot. Plants were
sampled thrice at 20, 40, and 60 day plant age from the day of sowing. None of the
treated plants showed any visible injury symptoms either of nutrient deficiency
or toxicity. The additions of fly ash to soils at all the three levels promoted
the plant growth as evidenced by increased leaf area and phytomass of the treated
plants and as compared to control plants. Root-shoot ratio was generally lower for
all sets of treated plants than for untreated plants. While relative growth rate
and net assimilation rate showed a significant increase at 60- day age. Leaf area
ratio and specific leaf area of treated plants were always lower. Interestingly
leaf weight ratio was initially low but increased at later stages of plant growth.
Besides there was a significant increase in the dry flower weight of H1,
H2 plants as compared to control flowers. The results of the present study clearly
indicate that application of fly ash upto the level of 1.5 kg m2 enhanced
the growth and phytomass accumulation in sunflower plant.
Similarly, Cassia siamea Lamk was grown in garden soil (control), fly -ash
amended by various amelioration (cowdung manure, press-mud, garden soil; 1:1, w/w).
The plants survived in fly ash (100%) though their growth was less in comparision
to the treatments. Fly- ash + press mud (1:1, w/w) proved to be the best combination
growth (total biomass, leaf number, photosynthetic area, total chlorophyll, protein)
was significantly high in this treatment followed by cowdung manure and garden soil.
Leaves and root accumulated significant amount of Cu, Zn, Ni and Fe5.
However, the concentration of all the metals was more in roots than in leaves except
Ni. Although, fly -ash contains high amount of metals but the metal uptake was more
in plants grown in fly ash + press mud mixture. Inspite of high metal availability
in fly-ash and press mud mixture, plant growth was good. This might be attributed
to the some metal detoxification mechanism active in this treatment. It was concluded
that C. siamea seems to be suitable plant for developing a vegetation cover
on fly-ash dumps.
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