Welcome to National Botanical Research Institute: NBRI Lucknow

R & D Area > Biomass Biology & Environmental Sciences

Eco-Auditing

Group Leader	Dr. (Mrs.) Nandita Singh, Sci 'C'
Contact	Work	91-522- 2205842
	Home	91-522- 2221687, 2283554
	Fax	91-522- 2205842

Introduction

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.

Background

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.

R & D Programmes and major achievements

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.

Studies in and around thermal power stations and coal fired industries

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 features^{9, 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^-1sulphur 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 undertaken^{26,

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.

Monitoring of auto-exhaust pollution by Roadside plants

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 air^{11, 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 concentration^3-4.

Impact Assessment of Air Pollutants on the Flora and Soil in Meghalaya

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

Site No	Stations	Pollutant conc. (mg m-3)
Site No	Stations	SPM	SO2	NOx	Pb
1.	Shillong - Police Bazar	146.8	41	52	0.76
2.	Shillong – Ward’s lake	120.6	32	34	0.42
3.	Jowai	164.4	48	49	0.61
4.	Cherrapunjee	60.2	29	26	0.50
5.	Dawki	56.4	28	34	0.52
6.	Umiam lake	20.2	20	26	0.40

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.

Assessment of fly ash for growth of plants

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 area^18-27.

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.