Assessment of Air Pollution Tolerance Index of some plants to develop vertical gardens near street canyons of a polluted tropical city.

The aim of the present study was to examine Air Pollution Tolerance Index (APTI) of some climber plant species to develop vertical gardens in Varanasi city which has characteristics of tall building and narrow roads. This condition results in street canyon like structure and hinders the vertical dispersal of air pollutants. We have selected 24 climber plant species which are commonly found in of Varanasi city. Chosen plants can be easily grown either in planter boxes or directly in the ground, with a vertical support they can climb on walls to form green walls or vertical garden. Air Pollution Tolerance Index (APTI) of the selected plant species was calculated and plants with higher APTI are recommended for the development of Vertical garden. Highest APTI was noted for Ipomoea palmata (25.39) followed by Aristolochia elegans (23.28), Thunbergia grandiflora (23.14), Quisqualis indica (22.42), and Clerodendrum splendens (22.36). However, lowest APTI value (8.75) was recorded for the species Hemidesmus indicus. Moreover, the linear regression analysis has revealed a high positive correlation between APTI and ascorbic acid content (R2=0.8837) and positive correlation between APTI and Chlorophyll content (R2=0.6687). On the basis of higher APTI values (greater than 17), nine species of climber plants viz. I. palmata, T. grandiflora, C. splendens, A. elegans, Q. indica, Petria volubilis, Antigonon leptopus, Cryptolepis buchuanni and Tinospora cordifolia have been recommended to develop vertical greenery systems in a compact tropical city.

Assessment of metal species in river Ganga sediment at Varanasi, India using sequential extraction procedure and SEM-EDS.

Aim of the present study was to assess impact of urban drains over river water and sediments by physico-chemical and metal analysis. Metal speciation (Sequential Extraction Procedure) and elemental composition analysis (SEM-EDS) was used to quantify metal pollution load in river sediments. Metal speciation analysis showed dominance of available and labile fractions of all heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) except Mn and Fe which were dominant in residual forms. Cluster analysis (CA), Principal Components Analysis (PCA) and Partial Least Square Regression (PLSR) were applied as source receptor modeling for pollutants. Results classified river stretch into three zones i.e. moderately, severely and extremely polluted, on the basis of pollutant concentration released from anthropogenic sources. SEM-EDS study revealed the elemental composition percentage in river sediments. Pollution Load Index (PLI) varied from 1.8 (S1)-3.9 (S15). The Geo accumulation index (GAI) was found highest for Cd (6.88-8.97) and Pb (2.41-3.24).

Application of chemometric analysis and self Organizing Map-Artificial Neural Network as source receptor modeling for metal speciation in river sediment.

Present study deals with the river Ganga water quality and its impact on metal speciation in its sediments. Concentration of physico-chemical parameters was highest in summer season followed by winter and lowest in rainy season. Metal speciation study in river sediments revealed that exchangeable, reducible and oxidizable fractions were dominant in all the studied metals (Cr, Ni, Cu, Zn, Cd, Pb) except Mn and Fe. High pollution load index (1.64-3.89) recommends urgent need of mitigation measures. Self-organizing Map-Artificial Neural Network (SOM-ANN) was applied to the data set for the prediction of major point sources of pollution in the river Ganga.

Efficiency of Phragmites australis and Typha latifolia for heavy metal removal from wastewater.

A cost-effective and promising technology has been demonstrated for the removal of copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), iron (Fe), lead (Pb) and zinc (Zn) from urban sewage mixed with industrial effluents within 14 days. With the help of P. australis and T. latifolia grown alone and in combination batch experiments were designed to assess the removal of heavy metals from the wastewater collected from 5 sampling stations. The results revealed that P. australis performed better than T. latifolia for Cu, Cd, Cr, Ni, Fe, Pb and Zn removal, while mixing of the plant species further enhanced the removal of Cu to 78.0±1.2%, Cd to 60.0±1.2%, Cr to 68.1±0.4%, Ni to 73.8±0.6%, Fe to 80.1±0.3%, Pb to 61.0±1.2% and Zn to 61.0±1.2% for wastewater samples from Raj Ghat. Negative correlation coefficients of Cu, Cd, Cr, Ni, Fe, Pb and Zn concentrations in wastewater with the retention time revealed that there was an increase in the heavy metal removal rate with retention time. P. australis showed higher accumulative capacities for Cu, Cd, Cr, Ni and Fe than T. latifolia. P. australis and T. latifolia grown in combination can be used for the removal of Cu, Cd, Cr, Ni, Fe, Pb and Zn from the urban sewage mixed with industrial effluents within 14 days.

Source apportionment of wastewater pollutants using multivariate analyses.

A faster and cost-effective methodology has been developed to estimate the spatial and seasonal variations in wastewater quality and apportion the influencing sources through multivariate statistical techniques, cluster analysis and principal component analysis (PCA). Partially treated or untreated wastewater is released into the river from various industrial and domestic sources, which poses a serious threat to human health. Wastewater samples were collected from five stations along the river bank. PCA performed on overall wastewater samples revealed that in present study all the five sampling stations were influenced by sewage and industrial effluents mixed together. However, the pollutant levels were significantly different in the three groups of wastewater samples, which were confirmed by univariate analysis of principal component (PC) scores. Based on wastewater similarities, cluster analysis identified three groups (central, upstream and downstream) of sampling stations, which further confirmed univariate analysis of PCs scores. Spatial variations in wastewater quality reveled that the highest pollutant concentration was noted for group 1 and lowest for group 2. Seasonal variations in the wastewater quality revealed that highest values of pollutants were observed in low flow and lowest in high flow. Results of the present study obtained through multivariate analyses may be used to classify wastewater and identify the influencing sources of pollutants. The present study may be useful in reducing 11 % of the cost in future investigations. Thus, in future quality estimation of the representative wastewater samples would be faster as well as cost-effective approach.

Chemometric characterization of river water quality.

Various industrial facilities in the city of Varanasi discharge their effluent mixed with municipal sewage into the River Ganges at different discharge points. In this study, chemometric tools such as cluster analysis and box-whisker plots were applied to interpret data obtained during examination of River Ganges water quality. Specifically, we investigated the temperature (T), pH, total alkalinity, total acidity, electrical conductivity (EC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), nitrate nitrogen (N), phosphate (PO 4(2-) ), copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), iron (Fe), lead (Pb), and zinc (Zn) in water samples collected from six sampling stations. Hierarchical agglomerative cluster analysis was conducted using Ward's method. Proximity distance between EC and Cr was the smallest revealing a relationship between these parameters, which was confirmed by Pearson's correlation. Based on proximity distances, EC, Cr, Ni, Fe, N, COD, temperature, BOD, and total acidity comprised one group; Zn, Pb, Cd, total alkalinity, Cu, and phosphate (PO 4(2-) ) were in another group; and DO and pH formed a separate group. These groups were confirmed by Pearson's correlation (r) values that indicated significant and positive correlation between variables in the same group. Box-whisker plots revealed that as we go downstream, the pollutant concentration increases and maximum at the downstream station Raj Ghat and minimum at the upstream station Samane Ghat. Seasonal variations in water quality parameters signified that total alkalinity, total acidity, DO, BOD, COD, N, phosphate (PO 4(2-) ), Cu, Cd, Cr, Ni, Fe, Pb, and Zn were the highest in summer (March-June) and the lowest during monsoon season (July-October). Temperature was the highest in summer and the lowest in winter (November-February). DO was the highest in winter and the lowest in summer season. pH was observed to be the highest in monsoon and the lowest in summer season.

Efficiency of combined process of ozone and bio-filtration in the treatment of secondary effluent.

The present work was aimed at studying the efficiency of the combined process of biofiltration with ozonation to improve the quality of secondary effluent. The secondary effluent from the Dinapur Sewage Treatment Plant Varanasi, India was used in this work. The process of biofiltration with the plant species of Eichornia crassipes and Lemna minor, at a flow rate of 262 ml min(-1) and plant density of 30 mg L(-1) for 48 h, in combination with the process of ozonation with ozone dose of 10 mg L(-1) and contact time of 5 min was applied. Results revealed that combined process was statistically most suitable for the highest degradation of physico-chemical and microbial parameters with improving BDOC value. The biofiltration process is able to remove highest percentage of toxic heavy metals from the secondary effluent without production of toxicity. This technique is highly recommendable for tropical wastewater where sewage is mixed with industrial effluents.

Application of ozone based treatments of secondary effluents.

The present work was aimed at studying the efficiency of ozone in oxidation processes, coliform inactivation and Disinfection Byproducts (DBPs) formation, associated with the potential of ozone to increase the Biodegradable Dissolved Organic Carbon (BDOC) in secondary effluent with applied ozone doses of 5.0, 10.0 and 15.0 mg/L for contact times of 2, 5 and 10 min. The wastewater used in this work was collected from the Bhagwanpur Sewage Treatment Plant, Varanasi, India. Results of this experiment showed that 10 mg O(3)/L O(3) for 5 min exposure was found most suitable dose for highest degradation of COD, TOC, UV(254), color, turbidity and total nitrogen parameters. The inactivation range of microbial biomass range was found in between 95% and 98%. Experiment revealed the fact that aldehydes and carboxylic acid formation were significantly related with the ozone dose and exposure time and ozone might enhance the treatment efficiency of secondary effluent treatment.

Removal and accumulation of mercury by aquatic macrophytes from an open cast coal mine effluent.

In this study, the mercury (Hg) removal capacities of two aquatic macrophytes, Pistia stratiotes and Azolla pinnata, were investigated against the coal mining effluent. These plants reduced mercury from the effluent via rhizofiltration and subsequent accumulation in plant. The removal rate of P. stratiotes and A. pinnata was 80% and 68%, respectively, after 21 days of exposure to the effluent containing 10 microg L(-1) of Hg. As mercury from the effluent was accumulated in the root and shoot tissues of both aquatic macrophytes, they were proven to be a root accumulator with a translocation factor of less than one during the entire study. The decreasing Hg content in effluent (from 10 to 2.0 microg L(-1)) was reflected by its accumulation in roots (0.57+/-0.02 mg g(-1) in P. stratiotes) and leaves of the experimental plants (0.42+/-0.01 mg g(-1), P. stratiotes). As a result, Hg concentrations in the coal mining effluent were tightly associated with those observed from macrophytes. Considering the high removal efficiencies of Hg by these aquatic macrophytes, these plants can be recommended for the actual treatment of Hg-containing waste waters.

Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India.

The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L(-1). The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R(2) = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO(3-) and PO(4)(3-)) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.

Accumulation of chromium and zinc from aqueous solutions using water hyacinth (Eichhornia crassipes).

Under present investigation Eichhornia crassipes (water hyacinth) has been tested for removal of two important heavy metals chromium (Cr) and zinc (Zn) from metal solution. This species was grown at four concentrations of Cr and Zn, i.e. 1.0, 5.0, 10.0 and 20.0 mg l(-1) in single metal solution. This plant has performed extremely well in removing the Cr and Zn from their solution and was capable of removing up to 95% of zinc and 84% of chromium during 11 days incubation period. Removal of Cr at lower concentrations (1.0 and 5.0 mg l(-1)) was found harmless, without any symptom of toxicity but at 10.0 and 20.0 mg l(-1), plants have shown some morphological symptoms of toxicity. On the other hand E. crassipes removed Zn safely at all the four concentrations, i.e. 1.0, 5.0, 10.0 and 20.0 mg l(-1). In this case morphological symptoms of toxicity were not evident in the test plant. Biochemical parameters viz. protein, sugar and chlorophyll in experimental plants have shown a decreasing trend due to accumulation of Zn and Cr. Overall this methodology is safe for the removal of Zn and Cr and can be utilized at large scale after few further investigation.

Biochemical responses in tree foliage exposed to coal-fired power plant emission in seasonally dry tropical environment.

A biomonitoring study was conducted to investigate the responses of plants exposed to power plant emission in a dry tropical environment. For this purpose, five sampling sites were selected in the prevailing wind direction (NE) at different distance to thermal power plant (TPP) within 8.0 km range and a reference site was selected in eastern direction at a distance of 22.0 km. The two most common tree species, Ficus benghalensis L. (Evergreen tree) and Dalbergia sisso Roxb. (deciduous tree) were selected as test plants. Ambient sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), suspended particulate matter (SPM), respirable suspended particulate matter (RSPM), dust-fall rate (DFR) and plant responses such as leaf pigments (chlorophyll a, chlorophyll b and carotenoids), ascorbic acid, sugar and sulphate-sulphur (SO4(2-)-S) contents were measured. Ambient SO(2), NO(2), SPM, RSPM and DFR showed significant spatial and temporal variation at different sites. Considerable reduction in pigment (chlorophyll a, chlorophyll b and carotenoids) and sugar contents were observed at sites receiving higher pollution load. Ascorbic acid exhibited significant positive correlation with pollution load. Accumulation of SO4(2-)-S in leaf tissue showed significant positive correlation with ambient SO(2) concentration at all the sites. At the same time, SO4(2-)-S showed significant negative correlation with pigment and sugar content. D. sisso Roxb. tree was found to be more sensitive as compared to F. benghalensis L. tree.

Assessment of atmospheric PAHs profile through Calotropis gigantea R.Br. leaves in the vicinity of an Indian coal-fired power plant.

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) in the leaves of Calotropis gigantea R.Br. were performed at seven sites in the surrounding areas of a Thermal Power Plant (TPP), using the gas chromatography and mass spectrometry technique. The primary objective of the study was to monitor the degree of PAHs load in the nearby sites around TPP compared to distant sites. Total PAH (SigmaPAH) concentrations in the leaves ranged from 372.18 (at control site 7) to 4362.35 ng g(-1) d.w. (at highest polluted site 4). The concentration factors ranged from 2.65 to 11.72 for the sites located at 1 km to the point source and 1.0 to 7.08 for distant sites. The share of carcinogenic PAHs to the total PAHs differed with the site, ranging from 10.76% to 26.92%. The sites located closer to TPP have shown higher concentrations of medium and high molecular weight PAHs, which decreased gradually with the distance from the source. The total PAH burden at control site was dominated by the low and medium molecular weight PAHs compounds viz., naphthalene, acenaphthylene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene, coronene., whilst at other sites medium and high PAHs viz., fluoranthene, pyrene, benzo (a) anthracene, chrysene, benzo (b) fluoranthene, benzo (e) pyrene and coronene showed the highest values. These results support the biomonitoring ability of Calotropis gigantea R.Br. leaves to monitor PAHs contamination.

Distribution of vehicular pollutants in street canyons of Varanasi, India: a different case.

In present study horizontal and vertical distribution of traffic-related pollutants (CO and SO(2)) within the street canyons in (CO and SO(2)) Varanasi, India was monitored. The results showed that average horizontal profiles of traffic-related pollutant concentrations within street canyon at leeward side were approximately same as that of windward side. However, the vertical concentration of both the pollutants decreases with height above the ground and study indicated that CO and SO(2) concentrations at different heights below the roof showed clear vertical self-gradient. CO and SO(2) concentration decreased with height and the minimum value occurred at the roof. It was concluded from the observed results that pollutants from vehicular exhaust emissions in the street canyon of Varanasi were evenly distributed. This result may be due to the fact that wind vortices are not formed. Therefore, urban planners can use this type of streets so that there is proper ventilation and dispersal of pollutants.

Bioaccumulation of heavy metals and two organochlorine pesticides (DDT and BHC) in crops irrigated with secondary treated waste water.

Four crop plants Oryza sativa (rice), Solanum melongena (brinjal), Spinacea oleracea (spinach) and Raphanus sativus (radish) were grown to study the impact of secondary treated municipal waste water irrigation. These plants were grown in three plots each of 0.5 ha, and irrigated with secondary treated waste water from a sewage treatment plant. Sludge from the same sewage treatment plant was applied as manure. Cultivated plants were analyzed for accumulation of heavy metals and pesticides. Results revealed the accumulation of six heavy metals cadmium (Cd), chromium (Cr), iron (Fe), copper (Cu), nickel (Ni), and zinc (Zn) as well as two pesticides [1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane; DDT] and benzene hexa chloride (BHC). Order of the plants for the extent of bioaccumulation was S. oleracea > R. sativus > S. melongena > O. sativa. The study has shown the secondary treated waste water can be a source of contamination to the soil and plants.

Effect of ambient air sulphur dioxide on sulphate accumulation in plants.

Present study deals with the relationship between ambient air sulphurdioxide and sulphate content in leaf of selected tropical plant species, Ficus religiosa. The study reveals a positive correlation between ambient air sulphur dioxide and sulphate in the leaves. Two way ANOVA finds the obtained values to be highly significant (p < 0.001). Amount of sulphate in leaves shows positive correlation with sulphur dioxide in air (p < 0.001) during most part of the study A marked reduction of sulphate content in leaf was found during October when reduction in ambient air sulphur dioxide was recorded.

Assessing the genotoxicity of urban air pollutants in Varanasi City using Tradescantia micronucleus (Trad-MCN) bioassay.

In the present study Tradescantia micronucleus (Trad-MCN) bioassay was performed to assess the genotoxicity of air pollutants in Varanasi City. The experiment was performed during October 2006 to April 2007. For Tradescantia micronucleus (Trad-MCN) bioassay four sites were selected, three in the city having different traffic characteristics and one control site virtually free from traffic intervention. Twenty young Tradescantia pallida inflorescences were collected from each sampling site during the study period and micronuclei frequencies were determined in early tetrads of pollen mother cells and expressed as MCN/100 tetrads. During the same period the concentration of different air pollutants were also measured. Tradescantia micronucleus (Trad-MCN) bioassay showed that the plants kept in areas having higher traffic emissions evidence higher micronuclei frequencies than samples kept at control site. The study indicates that in situ biomonitoring using higher plants may be useful for characterizing genotoxic air pollutants in areas even without any sophisticated instrument.

Seasonal variation of leaf dust accumulation and pigment content in plant species exposed to urban particulates pollution.

To assess the dust interception efficiency of some selected tree species and impact of dust deposition on chlorophyll and ascorbic acid content of leaves the present study was undertaken. The plant species selected for the study were Ficus religiosa, Ficus benghalensis, Mangifera indica, Dalbergia sissoo, Psidium guajava, and Dendrocalamus strictus. It was found that all species have maximum dust deposition in the winter season followed by summer and rainy seasons. Chlorophyll content decreased and ascorbic acid content increased with the increase of dust deposition. There was significant negative and positive correlation between dust deposition and chlorophyll and ascorbic acid content, respectively. Maximum dust interception was done by Dalbergia sisso and least by Dendrocalamus strictus. Thus plants can be used to intercept dust particles which are of potential health hazards to humans.

Concurrent removal and accumulation of heavy metals by the three aquatic macrophytes.

Under the present investigation effectiveness of three aquatic macrophytes Pistia stratiotes L. (water lettuce), Spirodela polyrrhiza W. Koch (duckweed) and Eichhornia crassipes were tested for the removal of five heavy metals (Fe, Zn, Cu, Cr and Cd). These plants were grown at three different concentrations (1.0, 2.0 and 5.0mgl(-1)) of metals in laboratory experiment. Result revealed high removal (>90%) of different metals during 15 days experiment. Highest removal was observed on 12th day of experiment, thereafter it decreased. Results revealed E. crassipes as the most efficient for the removal of selected heavy metals followed by P. stratiotes and S. polyrrhiza. Results from analysis confirmed the accumulation of different metals within the plant and a corresponding decrease of metals in the water. Significant correlations between metal concentration in final water and macrophytes were obtained. Plants have accumulated heavy metals in its body without the production of any toxicity or reduction in growth. Selected plants shown a wide range of tolerance to all of the selected metals and therefore can be used for large scale removal of heavy metals from waste water.