B.D. Tripathi

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.

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.

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.

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.

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.

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.

Heavy metal contamination of soil, and bioaccumulation in vegetables irrigated with treated waste water in the tropical city of Varanasi, India

The present study was conducted to determine the heavy metal contamination in soil with accumulation in plants in waste water irrigated areas. Results revealed that waste water contained lower concentrations of Cr, Zn, Cu, and Pb except Cd (0.03) than the permissible limits prescribed by the World Health Organization. The maximum metal concentrations occurred in Brassica oleracea (Zn 63.80, Cu 12.25, Cr 10.65, Pb 3.63, and Cd 0.56 mg Kg−1).The metal enrichment (EF of Cd 1.9, Cr2.9, Zn 4.8, Cu 6.5, and Pb 15.5) and degree of contamination (CF of Cd 2.9, Cr 2.0, Zn 2.3, Cu 2.7, and Pb 2.2) showed that accumulation of the five toxic metals increased during sewage irrigation as compared with the reference values, other Indian regions and globally. However, based on WHO standards for heavy metal contamination of soil and irrigation water, our data does not ensure safe levels for food.

Magnetic Properties of Vehicle-derived Particulates and Amelioration by Ficus infectoria: A Keystone Species

Magnetic minerals derived from vehicular combustion are mainly maghemite and metallic iron grains having a size range of 0.1–0.7 lm (1). This grain size is particularly dangerous to humans because of its ability to be inhaled into the lungs. Moreover, in aerosols, magnetite is associated with other heavy metals such as zinc, cadmium, and chromium (2) and with mutagenic organic compounds (3) dangerous to human health. In the atmosphere, magnetic minerals are derived from combustion processes, such as industrial, domestic, or vehicle emissions (4, 5) or from abrasion products from asphalt and from vehicles’ brake systems (6). The magnetic fine particles mostly consist of spherules and grains of irregular shapes that contain variable amounts and grain sizes of magnetite and hematite, depending on the fuel type and temperature of combustion (7). Magnetic properties of soils (6, 8, 9, 10), filters (11, 12), and leaves (2, 7) have been used to identify the spread of pollution derived from vehicular or industrial emissions. Iron often occurs as an impurity in fossil fuels during industrial, domestic, or vehicle combustion; carbon and organic material are lost by oxidation and the iron forms a nonvolatile residue, often comprising glassy spherules (due to melting). These spherules are magnetic, with easily measurable magnetization levels. It has been shown that combustion processes simultaneously release hazardous substances and magnetic particles into the atmosphere. In addition to these combustion-related particles, vehicles, via exhaust emissions and abrasion/ corrosion of engine and/or vehicle body material (13), can generate nonspherical magnetite particles. Leaves with large surface areas per unit of weight, favorable surface properties (a waxy coating), and a long lifespan, such as conifer needles or evergreen tree leaves, are considered to be good accumulators of particulate matter from the atmosphere (14–16). Rainwater containing particles collected from the atmosphere could either contribute to dust accumulation on leaf surfaces or, by detaching previously collected particles, cause its reduction. Magnetic biomonitoring of pollutants by measurements taken from roadside tree leaves is potentially efficient, as samples are abundant and hundred of samples can be collected and analyzed in days. The study region (Singrauli industrial area lies in between latitudes 23852N to 24832 N and longitudes 82830 E to 83825 E) is one of the India’s most important energy centers. Eleven opencast coal mines, occupying nearly 200 km, fuel six thermal power stations that generate 6800 MW of power (10% of India’s installed generation capacity). Sampling locations lie in between latitudes 2480812 N to 248 0952 N and longitudes 828 4425 E to 828 4541 E.

Physico-chemical characterization of city sewage discharged into river Ganga at Varanasi, India

Abstract The Varanasi city sewage discharged into the river Ganga at six sites, Assi ghat, Shiwala ghat, Harishchandra ghat, Chauki ghat, Rajendra Prasad ghat, and Rajghat was analysed for its physicochemical properties such as temperature, pH, acidity, alkalinity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, chloride, electrical conductance, nitrate and phosphate. An analysis of variance reveals significant variation in most of the parameters with respect to months as well as sites. Duncans multiple-range test shows that a higher concentration of sewage was discharge during May and June. Furthermore, at Rajghat, sewage was the most concentrated with the highest pollution load, whereas sewage at Assi ghat was the least concentrated. The correlation among various parameters is reported.

Atmospheric dustfall deposits in Varanasi City

Abstract Monthly variations in dustfall concentration was studied in the city of Varanasi, India, during 1988. For dustfall samples collection, special dustfall jars were set up at three different sites at a height of approximately 20 m above the ground in and outside the city. Collected dust deposits were chemically analysed and the results are briefly discussed. A comparison was made between these sites and concluded that the maximum concentration was found at Parav and the minimum at Banaras Hindu University. In addition, water soluble and water insoluble fractions were detected in dust deposits. A seasonal variation in concentrations was also observed.