Virendra Kumar Mishra

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.

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.