No abstract

The ability of seven hyperaccumulator macrophytes which grow naturally in the heavy metal contaminated channels of three different industries (Hindustan Aeronautical Ltd., Eveready Ltd., and Scooter India Ltd.) to accumulate heavy metals was recorded. All these industries use electroplating processes in their manufacturing and are located in the inner area of Lucknow City, U.P., India. Of the three industries monitored, effluent released from Eveready Ltd. contained the highest concentration of heavy metals. In general, accumulations of heavy metals depend upon the plant species and the metal concentration in the media. All plant samples showed heterogeneous metal accumulations, except for Fe or Cd. It was observed that some plant species accumulated high level of metals, e. g., Eichhornnia crassipes for Fe (4052.44 lg/g), Mn (788.42 lg/g), and Cu (315.50 lg/g), and Spirodela polyrhiza for Cd (12.75 lg/g), Pb (20.25 lg/g), and Cr (128.27 lg/g), even when the metal concentrations were not high in the effluent. In summary, these two plants were found to be the best accumulators at each contaminated site. The results will be helpful in the selection of plant species which can be used as bioaccumulators or bioindicators.

In the present study, the toxicity assessment of tannery effluent was carried out in terms of percent phytotoxicity and shoot/root dry weight ratio. The effluent used in the study was collected from the outlet of an effluent treatment plant situated in the Jajmau area of Kanpur, U. P. India. Three varieties each of rice (Surya-52, Jaya-14 and Pant-10), pulses (Lens-(Type-9), Gram Bahar, and Mung-C-K-851) and oil seeds (Mustard RS-30, B-9 and T-69) containing different kinds of reserve food materials, i. e., starch, protein and fat were taken for the toxicity study. The accumulations of heavy metals, i. e., Cr, Cu, Zn, and Ni, by these different crop varieties through pot culture irrigated with effluent were estimated at maturity. The concentration of heavy metals in the effluent was found to be Cr = 0.135, Cu = 0.065, Zn = 0.052, and Ni = 0.036 mg/L. The maximum concentration found in the plant tissue was seen in the mustard variety RS 30, i. e., Cr = 15.2, Cu = 4.4, Zn = 3.2, and Ni = 2.6 lg/g dry weight (d.w.) and the minimum concentration was found in Gram Bahar, i. e., Cr = 8.5, Cu = 2.0, Zn = 1.6 lg/g d.w., whereas, in 0.98 lg/g d.w. of Ni was found in the Surya rice variety. The percent phytotoxicity was found to be in the range of 10.4 to 25.6% amongst the different test varieties. The average percent phytotoxicity was found to be highest in rice followed by oilseed and pulses. The shoot/root dry weight ratio ranged between 10.82 to 14.22, with the highest value seen for rice (Pant-10) and the lowest for a pulse (Gram-Bahar). The results revealed that cultivation of these crops irrigated with the tannery effluent may pose a potential risk to humans as well as animals because of their bioaccumulation properties and ability to transfer metals from one trophic level to the next trophic level through the food chain. Since the percent phytotoxicity and shoot/root dry weight ratio behaves in a similar manner for the effluent, these parameters can be considered for the assessment of toxicity of industrial effluents.

Heavy metal contamination of the rivers is a world wide environmental problem and its removal is a great challenge. Kanpur and Unnao two closely located districts of Uttar Pradesh India are known for their leather industries. The tanneries release their treated effluent in the near by water ways containing Cr metal that eventually merges with the river Ganges. Untreated tannery effluent contains 2.673 +/- 0.32 to 3.268 +/- 0.73 mg l(-1) Cr. Microbes were isolated, keeping the natural selection in the view, from the tannery effluent since microbes present in the effluent exposed to the various types of stresses and metal stress is one of them. Investigations include the exposure of higher concentrations of Cr(VI) 1.0 to 4.0 mg l(-1) to the bacteria (presumably the Pseudomonas spp.) predominant on the agar plate. The short termed study (72 h) of biosorption showed significant reduction of metal in the media especially in the higher concentrations with a value from 1.0 +/- 0.02, 2.0 +/- 0.01, 3.0 +/- 0, and 4.0 +/- 0.09 at zero h to 0.873 +/- 0.55, 1.840 +/- 1.31, 2.780 +/- 0.03 and 3.502 +/- 0.68 at 72 h respectively. The biosorption of metal show in the present study that the naturally occurring microbes have enough potential to mitigate the excessive contamination of their surroundings and can be used to reduce the metal concentrations in aqueous solutions in a specific time frame.

A bioassay technique was used to select plant species that were able to germinate and grow in a site contaminated with flash torch and battery manufacturing industrial effluents. Three varieties each of rice, namely Surya-52, Jaya-14 and Pant-10; three varieties of pulses [Gram (Bahar), Mung (K-851) and Lens (T-9)] and three varieties of oilseeds (Mustard-RS-30, Mustard-B-9 and Mustard T-69) were used for the determination of phytotoxicity by bioassay technique. The average % phytotoxicity for rice was 18.03% (14.34-22.7%), for pulses was 15.76% (8.75-26.64%) and for oil seed was 11.09% (6.42-15.24%). Accumulation of metals (Cu, Fe, Mn, Cd, Cr and Pb) was estimated in the root, shoot and edible parts of different crop varieties grown in pot culture up to maturity and treated with industrial effluent. The concentration of different metal ions in root, shoot and edible parts were in the range of Cu: 9. , 0.78-2.25 lg/g d.w. respectively. A higher concentration of Cd was found in Surya-52 rice variety and in Gram (Bahar) pulse variety and of Pb was detected in Surya-52 rice variety. Cd and Pb are non-essential metal ions and highly toxic to plants. Accumulation of toxic metal ions like Pb and Cd in the edible parts of oil a seed variety may not exceed the recommended daily intake limits. Percentage phytotoxicity and inhibition of root and shoot length was also less in the oil seed variety. Thus these plant varieties can be considered for cultivation in fields contaminated by waste from the flash-torch and batterymanufacturing industry.