Bioaccumulation of toxic metals (Cr, Cd, Pb and Cu) by seeds of Euryale ferox Salisb. (Makhana) W

The level of toxic metals Cr, Cd, Pb and Cu was determined in seeds, water and sediments collected from nine closed waterbodies of Darbhanga, north Bihar, used for cultivation of the edible aquatic macrophyte Euryaleferox Salisb. during harvesting season of the crop for two successive years (1996 and 1997). Seeds bioconcentrated appreciable amount of these toxic metals in the order Pb > Cr > Cu > Cd. The increased load of metal pollution due to domestic and municipal discharges threatened the habitats of the plant. The toxic metal contents in seeds were found positively correlated with the ambient concentration of metals in water and sediments. The importance of these findings has been discussed for national water resource economy of the country and human health perspectives.     

Groundwater Quality Assessment of Tehsil Kheragarh, Agra (India) with Special Reference to Fluoride

Fluoride concentration and other parameters in groundwater from 261 villages in Tehsil Kheragarh of District Agra were assessed and attempts were made to observe the relationship between fluoride and other water quality parameters. Of 658 groundwater samples (collected from separate sources) analysed for fluoride, 27% were in the range of 0–1.0 mg/L, 25% in 1.0–1.5 mg/L, 32% in1.5–3.0 mg/L and 16% above 3.0 mg/L. The highest fluoride concentration recorded was 12.80 mg/L. Significant correlation of fluoride with pH, alkalinity, Na, SiO₂ and PO₄ were observed. Factor analysis was also attempted in order to identify the contributing sources.     

Metal biomonitoring in water resources of Eastern Ghats,Koraput (Orissa), India by aquatic plants

Biomonitoring of toxic metals in the water resources used by indigenous tribal communities in Koraput district, Orissa, India was carried out under the National Technology Mission Project. Most of the water bodies catering for the day-to-day needs of the local inhabitants were found to contain high concentrations of Fe and Mn in addition to Cr, Cd, Pb and Cu. The water bodies supported by a great number of phytodiversity and the plants growing therein accumulated significantly high amounts of these toxic metals, submerged plants being more efficient than floating ones. The species like Chara corallina and Spirogyra spp. showed significant potential to magnify Cd and Pb in their tissue several times more than the concentrations in surrounding water. The levels of metals in the plants occurring at places where the metal content is very high could be used for indicating the status of water.NBRI Research Publication No. (437) NS.     

Distribution of metals in aquatic edible plants: Trapa natans (Roxb.) Makino and Ipomoea aquatica Forsk

Most of the water bodies being used for the cultivation ofedible aquatic plants (Trapa natans and Ipomoeaaquatica) in Lucknow district, U.P., India, were found to becontaminated with a variety of toxic metals (Fe, Cu, Cr, Mn andPb). The concentration of metals Cr, Pb and Fe in water was muchhigher than recommended permissible limits of WHO (1995). Theedible parts of these plants bioconcentrated metals from theirsurrounding water significantly. Therefore, the present studywas planned to assess the metal concentration in edible part ofplants which was collected from various water bodies used forcultivation of these crops. Despite varying levels of metalsfound in various fruit parts of T. natans, the metalaccumulation in kernel was alarming. However, metal contentdecreased significantly in various parts after boiling thefruit. Similarly, I. aquatica also accumulatedsignificantly higher amounts of these metals in leaves, howeverthe metal accumulating potential varied considerably dependingupon level of metal contamination in the water body in which they were growing. The importance of these findings in theexploitation of these aquatic crops to meet the demand of foodand health perspectives for human beings is highlighted.     

Heavy metals in water, sediments and wetland plants in an aquatic ecosystem of tropical industrial region, India

Concentrations of heavy metals (Cu, Cr, Fe, Pb, Zn, Hg, Ni, and Cd) and macronutrients (Mn) were measured in industrial effluents, water, bottom sediments, and wetland plants from a reservoir, Govind Ballabh (G.B.) Pant Sagar, in Singrauli Industrial region, India. The discharge point of a thermal power plant, a coal mine, and chlor-alkali effluent into the G.B. Pant Sagar were selected as sampling sites with one reference site in order to compare the findings. The concentrations of heavy metals in filtered water, sieved sediment samples (0.4-63 microm), and wetland plants were determined with particle-induced X-ray emission. The collected plants were Aponogeton natans, L. Engl. & Krause, Cyperus rotundus, L., Hydrilla verticillata, (L.f.) Royle, Ipomoea aquatica, Forssk., Marsilea quadrifolia, L., Potamogeton pectinatus, L., Eichhornia crassipes, (Mart.) Solms Monogr., Lemna minor, L., Spirodela polyrhiza (L.) Schleid. Linnaea, Azolla pinnata, R.Br., Vallisneria spiralis, L., and Polygonum amphibium, L. In general, metal concentration showed a significant positive correlation between industrial effluent, lake water, and lake sediment (p < 0.01). Likewise, significant positive correlation was recorded with metals concentration in plants and lake ambient, which further indicated the potential of aforesaid set of wetland macrophytes for pollution monitoring.     

Distribution of Metals in the Edible Plants Grown at Jajmau, Kanpur (India) Receiving Treated Tannery Wastewater: Relation with Physico-Chemical Properties of the Soil

The implications of metal contamination of agricultural soils due to long term irrigation with treated industrial wastewater and their subsequent accumulation in the vegetables/crops growing on such soils has been assessed in an area of industrial complex, Jajmau, Kanpur (India). Physico-chemical properties of the soil were also studied. The soil and vegetables/crops were sampled from an area of 2100 acre agricultural land and analyzed for physico-chemical properties and metal accumulation in different parts of the plants. The comparison of the data of physico-chemical properties of control and contaminated soil showed that salinity, electrical conductivity, available phosphorous, sodium and potassium content (both water soluble and exchangeable) were found high in contaminated soil. The analysis of plant available metal content in the soil showed the highest level of Fe, which ranged from 529.02 to 2615 μg g⁻¹ dw and lowest level of Ni (3.12 to 10.51 μg g⁻¹ dw). The analysis of the results revealed that accumulation of toxic metal Cr in leafy vegetables was found more than fruit bearing vegetables/crops. Thus, it is recommended that the leafy vegetables are unsuitable to grow in such contaminated sites. It is important to note that toxic metal, Ni was not detected in all the plants. The edible part of the vegetables (under ground) such as, garlic (19.27 μg g⁻¹ dw), potato (11.81 μg g⁻¹ dw) and turmeric (20.86 μg g⁻¹ dw) has accumulated lowest level of toxic metal, Cr than leafy and fruit bearing vegetables. In some fruit part of vegetables such as, bitter gourd, egg plant, jack tree, maize and okra, the accumulation of Cr was not detected and may be grown in this area.     

Cadmium adsorption and desorption behaviour on goethite at low equilibrium concentrations: effects of pH and index cations

The transport and bioavailability of cadmium is governed mainly by its adsorption-desorption reactions with minerals such as goethite--a common iron oxide mineral in variable charged and highly weathered tropical soils. Soil factors such as pH, temperature, solution Cd concentration, ionic strength and ageing affect Cd adsorption on goethite. The desorption behaviour of Cd from goethite at low concentrations is not fully understood. This study investigates the adsorption-desorption of Cd at low Cd concentrations (Cd adsorbed on goethite from 20 to 300 microM Cd solutions) in Na and Ca nitrate solutions of 0.03 M nominal ionic strengths. Synthetic goethite prepared by ageing a ferric hydroxide gel at high pH and room temperature was used for Cd adsorption and desorption studies. For desorption experiment 10 successive desorptions were made for the whole range of initial Cd concentrations (20-300 microM) in the presence of 0.01 M Ca(NO3)2 or 0.03 M NaNO3 solutions. Cadmium adsorption was found to be higher in Na+ than Ca2+ probably due to the competition of Ca2+ ions with Cd2+ ions for adsorption sites on the surfaces of goethite. The effect of index cation on Cd adsorption diminished with increase in pH from 5.0 to 6.0. Cadmium desorption decreased with increase in pH from 5.0 to 6.0 in both Na and Ca systems. After 10 successive desorptions with 0.03 M NaNO3 at the lowest initially adsorbed Cd approximately 45%, 20% and 7% of the adsorbed Cd was desorbed at pH 5.0, 5.5 and 6.0, respectively. The corresponding desorptions in the presence of 0.01 M Ca(NO3)2 were 49%, 22% and 8%, respectively. The Freundlich parameter, k, based on each progressive step of desorption at different adsorbed concentration increased with increasing desorption step, which may indicates that a fraction of Cd was resistant to desorption. Low Cd desorbability from goethite may be due to its specific adsorption and/or possibly as a result of Cd entrapment in the cracks or defects in goethite structure.     

Effect of cadmium on growth, ultramorphology of leaf and secondary metabolites of Phyllanthus amarus Schum. and Thonn

The pollution is increasing in the environment by different kinds of human activities, which results in the accumulation of heavy metals including cadmium in the soil and water and it causes different types of problems to living beings. As the plants are utilized by human being as food and medicine, therefore, it is mandatory to see the effect of metals on plants. In this context, efforts have been made to observe the effect of different concentration of Cadmium (Cd) on Phyllanthus amarus Schum. and Thonn., because Cd is the widespread metal and the plants response to low and high level of exposure is a complex phenomenon. P. amarus is mostly grown as weed in agricultural and waste lands. It is a reputed plant used in Indian indigenous systems of medicine with hepatoprotective, diuretic, stomachic properties and is recently being used for the treatment of hepatitis B. The study revealed that Cd causes significant decrease in fresh and dry weight, length of root and shoot, protein, chlorophyll, carotenoids and sugar and increase in starch content. It is interesting to note that the therapeutically active compounds—phyllanthin and hypophyllanthin, enhanced at certain levels of Cd due to abiotic stress. Besides, the ultramorpholical changes were also observed in stomatal opening and wax deposition on both the surfaces of leaves.     

Atrazine and simazine degradation in Pennisetum rhizosphere

The ability of rhizosphere of four plant species to promote the degradation of charcoal-fixed atrazine and simazine in cement blocks of a long-term contaminated soil when mixed with a normal soil at 1:1 ratio was tested. Of the four selected plants viz., rye grass (Lolium perenne), tall fescue (Festuca arundinacae), Pennisetum (Pennisetum clandestinum) and a spring onion (Allium sp.) used in this study, only P. clandestinum was able to survive in herbicide contaminated soil while other plants died within few days after germination/transplanting. Both atrazine and simazine were degraded at a faster rate in contaminated soil planted to P. clandestinum than in unplanted soil. Within 80 days, nearly 45% and 52% of atrazine and simazine, respectively, were degraded in soil planted to P. clandestinum while only 22% and 20% of the respective herbicide were degraded in the unplanted soil. During 80-day experimental period, both microbial biomass and soil dehydrogenase activity were significantly increased (7-fold) in soil planted to P. clandestinum over that in unplanted soil. The suspension of contaminated rhizosphere soil, planted to P. clandestinum exhibited an exceptional capability to degrade both atrazine (300 microg) and simazine (50 microg) in a mineral salts medium over that of non-rhizosphere soil suspension. Results indicate that P. clandestinum, a C4 plant, may be useful for remediation of soils contaminated with atrazine and simazine.     

Effect of lead on growth and nitrate assimilation of Vigna radiata (L.) Wilczek seedlings in a salt affected environment

The inhibition of seedling growth and nitrate reductase activity in 5 d old Vigna radiata (L.) Wilczek cv. Pusa Baisakhi in the presence of 1.0 mM lead acetate increased drastically, if NaCl (6 and 12 EC) was also present in the nutrient media along with the metal salt. Correspondingly higher endogenous Na+ levels were accumulated in the roots and leaves of seedlings in presence of the two stresses. On the other hand, the levels of endogenous lead get reduced in presence of NaCl in both the roots and leaves. Roots accumulated more Pb2+ and Na+ than the leaves. The two stresses affect more drastically in the additive or even synergistic manner during the early growth phase of the seedlings.