Slash and burn agriculture at higher elevations in North-Eastern India. I. Sediment,water and nutrient losses

The hydrology and the pattern of sediment and nutrient loss through water that may occur under ‘slash and burn’ agriculture (jhum) at the time of cropping, as well as during the subsequent fallow development, was studied at higher elevations of Meghalaya, north-eastern India and compared with terrace cultivation. A comparison of an agro-ecosystem under a 10-year jhum cycle with that under a 5-year cycle suggests that the loss of sediment, water and nutrients such as nitrogen and phosphorus is greater under the latter, though cationic losses show a reverse trend. All losses were markedly reduced during fallow development during secondary succession. Terrace cultivation resulted in a general reduction of water and nutrient loss. However, these losses increased during the second year of terrace cultivation.While jhum cannot be sustained with the shorter cycle introduced in recent times, terracing does not seem to offer an alternative.     

Physicochemical characterization of hydroxyapatite and its application towards removal of nitrate from water

A laboratory study was conducted to investigate the efficiency of hydroxyapatite (HAP) towards removal of nitrate from synthetic nitrate solution. In the present research HAP synthesized from egg-shell was characterized using SEM, XRD, FTIR and TGA–DSC. The removal of nitrate was 96% under neutral conditions, using 0.3 g of adsorbent in 100 mL of nitrate solution having an initial concentration of 100 mg/L. An adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to a linearly transformed Langmuir isotherm with correlation coefficient (R²) > 0.98. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with the Dubinin–Radushkevich isotherm. The process was rapid and equilibrium was established within the first 40 min.     

Physico-chemical assessment of paper mill effluent and its heavy metal remediation using aquatic macrophytes—a case study at JK Paper mill, Rayagada, India

The present investigation aims to assess the phytoremediation potential of six aquatic macrophytes, viz. Eichhornia crassipes, Hydrilla verticillata, Jussiaea repens, Lemna minor, Pistia stratiotes and Trapa natans grown in paper mill effluent of JK Paper mill of Rayagada, Orissa, for remediation of heavy metals. The experiment was designed in pot culture experiments. Assessment of physico-chemical parameters of paper mill effluent showed significant decrease in pH, conductivity, total dissolved solids, total suspended solids, chlorine, sulphur, biological and chemical oxygen demand after growth of macrophytes for 20 days. Phytoremediation ability of these aquatic macrophytic species for copper (Cu) and mercury (Hg) was indicated by assessing the decrease in the levels of heavy metals from effluent water. Maximum reduction (66.5 %) in Hg content of untreated paper mill effluent was observed using L. minor followed by T. natans (64.8 %). L. minor showed highest reduction (71.4 %) of Cu content from effluent water followed by E. crassipes (63.6 %). Phytoextraction potential of L. minor was remarkable for Hg and Cu, and bioaccumulation was evident from bioconcentration factor values, i.e. 0.59 and 0.70, respectively. The present phytoremediation approach was considered more effective than conventional chemical treatment method for removing toxic contaminants from paper mill effluent.     

Chromium accumulation in submerged aquatic plants treated with tannery effluent at Kanpur, India

Aquatic macrophytes have been widely studied because of their capability of absorbing contaminants from water and their subsequent use in biomonitoring. This study presents a comparison of Cr accumulating potential of submerged aquatic plants viz Vallisneria spiralis and Hydrilla verticillata. These plants were treated with various concentrations of treated tannery effluent collected from UASB, Jajmau, Kanpur under repeated exposure in controlled laboratory conditions in order to assess their maximum bioaccumulation potential. The maximum accumulation of 385.6 and 201.6 microg g(-1) dry weight was found in roots of V. spiralis and the whole plants of H. verticillata, respectively at 100% concentration after 9th day of effluent exposure. The chlorophyll and protein content of both species decreased with increase in effluent concentration and duration. At highest concentration and duration a maximum reduction of 67.4 and 62.66% in total chlorophyll content, 9.97 and 4.66% in carotenoid content and 62.66 and 59.36% in protein content was found in V. spiralis and H. verticillata respectively. Anatomical studies in both V. spiralis and H. verticillata was carried out to assess the effects of metal accumulation within the plants. Changes in the anatomical structures of both plants exhibits the capacity of these species to act as indicator of effluent toxicity. The high accumulation potential of Cr by both plants revealed their capability to remove pollutants from effluent.     

Determination of atmospheric heavy metals using two lichen species in Katni and Rewa cities, India

A biomonitoring study was conducted to assess the levels of atmospheric heavy metal pollution in Katni and Rewa cities of Madhya Pradesh, state in central India. The Pyxine cocoes and Phaeophyscia hispidula, two epiphytic foliose lichen were used as bioindicators in the present study and seven metals (As, Al, Cd, Cr, Fe, Zn, Pb) were analyzed in naturally growing thallus. The concentrations of these metals was observed to be in higher range as maximum values of Al, Cd, Cr and Zn were reported from the lichen samples from Rewa city which was 561.8 +/- 2.4, 6.8 +/- 0.8, 35.2 +/- 1.4, 214.6 +/- 2.0 microg g(-1) dry weight respectively. Whereas As, Fe and Pb were reported maximum in the lichen samples collected from Katni city areas with 33.4 +/- 0.05, 689.4 +/- 2.6, 13.3 +/- 0.5 microg g(-1) dry weight respectively. However the accumulation of Cd and Pb from both the cities are more or less similar in concentration. The selectivity sequence of metals were Fe>Al>Zn>As>Cr>Pb>Cd in Katni city, and Al>Fe>Zn>Cr>As>Pb>Cd in Rewa city. The findings of this study indicates that extent of heavy metal pollution in the atmosphere of the two cities which may lead to adverse health affects.     

Concentrations of heavy metals and aquatic macrophytes of Govind Ballabh Pant Sagar an anthropogenic lake affected by coal mining effluent

Five heavy metals Cu, Cd, Mn, Pb and Hg were found in high concentration from three sampling sites located in Asia’s largest anthropogenic lake Govind Ballabh Pant GBP Sagar. Concentrations of these heavy metals were measured in Water, bottom sediment and in different parts of the aquatic macrophytes collected from the reservoir. Plants collected from the lake were Eichhornia crassipes, Azolla pinnata, Lemna minor, Spirodela polyrrhiza, Potamogeton pectinatus, Marsilea quadrifolia, Pistia stratiotes, Ipomea aquqtica, Potamogeton crispus, Hydrilla verticillata and Aponogeton natans. These plants have shown the high concentrations of Cu, Cd, Mn, Pb and Hg in their different parts due to bioaccumulation. In general plant roots exhibited higher concentrations of heavy metals than corresponding sediments. A comparison between different morphological tissues of the sampled plants reveled the metal concentration in following order roots > leaves. Analyses of bottom sediment indicated the higher concentrations of Cd, Mn, Cu and Pb. Strong positive correlations were obtained between the metals in water and in plants as well as between metal in sediment and in plants. Indicating the potential of these plants for pollution monitoring of these metals.     

Decolourization of pulp and paper mill effluents using heat-treated coal: a comparison with activated charcoal

A comparison between activated charcoal and heat-treated coal for decolourization of pulp and paper mill waste water was studied. The heat-treated coal was prepared in an inert atmosphere at 800°C. The adsorption dynamics that include batch contact–time study, kinetics along with adsorption isotherms were carried out. The study shows that heat-treated coal is a suitable adsorbent and can be used for the decolourization of pulp and paper mill effluent streams. The maximum removal was achieved at the initial stages of contact, and the overall adsorption was a slow process. However, the equilibrium concentration in the case of both the adsorbents reaches at almost same time. The linear plot of the Lagergren model shows its applicability and first-order kinetics.     

Influence of ferrochrome ash on mechanical and microstructure properties of ambient cured fly ash-based geopolymer concrete

Journal of Material Cycles and Waste Management - Earlier studies indicated that the reactive MgO reduces shrinkage crack and porosity, and accelerates the hydration and strength development....     

Impact of climate change on agricultural production of Odisha (India): a Ricardian analysis

Regional Environmental Change - The present study examines the climate sensitivity of the agricultural production of Odisha, a state at the east coast of India. The two climatic variables which...     

Utilization of fly ash in adsorption of heavy metals from wastewater

The aim of this study was to assess the toxicity reduction of wastewaster after treatment with fly ash. Fly ash is a waste material which is formed as a result of coal burning in power plants, but has the potential to adsorb heavy metal ions. The present study examined the adsorption capacity of fly ash to adsorb Pb²⁺, Cu²⁺, and Zn²⁺ from waste water under different conditions of contact time, pH, and temperature. Uptake of metal ions by fly ash generally rose with increasing pH. At lower temperatures the uptake of heavy metal adsorption were enhanced. Significant reduction in Pb²⁺ (79%), Cu²⁺ (53%), and Zn²⁺ (80%) content was found after treatment with fly ash of waste water treatment. Using the microtox test toxicity of the effluent was reduced by 75% due to removal of Pb²⁺ ion by the fly ash. Data indicated that fly ash generated by power plants may be used beneficially to remove metals from waste water.