Chemical Approach to Study the Environmental Implications of Humic Acid and Gamma-Hch Interaction

Pesticide-humic interactions are known to have environmental significance in modifying the toxicity and mobility of agricultural chemicals. to test this, interaction between gamma-hexachlorocyclohexane (gamma-HCH) released from the sand coated with gamma-HCH and humic acid was investigated using thin layer chromatography and spectral studies such as UV (ultraviolet), IR (infrared), mass and FAB (fast atom bombardment) mass spectrometry. These studies revealed the evidence of loose interchelation between gamma-HCH and humic acid. the significance of the results in relation to detoxification of gamma-HCH in aquatic ecosystems are discussed.     

Comparative study on the effect of chemicals on Alternaria blight in Indian mustard--a multi-location study in India

High severity of Altemaria blight disease is a major constraint in production of rapeseed-mustard in India. The aim of this study was to investigate the suppressive potential of chemicals viz., zinc sulphate, borax, sulphur, potash and calcium sulphate, aqueous extracts viz., Eucalyptus globosus (50 g l-1) leaf extract and garlic (Allium sativum) bulb (20 g l-1) extract, cow urine and bio-agents Trichoderma harzianum, Pseudomonas fluorescence in comparison with the recommended chemical fungicide (mancozeb), against foliar disease Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. and Coss] under five different geographical locations of India. Mancozeb recorded the lowest mean severity (leaf: 33.1%; pod: 26.3%) of Alternaria blight with efficacy of garlic bulb extract alone (leaf = 34.4%; pod = 27.3%) or in combination with cow urine (leaf = 34.2%; pod = 28.6%) being statistically at par with the recommended chemical fungicide. Chemicals also proved effective in reducing Alternaria blight severity on leaves and pods of Indian mustard (leaf = 36.3-37.9%; pod = 27.5-30.1%). The effective treatments besides providing significant reduction in disease severity also enabled increase in dry seed yield of the crop (mancozeb = 2052 kg ha-1; garlic = 2006 kg ha-1; control = 1561 kg ha-1).     

Catalytic oxidative treatment of diluted black liquor at mild conditions using copper oxide/cerium oxide catalyst.

Wet-air oxidation of diluted black liquor (chemical oxygen demand [COD] approximately 3250 to 14 500 mg/L) was performed at mild operating conditions (temperature = 388 to 423 K and total pressure = 0.6 MPa) in the presence of heterogeneous 60% copper oxide (CuO)/ 40% cerium oxide (CeO2) catalyst. Maximum COD reduction of 77.3% was obtained at 423 K at pH 3.0, which was marginally higher than that obtained at 413 K temperature (77.1%). In the acidic environment (pH < or = 3), most of the COD was removed in the form of settleable solids during the transient heating of the wastewater from room temperature to the desired one. The solid residue obtained after the reaction has a heating value of 20.1 MJ/kg, which is comparable with that of Indian coal. Thermal degradation kinetic determination suggested that thermal characteristics of the solid residue are well represented by a power law model with Agarwal and Sivasubramanian approximation (Safi et al., 2004).     

Crystalline hydrous ferric oxide: an adsorbent for chromium(VI)-contaminated industrial wastewater treatment.

Synthetic crystalline hydrous ferric oxide (CHFO) (particle size 0.14 to 0.29 mm) has been used systematically for adsorptive chromium(VI) removal from contaminated water. Batch experiments were performed as a function of pH, contact time, solute concentration, and regeneration of adsorbents. Column experiments were performed for breakthrough points in the presence and absence of other ions and treatment of industrial effluent. The optimum pH range was 2.0 to 4.0. The adsorption kinetic data could be described well by both second-order and pseudo-first-order models. The isotherm adsorption data at 30 +/- 2 degrees C obeyed the Langmuir model best. The monolayer adsorption capacity was 35.7 mg/g. Chromium(VI)-rich CHFO could be regenerated up to 89 +/- 1% with 2.0 M sodium hydroxide. Regenerated column reuse showed a decrease (10 to 12%) in breakthrough capacity. Finally, the CHFO- (dried at 300 degrees C) packed column was used for the recovery (98.5 +/- 1.0%) of chromium(VI) from contaminated industrial waste effluent of Hindustan Motor Limited (Hooghly, West Bengal, India).     

Studies on mycorrhizal inoculation on dry matter yield and root colonization of some medicinal plants grown in stress and forest soils

Five medicinal plants viz. Abelmoschatus moschatus Linn., Clitoria tematea L., Plumbagozeylanica L., Psorolea corylifolia L. and Withania sominifera L. were grown in a polypot experiment in five soils representing coal mine soil, coppermine soil, fly ash, skeletal soil and forest soil with and without mycorrhizal inoculations in a completely randomized block design. Dry matter yield and mycorrhizal root colonization of plants varied both in uninoculated and inoculated conditions. The forest soil rendered highest dry matter due to higher yield of A. moschatus, P. zeylanica and P corylifolia while fly ash showed lowest dry matter without any inoculants. P. cematea were best in coalmine soil and W. sominifera in copper mine soil without mycorrhizal inoculation. The mycorrhiza was found to enhance the dry matter yield. This contributed minimum 0.19% to maximum up to 422.0% in different soils as compared to uninoculated plants. The mycorrhizal dependency was noticed maximum in plants grown in fly ash followed by coal mine soil, copper mine soil, skeletal soil and forest soil. The mycorrhizal response was increased maximum in W. sominifera due to survival in fly ash after inoculation followed by P corylifolia and P cematea. Percent root colonization in inoculated plant was increased minimum of 1.10 fold to maximum of 12.0 folds in comparison to un-inoculated plants . The native mycorrhiza fungi were also observed to colonize 4.0 to 32.0% roots in plants understudy. This study suggests that mycorrhizal inoculation increased the dry matter yield of medicinal plants in all soils under study. It also helps in survival of W. sominifera in fly ash.     

Arsenic tolerances in rice (Oryza sativa) have a predominant role in transcriptional regulation of a set of genes including sulphur assimilation pathway and antioxidant system

World wide arsenic (As) contamination of rice has raised much concern as it is the staple crop for millions. Four most commonly cultivated rice cultivars, Triguna, IR-36, PNR-519 and IET-4786, of the West Bengal region were taken for a hydroponic study to examine the effect of arsenate (As^V) and arsenite (As^III) on growth response, expression of genes and antioxidants vis-à-vis As accumulation. The rice genotypes responded differentially under As^V and As^III stress in terms of gene expression and antioxidant defences. Some of the transporters were up-regulated in all rice cultivars at lower doses of As species, except IET-4786. Phytochelatin synthase, GST and γ-ECS showed considerable variation in their expression pattern in all genotypes, however in IET-4786 they were generally down-regulated in higher As^III stress. Similarly, most of antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) increased significantly in Triguna, IR-36 and PNR-519 and decreased in IET-4786. Our study suggests that Triguna, IR-36 and PNR-519 are tolerant rice cultivars accumulating higher arsenic; however IET-4786 is susceptible to As-stress and accumulates less arsenic than other cultivars.