Performance evaluation of isoproturon-degrading indigenous bacterial isolates in soil microcosm

Isoproturon (IPU)-degrading soil bacteria were isolated from herbicide-applied wheat fields. These isolates were identified using cultural, morphological, biochemical and 16S rRNA sequencing methods. 16S rRNA sequences of both the bacterial isolates were compared with NCBI GenBank data base and identified as Bacillus pumilus and Pseudoxanthomonas sp. A soil microcosm study was carried out for 40 days in six different treatments. Experimental results revealed maximum 95.98% IPU degradation in treatment 6 where bacterial consortia were augmented in natural soil, followed by 91.53% in treatment 5 enriched with organic manure as an additional carbon source. However, only 14.03% IPU was degraded in treatment 1 (control) after 40 days. In treatments (2–4), 75.59%, 70.92% and 77.32% IPU degradation was recorded, respectively. IPU degradation in all the treatments varied significantly over the control. 4-Isopropylaniline was detected as IPU degradation by-product in the medium. The study confirmed that B. pumilus and Pseudoxanthomonas sp. performed effectively in soil microcosms and could be employed profitably for field-scale bioremediation experiments.     

Biodegradation of pulp and paper mill effluent by co-culturing ascomycetous fungi in repeated batch process

The competence of novel fungal consortium, consisting of Nigrospora sp. LDF00204 (accession no. KP732542) and Curvularia lunata LDF21 (accession no. KU664593), was investigated for the treatment of pulp and paper mill effluent. Fungal consortium exhibited enhanced biomass production under optimized medium conditions, i.e., glucose as carbon (C), sodium nitrate as nitrogen (N), C/N 1.5:0.5, pH 5, temperature 30 °C, and agitation 140 rpm, and significantly reduced biochemical oxygen demand (85.6%), chemical oxygen demand (80%), color (82.3%), and lignin concentration (76.1%) under catalytic enzyme activity; however, unutilized ligninolytic enzymes, such as laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP), were observed to be 13.5, 11.4, and 9.4 U/ml after the third cycle of effluent treatment in repeated batch process. Scanning electron microscopy (SEM) of fungal consortium revealed their compatibility through intermingled hyphae and spores, while the FTIR spectra confirmed the alteration of functional groups ensuring structural changes during the effluent treatment. Gas chromatography/mass spectroscopy (GC-MS) analysis showed the reduction of complex compounds and development of numerous low-molecular-weight metabolites, such as 1-3-dimethyl benzene, 2-chloro-3-methyl butane, pentadecanoic acid, and 1-2-benzene dicarboxylic acid, during the treatment, demonstrating the massive potential of the novel fungal consortium to degrade recalcitrant industrial pollutants.     

Composition, seasonal variation, and sources of PM10 from world heritage site Taj Mahal, Agra

Air samples for PM(10) (dp?相似文献   

Differential sorption behaviour of aromatic hydrocarbons on charcoals prepared at different temperatures from grass and wood

Naturally occurring charcoals are increasingly being recognized as effective sorbents for organic compounds. In this study we investigated the sorption of benzene and toluene in single-sorbate and bi-sorbate systems on different types of charcoals produced in laboratory, employing the batch sorption technique. Air dried plant materials from Phalaris grass (Phalaris tuberosa) and Red Gum wood (Eucalyptus camadulensis) were combusted under limited oxygen supply at 250 degrees C, 450 degrees C, and 850 degrees C. The resulting charcoals were characterized for their specific surface areas, total cation content, and pore size distributions (pore size distribution only for wood combusted at 450 degrees C and 850 degrees C). For the materials treated at 850 degrees C not only the surface area, microporosity, and total amount of sorbed sorbate increased markedly, but also the non-linearity of the sorption isotherm. The pore size distributions and surface areas as well as an indifferent sorption behaviour and competition effects for both sorbates indicated that pore filling mechanisms were the dominating processes governing the sorption on these microporous, high temperature treated materials. For the materials treated at lower temperatures the affinity of toluene was higher compared to that of benzene. In the bi-sorbate system the overall uptake of benzene increased. These phenomena might be due to the stronger hydrophobicity of toluene, and to a varying potential for swelling of the matrix and pore deformation by the two sorbates. The significantly lower sorption capacity of the Phalaris-derived material compared to the Red Gum charcoal correlated with its smaller surface area and higher cation content.     

Integration of the Pesticide Impact Rating Index with a Geographic Information System for the Assessment of Pesticide Impact on Water Quality

The pesticide impact rating index (PIRI) has been integrated with a Geographic Information System (GIS) to enable regional assessment of pesticide impact on groundwater and surface water resources. The GIS version of PIRI (PIRI-GIS) was used to assess the impact of pre-planting atrazine use in the pine plantations on the Gnangara Mound, Western Australia. The impact on groundwater was found to be spatially variable, mainly dependent on soil type and depth to groundwater, because land use variables were spatially constant. Areas with the greatest impact on groundwater were those where the soil had a low sorption capacity for atrazine. Knowledge of the spatial distribution of the sorption coefficient based on organic carbon (K _oc) for atrazine was found to significantly improve the results from PIRI-GIS. Average values for K _oc (i.e. based on overseas data) were too low for most of the local soil types, resulting in a general overestimation of pesticide impact on groundwater resources, but an underestimation of impact in areas that should be of greatest concern (i.e. where the soil has a low sorption capacity for atrazine).     

Abiotic degradation (photodegradation and hydrolysis) of imidazolinone herbicides

The abiotic degradation of the imidazolinone herbicides imazapyr, imazethapyr and imazaquin was investigated under controlled conditions. Hydrolysis, where it occurred, and photodegradation both followed first-order kinetics for all herbicides. There was no hydrolysis of any of the herbicides in buffer solutions at pH 3 or pH 7; however, slow hydrolysis occurred at pH 9. Estimated half-lives for the three herbicides in solution in the dark were 6.5, 9.2 and 9.6 months for imazaquin, imazethapyr and imazapyr, respectively. Degradation of the herbicides in the light was considerably more rapid than in the dark with half lives for the three herbicides of 1.8, 9.8 and 9.1 days for imazaquin, imazethapyr and imazapyr, respectively. The presence of humic acids in the solution reduced the rate of photodegradation for all three herbicides, with higher concentrations of humic acids generally having greater effect. Photodegradation of imazethapyr was the least sensitive to humic acids. The enantioselectivity of photodegradation was investigated using imazaquin, with photodegradation occurring at the same rate for both enantiomers. Abiotic degradation of imidazolinone herbicides on the soil surface only occurred in the presence of light. The rate of degradation for all herbicides was slower than in solution, with half-lives of 15.3, 24.6 and 30.9 days for imazaquin, imazethapyr and imazapyr, respectively. Abiotic degradation of these herbicides is likely to be slow in the environment and is only likely to occur in clear water or on the soil surface.     

Biological degradation of triclocarban and triclosan in a soil under aerobic and anaerobic conditions and comparison with environmental fate modelling

Triclocarban and triclosan are two antimicrobial agents widely used in many personal care products. Their biodegradation behaviour in soil was investigated by laboratory degradation experiments and environmental fate modelling. Quantitative structure-activity relationship (QSAR) analyses showed that triclocarban and triclosan had a tendency to partition into soil or sediment in the environment. Fate modelling suggests that either triclocarban or triclosan "does not degrade fast" with its primary biodegradation half-life of "weeks" and ultimate biodegradation half-life of "months". Laboratory experiments showed that triclocarban and triclosan were degraded in the aerobic soil with half-life of 108 days and 18 days, respectively. No negative effect of these two antimicrobial agents on soil microbial activity was observed in the aerobic soil samples during the experiments. But these two compounds persisted in the anaerobic soil within 70 days of the experimental period.     

Assessment of yield losses in tropical wheat using open top chambers

The present study deals with the evaluation of effects of ambient gaseous air pollution on wheat (Triticum aestivum L. var. HUW-234) growing in a suburban area situated in eastern Gangetic plain of India, using open top chambers. Eight hourly air monitoring was conducted for ambient concentrations of SO₂, NO₂ and O₃ in filtered chambers (FCs), non-filtered chambers (NFCs) and open plots (OPs). Various morphological, physiological and biochemical parameters were assessed during different developmental stages and finally yield parameters were quantified at the time of harvest.Mean concentrations of SO₂, NO₂ and O₃ were 8.4, 39.9 and 40.1 ppb, respectively during the experiment in NFCs. Concentrations of SO₂, NO₂ and O₃ reduced by 74.6%, 84.7% and 90.4%, respectively in FCs as compared to NFCs. Plants grown in FCs showed higher photosynthetic rate, stomatal conductance, chlorophyll content and Fv/Fm ratio as compared to the plants in NFCs and OPs. Lipid peroxidation, proline, total phenol and ascorbic acid contents and peroxidase activity were higher in plants grown in NFCs. There were improvements in morphological parameters of plants growing in FCs as compared to those in NFCs and OPs. Yield of plants also increased significantly in FCs as compared to those ventilated with ambient air (NFCs) or grown in OPs. During the vegetative phase, NO₂ concentrations were higher than O₃, but O₃ became dominant pollutant during the time of grain setting and filling. The study concludes that O₃ and NO₂ are the main air pollutants in the sub-urban areas causing significant yield reductions in tropical wheat plants.