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931.
Sharma KK Kalpana Sharma V Gupta P Jaya M Kumar A Singh B 《Environmental monitoring and assessment》2008,137(1-3):179-184
Fipronil termiticide belongs to phenyl-pyrazole class of chemical compounds. It has broad-spectrum activity particularly against
house hold pests such as cockroaches, mosquitoes, locusts, ticks, and fleas at both larval and adult stages. At high dosage
it can be used to control subterranean termites in building foundations. To evaluate long term efficacy against termites the
persistence and vertical distribution of fipronil was studied under natural weather conditions of Dehradun, India. Fipronil
was applied at four concentrations i.e. 0.05, 0.1, 0.25 and 0.5% a.i ha−1 by drenching 17 × 17 in.2 plot prepared as per modified ground board test. Soil samples were collected after 22, 38 and 56 months of treatment up to
the depth of 75 cm. The soil core was cut into five distinct sections i.e. 0–15, 15–30, 30–45, 45–60 and 60–75 cm depth. The
residues were extracted by shaking 20 g soil sample with acetone. The acetone extract was concentrated and cleaned-up over
florisil column. Fipronil residues were estimated on GLC at 220, 260, and 300°C oven, injector and detector temperature respectively.
Fipronil was found to persist beyond 56 months after application. Two metabolites viz. desulfinyl and sulfide-fipronil were
detected in sampling after 22 months of application that also dissipated with time. Fipronil residues were found up to 60 cm
depth. The residues in deeper layers dissipate slowly with time and after 56 months of treatment residues were detected only
up to 30 cm depth. 相似文献
932.
M. Berlin G. Suresh Kumar Indumathi M. Nambi 《Environmental Modeling and Assessment》2014,19(4):283-299
Nitrogen pollution in groundwater resulting from wastewater application to land is a common problem, and it causes a major threat to groundwater-based drinking water supplies. In this study, a numerical model is developed to study the nitrogen species transport and transformation in unsaturated porous media. Further, a new mass transfer module for dissolved oxygen (DO) is incorporated in the one-dimensional numerical model for nitrogen species transport to describe the fate and transport of nitrogen species, dissolved oxygen, dissolved organic carbon (DOC), and biomass. The spatial and temporal variation of dissolved oxygen is incorporated in the model through the mass transfer from gaseous phase to water phase in an unsaturated porous system. The numerical results of the water flow model and single species and multispecies transport model in an unsaturated zone developed for this purpose have been validated with the available analytical/numerical solution. The developed model is applied in clay loam, silt, and sand soils to analyze the transport behavior of nitrogen species under unsaturated condition. The numerical results suggest that the high rate of oxygen mass transfer from the air phase to the water phase positively increases the dissolved oxygen in the applied wastewater and enhances the nitrification process. Because of this high oxygen mass transfer, the nitrate nitrogen concentration significantly increases in the unsaturated zone and the same is transported to a larger depth at higher simulation period. On the other hand, the low rate of oxygen mass transfer implicitly enhances the denitrification process and finally reduces the nitrate nitrogen concentration in the unsaturated zone. The numerical results also show that the nitrate nitrogen transport is rapid in sandy soil when compared with clay loam and silty soils under high oxygen mass transfer rate. In essence, the high oxygen mass transfer rate significantly increases the nitrate nitrogen in the unsaturated zone, especially at a greater depth at larger time levels and eventually affects the groundwater quality. 相似文献
933.
Mapping aboveground woody biomass using forest inventory,remote sensing and geostatistical techniques 总被引:1,自引:0,他引:1
Mapping forest biomass is fundamental for estimating CO2 emissions, and planning and monitoring of forests and ecosystem productivity. The present study attempted to map aboveground woody biomass (AGWB) integrating forest inventory, remote sensing and geostatistical techniques, viz., direct radiometric relationships (DRR), k-nearest neighbours (k-NN) and cokriging (CoK) and to evaluate their accuracy. A part of the Timli Forest Range of Kalsi Soil and Water Conservation Division, Uttarakhand, India was selected for the present study. Stratified random sampling was used to collect biophysical data from 36 sample plots of 0.1 ha (31.62 m?×?31.62 m) size. Species-specific volumetric equations were used for calculating volume and multiplied by specific gravity to get biomass. Three forest-type density classes, viz. 10–40, 40–70 and >70 % of Shorea robusta forest and four non-forest classes were delineated using on-screen visual interpretation of IRS P6 LISS-III data of December 2012. The volume in different strata of forest-type density ranged from 189.84 to 484.36 m3 ha?1. The total growing stock of the forest was found to be 2,024,652.88 m3. The AGWB ranged from 143 to 421 Mgha?1. Spectral bands and vegetation indices were used as independent variables and biomass as dependent variable for DRR, k-NN and CoK. After validation and comparison, k-NN method of Mahalanobis distance (root mean square error (RMSE)?=?42.25 Mgha?1) was found to be the best method followed by fuzzy distance and Euclidean distance with RMSE of 44.23 and 45.13 Mgha?1 respectively. DRR was found to be the least accurate method with RMSE of 67.17 Mgha?1. The study highlighted the potential of integrating of forest inventory, remote sensing and geostatistical techniques for forest biomass mapping. 相似文献
934.
Priyanka Chaudhary Harmesh Sahay Richa Sharma Alok Kumar Pandey Shashi Bala Singh A. K. Saxena Lata Nain 《Environmental monitoring and assessment》2015,187(6):391
Polyaromatic hydrocarbons (PAHs) utilizing bacteria were isolated from soils of seven sites of Mathura refinery, India. Twenty-six bacterial strains with different morphotypes were isolated. These strains were acclimatized to utilize a mixture of four polycyclic aromatic hydrocarbons, i.e., anthracene, fluorene, phenanthrene, and pyrene, each at 50 mg/L concentration as sole carbon source. Out of total isolates, 15 potent isolates were subjected to 16S rDNA sequencing and identified as a member of diverse genera, i.e., Bacillus, Acinetobacter, Stenotrophomonas, Alcaligenes, Lysinibacillus, Brevibacterium, Serratia, and Streptomyces. Consortium of four promising isolates (Acinetobacter, Brevibacterium, Serratia, and Streptomyces) were also investigated for bioremediation of PAH mixture. This consortium was proved to be efficient PAH degrader resulting in 40–70 % degradation of PAH within 7 days. Results of this study indicated that these genera may play an active role in bioremediation of PAHs. 相似文献
935.
Enteric methane mitigation technologies for ruminant livestock: a synthesis of current research and future directions 总被引:2,自引:0,他引:2
Patra AK 《Environmental monitoring and assessment》2012,184(4):1929-1952
Enteric methane (CH4) emission in ruminants, which is produced via fermentation of feeds in the rumen and lower digestive tract by methanogenic
archaea, represents a loss of 2% to 12% of gross energy of feeds and contributes to global greenhouse effects. Globally, about
80 million tonnes of CH4 is produced annually from enteric fermentation mainly from ruminants. Therefore, CH4 mitigation strategies in ruminants have focused to obtain economic as well as environmental benefits. Some mitigation options
such as chemical inhibitors, defaunation, and ionophores inhibit methanogenesis directly or indirectly in the rumen, but they
have not confirmed consistent effects for practical use. A variety of nutritional amendments such as increasing the amount
of grains, inclusion of some leguminous forages containing condensed tannins and ionophore compounds in diets, supplementation
of low-quality roughages with protein and readily fermentable carbohydrates, and addition of fats show promise for CH4 mitigation. These nutritional amendments also increase the efficiency of feed utilization and, therefore, are most likely
to be adopted by farmers. Several new potential technologies such as use of plant secondary metabolites, probiotics and propionate
enhancers, stimulation of acetogens, immunization, CH4 oxidation by methylotrophs, and genetic selection of low CH4-producing animals have emerged to decrease CH4 production, but these require extensive research before they can be recommended to livestock producers. The use of bacteriocins,
bacteriophages, and development of recombinant vaccines targeting archaeal-specific genes and cell surface proteins may be
areas worthy of investigation for CH4 mitigation as well. A combination of different CH4 mitigation strategies should be adopted in farm levels to substantially decrease methane emission from ruminants. Evidently,
comprehensive research is needed to explore proven and reliable CH4 mitigation technologies that would be practically feasible and economically viable while improving ruminant production. 相似文献
936.
Peitzsch M Sulyok M Täubel M Vishwanath V Krop E Borràs-Santos A Hyvärinen A Nevalainen A Krska R Larsson L 《Journal of environmental monitoring : JEM》2012,14(8):2044-2053
Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses. 相似文献
937.
Aminul Islam Noushi Zaidi Hilal Ahmad Sudesh Yadav 《Environmental monitoring and assessment》2014,186(9):5843-5853
A procedure is detailed for the selective analysis of trace aluminum by flame atomic absorption spectrophotometer coupled with off-line column separation and preconcentration. Chelating resin was synthesized by covalent functionalization of Amberlite XAD-16 by 2-(2-hydroxyphenyl) benzoxazole. The modified resin was characterized using FT-IR spectroscopy, energy dispersive x-ray analysis, elemental analysis, thermogravimetric analysis/differential thermal analysis, and minimum energy run. The optimum sorption was at pH 9?±?0.1 with corresponding t 1/2 of only 7 min. Many competitive anions and cations studied did not interfere at all in the selective determination of Al(III), at the optimized conditions. The resin shows maximum sorption capacity of 21.58 mg g?1 and can be regenerated up to 75 cycles without any discernible capacity loss. The Langmuir isotherm model provides the better correlation of the experimental data (r 2?=?0.999) in comparison to Freundlich isotherm model, while the Scatchard analysis revealed homogeneous binding sites in the chelating resin. Analytical figures of merit were evaluated by accuracy (standard reference materials and recovery experiment), precision (RSD <5 %), and detection limit (2.8 μg L?1). The applicability was demonstrated by analysis of trace aluminum in biological, environmental, and food samples. 相似文献
938.
Spatial variability and temporal changes in the trace metal content of soils: implications for mine restoration plan 总被引:1,自引:0,他引:1
Rachna Chandra B. Anjan Kumar Prusty P. A. Azeez 《Environmental monitoring and assessment》2014,186(6):3661-3671
Trace metals in soils may be inherited from the parent materials or added to the system due to anthropogenic activities. In proposed mining areas, trace metals become an integral part of the soil system. Usually, researchers undertake experiments on plant species selection (for the restoration plan) only after the termination of mining activities, i.e. without any pre-mining information about the soil-plant interactions. Though not shown in studies, it is clear that several recovery plans remain unsuccessful while carrying out restoration experiments. Therefore, we hypothesize that to restore the area effectively, it is imperative to consider the pre-mining scenario of metal levels in parent material as well as the vegetation ecology of the region. With these specifics, we examined the concentrations of trace metals in parent soils at three proposed bauxite locations in the Eastern Ghats, India, and compared them at a spatio-temporal scale. Vegetation quantification and other basic soil parameters accounted for establishing the connection between soil and plants. The study recorded significant spatial heterogeneity in trace metal concentrations and the role of vegetation on metal availability. Oxidation reduction potential (ORP), pH and cation exchange capacity (CEC) directly influenced metal content, and Cu and Ni were lithogenic in origin. It implies that for effective restoration plant species varies for each geological location. 相似文献
939.
Ground level ozone is responsible for the formation ofsmog, and for a variety of adverse effects on bothhuman and plant life. High concentrations of groundlevel ozone occur during the summer months. This paperdescribes the development of a model to forecast themaximum daily concentration of ozone as a function ofthe maximum surface temperature, for ozonenon-attainment regions in Ohio. The model wasdeveloped by statistical analysis of existing data.Site-specific models were developed initially. Theverification and evaluation of the performancecriteria of the model at each site were explored bycomparing the model with an independent datasetcollected from that site. A generalized statewidemodel was developed from the site-specific models. Theperformance criteria of this model were verified andevaluated by employing the same independent datasetsemployed for the site-specific models. An exceedencemodel to predict the occurrence of ozone exceedencesover 100 ppb has also been presented. 相似文献
940.