We assessed the potential of fluoride (F) contamination in drinking groundwater of an intensively cultivated district in India as a function of its lithology and agricultural activities. Three hundred and eight groundwater samples were collected at different depths from various types of wells and analyzed for pH, EC, NO(3)-N load and F content. A typical litholog was constructed and database on fertilizer and pesticide uses were also recorded for the district. The water samples were almost neutral in reaction and non-saline in nature with low NO(3)-N content (0.02 to 4.56 microg mL(-1)). Fluoride content in water was also low (0.01 to 1.18 microg mL(-1)) with only 2.27% of them exceeding 1.0 microg mL(-1) posing a potential threat of fluorosis. On average, its content varied little spatially and along depth of sampling aquifers because of homogeneity in lithology of the district. The F content in these samples showed a significant positive correlation (r = 0.12, P < or = 0.05) with the amount of phosphatic fertilizer (single super phosphate) used for agriculture but no such relation either with the anthropogenic activities of pesticide use or NO(3)-N content, pH and EC values of the samples was found. The results suggest that the use of phosphatic fertilizer may have some role to play in F enrichment of groundwater. 相似文献
2,4-Dihydroxy-7-methoxy-1,4-benzoxazine-3-one (DIMBOA) known for its antibiotic properties against many pests and diseases in maize plant was extracted from different varieties. In one of the extraction methods of DIMBOA from maize leaves, Amberlite XAD7, an adsorbent, was used for extracting this and it gave a pure fraction containing DIMBOA. The adsorbent Amberlite XAD, being an expensive material, was uneconomical for processing a large number of samples. Therefore, one of the reported solvent extraction method was modified to make the extraction procedure cost effective without losing the target compounds. Using the modified method, DIMBOA was extracted for different varieties under dark and light condition. Results showed that high concentrations of DIMBOA were extracted from plants grown in dark condition as compared to plants grown in light indicating that light played significant role in inhibition of DIMBOA. 相似文献
Endemic fluorosis was detected in 31 villages in the Dhar district of Madhya Pradesh, Central India. Out of the 109 drinking water sources that were analyzed, about 67 % were found to contain high concentration of fluoride above the permissible level of 1.0 mg/l. Dental fluorosis among the primary school children in the age between 8 and 15 served as primary indicator for fluoride intoxication among the children. Urinary fluoride levels among the adults were found to be correlated with drinking water fluoride in 10 villages affected by fluoride. Intervention in the form of alternate safe water supply in five villages showed significant reduction in the urinary fluoride concentration when compared to the control village. Urinary fluoride serves as an excellent marker for assessing the effectiveness of intervention program in the fluoride-affected villages. 相似文献
The sorption and desorption of cadmium and zinc on zeolite 4A, zeolite 13X and bentonite has been studied using batch sorption studies. Parameters such as equilibrium time, effect of pH and sorbent dose were studied. The sorbents exhibited good sorption potential for cadmium and zinc with a peak value at pH 6.0 and 6.5, respectively. The sorption followed the Freundlich sorption model. More than 70% sorption occurred within 20 min and equilibrium was attained at around 90 min for the three sorbents. The metals sorption by zeolite 4A was higher than that by zeolite 13X and bentonite. The desorption studies were carried out using NaCl solution and the effect of NaCl concentration on desorption was also studied. Maximum desorption of 76% for cadmium and 80% for zinc occurred with 10% NaCl. 相似文献
At present, flood is the most significant environmental problem in the entire world. In this work, flood susceptibility (FS) analysis has been done in the Dwarkeswar River basin of Bengal basin, India. Fourteen flood causative factors extracted from different datasets like DEM, satellite images, geology, soil and rainfall data have been considered to predict FS. Three heuristic models and one statistical model fuzzy Logic (FL), frequency ratio (FR), multi-criteria decision analysis (MCDA) and logistic regression (LR) have been used. The validating datasets are used to validate these models. The result shows that 68.71%, 68.7%, 60.56% and 48.51% area of the basin is under the moderate to very high FS by the MCDA, FR, FL and LR, respectively. The ROC curve with AUC analysis has shown that the accuracy level of the LR model (AUC?=?0.916) is very much successful to predict the flood. The rest of the models like FL, MCDA and FR (AUC?=?0.893, 0.857 and 0.835, respectively) have lesser accuracy than the LR model. The elevation was the most dominating factor with coefficient value of 19.078 in preparation of the FS according to the LR model. The outcome of this study can be implemented by local and state authority to minimize the flood hazard.
Oxidation of methanol over V2O5 catalysts supported on anatase TiO2 that were prepared using sol-gel formation and impregnation procedures were investigated. The effects of incorporating Mg
in sol-gel to influence the properties of the catalyst were also studied. The process provides an alternative low temperature
reaction pathway for reducing emissions of hazardous air pollutant (HAPs) such as methanol and total reduced sulfur compounds
(TRS) from pulp and paper mills. The bulk and surface composition of the catalysts were determined by XRD and SEM-EDAX, respectively.
The X-ray diffraction patterns of the vanadia–titania catalysts showed mainly the anatase phase of TiO2. Temperature programmed desorption of methanol from the different catalyst showed that the α and β peaks differ significantly
with V content and addition of Mg. The combination of gas phase and surface reactions on the V/TiO2 catalysts reduced the amount of ozone required for high degradation of methanol to mainly COx with small quantities of methyl formate. In the absence of ozone the catalysts showed very low activity. It is hypothesized
that the ozone is directly influencing the V4+ and V5+ redox cycle of the catalyst. Oxidation of methanol is influenced by the operation variables and catalyst properties. The
results of this study revealed that the V content has significant influence on the catalyst activity, and the optimum vanadia
loading of about 6 wt%. Higher turnover frequencies were observed over sol-gel catalysts than with catalysts prepared by the
impregnation method. 相似文献
Positive matrix factorization (PMF) was used to identify factors affecting fog formation in Kanpur during the ISRO-GBP land campaign-II (LC-II) in December 2004. PMF predicted factors were validated by contrasting the emission strength of sources in the foggy and clear periods, using a combination of potential source contribution function (PSCF) analysis and quantitative emission inventory information. A time series aerosol chemical data set of 29 days and 12 species was decomposed to identify 4-factors: Secondary species, Biomass burning, Dust and Sea salt. PMF predicted particle mass with a satisfactory goodness-of-fit (slope of 0.83 ± 0.17 and R2 of 0.8), and strong species within 11–12% relative standard deviation. Mean contributions of anthropogenic factors were significantly higher during the foggy period for secondary species (2.9 ± 0.3) and biomass burning (1.2 ± 0.09) compared to the clear period. Local sources contributing to aerosols that mediated fog events at Kanpur, based on emissions in a 200 km × 200 km area around Kanpur city were thermal power plants and transportation (SO2) and biofuel combustion (BC and OM). Regional scale sources influencing emissions during the foggy period, in probable source regions identified by PSCF included thermal power plants, transportation, brick kilns and biofuel combustion. While biofuel combustion and transportation are distributed area sources, individual point sources include coal-fired thermal power plants located in Aligarh, Delhi, Ghaziabad, Jhansi, Kanpur, Rae Bareli and Rupnagar and brick kilns located in Allahabad, Agra, Farrukhabad, Ghaziabad, Kanpur, Ludhiana, Lucknow and Rae Bareli. Additionally, in the foggy period, large areas of probable source regions lay outside India, implying the significance of aerosol incursion from outside India. 相似文献
Environmental Science and Pollution Research - This study empirically examines the impact of climate change on cereal production in selected lower-middle-income countries with a balanced panel... 相似文献
ABSTRACTMicroplastics are emerging environmental pollutants that have gained tremendous scientific interest in recent years. These micropollutants are omnipresent both in the terrestrial and aquatic environments posing a deleterious threat to the ecosystem and biodiversity. So, it is important to develop a deep understanding of the environmental fate and potential adverse impacts of microplastics on the aquatic and terrestrial environments. By critically reviewing the previously published scientific literature, the present synthesis briefly outlines the characteristics, occurrence and potential toxic effects of microplastics on terrestrial and aquatic biota. The article also focuses on some innovative approaches for sustainable remediation of macroplastics as well as microplastics. Since the concept of microplastics pollution has yet in its infancy in Bangladesh, this synthesis provides an overview of the current scenario of microplastics pollution and some future research recommendations in the context of Bangladesh which might be helpful to the novice researchers of this field. 相似文献