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The photocatalytic decolorization and mineralization of Reactive Black 5 (RB5) dye in presence of TiO2 Degussa P25 has been studied using artificial light radiation in a shallow pond slurry reactor. The equilibrium adsorption of dye, influence of pH (3–11), catalyst load (0.5–3.0 g/L), and dye concentration (20–100 mg/L) on decolorization kinetics were studied. The effect of area to volume ratio of photoreactor on decolorization kinetics has been also studied. Mineralization studies were performed at optimized conditions of pH (3) and catalyst load (1.5 g/L). The maximum adsorption (26.5 mg/g) of dye was found to occur at pH 3. The apparent pseudo first order decolorization rate constant (kapp) value followed the order pH 3 > pH 11 > pH 9 > pH 7. As compared to available literature reduction in total organic carbon (TOC) was minimal by the time there was complete decolorization. Initial reduction in TOC was followed by subsequent increasing trend till complete decolorization. Final decreasing trend in TOC was observed only after complete decolorization. Twelve hours of treatment under experimental conditions reduced TOC content by 70% only. Discussion of results suggest that photocatalytic treatment of colored effluent under low UV intensity, and low A/V ratio may result in completely decolorized effluent but still having high COD. 相似文献
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Soil organic carbon (SOC) is an important aspect of soil quality and plays an imperative role in soil productivity in the agriculture ecosystems. The present study was applied to estimate the SOC stock using space-borne satellite data (Landsat 4–5 Thematic Mapper [TM]) and ground verification in the Medinipur Block, Paschim Medinipur District and West Bengal in India. In total, 50 soil samples were collected randomly from the region according to field surveys using a hand-held Global Positioning System (GPS) unit to estimate the surface SOC concentrations in the laboratory. Bare soil index (BSI) and normalized difference vegetation ndex (NDVI) were explored from TM data. The satellite data-derived indices were used to estimate spatial distribution of SOC using multivariate regression model. The regression analysis was performed to determine the relationship between SOC and spectral indices (NDVI and BSI) and compared the observed SOC (field measure) to predict SOC (estimated from satellite images). Goodness fit test was performed to determine the significance of the relationship between observed and predicted SOC at p ≤ 0.05 level. The results of regression analysis between observed SOC and NDVI values showed significant relationship (R2 = 0.54; p < 0.0075). A significant statistical relationship (r = ?0.72) was also observed between SOC and BSI. Finally, our model showed nearly 71% of the variance of SOC distribution could be explained by SOC and NDVI values. The information from this study has advanced our understanding of the ongoing ecological development that affects SOC dissemination and might be valuable for effective soil management. 相似文献
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Dharmendra Kumar Verma Gouri Sankar Bhunia Pravat Kumar Shit Ashwani Kumar Tiwari 《Journal of the Geological Society of India》2018,91(6):743-748
The paper presents results of research to determine the health risk of potentially toxic elements (PTEs) in soils of gold mining area in Ilesha, Southwestern Nigeria. Eighteen top soil samples were collected and analysed for PTEs using ICPMS. The pollution level in soils were assessed using pollution load index (PLI) and potential ecological risk index (PERI). The human health risk was assessed using hazard index (HI), non-carcinogenic risk index and carcinogenic risk index. All the PTEs were higher than crustal average values except Fe and follow the order Mn > Ba > Cr > Zn > Cu > Ni > Pb > Co >Fe > As > Cd. The soil samples can be classified as unpolluted to moderately polluted (0.18-1.23) and low risk (15.28-94.24) based on PLI and PERI respectively. The values of hazard Index (HI) calculated for child and adult population for all the pathways were <1 and pose no obvious non carcinogenic risk to the population except for ingestion pathway where 33% of the samples showed value >1 in child population. As, Co, Cd and Pb constituted high cancer risk in the study area with child at higher risk than adult. The Total Cancer Risk (TCR) in the study area based on all the pathways ranges between 0.19 -3.86 and 0.18-3.58 for child and adult respectively and the ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway. 相似文献
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P. Mandal Jainendra S. Joshi Sudesh Kumar Rajendra Bhunia B. K. Rastogi 《Pure and Applied Geophysics》2004,161(8):1635-1654
On 26 January, 2001 (03:46:55,UT) a devastating intraplate earthquake of Mw 7.7 occurred in a region about 5 km NW of Bhachau, Gujarat (23.42°N, 70.23°E). The epicentral distribution of aftershocks defines a marked concentration along an E-W trending and southerly dipping (45°) zone covering an area of (60 × 40) km2. The presence of high seismicity including two earthquakes of magnitudes exceeding 7.7 in the 200 years is presumed to have caused a higher level of shallow crustal heterogeneity in the Kutch area; a site lying in the seismic zone V (zone of the highest seismicity for potentially M8 earthquakes) on the seismic zoning map of India. Attenuation property of the medium around the epicentral area of the Bhuj earthquake covering a circular area of 61,500 km2 with a radius of 140 km is studied by estimating the coda-Qc from 200 local earthquakes of magnitudes varying from 3.0–4.6. The estimated Q0 values at locations in the aftershock zone (high seismicity) are found to be low in comparison to areas at a distance from it. This can be attributed to the fact that seismic waves are highly scattered for paths through the seismically active and fractured zone but they are well behaved outside the aftershock zone. Distribution of Q0 values suggests that the local variation in Q0 values is probably controlled by local geology. The estimated Q0 values at different stations suggest a low value of Q=(102 ± 0.80)*f(0.98 ± 0.02) indicating an attenuative crust beneath the entire region. The frequency-dependent relation indicates a relatively low Qc at lower frequencies (1–3 Hz) that can be attributed to the loss of energy due to scattering attenuation associated with heterogeneities and/or intrinsic attenuation due to fluid movement in the fault zone and fluid-filled cracks. The large Qc at higher frequencies may be related to the propagation of backscattered body waves through deeper parts of the lithosphere where less heterogeneity is expected. Based on the attenuation curve estimated for Q0=102, the ground acceleration at 240 km distance is 13% of 1 g i.e., 0.13 g agreeing well with the ground acceleration recorded by an accelerograph at Ahmedabad (0.11 g). Hence, it is inferred that the Q0 value obtained from this study seems to be apt for prediction of ground motion for the region. 相似文献
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