Field Treatment of MTBE‐Contaminated Groundwater Using Ozone/UV Oxidation   总被引：1，自引：0，他引：1  

Craig L. Patterson  Fernando Cadena  Rajib Sinha  Dzung Kim Ngo‐Kidd  Abbas Ghassemi  E. Radha Krishnan 《Ground Water Monitoring & Remediation》2013,33(2):44-52

Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible.  相似文献   

High-resolution operational monsoon forecasts: an objective assessment     

A. K. Sahai  S. Abhilash  R. Chattopadhyay  N. Borah  S. Joseph  S. Sharmila  M. Rajeevan 《Climate Dynamics》2015,44(11-12):3129-3140

  相似文献   

Probabilistic assessment of one‐step‐ahead rainfall variation by Split Markov Process     

Rajib Maity 《水文研究》2012,26(21):3182-3194

In this paper, Split Markov Process (SMP) is developed to assess one‐step‐ahead variation of daily rainfall at a rain gauge station. SMP is an advancement of general Markov Process and specially developed for probabilistic assessment of change in daily rainfall magnitude. The approach is based on a first‐order Markov chain to simulate daily rainfall variation at a point through state/sub‐state transitional probability matrix (TPM). The state/sub‐state TPM is based on the historical transitions from a particular state to a particular sub‐state, which is the basic difference between SMP and general Markov Process. The cumulative state/sub‐state TPM is represented in a contour plot at different probability levels. The developed cumulative state/sub‐state TPM is used to assess the possible range of rainfall in next time step, in a probabilistic sense. Application of SMP is investigated for daily rainfall at four rain gauge stations – Khandwa, Jabalpur, Sambalpur, and Puri, located at various parts in India. There are 99 years of record available out of which approximately 80% of data are used for calibration, and 20% of data are used to assess the performance. Thus, 80 years of daily monsoon rainfall is used to develop the state/sub‐state TPM, and 19 years data are used to investigate its performance. Model performance is assessed in terms of hit rate (HR), false alarm rate (FAR), and percentage captured. It is found that percentage captured is maximum for Khandwa (70%) and minimum for Sambalpur (44%) whereas hit rate is maximum for Sambalpur and minimum for Khandwa (73%). FAR is around 30% or below for Jabalpur, Sambalpur, and Puri. FAR is maximum for Khandwa (37%). Overall, the assessed range, particularly the upper limit, provides a quantification possible extreme value in the next time step, which is a very useful information to tackle the extreme events, such as flooding, water logging and so on. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Elucidating the role of topological pattern discovery and support vector machine in generating predictive models for Indian summer monsoon rainfall   总被引：1，自引：1，他引：0  

Manojit Chattopadhyay  Surajit Chattopadhyay 《Theoretical and Applied Climatology》2016,125(1-2):93-100

  相似文献   

Identification of the best architecture of a multilayer perceptron in modeling daily total ozone concentration over Kolkata,India     

Syam S. De  Barin K. De  Goutami Chattopadhyay  Suman Paul  Dilip K. Haldar  Dipak K. Chakrabarty 《Acta Geophysica》2011,59(2):361-376

Autoregressive neural network (AR-NN) models of various orders have been generated in this work for the daily total ozone (TO) time series over Kolkata (22.56°N, 88.5°E). Artificial neural network in the form of multilayer perceptron (MLP) is implemented in order to generate the AR-NN models of orders varying from 1 to 13. An extensive variable selection method through multiple linear regression (MLR) is implemented while developing the AR-NNs. The MLPs are characterized by sigmoid non-linearity. The optimum size of the hidden layer is identified in each model and prediction are produced by validating it over the test cases using the coefficient of determination (R ²) and Willmott’s index (WI). It is observed that AR-NN model of order 7 having 6 nodes in the hidden layer has maximum prediction capacity. It is further observed that any increase in the orders of AR-NN leads to less accurate prediction.  相似文献   

Estimation of crustal discontinuities from reflected seismic waves recorded at Shillong and Mikir Hills Plateau,Northeast India     

Saurabh Baruah  Dipok K. Bora  Rajib Biswas 《International Journal of Earth Sciences》2011,100(6):1283-1292

In this study, an attempt is made to determine seismic velocity structure of the crust and upper mantle beneath the Shillong-Mikir Hills Plateau in northeast India region. The principle of the technique is to relate seismic travel times with crustal thickness above the Conrad and Moho discontinuities. Broadband digital waveforms of the local earthquakes make a precise detection of the seismic phases possible that are reflected at these discontinuities. The results show that the Conrad discontinuity is at 18–20 (±0.5) km beneath the Shillong-Mikir Hills Plateau and the Moho discontinuity is at 30 ± 1.0 km beneath the Shillong Plateau and at 35 ± 1.0 km beneath the Mikir Hills.  相似文献   

An experimental approach to strain pattern and folding in unconfined and/or partitioned transpressional deformation     

N. Ghosh  M. Chakra  A. Chattopadhyay 《International Journal of Earth Sciences》2014,103(1):349-365

Three different series of experiments were carried out with pitch (bitumen) and/or composite pitch-plasticine models to observe the spatial and temporal changes of strain pattern and/or fold styles in a tectonic zone undergoing sinistral-sense unconfined transpression. In the first series, rectangular pitch models with circular strain markers, when subjected to vertically and laterally unconstrained transpression, showed that the circular markers deformed into ellipses with long axes (maximum instantaneous stretching axis: ISA_max) oriented <45° with the plane of simple shear at the onset of deformation. This initial angle decreased with increasing angle of convergence (α = 15°, 30°, 45° and 60°) between the boundary walls. In the second series, a longitudinally pre-cut pitch block simulated a pre-existing fault zone in the crust. Lubrication along the cut was varied to simulate varying ease of fault slip. During oblique convergence, transpressional strain was partitioned between the pre-existing cut (dominantly the simple shear component) and the pitch blocks (mostly the pure shear component). Partitioning was higher for higher lubrication and lower angle of convergence in these experiments, which envisaged interesting observations on the efficiency of natural ‘partitioned transpression’ systems. In series 3, folds in a thin plasticine layer placed over the pitch block initiated parallel to the long axis of the finite strain ellipse in transpression and rotated anticlockwise with increasing strain.  相似文献   

Structural Framework of Deolapar Area, Central India and its Implications for Proterozoic Nappe Tectonics: Reply*     

A. Chattopadhyay 《Gondwana Research》2003,6(4):936-937

  相似文献   

Investigation of power-law correlations within daily total ozone time series and search for a stable node through phase portrait     

Parthasarathi Chakraborthy  Goutami Chattopadhyay  Surajit Chattopadhyay 《Comptes Rendus Geoscience》2013,345(2):55-61

In the study reported in this paper we have dealt with the intrinsic complexity of the daily total ozone time series over Mumbai, India (19°23′N, 72 15°00′E) by means of detrended fluctuation analysis and phase portrait analysis. From the detrended fluctuation analysis of first order it is revealed that the said time series is characterized by persistent power-law correlation which is stronger in shorter time scale than in the longer time scale. The phase portrait analysis is based on a non-linear autonomous system generated from regression equations; infinitely many stable nodes are found along the straight line x = 273.556 and from the behaviors of the contours, it has been revealed that the daily total ozone concentration is unlikely to go beyond 315 DU (approximately) and it is almost stable.  相似文献   

A reappraisal of relationships between northern hemispheric surface air temperatures and Indian summer monsoon rainfall     

J. Chattopadhyay  G. P. Singh 《Theoretical and Applied Climatology》1995,52(3-4):169-175

Summary Zonally averaged surface air temperatures have been analysed to form time series of surface air temperature anomalies over the tropics (TTA), extratropics (ETA), the poles (PTA) and the whole northern hemisphere (NHTA) for the period 1901–1990. The temporal statistical relationships between these temperature time series and Indian monsoon rainfall over all India (AIR), northwest India (NWR) and peninsular India (PIR) have been examined for the above period.The northern hemispheric January–February (JF) temperature correlates significantly and positively with all the three monsoon rainfall series, the regional peninsular rainfall series (PIR) displaying the best correlation. The Strongest correlation is observed during 1951–1980 for both AIR and NWR but weakened in 1961–1990. For PIR, the highest correlation is observed during 1961–1990, remaining almost stable since 1951–1980. The JF series AIR monsoon relationship showed the highest correlation over the tropics during 1901–1940, over the polar region during 1941–1980 and over the northern hemisphere during 1951–1980. AIR and NWR moreover show a significant negative relationship with simultaneous, succeeding autumn and following year TTA series, while AIR and PIR monsoon rainfall series show significant positive association with the following year PTA series.The results also suggest that cooler January–February NHTA not only lead to a poor monsoon, but a poor monsoon also leads to warmer temperatures over the tropics and cooler temperatures over the polar region in the following year.With 1 Figure  相似文献