Advancing Contaminant Mass Flux Analysis to Focus Remediation: The Three‐Compartment Model          下载免费PDF全文

John Horst  Scott Potter  Matthew Schnobrich  Nicklaus Welty  Ankit Gupta  Joseph Quinnan 《Ground Water Monitoring & Remediation》2017,37(4):15-22

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Overview of Natural Source Zone Depletion: Processes,Controlling Factors,and Composition Change          下载免费PDF全文

Sanjay Garg  Charles J. Newell  Poonam R. Kulkarni  David C. King  David T. Adamson  Maria Irianni Renno  Tom Sale 《Ground Water Monitoring & Remediation》2017,37(3):62-81

Natural source zone depletion (NSZD) has emerged as a practical alternative for restoration of light non‐aqueous phase liquid (LNAPL) sites that are in the later stages of their remediation lifecycle. Due to significant research, the NSZD conceptual model has evolved dramatically in recent years, and methanogenesis is now accepted as a dominant attenuation process (e.g., Lundegard and Johnson 2006 ; Ng et al. 2015 ). Most of the methane is generated within the pore space adjacent to LNAPL (Ng et al. 2015 ) from where it migrates through the unsaturated zone (e.g., Amos and Mayer 2006 ), where it is oxidized. While great progress has been made, there are still some important gaps in our understanding of NSZD. NSZD measurements provide little insight on which constituents are actually degrading; it is unclear which rate‐limiting factors that can be manipulated to increase NSZD rates; and how longevity of the bulk LNAPL and its key constituents can be predicted. Various threads of literature were pursued to shed light on some of the questions listed above. Several processes that may influence NSZD or its measurement were identified: temperature, inhibition from acetate buildup, protozoa predation, presence of electron acceptors, inhibition from volatile hydrocarbons, alkalinity/pH, and the availability of nutrients can all affect methanogenesis rates, while factors such as moisture content and soil type can influence its measurement. The methanogenic process appears to have a sequenced utilization of the constituents or chemical classes present in the LNAPL due to varying thermodynamic feasibility, biodegradability, and effects of inhibition, but the bulk NSZD rate appears to remain quasi‐zero order. A simplified version of the reactive transport model presented by Ng et al. 2015 has the potential to be a useful tool for predicting the longevity of key LNAPL constituents or chemical fractions, and of bulk LNAPL, but more work is needed to obtain key input parameters such as chemical classes and their biodegradation rates and any potential inhibitions.  相似文献   

Assessing impacts of agricultural water interventions in the Kothapally watershed,Southern India     

Kaushal K. Garg  Louise Karlberg  Jennie Barron  Suhas P. Wani  Johan Rockstrom 《水文研究》2012,26(3):387-404

The paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India, developed through integrated management and a consortium approach. The impacts of various soil and water management interventions in the watershed are compared to no‐intervention during a 30‐year simulation period by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge and outflow under no‐intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by 10–30% and better crop yields compared to no‐intervention. Water outflows from the developed watershed were more than halved compared to no‐intervention, indicating potentially large negative downstream impacts if these systems were to be implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams were less than one‐tenth. It can be concluded that the hydrological impacts of large‐scale implementation of agricultural water interventions are significant. They result in improved rain‐fed agriculture and improved productivity and livelihood of farmers in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case‐specific studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at the mesoscale. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary,West Himalaya     

Sudeep Chandra  Ankit Singh  C. P. Singh  M. C. Nautiyal  L. S. Rawat 《山地科学学报》2018,15(9):1936-1949

The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient and sampled for detailed vegetation analysis using multi summit approach as per Global observation research initiative in alpine environments(GLORIA). Species richness, diversity, and evenness among four summits as well as the interaction between environmental variables with plant communities were assessed. Monthly mean soil temperature was calculated using data retrieved from geo-precision temperature logger in order to identify the trend of soil temperature among different season and altitudinal gradient and its implications to plant communities. Soil samples were analyzed fromeach summit by collecting randomized composite soil samples. The indirect non-metric multidimensional scaling(NMDS) and direct canonical correspondence analysis(CCA) tools of ordination techniques to determine the linkage between plant species from various sample summits and biotic/abiotic environmental gradients were used in the present study. The results of the study demonstrated increase in species richness as soil temperature increases, the ecotone representing summits were found most warm summits followed by highest species richness. Annual soil temperature increased by 1.43°C at timberline ecotone. Whereas, at upper alpine zone the soil temperature increased by 0.810 C from year 2015 to 2016. S?rensen's similarity index was found to be increased between subalpine and upper alpine zone with increase in the presence of subalpine plant species at upper alpine zone. Both the ordination tools separate the subalpine summit and their respective vegetation from summits representingtimberline ecotone and upper alpine zone. Soil p H, altitude, soil cation exchange capacity were found as the key abiotic drivers for distribution of plant species.  相似文献   

N2O emissions of India: an assessment of temporal, regional and sector trends     

Amit Garg  P. R. Shukla  Jigeesha Upadhyay 《Climatic change》2012,110(3-4):755-782

This paper estimates the national level trend of India’s N₂O emissions from 1985–2005 and detailed sub-regional (594 districts) level and sector emissions for the year 2005. N₂O emissions are estimated using the latest methodologies (IPCC 2006), disaggregated activity data and indigenized emission factors. The estimates show that India’s N₂O emissions have grown from 144?Gg in 1985 to 267?Gg in 2005 exhibiting a compounded annual growth rate of 3.1%, which has been gradually declining from 4.7% over 1985–1990 to 2.4% over 2000–2005. N-fertilizer application contributed most to N₂O emissions, a 49% share in 2005 compared to 40% in 1985. Sub-regional (district-level) distribution of N₂O emissions showed rising mean and spread over the years, with average emissions per districts increasing from 305?ton N₂O per year in 1990 to 450?tons in 2005. The main reason being increased use of N-fertilizer. However crop selection plays an important role in N₂O emissions and there are crops providing high economic returns but low N-fertilizer requirements. Agriculture sector could contribute considerably to GDP even with very low N₂O emissions. Indian agriculture practices vary widely in input applications and crop yields across states. The gradual transition from traditional to modern agriculture over past two decades has enhanced the intensity of inputs like N-fertilizer. A simple correlation based on 1985–2005 trends shows that, ceteris paribus, a 10% increase in total crop production is accompanied with a 12.4% increase in N-fertilizer application and a 9.7% increase in total N₂O emissions from India.  相似文献   

Performance analysis of different predictive models for crop classification across an aridic to ustic area of Indian states   总被引：1，自引：0，他引：1  

Gaurav Shukla  Rahul Dev Garg  Hari Shanker Srivastava  Pradeep Kumar Garg 《国际地球制图》2018,33(3):240-259

The purpose of this study is to present comparative performance analysis of different machine learning algorithms for large area crop classification. Ten Indian districts with significant rabi crops viz. wheat, mustard, gram, red lentils (masoor) have been selected for the study. Most popular classical ensemble models – bagging/ARCing, random forest (RF), gradient boosting and Importance Sampled Learning Ensemble (ISLE) with traditional single model (decision tree) have been selected for comparative analysis. To incorporate dependency of large area crop in different variables viz. parent material and soil, phenology, texture, topography, soil moisture, vegetation, climate etc., 35 digital layers are prepared using different satellite data (ALOS DEM, Landsat-8, MODIS NDVI, RISAT-1, Sentinental-1A) and climatic data (precipitation, temperature). In rabi season, field survey about crop type is carried out to prepare training data. Performance is evaluated on the basis of marginal rates, F-measure and Jaccard’s coefficient of community, Classification Success Index and Agreement Coefficients. Score is calculated to rank the algorithm. RF is best performer followed by gradient boosting for crop classification. Other ensemble methods ARCing, bagging and ISLE are in decreasing order of performance. Traditional non-ensemble method decision tree scored higher than ISLE.  相似文献   

Physical Habitat Assessment of the Ganjal and Morand River Using GIS Techniques     

Reetu Sharma  Ankit Kumar  Vipin Vyas 《Journal of the Indian Society of Remote Sensing》2018,46(3):443-450

Physical habitat is the living space of in-stream biota which is an important factor that can affect both the quality and quantity of available habitat and the structure and composition of resident biological communities. It is a spatially and temporally dynamic entity determined by the interaction of the structural features of the channel and hydrological regime. Ganjal River is a left bank tributary of River Narmada and Morand river is the major tributary of it. At these rivers Physical Habitat Assessment was carried out using USEPA Rapid Bioassessment Protocols to know habitat suitability conditions in rivers for aquatic life thrive in. In the study habitat assessment parameters were scored according to the existing conditions for each section of the rivers and were categorised under four conditions i.e. optimal, suboptimal, marginal and poor. On the basis of result obtained from the study Habitat Suitability Map (HSM) was generated using GIS as an interface and it suggests that the habitat quality of both rivers is suitable for aquatic life.  相似文献   

Paleoweathering and Paleoclimatic Reconstructions using Neoproterozoic Paleosol in the Eastern Margin of the Pranhita-Godavari Basin,India     

Vijay Sharma  Pitambar Pati  M. L. Dora  Narendra K. Patel  Chinmay Dash  Parvej Alam  Aditya K. Verma  Ankit Gupta 《Journal of the Geological Society of India》2018,91(2):201-208

Paleogene sediments of the inner fold belt, Naga hills, have very well preserved ichnofossils. 16 ichnospecies have been documented among 13 ichnogenera such as Arenicolites isp., Chondrites targionii, Cylindrichnus isp., Diplocraterion parallelum, Gyrochorte isp., Ophiomorpha annulata, O. irregulaire, O. nodosa, O. rudis, Palaeophycus tubularis, Planolites beverleyensis, Scolicia palaeobullia, Skolithos linearis, Trypinites weisei, Thalassinoides horizontalis and Zoophycos isp. The ichnofossil assemblages comprise mostly domichnia and fodinichnia benthos of the Skolithos and Cruziana ichnofacies. A shallow marine nearshore to offshore marine environment with fluctuating energy condition has been envisaged.  相似文献   

Analyzing the effect of atmospheric trace elements on selected plant species     

Priyanka Sharma  Shailender Kumar  Abhinav Garg  Chirashree Ghosh 《Environmental Earth Sciences》2015,74(12):7793-7800

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A CHEMICAL STUDY OF THE IMPACT GLASSES AND BASAL TS FROM LONAR CRATER,INDIA     

W.B. Stroube  A.N. Garg  M.Z. Ali  W.D. Ehmann 《Meteoritics & planetary science》1978,13(2):201-208

Twenty-nine elements have been determined by INAA in two impact glasses and four basalts from Lonar Crater, India. The glasses are remarkably similar to the underlying core basalt samples in major, minor and trace element abundances. This suggests that impact-induced chemical fractionation during formation of the glasses from basalt is minimal for many of the principal rock and mineral-forming elements. It should be recognized that many of the most volatile trace elements were not determined in this study. Differences in the volatile trace element contents of the glasses and basalts due to either impact-induced fractionation, or incorporation of material from a volatile-rich impacting body, can not yet be excluded.  相似文献