Pulak Das | Ambedkar University Delhi (original) (raw)

Papers by Pulak Das

Changes in land cover pattern over three decades were analysed using remote sensing technique of ... more Changes in land cover pattern over three decades were analysed using remote sensing technique of Normalised Difference Vegetation Index (NDVI) in Barak Valley region of north east India. NDVI is commonly used for studying land cover change but the classification criteria differ in different studies. NDVI classification in the present study area was based into nonforest (NDVI 0.5). Total dense forest cover continuously exhibited a decrease between 1979 and 1999 and between 1999 and 2010, the rate of decrease being 32.7 km 2 /year and 23 km 2 /year respectively. The total moderate forest cover increased continuously in over thirty years; the rate of increase has more than doubled (60.5 km 2

Joshi S., Upreti D. K. & Das P. 2011. Lichen diversity assessment in Pindari Glacier Valley of Ut... more Joshi S., Upreti D. K. & Das P. 2011. Lichen diversity assessment in Pindari Glacier Valley of Uttarakhand, India. Geophytology 41(1-2): 25-41. Based on published literature, preserved lichen specimens at herbarium in National Botanical Research Institute, Lucknow (LWG), and recent collections made from the temperate and alpine areas, the lichen diversity of Pindari Glacier valley in Uttarakhand revealed the occurrence of 283 species belonging to 77 genera and 35 families. The area exhibits much diversity of all the growth forms of lichens and is represented by 117 foliose, 104 crustose and 50 fruticose taxa. The wide range of phorophytes supports rich diversity of bark inhabiting lichens represented by 131 species. Lichen family Parmeliaceae dominates the region and is commonly distributed among different sites of Pindari. Caloplaca, Cladonia, Everniastrum and Phaeophyscia are commonly distributed genera in the valley. The available information regarding lichen diversity provides b...

International Journal on Environmental Sciences, 2012

In the present paper a geospatial analysis is performed to understand the meandering behaviour of... more In the present paper a geospatial analysis is performed to understand the meandering behaviour of Barak River in southern Assam between 1988 and 2010. Landsat images (with Thematic mapper and Enhanced thematic mapper-plus sensors) for years 1988, 1999, and 2010 are considered for the study. River Barak within the study area is digitized as polygons for three years and sinuosity index (SI) are calculated for three different segments; segment-1 (23 km), 2 (71 km), and 3 (40 km) situated at western, central, and eastern part of the study area. The SI ranged from 1.34 to 1.39, 3.21 to 3.20, and 2.05 to 1.69 in segments- 1, 2, and 3 respectively, with an overall SI for all the segments together ranging from 2.29 to 2.16. Except segment-1, all the other segments exhibited a decreasing trend in the sinuosity. The decrease in sinuosity is observed due to development of a significant cutoff near Sonai, decreasing the overall length of the river by around 9 km between 1988 and 2010. Channel s...

Tropical Ecology, 2010

The present work describes lichen diversity in a Reserve Forest in southern Assam, northeast Indi... more The present work describes lichen diversity in a Reserve Forest in southern Assam, northeast India, situated in the Indo-Burma biodiversity Hotspot. A total of 55 species distributed in 26 genera and 15 families were enumerated during the study. Two growth forms, crustose and foliose, were found. The crustose and foliose forms contributed 89 and 11 % of total species, respectively. Graphidaceae and Pyrenulaceae were the dominant families, which together constituted more than 50 % of populations. Pyrenula, Sarcographa and Graphis were the genera, which together accounted for approximately 30 % of the total lichen species. A total of 46 new species were encountered which were hitherto not reported from Assam state. Two species were found to be endemic to the Eastern Himalayan region and another four to the Indian region. The rich lichen diversity in a small forested area indicates the need for more such exploration in the region. Resumen: El presente trabajo describe la diversidad de ...

Oil and gas upstream industry in India falls under category ‘A’ as per the Environmental Impact A... more Oil and gas upstream industry in India falls under category ‘A’ as per the Environmental Impact Assessment notification, 2006, and require prior environmental clearance before any drilling activities. The industry has potential to negatively impact surrounding environment and socio-economic conditions if not handled properly. The impacts of industrial activities have been felt on air, water, soil and even biodiversity. Although significant statutory provisions are there to deal with negative impacts during different stages of activities, these are noticed in various components of environment. The present paper throws light on the environmental issues and their management associated with the industry and give details about the rules, regulations and acts present in India.

Remote Sensing Applications: Society and Environment

Ultrasonics Sonochemistry, 2016

Treatment and management of food processing waste is a major challenge for food industry. Potato ... more Treatment and management of food processing waste is a major challenge for food industry. Potato processing industry generates tremendous amount of peel and consider it as zero valued waste. Again, pomace generated after juice extraction from sweet lime pulp is considered as waste and not properly utilized. Whereas these waste could be utilized for the development of biodegradable packaging film to overcome environmental issues. Composite films were prepared with varying proportion of potato peel powder (PP) and sweet lime pomace (SLP) in the ratio of 0:1(A), 0.5:1(B), 1:1(C), 1:0.5(D), 1:0(E) with an ultrasound treatment of 45min, and 0:1(F), 0.5:1(G), 1:1(H), 1:0.5(I), 1:0(J) with an ultrasound treatment of 60min. Ultrasound was applied for 45 and 60min to film forming solutions to break down biopolymer particles small enough to form a film. All the films were analyzed for their barrier and mechanical properties. It was observed that increasing ultrasound treatment times gives better result in film properties and less PP content also gives better film properties, from these observations film G prepared with 0.5:1 (PP:SLP) showed better characteristics among all other films. Water vapor permeability, moisture absorption, water solubility, breakage strength and elongation capacity of G film were reported as 7.25×10(-9)g/Pahm, 12.88±0.348%, 38.92±0.702%, 242.01±3.074g and 7.61±0.824mm respectively. However, thermal decomposition for film G took place above 200°C. The film forming solution of selected G film, added with clove essential oil (1.5%) as an antimicrobial agent was wrapped on bread and stored it for 5days. The film was successful in lowering the weight loss, reducing the hardness and inhibition of surface microbial load from bread sample.

Present paper deals with the study of a meander in River Barak around Silchar town in Assam using... more Present paper deals with the study of a meander in River Barak around Silchar town in Assam using remote sensing and GIS, encompassing a period of thirty-four years between 1976 and 2010. Changes in planform characteristics of River Barak are analysed with the help of six remote sensing images of the years 1976, 1979, 1988, 1999, 2003, and 2010. The sinuosity of the meander is observed to be quite high (>2.3) exhibiting a decreasing trend in thirty-four years. The meander ratio ranging from 1.05 to 1.12 also exhibited a decreasing trend. The decreasing trends of sinuosity and meander ratio undermine the probability of cut-off across the meander in near future. To analyse the meander shift, three Ground Control Points (GCPs) were selected. It is observed that the western arm of the meander bend around Silchar town has shifted about 132.45 m towards northwest while the eastern arm of the bend has shifted about 61.59 m towards east and 9.88 m towards northwest at two locations respe...

Tropical Ecology

The paper discusses the application of lichen diversity in the form of Index of Atmospheric Purit... more The paper discusses the application of lichen diversity in the form of Index of Atmospheric Purity (IAP) for environmental stress study (air pollution) around a paper mill in Assam, India. Seventeen sites were selected within an area of approximately 1800 km2 around the mill to prepare a stress zone map using IAP; the values ranged between 17 and 113, delineating the area into five zones. The zones are categorised as zone II (IAP: 1 - 24), zone III (IAP: 25 - 49), zone IV (IAP: 50 - 74), zone V (IAP: 75 - 99), and zone VI (IAP > 99). Zone I, which represents IAP = 0 (or lichen desert) is not found in the study. The resultant map from interpolation of IAP exhibits resilience by lichens to the multiple stress sources like stone crushers, cement industry and urban sprawls. IAP, derived from number of species, frequency of occurrence, coverage, and sensitivity is found to be an efficient and cost effective method depicting long term stress effects on lichens and is one of the most su...

Journal of Industrial Pollution Control

Frontiers of Earth Science in China