Browsing by Author "A.H. Khan"

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Assessment of groundwater quality with special emphasis on nitrate contamination in parts of Varanasi City, Uttar Pradesh, India
(Springer Verlag, 2018) Arif Ahamad; Sughosh Madhav; Pardeep Singh; Jitendra Pandey; A.H. Khan
In the current study, an effort was made to assess the geochemistry of groundwater by random collection of the samples from 15 different borewells located in various parts of Varanasi City, Uttar Pradesh, India. Geology of the study region is dominated by Quaternary alluvial sediments of Pleistocene to recent times where the younger alluvium receives fresh deposits of silt, clay and loam from periodic flood events. Ca–Mg–HCO3was inferred as major hydrogeochemical facies from Piper trilinear diagram. Ca–Mg type and HCO3− type were the dominating cation and anion facies, respectively. Hydrogeochemistry reveals that the cation abundance follows the order Na+> Mg2+ > Ca2+ > K+ and anion abundance HCO3− > Cl− > NO3− > SO42− > F−. As per Gibb’s plot, chemical weathering of rock minerals is affecting the quality of groundwater. Overall, most of the samples for majority of parameters lie within the allowable limits as set by WHO (guideline for drinking water quality, fourth edn, WHO, Geneva, p 340, 2004) except nitrate, which varied in the range of 40.32–78.97 mg/l. 80% of the groundwater samples in which nitrate exceeded beyond acceptable limit (50 mg/l), as per WHO standard, which may be due to poor sewerage, human excreta leakage from septic tanks, poorly maintained disposal of solid waste locally, agricultural activities, wastewater irrigation and irrigation runoff. The Water quality index (WQI) value of the study region depicts that 93% samples lie in the category of excellent water and 7% in good water category. Good positive correlation of NO3–Cl (r = 0.60) and Na–NO3 (r = 0.55) signifies an anthropogenic input of these ions into the subsurface water of the study region. The various indices such as electrical conductivity (EC), salinity, percent sodium, sodium absorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), Kelly’s ratio and magnesium ratio are used to check the fitness of ground water for irrigation uses which shows that groundwater samples of the study region is good to permissible for agricultural uses. © 2018, The Author(s).
Atmospheric Fine and Coarse Mode Aerosols at Different Environments of India and the Bay of Bengal During Winter-2014: Implications of a Coordinated Campaign
(Springer India, 2014) A. Sen; Y. Nazeer Ahammed; B.C. Arya; Tirthankar Banerjee; G. Reshma Begam; B.P. Baruah; A. Chatterjee; Anil K. Choudhuri; Amit Dhir; Trupti Das; Pitamber Prasad Dhyani; N.C. Deb; Ranu Gadi; Mangesh Gauns; Sanjay Kumar Ghosh; Abhishek Gupta; K.C. Sharma; A.H. Khan; K. Maharaj Kumari; Manish Kumar; Arun Kumar; Jagdish Chandra Kuniyal; Anita Lakhani; R.K. Meena; P.S. Mahapatra; S.W.A. Naqvi; Dharam Pal Singh; S. Pal; Sipra Panda; Rohtash; J. Saikia; P. Saikia; A. Sharma; Priyanka Sharma; M. Saxena; D.M. Shenoy; C. Viswanatha Vachaspati; S.K. Sharma; T.K. Mandal
In this paper, we present mass concentrations of particulate matter [PM2.5, PM10 size fractions and total suspended particulates (TSP)] measured simultaneously over land stations (Kullu, Patiala, Delhi, Ajmer, Agra, Lucknow, Varanasi, Giridih, Kolkata, Darjeeling, Jorhat, Itanagar, Imphal, Bhubaneswar, and Kadapa), mostly distributed across the Indo-Gangetic plain (IGP) of India as well as in the marine atmosphere over Bay of Bengal (BoB) in the period from 20 January to 3 February, 2014. The main objective of this study was to quantify the continental outflow of particulates (PM2.5, PM10 and TSP) from IGP and associated regions into the BoB along with low level north-east wind flow during winter monsoon period. The present study provides a glimpse of the aerosol loading over the IGP region. During this campaign, the highest average PM2.5 (187.8 ± 36.5 µg m−3, range 125.6–256.2 µg m−3), PM10 (272.6 ± 102.9 µg m−3, range 147.6–520.1 µg m−3) and TSP (325.0 ± 71.5 µg m−3, range 220.4–536.6 µg m−3) mass concentrations were recorded at Varanasi, Kolkata and Lucknow over middle and lower IGP regions. The PM2.5 (average 41.3 ± 11.9 µg m−3; range 15.0–54.4 µg m−3), PM10 (average 53.9 ± 18.9 µg m−3; range 30.1–82.1 µg m−3) and TSP (average 78.8 ± 29.7 µg m−3; range 49.1–184.5 µg m−3) loading over BoB were found to be comparable to land stations and suggests possible continental outflow. Over the continental region, the highest PM2.5/PM10 ratio was recorded at Delhi (0.87). The PM2.5/PM10 ratio over BoB (0.77) was found to be quite high and comparable to Varanasi (0.80) and Agra (0.79). © 2014, Metrology Society of India.
Study of the carbonaceous aerosol and morphological analysis of fine particles along with their mixing state in Delhi, India: A case study
(Springer Verlag, 2015) S. Tiwari; A.S. Pipal; Philip K. Hopke; D.S. Bisht; A.K. Srivastava; Shani Tiwari; P.N. Saxena; A.H. Khan; S. Pervez
Because of high emissions of anthropogenic as well as natural particles over the Indo-Gangetic Plains (IGP), it is important to study the characteristics of fine (PM2.5) and inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter 2013. The mean mass concentrations of fine (PM2.5) and inhalable (PM10) (continuous) was 117.6±79.1 and 191.0± 127.6 μg m−3, respectively, whereas the coarse mode (PM10–2.5) particle PM mass was 73.38±28.5 μg m−3. During the same period, offline gravimetric monitoring of PM2.5 was conducted for morphological analysis, and its concentration was ~37% higher compared to the continuous measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0 μg m−3 during the daytime, while at night it was 41.2 and 10.1 μg m−3, respectively. The average OC/EC ratio was 8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of aerosols on climate, and its mean value was 0.52 and 1.79 during night and day, indicating the dominance of absorbing and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual particles indicates that Si is the most abundant element (~37–90%), followed by O (oxide) and Al. Circularity and aspect ratio was studied, which indicates that particles are not perfectly spherical and not elongated in any direction. Trajectory analysis indicated that in the months of February and March, air masses appear to be transported from the Middle Eastern part along with neighboring countries and over Thar Desert region, while in January it was from the northeast direction which resulted in high concentrations of fine particles. © Springer-Verlag Berlin Heidelberg 2015.
Variations in particulate matter over Indo-Gangetic Plains and Indo-Himalayan Range during four field campaigns in winter monsoon and summer monsoon: Role of pollution pathways
(Elsevier Ltd, 2017) A. Sen; A.S. Abdelmaksoud; Y. Nazeer Ahammed; Mansour ِA. Alghamdi; Tirthankar Banerjee; Mudasir Ahmad Bhat; A. Chatterjee; Anil K. Choudhuri; Trupti Das; Amit Dhir; Pitamber Prasad Dhyani; Ranu Gadi; Sanjay Ghosh; Kireet Kumar; A.H. Khan; M. Khoder; K. Maharaj Kumari; Jagdish Chandra Kuniyal; Manish Kumar; Anita Lakhani; Parth Sarathi Mahapatra; Manish Naja; Dharam Pal; S. Pal; Mahammad Rafiq; Shakil Ahmad Romshoo; Irfan Rashid; Prasenjit Saikia; D.M. Shenoy; Vijay Sridhar; Nidhi Verma; B.M. Vyas; Mohit Saxena; A. Sharma; S.K. Sharma; T.K. Mandal
Both in-situ and space-borne observations reveal an extremely high loading of particulates over the Indo-Gangetic Plains (IGP), all year around. With a burgeoning population and combustion sources (fossil fuels (FFs) and biofuels (BFs)) in close proximity to each other, the IGP is widely regarded as a hotspot for anthropogenic aerosol emission in South Asia. The deteriorating air quality over this region, particularly during winters, is a cause of major concern, since the pollutants undergo long range transport from their source regions to the Indo-Himalayan Range (IHR), Bay of Bengal (BoB) and other remote areas, polluting their pristine atmospheric conditions. Seasonal reversal in winds over the Indian mainland leads to an outflow of continental pollutants into the BoB during winters and a net advection of desert dust aerosols into the IGP from southwest Asia (SW-Asia), northwest India (NW-India) and northern Africa (N-Africa) during summers. Through the course of this study, four observational campaigns were conducted for sampling the ambient PM2.5and PM10during winter and summer seasons of 2014–2015, at multiple locations (18 sites) in the IGP, IHR, and semi-arid/arid sites towards their south and west, in order to accurately determine the inter-seasonal and inter-annual changes in the aerosol loading at the sites. We have also utilized data from Moderate Resolution Imaging Spectroradiometer (MODIS) on-board Earth Observing System (EOS) Terra satellite for estimating the columnar Aerosol Optical Depth at 550 nm (AOD550) and data from EOS Terra and Aqua satellites for discovering openly burning fires in the vicinity of sampling sites. Determination of the major source regions and key transport pathways during both seasons have also been attempted, using back-trajectory cluster analyses, as well as receptor models such as PSCF and CWT. © 2017 Elsevier Ltd