Exploring the association between long-term MODIS aerosol and air pollutants data across the Northern Great Plains through machine learning analysis.

Aerosol optical depth (AOD) and Ångström exponent (AE) are the major environmental indicators to perceive air quality and the impact of aerosol on climate change and health as well as the global atmospheric conditions. In the present study, an average of AOD and AE data from Tera and Aqua satellites of MODIS sensors has been investigated over 7 years i.e., from 2016 to 2022, at four locations over Northern Great Plains. Both temporal and seasonal variations over the study periods have been investigated to understand the behavior of AOD and AE. Over the years, the highest AOD and AE were observed in winter season, varying from 0.75 to 1.17 and 1.30 to 1.63, respectively. During pre-monsoon season, increasing trend of AOD varying from 0.65 to 0.95 was observed from upper (New Delhi) to lower (Kolkata) Gangetic plain, however, during monsoon and post-monsoon a reverse trend varying from 0.85 to 0.65 has been observed. Seasonal and temporal aerosol characteristics have also been analyzed and it has been assessed that biomass burning was found to be the major contributor, followed by desert dust at all the locations except in Lucknow, where the second largest contributor was dust instead of desert dust. During season-wise analysis, biomass burning was also found to be as the major contributor at all the places in all the seasons except New Delhi and Lucknow, where dust was the major contributor during pre-monsoon. A boosting regression algorithm was done using machine learning to explore the relative influence of different atmospheric parameters and pollutants with PM2.5. Water vapor was assessed to have the maximum relative influence i.e., 51.66 % followed by CO (21.81 %). This study aims to help policy makers and decision makers better understand the correlation between different atmospheric components and pollutants and the contribution of different types of aerosols.

Statistical and spatio-temporal analyses of noise pollution level and its health impact.

Due to rapid urbanization and exponential growth in transportation; traffic noise has become a major area of concern. Noise not only disturbs our day-to-day life but also have severe adverse health effects over humans which further may lead to mortality. This paper focuses on the behavior of noise levels of Lucknow city over a decade and establishes its correlation with impact on human health in terms of annoyance and sleep disturbance. Apart from Leq, different noise parameters like L10, L50, L90, Traffic Noise Index (TNI), Noise Pollution Index (NPI), and Noise Climate (NC) have also been analyzed to understand the variation of noise. At all the locations, the noise level has been found exceeding their prescribed standards during day time and night time except at Amausi. Out of nine locations, TNI was found to be exceeding at three locations during day time and NPI exceeding at one location. However, during night time both values of TNI and NPL were observed within the limit at all the locations. From the noise map of the city during day time and night time, among all sampling locations, Charbagh has been found to be worst affected by noise pollution. A strong positive correlation has been observed among the total population, vehicular count, and day and night time noise data, which directly contribute to a higher percentage of sleep disturbance and annoyance among residents. Due to the increase in noise levels over a period of time, almost four times the population get affected by high annoyance and almost double the population get affected by sleep disturbance.

Comparative study for sorption of arsenic on peanut shell biochar and modified peanut shell biochar.

In this study, arsenite [As(III)] and arsenate [As(V)] removal efficiency of peanut shell biochar (PSB) and modified peanut shell biochar (MPSB) was compared in aqueous solutions. The modification was carried out with KMnO4 and KOH. Sorption efficiency of MPSB was relatively higher than PSB at pH 6 for As(III) (86%) and for As(V) (91.26%) for initial concentration of 1 mg/L, adsorbent dose of 0.5 g/L and 240 min equilibrium time at 100 rpm. Freundlich isotherm and pseudo-second order kinetic model suggested possible multilayer chemisorption. Fourier transform infrared spectroscopy showed that -OH, C-C, CC and C-O-C groups contributed significantly in adsorption for both PSB and MPSB. Thermodynamic study showed that the adsorption process was spontaneous and endothermic. Regeneration studies revealed that PSB and MPSB can be successfully used for three cycles. This study established that peanut shell is a low-cost, environment friendly and efficient biochar for removal of arsenic from water.

Imidacloprid biodegradation using novel bacteria Tepidibacillus decaturensis strain ST1 in batch and in situ microcosm study.

Imidacloprid is one of the frequently used insecticides. Indiscriminate use of imidacloprid makes it perilous to non-target organisms as well as the environment, including soil and water sources, thus, making its elimination from the environment an irresistible concern. Bioremediation is a technique that uses the degrading capabilities of bacteria to create an economical and reliable method of pesticide abatement. In an attempt to solve the problem arising due to imidacloprid contamination, bacterial strains possessing the ability to degrade imidacloprid were isolated from contaminated agricultural soil samples in the present study. Imidacloprid-degrading isolate, identified as Tepidibacillus decaturensis strain ST1, could effectively degrade imidacloprid in liquid media, slurry, and soil microcosms. The microcosm studies using the isolate resulted in the degradation of around 77.5% and 85% of imidacloprid (200 ppm) in sterile and unsterile soils within 45 days. In addition to biodegradation, sorption of insecticide by the plants and natural reduction of insecticide over time has also been reported. The degradation in soil follows first-order kinetics. Hydrazinecarboxamide and hydroxyurea were identified as metabolites on conducting GC-MS analysis of the degraded samples.

Spatio-temporal assessment of ambient air quality, their health effects and improvement during COVID-19 lockdown in one of the most polluted cities of India.

The present work aims to investigate seasonal variations in air pollution levels in Lucknow and assess the ambient air quality of the city together with highlighting the health impacts of major pollutants like PM10, PM2.5, SO2, NO2, Pb, Ni and aerosols from 2010 to 2019. The maximum and minimum values of PM10, PM2.5, SO2, NO2, Pb and Ni were found to be 270.75 and 122.45 µg/m3, 124.95 and 95.52 µg/m3, 25.60 and 8.05 µg/m3, 75.65 and 23.85 µg/m3, 0.66 and 0.03 µg/m3 and 0.07 and 0.01 ng/m3, respectively. Health impact of particulate matter has also been assessed with AirQ+, and it was estimated that long-term exposure of PM10 was attributed to between 37 and 48% for post-neonatal (age 1-12 months) mortality rate due to all causes, whereas long-term attributable proportions in mortality due to exposure of PM2.5 were to about 19 to 28% from all causes. Further, an attempt has also been made to evaluate the impact of lockdown amid COVID-19 on the ambient air quality of Lucknow. During the lockdown, PM2.5 levels reduced by 65% (at Gomti Nagar), 23% (at central school), 79% (at Lalbagh) and 35% (at Talkatora), due to which, air quality index of Gomti Nagar came down to 43, well below 50 which falls in the healthy range. NO2 levels also came down. However, levels of SO2 did not show significant reduction. Correlating the data between aerosol optical depth and Angstrom exponent by Pearson correlation analysis revealed a significant positive correlation (r = 0.65, P < 0.001).

Phototrophic cultivation of NaCl-tolerant mutant of Spirulina platensis for enhanced C-phycocyanin production under optimized culture conditions and its dynamic modeling.

Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C-phycocyanin (C-PC) and other valuable chemicals like carotenoids and γ-linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C-PC production in NaCl-tolerant mutant of Spirulina platensis. In this study, highest C-PC (147 mg · L-1 ) and biomass (2.83 g · L-1 ) production was achieved when a NaCl-tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl-tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C-PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (µmax ) for NaCl-tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half-saturation constant (Ks ), indicating that this strain could grow well at high concentration of NaNO3 . C-PC production rate (Cmax ) in mutant cells increased by 12.2% at almost half the value of Ks as compared to its wildtype counterpart. Moreover, the inhibition constant (Ki ) value was 207.85% higher in NaCl-tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C-PC even at high concentrations of NaNO3 .

Study of optical phase conjugation in amorphous Zn(x)-S(y)-Se(100-x-y) chalcogenide thin films using degenerate four-wave mixing.

Degenerate four-wave mixing (DFWM) experiment is performed to obtain light wavefront inversion (phase conjugation) in semiconducting chalcogenide thin films. Third order nonlinearity of amorphous Zn(x)-S(y)-Se(100-x-y) chalcogenide thin films using DFWM technique is studied at second harmonic of Nd:YAG laser. Influence of total input irradiance on phase conjugate signal is deliberated using log-log plot that has a slope of three and hence implies third order nonlinearity. The dependence of phase conjugate signal on forward beam and backward beam is also studied. The period of the grating formed by interference of forward and probe beam is determined. As the temporal overlapping and sample thickness conditions are satisfied, the third order nonlinear susceptibility, figure of merit and nonlinear refractive index of amorphous films are estimated. The nonlinear behavior is analyzed in terms of decrease in band gap with increasing Zinc and decreasing Sulfur content.

Sensitive measurement of optical nonlinearity in amorphous chalcogenide materials in nanosecond regime.

The present work focuses on the nonlinear optical behavior of chalcogenide As(2)S(3) film as well as on bulk material. The thin film of As(2)S(3) grown by thermal evaporation and bulk glass developed by melt-quenched technique has been characterized using nanosecond pulses of Nd:YAG (532 nm) and Nd:YVO(4) (1,064 nm) laser. Using Z-scan technique, the laser induced nonlinear optical parameters viz. nonlinear refractive index (n(2)), nonlinear absorption coefficient (ß) and third order nonlinear susceptibility (χ(3)) have been estimated. At 1,064 nm excitation, the materials exhibit stronger nonlinearity as compared to that of 532 nm laser. In case of As(2)S(3) thin film, observed nonlinearity attributes to two-photon absorption. The optical limiting response of chalcogenide film as well as bulk sample has also been reported. The study predicts that the As(2)S(3) thin film is a better optical limiting material than bulk glass due to relatively higher nonlinearity and lower limiting threshold.

Spatial distribution of arsenic in groundwater of southern Nepal.

Groundwater is an important source of both drinking water and of irrigation in the Terai region of Nepal. Although thousands of tubewells have been drilled in this region, the distribution of those that have been sampled and analyzed for As contamination is not consistent across the region. Based on a recent blanket tubewell testing program conducted in Nepal in 2007, preliminary data are available that allows us to provide a perspective on the As-contamination situation in drinking water of the six southern the Terai districts of Nepal. Arsenic concentrations detected in drinking water of tubewells and dug wells in these districts ranged from 0 to 770 jg L-'. It was found that the majority of the tested wells contained water that had As level below 10 jg L-', which is the WHO guideline value for exposure to As. The mean As levels detected varied from 2 jtg L-' in the Sunsari, Dhanusha, and Rupandehi districts, to 6.27 pg L-' in the Kailali district. The distribution of As levels detected, based on the NIS guideline, and expressed as a percentage thereof, was highest in the tubewells of the Bara district (3.8%), followed by the Kailali district (3.4%). Wells that were between 0- and 20-m deep contained water that had the highest percentage of As residues that exceeded both the WHO and NIS guideline values. In shallow tubewells of all six tested districts, the highest As contamination levels were found at depths of <50-m. The proportion of the population that was most often exposed to As levels >50 jig L-' occurred in the Kailali district (4%), followed by the Bara district (3.6%). Using a system developed to classify the relative vulnerability of inhabitants to As through drinking water only the Kailali and Bara districts were classified as "highly vulnerable" to As exposure. The Kota Tulsipur VDC of the Kailali district was found to be the most prominent As hotspot, wherein the majority of tubewells contained more than 50 jtg L-1 of As.

Variations in physico-chemical and microbiological characteristics of water during breeding of Cyprinus carpio in a closed hatchery system.

Physico-chemical and microbial characteristics of culture water were examined during the induced breeding of Cyprinus carpio in a controlled environmental system. Water temperature, dissolved oxygen, nitrate, phosphate, pH, ammonia nitrogen, total bacterial count, hardness, salinity, carbonate and bicarbonate were estimated before and after spawning and hatching. Average alteration in water pH before and after spawning was 7.91-7.57 and 7.86-7.58 respectively. Total hardness, carbonate and bicarbonate showed insignificant variations. Nitrate, ammonia nitrogen and phosphate contents significantly increased after spawning and hatching p < 0.05. The average increase in nitrate was from 2.94 to 8.62 microg l(-1) after spawning and 3.10 to 8.49 microgl(-1) after hatching. Ammonia nitrogen contents were sharply increased from an average of 0.011 to 1.87 mg l(-1) after spawning and 0.013 to 0.56 mg l(-1) after hatching. The average phosphates increased from 2.59 to 4.15 microg l(-1) after spawning and 2.61 to 4.03 microg l(-1) after hatching. Dissolved oxygen was sharply depleted even after a continuous aeration. Temperature played a vital role during breeding. No successful breeding was observed at a temperature of 17 degrees C or below and 31 degrees C or above. There is a significant association between temperature, spawning and hatching (p < 0.05). By optimizing temperature, the breeding success of this carp was achieved with a statistical significance of p < 0.05. Total bacterial count was significantly increased after spawning and hatching. It was related to the amount of discharge and may cause mass mortality of fish embryo and spawn in a closed hatchery system.

Differential modal Zernike wavefront sensor employing a computer-generated hologram: a proposal.

The process of Zernike mode detection with a Shack-Hartmann wavefront sensor is computationally extensive. A holographic modal wavefront sensor has therefore evolved to process the data optically by use of the concept of equal and opposite phase bias. Recently, a multiplexed computer-generated hologram (CGH) technique was developed in which the output is in the form of bright dots that specify the presence and strength of a specific Zernike mode. We propose a wavefront sensor using the concept of phase biasing in the latter technique such that the output is a pair of bright dots for each mode to be sensed. A normalized difference signal between the intensities of the two dots is proportional to the amplitude of the sensed Zernike mode. In our method the number of holograms to be multiplexed is decreased, thereby reducing the modal cross talk significantly. We validated the proposed method through simulation studies for several cases. The simulation results demonstrate simultaneous wavefront detection of lower-order Zernike modes with a resolution better than lambda/50 for the wide measurement range of +/-3.5lambda with much reduced cross talk at high speed.