Analysing spatio-temporal drought characteristics and copula-based return period in Indian Gangetic Basin (1901-2021).

Uncertainty and uneven distribution of monsoonal rainfall and its consequences on crop production is a matter of serious concern in India, specifically, in the Indo-Gangetic plain region. In this study, drought patterns were investigated through standardised precipitation index (SPI) of varying timescales, using the India Meteorological Department (IMD) precipitation data (1901-2021). We analysed the spatio-temporal pattern of different drought characteristics (frequency, duration, severity, intensity) of the Indian Gangetic basin using run theory. The bivariate copula method has been incorporated to combine two drought properties (severity and duration). Copula integrates multivariate distribution and considers the dependency rate among the variables. The five most widely used copulas from various copula families, elliptical (normal, t-copula) and Archimedean (Clayton, Gumbel, Frank), were estimated for modelling, and the best fit copula was selected. The study revealed that seasonal drought is more frequent and intense in the Upper and Middle Gangetic Plain, whereas annual drought is quite scattered in nature. It is worthy to mention that downward drought trends were observed in this agricultural belts significantly after 1965; specifically, in the Upper, Middle, and Trans Gangetic Plain regions. With increasing drought duration and severity, the drought return period raised, but the frequency decreased gradually. Most of the droughts characterised by less duration and severity occurred with a return period below 10 years for the whole region. The major 100 + years return period droughts were to be found after 1960 and their frequencies were significantly higher after 2000. The most recent remarkable droughts with more than 100 years of return occurred during 2008-2011 and 2016-2018 in the Upper and Middle Gangetic plains, whereas in the Lower Gangetic plain, a hundred-year return period drought was occurred during 2010-2013. This study provides agroclimatic-zones-wise significant information of drought characteristics and its nature of occurrence in the Indian Ganga Basin. The results enhance the understanding of drought management and formulation of adaptive strategies to mitigate the adverse impact of droughts.

Future prediction of water balance using the SWAT and CA-Markov model using INMCM5 climate projections: a case study of the Silwani watershed (Jharkhand), India.

The aim of this research was to simulate the future water balance of the Silwani watershed, Jharkhand, India, under the combined effect of land use and climate change based on the Soil and Water Assessment Tool (SWAT) and Cellular Automata (CA)-Markov Chain model. The future climate prediction was done based on daily bias-corrected datasets of the INMCM5 climate model with Shared Socioeconomic Pathway 585 (SSP585), which represent the fossil fuel development of the world. After a successful model run, water balance components like surface runoff, groundwater contribution to stream flow, and ET were simulated. The anticipated change in land use/land cover (LULC) between 2020 and 2030 reflects a slight increase (3.9 mm) in groundwater contribution to stream flow while slight decrease in surface runoff (4.8 mm). The result of this research work helps the planners to plan any similar watershed for future conservation.

Regional variation of drought parameters and long-term trends over India using standardized precipitation evapotranspiration index.

Analysing historical drought pattern is vital for implementation of efficient drought adaptation and mitigation policies. In this study, we examined the meteorological drought characteristics of India during 1901-2015, using Climate Research Unit (CRU) based Standardized Precipitation Evapotranspiration Index (SPEI) at multiple timescales i.e., 1 month (SPEI01), 3 month (SPEI03), 6 month (SPEI06), 12 month (SPEI12). Here, we applied K-means clustering algorithm on SPEI12 (December) to find out different clusters with distinct drought characteristics. The six different homogeneous regions, i.e., cluster1 (C1), cluster2 (C2), cluster3 (C3), cluster4 (C4), cluster5 (C5), and cluster6 (C6) identified by K mean clustering largely resemble with the clusters mentioned in previous researches. Different drought parameters (duration, frequency, intensity) have been also analysed for each cluster on a monthly, seasonal and interannual basis. The study indicates that northern part of India (C6, C3) experienced frequent droughts at shorter timescales whereas the western (C2) and north eastern (C4) part of the country encountered frequent drought occurrences at longer timescale. It is worthy to mention that the C2 region comprising the semi-arid and arid western part of the country including the great Indian desert, is vulnerable to frequent, prolonged and severe droughts at longer timescale (SPEI12). The study revealed a significant regional variation in drought trends identified by Modified Mann-Kendall (MMK) trend test. The annual trend analysis shows statistically significant (p < 0.05) increasing drought trend over C3 and C4 regions comprising the fertile Gangetic and Brahmaputra plains. The seasonal MMK trend analysis reveals significant increase (p < 0.05) in droughts over C3 (-0.006) and C4 (-0.005) during monsoon. The increasing drought trend over the Gangetic plain (C3) is prominent especially in the months of July (p < 0.05, slope = -0.005) and August (p < 0.001, slope = -0.006). The study provides a region-specific understanding of drought characteristics and long-term trends crucial for preparing adaptive strategies to minimize the cumulative impacts of droughts.

Implications of changes in temperature and precipitation on the discharge of Brahmaputra River in the urban watershed of Guwahati, India.

The urban watershed of Guwahati situated on the bank of the Brahmaputra River is one of the fastest growing cities of India. During the last two decades, water security concerns due to climatic variabilities have become a pronounced issue in the urban watershed of Guwahati. Thus, the study aims to calculate the long-term temporal trends of temperature, precipitation, extreme climate indices, and river discharge to assess the variations and patterns of hydro-climatic variations in the urban watershed of Guwahati from 1991 to 2019. Furthermore, the current study also tries to correlate these extreme climatic indices to river discharge to determine the degree of hydro-climatic variations. The Mann-Kendall statistical techniques and Sen's estimator were used to calculate the statistical significance, stability, and averaged magnitude of trends in the hydro-meteorological data. The result shows that the wetness indices, R20 and RX5Day, reported a decline in Guwahati's urban watershed from 1991 to 2019, resulting in a reduction in intensity and duration of heavy rainfalls while the dry spell (CDD) has been more distinct in the study area with a rise in the average temperature by 0.023 °C/year. Similarly, the most significant statistical trend was found in the monsoonal discharge of the Brahmaputra with a negative trend of - 204.16 m3/s/year. The results also show that fluctuations in rainfall patterns have a direct impact on the discharge of the Brahmaputra. These phenomena can affect the quantity of river water resulting in a severe impact on water security in the study area.

Changing pattern of urban landscape and its effect on land surface temperature in and around Delhi.

The last couple of decades have seen remarkable spatial growth in the urban areas of developing countries. The process of urbanization is directly linked with land transformation which can be an effective way to monitor the spatio-temporal pattern of urban growth. New Delhi, the capital city of India has experienced a large-scale urban growth during the last decade. In order to identify the pattern of urban expansion in and around Delhi, the present study aims to assess the process of land transformation using multi-temporal Landsat datasets (1977-2014). The areas under various land use and land cover (LULC) extracted by support vector machine (SVM) hybrid classifier reveal asignificant change in the LULC pattern of the area. A good agreement was found between field-based information and maps generated using satellite images (kappa ≥ 0.84). Land transformation maps indicate rapid growth of few urban centres located outside Delhi National Capital Territory (NCT), like Gurgaon, Gautam Buddha Nagar, Faridabad and Ghaziabad. These centres have been remarkably expanded because of transformation of agricultural and vegetated lands. However, green patches within the city have not been affected by the consequences of urbanization. In tune with the rapid urbanization in the periurban centres of Delhi, the Moderate Resolution Imaging Spectro-radiometer (MODIS)-derived land surface temperature (LST) images revealed significant change in the level of LST. The inter-relationship of impervious surface fraction (ISF) and LST proves a good agreement between them. The increasing trend observed in the long-term (1987-2011) summer temperature data obtained from India Meteorological Department (IMD) indicates the rise of mean summer temperature in the last few decades. Land transformation along with rapid urbanization especially in the periurban areas of Delhi NCT played a key role in the increasing trend of surface temperature.

Field effect transistors and RC filters from pencil-trace on paper.

We report the fabrication of Resistor-Capacitor (RC) filters and field effect transistors (FETs) based on pencil drawings on paper, which contain turbostratic graphite crystallites as evidenced from Raman analysis. Pencil drawings have been employed as resistor and an ion gel, 1-butyl-3-methylimidazolium octyl sulfate mixed with polydimethylsiloxane (PDMS) as dielectric, for the fabrication of RC filters with a cut-off frequency of 9 kHz. With ion gel as gate dielectric, an ambipolar electric field effect has been obtained from the pencil-trace at low operating voltages. The carrier mobilities were found to be ∼106 and 59 cm(2) V(-1) s(-1) for holes and electrons, respectively. The mobility value showed only 15% variation among the devices tested, truly remarkable given the simplicity of the fabrication process.

Genotoxicity of sludges, wastewater and effluents from three different industries.

Many surface waters in Europe, Asia and South America have been reported to be contaminated with genotoxic substances. Therefore, it is important to establish strategies for identification of the most critical sources. In this study, we used a battery of four genotoxicity assays namely chromosomal aberration, DNA strand break, DNA laddering and P53 accumulation tests in mononuclear blood cells. Before cleaning of wastewater high levels of genotoxic contamination could be observed. For instance, we observed an increase in chromosomal aberrations from 2.6 +/- 1.1 (aberrant cells in %; control), to 33.6 +/- 6.6 in a petrochemical plant, 29.4 +/- 3.3 in a petroleum refinery and 14.4 +/- 1.8 in a coke plant of steel industry. A good correlation between the four assays was found. The most sensitive and reproducible results were obtained with the chromosomal aberration assay. Interestingly, clear differences in the efficiency of wastewater cleaning in three different treatment plants were observed. The first and second treatment plants in petrochemical industry and coke plant of steel industry completely eliminated genotoxicity of the wastewater. However, the third plant in petroleum refinery could achieve a reduction in genotoxicity but significant genotoxic contaminations were still present. In conclusion, our battery of genotoxicity tests allows the identification of critical sources contributing to contamination of surface waters.

Modulatory effect of distillate of Ocimum sanctum leaf extract (Tulsi) on human lymphocytes against genotoxicants.

OBJECTIVE: To study the modulatory effect of distillate of Ocimum sanctum (traditionally known as Tulsi) leaf extract (DTLE) on genotoxicants. METHODS: In the present investigation, we studied the antigenotoxic and anticlastogenic effect of distillate of Tulsi leaf extract on (i) human polymorphonuclear leukocytes by evaluating the DNA strand break without metabolic activation against mitomycin C (MMC) and hexavalent chromium (Cr+6) and (ii) human peripheral lymphocytes (in vitro) with or without metabolic activation against mitomycin C (MMC), hexavalent chromium (Cr+6) and B[a]P by evaluating chromosomal aberration (CA) and micronucleus assay (MN). Three different doses of DTLE, 50 microL/mL, 100 microL/mL, and 200 microL/mL were selected on the basis of cytotoxicity assay and used for studying DNA strand break, chromosomal aberration and micronucleus emergence. The following positive controls were used for inducing genotoxicity and clastogenicity: MMC (0.29 micromol/L) for DNA strand break, chromosomal aberration and 0.51 micromol/L for micronucleus assay; Potassium dichromate (Cr+6) 600 micromol/L for DNA strand break and 5 micromol/L for chromosomal aberration and micronucleus assay; Benzo[a]pyrene (30 micromol/L) for chromosomal aberration and 40 micromol/L for micronucleus assay. The active ingredients present in the distillate of Tulsi leaf extract were identified by HPLC and LC-MS. RESULTS: Mitomycin C (MMC) and hexavalent chromium (Cr+6) induced statistically significant DNA strand break of respectively 69% and 71% (P<0.001) as revealed by fluorometric analysis of DNA unwinding. Furthermore, the damage could be protected with DTLE (50 microL/mL, 100 microL/mL, and 200 microL/mL) on simultaneous treatment. Chromosomal aberration and micronucleus formation induced by MMC, Cr+6 and B[a]P were significantly protected (P<0.001) by DTLE with and without metabolic activation. CONCLUSION: Distillate of Tulsi leaf extract possesses antioxidants contributed mainly by eugenol, luteolin and apigenin as identified by LC-MS. These active ingredients may have the protective effect against genotoxicants.

Decolorisation and detoxification of Direct Blue-15 by a bacterial consortium.

Studies were carried out on decolorisation and biotransformation of the dye Direct Blue-15 into 3,3'-dimethoxybenzidine (O'-dianisidine) and a sulphonated derivative by a five-member bacterial consortium. Chromatographic studies revealed further complete biodegradation of 3,3'-dimethoxybenzidine coupled with release of ammonia, but the recalcitrant sulphonated derivative persisted. The microorganisms identified in the mixed consortium by 16S rDNA sequence analysis were Alcaligenes faecalis, Sphingomonas sp. EBD, Bacillus subtilis, Bacillus thuringiensis and Enterobacter cancerogenus. The cytotoxicity data showed a significant reduction in the toxicity (P<0.001) of the degraded dye as evidenced from the number of viable human polymorphonuclear leukocyte cells present.

Anticlastogenic effect of redistilled cow's urine distillate in human peripheral lymphocytes challenged with manganese dioxide and hexavalent chromium.

OBJECTIVE: To study the anticlastogenic effect of redistilled cow's urine distillate (RCUD) in human peripheral lymphocytes (HLC) challenged with manganese dioxide and hexavalent chromium. METHODS: The anticlastogenic activity of redistilled cow's urine distillate was studied in human polymorphonuclear leukocytes (HPNLs) and human peripheral lymphocytes in vitro challenged with manganese dioxide and hexavalent chromium as established genotoxicants and clastogens which could cause induction of DNA strand break, chromosomal aberration and micronucleus. Three different levels of RCUD: 1 microL/mL, 50 microL/mL and 100 microL/mL, were used in the study. RESULTS: Manganese dioxide and hexavalent chromium caused statistically significant DNA strand break, chromosomal aberration and micronucleus formation, which could be protected by redistilled cow's urine distillate. CONCLUSION: The redistilled cow's urine distillate posseses strong antigenotoxic and anticlastogenic properties against HPNLs and HLC treated with Cr+6 and MnO2. This property is mainly due to the antioxidants present in RCUD.

Protective effect of distillate and redistillate of cow's urine in human polymorphonuclear leukocytes challenged with established genotoxic chemicals.

OBJECTIVE: From the ancient period cow's urine has been used as a medicine. In Veda, cow's urine was compared to the nectar. In Susrut, several medicinal properties of cow's urine have been mentioned and are known to cause weight loss, reversal of certain cardiac and kidney problems, indigestion, stomach ache, edema, etc. However, the literature and scripture did not mention the antigenotoxic properties of cow's urine. METHODS: In the present investigation, the antigenotoxic/antioxidant properties of cow's urine distillate and redistillate were studied in vitro. The antioxidant status and volatile fatty acid levels were determined. Actinomycin-D (0.1 micromol/L) and hydrogen peroxide (150 micromol/L) were used for inducing DNA strand break with 0.1% DMSO as negative control. Dose for the antigenotoxic effect of cow's urine was chosen from the dose response study carried out earlier. RESULTS: Both actinomycin-D and H202 caused statistically significant DNA unwinding of 80% & 75% respectively (P < 0.001) as revealed by fluorimetric analysis of DNA unwinding (FADU), and the damage could be protected with the redistilled cow's urine distillate (1, 50 & 100 microL) in simultaneous treatment with genotoxic chemicals. CONCLUSION: The redistillate of cow's urine was found to possess total antioxidant status of around 2.6 mmol, contributed mainly by volatile fatty acids (1500 mg/L) as revealed by the GC-MS studies. These fatty acids and other antioxidants might cause the observed protective effects.