Search

• Vertical column density and column averaged dry air concentrations of GHGs were retrieved from FTIR using GFIT model. • Seasonal and interannual variations of GHGs were studied. • FTIR retrieved X CO 2 and X CO data were compared with satellite data. Solar absorption spectra collected using a ground-based Fourier Transform Infrared (FTIR) Spectrometer were used to retrieve the column-averaged concentrations (X) of CO 2 , CH 4 , CO, and N 2 O during the years 2016–2019 in the Suburban region of Shadnagar, Telangana, India. For the research period, the diurnal mean amplitudes of X CO 2 , X CH 4 , X CO, and X N 2 O are ∼ 13 ppmv, ∼50 ppbv, ∼13 ppbv, and ∼ 19 ppbv respectively. Strong seasonality at the study site is indicated by the seasonal variations of X CO 2 and X CO of 18.3 ppmv and 39.2 ppbv, respectively. Additionally, we compared FTIR data to X CO 2 detected by Orbiting Carbon Observatory-2 (OCO-2) and CO columns from Measurements of Pollution in the Troposphere (MOPITT). For the X CO 2 and CO columns, the comparison research shows a mean relative bias between FTIR data and satellite data of 0.92 % and 0.71 %, respectively. The FTIR and satellite data show a Pearson correlation coefficient (r) of 0.71 (X CO 2 , N = 26 co-located) and 0.60 (CO columns, N = 44), respectively. The findings demonstrate a good agreement between our data and satellite data. [ABSTRACT FROM AUTHOR]

Introduction: Dental anxiety is a common problem among children, leading to missed dental appointments and neglect of oral health. Conscious sedation is a technique used in dental clinics to alleviate anxiety and enhance the patient's experience. However, parents often lack understanding about conscious sedation, which can hinder their consent for the procedure for their child. Aim: To assess parents' knowledge, attitudes, and perceptions towards conscious sedation in dental care settings. Materials and Methods: This study employed a pre-test/post-test quasi-experimental design and involved 400 parents (aged 21-40 years) whose children, aged 3 to 16 years, were randomly selected to complete a questionnaire survey at the Department of Pedodontics and Preventive Dentistry at Rajarajeswari Dental College and Hospital in Bengaluru, Karnataka, India. The survey was conducted between December 2022 and March 2023, spanning a period of four months. Data collection methods included a pre-education questionnaire and a posteducation questionnaire after an educational intervention. The collected data underwent statistical analysis, utilising mean, Standard Deviation (SD), Analysis of Variance (ANOVA), Wilcoxon's signed rank, and Tukey's posthoc tests. Results: Prior to education, 393 (98.25%) of the study population were unaware that conscious sedation was safe and easy. It was observed that 368 (92%) of the participants opposed conscious sedation for their child, but following education, 400 (100%) agreed, resulting in a 95.2% shift in perception. Conclusion: The study revealed that, before the intervention, the majority of parents were unaware of and opposed to conscious sedation, indicating a significant knowledge gap. However, the implementation of educational interventions during dental visits, led by dentists, played a crucial role in improving their knowledge and significantly changing their attitude, with 400 (100%) agreeing to the use of conscious sedation. [ABSTRACT FROM AUTHOR]

The use of fixed emission factors (EFs), combined with insufficient temporal distribution, leads to substantial uncertainties in current emission inventories for India, the world's second-largest producer and consumer of synthetic N-fertilizers. Our study aimed to improve the NH 3 and N 2 O emission estimates by utilizing crop-specific district-level activity data and refined EFs tailored to Indian conditions. In this study, a comprehensive NH 3 and N 2 O emission inventory (EI) is methodically developed at 0.1° * 0.1° spatial and monthly temporal resolution for the year 2018-19 considering 52 crops. The data for developing this inventory is aggregated through detailed field surveys, conducted across 102 districts of 14 states, and relevant government databases. EFs have been adjusted for the Indian context by refining them to reflect local conditions through consideration of ambient temperature, application rate, and other factors. Further, upon preparing an EI for FA, a spectrum of mitigation strategies are evaluated to assess their effectiveness in reducing emissions. Yearly total NH 3 and N 2 O emissions amount to 3.15 Tg and 138.53 Gg, with urea fertilizer as the dominant contributor accounting for 93.85% and 96.44% of emissions, respectively. Key crops such as rice, wheat, maize, sugarcane, and cotton collectively represent approximately 82% of the total N consumption. The state of Uttar Pradesh emerges as the largest emitter, contributing 706.5 Gg and 25.31 Gg of NH 3 and N 2 O emissions, respectively. Conversely, PB and HR exhibit the highest NH 3 emissions per capita. Temporally, NH 3 emissions peak in August, while N 2 O emissions peak in July, with both pollutants reaching their nadir in February. Among the array of mitigation strategies assessed in this study, 'adhering to recommended fertilizer doses' and 'incorporating urease inhibitors' demonstrated substantial potential for reducing emissions. The current study aids policymaking to mitigate the environmental and health impacts of atmospheric emissions from synthetic N-fertilizers. Future researchers can adopt this study as a benchmark to improve Indian FA emission estimates, which helps in promoting sustainable agricultural practices and contributes to climate change mitigation efforts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

We investigated methane (CH 4) and nitrous oxide (N 2 O), two important greenhouse gases (GHGs) emissions using the closed chamber method from a flooded rice field in Brahmaputra valley of Assam, northeast part of India. We tried to understand the factors responsible for the emission and identify appropriate agro-technologies for their mitigation. Various factors like water level, drainage management, soil organic carbon management, crop management, fertilizer amendment, cultivar type etc. affect the GHG production and emission from the flooded rice soil. In this study, six treatments were employed, namely, farmer's practice (FP), recommended fertilizer dosage (RDF), direct seeded rice (DSR), intermittent wetting drying (IWD), use of efficient methanotrophs (MTH), and use of ammonium sulfate as a nitrogen source for real-time nitrogen management using leaf color chart, (AS). GHG flux was measured through the static closed chamber technique. Soil temperature, pH, and redox potential (Eh) and other soil physico-chemical and biological properties that have a potential role in GHG emission were also assessed. The lowest CH 4 flux was observed in IWD treatment. The highest CH 4 but lowest N 2 O flux was observed in RDF thus portraying a tradeoff relationship among these two GHGs. The highest N 2 O flux was observed in AS. Changes in Eh strongly altered CH 4 and N 2 O emissions. The CH 4 flux for the growing season varied from 62.5 to 86.3 kg ha−1 with an average of 72.4 kg ha−1. The average N 2 O flux was 0.89 kg ha−1 with values fluctuating between 0.72 – and 1.08 kg ha−1. The findings of this study could assist in understanding the factors affecting the source, production, and sink of these two important GHGs. IWD, along with judicious N-based fertilizer use, could provide significant respite from GHG emissions in rice-based agriculture. These climate-smart strategies not only reduce emissions but also have the potential to improve yield. [Display omitted] • Minimum CH 4 emission observed in intermittent wetting drying (IWD) treatment. • Minimum N 2 O emission observed in recommended fertilizer dose treatment (RDF). • RDF showed the highest CH 4 emission portraying a trade-off relationship with N 2 O. • IWD resulted in the lowest GWP, GHGI and highest yield among the six treatments. [ABSTRACT FROM AUTHOR]

Background and Aims: Conscious sedation plays a significant role in in-office pharmacological behavior management for short-term procedures in children and apprehensive adults. The advantage conscious sedation provides is by improving quality of care provided by decreasing pain and anxiety while maintaining a patent airway and adequate spontaneous ventilation. Methodology: Present review was conducted to evaluate recent trends regarding use of in-office pharmacological sedation agents in India. A rigorous search was conducted through five electronic databases namely PubMed, Scopus, Web of Science, Cochrane Database, and CTRI (Clinical Trial Registry – India). The search period was defined to be last 5 years, that is, from 1st January 2014 to 31st July 2019. Terminologies "Conscious Sedation," "In-office Sedation," "Midazolam," "Nitrous Oxide," "India" were included in the search. The Boolean Operation "OR" and "AND" were applied to combine the terminologies. Results: A total of 20 studies were identified following strict inclusion and exclusion criteria. The included studies were evaluated for study design, speciality involved, number of individuals and their age groups, drugs compared along with route and dosage, procedures undertaken, place of study and results. Dental fraternity (13) had more number of trials conducted as compared to medical fraternity (7) in the stimulated period, with South Indian region having maximum trials registered or published. Conclusion: Midazolam was observed to the drug of choice for in-office sedation procedures in Indian Scenario. The limitation of study is that the published clinical studies are limited to a few states of India. [ABSTRACT FROM AUTHOR]

Given that wetlands, especially man-made wetlands including paddy fields, are a major source of the greenhouse gases methane and nitrous oxide, a study of the present status of knowledge in this area was carried out with reference to India. Based on printed material, digital repositories, and personal correspondence an up-to-date assessment of all studies reported so far has been conducted. It is shown that despite India having 4.6% of its area covered by natural or man-made wetlands, being home to a very large number of wetlands, and being the second largest cultivator of paddy in the world, its wetlands—including paddy fields which are intermittently flooded as typical wetlands are—have been very poorly studied in terms of their GHG emissions. Even the reports that are available have been mostly confined to a few regions of India, and as many as seven of the most wetland-rich states—Bihar, Chhattisgarh, Jharkhand, Madhya Pradesh, Maharashtra, Himachal Pradesh, and Jammu & Kashmir—have not been studied in this respect at all. A major finding is that, contrary to a recent report published by authors based in USA, intermittently irrigated rice fields have not been found to emit exceptionally high quantities of nitrous oxide. The study brings out the urgent need for carrying out assessments of GHG emissions from wetlands throughout India with a view to finding strategies to minimize such emissions. [ABSTRACT FROM AUTHOR]

A study was conducted in lab for synthesizing and characterizing the behavior of the nanoclay-polymer composites (NCPCs). Furthermore, greenhouse experiments carried out to investigate the effects of NCPCs application on crop yield, nutrient uptake, soil nitrogen availability and N2O emission. Wheat flour (WF), sodium alginate (Na-Alg) and acrylic acid (AA)+ acrylamide (Am) (AA+Am) NCPCs were synthesized via free radical polymerization and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (SEM-EDX) and transmission electron microscopy (TEM). At lower dose NCPCs, resulted in significantly equal grain yield in rice and wheat with 100% urea treatment with reduced amount of N2O emissions. Yield-scaled N2O emissions of rice and wheat under T9 [NCPC (AA+AM+Clay) (75% N of RDF) + PK (full dose)] treatment was respectively 19.8 and 25.5% lower than urea treatment. These findings demonstrate that there is a great potential to increase crop yields with lower N2O emissions through use of innovative fertilizer technique in India. [ABSTRACT FROM AUTHOR]

In India, large quantities of organic amendments such as crop residues (550 mt yr-1), municipal solid waste (48 mt yr-1), animal manures (182 mt yr-1) and other sources are produced. Recycling these organic amendments in agriculture has several beneficial effects such as improving plant growth, yield, soil carbon content, and microbial biomass and activity. Nevertheless, organic amendment applications have some disadvantages such as nutrient eutrophication and greenhouse gas (GHG) emission. Agriculture sector emits substantial quantities of GHGs (carbon dioxide-CO2, methane-CH4, and nitrous oxide-N2O). Though quantity wise CH4 and N2O emissions are less than CO2, they have higher global warming potential. Although there have been studies on the role of chemical fertilizer application on GHG emission, there have been very few studies on the effect of organic amendments application on GHG emission in agricultural soils. We reviewed quantification of various organic amendments used in agriculture that include manures, municipal solid waste, green manuring, crop residues and other miscellaneous organic amendments, major processes for GHG emission, and impact of organic amendment application on GHG emission from soil. The article aims to highlight the management practices to mitigate the emission and the future research needs in relation to nitrogen and carbon dynamics in soil for judicious use of organic amendments in agriculture to maintain soil health with minimum impact on GHG emission from agriculture. [ABSTRACT FROM AUTHOR]

Introduction: Fear, anxiety, and pain have been associated with the practice of dentistry for a very long time and are believed to be one of the reasons for not seeking dental treatment. The quality of dental treatment and care provided is usually affected by the apprehension and unwillingness of the patient. Several behavioral management techniques have evolved since to make dental treatment comfortable for both the patient and the doctor. Nitrous oxide conscious sedation is now being considered as a safe and effective method of anxiolysis. Hence, acquiring knowledge regarding its use and effects has become mandatory for general dental practitioners. Aim: To assess the knowledge, attitude, and awareness of general dental practitioners about the use of nitrous oxide inhalation sedation as a technique to reduce anxiety and fear of dental patients. Materials and Methods: Study Design - Cross-sectional study. This study will be conducted among the Dental practitioners of Kollam, Kerala, India. A prevalidated online questionnaire was provided to the dental practitioners through mail and WhatsApp. Questions on sociodemographic profile, knowledge, awareness, exposure, and practice on nitrous oxide conscious sedation were included. Results: The study is ongoing, and the results are awaited. Conclusion: The study is ongoing. [ABSTRACT FROM AUTHOR]

Rice–wheat (RW) cropping system in India is a major source of N2O emissions. In such system, defining N rates that deliver minimal N2O emissions and economically optimum yield would benefit both food production and the environment. We measured yield and N2O fluxes from RW systems in Northwest IGP under two tillage systems and five N rates (0, 75, 150, 225 and 300 kg N ha−1) for both rice and wheat using static chamber method. Seasonal pattern of N2O emission was mainly influenced by fertilizer and water application events with no significant effect of tillage systems. Mean annual N2O emission from RW system was 1.49 kg N ha−1 in N75 plot and 2.97–3.04 in the plots receiving ≥150 kg N ha−1. On average, the yield-scaled N2O emissions of rice and wheat were 0.25 and 0.52 kg N2O–N mg−1, respectively. Our finding suggests that N rates between 120–200 kg N ha−1 in rice and 50–185 kg ha−1 in wheat provide the most economical returns and application rates beyond these ranges would be both economically and environmentally unsustainable. Within the range of N rate studied, fertilizer-induced N2O-EF for rice and wheat were 0.41% and 0.79%, respectively. [ABSTRACT FROM AUTHOR]

Introduction  There is a lack of data and consensus about the practices and policies regarding performing colonoscopy in India. We surveyed gastroenterologists to assess their practices and policies of performing colonoscopy. Methodology  A questionnaire was presented to gastroenterologists all over India regarding their preference of bowel preparation and method of sedation, completeness of cecal and ileal intubation rates, preferences for inflation, use of carbon dioxide and nitrous oxide, and complications faced. Results  Of the 350 surveys, 307 had completely responded (88%). Only 18% of the centers were conducting more than 100 colonoscopies a month and 46% denied following a colon cancer screening policy. Two bottles of liquid polyethylene glycol were the most preferred preparation. A total of 21% did not prefer any sedation at all. Nitrous oxide was used by only 5.6% of doctors. Ileal intubation rate was >96% in 34% of centers and cecal intubation rate >96% in 58% of centers. Air was used for inflation by 58%, while 39% used CO 2. A total of 40% of the respondents believe CO 2 inflation would improve cecal intubation rate, while 9.4% believed otherwise. While one third found CO 2 inflation unnecessary and 14% not cost-effective, three fourths were still interested in setting up a CO 2 facility. Reasons for not using nitrous oxide were practical/administrative difficulty (46.6%), side effects (20%), and cost (16%). Still more than half surveyed would consider using Entonox in future. Perforation was the most noted complication faced by respondents. Conclusions  This survey of real-world clinical practices will help to formulate practice guideline regarding colonoscopy in India. [ABSTRACT FROM AUTHOR]

Urbanization, industrialization and human population explosion not only increased the global power demand, but also led to global warming, pollution and climate change. This encouraged production of power from renewable sources, and thus, hydropower development has been focused. Today, there is more than 1300 GW of installed hydropower across the world, and most of the hydroelectric projects (HEPs) are multi-purpose which includes irrigation, flood and drought mitigation and tourism. Although credited as cheap, clean and green, recent studies demonstrate that the reservoirs of HEPs produce enormous quantities of greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). A large number of estimates on the amount of GHGs from HEPs are available from across the globe. India is next only to USA and China in terms of number of large dams, and thousands of new dams are being planned or constructed, especially in the northeastern part. However, none of these projects have been analyzed in terms of production of GHGs, which is an essential prerequisite for developing such projects and to determine whether carbon emission reduction credits can be accorded or not. The present study was conducted to determine greenness of some of the HEPs of Northeast India in terms of emission of GHGs, and eligibility of the projects for carbon emission reduction credits. Further, the emission of different GHGs through various processes from the Tipaimukh HEP (Manipur) was estimated. In view of the findings, we have provided recommendations, which may be helpful in decision-making process. [ABSTRACT FROM AUTHOR]

Agricultural soils are an important source of greenhouse gas nitrous oxide (N2O) emission. The comprehensive effects of nitrogen fertilizer management on N2O emission from paddy fields of India have not been evaluated under field conditions. A 2-year field study was conducted to evaluate the effect of different nitrogen fertilizers, namely, conventional fertilizer (NPK), starch-coated urea (SCU), neem-coated urea (NCU), and normal urea alone (NUA) on soil quality, grain yield, and N2O emission from rice field. Gas samples were collected from the field at weekly intervals by static chamber technique and analyzed in a gas chromatograph. During the crop-growing season, the application of NPK resulted in the highest cumulative N2O emission (2.49 kg N2O–N ha−1) followed by NUA (2.34 kg N2O–N ha−1), NCU (2.20 kg N2O–N ha−1), and SCU (1.97 kg N2O–N ha−1). As against the application of conventional fertilizer (NPK), the application of SCU and NCU reduced the total N2O emission by 21% and 12%, respectively (p < 0.05), during the rice-growing period. The results indicate a good correlation of N2O emissions with soil organic carbon, soil mineral nitrogen, and urease activity (p < 0.05) at different stages of crop growth. Application of SCU significantly increased the rice grain productivity by 12%, 10%, and 3% over NPK (control), NCU, and NUA respectively without affecting the soil quality and nutrient status. The use of SCU improved the nitrogen use efficiency (NUE) and was the effective substitute for conventional fertilizer in terms of reducing N2O emissions from tropical rice paddy. [ABSTRACT FROM AUTHOR]

• Detailed energy, availability loss, destruction & improvement potential assessment. • Instantaneous recirculation of reject for enhanced performance. • Good condensate quality even for 6.0 wt% saline feed water. • Low evaporation area & water production cost for inclined solar distillation unit. • Generation of Atlas depicting viable sites for solar desalination in coastal India. In the current investigation, viable solar desalting sites in coastal India are identified by detailed thermodynamic and enviro-economic analyses. Mathematical model developed for thermodynamic performance assessment is validated using experiments conducted in inclined solar distillation unit under the climatic condition of Chennai (13.08°N, 80.27°E). Distillation unit produced high quality condensate even from highly saline (40,600 to 60,656 mg/L salinity) feed water. Availability analysis indicated the magnitude of improvement potential, availability destruction, losses and ways for further improvement. Maximum condensate yield, energy and availability efficiency of distillation unit is around 7.09 L/d, 53.45% and 5.39%, respectively for Nellore (one of the east coast locations). Condensate production cost of 18.16 to 32.78 USD/kL and desired availability output of 1.80 to 3.38 kWh/USD invested are observed for the distillation unit at 5.0% interest rate. Maximum yearly average life cycle conversion efficiency, net carbon-dioxide, sulphur-dioxide and nitrous oxide emission alleviated by the unit is around 39.19%, 25.83 tons, 185.73 kg and 75.86 kg, respectively. Viability assessment indicated positive signs for deployment of solar distillation units in 14 locations of coastal India. The proposed solar distillation unit requires lower evaporation area compared to other passive solar distillation units installed in India for the same production capacity. [ABSTRACT FROM AUTHOR]

Due to its lower water requirement, methane emission and soil degradation, a maize–wheat rotation (MWR) may be a more attractive alternative to rice–wheat rotation (RWR), in the upper Indo-Gangetic plains (IGP) of India. However, N2O emission from MWR needs to be quantified to propose management practices for N2O mitigation. A field experiment was conducted at the Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, to assess the impacts of various N sources on N2O emission and its mitigation from the MWR. Six treatments –N0 (control), urea, urea + farmyard manure (FYM), FYM, urea + nitrification inhibitor (NI) and neem oil coated urea (NOCU) were investigated during 2012–2014. Results show ranges of N2O-N emissions from MWR of 0.59–0.69, 1.82–1.86, 1.81–1.85, 1.71–1.77, 1.38–1.52, 1.57–1.61 during 2012–2013, and of 0.62–0.68, 1.86–1.90, 1.78–1.84, 1.72–1.76, 1.40–1.46, 1.52–1.60 during 2013–2014, for N0, urea, urea + FYM, FYM, urea + NI and NOCU treatments, respectively. The 2-year pooled N2O-N emission of MWR decreased by 23% in urea + NI and by 16% in NOCU with higher grain yield as compared to conventional urea application. Application of FYM with urea and FYM alone also reduced N2O-N emission; however, the grain yields of these treatments were decreased. Thus, the study suggests that the application of NOCU and NI with urea can mitigate N2O-N emissions from the maize and wheat crops. Hence, the use of NOCU and application of NI with urea could be a better option to mitigate N2O-N emissions from MWR of the upper IGP of India. [ABSTRACT FROM AUTHOR]

For India, achieving environmental sustainability in the midst of faster growth remains a challenging objective. Therefore, we are revisiting the nature of the Environmental Kuznets Curve (EKC) at different stages of economic growth through both necessary and sufficient conditions under the cubic model specifications in India. Further, we extend the EKC framework by incorporating energy consumption, agricultural value added, trade, the world uncertainty index, and geopolitical risk as additional variables into the three preferred disaggregated greenhouse gas emission (GHG) models. This study employs an auto-regressive distributed lag model (ARDL). The empirical findings show evidence of the valid N-shaped EKC through both necessary and sufficient conditions for carbon dioxide (CO 2) and nitrous oxide (N 2 O) and exhibit the presence of two real and distinct income turning points for both valid EKCs. In contrast, only the necessary condition supports the N-shaped EKC for methane (CH 4) emissions in India. Further, the results highlight that trade has a positive impact, whereas the world uncertainty index has a negative impact on disaggregated GHGs. Similarly, geopolitical risk has a negative effect on CH 4 and N 2 O, whereas energy consumption has a positive impact on CO 2 emissions. Moreover, agricultural value added has a negative effect on CH 4 and a positive effect on N 2 O emissions. Our empirical findings suggest policy recommendations that can collectively work as a roadmap for India to become emission-neutral by 2070. [ABSTRACT FROM AUTHOR]

In the past five decades, nitrous oxide (N 2 O) emissions from Indian agricultural landscapes have significantly increased, making India the fifth-largest emitter of N 2 O globally (∼4.8%). The few studies that evaluated N 2 O at the India scale using a bottom-up approach were constrained to a brief period and employed country-level emission factors (EFs), despite the availability of long-term inventory data and spatially varying EFs. To fill this gap and comprehend the spatio-temporal N 2 O emissions dynamics at the district-level across India, this study created district- and crop-specific N 2 O EFs from 82 field plot studies with 861 observations across 13 locations. Through these improved EFs, district-level emissions were calculated from 1966 to 2017 using a modified IPCC Tier I-Tier II approach (specific EFs for synthetic fertilizer, animal manure, and crop residue return) and highlighted significant spatio-temporal drivers. Total N 2 O emissions in Indian agricultural soils increased from 73.7 ± 3.3 Gg in 1966–279.3 ± 15.8 Gg in 2017. The increase in total N 2 O emissions (3.9 Gg yr−1) from 1966 to 2017 is associated with the increase in crop production (4.1 Tg yr−1) driven by the increase in fertilization (0.3 Tg yr−1). N 2 O emissions from synthetic fertilizer, animal manure, crop residue return, soil organic matter, volatilization, leaching, and runoff increased from 1966 to 2017. On the national scale, N 2 O emissions from synthetic fertilization accounted for 57% in 2017, followed by animal manure (15%) and soil organic matter (9%). While the national emission totals are dominated by synthetic fertilizer application, district-level analyses revealed the possibility of the highest contributions from animal manure, crop residue return, and soil organic matter in 18% of the districts. The overall uncertainty from this modified method and refined EFs was 5.1%. This study is the first to capture long-term N 2 O dynamics at the district scale from Indian agricultural soils. [Display omitted] • Developed district & crop-specific emission factors (EFs) for (in)organic fertilizers. • Overall N 2 O emissions increased concurrently with synthetic fertilizer (1966–2017). • Synthetic fertilizer application drives N 2 O emissions at district & national levels. • Organic fertilizer emissions also dominate at the district level. • Refined EFs (district-scale) caused spatially varying emission patterns. [ABSTRACT FROM AUTHOR]

The estuaries provide the key pathway for travelling carbon across the land-ocean interfaces and behave as both source and sink of greenhouse gases (GHGs) in water-atmosphere systems. The sink-source characteristics of estuaries for GHGs vary spatially. The primary driving factors are adjacent ecologies (agriculture, aquaculture, etc.) and proximities to the sea. To study the sink-source characteristics of estuaries for GHGs (methane (CH 4), nitrous oxide (N 2 O) and carbon dioxide (CO 2)), the water samples were collected from 53 different locations in the estuaries for estimation of dissolved GHGs concentration and air-water GHGs exchanges. The locations represent five zones (Zone I, II, III, IV and V) based on the type and degradation status of mangroves (degraded and undisturbed), anthropogenic activities, and distance from the sea. Zone I, III, V represents to the degraded mangroves far from sea, whereas, Zone II, IV surrounded by undisturbed mangroves and nearer to sea. The average dissolved CH 4 concentrations were higher in the estuaries which were adjacent to degraded mangroves (154.4 nmol L−1) than undisturbed mangroves (81.7 nmol L−1). Further, the average dissolved N 2 O concentrations were 48% higher in the estuaries nearer to degraded mangroves than that of undisturbed ones. Among the degraded mangrove sites, the dissolved CO 2 concentrations were higher at Zone I (30.1 μmol L−1) followed by Zone III and IV, whereas in undisturbed sites, it was higher in Zone IV (22.3 μmol L−1) than Zone II (17.6 μmol L−1). Among the 53 locations, 36, 51 and 33 locations acted as a sink (negative value of exchanges) for CH 4 , N 2 O and CO 2 , respectively. The higher sink potential for CH 4 was recorded to those estuaries adjacent to undisturbed mangroves (−791.69 μmol m−2 d−1) than the degraded ones (−23.18 μmol m−2 d−1). Similarly, the average air-water N 2 O and CO 2 exchanges were more negative in the estuaries which were nearer to undisturbed mangroves indicating higher sink potential. The pH, and salinity of the estuary water were negatively correlated with air-water CH 4 and N 2 O exchanges, whereas those were positively correlated with CO 2 exchanges. Significantly lower dissolved GHGs and air-water GHGs exchange was observed in the estuaries adjacent to the undisturbed mangrove as compared to the degraded mangrove. The reason behind higher sink behaviours of estuaries nearer to undisturbed mangroves are higher intrusion of seawater, less nutrient availability, higher salinity, low carbon contents and alkaline pH compared to estuaries adjacent to degraded mangroves and far from sea. • Dissolved GHGs were higher in the estuaries adjacent to degraded mangroves. • Majority of locations in the estuaries acted as a sink for GHGs. • The estuaries adjacent to undisturbed mangroves acted as better sink for GHGs exchanges. [ABSTRACT FROM AUTHOR]

This study presents detailed crop and gas flux data from two years of rice production at the experimental farm of the ICAR-Indian Agricultural Research Institute, New Delhi, India. In comparing 4 nitrogen (N) fertiliser regimes across 4 rice cultivars (CRD 310, IR-64, MTU 1010, P-44), we have added to growing evidence of the environmental costs of rice production in the region. The study shows that rice cultivar can impact yields of both grain, and total biomass produced in given circumstances, with the CRD 310 cultivar showing consistently high nitrogen use efficiency (NUE) for total biomass compared with other tested varieties, but not necessarily with the highest grain yield, which was P-44 in this experiment. While NUE of the rice did vary depending on experimental treatments (ranging from 41% to 73%), 73%), this did not translate directly into the reduction of emissions of ammonia (NH 3) and nitrous oxide (N 2 O). Emissions were relatively similar across the different rice cultivars regardless of NUE. Conversely, agronomic practices that reduced total N losses were associated with higher yield. In terms of fertiliser application, the outstanding impact was of the very high methane (CH 4) emissions as a result of incorporating farmyard manure (FYM) into rice paddies, which dominated the overall effect on global warming potential. While the use of nitrification and urease inhibiting substances decreased N 2 O emissions overall, NH 3 emissions were relatively unaffected (or slightly higher). Overall, the greatest reduction in greenhouse gas (GHG) emissions came from reducing irrigation water added to the fields, resulting in higher N 2 O, but significantly less CH 4 emissions, reducing net GHG emission compared with continuous flooding. Overall, genetic differences generated more variation in yield and NUE than agronomic management (excluding controls), whereas agronomy generated larger differences than genetics concerning gaseous losses. This study suggests that a mixed approach needs to be applied when attempting to reduce pollution and global warming potential from rice production and potential pollution swapping and synergies need to be considered. Finding the right balance of rice cultivar, irrigation technique and fertiliser type could significantly reduce emissions, while getting it wrong can result in considerably poorer yields and higher pollution. • Both genetic and agronomic solutions have similar potential to improve yield and NUE. • Co-application of nitrification and urease inhibitor reduced N 2 O emissions. • Decreasing irrigation resulted in less methane emission, but increased nitrogen pollution. • Rice genetics had no significant effect on the gaseous emissions. [ABSTRACT FROM AUTHOR]

Cropland–based agricultural activities emit 34.13% of the total non-carbon dioxide emission in India as of 2007 and contribute 63% of the gross value added from agriculture as of 2014–15. It accounts for 24.17% of the India's total methane and 95.84% of the total nitrous oxide emission from agricultural sector. This article analyzes the change in non-carbon dioxide greenhouse gases emission overtime from India's cropland based agricultural activities for the period of 1980–81 to 2014–15 and uses Logarithmic Mean Divisia Index to identify the factors that are driving this emission change. Results show that during the study period methane emission from paddy cultivation declines at statistically insignificant rate of 200 tonnes per year whereas nitrous oxide emission from nitrogen-fertilizer use increases by approximately 358%, growing at a statistically significant rate of 5100 tonnes per year. Fertilizer intensity contributes 48% in the growth of non-carbon dioxide greenhouse gases emission from cropland based agricultural activities followed by affluence and population growth. On the contrary structural change of the economy with declining relative contribution of agriculture in national gross domestic product, improved productivity of fertilizer use, declining cultivated land per unit of agricultural output and declining emission intensity are helping to reduce emission. Empirical analysis clearly show link between fertilizer policy intervention and nitrous oxide emissions indicating role of policy as an important driver in managing non-carbon dioxide emission from India's cropland–based agricultural activities. • Methane emission from paddy fields in India declined marginally during 1980–2015. • Years when yield from fertilizer use increased non-CO 2 emission came down. • Fertilizer policy led to unbalanced use of N-fertilizer increasing N 2 O emission. • Intensive agricultural practices in India are pulling down non-CO 2 emission. [ABSTRACT FROM AUTHOR]

Context: Anxiety and fear of pain are the two major deterrents for which patients avoid dental treatment. Local anesthetic, which forms the foundation for the delivery of pain-free endodontic treatment, does not serve the purpose in anxious patients and requires augmentation with other pharmacological agents. Aims: The aim of this study is to observe the effectiveness of nitrous oxide in alleviating patient anxiety and pain during endodontic treatment of a vital tooth. Settings and Design: The present in vivo study was conducted on sixty healthy patients from the Outpatient Department of Genesis Institute of Dental Sciences and Research, Ferozepur, Punjab, India. Subjects and Methods: Sixty anxious patients having irreversible pulpitis in their lower molar were selected and divided into two groups, namely control group and intervention group, with thirty patients placed in each group. In control group, access opening and pulp extirpation was done under local anesthesia only, whereas in intervention group, access opening and pulp extirpation was done under local anesthesia and nitrous oxide sedation. The anxiety levels of patients, before and after the treatment, were measured using the Modified Dental Anxiety Scale. Pain felt by the patients during administration of local anesthesia and during access opening was measured using the Visual Analog Scale. Statistical Analysis Used: The data were analyzed using ANOVA and paired t-test, and graphical analysis of the data was done. Results: Significant reduction in anxiety and pain levels of patients during endodontic access opening including significant reduction in pain during administration of local anesthesia was observed under nitrous oxide sedation. Conclusions: Conscious sedation with nitrous oxide is a useful technique to add to the armamentarium used in the treatment of teeth with symptomatic irreversible pulpitis. [ABSTRACT FROM AUTHOR]

• Denitrification in the Western Indian continental shelf (WICS) waters during late summer monsoon was sulphide-driven, occurred at the mean rate of 2.69 µM N 2 d−1, outcompeted chemoorganotrophic denitrification by 2-8 times and intensified the N loss. • Detection of S0 plume through satellite imagery, stimulation of N 2 and N 2 O production by sulphide, and consumption of NO x − and S2− at a ratio close to the theoretical value suggested the denitrification being carried out by chemolithoautotrophs. • High N 2 O production in the sulphide-spiked 15N incubations suggested that the autotrophic denitrification was the prime reason behind high N 2 O accumulation at the pelagic chemocline during late summer monsoon. • The chemoautotrophic dark CO 2 fixation (0.21 g C m−2 d−1) was ∼18% of the photoautotrophic production and accounted for ∼15% of the total column productivity. • The chemolithoautotrophic denitrification rate over the WICS was the second highest among the anoxic coastal systems of the world, and accounted for the net removal of 0.4 Tg of fixed N and 0.57 Tg of sulphide, and fixation of 0.1 Tg of CO 2 annually. The Eastern Arabian Sea Shelf i.e. Western Indian Continental Shelf (WICS) – a known biogeochemical hotspot is characterized by monsoonal upwelling, seasonal O 2 deficiency, extremely high N 2 O build-up and sulphidic events. The frequency and duration of the sulphidic events have increased over the last two decades, but their impact on the pelagic N cycling, N budget, and N 2 O dynamics is poorly constrained. Thus, to address these problems and assess their implications on WICS biogeochemistry, we carried out physico-chemical measurements, 15N-labeled incubations and bag incubations on five transects over the shelf during the sulphidic event (September-October) of 2011. We observed very high rates of sulphide-driven chemolithotrophic denitrification (1885–5825 nM N 2 d−1) in the sulphidic, nitrate-depleted waters, and its potential occurrence in the sulphide-free, nitrate-replete waters (460–3137 nM N 2 d−1), along with high transient N 2 O production, and comparably low rates of anammox (0–119 nM N 2 d−1) and DNRA (0–45 nM N d−1). Despite the predominant cloud cover during the monsoon season, we could for the first time show the satellite image of a large colloidal sulphur (S0) plume associated with the sulphidic event off Western India providing further evidence of extensive sulphide oxidation coupled to denitrification. Sulphide-driven denitrification (mean rate = 2697 nM N 2 d−1) appeared to be the dominant N loss process during the anoxic regime (September-October) replacing the chemoorganotrophic (i.e. heterotrophic) denitrification (342 nM N 2 d−1) that predominates during the preceding suboxic regime (July-August). Overall, the highest sulphide-driven denitrification rate over the WICS was found to be the second highest among the anoxic coastal systems of the world. Furthermore, simultaneous consumption of NO x − and S2− at a ratio close to the theoretical value in the anaerobic incubations of chemocline waters indicated that the sulphide-driven denitrifiers were fixing carbon. The estimated dark C production (0.21 g C m−2 d−1) due to chemolithoautotrophic denitrification was 18% of the photoautotrophic production and accounted for 15% of the total column productivity. Based on our conservative estimates, the chemolithoautotrophic denitrification was responsible for the removal of 0.4 Tg of fixed N and 0.57 Tg of sulphide, and fixation of 0.1 Tg of carbon annually in the shelf waters. Thus, the sulphidic event impacted the biogeochemistry and ecology, and modulated the N loss pathways and rates over the WICS. With the expansion and intensification of OMZs induced by global climate change, and the spreading of dead zones due to increasing anthropogenic activities, chemolithoautotrophic denitrification is likely to become increasingly significant in oceanic N cycle and impact the N budgets of shallow marine systems particularly. [ABSTRACT FROM AUTHOR]

The fate of the enormous amount of reactive nitrogen released to the environment by human activities in India is unknown. Here we show occurrence of seasonal stratification and generally low concentrations of dissolved inorganic combined nitrogen, and high molecular nitrogen (N2) to argon ratio, thus suggesting seasonal loss to N2 in anoxic hypolimnia of several dam-reservoirs. However, 15N-experiments yielded low rates of denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium--except in the presence of methane (CH4) that caused ~12-fold increase in denitrification. While nitrite-dependent anaerobic methanotrophs belonging to the NC10 phylum were present, previously considered aerobic methanotrophs were far more abundant (up to 13.9%) in anoxic hypolimnion. Methane accumulation in anoxic freshwater systems seems to facilitate rapid loss of reactive nitrogen, with generally low production of nitrous oxide (N2O), through widespread coupling between methanotrophy and denitrification, potentially mitigating eutrophication and emissions of CH4 and N2O to the atmosphere. [ABSTRACT FROM AUTHOR]

Rice ( Oryza sativa L.) production is facing major challenges, including scarcity of irrigation water and ongoing climate change. Modifications of the current cropping techniques could increase yield, save water, and mitigate greenhouse gas emission. We investigated the effect of planting methods (young seedlings, wide spacing with alternate wetting and drying irrigation [YW-AWD], old seedlings, narrow spacing with continuous flooding [ON-CF], and in-between the two planting methods [IB-AWD]) and rice varieties on methane (CH 4 ) and (N 2 O) emissions during two crop seasons. The results show that CH 4 emission, averaged over rice varieties, reduced for YW-AWD by 41% and 24%, compared with ON-CF, while the reduction in emission for the IB-AWD method was 48% and 26% in summer (dry) and monsoon (wet) season, respectively. However, an increase in N 2 O emission was observed for YW-AWD and IB-AWD methods in both seasons. There was no significant difference in CH 4 and N 2 O emissions between the tested varieties. The total water saving under YW-AWD and IB-AWD was 47.5% and 49.3% in summer, and 79.4% and 79.8% in monsoon season, respectively, compared with ON-CF. The grain yields of YW-AWD and IB-AWD were comparable with the yield of ON-CF in both seasons. The CO 2 -eq emission and yield-scaled CO 2 -eq emission from YW-AWD and IB-AWD were significantly lower compared with ON CF due to low CH 4 emission, while maintaining similar rice yields. This study showed that the YW-AWD and IB-AWD methods are effective in reducing CO 2 -eq emission and saving irrigation water, while maintaining the rice yield. [ABSTRACT FROM AUTHOR]

The potential effects of tidal and diel cycles on fluxes and concentrations of carbon dioxide (pCO 2), methane (CH 4), and nitrous oxide (N 2 O) along with associated biogeochemical processes remain poorly understood in tropical estuaries. The present study, based on six-hourly sampling for nine consecutive days at three locations along the salinity gradient in the Mahanadi estuary of India, revealed that the tidal forcing affected pCO 2 and CH 4 in the mixing zone with elevated concentrations during low tide with maximum concentrations up to 21,606 μatm and 285 μM, respectively. pCO 2 increased with decrease in tidal height within low and high tide duration as well, possibly due to higher relative contribution of freshwater with high CO 2. N 2 O, on the other hand, showed no significant variability with tidal cycle or water level fluctuation during high and low tide. Barring the offshore region, the study area was source of greenhouse gases to the atmosphere. • Tidal cycle and fluxes of greenhouse gases in the estuary were coupled. • CO 2 and CH 4 fluxes were high during low tide. • N 2 O distribution did not change significantly with tide. • Largely, the estuary was source for greenhouse gases to the atmosphere. [ABSTRACT FROM AUTHOR]

Agricultural activities emit substantial amounts of methane (CH4) and nitrous oxides (N2O), the two important greenhouse gases (GHG) with high global warming potentials (GWP). So far, many studies have already been carried out at national and state level, but lack micro-level (district or block-level) inventory in India. The present study sheds light on the flux of CH4 and N2O (from all possible sources) from agricultural soil of various blocks in the Murshidabad district, based on the inventory prepared, using the IPCC methodology, with adjusted emission factors and coefficients appropriate for the local level. The economy of the Murshidabad district almost completely rests on agriculture as more than 80 per cent of the population is directly or indirectly dependent on it for their livelihood. Paddy is the dominating crop, cultivated on more than 60 per cent of the gross cropped area. The present work is based on the review of various literature and reports collected from respective state government offices and websites. Results show that CH4 and N2O emission from the agricultural fields are 126.405 Gg and 0.652 Gg respectively for the year 2011−12 with a large scale spatial variation (block-level) within the district. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore in the rabi season in order to assess the sustainability of SRI in changing climate. Three aspects of rice cultivation, GHG emission, water use, and Energy consumption were accounted to vindicate the sustainability of SRI over other cultivation systems. Three rice cultivation systems SRI (System of Rice Intensification), AWD(Alternate Wetting and Drying) and conventional were selected which differ in agronomic and water management practices. CH4, N2O and CO2 gas emissions from field were collected using static closed chamber and was analyzed using a gas chromatograph equipped with FID. Water irrigated to the field was measured in m3 using a water meter. The results showed that SRI method of cultivation recorded less GHG emissions and water use with higher yield. Alternate wetting and drying method of water management reduced methane emission in AWD by 41 per cent and SRI by 44.3 per cent when compared with conventional system. [ABSTRACT FROM AUTHOR]

An investigation to assess the greenhouse gases (GHG's) fluxes in rice cultivation under current and elevated temperature was carried out at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore, during rabi season (November 2014 - March 2015). This experimentation was carried out with two temperature levels viz., current temperature at open environment and +2°C elevated temperature at Temperature Controlled Chamber. During the experimentation, GHG emission rate was evaluated. The nitrous oxide emission attained maximum at 15 DAT followed by 45 DAT and then decreased towards maturity. The methane emission rates increased with age of the crop, but attained maximum at harvesting stage. The methane emission rates from rice crop grown under open environment were higher than elevated temperature. The nitrous oxide emission rates from rice crop grown under +2°C elevated were higher than open environment. Methane is normally translocated through rice plants and the higher biomass generation under open environment led to higher methane translocation. The nitrous oxide emission was normally through microbial activity and the higher microbial activity was in elevated temperature led to more nitrous oxide emission. The tradeoff between CH4 and N2O emission has to be analyzed critically and developing appropriate nutrient and water management strategies and maintaining the soil redox potential at an intermediate range (-100 to +200 mV) would minimize emissions of both CH4 and N2O. Overall, the data have shown clear evidence that rice cultivation in future reduced methane emission but increase nitrous oxide emission. [ABSTRACT FROM AUTHOR]

Field trials were conducted in Haryana representing the northwestern Indo-Gangetic Plains (IGP) to assess the changes brought about by management, including conservation agriculture (CA) practices, in the global warming potential (GWP) of conventional rice–wheat systems. Conservation agriculture is an approach to managing agro-ecosystems for improved and sustained productivity, by way of minimal soil disturbance, permanent soil cover with organic matter or cover crops and crop rotation. Methane (CH 4 ) and nitrous oxide (N 2 O) fluxes were measured using static chambers. Experiments involved four cropping system scenarios with different CA components, and different N rates. In addition, emissions of CH 4 and N 2 O fluxes were measured in farmers’ fields to establish baselines. The dynamics of CH 4 emissions were controlled by floodwater levels, and fertilizer N had no effect. On the other hand, N application rates and timing in relation to soil water status determined the N 2 O emissions in rice fields. Nitrous oxide fluxes could be avoided by applying N fertilizer to wet soil or by irrigating the field not later than 1 day after N application. Applying crop residues on soil surface had no significant effect on the seasonal CH 4 and N 2 O emissions. It was estimated that switching rice crop establishment method from conventional to CA-based practices in Haryana could reduce GWP for rice by 23% or by 1.26 Tg CO 2 eq yr −1 . An intensive CA-based rice–wheat and maize–wheat system reduced GWP by 16–26% or by 1.3–2.0 Tg CO 2 eq yr −1 compared with the conventional rice–wheat system. However, this reduction in GWP would be from a decrease in diesel and electricity consumption and not from direct emissions of CH 4 and N 2 O, which were higher in the maize–wheat system than in the rice–wheat system. [ABSTRACT FROM AUTHOR]

Quantification of greenhouse gases (GHGs) emissions from agriculture is necessary to prepare the national inventories and to develop the mitigation strategies. Field experiments were conducted during 2008–2010 at the experimental farm of the Indian Agricultural Research Institute, New Delhi, India to quantify nitrous oxide (N 2 O), methane (CH 4 ), and carbon dioxide (CO 2 ) emissions from soils under cereals, pulses, millets, and oilseed crops. Total cumulative N 2 O emissions were significantly different (P > 0.05) among the crop types. Emission of N 2 O as percentage of applied N was the highest in pulses (0.67%) followed by oilseeds (0.55%), millets (0.43%) and cereals (0.40%). The emission increased with increasing rate of N application (r 2 = 0.74, P < 0.05). The cumulative flux of CH 4 from the rice crop was 28.64 ± 4.40 kg ha − 1 , while the mean seasonal integrated flux of CO 2 from soils ranged from 3058 ± 236 to 3616 ± 157 kg CO 2 ha − 1 under different crops. The global warming potential (GWP) of crops varied between 3053 kg CO 2 eq. ha − 1 (pigeon pea) and 3968 kg CO 2 eq. ha − 1 (wheat). The carbon equivalent emission (CEE) was least in pigeon pea (833 kg C ha − 1 ) and largest in wheat (1042 kg C ha − 1 ). The GWP per unit of economic yield was the highest in pulses and the lowest in cereal crops. The uncertainties in emission values varied from 4.6 to 22.0%. These emission values will be useful in updating the GHGs emission inventory of Indian agriculture. [ABSTRACT FROM AUTHOR]

We have studied the seasonal and tidal variation of methane (CH 4 ) and nitrous oxide (N 2 O) emission from the intertidal sediment of Bhitarkanika mangrove in the east coast of India. Seasonal variability study was conducted at five sites (three replicate of each site) inside the core area of the national park during three different seasons (summer, monsoon and winter) whereas tidal variation was studied at three different sites outside the core area during monsoon and winter season. Both CH 4 and N 2 O emission from the intertidal sediment were significantly higher under the low tide condition during the winter season. During the study period CH 4 emission from five different sites was ranged between 0.08 and 2.30 mg m −2 h −1 and the N 2 O emission was ranged between 9.0 and 187.58 μg m −2 h −1 . Average seasonal N 2 O emission (μg m −2 h −1 ) from five different sites followed the order: winter (115.60 ± 21.90) > summer (45.29 ± 7.78) > monsoon (16.98 ± 2.54). CH 4 and N 2 O emission was also recorded significantly higher during the winter season over the tidal cycle of three sampling locations. The CH 4 emission was negatively correlated with sediment salinity (r = −0.91, P < 0.05) and SO 4 –2 (r = −0.89, P < 0.05) concentration whereas; the N 2 O emission was positively correlated with sediment salinity (r = 0.48) and NO 3 − –N (r = 0.88, P < 0.05) concentration during the monsoon season. Positive correlation of N 2 O emission with the sediment NO 3 − –N indicates possible influence of upstream anthropogenic activities on N 2 O emission from the mangrove sediment. In general, methylamine utilizing methanogen and denitrifying bacterial population was significantly higher during winter season in the mangrove sediment. The study concludes that the CH 4 and N 2 O emission from the sediment at different sites during different seasons are influenced by allochthonous carbon and nitrogenous materials. [ABSTRACT FROM AUTHOR]

A field experiment was carried out at the farm of Indian Agricultural Research Institute, New Delhi to quantify the effect of elevated carbon dioxide (CO2) and different levels of N fertiliser application on nitrous oxide (N2O) and carbon dioxide (CO2) emissions from soil under maize. The experiment included five treatments: 60 kg N ha−1 under ambient CO2 (385 ppm) in open plots, 120 kg N ha−1 under ambient CO2 (385 ppm) in open plots, 160 kg N ha−1 under ambient CO2 (385 ppm) in open plots, 120 kg N ha−1 under ambient CO2 (385 ppm) in open top chambers (OTC) and 120 kg N ha−1 under elevated CO2 (500 ± 50 ppm) in the OTC. Peaks of N2O flux were observed after every dose of N application. Cumulative N2O emission was 13% lower under ambient CO2 as compared to the elevated CO2 concentrations. There was an increase in CO2 emissions with application of N from 60 kg ha−1 to 160 kg ha−1. Higher yield and root biomass was observed under higher N treatment (160 kg N ha−1). There was no significant increase in maize yield under elevated CO2 as compared to ambient CO2. The carbon emitted was more than the carbon fixed under elevated CO2 as compared to ambient CO2 levels. The carbon efficiency ratio (C fixed/C emitted) was highest in ambient CO2 treatment in the OTC. [ABSTRACT FROM AUTHOR]

Agricultural soils contribute toward the emission of methane (CH4) and nitrous oxide (N2O), the two important greenhouse gases (GHGs) causing global warming. A state-wise inventory of CH4 and N2O emissions from agricultural soils of India was prepared for the base year 2007 using the Intergovernmental Panel on Climate Change (IPCC) national inventory preparation guidelines. For CH4 inventory, state-specific emission coefficients were used for rice grown under upland, rain-fed, irrigated, and deepwater, the four major rice ecosystems of the country. In case of N2O, both direct and indirect emissions from agricultural soils in different states were calculated using indigenous country specific emission factors. The change in annual emission of CH4 and N2O during the period 1980 to 2007 was estimated using the same emission coefficients. Indian rice fields covering an area of 43.86 million ha under the different rice ecosystems emitted 3.37 million tons of CH4 (84.25 Tg CO2 equivalents) in 2007. The annual direct and indirect N2O-N emissions from Indian agricultural soils was estimated to be 118.67 Gg (55.5 Tg CO2 equivalent) and 19.48 Gg (9.1 Tg CO2 equivalent), respectively. The global warming potential of the agricultural soils was estimated to be 148 Tg for the year 2007. Emissions from field burning of agricultural residues resulted in an annual emission of 250 Gg of CH4 (6.2 Tg CO2 equivalent) and 6.5 Gg of N2O (1.9 Tg CO2 equivalent). Emission of CH4 from Indian rice fields has remained almost constant during this period whereas there has been an increase of 176% in N2O emissions from agricultural soils due to increased inorganic fertilizer application, however the greenhouse gas emission intensity has declined over the years due to increase in food production. [ABSTRACT FROM AUTHOR]

A study on biogeochemical cycling in the west coastal Bay of Bengal was undertaken during the peak discharge period to understand the influence of enhanced stratification and primary production on the possible intensification of the oxygen minimum zone (OMZ). Our study reveals that oxygen concentrations were below the detection limits in the northwestern (NW) coastal Bay of Bengal between 100 and 500 m associated with strong stratification and high phytoplankton biomass. Such low oxygen concentrations have never been reported so far from the coastal Bay of Bengal. Despite the existence of an environment conducive to denitrification in the coastal Bay of Bengal, accumulation of neither secondary nitrite nor nitrous oxide (NO) was observed. The absence of denitrification was reported to be caused by faster scavenging of organic matter and low bacterial respiration rates; in contrast, our results suggest that neither of these factors are potential reasons for the absence of denitrification in the coastal Bay of Bengal. [ABSTRACT FROM AUTHOR]

Estuaries are known to contribute a significant amount of nitrous oxide (N2O) to the atmosphere; however, the contribution from the Indian estuaries is unknown. We made an attempt to estimate emissions of N2O from the Indian estuaries by collecting samples from 28 major and minor estuaries along the Indian coast during the wet and dry periods. The N2O was mostly saturated in all measured Indian estuaries during the study period (72-631%), with exceptionally high saturation in the Ponniyaar estuary (5902%) during the wet period. The N2O saturation displayed a strong relation with dissolved inorganic nitrogen (DIN; nitrate +nitrite and ammonium), ammonium and dissolved oxygen saturation, suggesting that nitrification is the major source of N2O in the Indian estuaries. The negative relation between salinity and N2O saturation suggests inner estuaries are a strong source compared to outer estuaries. The annual mean N2O saturation (204±137%) and fluxes (1.3 µmol N2O m-2 d-1) in the Indian estuaries were significantly less than European estuaries (271% and ~2.7 µmol N2O m-2 d-1, respectively). The estimation of flux of N2O from the European estuaries was also biased due to the inclusion of an exceptionally high supersaturation value from a small UK estuary, Colne (2645%). However, low N2O saturation and fluxes in the Indian estuaries were related to mean low concentration of DIN that led to low nitrification rates compared to world estuaries. Despite India ranking second in artificial fertilizers use, high flushing rates during the wet period reduce residence time leading to less modification within the estuary. [ABSTRACT FROM AUTHOR]

Dynamics of nitrous oxide (N2O) emission and the relationship of soil properties with N2O emission were studied from the tea ecosystem of North East India situated at north bank plain agroclimatic zone at Tezpur, Assam. The gas samples were collected from the tea bush at weekly intervals from 30 August 2008. Our results shows that N2O fluxes from the tea garden planted with varieties Hilika and TV-23 ranged from 7.51 to 63.30 µg N2O-N m-2 h-1. Seasonal N2O emission from Hilika and TV-23 was 46.13 and 55.17 mg N2ON m-2 respectively. N2O emission showed a relationship with soil moisture, soil temperature and soil NO-3-N of the experimental field. Soil moisture and soil temperature were found to be the main variables influencing N2O emission from the tea ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: Emission inventory of CO2, CH4, N2O and SO2 has been prepared for Nagpur city in Central India for the year 2004. Data on fossil fuel (coal, light diesel oil, high speed diesel, petrol/gasoline, low sulphur heavy stock, furnace oil and kerosene) consumption in thermal power, industrial, transport and domestic sectors were collected. Thermal power sector had the maximum coal consumption followed by the industrial and domestic sectors, whereas kerosene, liquefied petroleum gas (LPG), diesel and gasoline were used only in any single sector. Total annual CO2, CH4, N2O and SO2 emissions from these fuels in Nagpur city for the year 2004 was found to be 14792418 MT (14.8 Tg), 4649 (4.6 Tg), 1529 (1.5 Tg) and 69093 (6.9 Tg), respectively, in which thermal power and domestic sector had the maximum share. Coal was found to be the major contributor to Green House Gas (GHG) and SO2 emissions in all the sectors barring transport and domestic sectors. Carbon dioxide was the predominant GHG emitted by the selected sectors in terms of absolute emissions and also global warming contribution (GWC), though the share in the latter was lesser in magnitude due to higher global warming potential (GWP) of CH4 and N2O than CO2. Thermal power sector had a share of 51% in total CO2 emissions from all the sectors, followed by domestic, industrial and transport sectors having 27, 12 and 10% contributions, respectively. Share of thermal power sector in total SO2 emissions was 61%, followed by 24% from industrial, 10% from domestic and 5% from transport sector. [Copyright &y& Elsevier]

Recent market slump in rice, less rainfall during monsoon, high temperature and scarcity of water during dry season leads to lower grain yield and less profit from rice cultivation in India. Farmers' grow upland crops like chickpea ( Cicer arietinum), greengram ( Vigna radiate), mustard ( Brassica nigra), corn ( Zea maize), pigeonpea ( Cajanus cajan), potato ( Solanum tuberosum), sunflower ( Helianthus annuus) etc. along with rice ( Oryza sativa) during the dry season. However, knowledge of greenhouse gas (GHG) emission from these rice based cropping systems is very limited. In the present study four rice based cropping systems was studied along with rice-rice rotation system as control in respect of GHG emission, yield potential and economic feasibility. Conventional plantation and fertilizer application methodology was followed for each crop. Methane (CH) and nitrous oxide (NO) flux from field plots were studied with conventional closed chamber method using gas chromatograph. CH flux was recorded highest from rice-rice rotation plots (304.25 kg ha). NO flux was recorded 1.02 kg ha from rice-rice rotation system during wet season. However, during wet season, higher NO flux (1.93 kg ha) was recorded from rice-potato-sesame rotation plots. Annual NO flux was also recorded significantly low (3.42 kg ha) from rice-rice rotation plots and high (6.19 kg ha) from rice-chickpea-greengram rotation plots. Significantly lower annual grain yield was recorded from rice-rice rotation plots (9.25 Mg ha) whereas it was 18.84 Mg rice eq ha from rice-potato-sesame rotation system. The global warming potential (GWP) of rice-rice rotation system was recorded significantly high (8.62 Mg CO ha) compare to plots with different rice based cropping systems. Computing all C-emission from cradle-to-grave, highest total C-cost was recorded from the rice-rice rotation system ($62.00 ha). We have made an attempt to calculate the C-credit of different rice based cropping systems by considering the difference of C-cost with control. The study suggests that the rice-potato-sesame is most sustainable among different cropping system studied in terms of economic profit ($1248.21 ha) and C-credit ($38.60 ha). The result of the study may be limited to the study region; however, the study has potential use in respect to the development of agriculture practice for adaptation to climate change. [ABSTRACT FROM AUTHOR]

Synthetic nitrogen (N) fertilizers, by both very energy-intensive manufacture and inefficient N use in farm soils, contribute rationally to emissions of greenhouse gases (GHGs) and, thus, climate change. India consumes ∼14Mt of synthetic N per year, of which about 80 per cent is produced, and is the second-largest producer and consumer in the world, after China. We estimate that GHG emissions from synthetic N fertilizer in India reached ∼100Mt of carbon dioxide equivalent (CO2-e) in 2006/2007; about half of these emissions resulted from the 11Mt of synthetic N produced in the country that year (48Mt of CO2-e) and the other half resulted from the 14Mt of N applied to Indian farm soils in the same year (51 Mt of CO2-e, ranging between 28 and 163Mt of CO2-e). Emissions from synthetic N fertilizers represent 6 per cent of India's total anthropogenic emissions, comparable to cement industry and to the whole road transport system. There is significant potential to mitigate these emissions: savings from increased N use efficiency and from shifting away from synthetic fertilizer could reduce total fertilizers emissions to 37Mt of CO2-e, and the contribution of fertilizers to India's emissions would drop from 6 to 2 per cent. [ABSTRACT FROM AUTHOR]

In view of the depleting availability of water for agriculture, higher emission of nitrous oxide and methane from low land rice cultivation and their deleterious impact on global warming phenomenon, the present study stressed the need for cultivation of aerobic rice. The study focuses on identifying and mapping suitable sites in eastern India through computation of rice aridity index from soils and climatic data and proposing suitability criteria model and assessing potential yield. This study gains further significance since aerobic rice cultivation could improve the upland production efficiency and helps reduction of greenhouse gases. [ABSTRACT FROM AUTHOR]

The article presents a study on the net nitrous oxide production and denitrification activity at two mangrove ecosystems in Goa, India. The study involves stratified sampling at 2-centimeter (cm) intervals within the 0- to 10-cm depth range, elevated denitrification activity at Divar Island in Goa, and detailed investigations on the major pathway that contributes to the production of N2O performed at the pristine site Tuvem in Goa. Furthermore, the result shows that nitrous oxide production rates are closely correlated to nitrite concentration and denitrifier abundance, which suggests that N2O production is caused by nitrite utilization by microbial activity.

Abstract: No-till farming in wheat is being practiced in the rice–wheat system of the Indo-Gangetic plains of south Asia for resource conservation. No-tillage leads to mitigation of carbon dioxide emission, but may emit more nitrous oxide (N2O) as compared to conventional tillage reducing mitigation benefit. The aim of this study was assessment of N2O emission in wheat grown under conventional and no-tillage and its mitigation using two new nitrification inhibitors, viz. S-benzylisothiouronium butanoate (SBT-butanoate) and S-benzylisothiouronium furoate (SBT-furoate). Cumulative emission of N2O-N was higher under no-tillage by 12.2% with urea fertilization and from 4.1 to 4.8% for the inhibitor treatments as compared to the conventional tillage. In no-tillage total emission of N2O-N reduced from 0.43% of applied N with urea to 0.29% of applied N with SBT-furoate treatment. The N2O-N emissions in SBT-butanoate treatment were at par with the standard dicyandiamide (DCD) inhibitor treatment. Water-filled pore space (WFPS) was higher on most days under no-tillage, with the largest emissions (>1000μgN2O-Nm−2 day−1) coming with nitrification of ammonium-N present in soil below 60% WFPS. Carbon efficiency ratio was highest (48.1) from SBT-furoate treatment under conventional tillage. The nitrification inhibitors used in the study increased yield of wheat, reduced global warming potential by 8.9–19.5% over urea treatment and may be used to mitigate N2O emission. [Copyright &y& Elsevier]

An assessment of coastal pollution was made on the basis of trace element concentrations (arsenic — As, mercury — Hg) in the Gulf of Mannar. The beachrock samples were collected along the coastal tracts between Rameswaram and Kanyakumari. The samples were dried and digested to determine the As and Hg using atomic absorption spectrophotometer (AAS-air-acetylene and nitrous oxide method). The As and Hg accumulation status of the beachrock was assessed using geo-accumulation index values ( Igeo). The accumulation of As and Hg in the beachrock ranges from 2.75 to 20.72 μg g−1 and from 0.06 to 0.31 μg g−1, respectively. The As and Hg concentrations in the beachrocks are compared with crustal average values and average of other region sediments. The possible source of the contamination is from atmospheric deposition and anthropogenic activities. [ABSTRACT FROM AUTHOR]

We measured dissolved N2O, CH4, O2, , and on 7 transects along the polluted Adyar River–estuary, SE India and estimated N2O and CH4 emissions using a gas exchange relation and a floating chamber. High implied some nitrification of a large anthropogenic pool. In the lower catchment CH4 was maximal (6.3±4.3×104 nM), exceeding the ebullition threshold, whereas strong undersaturation of N2O and O2 implied intense denitrification. Emissions fluxes for the whole Adyar system ∼2.5×108 gCH4 yr−1 and ∼2.4×106 gN2Oyr−1 estimated with a gas exchange relation and ∼2×109 gCH4 yr−1 derived with a floating chamber illustrate the importance of CH4 ebullition. An equivalent CO2 flux ∼1–10×1010 gyr−1 derived using global warming potentials is equivalent to total Chennai motor vehicle CO2 emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements. [Copyright &y& Elsevier]

Mangroves are considered to be a minor source of greenhouse gases (CH4 and N2O) in pristine environmental condition. However, estimates of efflux suggest that anthropogenic activities have led to a pronounced increase in greenhouse gas emission. Along the east coast of India, mangroves vary substantially in area, physiography and freshwater input, which ultimately modify the biogeochemical processes operating within this ecosystem. An attempt has here been made to elucidate the existing variation and role of climatic variability on the emission of greenhouse gases from mangroves. The flux estimates of CH4 and N2O have been quantified from Bhitarkanika mangrove accounting for spatial and temporal (seasonal) variation. The annual rates were estimated to be 0.096 × 10 9 g CH4 year−1 and 5.8 × 103g N2O year−1 for the whole mangrove area of the east coast of India. Upscaling these estimates yield an annual emission of 1.95 × 10 12 g CH4 year−1 and 1.1 × 10 11 g N2O year−1 from worldwide mangrove areas. The influence of elevated nutrient inputs through anthropogenic influence enhances the emission of greenhouse gas. The present article shows the need to develop an inventory on greenhouse gas flux from mangrove ecosystem. [ABSTRACT FROM AUTHOR]

Intermittent flooding (IF) of rice has been encouraged as an approach to reduce water use and methane emissions compared with continuous flooding (CF), but may involve trade-offs. This study compared the contrasting effect of IF and CF flooding regimes on emissions of methane (CH 4), nitrous oxide (N 2 O) and ammonia (NH 3), nitrogen use efficiency (NUE) and yield. A split plot design was used which assessed the effects of four different fertiliser types. The results suggest that converting from CF to IF irrigation does lower CH 4 emissions (by approximately 18%); however, this comes at a cost. IF irrigation resulted in a significant decrease in grain yield, regardless of fertiliser type (6.1% in this study) and also a significant decrease in NUE (a drop of 22.5% when compared to CF). IF irrigation also resulted in a small, but statistically significant (t -test p < 0.01) increase in N 2 O emissions. Difference in NH 3 emission between the flooding regimes was not statistically significant. Our study concludes that conversion from CF to IF irrigation methods may well reduce overall global warming potential of greenhouse gas emissions from rice production; however, yield penalties and nitrogen pollution are likely to increase as a result. Leaf colour chart based application of Neem coated urea may lower the yield scaled GHG emissions under CF irrigation and NH 3 loss in IF irrigation. • Intermittent flooding (IF) irrigation lowers CH 4 emissions by approximately 18%. • Highest harvest NUE (64.5%) was in LCC based N with Continuous flooding irrigation. • LCC based N application lowered Yield scaled-GWP in CF and NH 3 loss in IF. • IF resulted in trade-off between reduced GWP and yield penalty. [ABSTRACT FROM AUTHOR]

Fluxes of greenhouse gases, CH4 and N2O, were measured from a mangrove ecosystem of the Cauvery delta (Muthupet) in South India. CH4 emissions were in the range between 18.99 and 37.53 mg/sq. m/d, with an average of 25.21 mg/sq. m/d, whereas N2O emission ranged between 0.41 and 0.80 mg/sq. m/d (average of 0.62 mg/sq. m/d). The emission of CH4 and N2O correlated positively with the number of pneumatophores. In addition to the flux measurements, different parts of the roots of Avicennia marina were quantified for CH4 concentration. Invariably in all the seasons, measured CH4 concentrations were high in the cable roots, with gradual decrease through the pneumatophores below water level and the above water level. This clearly indicates the transport of CH4 through the roots. We were able to establish that CH4 was released passively through the mangrove pneumatophores and is also a source to the atmosphere. We present some additional information on transport mechanisms of CH4 through the pneumatophores and bubble release from the mangrove ecosystems. [ABSTRACT FROM AUTHOR]

We report seasonal variation in CH4 and N2O emission rate from solid storage of bovine manure in Delhi as well as emission factors and emission inventory from manure management systems in India. Emission flux observed in the year 2002–2003 was 4. 29±1, 4. 84±2. 44 and 12. 92±4. 25mgCH4 kg−1 dungday−1, as well as 31. 29±4. 93, 72. 11±16. 22 and 6. 39±1. 76μgN2Okg−1 dungday−1 in winter, summer and rainy seasons, respectively. CH4 emission factors varied from 0. 8 to 3. 3kghd−1 year−1 for bovines and were lower than IPCC-1996 default values. N2O emission factors varied from 3 to 11. 7mghd−1 year−1 from solid storage of manure. Inventory estimates were found to about 698±27GgCH4 from all manure management systems and 2. 3±0. 46tons of N2O from solid storage of manure for the year 2000. [Copyright &y& Elsevier]

Greenhouse gas (GHG) emissions from the livestock sector are confined to enteric fermentation and manure management. The present inventory is focused on estimation of GHGs using country-specific emission factors for ruminants based on Indian Feeding Standards as a measure of gross energy intake. The thrust is on uncertainty reduction by adopting country-specific animal performance data leading to the development of more refined emission factors. The estimated GHG emission is 9.0 Tg methane and 1 Gg nitrous oxide for the year 1997, and in terms of CO2 equivalent it is around 190 Tg. Methane emission is the dominant one, while nitrous oxide is negligible. Enteric fermentation is the major source of methane, accounting for 90% of total methane compared to 10% from manure management. Ruminants, especially bovines are the largest source (91%). The estimate also highlights hotspots, emission density, methane emissions from dairy and non-dairy bovines, milk yield vs methane, which are useful in formulating mitigation strategies. The abatement option in the Indian context is also highlighted. [ABSTRACT FROM AUTHOR]