Biofuel Production from Waste Cooking Oils and its Physicochemical Properties in Comparison to Petrodiesel

Haphazard mining and consumption of fossil fuels have reduced petroleum reserves causing fossil fuel depletion and environmental degradation; thus, reflecting the need for the cheaper, renewable and eco-friendly alternative source of petroleum to meet the fuel demand. A million liters of edible oil used for cooking foods and date expired oils from oil manufacturers are discarded into sewage. This study primarily intends to study the feasibility of biodiesel production using such waste oils. In this work, biodiesel was prepared from waste cooking oils by a process called transesterification with NaOH as a catalyst. Our results showed that methyl ester (biodiesel) (92.67±0.90%), soap materials (1.33±0.224%), and glycerol (6±0.68%) were obtained after the transesterification of waste cooking oil. The physicochemical properties of biodiesel such as density, viscosity, volatility, surface tension, and flashpoint were analyzed, which were found to be 0.862±0.006 g/cm3, 2.23±0.021 cP, 0.327×10-3±4.5×10-6 g/s, 32.03±0.138 dyne/cm, 169.67±0.810°C, respectively. These properties were compared with that of commercial diesel as well as with the values specified by the American Society for Testing and Materials (ASTM) D6751. The density and the surface tension of the biodiesel were found similar to that of petrodiesel but its volatility was 3 times lower. Fourier-transform infrared spectroscopy (FTIR) spectra of the biodiesel showed methyl ester functional group at 1436 cm-1. Based on the cost of the materials used for production, the cost of biodiesel was estimated to be about 81 Nepalese rupees (0.67 USD) per liter. The properties of biodiesel also met the standard values of ASTM D6751. These findings indicate that waste oil is one of the feasible biodiesel sources and it can be used as a suitable alternative to petrodiesel

Characterizing the Response of Vegetation Cover to Water Limitation in Africa Using Geostationary Satellites

Publisher Copyright: © 2022 The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals LLC on behalf of American Geophysical Union.Hydrological interactions between vegetation, soil, and topography are complex, and heterogeneous in semi-arid landscapes. This along with data scarcity poses challenges for large-scale modeling of vegetation-water interactions. Here, we exploit metrics derived from daily Meteosat data over Africa at ca. 5 km spatial resolution for ecohydrological analysis. Their spatial patterns are based on Fractional Vegetation Cover (FVC) time series and emphasize limiting conditions of the seasonal wet to dry transition: the minimum and maximum FVC of temporal record, the FVC decay rate and the FVC integral over the decay period. We investigate the relevance of these metrics for large scale ecohydrological studies by assessing their co-variation with soil moisture, and with topographic, soil, and vegetation factors. Consistent with our initial hypothesis, FVC minimum and maximum increase with soil moisture, while the FVC integral and decay rate peak at intermediate soil moisture. We find evidence for the relevance of topographic moisture variations in arid regions, which, counter-intuitively, is detectable in the maximum but not in the minimum FVC. We find no clear evidence for wide-spread occurrence of the “inverse texture effect” on FVC. The FVC integral over the decay period correlates with independent data sets of plant water storage capacity or rooting depth while correlations increase with aridity. In arid regions, the FVC decay rate decreases with canopy height and tree cover fraction as expected for ecosystems with a more conservative water-use strategy. Thus, our observation-based products have large potential for better understanding complex vegetation-water interactions from regional to continental scales.publishersversionpublishe

Global apparent temperature sensitivity of terrestrial carbon turnover modulated by hydrometeorological factors

We are in debt to FLUXNET principal investigators and researchers for the fundamental measurements and synthesis datasets used to build the upscaled and in situ flux datasets used in this study. The work used eddy covariance data from La Thuile Synthesis Dataset, which were provided by the FLUXNET community. In particular, we thank A. Altaf, J. Beringer, P. Blanken, C. Brümmer, S. Burns, J. Cleverly, E. Cremonese, T. Grünwald, P. Kolari, W. Jans, M. Leonardo, T. Manise, M. Mund, A. Noormets, E. Pendall, C. Pio, S. Prober, L. Šigut, A. Varlagin and W. Woodgate, who provided us with site-level measurements of soil carbon and vegetation biomass, and B. Amiro, J. Ardö, S. Arndt, D. Baldocchi, L. Belelli, F. Bosveld, D. Bowling, N. Buchmann, A. Christen, M. Cuntz, A. Desai, B. Drake, I. Goded, A. Goldstein, C. Gough, S. Ivan, L. Hutley, I. Janssens, M. Karan, H. Kobayashi, M. Korkiakoski, B. Kruijt, S. Linder, B. Loubet, I. Mammarella, S. Minerbi, W. Munger, Z. Nagy, D. Papale, A. Richardson, B. Ruiz, E.P. Sanchez-Canete, FCE. Silva, E. Veenendaal, S. Wharton, G. Wohlfahrt, J. Wood, D. Yakir and D. Zona, who provided contacts and/or references for us to find site-level measurements of soil carbon and vegetation biomass. We are thankful to S. Bao and S. Besnard for helping with collected and processed site-level FLUXNET and vegetation biomass data. We thank M. Migliavacca and M. Schrumpf for providing reference and useful resources for data collection. N.F. acknowledges support from the International Max Planck Research School for Global Biogeochemical Cycles. Publisher Copyright: © 2022, The Author(s).The ecosystem carbon turnover time—an emergent ecosystem property that partly determines the feedback between the terrestrial carbon cycle and climate—is strongly controlled by temperature. However, it remains uncertain to what extent hydrometeorological conditions may influence the apparent temperature sensitivity of τ, defined as the factor by which the carbon turnover time increases with a 10 °C rise in temperature (Q10). Here, we investigate the responses of the ecosystem carbon turnover to temperature and hydrometeorological factors using an ensemble of observation-based global datasets and a global compilation of in situ measurements. We find that temperature and hydrometeorology are almost equally important in shaping the spatial pattern of ecosystem carbon turnover, explaining 60 and 40% of the global variability, respectively. Accounting for hydrometeorological effects puts a strong constraint on Q10 values with a substantial reduction in magnitude and uncertainties, leading Q10 to converge to 1.6 ± 0.1 globally. These findings suggest that hydrometeorological conditions modulate the apparent temperature sensitivity of terrestrial carbon turnover times, confounding the role of temperature in quantifying the response of the carbon cycle to climate change.publishersversionpublishe

Observation-based assessment of secondary water effects on seasonal vegetation decay across Africa

Funding Information: ÇK acknowledges funding from the International Max Planck Research School for Global Biogeochemical Cycles. SK acknowledges the support of the Erdsystemforschung: Afrikanische Grundwasserressourcen im Zuge des globalen Wandels (Earth System Research: Groundwater Resources in Africa under Global Change) project of the Max Planck Society. DM acknowledges funding from the European Research Council (ERC) under grant agreement 715254 (DRY-2-DRY) and the European Union Horizon 2020 Programme project 869550 (DOWN2EARTH). MR acknowledges funding by the European Research Council (ERC) Synergy Grant Understanding and modeling the Earth System with Machine Learning (USMILE) under the Horizon 2020 research and innovation program (Grant Agreement No. 855187). Publisher Copyright: Copyright © 2022 Küçük, Koirala, Carvalhais, Miralles, Reichstein and Jung.Local studies and modeling experiments suggest that shallow groundwater and lateral redistribution of soil moisture, together with soil properties, can be highly important secondary water sources for vegetation in water-limited ecosystems. However, there is a lack of observation-based studies of these terrain-associated secondary water effects on vegetation over large spatial domains. Here, we quantify the role of terrain properties on the spatial variations of dry season vegetation decay rate across Africa obtained from geostationary satellite acquisitions to assess the large-scale relevance of secondary water effects. We use machine learning based attribution to identify where and under which conditions terrain properties related to topography, water table depth, and soil hydraulic properties influence the rate of vegetation decay. Over the study domain, the machine learning model attributes about one-third of the spatial variations of vegetation decay rates to terrain properties, which is roughly equally split between direct terrain effects and interaction effects with climate and vegetation variables. The importance of secondary water effects increases with increasing topographic variability, shallower groundwater levels, and the propensity to capillary rise given by soil properties. In regions with favorable terrain properties, more than 60% of the variations in the decay rate of vegetation are attributed to terrain properties, highlighting the importance of secondary water effects on vegetation in Africa. Our findings provide an empirical assessment of the importance of local-scale secondary water effects on vegetation over Africa and help to improve hydrological and vegetation models for the challenge of bridging processes across spatial scales.publishersversionpublishe

Vertically divergent responses of SOC decomposition to soil moisture in a changing climate

The role of soil moisture for organic matter decomposition rates remains poorly understood and underrepresented in Earth System Models (ESMs). We apply the Dual Arrhenius Michaelis-Menten (DAMM) model to a selection of ESM soil temperature and moisture outputs to investigate their effects on decomposition rates, at different soil depths, for a historical period and a future climate period. Our key finding is that the inclusion of soil moisture controls has diverging effects on both the speed and direction of projected decomposition rates (up to ± 20%), compared to a temperature-only approach. In the top soil, the majority of these changes is driven by substrate availability. In deeper soil layers, oxygen availability plays a relatively stronger role. Owing to these different moisture controls along the soil depth, our study highlights the need for depth-resolved inclusion of soil moisture effects on decomposition rates within ESMs. This is particularly important for C-rich soils in regions which may be subject to strong future warming and vertically opposing moisture changes, such as the peat soils at northern high latitudes.Vertically divergent responses of SOC decomposition to soil moisture in a changing climatepublishedVersio

Global sensitivities of forest carbon changes to environmental conditions

40000125197/18/I‐NBThe responses of forest carbon dynamics to fluctuations in environmental conditions at a global scale remain elusive. Despite the understanding that favourable environmental conditions promote forest growth, these responses have been challenging to observe across different ecosystems and climate gradients. Based on a global annual time series of aboveground biomass (AGB) estimated from radar satellites between 1992 and 2018, we present forest carbon changes and provide insights on their sensitivities to environmental conditions across scales. Our findings indicate differences in forest carbon changes across AGB classes, with regions with carbon stocks of 50–125 MgC ha−1 depict the highest forest carbon gains and losses, while regions with 125–150 MgC ha−1 have the lowest forest carbon gains and losses in absolute terms. Net forest carbon change estimates show that the arc-of-deforestation and the Congo Basin were the main hotspots of forest carbon loss, while a substantial part of European forest gained carbon during the last three decades. Furthermore, we observe that changes in forest carbon stocks were systematically positively correlated with changes in forest cover fraction. At the same time, it was not necessarily the case with other environmental variables, such as air temperature and water availability at the bivariate level. We also used a model attribution method to demonstrate that atmospheric conditions were the dominant control of forest carbon changes (56% of the total study area) followed by water-related (29% of the total study area) and vegetation (15% of the total study area) conditions. Regionally, we find evidence that carbon gains from long-term forest growth covary with long-term carbon sinks inferred from atmospheric inversions. Our results describe the contributions from the atmosphere, water-related and vegetation conditions to forest carbon changes and provide new insights into the underlying mechanisms of the coupling between forest growth and the global carbon cycle.publishersversionpublishe

Apparent ecosystem carbon turnover time: Uncertainties and robust features

No. 4000113100/14/I-NBThe turnover time of terrestrial ecosystem carbon is an emergent ecosystem property that quantifies the strength of land surface on the global carbon cycle-climate feedback. However, observation- and modelingbased estimates of carbon turnover and its response to climate are still characterized by large uncertainties. In this study, by assessing the apparent whole ecosystem carbon turnover timesas the ratio between carbon stocks and fluxes, we provide an update of this ecosystem level diagnostic and its associated uncertainties in high spatial resolution (0.083) using multiple, state-of-the-art, observation-based datasets of soil organic carbon stock (Csoil), vegetation biomass (Cveg) and gross primary productivity (GPP). Using this new ensemble of data, we estimated the global median to be 43C7 -7 yr (medianCdifference to percentile 75 -difference to percentile 25) when the full soil is considered, in contrast to limiting it to 1m depth. Only considering the top 1m of soil carbon in circumpolar regions (assuming maximum active layer depth is up to 1 m) yields a global median of 37C3 -6 yr, which is longer than the previous estimates of 23C7 -4 yr (Carvalhais et al., 2014). We show that the difference is mostly attributed to changes in global Csoil estimates. Csoil accounts for approximately 84% of the total uncertainty in global estimates; GPP also contributes significantly (15 %), whereas Cveg contributes only marginally (less than 1 %) to the total uncertainty. The high uncertainty in Csoil is reflected in the large range across state-of-the-art data products, in which full-depth Csoil spans between 3362 and 4792 PgC. The uncertainty is especially high in circumpolar regions with an uncertainty of 50% and a low spatial correlation between the different datasets (0:2 < r < 0:5) when compared to other regions (0:6 < r < 0:8). These uncertainties cast a shadow on current global estimates of in circumpolar regions, for which further geographical representativeness and clarification on variations in Csoil with soil depth are needed. Different GPP estimates contribute significantly to the uncertainties of mainly in semiarid and arid regions, whereas Cveg causes the uncertainties of in the subtropics and tropics. In spite of the large uncertainties, our findings reveal that the latitudinal gradients of are consistent across different datasets and soil depths. The current results show a strong ensemble agreement on the negative correlation between and temperature along latitude that is stronger in temperate zones (30-60 N) than in the subtropical and tropical zones (30 S-30 N). Additionally, while the strength of the -precipitation correlation was dependent on the Csoil data source, the latitudinal gradients also agree among different ensemble members. Overall, and despite the large variation in , we identified robust features in the spatial patterns of that emerge beyond the differences stemming from the data-driven estimates of Csoil, Cveg and GPP. These robust patterns, and associated uncertainties, can be used to infer -climate relationships and for constraining contemporaneous behavior of Earth system models (ESMs), which could contribute to uncertainty reductions in future projections of the carbon cycle-climate feedback. The dataset of is openly available at https://doi.org/10.17871/bgitau.201911 (Fan et al., 2019).publishersversionpublishe

Potential surface active agent production using very low grade and cheap substrate by Bacillus subtilis as microbial cell factory

Bio-surfactants are surface-active molecules which are produced by the wide range of microbes including bacteria, fungi, moulds, and yeast. This study was conducted to identify bio-surfactants by Bacillus subtilis combined with use of cheap substrates and industrial wastes (Mustard cake, Whey and Soya cake) which are found locally in Nepal. Bacillus subtilis, one of the most potential bio-surfactants producer; was isolated from soil sample of hydrocarbon contaminated site. Isolates were grown in a Minimal Salt Media (MSM) with 10% (v/v) mustard oil cake, whey and soya cake separately. The presence and potential of surfactant was determined by the oil spreading technique, emulsification index (%E24) and surface tension measurement. It was revealed that the surface tensions of cell free extract were 54.41, 60.02 and 56.64 mN/m for from mustard cake, whey and soya cake respectively as compared to distilled water (72.09) at 25oC. The emulsification index values was found to be highest in engine oil from the bio-surfactant extracted from mustard cake, soya cake and whey respectively. Similarly, mustard oil showed the lowest value of emulsification index. The highest emulsification activity was shown in mustard oil i.e. 1.13 from the cell free extract from mustard oil and lowest in engine oil i.e., 0.07, by the extract from soya cake medium, when measured in spectrophotometer at 540 nm. In conclusion, strain of Bacillus subtilis was found to be the potential surface active agent producers on the mustard oil cake, which can be useful medium for various environmental, food, medicinal and industrial processes

A single-dose antibiotic prophylaxis to prevent surgical site infection in clean-contaminated surgery among diabetic patients

Introductions: Guidelines on antibiotics use in surgical patients recommends asingle dose prophylaxis for clean-contaminated cases and therapeutic coursefor contaminated and dirty cases. Compliance to this guideline is poor amongdiabetic patients. The aim of this study was to test the efficacy of single doseantibiotic prophylaxis on the occurrence of postoperative surgical site infection(SSI) in clean-contaminated surgery in diabetic patients.Methods: Retrospective cross-sectional study was carried out at KIST MedicalCollege and Teaching Hospital from September 2008 to August 2012 involving144 diabetic patients who underwent major clean-contaminated surgery. Fortyeight patients received one gram of ceftriaxone intravenously as prophylacticantibiotic within 30 minutes prior to incision (group 1) and 96 patients receivedthree doses of ceftriaxone (group 2). One dose was given within 30 minutesprior to incision and other two doses were given postoperatively. All patientswere followed up for 30 postoperative days on outpatient basis. The SSI rateswere compared in two groups. Pus from the infected wound was tested forculture and sensitivity.Results: The SSI rates in group 1 and group 2 were of 5/48 (10.42%) and of 9/96 (9.37%) respectively. There was no significant difference in SSI rates between group 1 and group 2 (p=0.322).Conclusions: Single dose of Ceftriaxone shows the similar effect as three dosesin clean-contaminated surgery in diabetic patients.Keywords: antibiotic prophylaxis, diabetic patients, surgical site infectio

Environment-sensitivity functions for gross primary productivity in light use efficiency models

The sensitivity of photosynthesis to environmental changes is essential for understanding carbon cycle responses to global climate change and for the development of modeling approaches that explains its spatial and temporal variability. We collected a large variety of published sensitivity functions of gross primary productivity (GPP) to different forcing variables to assess the response of GPP to environmental factors. These include the responses of GPP to temperature; vapor pressure deficit, some of which include the response to atmospheric CO2 concentrations; soil water availability (W); light intensity; and cloudiness. These functions were combined in a full factorial light use efficiency (LUE) model structure, leading to a collection of 5600 distinct LUE models. Each model was optimized against daily GPP and evapotranspiration fluxes from 196 FLUXNET sites and ranked across sites based on a bootstrap approach. The GPP sensitivity to each environmental factor, including CO2 fertilization, was shown to be significant, and that none of the previously published model structures performed as well as the best model selected. From daily and weekly to monthly scales, the best model's median Nash-Sutcliffe model efficiency across sites was 0.73, 0.79 and 0.82, respectively, but poorer at annual scales (0.23), emphasizing the common limitation of current models in describing the interannual variability of GPP. Although the best global model did not match the local best model at each site, the selection was robust across ecosystem types. The contribution of light saturation and cloudiness to GPP was observed across all biomes (from 23% to 43%). Temperature and W dominates GPP and LUE but responses of GPP to temperature and W are lagged in cold and arid ecosystems, respectively. The findings of this study provide a foundation towards more robust LUE-based estimates of global GPP and may provide a benchmark for other empirical GPP products.publishersversionpublishe