Co-benefits of a carbon tax in Nepal

This paper analyzes the co-benefits of introducing a time variant carbon (C) tax scheme in Nepal, a hydropower resourceful country, by using a bottom up integrated energy system model based on the MARKet ALlocation (MARKAL) framework with time horizon of 2005–2050. It discusses the effects of C tax on energy mix, environmental emissions, energy supply security, energy efficiency, energy system cost, and employment benefit. The study shows that the C tax (that gradually increases from US13/tCO < sub > 2 < /sub > e in 2015 to US 13/tCO₂e in 2015 to US 200/tCO₂e by 2050) results in a reduction of the cumulative emission of greenhouse gases by 83.9 million tons CO₂e (12%) as compared to that in the base case. With the introduction of the C tax, there would be a need for additional hydropower capacity of 945 MW by 2050 as compared to the capacity in the base case. The emission of local pollutants consisting of sulphur dioxide (SO₂), nitrogen oxides (NO_x) and non-methane volatile organic compound (NMVOC) in 2050 would be reduced by 12%, 7% and 1% respectively under the C tax scenario. Total amount of imported energy would decrease by 13%, which corresponds to a reduction in discounted net fuel import cost by 5% during the study period. Furthermore, the C tax would result in new employment generation of 151 thousand man-years associated with the additional hydropower capacity requirement.     

Characteristics of microbial community functional structure of a biological coking wastewater treatment system

Nitrogenous heterocyclic compounds are key pollutants in coking wastewater; however, the functional potential of microbial communities for biodegradation of such contaminants during biological treatment is still elusive. Herein, a high throughput functional gene array (GeoChip 5.0) in combination with Illumina HiSeq2500 sequencing was used to compare and characterize the microbial community functional structure in a long run (500 days) bench scale bioreactor treating coking wastewater, with a control system treating synthetic wastewater. Despite the inhibitory toxic pollutants, GeoChip 5.0 detected almost all key functional gene (average 61,940 genes) categories in the coking wastewater sludge. With higher abundance, aromatic ring cleavage dioxygenase genes including multi ring1,2diox; one ring2,3diox; catechol represented significant functional potential for degradation of aromatic pollutants which was further confirmed by Illumina HiSeq2500 analysis results. Response ratio analysis revealed that three nitrogenous compound degrading genes- nbzA (nitro-aromatics), tdnB (aniline), and scnABC (thiocyanate) were unique for coking wastewater treatment, which might be strong cause to increase ammonia level during the aerobic process. Additionally, HiSeq2500 elucidated carbozole and isoquinoline degradation genes in the system. These findings expanded our understanding on functional potential of microbial communities to remove organic nitrogenous pollutants; hence it will be useful in optimization strategies for biological treatment of coking wastewater.     

Bio-mediated silver nanoparticle synthesis: mechanism and microbial inactivation

Even though plenty of literature is available on the biosynthesis of metal nanoparticles, there are serious lacunae on the mechanisms of their formation. In the present study, the mechanism of formation of mono-crystalline silver nanoparticles using a fruit extract of the ornamental tree Thevetia peruviana is emphasized, i.e. how the pH of the reaction mixture affected reaction kinetics and size of the nanoparticles. The facilitation of formation of Ag₂O at higher pH resulted in a faster rate of particle formation. The diameter of the bare particles at neutral pH determined by field emission scanning electron microscopy and the hydrodynamic diameter determined by dynamic light scattering were 53 and 104 nm, respectively. The silver nanoparticles exhibited good inactivation of Escherichia coli due to participation of free radicals as evidenced by electron spin resonance spectroscopy.     

Soil adsorption studies of a rice herbicide,cyhalofop-butyl,in two texturally different soils of India

The ability of herbicides to be adsorbed by the soil and sediment and their tendency to be desorbed are some of the most important factors affecting soil and water contamination. Therefore, a sorption study was conducted to evaluate the adsorption of cyhalofop-butyl, butyl (2R)-2-[4-(4-cyano-2-fluorophenoxy) phenoxy] propanoate, in the sandy clay loam and clayey soils using a batch equilibrium method. The adsorption of cyhalofop-butyl was found positively related with the clay and organic carbon content. Freundlich constants (K _f) of cyhalofop-butyl in the clayey and sandy clay loam were found to be 13.39 and 2.21, respectively. Sorption coefficients (K _oc) and distribution coefficients (K _d) were found to be 265.38 and 2,092.79, and 1.38 and 11.48, for sandy clay loam and clayey soils, respectively. The adsorption isotherm suggested a relatively higher affinity of cyhalofop-butyl to the adsorption sites at low equilibrium concentrations. The low value of the soil organic carbon partition coefficient (K _oc) of cyhalofop-butyl in the sandy loam soil suggested its weaker adsorption in soil and thus increased its risk of mobility into water sources; hence, it should be used judiciously to prevent groundwater contamination     

Monitoring changes in soil organic carbon pools, nitrogen, phosphorus, and sulfur under different agricultural management practices in the tropics

Soil organic matter not only affects sustainability of agricultural ecosystems, but also extremely important in maintaining overall quality of environment as soil contains a significant part of global carbon stock. Hence, we attempted to assess the influence of different tillage and nutrient management practices on various stabilized and active soil organic carbon pools, and their contribution to the extractable nitrogen phosphorus and sulfur. Our study confined to the assessment of impact of agricultural management practices on the soil organic carbon pools and extractable nutrients under three important cropping systems, viz. soybean–wheat, maize–wheat, and rice–wheat. Results indicated that there was marginal improvement in Walkley and Black content in soil under integrated and organic nutrient management treatments in soybean–wheat, maize–wheat, and rice–wheat after completion of four cropping cycles. Improvement in stabilized pools of soil organic carbon (SOC) was not proportional to the applied amount of organic manures. While, labile pools of SOC were increased with the increase in amount of added manures. Apparently, green manure (Sesbania) was more effective in enhancing the lability of SOC as compared to farmyard manure and crop residues. The KMnO₄-oxidizable SOC proved to be more sensitive and consistent as an index of labile pool of SOC compared to microbial biomass carbon. Under different cropping sequences, labile fractions of soil organic carbon exerted consistent positive effect on the extractable nitrogen, phosphorus, and sulfur in soil.     

Effectiveness of the Local Adaptation Plan of Action to support climate change adaptation in Nepal

A key challenge in climate change adaptation in developing countries as a whole, and to handling global change in particular, is to link local adaptation needs on the one hand, with national adaptation initiatives on the other, so that vulnerable households and communities can directly benefit. This study assesses the impact of the Nepal government’s efforts to promote its Local Adaptation Plan of Action (LAPA) and its applicability to other least developed countries (LDCs). Based on data gathered from two field studies in Nepal, the research shows that the Nepal’s LAPA has succeeded in mobilizing local institutions and community groups in adaptation planning and recognizing their role in adaptation. However, the LAPA approach and implementation have been constrained by sociostructural and governance barriers that have failed to successfully integrate local adaptation needs in local planning and increase the adaptive capacity of vulnerable households. This paper describes the mechanisms of suitable governance strategies for climate change adaptation specific to Nepal and other LDCs. It also argues the need to adopt an adaptive comanagement approach, where the government and all stakeholders identify common local- and national-level mainstreaming strategy for knowledge management, resource mobilization, and institutional development, ultimately using adaptation as a tool to handle global change.     

A Time-Dependent System for Evaluating Groundwater Contamination Hazard Rating of Municipal Solid Waste Dumps

In developing countries, several old municipal solid waste dumps (unlined landfills) exist adjacent to large cities, releasing contaminants to the underlying aquifer, thus posing the hazard of groundwater contamination. These uncontrolled waste dumps need to be prioritized in terms of the groundwater contamination hazard posed by them, so that necessary control and remedial measures can be undertaken in a phased manner. This paper presents a time-dependent system for evaluating groundwater contamination hazard rating of municipal solid waste dumps. The system is based on source–pathway–receptor relationships and evaluates the relative value of hazard posed by a site over its entire leaching life, on a scale of 0–1,000. The system parameters have been selected based on literature and expert opinions. The Delphi technique is used to derive the relative importance weights of the system parameters. The proposed system is compared with six selected existing hazard rating systems. The comparison, made by way of score range analysis, shows that the proposed system exhibits a much wider range of hazard scores for various scenarios of site conditions, and hence the proposed system is more sensitive to varied site conditions. The application of different systems to six municipal solid waste dumps located in four cities of India shows that, whereas the existing systems individually produce clustered scores and return the same rank to more than one site, the proposed system produces significantly varying scores and return different ranks to different sites. This demonstrates that the proposed system improves decision making and makes a better basis for prioritization of municipal solid waste dumps for adopting control and remedial measures.     

Mapping the industries’ willingness to pay for unrestricted electricity supply

Environment, Development and Sustainability - The supply of electric power plays a crucial role in industrial production, and the current scarcity of electricity prevailing in the industries...     

Design of optimized PI controller for 7-level inverter: a new control strategy

Photovoltaic (PV) system produces electricity that differs from variations in environmental parameters such as temperature and solar radiation. The PV network will operate at maximum power point (MPP) and deal with an ever-increasing energy demand, that changes from both load and weather conditions.” Moreover, energy storage devices could be a potential solution for improving the efficiency and performance of renewable energy sources (RES). This paper intends to establish a control design by an optimization-assisted PI controller for a 7-level inverter. Accordingly, the gains of PI controller are adjusted dynamically by FireFly Integrated-Sea Lion Optimization algorithm (FFI-SLnO) that integrates the concepts of both Sea Lion Optimization (SLnO) and FireFly algorithm (FF). The gains should be tuned such that the error among the reference signal and fault signal should be low and hence better dynamic performance can be obtained by the presented optimized PI controller. Finally, the performance of the proposed method is compared over other traditional models with respect to certain measures and its superiority is proved.