It is essential to abstract the key information from accounting results of greenhouse gas (GHG) emissions because it can provide a highly generalized and clear picture of GHG emissions, which is especially helpful for the public and policy makers. To clearly display the composition of GHG emissions, the concept of spectrum analysis is introduced and defined in this paper. Next, a multilayer analysis framework for national GHG emissions was proposed, which is represented by a pyramid of three layers: total emissions (first layer), emissions decomposed by gas type or sector (second layer), and emissions decomposed by both gas type and sector (third layer). Based on the analysis results from the first to third layers, the main compositional information of national GHG emissions was gradually summarized and analyzed until a spectrum of GHG emissions was acquired. The spectrum of GHG emissions displays the compositional structure of national GHG emissions in the different layers, which is helpful in identifying priorities for emissions reduction. A case study of Germany’s GHG emissions during 1990–2012 was conducted, which indicated that CO₂ and the energy sector were the biggest contributors to the total GHG emissions. Some suggestions for reducing GHG emissions are offered based on the obtained results. And the potential development of spectrum analysis for GHG emissions is also expected from aspects of both research and technology.

Microalgae grown heterotrophically are reported to grow well and yield more biomass and metabolites when compared to photoautotrophic cultivation. In the present study, the growth of Scenedesmus obliquus in solution containing glucose, urea, and diammonium phosphate as carbon (0.2–1.0 %), nitrogen (0.07–0.21 %) and phosphorus (0.04–0.12 %) sources was evaluated. While complete utilization of carbon and nitrogen at all concentration was observed on the third day, complete phosphate uptake by the microalga was observed only at 0.04 and 0.08 % concentrations. The microalga grown with C–N–P ratio of 0.2:0.14:0.08 % showed maximum biomass yield (1.23 g L⁻¹) in 5 days. Furthermore, the microalga was found to adapt itself to the heterotrophic mode of growth when cultivated in the sugar mill effluent with a sugar concentration of 1.8 g L⁻¹. Despite the complex characteristics of the substrate, S. obliquus exhibited maximum biomass yield of 1.28 g L⁻¹ with 55 and 31 % total protein and carbohydrate, respectively, in 12 days. Significant reduction in most of the physico-chemical parameters demonstrates the bioremediation potential of S. obliquus.

The dry tropical forests are among the most vulnerable ecosystems of the world and, however, are relatively understudied. These forests provide various ecosystem services, and are progressively being converted into patches of dry scrubs, savanna and marginal cropland systems, due to various anthropogenic perturbations. Soils of these regions are relatively nutrient poor with a patchy nutrient and water distribution pattern. Therefore, the variability in these natural resources imposed by the present climate change scenario may affect the forest plant community of dry tropics via its impact on seedling growth and recruitment. Seedlings are considered as the most sensitive stage of plant lifecycle, and therefore, understanding of seedling regeneration may help in restoration of forest ecosystems. Seedling growth is majorly regulated by various naturally occurring resources (such as light, water, nutrient, etc.) and disturbances (such as defoliation, grass competition, fire, etc.). Therefore, efforts on the regeneration of these forest systems are highly necessitated. In the present study, we critically reviewed the studies on seedling survival and growth under different resource and disturbance regimes with a special focus to dry tropical environment. We found that water, light, nutrients, herbivory, and grass competition majorly regulates recruitments, growth, and establishment of the tree seedling in dry tropical environment. Most of the studies are limited to observe the effect of one or two factors over the seedling survival and growth. However, the resources and disturbances may have an interactive effect over seedling growth. Therefore, studies encompassing the interactions of various growth factors (resources and disturbances) under different climatic conditions are urgently needed for the successful regeneration of tree seedlings and for the restoration of plant community. Moreover, it will improve our ability to manage the tropical vegetation under changing climatic scenario.

The manuscript highlights the tragedy of India’s extinct or near-extinct rivers and rivulets (i.e. very small rivers or streams) passing through some of the major Indian cities. These rivers were once considered healthy and sound systems supporting the population of a city by sustaining important sectors such as agriculture, pisciculture, transportation, industries, recreation among several others. Our motive is to attract attention of the scientific community, policymakers, government and non-governmental organizations and native dwellers towards this grave concern, where once sound ecosystems are today being damaged beyond the opportunity of rejuvenation. We have considered the instances of six Indian rivers and rivulets: the Bharalu and Bahini (Guwahati), Varuna and Assi (Varanasi) and Mula and Mutha (Pune). Today, most of these rivers are reduced to mere ‘nallahs’ or ‘sewers’ due to rapid, unplanned and haphazard developmental activities and urbanization processes ubiquitous in major Indian cities. For instance, River Assi in Varanasi is, today, almost no more. Encroachment is a common problem on all these river banks which results in extraordinary reduction in the width of the rivers and rivulets. As a consequence, the water flows to the banks of the rivers in no time even during a short rainfall episode. The deteriorating river systems in India pose major challenges to the sustenance of cities situated along them. Most of the pollution prevention initiatives by the central or the state governments are directed towards the major rivers such as the Ganga, practically ignoring the equally vital rivulets. Although local governments of most of these cities have undertaken initiatives to address the associated problems, the outcome of the same is highly dubious.

The management of soil organic carbon (SOC) has now been identified as the most imperative dimension for managing the global climate change as well as soil fertility. In this respect, various agro-ecological approaches such as organic and integrated nutrient management system have been proposed worldwide, though accepted with limited enthusiasm. The understanding of the different soil C pools and processes are of vital importance before the implementation of these agro-ecological management practices, as it determines the success of SOC management. In the present study, we tried to encompass various SOC pools and processes governing the SOC dynamics in the agro-ecosystems. In this paper, dry tropical ecosystems having a unique ecological behaviour (such as strong nutrient conservation mechanisms and potential C sink nature) have been discussed especially due to its potential role in global climate change and mitigation, and linked soil fertility. It is proposed that a multi-factorial experimentation involving quantitative and qualitative change in soil available N, microbial and aggregate attributes, which has been recently found to be of crucial significance, is required for the proper mechanistic understanding of SOC dynamics. It may also help in the identification of some integrative functional indicators, which can be used to achieve a balanced SOC dynamics via suitable agro-management.

There is continuous increase in quantum and variety of waste being generated by anthropogenic activities. Burgeoning amount of waste being generated has potential to harm the environment and human health. Aggravating the problem, ever-increasing energy demand is putting strain on the non-renewable sources of energy and there is huge gap between the demand and supply of energy. This has led the scientific communities to adopt innovative methods to reduce, reuse and recycle them. Therefore, there is an urgent need to minimize the quantity of waste and meet the current demand profile of energy is required; technologies to recover energy from waste can play a vital role in substantial energy recovery and reduction in waste for final disposal; in addition to meet the rising energy requirement. Generating power from waste has greatly reduced the environmental impact and dependency on fossil fuels for electricity generation. Economically also it is an optimal solution for recovery of heat and power from waste. This paper gives an overview of energy potential stored in waste, major available waste-to-energy technologies and also strategic action plan for implementation of these technologies.