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Abstract: The dynamics of reformation and replacement of gas hydrates were studied under nonequilibrium conditions. It was found that the reformation of gas hydrates is largely affected by the state of the gas‐water system and the restarting temperature. This suggests that the effects are caused by changes in the structure of the aqueous solution at a molecular level. Pure samples of CH4 gas hydrate were synthesized from ice crystals and the dissociated solution using the reformation method. Replacement of CO2 gas hydrate is achieved within a short duration in the solid‐phase sample of CH4 gas hydrate, if the pressure and temperature is precisely controlled in a pressure vessel.

It is increasingly acknowledged that climate change is influencing terrestrial ecosystems by increased drought and rainfall intensities. Soil microbes are key drivers of many processes in terrestrial systems and rely on water in soil pores to fulfill their life cycles and functions. However, little is known on how drought and rainfall fluctuations, which affect the composition and structure of microbial communities, persist once original moisture conditions have been restored. Here, we study how simulated short-term drying and re-wetting events shape the community composition of soil fungi and prokaryotes. In a mesocosm experiment, soil was exposed to an extreme drought, then re-wetted to optimal moisture (50% WHC, water holding capacity) or to saturation level (100% WHC). Composition, community structure and diversity of microbes were measured by sequencing ITS and 16S rRNA gene amplicons 3 weeks after original moisture content had been restored. Drying and extreme re-wetting decreased richness of microbial communities, but not evenness. Abundance changes were observed in only 8% of prokaryote OTUs, and 25% of fungal OTUs, whereas all other OTUs did not differ between drying and re-wetting treatments. Two specific legacy response groups (LRGs) were observed for both prokaryotes and fungi. OTUs belonging to the first LRG decreased in relative abundance in soil with a history of drought, whereas OTUs that increased in soil with a history of drought formed a second LRG. These microbial responses were spread among different phyla. Drought appeared to be more important for the microbial community composition than the following extreme re-wetting. 16S profiles were correlated with both inorganic N concentration and basal respiration and ITS profiles correlated with fungal biomass. We conclude that a drying and/or an extreme re-wetting history can persist in soil microbial communities via specific response groups composed of members with broad phylogenetic origins, with possible functional consequences on soil processes and plant species. As a large fraction of OTUs responding to drying and re-wetting belonged to the rare biosphere, our results suggest that low abundant microbial species are potentially important for ecosystem responses to extreme weather events.

Abstract Integration of solar photovoltaic (PV) and battery storage systems is an upward trend for residential sector to achieve major targets like minimizing the electricity bill, grid dependency, emission and so forth. In recent years, there has been a rapid deployment of PV and battery installation in residential sector. In this regard, optimal planning of PV-battery systems is a critical issue for the designers, consumers, and network operators due to high number of parameters that can affect the optimization problem. This paper aims to present a comprehensive and critical review on the effective parameters in optimal planning process of solar PV and battery storage system for grid-connected residential sector. The key parameters in process of optimal planning for PV-battery system are recognized and explained. These parameters are economic and technical data, objective functions, energy management systems, design constraints, optimization algorithms, and electricity pricing programs. A timely review on the state-of-the-art studies in PV-battery optimal planning is presented. The challenges, trends and latest developments in the topic are discussed. At the end, scopes for future studies are developed. It is found that new guidelines should be provided for the customers based on various electricity rates and demand response programs. Also, several design considerations like grid dependency and resiliency need further investigation in the optimal planning of PV-battery systems.

Abstract The 2013/2017 Nankai Trough (Japan) and 2017 Shenhu Area (China) offshore methane hydrate production tests showed the world the possibility and feasibility of the oceanic methane hydrate production by depressurization. However, the relatively low gas production rate still remained as one of the critical bottlenecks for the economical utilization. This study chose the Nankai Trough as a target area, and aimed at the gas recovery enhancement from the methane hydrate reservoir using vertical wells. A traditional single-vertical-well system and a new dual-vertical-well system were proposed, and special production strategies of the aggressive depressurization and permeability improvement were applied to these two systems for the effectiveness verification. Based on the 15-year simulation results, it was found that the middle low-permeability silt-dominated layers in the reservoir held the key to the gas recovery enhancement, and for the single-vertical-well system, the permeability improvement in this sublayer seemed more reliable and feasible than the aggressive depressurization. On the other hand, the dual-vertical-well system significantly exceeded the single-vertical-well system due to the synergistic effect of the two wellbores, and could raise the average gas production rate (9.5 × 103 m3/day) by one order of magnitude (to 7.9 × 104 m3/day). Moreover, if this new system was combined with the aggressive depressurization, the average gas production rate could be further raised by one order of magnitude (to 3.4 × 105 m3/day).

This paper investigates key innovative paradigms that seek enhanced consensus building on the sustainable mining agenda of the mineral resource development industry and realities on the ground. It reviews the 55 most relevant academic articles from 2000 to 2019, retrieved from the Web of Science, PubMed and International Conference on Sustainable Development Indicators in the Metals Industry databases. A systematic scoping review method was used to sieve the multitudes of entries obtained from the databases to generate appropriate publications that match the search terms used. Our survey finds a dearth of literature on the subject. Only one article directly confers the need for consensus building on sustainable mining. The existing literature does not suggest the modalities that would enhance indigenous groups’ understanding and appreciation of sustainable mining. This creates a gap between stakeholders with regard to what flags sustainable mining. This study also finds a lack of efforts to incorporate sustainable mining concepts into academic courses focusing on either mining or sustainable development. Thus, this paper suggests that the existing delusions on sustainable mining can be addressed if the science of assessing and communicating the principles of sustainable development in mining is suitably developed and applied in higher educational curricula, environmental literacy feats, community-initiated research and outreach activities. Incorporating indigenous knowledge can address the existing gaps between stakeholder groups and in science.

Aquaponics systems and technologies are growing primary industries in many countries, with high environmental and socio-economic advantages. Aquaponics is a closed-loop system that produces aquatic animals and plants in a new way using recirculated water and nutrients. With a growing world population expected to reach 9.7 billion by 2050, food production sustainability is a primary issue in today’s world agenda, and aquaponics and aquaculture systems can be potential contributors to the challenge. Observing the climate changes and global warming’s impact on the ecosystem, decreasing aqua animal stocks, and responding to increasing demand are turning points in the sustainability era. In the past 15 years, fish production has doubled, thus denoting that aquaponics transforms into commercial scales with a revolutionized production, high efficiency, and fewer resources’ utilization, thus requiring proper operation and management standards and practices. Therefore, this study aims to shape a new framework for sustainable aquaponics modeling and utilization as the all-in-one solution platform covering technical, managerial, socio-economic, institutional, and environmental measures within the suitability requirements. The proposed model in this study offers a systematic approach to the design and implementation of sustainability-efficient aquaponics and aquaculture systems. Through an exhaustive coverage of the topic, this research effort can be counted as a practical reference for researchers, scholars, experts, practitioners, and students in the context of aquaponics and aquaculture studies.