Food–energy–water nexus optimization brings substantial reduction of urban resource consumption and greenhouse gas emissions

Urban sustainability is a key to achieving the UN sustainable development goals (SDGs). Secure and efficient provision of food, energy, and water (FEW) resources is a critical strategy for urban sustainability. While there has been extensive discussion on the positive effects of the FEW nexus on resource efficiency and climate impacts, measuring the extent to which such synergy can benefit urban sustainability remains challenging. Here, we have developed a systematic and integrated optimization framework to explore the potential of the FEW nexus in reducing urban resource demand and greenhouse gas (GHG) emissions. Demonstrated using the Metropolis Beijing, we have identified that the optimized FEW nexus can reduce resource consumption and GHG emissions by 21.0 and 29.1%, respectively. These reductions come with increased costs compared to the siloed FEW management, but it still achieved a 16.8% reduction in economic cost compared to the business-as-usual scenario. These findings underscore the significant potential of FEW nexus management in enhancing urban resource efficiency and addressing climate impacts, while also identifying strategies to address trade-offs and increase synergies

The role of Chinese herbal medicine in the treatment of diabetic nephropathy by regulating endoplasmic reticulum stress

Diabetic nephropathy (DN), a prevalent microvascular complication of diabetes mellitus, is the primary contributor to end-stage renal disease in developed countries. Existing clinical interventions for DN encompass lifestyle modifications, blood glucose regulation, blood pressure reduction, lipid management, and avoidance of nephrotoxic medications. Despite these measures, a significant number of patients progress to end-stage renal disease, underscoring the need for additional therapeutic strategies. The endoplasmic reticulum (ER) stress response, a cellular defense mechanism in eukaryotic cells, has been implicated in DN pathogenesis. Moderate ER stress can enhance cell survival, whereas severe or prolonged ER stress may trigger apoptosis. As such, the role of ER stress in DN presents a potential avenue for therapeutic modulation. Chinese herbal medicine, a staple in Chinese healthcare, has emerged as a promising intervention for DN. Existing research suggests that some herbal remedies may confer renoprotective benefits through the modulation of ER stress. This review explores the involvement of ER stress in the pathogenesis of DN and the advancements in Chinese herbal medicine for ER stress regulation, aiming to inspire new clinical strategies for the prevention and management of DN

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Environmental sustainability of small hydropower schemes in Tibet: An emergy-based comparative analysis

Exploring safe and sustainable hydropower, with regard to the size and scheme, is of particular importance to avoid unsettling the fragile ecology in Tibet. Through emergy analysis, this study aimed to assess and compare the environmental performance and sustainability of three different small hydropower (SHP) schemes that are currently in use, i.e., dam-toe, diversion and hybrid, in the Nagqu Prefecture of Tibet. The results indicate that the main difference among the three schemes is the high emergy cost associated with the sizeable dam and related sediment deposition. Correspondingly, the diversion scheme without the dam component is superior to the other two schemes with respect to environmental performance. Considering the necessity of SHP in sparsely populated Tibet, the diversion scheme is recommended more highly than the other two schemes for new SHP plants that are being planned for construction. Because of the much higher resource cost but smaller installed capacity, all three case plants in Tibet present worse performance than their counterparts in Guizhou Province. These results help to encourage China's policy makers to be conservative and proceed with caution regarding SHP development in the fragile Tibetan ecosystem, although SHP has played and will continue to play an essential role in rural electrification in this unique region

Ecological impacts of small hydropower in China: Insights from an emergy analysis of a case plant

The belief that small hydropower (SHP) systems are sources of clean energy with few or no ecological problems has been driving the rapid expansion of SHP plants in China and elsewhere. This paper presents an evaluation of the ecological impacts of SHP based on an emergy analysis of a plant located in Guizhou Province in southwest China. The results suggest that periodic downstream drying-up of the river is the largest contributor to the induced ecological impacts in terms of emergy cost. In 2010, the ecosystem service losses caused by downstream ecosystem degradation totaled 2.35E+18. seJ, which accounts for 38% of the total emergy utilized in the annual operation of this plant. If such losses could be avoided, i.e., if the SHP operated as designed, SHP projects would produce relatively modest impacts on the environment. When the reaches downstream of the SHP plant are not affected, the environmental loading ratio (ELR) is 2.20 and the emergy sustainability index (ESI) is 0.93; however, the ELR increases to 3.82 and ESI decreases to 0.38 when river drying-up occurs. These results indicate that China should rigorously investigate potential ecological problems of SHP development and proceed with caution rather than readily believing unjustified assumptions

Spatiotemporal Variation of NDVI in the Vegetation Growing Season in the Source Region of the Yellow River, China

Research on vegetation variation is an important aspect of global warming studies. The quantification of the relationship between vegetation change and climate change has become a central topic and challenge in current global change studies. The source region of the Yellow River (SRYR) is an appropriate area to study global change because of its unique natural conditions and vulnerable terrestrial ecosystem. Therefore, we chose the SRYR for a case study to determine the driving forces behind vegetation variation under global warming. Using the Normalized Difference Vegetation Index (NDVI) and climate data, we investigated the NDVI variation in the growing season in the region from 1998 to 2016 and its response to climate change based on trend analysis, the Mann–Kendall trend test and partial correlation analysis. Finally, an NDVI–climate mathematical model was built to predict the NDVI trends from 2020 to 2038. The results indicated the following: (1) over the past 19 years, the NDVI showed an increasing trend, with a growth rate of 0.00204/a. There was an upward trend in NDVI over 71.40% of the region. (2) Both the precipitation and temperature in the growing season showed upward trends over the last 19 years. NDVI was positively correlated with precipitation and temperature. The areas with significant relationships with precipitation covered 31.01% of the region, while those with significant relationships with temperature covered 56.40%. The sensitivity of the NDVI to temperature was higher than that to precipitation. Over half (56.58%) of the areas were found to exhibit negative impacts of human activities on the NDVI. (3) According to the simulation, the NDVI will increase slightly over the next 19 years, with a linear tendency of 0.00096/a. From the perspective of spatiotemporal changes, we combined the past and future variations in vegetation, which could adequately reflect the long-term vegetation trends. The results provide a theoretical basis and reference for the sustainable development of the natural environment and a response to vegetation change under the background of climate change in the study area

Small hydropower development in China : Growing challenges and transition strategy

With the great successes in improving rural electrification and reducing poverty, China's small hydropower (SHP) development is expected to provide a good example for other developing countries. However, recently, nearly all new SHP development plans have been halted, and many plants have been urged to shut down or even be removed. The SHP industry in China is now in a dilemma. This paper presents a review of the status of SHP development in China and explores the challenges troubling this industry. It was revealed that SHP resources in many provinces have been intensively exploited, with an exploration rate over 0.80, while untapped resources are primarily located in remote western provinces, such as ecologically fragile Tibet. This intensive and disordered SHP development has caused serious dewatering of rivers and affected local agricultural and household water access, which arouses fierce controversy. Moreover, the role of SHP has been gradually weakened by the extension of power grids and diversified electricity sources. Therefore, the transition and upgrade of the SHP industry has become critical to enhance its sustainable development and to provide a solid example for the world. A divergence management strategy for SHP should be adopted to achieve low-impact development, as opposed to blind large-scale development or rigidly discontinuing all projects. Future transition strategies are proposed in this paper that include delicate management of existing plants and construction of new plants with higher standards, as well as pathways for the development benefits to be shared by a wider range of local residents.</p

Resource Dynamism of the Rwandan Economy: An Emergy Approach

Africa is experiencing unprecedented economic growth that requires planners to understand the interactions between the social, economic, and ecological systems to ensure its sustainable development. The present paper uses the emergy method to analyse the Rwandan economy from 1975 to 2016. Emergy-based sustainability indicators were used to analyse and compare two distinct periods of economic growth: the pre- and post-Tutsi genocide periods. The results revealed that, by 2016, the total emergy use had increased by approximately 74% of the emergy recorded in 1975. The increase in total emergy use was associated with an increase in imports with contributions from 6.5 to 46.2% and the renewable resource contribution decrease from 93.5 to 53.8%. The emergy analysis, which covered 41 years, categorises Rwanda as a non-renewable resource-poor country. The total emergy use of the pre-genocide period was significantly lower than the post-genocide period. Based on the 2016 emergy self-support of 54% and the emergy sustainability index of 2.52, Rwanda has the highest import dependence compared to other developing countries listed in this paper and tends toward a developed country like Canada, Portugal, and so on. An imperative decision needs to be made in terms of the management of the economic system of Rwanda, as imports are becoming the highest impetus of the Rwandan economy but are also the top major cause of a long-run sustainability downfall. Thus, the present study recommends a scrutinised selection system of imports by increasing raw materials, particularly non-renewable resources, and by subsequently increasing the internal transformation to be exported. This recommendation is also applicable to other developing countries with similar non-renewable resource statuses

Emergy Perspectives on the Environmental Performance and Sustainability of Small-Scale Gold Production Systems in Ghana

Small-scale gold mining is an important component of the Ghanaian economy but it has also caused enormous damage to local ecosystems. In this paper, an emergy analysis was conducted in Ghana to assess the environmental performance and the relative sustainability of two artisanal and small-scale gold production systems: alluvial “dig and wash” and underground “ghetto” mines. Results show that both production systems have high environmental impacts, as indicated by an environmental loading ratio (ELR) of 4.31 and environmental sustainability index (ESI) of 0.33 for the alluvial system and 2.53 and 0.52 for the underground system, respectively. Concerning the international trade balance, the emergy exchange ratios of the two systems are both lower than one, at, 0.23 and 0.33 for the alluvial and underground systems, respectively, indicating a significant amount of resource loss to foreign regions. This study could assist in the regulation of the small-scale mining sector bearing in mind the unsustainable nature of their activities. In addition, supporting miners to consider land rehabilitation ethics is urgently needed

Small hydropower development in Tibet: Insights from a survey in Nagqu Prefecture

Due to its large hydraulic power potential, Tibet has been proposed as the main hydropower development base in China after 2020. This is likely to result in the construction of large and medium sized hydropower projects in this region. To date, small hydropower (SHP) has played an essential role in rural electrification in Tibet. Here we present a review of the status of SHP plants in Tibet and explore its potential based on a field survey conducted in the summer of 2014 in Nagqu Prefecture. The survey revealed that SHP in Nagqu has made it possible for approximately 80,000 local residents (16.3% of the total population) to have access to electricity. Our study shows that SHP suffers from problems such as low utilization of the installed power capacity, high scrap ratio and has severe impacts on the local ecosystem. Moreover, the role of SHP in Tibet's rural electrification is gradually changing with the arrival of the main power grid, which has also impacted existing SHP plants. In order to improve SHP overall sustainability, optimization of existing plants and construction of new plants with highers tandards are deemed necessary. This has to be done with due consideration to the fragile ecosystem in Tibet. Therefore, any expansion in the development of SHP in Tibet should have an appropriate strategy for sustainability and ecosystems conservation and protection