Environmental Chemistry Letters - The rising amount of waste generated worldwide is inducing issues of pollution, waste management, and recycling, calling for new strategies to improve the waste... 相似文献
Traditional fertilizers are highly inefficient, with a major loss of nutrients and associated pollution. Alternatively, biochar loaded with phosphorous is a sustainable fertilizer that improves soil structure, stores carbon in soils, and provides plant nutrients in the long run, yet most biochars are not optimal because mechanisms ruling biochar properties are poorly known. This issue can be solved by recent developments in machine learning and computational chemistry. Here we review phosphorus-loaded biochar with emphasis on computational chemistry, machine learning, organic acids, drawbacks of classical fertilizers, biochar production, phosphorus loading, and mechanisms of phosphorous release. Modeling techniques allow for deciphering the influence of individual variables on biochar, employing various supervised learning models tailored to different biochar types. Computational chemistry provides knowledge on factors that control phosphorus binding, e.g., the type of phosphorus compound, soil constituents, mineral surfaces, binding motifs, water, solution pH, and redox potential. Phosphorus release from biochar is controlled by coexisting anions, pH, adsorbent dosage, initial phosphorus concentration, and temperature. Pyrolysis temperatures below 600 °C enhance functional group retention, while temperatures below 450 °C increase plant-available phosphorus. Lower pH values promote phosphorus release, while higher pH values hinder it. Physical modifications, such as increasing surface area and pore volume, can maximize the adsorption capacity of phosphorus-loaded biochar. Furthermore, the type of organic acid affects phosphorus release, with low molecular weight organic acids being advantageous for soil utilization. Lastly, biochar-based fertilizers release nutrients 2–4 times slower than conventional fertilizers.
Historically, paddy soils are the most valuable natural resources that produce about 90% of staple food in eastern coastal
China. Dispersed patterns of rapid rural settlement expansion, or “exurban”, are recognized as key threats to the region’s
food security through paddy soil loss. Analyzing the process of ex-urbanization and its impact has profound implications for
the sustainable development of rural China. Based on official statistics and data derived from satellite images, dynamics
of rural settlement expansion and paddy soil loss were outlined for Tiaoxi watershed during China’s market transition period
(1994–2003). Particularly, rural settlements became more aggregated and total area expanded by 183% at an average rate of
12.3% per year for the whole watershed. Existing cores, open areas away from urban centers and areas near major transportation
lines and river channels, observed the highest specialization in rural residential growth. Being closely associated with rural
settlement in spatial distribution, open large paddy soil patches acted as another kind of center for rural settlement expansion
within the landscape. Variations in rural settlement expansion were detected among different-tier counties, such as speed
of rural settlement expansion, speed of build-ups growth per capita. These variations were closely related to social-economic
development. The rapid rural settlement expansion led to a considerable loss of paddy soil, about 11% of the total amount
for the whole watershed. Linear regression identified a significant relationship between paddy soil loss and rural settlement
expansion. Given the social and ecological problems associated with paddy soil loss, we argue that innovative and effective
planning policies as well as management programs that target at paddy soil protection should be developed and implemented
in rural China. In particular, we suggest using watershed as an appropriate spatial unit for sustainable paddy soil management
in this investigation. 相似文献
Environmental Chemistry Letters - The construction industry is a major user of non-renewable energy and contributor to emission of greenhouse gases, thus requiring to achieve net-zero carbon... 相似文献
Environmental Chemistry Letters - New technologies, systems, societal organization and policies for energy saving are urgently needed in the context of accelerated climate change, the Ukraine... 相似文献
Burning fossil fuels account for over 75% of global greenhouse gas emissions and over 90% of carbon dioxide emissions, calling for alternative fuels such as hydrogen. Since the hydrogen demand could reach 120 million tons in 2024, efficient and large-scale production methods are required. Here we review electrocatalytic water splitting with a focus on reaction mechanisms, transition metal catalysts, and optimization strategies. We discuss mechanisms of water decomposition and hydrogen evolution. Transition metal catalysts include alloys, sulfides, carbides, nitrides, phosphides, selenides, oxides, hydroxides, and metal-organic frameworks. The reaction can be optimized by modifying the nanostructure or the electronic structure. We observe that transition metal-based electrocatalysts are excellent catalysts due to their abundant sources, low cost, and controllable electronic structures. Concerning optimization, fluorine anion doping at 1 mol/L potassium hydroxide yields an overpotential of 38 mV at a current density of 10 mA/cm2. The electrocatalytic efficiency can also be enhanced by adding metal atoms to the nickel sulfide framework.