Insight into electrochemically boosted trace Co(II)-PMS catalytic process: Sustainable Co(IV)/Co(III)/Co(II) cycling and side reaction blocking.

A novel homogeneous electrocatalytic system was constructed by current-assisted trace Co(II) activating PMS (ECP) to remove reactive blue 19 (RB19). More than 93 % of RB19 was rapidly removed with only a trace dose, and the PMS was 98.35 % utilized during the reaction. By exploring the active species and analyzing the PMS consumption, it was found that current strongly accelerated the Co(III)/Co(II) redox cycle by providing electrons to Co(III), and inhibited the side reaction thus improving the PMS utilization. Electric energy per order was very low, only 0.26 kWh·m3. Radicals (SO4•-) and non-radicals (Co(III), Co(IV) and 1O2) participated in ECP system, in which SO4•- was dominant. By excluding the other three precursors (PMS, •OH and O2•-), the side reaction product SO5•- was identified as the source of 1O2 in ECP system. Combining chelating agent EDTA and chemical probe PMSO, Co(IV) was considered formed by single and double charge transfer. Five degradation pathways of RB19 were proposed using mass spectrometry and DFT calculation. The ecotoxicity and mutagenicity of RB19 and its transformation products were predicted using software simulation. These studies provided an interesting insights into the synergistic Co(II)-PMS systems and offered a new strategy for electrochemical processes.

Reading bots: The implication of deep learning on guided reading.

This study introduces the application of deep-learning technologies in automatically generating guidance for independent reading. The study explores and demonstrates how to incorporate the latest advances in deep-learning-based natural language processing technologies in the three reading stages, namely, the pre-reading stage, the while-reading stage, and the post-reading stage. As a result, the novel design and implementation of a prototype system based on deep learning technologies are presented. This system includes connections to prior knowledge with knowledge graphs and summary-based question generation, the breakdown of complex sentences with text simplification, and the auto-grading of readers' writing regarding their comprehension of the reading materials. Experiments on word sense disambiguation, named entity recognition and question generation with real-world materials in the prototype system show that the selected deep learning models on these tasks obtain favorable results, but there are still errors to be overcome before their direct usage in real-world applications. Based on the experiment results and the reported performance of the deep learning models on reading-related tasks, the study reveals the challenges and limitations of deep learning technologies, such as inadequate performance, domain transfer issues, and low explain ability, for future improvement.

Hydrated electron based photochemical processes for water treatment.

Hydrated electron (eaq-) based photochemical processes have emerged as a promising technology for contaminant removal in water due to the mild operating conditions. This review aims to provide a comprehensive and up-to-date summary on eaq- based photochemical processes for the decomposition of various oxidative contaminants. Specifically, the characteristics of different photo-reductive systems are first elaborated, including the environment required to generate sufficient eaq-, the advantages and disadvantages of each system, and the comparison of the degradation efficiency of contaminants induced by eaq-. In addition, the identification methods of eaq- (e.g., laser flash photolysis, scavenging studies, chemical probes and electron spin resonance techniques) are summarized, and the influences of operating conditions (e.g., solution pH, dissolved oxygen, source chemical concentration and UV type) on the performance of contaminants are also discussed. Considering the complexity of contaminated water, particular attention is paid to the influence of water matrix (e.g., coexisting anions, alkalinity and humic acid). Moreover, the degradation regularities of various contaminants (e.g., perfluorinated compounds, disinfection by-products and nitrate) by eaq- are summarized. We finally put forward several research prospects for the decomposition of contaminants by eaq- based photochemical processes to promote their practical application in water treatment.

Efficient Activation of Peroxymonosulfate by Biochar-Loaded Zero-Valent Copper for Enrofloxacin Degradation: Singlet Oxygen-Dominated Oxidation Process.

The removal of contaminants of emerging concern (CECs) has become a hot research topic in the field of environmental engineering in recent years. In this work, a simple pyrolysis method was designed to prepare a high-performance biochar-loaded zero-valent copper (CuC) material for the catalytic degradation of antibiotics ENR by PMS. The results showed that 10 mg/L of ENR was completely removed within 30 min at an initial pH of 3, CuC 0.3 g/L, and PMS 2 mmol/L. Further studies confirmed that the reactive oxygen species (ROS) involved in ENR degradation are ·OH, SO4-·, 1O2, and O2-. Among them, 1O2 played a major role in degradation, whereas O2-· played a key role in the indirect generation of 1O2. On the one hand, CuC adsorbed and activated PMS to generate ·OH, SO4-· and O2-·. O2-· was unstable and reacted rapidly with H2O and ·OH to generate large amounts of 1O2. On the other hand, both the self-decomposition of PMS and direct activation of PMS by C=O on biochar also generated 1O2. Five byproducts were generated during degradation and eventually mineralized to CO2, H2O, NO3-, and F-. This study provides a facile strategy and new insights into the biochar-loaded zero-valent transition-metal-catalyzed PMS degradation of CECs.

Electrically supported mediator Co(II)-activated peroxydisulfate synergistic process for organic contaminants elimination.

Among homogeneous catalysts, cobalt ions exhibit ultra-high persulfate activation performance. In this work, an electrically supported medium Co(II) activated peroxydisulfate synergistic process was established to eliminate organic contaminants in water. The synergistic catalytic effect was verified by comparing the oxidative degradation performance and reaction rate constant of different coupling systems. The decolorization ability of E-Co(II)-PDS on reactive black 5 (RB5) was explored, and the results showed that the removal rate of RB5 can reach 93.21% under the optimized conditions of current density of 5.71 mA/cm2, initial pH of 4, Co(II) concentration of 0.2 mM and PDS concentration of 5 mM. The effect of water matrix on the removal of RB5 was studied, and it was found that HCO3- and humic acid significantly inhibited the degradation of RB5, while Cl- and H2PO4- could effectively promote it at a certain concentration. Notably, the degradation of RB5 in E-Co(II)-PDS system achieved lower energy consumption, with an energy consumption per unit volume (EE/O) value of 0.4304 kWh·m-3. EPR test, quenching experiments and contribution rate analysis showed that the oxidation active species in E-Co(II)-PDS process were Co(III), sulfate radicals and hydroxyl radicals, and their oxidation contribution rates were 15.72%, 12.69% and 53.25%, respectively. Finally, the decomposition process of RB5 was proposed by the mass spectrometry results. The electric current promotes cobalt ion cycling and PDS activation through electron transfer, and induces Co(II) to promote the activation of PDS, which is the main mechanism of E-Co(II)-PDS system to achieve the robust degradation ability of RB5.

The gap between public perceptions and monitoring indicators of environmental quality in Beijing.

This paper explores the differences between public perceptions and existing monitoring indicators in environmental quality in Beijing. The results reveal, existing indicators do not accurately reflect public perceptions of the environment. Some environmental problems, such as fluffy catkins, are not reflected in the existing indicators, yet have a relatively large influence on public perception. The policymakers and public's variegated understanding of the environment, the lag period of public perceptions of environmental quality change, and lack of standards and monitoring for emerging problems are the three main reasons that resulted in a deviation of monitoring indicators from the public perceptions. Resultantly, to improve the level of environmental governance, it is necessary to take relevant measures that reduce the difference between public perceptions and monitoring indicators. Residents should be surveyed regularly to obtain their public perceptions, and the selection of indicators should not be limited to environmental pollution. In particular, some indicators based on public perception should be developed to complement the existing environmental monitoring protocol. In addition, due to the emerging environmental problems, quality standards and monitoring systems should be updated regularly.

Assessing progress towards sustainable development over space and time.

To address global challenges1-4, 193 countries have committed to the 17 United Nations Sustainable Development Goals (SDGs)5. Quantifying progress towards achieving the SDGs is essential to track global efforts towards sustainable development and guide policy development and implementation. However, systematic methods for assessing spatio-temporal progress towards achieving the SDGs are lacking. Here we develop and test systematic methods to quantify progress towards the 17 SDGs at national and subnational levels in China. Our analyses indicate that China's SDG Index score (an aggregate score representing the overall performance towards achieving all 17 SDGs) increased at the national level from 2000 to 2015. Every province also increased its SDG Index score over this period. There were large spatio-temporal variations across regions. For example, eastern China had a higher SDG Index score than western China in the 2000s, and southern China had a higher SDG Index score than northern China in 2015. At the national level, the scores of 13 of the 17 SDGs improved over time, but the scores of four SDGs declined. This study suggests the need to track the spatio-temporal dynamics of progress towards SDGs at the global level and in other nations.

Importing food damages domestic environment: Evidence from global soybean trade.

Protecting the environment and enhancing food security are among the world's Sustainable Development Goals and greatest challenges. International food trade is an important mechanism to enhance food security worldwide. Nonetheless, it is widely concluded that in international food trade importing countries gain environmental benefits, while exporting countries suffer environmental problems by using land and other resources to produce food for exports. Our study shows that international food trade can also lead to environmental pollution in importing countries. At the global level, our metaanalysis indicates that there was increased nitrogen (N) pollution after much farmland for domestically cultivated N-fixing soybeans in importing countries was converted to grow high N-demanding crops (wheat, corn, rice, and vegetables). The findings were further verified by an intensive study at the regional level in China, the largest soybean-importing country, where the conversion of soybean lands to corn fields and rice paddies has also led to N pollution. Our study provides a sharp contrast to the conventional wisdom that only exports contribute substantially to environmental woes. Our results suggest the need to evaluate environmental consequences of international trade of all other major goods and products in all importing countries, which have significant implications for fundamental rethinking in global policy-making and debates on environmental responsibilities among consumers, producers, and traders across the world.

[Ecological Footprint Evolution Characteristics and Its Influencing Factors in China from 2000 to 2010].

According to global average land productivities in 2000, this study calculated ecological footprint (EF) in China from 2000 to 2010, and analyzed its dynamic characteristics and socio-economic driving forces. The results showed that the total EF in China increased from 1.769 to 3.259 billion global hectares (gha) from 2000 to 2010, and its annual growth rate was 6.30%. Carbon Footprint was the fastest growth type of EF. It increased from 0.742 to 1.805 billion gha, and its annual growth rate was 9.29%. The net increase of cropland Footprint was also large in comparison to other types of Footprint. It increased from 0.678 to 0.891 billion gha. Per capita EF in China increased from 1.40 to 2.43 gha in this period. Although it was still below the world average level, it was far beyond per capita ecological carrying capacity in China, which led to serious ecological deficit and severe ecological crisis in China. The fast growth of per capita EF was the main driving force for the growth of total EF in China during the study period. Further, the growth of per capita EF was positively influenced by the growth of per capita consumption of products and severs, which was driven by economic growth and urbanization. Meanwhile, a large amount of exports of resource-intensive products in international trade was also an important driving force for EF growth. According to the evolution route of per capita EF in developed countries, along with China moving from middle-income to high-income country, per capita EF will maintain rapid growth, and ecological deficit in China will further exacerbate.

Division scheme for environmental management regionalization in China.

Based on regional heterogeneity of environmental characteristics and factors influencing those characteristics, environmental units may be classified into homogeneous zones. Then, essential strategies and mitigation measures in each zone may be developed and environmental quality may be holistically improved using a system of environmental management regionalization (EMRZ). Here, an EMRZ scheme for China was devised by outlining regional management using integrated qualitative and quantitative methods. First, the land was subdivided into four environmental management domains using China's three physical geographic domains. Second, using a regionalization indicator system, the environmental characteristics of neighboring provinces in four domains was quantified using the one-dimensional Euclidean distance method; regions with high similarity were merged into one environmental management region (EMR) and the preliminary draft of EMRs was obtained. Based on the preliminary scheme, eight EMRs using prefecture-level administrative regions were obtained through boundary adjustment based on important natural geographical boundaries and existing regional plans. These include the Northeastern China Region, the North China Plain Region, the Loess Plateau Region, Southeast Coast Region, the Middle Reaches of the Yangtze River, the Southwestern China Region, the Northwestern China Region, and the Tibetan Plateau Region. Priority environmental problems of each EMR were discussed. The main contribution of this study is that it develops a novel methodological framework for EMRZ integrating qualitative and quantitative methodologies, and considers the spatial contiguity of each EMR and the spatial integrity of each administrative unit. Future research will focus on priority goals and establishment of suitable environmental management policies for each EMR based on known local environmental problems.

[Assessment of eco-environmental vulnerability of Hainan Island, China].

Based on the assessment method of environmental vulnerability constructed by SOPAC and UNEP, this paper constructed an indicator system from three sub-themes including hazard, resistance, and damage to assess the eco-environmental vulnerability of Hainan Island. The results showed that Hainan Island was suffering a middling level eco-environmental hazard, and the main hazards came from some intensive human activities such as intensive agriculture, mass tourism, mining, and a mass of solid wastes thrown by islanders and tourists. Some geographical characters such as larger land area, larger altitude range, integrated geographical form, and abundant habitat types endowed Hainan Island higher resistance to environmental hazards. However, disturbed by historical accumulative artificial and natural hazards, the Island ecosystem had showed serious ecological damage, such as soil degradation and biodiversity loss. Comprehensively considered hazard, resistance, damage, and degradation, the comprehensive environmental vulnerability of the Island was at a middling level. Some indicators showed lower vulnerability, but some showed higher vulnerability.

[Ecological quality of Beijing urban area from 1996 to 2005].

From the aspects of four ecological themes, i.e., ecological element, ecological process, ecological function and ecological destruction, an indicator framework including 16 indicators was developed to make an integrated assessment on the ecological quality of Beijing urban area. The weights of the indicators were determined by the methods of entropy weight, optimal state weight, and worst state weight, and the ecological element index (EEI), ecological process index (EPI), ecological function index (EFI), ecological destruction index (EDI), and composite ecological index (CEI) were computed by a weighted sum method and served as effective tools for analyzing the evolvement of the ecological quality of Beijing urban area from 1996 to 2005. The results showed that during the period of 1996-2005, the EEI of Beijing urban area did not display visible improvement and maintained a low level, far from the ideal state. The EPI and EFI increased dramatically, and approached to the ideal state in 2005. The EDI fluctuated within a low level, far from ideal state, and did not show an evolutionary trend. The CEI improved year after year, but was still low and did not reach the ideal state. The EPI, EFI, and CEI increased rapidly with economic development when the GDP per capita was less than US $ 3,000, but the decrease was decelerated after the GDP exceeded US $ 3,000. The EEI and EDI were less affected by economic development, but mainly restrained by the natural conditions and global and regional eco-environmental evolvement.

[Connotation of ecological integrity and its assessment methods: a review].

Ecological integrity is the capability to support and maintain a balanced, integrative and adaptive biologic system, having the full range of elements and processes expected in the natural habitats of a region. Assessment of ecological integrity has great significance for preventing sensitive nature habitats from human disturbance. The theory of dissipative structures suggests that the stressors from human activities, as well as the biological, physical and chemical integrity and ecosystem function that reflect the ability of self-organizing, can well indicate the integrity of an ecosystem. This paper summarized the experiential indicators for assessing the integrity of aquatic and terrestrial ecosystems and the stressors from human disturbance, and discussed the methods for selecting priority indicators and comprehensive assessment in actual assessment programs. The prospects of further study were discussed, according to some issues existed in published researches.