Redistribution of Electron Equivalents between Magnetite and Aqueous Fe2+ Induced by a Model Quinone Compound AQDS

The complex interactions between magnetite and aqueous Fe²⁺ (Fe²⁺_(aq)) pertain to many biogeochemical redox processes in anoxic subsurface environments. The effect of natural organic matter, abundant in these same environments, on Fe²⁺_(aq)-magnetite interactions is an additional complex that remains poorly understood. We investigated the influence of a model quinone molecule anthraquinone-2,6-disulfonate (AQDS) on Fe²⁺_(aq)-magnetite interactions by systematically studying equilibrium Fe²⁺_(aq) concentrations, rates and extents of AQDS reduction, and structural versus surface-localized Fe(II)/Fe(III) ratios in magnetite under different controlled experimental conditions. The equilibrium concentration of Fe²⁺_(aq) in Fe²⁺-amended magnetite suspensions with AQDS proportionally changes with solution pH or initial AQDS concentration, but independent of magnetite loadings through the solid concentrations that were studied here. The rates and extents of AQDS reduction by Fe²⁺-amended magnetite proportionally increased with solution pH, magnetite loading, and initial Fe²⁺_(aq) concentration, which correlates with the corresponding change of reduction potentials for the Fe²⁺-magnetite system. AQDS reduction by surface-associated Fe(II) in the Fe²⁺-magnetite suspensions induces solid-state migration of electron equivalents from particle interiors to the near-surface region and the production of nonmagnetic Fe(II)-containing species, which inhibits Fe²⁺_(aq) incorporation or electron injection into the magnetite structure. This study demonstrates the significant influence of quinones on reductive activity of the Fe²⁺-magnetite system.

Solving the mystery of vanishing rivers in China

A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km2 was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of Rivers and Lakes in China. As a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.

Author Correction: Actinia-like multifunctional nanocoagulant for single-step removal of water contaminants

In the version of the Supplementary Information file originally published with this Article, the images used for Supplementary Fig. 4 were incorrect and have now been replaced. This does not affect the results of the Article.

[The overview of the development of modern burn surgery in China]

Chinese modern burn surgery belongs to the western medicine system. From 1930s, the knowledge of modern burn surgery spread over China. Its development had experienced four stages: enlightening stage, exploratory stage, mature stage, and remodeling stage. Before the 1950s, medical personnel began to study those knowledges. The clinical treatment developed slowly and had little experience. From the 1950s to 1960s, Chinese burn surgery professionals made the painstaking exploration and accumulated rich clinical experiences. The success of severe burns treatment attracted worldwide attention. From the 1970s to the mid-1990s, as the regulations of burn diagnosis and treatment established in China, the clinical treatment developed widely. The world's leading therapeutic effects have achieved. The professional education system has been founded, and the professional societies have created. Those made medical personnel can access the scientific research achievement. Therefore, the leading talents emerged. Chinese modern burn surgery entered a mature stage. Since the late-1990s, Chinese modern burn surgery entered a remodeling stage. Besides increasing the cure rate and decrease disability rate of burn gradually, Chinese modern burn surgery need solve new problems such as that standardization of diagnosis and treatment sets up, the scope of diagnosis and treatment expands, professional training improves, etc.

Actinia-like multifunctional nanocoagulant for single-step removal of water contaminants

Current technologies for water purification are limited by their contaminant-specific removal capability, requiring multiple processes to meet water quality objectives. Here we show an innovative biomimetic micellar nanocoagulant that imitates the structure of Actinia, a marine predator that uses its tentacles to ensnare food, for the removal of an array of water contaminants with a single treatment step. The Actinia-like micellar nanocoagulant has a core-shell structure and readily disperses in water while maintaining a high stability against aggregation. To achieve effective coagulation, the nanocoagulant everts its configuration, similar to Actinia. The shell hydrolyses into 'flocs' and destabilizes and enmeshes colloidal particles while the core is exposed to water, like the extended tentacles of Actinia, and adsorbs the dissolved contaminants. The technology, with its ability to remove a broad spectrum of contaminants and produce high-quality water, has the potential to be a cost-effective replacement for current water treatment processes.

Maximization of current efficiency for organic pollutants oxidation at BDD, Ti/SnO2-Sb/PbO2, and Ti/SnO2-Sb anodes

Whereas electrochemical oxidation is noted for its ability to degrade bio-refractory organics, it has also been incorrectly criticized for excessive energy consumption. The present paper rectifies this misunderstanding by demonstrating that the energy actually consumed in the degradation process is much less than that wasted in the side reaction of oxygen evolution. To minimize the side reaction, the possible highest instantaneous current efficiency (PHICE) for electrochemical oxidation of phenol at Boron-doped Diamond (BDD), Ti/SnO₂-Sb/PbO₂ (PbO₂), and Ti/SnO₂-Sb (SnO₂) anodes has been investigated systematically, and found to reach almost 100% at the BDD anode compared with 23% at the PbO₂ anode and 9% at the SnO₂ anode. The significant discrepancy between PHICE values at the various anodes is interpreted in terms of different existing forms of hydroxyl radicals. For each anode system, the PHICEs are maintained experimentally using a computer-controlled exponential decay current mode throughout the electrolysis process. For applications, the minimized energy consumption is predicted by response surface methodology, and demonstrated for the BDD anode system. Consequently, almost 100% current efficiency is achieved (for a relatively meagre energy consumption of 17.2 kWh kgCOD^-1) along with excellent COD degradation efficiency by optimizing the initial current density, flow rate, electrolysis time, and exponential decay constant. Compared with galvanostatic conditions, over 70% of the energy is saved in the present study, thus demonstrating the great potential of electrochemical oxidation for practical applications.

Removal of prometryn from hydroponic media using marsh pennywort (Hydrocotyle vulgaris L.)

The aquatic plant Hydrocotyle vulgaris was evaluated for its efficacy in removing prometryn from nutrient solution. Under optimized experimental conditions, up to 94.0% of the initial prometryn was removed from the hydroponic culture medium by H. vulgaris in 30 days. The concentration of prometryn decreased from the initial level of 0.55 ± 0.013 mg/L to 0.036 ± 0.001 mg/L at the end of the experimental period. The removal kinetics followed first-order kinetic equation (Ct = 0.4569e^-0.09t). Half-life (t_1/2) of prometryn was greatly shortened from 27.16 days (without plant) to 5.58 days (with H. vulgaris). Approximately 22% of the initial prometryn residue was found in H. vulgaris tissue, while 11.7% was degraded by the plant in 30 days. The metabolites of prometryn detected were 2,4-diamino-1,3,5-triazine (in the hydroponic culture medium) and 2,4,6-trihydroxy-1,3,5-triazine (in plant tissue) after 30 days. The results indicate that H. vulgaris can be used for phytoextraction of prometryn and could potentially be effective in removing other s-trazine pesticides from contaminated aquatic ecosystems.

Validation of a revised Mandarin Chinese language version of the Postoperative Quality of Recovery Scale

The aim of the study was to validate a revised Mandarin version of the Postoperative Quality of Recovery Scale (PostopQRS) and to apply the revised version in a Chinese population. In a prospective design, bilingual volunteers completed the scale at baseline, day one, day seven, and day 14 in both languages, with the order of language and parallel forms randomised. In addition, lung cancer patients undergoing open or video-assisted thoracoscopic surgery (VATS) completed the Mandarin version prior to surgery, day one, day three, day seven, day 14, one month, and three months postoperatively. Sixty-eight volunteers participated in the validation part of the study and in the clinical application, 93 lung cancer patients were included. The scores in the Mandarin version were equal to the English version in all domains at all timepoints including the word generation task, when the Mandarin morpheme was included in any part of the Mandarin word. However, Mandarin scores were lower in the word generation task if the morpheme was only included in the first part of the word. In addition, the Mandarin version was able to identify lower rates of overall recovery (<i>P</i> <0.01), nociceptive (<i>P</i> <0.01), emotive (<i>P</i> <0.01), and activities of daily living recovery (<i>P</i>=0.02) after open surgery compared to after VATS. The revised Mandarin version is equivalent to the English version for the cognitive domain, if morpheme substitution for the word generation task is allowed as any part of the word, and it is able to discriminate quality of recovery in Chinese patients.

Dominant role of ammonia-oxidizing bacteria in nitrification due to ammonia accumulation in sediments of Danjiangkou reservoir, China

Surface sediments are the inner source of contaminations in aquatic systems and usually maintain aerobic conditions. As the key participators of nitrification process, little is known about the activities and contributions of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the surface sediments. In this study, we determined the net and potential nitrification rates and used 1-octyne as an AOB specific inhibitor to detect the contributions of AOA and AOB to nitrification in surface sediments of Danjiangkou reservoir, which is the water source area of the middle route of South-to-North Water Diversion Project in China. Quantitative PCR and Illumina high-throughput sequencing were used to evaluate the abundance and diversity of the amoA gene. The net and potential nitrification rates ranged from 0.42 to 1.93 and 2.06 to 8.79 mg N kg^-1 dry sediments d^-1, respectively. AOB dominated in both net and potential nitrification, whose contribution accounted for 52.7-78.6% and 59.9-88.1%, respectively. The cell-specific ammonia oxidation rate calculation also revealed the cell-specific rates of AOB were higher than that of AOA. The Spearman's rank correlation analysis suggested that ammonia accumulation led to the AOB predominant role in net nitrification activity, and AOB abundance played the key role in potential nitrification activity. Furthermore, phylogenetic analysis suggested AOB were predominantly characterized by the Nitrosospira cluster, while AOA by the Nitrososphaera and Nitrososphaera sister clusters. This study will help us to better understand the contributions and characteristics of AOA and AOB in aquatic sediments and provide improved strategies for nitrogen control in large reservoirs.

A duodecennial national synthesis of antibiotics in China's major rivers and seas (2005-2016)

The occurrence of 94 antibiotics in water and sediments from seven major rivers and four seas in China during 2005-2016 was reviewed. Twelve antibiotics were most frequently detected in both water and sediment samples, including 3 sulfonamides (SAs), 2 tetracyclines (TCs), 4 fluoroquinolones (FQs), and 3 macrolides (MLs). Their median concentrations were below 100ng/L and 100ng/g in river water and sediments, respectively. The highest median concentrations were found in water (1.30-176ng/L) and sediments (0.15-110ng/g) in the Hai River, due to its larger population density, higher consumption of antibiotics, and lower water flow. The concentrations of TCs and FQs were higher in the Pearl River sediments, due to their extensive use in aquaculture. The Yangtze River showed lower median concentrations of antibiotics in both water (1.33-17.3ng/L) and sediments (0.31-14.8ng/g), resulting from its larger catchment size, and higher precipitation and water flow. The Yellow River exhibited lower median concentrations of antibiotics in sediments (0.04-9.04ng/g), probably due to low organic matter content in sediments and high suspended particle content in water. Organic carbon normalized distribution coefficients (K_oc) of antibiotics were positively correlated with the octanol/water partition coefficients (K_ow) of antibiotics, and the correlation for MLs with a macrocyclic lactone ring was different from that of SAs, FQs, and TCs, likely due to their much larger molecular size. Among China's major rivers, the Hai River had the highest ecotoxicological risk from antibiotics to algae, invertebrate, fish, and plant.

Integrated biogeography of planktonic and sedimentary bacterial communities in the Yangtze River

BACKGROUND

Bacterial communities are essential to the biogeochemical cycle in riverine ecosystems. However, little is presently known about the integrated biogeography of planktonic and sedimentary bacterial communities in large rivers.

RESULTS

This study provides the first spatiotemporal pattern of bacterial communities in the Yangtze River, the largest river in Asia with a catchment area of 1,800,000 km2. We find that sedimentary bacteria made larger contributions than planktonic bacteria to the bacterial diversity of the Yangzte River ecosystem with the sediment subgroup providing 98.8% of 38,906 operational taxonomic units (OTUs) observed in 280 samples of synchronous flowing water and sediment at 50 national monitoring stations covering a 4300 km reach. OTUs within the same phylum displayed uniform seasonal variations, and many phyla demonstrated autumn preference throughout the length of the river. Seasonal differences in bacterial communities were statistically significant in water, whereas bacterial communities in both water and sediment were geographically clustered according to five types of landforms: mountain, foothill, basin, foothill-mountain, and plain. Interestingly, the presence of two huge dams resulted in a drastic fall of bacterial taxa in sediment immediately downstream due to severe riverbed scouring. The integrity of the biogeography is satisfactorily interpreted by the combination of neutral and species sorting perspectives in meta-community theory for bacterial communities in flowing water and sediment.

CONCLUSIONS

Our study fills a gap in understanding of bacterial communities in one of the world's largest river and highlights the importance of both planktonic and sedimentary communities to the integrity of bacterial biogeographic patterns in a river subject to varying natural and anthropogenic impacts.

Microbial community compositions in different functional zones of Carrousel oxidation ditch system for domestic wastewater treatment

The microbial community diversity in anaerobic-, anoxic- and oxic-biological zones of a conventional Carrousel oxidation ditch system for domestic wastewater treatment was systematically investigated. The monitored results of the activated sludge sampled from six full-scale WWTPs indicated that Proteobacteria, Chloroflexi, Bacteroidetes, Actinobacteria, Verrucomicrobia, Acidobacteria and Nitrospirae were dominant phyla, and Nitrospira was the most abundant and ubiquitous genus across the three biological zones. The anaerobic-, anoxic- and oxic-zones shared approximately similar percentages across the 50 most abundant genera, and three genera (i.e. uncultured bacterium PeM15, Methanosaeta and Bellilinea) presented statistically significantly differential abundance in the anoxic-zone. Illumina high-throughput sequences related to ammonium oxidizer organisms and denitrifiers with top50 abundance in all samples were Nitrospira, uncultured Nitrosomonadaceae, Dechloromonas, Thauera, Denitratisoma, Rhodocyclaceae (norank) and Comamonadaceae (norank). Moreover, environmental variables such as water temperature, water volume, influent ammonium nitrogen, influent chemical oxygen demand (COD) and effluent COD exhibited significant correlation to the microbial community according to the Monte Carlo permutation test analysis (p < 0.05). The abundance of Nitrospira, uncultured Nitrosomonadaceae and Denitratisoma presented strong positive correlations with the influent/effluent concentration of COD and ammonium nitrogen, while Dechloromonas, Thauera, Rhodocyclaceae (norank) and Comamonadaceae (norank) showed positive correlations with water volume and temperature. The established relationship between microbial community and environmental variables in different biologically functional zones of the six representative WWTPs at different geographical locations made the present work of potential use for evaluation of practical wastewater treatment processes.

Optical property of dissolved organic matters (DOMs) and its link to the presence of metal ions in surface freshwaters in China

It is believed that dissolved organic matter (DOM) plays an important role in carrying metal ions through global cycle and distribution, while this point has not yet been elucidated clearly as DOM is extremely heterogeneous and site-specific. In this study, optical properties of DOM in 53 surface freshwater sites all over China were recorded by UV-Vis absorbance spectroscopy in pH range 3-11. The subtle processes of protonation-deprotonation of DOM were quantified by tracking the changes of DOM spectra. The binding capacities of DOMs-binding sites and affinity constants-were interpreted by introducing a spectral parameter, differential log-transformed differential absorbance at 400 nm (DlnA₄₀₀) in combination with Non-Ideal Competitive Adsorption (NICA) Model. It is found that the presence of dissolved Zn, Hg and Ni in the examined waters show strong correlation with total binding sites in DOMs. However, the presence of some other metals with high affinities to DOM, e.g. Cu, Fe and so on, have not demonstrated strong correlation with the total binding sites in DOMs. This indicates the presence of these metals may be seriously influenced by other factors besides DOM. This study demonstrates that the spectroscopic titration approach could potentially provide more structure-specific in situ information about DOM and help to understand the role of DOM in the speciation and bioavailability of toxic metal ions.