Controlled synthesis and photocatalytic hydrogen evolution activities of cobalt carbides with different phase compositions.

Cobalt carbides are emerging as promising materials for various magnetic and catalytic applications. However, exploring dedicated cobalt carbides with optimal catalytic properties via adjusting phase compositions remains a significant challenge. Herein, three different cobalt carbides, CoxC (Co2C-Co3C), Co2C-Co, and Co3C, were successfully prepared using a facile one-pot green method. The phase compositions of cobalt carbides could be easily controlled by varying the cobalt-based precursors and carbon sources. More remarkably, three different cobalt carbides could serve as reduction cocatalysts decorated CdS for improved hydrogen production under visible light. Intriguingly, the obtained Co3C/CdS nanocomposite displayed the highest photocatalytic hydrogen evolution activity among the three composites and superior photocatalytic stability. This work provides a fundamental approach to tuning the photocatalytic properties of cobalt carbides for energy conversion fields.

Enrichment, bioaccumulation and human health assessment of organochlorine pesticides in sediments and edible fish of a plateau lake.

The organochlorine pesticides (OCPs) are with features of persistence, high toxicity, bioaccumulation and adverse impact on ecosystems and human beings. Although OCPs pollutions have been observed in the plateau lakes, comprehensive understandings in the distribution characteristics and human health risks of OCPs in these valuable but fragile ecosystems are limited. We here investigated the distribution, bioaccumulation process and health risks of OCPs in the Jianhu lake, a representative plateau lake in China. The endrin ketone, endrin aldehyde and heptachlor were the most dominant species in surface and columnar sediments. Their total contents ranged between 0 ~ 1.92 × 103 ng·g-1. The distribution of OCPs in sediment cores combined with chronology information indicated that the fast accumulation of OCPs happened during the last decades. Combining the distribution features of OCPs in different sources with mixing model results of carbon isotope (δ13C), farming area was identified as the main source (46%), and the OCPs were transported to lake by inflow-rivers (37%). The enrichment of OCPs in sediments caused considerable bioaccumulation of OCPs in local fish (∑OCPs 0-3199.93 ng·g-1, dw) with the bio-sediment accumulation factor (BSAF) ranging from ND to 9.41. Moreover, growing time was another key factor governing the accumulation in specific species (Carassius auratus and Cyprinus carpio). Eventually, the carcinogenic risk index (CRI) and exposure risk index (ERI) of the endrin category and aldrin exceeded the reference value, indicating relatively high health risks through consumption of fish. Overall, this study systematically illustrated the bioaccumulation process and health risks of OCPs in the typical plateau lake, providing theoretical support for the better protection of this kind of lakes.

Fecal-related anthropogenic sources are key determinants of lake microbiomes through microbial source tracking.

Lake microbiomes are essential indicators of lake health and are strongly influenced by allochthonous microbial communities from various sources within the watershed. However, quantifying the contributions of multiple inputs to lake microbiomes is challenging because of the complex nature of river‒lake systems and the presence of many untraceable sources. Here, Jianhu Lake‒‒a geographically simple and closed plateau lake in southwestern China, was surveyed to disentangle the contributions of five distinct sources (three input rivers that receive town sewage, stormwater runoff, and creek spring water, as well as two nonpoint sources, duck ponds and dry farmland) to the overall lake microbiomes. We found that feces-loading sources, namely town sewage and duck aquaculture, accounted for 48.7% of the total variations in lake microbiomes. In contrast, the combined contribution of the remaining three sources amounted to 13.21%, despite these less-influential sources (e.g., stormwater runoff) may introduce an even larger volume of allochthonous materials into the lake. In addition, approximately 38.1% of the variations in the lake microbiomes were attributed to unknown sources. Sewage effluents also caused a significant loss of lake microbial diversity, and there was a tendency for large-scale microbial homogeneity in lake sediments that resembled those from duck ponds. We then used a targeted approach to track host-specific fecal pollution, and found that human feces were the primary source, followed by ruminant and chicken/duck feces, all of which can be successfully traced back to the feces-loading sources. In our further modelling of sediment transport from three rivers into the whole lake, we observed a significant relationship between sediment accumulation and adsorbed microorganisms only for the sewage-receiving river. Together, lines of evidence indicate that both point and nonpoint fecal-related anthropogenic sources possess discriminatory power for shaping microbial geographic patterns of the lake, posing threats to the survival of local indigenous lake microbiomes.

[Co-occurrence of Tetracycline Antibiotic Resistance Genes and Microbial Communities in Plateau Wetlands Under the Influence of Human Activities].

The widespread use of antibiotics has led to a large number of antibiotics entering the environment, to which microorganisms have become resistant. In recent years, with the intensification of human activities in the plateau region, the occurrence and migration of antibiotic resistance genes (ARGs) in plateau wetlands have attracted considerable attention. Here, we selected the Caohai National Wetland Park, located in the Yunnan-Guizhou Plateau, as our study area. The contents of tetracyclines, sulfonamides, quinolones, and macrolides in sediments from the upstream (the pristine habitat near the spring eye) and downstream (the sewage discharge outlet of residents) areas of the river in the park were analyzed. Among them, the detection content of tetracycline antibiotics was 103.65-2185 µg·kg-1, which was the highest antibiotic detection content. To further investigate the occurrence characteristics and influencing factors of tetracycline resistance genes, the influence of environmental factors, bacterial community structure, and pathogenic bacteria on tetracycline ARGs under the influence of human activities were revealed via correlation analysis and network analysis. The results showed that a total of 15 tetracycline resistance genes were detected in the upstream and downstream sediments. Among them, seven resistance genes including tetPA, tetD, and tetPB were detected in the upstream, and 13 resistance genes such as tetPA, tetE, tetM, and tetX were detected in the downstream. The abundance of eight new resistance genes in the downstream accounted for 43.44% of the downstream genes. The tetracycline-like antibiotics and soil physicochemical indicators (i.e., available phosphorus, total organic carbon, nitrate nitrogen, and total phosphorus) were the main environmental factors affecting the distribution of tetracycline ARGs. Additionally, the bacteria detected in the upstream and downstream sediments belonged to 64 bacterial phyla, among which Proteobacteria, Firmicutes, and Bacteroidota were the main phyla affecting the abundance of tetracycline ARGs; meanwhile, 27 pathogenic bacteria were detected in the upstream and downstream sediments. Network analysis showed that the correlation between the eight new resistance genes and pathogens in the downstream area accounted for 70% of the network connectivity, and Listeria monocytogenes, Enterococcus faecalis, and Bacteroides vulgatus were identified as potential hosts for the transmission of tetracycline ARGs. Compared to the pristine habitat, the discharge of domestic sewage introduced large amounts of antibiotics and also changed the microenvironment and microbial community structure of the river wetland. Additionally, it increased the species of ARGs in sediments, which promoted the spread and transmission of ARGs among microorganisms and even pathogens.

Long-term deposition records of microplastics in a plateau lake under the influence of multiple natural and anthropogenic factors.

Microplastic accumulation in the lake aquatic environment has attracted worldwide attention, but the long-term deposition characteristics and influencing factors of microplastics are not clear. Hence, we attempted to analyze the factors that influence the accumulation of microplastics during the process of natural environmental change and social development through the method of the sedimentological approach. In this investigation, the chronological sequence of sediment core was set up based on lead-210 composition to study microplastic accumulation rates in a plateau lake, Jianhu Lake. For the first time, the records of microplastic deposition were analyzed combined with multiple anthropogenic and natural factors, including 4 natural and 17 social factors to reveal the influence of natural processes and social development on microplastic abundances. The results showed that sediments were highly contaminated by microplastics, and the mean abundance of microplastics in the sediment cores of Jianhu Lake was 924 ± 427 particles/kg, and showed a gradually increasing trend from the bottom (25 to 30 cm) to surface layer (0 to 5 cm). Blue and black were the main colors of microplastics, and the average proportion of wirelike microplastics was 63 %. Additionally, the polymer type of microplastic was mainly rayon, the surface morphology of different polymer types was disparate, and various elements enriched on the surface of microplastics were also detected. In the past 70 years, the deposition rate of microplastics in Jianhu Lake maintained the trend of continuous growth, and the abundance of microplastics is projected to be 448 to 3017 and 513 to 3670 particles/kg by 2035 and 2050, respectively. What is more, there are significant correlations among multiple natural and anthropogenic factors and microplastic deposition, as well as microplastic polymer species.

The complete chloroplast genome of Beesia deltophylla (Ranunculaceae).

Beesia deltophylla is an endemic and rare species only distributed in Xizang, China. The chloroplast genome of B. deltophylla is 157,397 bp in length, with 112 encoded genes including 78 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Phylogenetic reconstruction has confirmed the placement of B. deltophylla as sister to B. calthifolia. These two species formed a clade closely to a Japan endemic species Anemonopsis macrophylla.

Spatial distribution and ecological assessment of nickel in sediments of a typical small plateau lake from Yunnan Province, China.

Nickel (Ni) in small plateau lake sediments plays an important role in influencing the quality of lake ecosystems with a high degree of endemism and toxicity. This paper focuses on the spatial distribution and ecological risks of nickel in the sediments of Jianhu Lake, a small plateau lake in China, and the influence of pH and total organic carbon (TOC) on nickel concentrations. The results showed that average total nickel concentrations were 138.99 ± 57.57 mg/kg (n = 38) and 184.31 ± 92.12 mg/kg (n = 60) in surface sediments (0-10 cm top layer) and sediment cores (0-75 cm depth), respectively, and that the residual fraction was the main form of nickel. Simultaneously, through a semivariogram model, strong spatial dependence among pH, TOC, and the oxidizable fraction was revealed, whereas total nickel, exchangeable and the weak acid soluble fraction, reducible fraction, and residual fraction showed moderate spatial dependence. The vertical distribution revealed that nickel accumulated mainly in the bottom 5 cm (70-75 cm) of the sediment layer and that the pH was higher there, whereas TOC was concentrated mainly in the top 5 cm of sediment. Using geoaccumulation and a potential ecological risk index, moderate nickel pollution and moderate risk levels were found in most surface sediments, but moderate nickel pollution and high risk levels were observed in most sediment cores. In addition, pH and TOC were found to have a strong effect on the distribution and concentration of nickel and its fractions in the small plateau lake. In summary, nickel posed a certain degree of pollution and ecological risk, which deserves attention in the sediments of small plateau lakes.

[Effects of plant community and soil properties on soil bacterial community in Bitahai Wetland, Southwest China]. / 植物群落和土壤理化性质对碧塔海湿地土壤细菌群落的影响.

Soil microorganism was the engine of the migration and transformation of biological elements in the soil-plant system of wetland ecosystems. Exploring the relationship between plant community, soil properties, and spatial structure with soil microorganisms is the key to maintain the health and stability of wetlands. In order to examine the effects of plant community, soil properties, and spatial structure on the bacterial community in wetlands, we used two-way indicator species analysis (TWINSPAN) to classify plant communities from 35 samples collected in Bitahai Wetland. We measured microbial community composition at the surface soil of the samples using high-throughput sequencing technology, and analyzed the relationship among plant community, soil pro-perties and spatial structure with bacterial community. The results showed that plant communities could classified into three different types by TWINSPAN. The physiognomy and structure of plant communities in same community type were relatively consistent. We found that quantitative classification had good applicability in vegetation classification of plateau wetland ecosystem. Acidobacteriota (21.0%), Chloroflexi (15.5%), Proteobacteria (15.3%) and Bacteroidetes (10.1%) had higher population densities (≥10%) in Bitahai Wetland. Analysis of similarities (ANOSIM) showed that different plant community types differed significantly in bacterial community composition, suggesting that plant communities could affect bacterial community. Cano-nical correspondence analysis (CCA) results showed that plant diversity, soil water content (SWC), pH, iron (Fe) and spatial structure were the dominated factors that significantly affecting bacterial community. The variance partitioning analysis (VPA) results showed that bacterial community was affected by single environment factors and their interactions. Our results highlighted that bacterial community is shaped by plant community, soil properties and spatial structure, with their effects being indivisible.

Swimming Performance of the Frog-Inspired Soft Robot.

This article presents a frog-inspired swimming soft robot whose joints are articulated pneumatic soft actuators. The soft actuator is designed and prepared by studying the biological structure and limb movement characteristics of frogs. A schematic limb motion diagram of the robot is established based on the kinematic model, and the design scheme is determined by a combined control system. The torso size is 0.175 × 0.100 × 0.060 m, which realizes frog-inspired swimming robot miniaturization. The experimental results show that the average propulsion speed during linear motion is 0.075 m/s, and the average turning speed is 15°/s. The rationality of the robot structural design and correctness of the control system are verified by prototype experiments.