Optimizing Robotic Mobile Fulfillment Systems for Order Picking Based on Deep Reinforcement Learning.

Robotic Mobile Fulfillment Systems (RMFSs) face challenges in handling large-scale orders and navigating complex environments, frequently encountering a series of intricate decision-making problems, such as order allocation, shelf selection, and robot scheduling. To address these challenges, this paper integrates Deep Reinforcement Learning (DRL) technology into an RMFS, to meet the needs of efficient order processing and system stability. This study focuses on three key stages of RMFSs: order allocation and sorting, shelf selection, and coordinated robot scheduling. For each stage, mathematical models are established and the corresponding solutions are proposed. Unlike traditional methods, DRL technology is introduced to solve these problems, utilizing a Genetic Algorithm and Ant Colony Optimization to handle decision making related to large-scale orders. Through simulation experiments, performance indicators-such as shelf access frequency and the total processing time of the RMFS-are evaluated. The experimental results demonstrate that, compared to traditional methods, our algorithms excel in handling large-scale orders, showcasing exceptional superiority, capable of completing approximately 110 tasks within an hour. Future research should focus on integrated decision-making modeling for each stage of RMFSs and designing efficient heuristic algorithms for large-scale problems, to further enhance system performance and efficiency.

A temperature-induced chitosanase bacterial cell-surface display system for the efficient production of chitooligosaccharides.

OBJECTIVE: To establish a temperature-induced chitosanase bacterial cell-surface display system to produce chitooligosaccharides (COSs) efficiently for industrial applications. RESULTS: Temperature-inducible chitosanase CSN46A bacterial surface display systems containing one or two copies of ice nucleation protein (InaQ-N) as anchoring motifs were successfully constructed on the basis of Escherichia coli and named as InaQ-N-CSN46A (1 copy) and 2InaQ-N-CSN46A (2 copies). The specific enzyme activity of 2InaQ-N-CSN46A reached 761.34 ± 0.78 U/g cell dry weight, which was 45.6% higher than that of InaQ-N-CSN46A. However, few proteins were detected in the 2InaQ-N-CSN46A hydrolysis system. Therefore, 2InaQ-N-CSN46A had higher hydrolysis efficiency and stability than InaQ-N-CSN46A. Gel permeation chromatography revealed that under the optimum enzymatic hydrolysis temperature, the final products were mainly chitobiose and chitotriose. Chitopentaose accumulated (77.62%) when the hydrolysis temperature reached 60 °C. FTIR and NMR analysis demonstrated that the structures of the two hydrolysis products were consistent with those of COSs. CONCLUSIONS: In this study, chitosanase was expressed on the surfaces of E. coli by increasing the induction temperature, and chitosan was hydrolysed directly without enzyme purification steps. This study provides a novel strategy for industrial COS production.

Uptake and Translocation of Perfluorooctanoic Acid (PFOA) and Perfluorooctanesulfonic Acid (PFOS) by Wetland Plants: Tissue- and Cell-Level Distribution Visualization with Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) and Transmission Electron Microscopy Equipped with Energy-Dispersive Spectroscopy (TEM-EDS).

Perfluoroalkyl substances (PFASs) are persistent chemicals in the environment. So far, little is known about their uptake potential in wetland plants. Here, we investigated the uptake and translocation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in eight common wetland plants, namely, Canna indica (Ci), Thalia dealbata (Td), Cyperus alternifolius (Ca), Phragmites australis (Pa), Arundo donax (Ad), Pontederia cordata (Pc), Cyperus papyrus (Cp), and Alisma orientale (Ao) by hydroponic experiments and visualized their tissue- and cell-level distribution with desorption electrospray ionization mass spectrometry (DESI-MS) and transmission electron microscopy equipped with energy-dispersive spectroscopy (TEM-EDS). The results showed that the PFASs accumulated in plants accounted for 1.67-16.7% of the total mass spiked into the hydroponic systems, and PFOS accumulated largely in roots (48.8-95.8%), while PFOA was stored mostly in the aboveground part (29.3-77.4%). DESI-MS and TEM-EDS analysis showed that PFASs in Ci, Td, Pa, and Ca were transported from the hydroponic solution to the root cortex via both apoplastic (e.g., across cell walls and/or intercellular spaces) and symplastic routes (e.g., across plasma membranes or via plasmodesmata) and further to the vascular bundle via symplastic route in Td and Pa and via both routes in Ci and Ca. These two chemicals were transported from roots to stems mainly through the cortex in Td and through both the cortex and vascular bundles in Ci and Ca.

Click-Chemistry-Mediated Rapid Microbubble Capture for Acute Thrombus Ultrasound Molecular Imaging.

Bioorthogonal coupling chemistry has been studied as a potentially advantageous approach for molecular imaging because it offers rapid, efficient, and strong binding, which might also benefit stability, production, and chemical conjugation. The inverse-electron-demand Diels-Alder reaction between a 1,2,4,5-tetrazine and trans-cyclooctene (TCO) is an example of a highly selective and rapid bioorthogonal coupling reaction that has been used successfully to prepare targeted molecular imaging probes. Here we report a fast, reliable, and highly sensitive approach, based on a two-step pretargeting bioorthogonal approach, to achieving activated-platelet-specific CD62p-targeted thrombus ultrasound molecular imaging. Tetrazine-modified microbubbles (tetra-MBs) could be uniquely and rapidly captured by subsequent click chemistry of thrombus tagged with a trans-cyclooctene-pretreated CD62p antibody. Moreover, such tetra-MBs showed great long-term stability under physiological conditions, thus offering the ability to monitor thrombus changes in real time. We demonstrated for the first time that a bioorthogonal targeting molecular ultrasound imaging strategy based on tetra-MBs could be a simple but powerful tool for rapid diagnosis of acute thrombosis.

Simulating runoff changes and evaluating under climate change using CMIP6 data and the optimal SWAT model: a case study.

This study examines the influence of climate change on hydrological processes, particularly runoff, and how it affects managing water resources and ecosystem sustainability. It uses CMIP6 data to analyze changes in runoff patterns under different Shared Socioeconomic Pathways (SSP). This study also uses a Deep belief network (DBN) and a Modified Sparrow Search Optimizer (MSSO) to enhance the runoff forecasting capabilities of the SWAT model. DBN can learn complex patterns in the data and improve the accuracy of runoff forecasting. The meta-heuristic algorithm optimizes the models through iterative search processes and finds the optimal parameter configuration in the SWAT model. The Optimal SWAT Model accurately predicts runoff patterns, with high precision in capturing variability, a strong connection between projected and actual data, and minimal inaccuracy in its predictions, as indicated by an ENS score of 0.7152 and an R2 coefficient of determination of 0.8012. The outcomes of the forecasts illustrated that the runoff will decrease in the coming years, which could threaten the water source. Therefore, managers should manage water resources with awareness of these conditions.

Clinical performance and utility of a noninvasive urine-based methylation biomarker: TWIST1/Vimentin to detect urothelial carcinoma of the bladder.

Traditional clinical modalities for diagnosing bladder urothelial carcinoma (BUC) remain limited due to their invasive nature, significant costs, discomfort associated with cystoscopy, and low sensitivity to urine cytology. Therefore, there is an urgent need to identify highly sensitive, specific, and noninvasive biomarkers for the early detection of this neoplasm. Hypermethylated TWIST1/Vimentin promoter may be a noninvasive biomarker using urine sample. We assessed the TWIST1/Vimentin promoter methylation status in urine samples using the Methylated Human TWIST1 and Vimentin Gene Detection Kit (Jiangsu MicroDiag Biomedicine Co., Ltd., China). The samples were collected from five groups: group 1 consisted of patients with BUC, group 2 contained other patients with urologic tumors, group 3 consisted of patients with benign diseases (e.g., urinary tract infections, lithiasis, and benign prostatic hyperplasia), Group 4 included UTUC (upper tract urothelial carcinoma) patients and group5 comprised healthy individuals. The study encompassed 77 BUC patients, and we evaluated the degree of methylation of the TWIST1/Vimentin gene in their urine samples. Notably, TWIST1/Vimentin positivity was significantly elevated in comparison to groups 2, 3 and 5 (all p < 0.001) at a rate of 77.9%, but no significant difference was observed when compared to group 4. In the relationship between TWIST1/Vimentin methylation and clinicopathological features of BC patients from our center, we found there was no significant association between TWIST1/Vimentin status and proteinuria and/or hematuria, and hypermethylation of TWIST1 / VIM genes was found in both high and low tumor grade and in both non-muscle invasive bladder cancer (stages Tis, Ta, or T1) and muscle-invasive bladder cancer (stage T2 or above). In the multivariable analysis for cancer detection, a positive TWIST1/Vimentin methylation were significantly linked to a heightened risk of BC. Moreover, TWIST1/Vimentin promoter methylation demonstrated an ability to detect BUC in urine samples with a sensitivity of 78% and a specificity of 83%. Our findings reveal that hypermethylation of the TWIST1/Vimentin promoter occurs in bladder urothelial carcinoma, and its high sensitivity and specificity suggest its potential as a screening and therapeutic biomarker for urothelial carcinoma of the bladder.

Occurrence, distribution, and risk assessment of antibiotics in a typical aquaculture area around the Dongzhai Harbor mangrove forest on Hainan Island.

The trees of the Dongzhai Harbor mangrove forest suffer from antibiotic contamination from surrounding aquaculture areas. Despite this being one of the largest mangrove forests in China, few studies have focused on the antibiotic pollution status in these aquaculture areas. In the present study, the occurrence, distribution, and risk assessment of 37 antibiotics in surface water and sediment samples from aquaculture areas around Dongzhai Harbor mangrove forests were analyzed. The concentration of total antibiotics (∑antibiotics) ranged from 78.4 ng/L to 225.6 ng/L in surface water (except S14-A2) and from 19.5 ng/g dry weight (dw) to 229 ng/g dw in sediment. In the sediment, the concentrations of ∑antibiotics were relatively low (19.5-52.3 ng/g dw) at 75 % of the sampling sites, while they were high (95.7-229.0 ng/g dw) at a few sampling sites (S13-A1, S13D, S8D). The correlation analysis results showed that the Kd values of the 9 antibiotics were significantly positively correlated with molecular weight (MW), Kow, and LogKow. Risk assessment revealed that sulfamethoxazole (SMX) in surface water and SMX, enoxacin (ENX), ciprofloxacin (CFX), enrofloxacin (EFX), ofloxacin (OFX), and norfloxacin (NFX) in sediment had medium/high risk quotients (RQs) at 62.5 % and 25-100 %, respectively, of the sampling sites. The antibiotic mixture in surface water (0.06-3.36) and sediment (0.43-309) posed a high risk at 37.5 % and 66.7 %, respectively, of the sampling sites. SMX was selected as an indicator of antibiotic pollution in surface water to assist regulatory authorities in monitoring and managing antibiotic pollution in the aquaculture zone of Dongzhai Harbor. Overall, the results of the present study provide a comprehensive and detailed analysis of the characteristics of antibiotics in the aquaculture environment around the Dongzhai Harbor mangrove system and provide a theoretical basis for the source control of antibiotics in mangrove systems.

Application of environmental DNA metabarcoding to identify fish community characteristics in subtropical river systems.

Fish are vital in river ecosystems; however, traditional investigations of fish usually cause ecological damage. Extracting DNA from aquatic environments and identifying DNA sequences offer an alternative, noninvasive approach for detecting fish species. In this study, the effects of environmental DNA (eDNA), coupled with PCR and next-generation sequencing, and electrofishing for identifying fish community composition and diversity were compared. In three subtropical rivers of southern China, fish specimens and eDNA in water were collected along the longitudinal (upstream-downstream) gradient of the rivers. Both fish population parameters, including species abundance and biomass, and eDNA OTU richness grouped 38 sampling sites into eight spatial zones with significant differences in local fish community composition. Compared with order-/family-level grouping, genus-/species-level grouping could more accurately reveal the differences between upstream zones I-III, midstream zones IV-V, and downstream zones VI-VIII. From the headwaters to the estuary, two environmental gradients significantly influenced the longitudinal distribution of the fish species, including the first gradient composed of habitat and physical water parameters and the second gradient composed of chemical water parameters. The high regression coefficient of alpha diversity between eDNA and electrofishing methods as well as the accurate identification of dominant, alien, and biomarker species in each spatial zone indicated that eDNA could characterize fish community attributes at a level similar to that of traditional approaches. Overall, our results demonstrated that eDNA metabarcoding can be used as an effective tool for revealing fish composition and diversity, which is important for using the eDNA technique in aquatic field monitoring.

Abundance and characteristics of microplastics in the Wanquan River estuary, Hainan Island.

As the nexus where rivers and oceans meet, estuaries are vulnerable to microplastic (MP) pollution derived from rivers. However, few studies have focused on the pollution status of MPs in small estuarine areas. Here, the abundance and characteristics of MPs in surface water and sediment samples from a small estuary, the Wanquan River estuary, were studied. The average abundance of MPs was 6573 ± 2659 n/m3 in surface water and 1065 ± 696 n/kg dw in sediment samples from the Wanquan River estuary. Most of the MPs in water samples and sediments were red (92.9 % and 88.1 %) fragments (87.4 % and 95.5 %) with sizes <1.0 mm (90.8 % and 92.4 %) made up of antifouling paint particles (APPs) (83.5 % and 89.8 %), respectively. A significant positive correlation (p < 0.01) was found between the concentration of Cu2+ and the abundance of APPs in sediment samples from the Wanquan River estuary. The APPs in the sediments can act as a continuous source of toxic chemicals (e.g., Cu2+) to marine environments. The results of this study expand our knowledge about MP pollution in small estuaries, and the ecological risk of APPs in the Wanquan River estuary to aquatic organisms should not be ignored.

Perfluorooctanoic acid (PFOA)-induced alterations of biomolecules in the wetland plant Alismaorientale.

Perfluoroalkyl substances (PFASs) have been widely studied by researchers due to their environmental persistence, chemical stability and potential toxicity. Some researchers have reported the physiological and biochemical toxicity of PFASs on plants through traditional and innovative methods; however, the changes in biological macromolecules caused by PFASs are rarely studied. Here, Fourier transform infrared spectroscopy (FTIR) was used to study how exposure to perfluorooctanoic acid (PFOA) alters the structure and function of biomolecules of the wetland plant Alisma orientale. Biomass results showed that PFOA had negative effects on plant growth. FTIR results showed that PFOA could result in changes in the structures, compositions, and functions of lipids, proteins and DNA in plant cells. In the treatment groups, the ratios of CH3 to lipids and carbonyl esters to lipids increased compared with the control, while the ratios of CH2 to lipids and olefinicCH to lipids decreased, which indicated lipid peroxidation caused by PFOA exposure. Changes in the compositions and secondary structures of proteins were also found, which were indicated by the decreased ratio of amide I to amide II and the increased ratio of ß-sheet to α-helix in the treatment groups compared to the control. Moreover, PFOA affected the composition of DNA by promoting the B- to A-DNA transition. These results showed that the mechanism of PFOA toxicity toward plants at the biochemical level could be illustrated by FTIR.

Distribution and mass loads of xenoestrogens bisphenol a, 4-nonylphenol, and 4-tert-octylphenol in rainfall runoff from highly urbanized regions: A comparison with point sources of wastewater.

This study pays a special attention to three phenolic endocrine disrupting compounds (EDCs), - bisphenol A (BPA), 4-nonylphenol (4-NP), and 4-tert-octylphenol (4-t-OP) - that are present in urban environments, resultant of several anthropogenic activities that can be also carried through rainfall runoff. We investigated the distributions of BPA, 4-NP, and 4-t-OP in Pearl River basin and estimated the mass loads in rainfall runoff, wastewater treatment plant (WWTP) effluents, and industrial wastewater from urbanized Huizhou and Dongguan regions. These three phenolic EDCs were detected frequently in tributaries and mainstream of Dongjiang River with the maximum 4-NP concentrations of 14,540 ng/L in surface waters and 3088 ng/g in sediments. BPA showed high concentrations in rainfall runoff samples with maximum concentrations of 5873 and 2397 ng/L in Huizhou and Dongguan regions, respectively, while concentrations for 4-NP and 4-t-OP were detected at tens to hundreds of nanograms per liter. Mass loads of phenolic EDCs from rainfall runoff were 3-62 times higher than those of WWTP effluents, suggesting rainfall runoff is an important source of phenolic EDCs into receiving waters. Sources and tributaries showed median to high estrogenic risks, while low to median risks were found in mainstream, implying the source control should be focused.

Impacts of environmental factors on the food web structure, energy flows, and system attributes along a subtropical urban river in southern China.

Tropical and subtropical rivers are being subjected to multiple stressors from human disturbance (e.g., water pollution and habitat degradation). Understanding the relationship between environmental conditions and the river ecosystem is important for improving river management. We built 14 Ecopath models composed of 28 functional groups (trophic levels [TLs] of 1.0-3.8) along a subtropical urban river to explore the influence of environmental changes on system attributes. From headwaters to downstream, the model outputs showed that the transfer efficiency (TE), energy flow parameters, and ecosystem theory indices exhibited significant (P < 0.05) differences across a longitudinal gradient of disturbance, indicating heterogeneous attributes of local river segments. The high TE values of TLs I, II, and III separated the upper, middle, and lower reaches, respectively, which could be attributed to the shift in dominant consumption flows from upstream 'periphyton - aquatic insects - insectivorous fish' to midstream 'detritus - shrimp - crustaceavorous fish' and to downstream 'phytoplankton - filter-feeding invertebrates/fish'. Structural equation modelling was used to test the causal relationships among environmental variables and demonstrated that abiotic factors directly influenced biomass composition and indirectly influenced trophic networks. Water quality, including dissolved oxygen and flow velocity; habitat characteristics, such as riffles, cobble-gravel substrate, and seasonal floodplain; and biological indicators, including the relative contributions (%) of decapods, insectivorous fish, and insect scrapers to biomass composition, had significant (P < 0.05) positive impacts on system maturity (evaluated by omnivory, connectance, and cycling indices). In the future, it will be possible to evaluate the health of river ecosystems by monitoring representative environmental factors, which could be a cost-effective approach to system-level improvement.

Longitudinal pattern of resource utilization by aquatic consumers along a disturbed subtropical urban river: Estimating the relative contribution of resources with stable isotope analysis.

The utilization of food resources by aquatic consumers reflects the structure and functioning of river food webs. In lotic water systems, where food availability and predator-prey relationships vary with gradient changes in physical conditions, understanding diet assimilation by local communities is important for ecosystem conservation. In the subtropical Liuxi River, southern China, the relative contribution of basal resources to the diet assimilation of functional feeding groups (FFGs) was determined by stable carbon (13C) and nitrogen (15N) isotope analyses. The output of Bayesian mixing models showed that diatom-dominated periphyton (epilithic biofilm), aquatic C3 plants (submerged hydrophytes), and suspended particulate organic matter (SPOM) associated with terrestrial C3 plants contributed the most to the diet assimilation of FFGs in the upper, middle, and lower reaches, respectively. The relative contribution of consumer diet assimilation was weighted by the biomass (wet weight, g/m2) of each FFG to reflect resource utilization at the assemblage level. From the upper to the lower reaches, the spatial variation in the diet assimilation of fish and invertebrate assemblages could be summarized as a longitudinal decrease in periphyton (from 57%-76% to <3%) and an increase in SPOM (from <7% to 51%-68%) with a notable midstream increase in aquatic C3 plants (23%-48%). These results indicate that instream consumers in the Liuxi River rely more on autochthonous production (e.g., periphyton and submerged hydrophytes) than on terrestrially derived allochthonous matter (e.g., terrestrial plants). The pattern of resource utilization by consumers in the mid-upper Liuxi River is consistent with findings from other open subtropical and neotropical rivers and provides evidence for the riverine productivity model. Our study indicates that protecting inherent producers in rivers (e.g., periphyton and submerged hydrophytes) and restoring their associated habitats (e.g., riffles with cobble substrate) are conducive to aquatic ecosystem management.

Fish isotopic niches associated with environmental indicators and human disturbance along a disturbed large subtropical river in China.

Stable isotopes are increasingly used to detect and understand the impacts of environmental changes on riverine ecological properties. The δ13C and δ15N signatures of fish with different feeding habits were measured in a large subtropical river to evaluate how fish isotopic niches respond to environmental gradients and human disturbance. From basal resources to fish consumers, the high values of epilithic periphyton (biofilm) δ13C and suspended particulate organic matter δ15N concurrently determined the niche ranges and space (e.g., convex hull area) of fish communities. Along a longitudinal gradient (except in the industrial zone), the number of fish trophic guilds identified by Bayesian ellipses continuously increased; meanwhile, higher trophic diversity and less redundancy were observed near the lower reaches and estuary. Variance inflation factors were estimated to detect the multicollinearity of 40 environmental variables, 14 of which were selected as indicators. Relative importance (RI) analysis was used to evaluate the explanatory power of these indicators for the spatial variation in isotopic niche metrics; the results showed that riffle habitat area, water nitrate concentration, gravel-cobble substrate, and riparian buffer width were the 4 key environmental indicators (average RI > 12%) that determined the longitudinal pattern of fish isotopic niches. These findings suggested that community-level δ13C signatures are more responsive to changes in habitats (e.g., riffle) and substrates (e.g., gravel-cobble) supporting the productivity of autochthonous diatoms while δ15N signatures respond to water quality altered by nitrogen pollution from manure-fertilized farming and poultry livestock effluent. Furthermore, δ15N may be more robust and interpretable than δ13C as an isotopic indicator of ecosystem change in rivers exposed to multiple or complex anthropogenic stressors.

Uptake mechanism, subcellular distribution, and uptake process of perfluorooctanoic acid and perfluorooctane sulfonic acid by wetland plant Alisma orientale.

Perfluoroalkyl substances (PFASs) are of particular environmental concern due to their environmental persistence and potential toxicity. Phytoremediation may be used to remove PFASs from wastewater. Here we investigated the uptake mechanism, subcellular distribution, and uptake process of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate acid (PFOS) in the wetland plant Alisma orientale by using a series of hydroponic experiments. Active uptake facilitated by water transporters and anion channels was involved in the uptake of PFASs by plant roots. PFOA and PFOS were mainly distributed in the water-soluble fraction (46.2-70.8%) and in cell walls (45.6-58.4%), respectively. The uptake process was proposed as follows: PFOS and PFOA were first distributed in the soluble fraction; a proportion of PFOS and PFOA were adsorbed gradually by the cell wall, and a proportion of PFOS and PFOA in the cell wall passed through the cell wall and plasmalemma and bind with organelles. PFOS and PFOA were transported from the external solution to the vascular bundle of the plant root through both symplastic and apoplastic routes.

Contamination profiles and health risks of PFASs in groundwater of the Maozhou River basin.

Per-and polyfluoroalkyl substances (PFASs) are a group of chemicals with a wide range of industrial and commercial applications, but little is known about the contamination of PFASs in groundwater and their linkage to surface water. Here we investigated the occurrence of PFASs in groundwater and surface water at the Maozhou River basin in order to understand their contamination profiles and potential health risks. The results showed that total PFASs concentrations ranged from 9.9 to 592.2 ng/L, 50.2-339.9 ng/L and 3.7-74.3 ng/g in groundwater, river water and sediment, respectively. The detection frequencies of C4-C8 chains (C4-C8) PFASs were higher than C9-C14 chains PFASs in the river and groundwater. Statistical analysis showed an obvious correlation between the major contaminants in the river and those in the groundwater, indicating the potential linkage of PFASs in the groundwater to the surface water. The wastewater indicator found in groundwater suggested domestic wastewater was only one of the source for the PFASs in the river and groundwater of Maozhou River basin. Moreover, human health risk assessment showed low risks from the PFASs to the residents by drinking groundwater.

Stable isotopes reveal effects of natural drivers and anthropogenic pressures on isotopic niches of invertebrate communities in a large subtropical river of China.

Isotopic niches reflect the basic structure and functioning of river food webs; however, their response to riverine environments remains unclear. We used stable isotope analysis and community-wide metrics to quantify how invertebrate niches vary with environmental changes along a large subtropical river in China. Eight niche metrics, which had higher values in the wet than in the dry season, increased from headwaters to the middle river and decreased sharply near the estuarine industrial zones. The δ13C value of > - 23.8‰, which indicated consumption of epilithic diatoms, separated the invertebrates between the upper and mid-lower reaches. The δ15N values > 9.4‰ identified site-specific nitrogen sources from manure (e.g., animal effluent) and domestic sewage in agricultural area. The output of mixing models showed a downstream shift in carbon utilization by invertebrates from autochthonous periphyton and submerged hydrophytes to allochthonous C3 plants. Principle component (PC) and cluster analysis decomposed and grouped 40 environmental variables into 4 PCs that explained 84.5% of the total variance. Hierarchical partitioning revealed that the second and first PCs, which were driven mainly by biological indicators and habitat characteristics, had the highest explanatory power for niche ranges and areas (e.g., Bayesian ellipse), respectively. Our results suggest that reducing anthropogenic pressures (e.g., habitat loss and water pollution) on river ecosystems through measures, such as protecting diatom-dominated biofilms in riffles and controlling nitrogen loading in rural regions, may produce the greatest impact for river management. Graphical abstract.

New insight into the toxic effects of chloramphenicol and roxithromycin to algae using FTIR spectroscopy.

Antibiotics have been frequently detected in the aquatic environment, and they may affect aquatic organisms such as algae. Here we investigated toxicity of chloramphenicol (CAP) and roxithromycin (ROX) on four species of green algae (Pseudokirchneriella subcapitata, Scenedesmus quadricauda, Scenedesmus obliquus, and Scenedesmus acuminatus) at biochemical level by Fourier transform infrared spectroscopy (FTIR). The results revealed that both CAP and ROX had negative effects on algal growth and caused alterations of biochemical components. The toxic effects varied among the four algal species and S. acuminatus was found to be less sensitive than the other three species to the antibiotics. Even with similar mechanism of action, ROX displayed more adverse effects to algae than CAP. Both antibiotics could affect algae by inhibiting fatty acid synthesis and promoting protein and DNA aggregation, thus leading to accumulation of lipid peroxidation products, increment of the loose ß-sheet structure protein and transformation of B-DNA to Z-DNA. The findings from this study revealed the toxic mechanism of antibiotics to algae at the biochemical level.

[Concentration-dependent Accumulation and Translocation of PFASs by Wetland Plant Alisma orientale].

This study investigated the concentration-dependent accumulation and translocation of perfluoroalkyl substances (PFASs) by wetland plant Alisma orientale. The concentrations of PFASs in nutrient solution were 0, 5, 10, 50, 100, 200, 500, and 1000 µg·L-1. The electrolytic leakage of roots, Cu concentration in roots and stems, and Ca concentration in stems and leaves decreased with an increase in PFASs concentration in external solution, while the plants were growing well. The removal mass of PFASs by plants increased (0.87-116.50 µg) with an increase in PFASs concentration, while the removal efficiency decreased (20.1%-2.9%). The PFASs concentration in plant roots, stems, and leaves increased linearly with that in nutrient solution, and fitted the Langmuir adsorption isotherm and Michaelis-Menten equation well, which indicated PFASs were uptaken through passive diffusion. The root concentration factor, stem concentration factor, transpiration stream concentration factor, and partition limited quasi-equilibrium factor αpt decreased with that of PFASs in nutrient solution, probably due to the increase in the volume of transpiration water and the longer time to reach equilibrium.