Coupled effects of redox-active substances and microbial communities on reactive oxygen species in rhizosphere sediments of submerged macrophytes.

Reactive oxygen species (ROS) play crucial roles in element cycling and pollutant dynamics, but their variations and mechanisms in the rhizosphere of submerged macrophytes are poorly investigated. This study investigated the light-dark cycle fluctuations and periodic variations in ROS, redox-active substances, and microbial communities in the rhizosphere of Vallisneria natans. The results showed sustained production and significant diurnal fluctuations in the O2•- and •OH from 27.6 ± 3.7 to 61.7 ± 3.0 µmol/kg FW and 131.0 ± 6.8 to 195.4 ± 8.7 µmol/kg FW, respectively, which simultaneously fluctuated with the redox-active substances. The ROS contents in the rhizosphere were higher than those observed in non-rhizosphere sediments over the V. natans growth period, exhibiting increasing-decreasing trends. According to the redundancy analysis results, water-soluble phenols, fungi, and bacteria were the main factors influencing ROS production in the rhizosphere, showing contribution rates of 74.0, 17.3, and 4.4 %, respectively. The results of partial least squares path modeling highlighted the coupled effects of redox-active substances and microbial metabolism. Our findings also demonstrated the degradation effect of ROS in rhizosphere sediments of submerged macrophytes. This study provides experimental evidence of ROS-related rhizosphere effects and further insights into submerged macrophytes-based ecological restoration.

Total phosphorus speciation and transport flux dynamics driven by tidal variations in the Shuidong Bay coastal water during summer, China.

Phosphorus (P) is a vital nutrient for the growth of marine organisms. Tidal cycle had major influence on various biogeochemical parameters of the bay and changed nutrients input with the ebb and flow of the tide. Seawater was collected by synchronous continuous observation during summer in 2021, to investigate tide drives total phosphorus (TP) variation on the concentration, speciation and exchange flux between Shuidong Bay (SDB) and South China Sea (SCS). Results indicated that there was significant tidal variation in exchange flux of TP between SDB and SCS. DIP and DOP were the main speciation of TDP in different tidal periods, accounting for 53.9 % and 46.1 %TP flowed from SCS to SDB, and monthly exchange flux was about 21.26 t. This study provides new insights in P tidal cycling across the semi-enclosed bay-coastal water continuum, which was implications for understanding P biogeochemical process and primary production dynamics in coastal water.

Evolution and distribution of antibiotic resistance genes in submerged macrophytes and biofilm systems: From seasonal monitoring to mesocosm experiments.

The aquatic ecosystem has been extensively investigated as a hotspot for the spread of antibiotic resistance genes (ARGs); yet, the evolution and distribution of ARGs profiles in submerged macrophytes biofilms and surrounding water remained unclear. In this study, the dynamic distribution and seasonal variations of microbial communities and ARGs profiles were investigated, alongside their assembly processes and mutual interactions. Bacitracin and multidrug resistance genes were predominant, constituting more than 60% of the total ARGs abundance. The deterministic processes (<65%), influenced by the physicochemical properties of the river environment, governed the assembly and composition of ARGs profiles, exhibiting significant seasonal variation. The peak diversity (21 types) and abundance (0.316 copy ratios) of ARGs were detected during the summer. Proteobacteria and Actinobacteria were the dominant bacterial phyla, accounting for 38.41-85.50% and 4.03-27.09% of the microbial community, respectively. Furthermore, Proteobacteria, especially genera such as Acinetobacter, Burkholderia, and Pseudomonas, with various resistance sequences, were the primary carriers of multiple ARGs. Notably, the genetic exchanges between biofilms and surrounding water facilitated the further propagation of high-risk ARGs, posing greater ecological risks. Redundancy analysis indicated that the total nitrogen and temperature in water determined the fate of pathogenic-resistant species. These findings provided theoretical support for the mitigation of ARGs contamination in aquatic environments.

The coupling effect promotes superoxide radical production in the microalgal-fungal symbiosis systems: Production, mechanisms and implication for Hg(II) reduction.

Redox transformation of mercury (Hg) is critical for Hg exchange at the air-water interface. However, the superoxide radicals (O2•─) contribution of microalgal-fungal symbiotic systems in lake water to Hg(II) reduction is mainly unknown. Here, we studied the enhanced potential for O2•─ production by the coupling effect between microalgae and fungi. The relationships between microenvironment, microorganisms, and O2•─ production were also investigated. Furthermore, the implication of O2•─ for Hg(II) reduction was explored. The results showed that the coupling effect of microalgae and fungi enhanced O2•─ generation in the symbiotic systems, and the O2•─ generation peaked on day 4 in the lake water at 160.51 ± 13.06-173.28 ± 18.21 µmol/kg FW (fresh weight). In addition, O2•- exhibited circadian fluctuations that correlated with changes in dissolved oxygen content and redox potential on the inter-spherical interface of microalgal-fungal consortia. Partial least squares path modeling (PLS-PM) indicates that O2•─ formation was primarily associated with microenvironmental factors and microbial metabolic processes. The experimental results suggest that O2•─ in the microalgal-fungal systems could mediate Hg(II) reduction, promoting Hg conversion and cycling. The findings highlight the importance of microalgae and fungal symbiotic systems in Hg transformation in aquatic environments.

Effects of typhoon events on coastal hydrology, nutrients, and algal bloom dynamics: Insights from continuous observation and machine learning in semi-enclosed Zhanjiang Bay, China.

Typhoons can induce variations in hydrodynamic conditions and biogeochemical processes, potentially escalating the risk of algal bloom occurrences impacting coastal ecosystems. However, the impacts of typhoons on instantaneous changes and the mechanisms behind typhoon-induced algal blooms remain poorly understood. This study utilized high-frequency in situ observation and machine learning model to track the dynamic variations in meteorological, hydrological, physicochemical, and Chlorophyll-a (Chl-a) levels through the complete Typhoon Talim landing in Zhanjiang Bay (ZJB) in July 2023. The results showed that a delayed onset of algal bloom occurring 10 days after typhoon's arrival. Subsequently, as temperatures reached a suitable range, with an ample supply of nutrients and water stability, Chl-a peaked at 121.49 µg L-1 in algal bloom period. Additionally, water temperature and air temperature decreased by 1.61 °C and 2.8 °C during the typhoon, respectively. In addition, wind speed and flow speed increased by 1.34 and 0.015 m s-1 h-1 to peak values, respectively. Moreover, the slow decline of 8.2 % in salinity suggested a substantial freshwater input, leading to an increase in nutrients. For instance, the mean DIN and DIP were 2.2 and 8.5 times higher than those of the pre-typhoon period, resulting in a decrease in DIN/DIP (closer to16) and the alleviation of P limitation. Furthermore, pH and dissolved oxygen (DO) were both low during the typhoon period and then peaked at 8.93 and 19.05 mg L-1 during the algal bloom period, respectively, but subsequently decreased, remaining lower than those of the pre-typhoon period. A preliminary learning machine model was established to predict Chl-a and exhibited good accuracy, with R2 of 0.73. This study revealed the mechanisms of eutrophication status formation and algal blooms occurrence in the coastal waters, providing insights into the effects of typhoon events on tropical coastal biogeochemistry and ecology.

Effects of terrestrial input on heavy metals in Zhanjiang Bay, a typical subtropical bay in the South China Sea.

Understanding the influence of terrestrial inputs on heavy metals in bays is crucial for the environmental protection of regional estuaries and coastal systems. In this study, the concentrations, temporal and regional distribution characteristics, and fluxes of heavy metals (Cr, Cu, Zn, Cd, Pb) in the surface seawater and terrestrial sewage of Zhanjiang Bay (ZJB) in four different seasons were investigated. The results identified the heavy metal concentrations in the sewage outlet around ZJB had significant seasonal variation. The heavy metals in the surface seawater of ZJB had significant spatiotemporal variations. Terrestrial input, biological activity and hydrodynamics affected the overall distribution. The heavy metal emission fluxes indicated that riverine input was the main influencing factor for heavy metals in ZJB (96.22 %). The fluxes of heavy metals into ZJB increased significantly after the typhoon (Cu: 127 %, Zn: 63 %, Pb: 136 %), it was possible to deteriorate the seawater quality.

Characterization and seasonal variation in biofilms attached to leaves of submerged plant.

The microorganisms and functional predictions of leaf biofilms on submerged plants (Vallisneria natans (Val)) and in water samples (surface water (S) and bottom water (B)) in different seasons were evaluated in this study. S and B groups had 3249 identical operational taxonomic units (OTUs) (50.03%), while the Val group only had 1201 (18.49%) unique OTUs. There was significant overlap between microbial communities of S and B groups in the same season, while Val group showed the greater diversity. The dominant microbial clades were Proteobacteria (18.2-47.3%), Cyanobacteria (3.74-39.3%), Actinobacteria (1.64-29.3%), Bacteroidetes (1.31-21.7%), and Firmicutes (1.10-15.72%). Furthermore, there was a significant relationship between total organic carbon and the distribution of microbial taxa (p = 0.047), and TN may have altered the status of Cyanobacteria by affecting its biological nitrogen fixation capacity and reproductive capacity. The correlation network analysis results showed that the whole system consisted of 249 positive correlations and 111 negative correlations, indicating strong interactions between microbial communities. Functional predictions indicated that microbial functions were related to seasonal variation. These findings would guide the use of submerged plants to improve the diversity and stability of wetland microbial communities.

Photobleaching-induced changes in the optical and photochemical properties of algal organic matter.

Algal organic matter (AOM), a significant source of endogenous dissolved organic matter (DOM) is released in high concentrations during cyanobacterial blooms, along with cyanotoxins. Subsequent photobleaching of AOM is an important phenomenon to investigate. In this study, intracellular organic matter (IOM) and extracellular organic matter (EOM) were extracted from cultured cyanobacteria taken from Taihu Lake in China. The formation of photochemically produced reactive intermediates in different stages of IOM and EOM photobleaching was compared to Suwannee River DOM (SRDOM, reference standard DOM). Results revealed notable differences influenced by the pigment component among IOM, EOM, and SRDOM. The pigment in IOM contributed to a triplet state pool with strong energy-transfer but limited electron-transfer capabilities. Notably, IOM exhibited the highest triplets state quantum yield value in the visible region, suggesting its potential significance in pollutant degradation in deeper water layers. For EOM, one of the pools exhibits photolability and remarkable electron-transfer capability, indicating it as a high-energy triplet state component. Moreover, three cyanotoxins (MC-LR, ACA, and ATX-a) were detected in the extracted AOM, and their photodegradation was monitored during the AOM photobleaching process. This highlights the potential role of AOM as a photosensitizer in the natural self-cleaning mechanisms of water bodies, facilitating the degradation of organic pollutants through photochemical reactions. The findings of this study contribute to understanding the dynamic nature of AOM and its implications in environmental processes.

Purification of aquaculture wastewater by macrophytes and biofilm systems: Efficient removal of trace antibiotics and enrichment of antibiotic resistance genes.

The purification performance of aquaculture wastewater and the risk of antibiotic resistance genes (ARGs) dissemination in wetlands dominated by macrophytes remain unclear. Here, the purification effects of different macrophytes and biofilm systems on real aquaculture wastewater were investigated, as well as the distribution and abundance of ARGs. Compared to the submerged macrophytes, artificial macrophytes exhibited higher removal rates of TOC (58.80 ± 5.04 %), TN (74.50 ± 2.50 %), and TP (77.33 ± 11.66 %), and achieved approximately 79.92 % removal of accumulated trace antibiotics in the surrounding water. Additionally, the biofilm microbial communities on the surface of artificial macrophytes exhibited higher microbial diversity with fewer antibiotic-resistant bacteria (ARB) enrichment from the surrounding water. The absolute abundance of ARGs (sul1, sul2, and intI1) in the mature biofilm to be one to two orders of magnitude higher than that in the water. Although biofilms could decrease ARGs in the surrounding water by enriching ARB, the intricate network structure of biofilms further facilitated the proliferation of ARB and the dissemination of ARGs in water. Network analysis suggested that Proteobacteria and Firmicutes phyla were dominant and potential carriers of ARGs, contributing 69.00 % and 16.70 %, respectively. Our findings highlight that macrophytes and biofilm systems have great performance on aquaculture wastewater purification, but with high risk of ARGs.

Seasonal variation, spatial distribution, and sources of PAHs in surface seawater from Zhanjiang bay influenced by land-based inputs.

This study was carried out for a comprehensive understanding of the concentrations, seasonal variation, spatial distribution, sources, and land-based inputs of polycyclic aromatic hydrocarbons (PAHs) in surface seawater from Zhanjiang Bay (ZJB). Although the PAHs were ubiquitous, their concentrations were relatively low, and significant seasonal trends and spatial distributions were observed. Based on the diagnostic ratios and composition profiles, the PAHs found in this study mainly originated from coal/biomass burning, and petroleum and its combustion played an important role in the wet seasons. Furthermore, the PAHs from land-based inputs had seasonal variations, spatial distributions, sources, and composition profiles similar to those in ZJB seawater. By combining the cases of energy structure, residential and industrial layouts, maritime traffic, and activities related to ports and mariculture, this study concluded that PAHs in ZJB seawater are greatly influenced by land-based inputs, atmospheric deposition and human activities.

Effect of different size microplastic particles on the construction of algal-bacterial biofilms and microbial communities.

Algal-bacterial symbiotic system is a biological purification system that combines sewage treatment with resource utilization and has the dual effects of carbon sequestration and pollution reduction. In this study, an immobilized algal-bacterial biofilm system was constructed for the treatment of natural sewage. Effects of exposure to microplastics (MPs) with different particle diameters (0.065 µm, 0.5 µm and 5 µm) were determined in terms of algal biomass recovery efficiency, the composition of extracellular polymeric substances (EPS) and morphologic characteristics. The impacts of MPs on the bacterial diversity and community structure of biofilms were also examined. The metagenomic analysis of key microorganisms and related metabolism pathways involved in system was further investigated. Results showed that following exposure to 5 µm MP, a maximum algal recovery efficiency of 80% was achieved, with a minimum PSII primary light energy conversion efficiency (Fv/Fm ratio) of 0.513. Furthermore, 5 µm MP caused the highest level of damage to the algal-bacterial biofilm, enhancing the secretion of protein-rich EPS. The biofilm morphology became rough and loose following exposure to 0.5 µm and 5 µm MP. Community diversity and richness were significantly high in biofilms exposed to 5 µm MP. Proteobacteria (15.3-24.1%), Firmicutes (5.0-7.8%) and Actinobacteria (4.2-4.9%) were dominant in all groups, with exposure to 5 µm MP resulting in the highest relative abundance for these species. The addition of MPs promoted the related metabolic functions while inhibited the degradation of harmful substances by algal-bacterial biofilms. The findings have environmental significance for the practical application of algal-bacterial biofilms for sewage treatment, providing novel insights into the potential effects of MPs on immobilized algal-bacterial biofilm systems.

Phosphorus speciation and sedimentary phosphorus release in an urban bay (Dachan Bay, China) impacted by multiple anthropogenic perturbations.

Sedimentary phosphorus (P) release and retention are important in controlling P dynamics in coastal waters. Here, two sediment cores were analysed to understand the P speciation and sedimentary P release characteristics in Dachan Bay, Shenzhen, where was highly influenced by human activity. Total phosphorus (TP) concentrations, 52.3 to 1119 µg g-1, fluctuated greatly with depth. Four P binding forms were fractionated: iron-bound P (FeP), authigenic apatite (CaP), detrital P (De-P), and organic P (OP) with the following order of concentration: Fe-P > OP > De-P > Ca-P. The P pollution index (PPI) revealed the contamination of sediment with P in recent years. Additionally, the potentially mobile P pools and long-term P release in the sediments were estimated, and the results indicated that, sediment was an important potentially mobile P pools in the water column, especially in nearshore areas, which required the attention of management departments.

Seasonal changes driving shifts of aquatic rhizosphere microbial community structure and the functional properties.

Ecological floating beds could enable roots to become suspended and this allowed submerged roots to harbour various types of microbes. But, there was a lack of systematic research on microbial community structure changes and the influencing mechanisms. In this study, the ecological floating beds were constructed using selected plants [Cyperus involucratus Rottboll (Cyp), Thalia dealbata Fraser (Tha) and Iris tectorum Maxim (Iri)] that was compared with a control group [static water (S)]. The results showed that the highest abundance and diversity of root microbial communities were found in autumn, with the dominant taxa being Proteobacteria, Actinobacteriota, Cyanobacteria, Chloroflexi, Firmicutes, Bacteroidota, and Acidobacteriota. The microbial communities of Tha and Cyp groups greatly overlapped, while the Iri and control groups exhibited distinctly diverse communities. The root microbial populations of the same plant also reflected a large change in different seasons. Conversely, photosynthetic autotrophs and specialized anaerobes were more inclined to thrive at higher temperatures and lower DO concentrations and then they gradually became the dominant species. Microbial co-occurrences of the Tha and control groups were complex and showed both cooperation and competition. In addition, TOC was an important environmental factor that shaped the microbial community structures and DO changed the microbial community by affecting the abundance of aerobic and anaerobic bacteria. Microorganisms showed potential for degradation and metabolism of non-food substances with low/no corresponding metabolic pathways.

Response of submerged macrophytes and leaf biofilms to different concentrations of oxytetracycline and sulfadiazine.

Oxytetracycline and sulfadiazine were widely used and they entered the environment through various channels such as domestic sewage, medical wastewater and agricultural wastewater, causing significant ecological risk. To determine the effects of different antibiotic concentrations on submerged macrophytes, Vallisneria natans was exposed to solutions containing different concentrations of oxytetracycline and sulfadiazine (0.1 mg/L、1 mg/L、10 mg/L、50 mg/L). After 20-days exposure, we found that 10 mg/L groups had a significant effect on Vallisneria natans. Under high antibiotic concentrations, the growth of Vallisneria natans was inhibited, chloroplasts were deformed, the chlorophyll content was reduced, and antioxidant enzyme activities, such as superoxide dismutase and glutathione, were increased. There was no significant difference between the control group and groups with low antibiotic concentrations (≤1 mg/L). The N-acyl-l-homoserine lactone concentration tended to increase with increasing antibiotic concentrations. The presence of antibiotics also affected the microbial community structure of biofilms on the submerged macrophytes. For example, the higher the concentration of antibiotics, the higher the proportion of Proteobacteria. These results suggest that high concentrations of oxytetracycline and sulfadiazine can disrupt homeostasis, induce effective Vallisneria natans defense mechanisms and alter biofilms in aquatic ecosystems.

The binding effect and photooxidation on oxytetracycline with algal extracellular polymeric substances and natural organic matter.

Surface water contains a large amount of dissolved organic matter (DOM). Interactions between DOM and micropollutants have a significant impact on micropollutant degradation. In this study, algal extracellular polymeric substances (EPS) and natural organic matter (NOM) were selected as two DOM sources and oxytetracycline (OTC) as a representative micropollutant. EPS was mainly composed of tryptophan and protein-like organics, while NOM was mainly composed of fulvic acid-like, humic acid-like, and hydrophobic acid components. In addition, OTC degradation significantly decreased when bound with EPS and the C=O and C-H bonds of CH2 or CH3 groups may be involved in binding EPS and OTC, respectively, while -COOH may be involved in the binding of NOM and OTC. Furthermore, triplet intermediates were found to play a major role in OTC photodegradation in both EPS and NOM, with the contribution calculated as 49.96% and 44.61%, respectively. Steady-state concentrations of 3EPS* in EPS and 3NOM* in NOM were 3.59 × 10-14 mol L-1 and 5.54 × 10-15 mol L-1, respectively. These results provide new insights into the degradation of antibiotic-containing wastewater in the natural environment or engineering applications.

Seasonal Distribution, Composition, and Inventory of Plastic Debris on the Yugang Park Beach in Zhanjiang Bay, South China Sea.

Plastic debris contamination in marine environments is a global problem that poses a considerable threat to the sustainability and health of coastal ecosystems. Marine beaches, as the key zones where terrestrial plastic debris reach coastal waters, are faced with the increasing pressures of human activities. In this study, we explored the distribution, composition, and inventory of plastic debris over seasonal and tidal zones at the Yugang Park Beach (YPB) in Zhanjiang Bay, South China Sea, to provide a baseline for plastic debris on a marine beach. The results showed mean abundance of plastic debris in summer (6.00 ± 2.10 items/m2) was significantly greater than that in winter (3.75 ± 2.12 items/m2). In addition, the composition of plastic debris ranged in size mainly from 1 to 5 mm and 0.5 to 2.5 cm in winter and summer, respectively. In terms of composition, white plastic debris was the most common (81.1%), and foam was the most abundant (64.4%). Moreover, there was a significant relationship between the abundance of plastic debris and sand grain size fraction (p < 0.05), implying the abundances of microplastic debris were more easily impacted by sand grain size (>2 mm). In total inventory, there were about 1.18 × 105 and 2.95 × 105 items of plastic debris on the YPB in winter and summer, respectively. The tidal variation and human activities are responsible for the plastic debris accumulation. This study provided a method to quantify the inventory of plastic debris on a beach and could be helpful to consider regional tidal variations and critical source areas for effective plastic debris clean-up.

Spatiotemporal Variation and Influencing Factors of TSP and Anions in Coastal Atmosphere of Zhanjiang City, China.

Water-soluble anions and suspended fine particles have negative impacts on ecosystems and human health, which is a current research hotspot. In this study, coastal suburb, coastal urban area, coastal tourist area, and coastal industrial area were explored to study the spatiotemporal variation and influencing factors of water-soluble anions and total suspended particles (TSP) in Zhanjiang atmosphere. In addition, on-site monitoring, laboratory testing, and analysis were used to identify the difference of each pollutant component at the sampling stations. The results showed that the average concentrations of Cl-, NO3-, SO42-, PO43-, and TSP were 29.8 µg/m3, 19.6 µg/m3, 45.6 µg/m3, 13.5 µg/m3, and 0.28 mg/m3, respectively. The concentration of Cl-, NO3-, PO43-, and atmospheric TSP were the highest in coastal urban area, while the concentration of SO42- was the highest in coastal industrial area. Moreover, there were significantly seasonal differences in the concentration of various pollutants (p < 0.05). Cl- and SO42- were high in summer, and NO3- and TSP were high in winter. Cl-, SO42-, PO43-, and TSP had significant correlations with meteorological elements (temperature, relative humidity, atmospheric pressure, and wind speed). Besides, the results showed the areas with the most serious air pollution were coastal urban area and coastal industrial area. Moreover, the exhaust emissions from vehicles, urban enterprise emissions, and seawater evaporation were responsible for the serious air pollution in coastal urban area. It provided baseline information for the coastal atmospheric environment quality in Zhanjiang coastal city, which was critical to the mitigation strategies for the emission sources of air pollutants in the future.

Transcriptomic analysis reveals phytohormone and photosynthetic molecular mechanisms of a submerged macrophyte in response to microcystin-LR stress.

Cyanobacterial blooms impose a substantial risk for submerged macrophytes in aquatic environments. This study investigated the cellular and transcriptomic responses of Vallisneria natans to microcystin-LR (MCLR) exposure, as well as abscisic acid (ABA) and strigolactone (SL), which are the major compounds in signaling networks that regulate plant defense. The results revealed that MCLR significantly (p <0.05) decreased the photosynthetic pigments and significantly (p < 0.05) increased the contents of the ABA and SL stress-related phytohormones under MCLR stress. Related genes involved in the photosynthetic pathways were down-regulated, including psbO, psbP, psbQ and psbR. In the SL biosynthetic pathway of roots under MCLR stress, related genes, such as D27 and CCD7, were down-regulated, while the CCD8 and MAX1 genes were up-regulated. In the ABA synthetic pathway, the genes LUT5, ZEP, NCED, ABA2 and AAO3 were up-regulated. Furthermore, a reduction in the content of SL enriched ABA after 3 days under MCLR stress. The potential molecular mechanism of the interactions between SL and ABA were confirmed with the relative up- and down-regulated genes in the pathway, and ABA could play a major role in plant physiology under MCLR stress. This study provides valuable information to understand the stress-related mechanisms of response of submerged macrophytes to cyanobacterial blooms.

Effects of microplastics of different sizes on the Chlorella vulgaris - Ganoderma lucidum co-pellets formation processes.

The effects of different sized MPs on the formation process of algal-fungal co-pellets were studied. The results show that a maximum biomass recovery of 70.96% and a minimum Fv/Fm ratio of 0.463 reached with 5.000 µm-microplastics. Chlorella vulgaris cells and microplastics adhered evenly to the mycelia of Ganoderma lucidum. The contact angle decreased 24.02% and 34.68% with addition of 0.065 µm and 0.500 µm microplastics, respectively, compared to the control group, while the lowest crystallinity index (7.05%) was obtained with 0.065 µm-microplastics addition. Moreover, 5.000 µm microplastics promoted the extracellular polymeric substances (EPS) secretion, with the soluble polysaccharide content increasing by 40.50% and the soluble protein content increasing by 23.25% compared with the single algal-fungal system, while bound polysaccharides increased by 113.26% and bound proteins increased by 29.48%. The 5.000 µm microplastics also significantly promoted enzyme activity in the co-pellets. These results provide a theoretical basis for algal recovery in microplastic-containing water.

Neuroanatomical changes associated with conduct disorder in boys: influence of childhood maltreatment.

Childhood maltreatment (CM) poses a serious risk to the physical, emotional and psychological well-being of children, and can advance the development of maladaptive behaviors, including conduct disorder (CD). CD involves repetitive, persistent violations of others' basic rights and societal norms. Little is known about whether and how CM influences the neural mechanisms underlying CD, and CD-characteristic neuroanatomical changes have not yet been defined in a structural magnetic resonance imaging (sMRI) study. Here, we used voxel-based morphometry (VBM) and surface-based morphometry (SBM) to investigate the influence of the CD diagnosis and CM on the brain in 96 boys diagnosed with CD (62 with CM) and 86 typically developing (TD) boys (46 with CM). The participants were 12-17 years of age. Compared to the CM- CD group, the CM+ CD group had structural gray matter (GM) alterations in the fronto-limbic regions, including the left amygdala, right posterior cingulate cortex (PCC), right putamen, right dorsolateral prefrontal cortex (dlPFC) and right anterior cingulate cortex (ACC). We also found boys with CD exhibited increased GM volume in bilateral dorsomedial prefrontal cortex (dmPFC), as well as decreased GM volume and decreased gyrification in the left superior temporal gyrus (STG) relative to TD boys. Regional GM volume correlated with aggression and conduct problem severity in the CD group, suggesting that the GM changes may contribute to increased aggression and conduct problems in boys with CD who have suffered CM. In conclusion, these results demonstrate previously unreported CM-associated distinct brain structural changes among CD-diagnosed boys.