How topography and neighbor shape the fate of trees in subtropical forest restoration:Environmental filtering and resource competition drive natural regeneration

The structure of plant communities at local scales depends on both the spatial heterogeneity of abiotic environmental factors and the biotic interactions within the community.However,although environmental filtering due to microtopographic heterogeneity and resource competition among plants caused by spatial variation in tree density and size are considered to be very important in explaining the mechanisms of community assembly,their effects on the processes of individual mortality and recruitment in natural forest regeneration,as well as their relative contributions,are still poorly understood.To address this,we established a 12-ha permanent plot in a subtropical evergreen broad-leaved forest area and measured microtopographic variables such as elevation,slope,aspect,and terrain position index(TPI)using a total station.We monitored the individual mortality and recruitment in forest natural regeneration through repeated surveys at 5-year intervals.We fitted spatial covariance models to jointly use multiple factors from three groups of variables(microtopographic effect,neighborhood density effects,neighborhood size effects)as explanatory variables to analyze their roles in driving the mortality and recruitment of all individual and 12 dominant species in forest natural regeneration at the neighborhood scale.Our results show that:(1)In the crucial early stages of secondary forest restoration,natural regeneration is influenced by a synergy of environmental filtering,due to microtopographic heterogeneity,and resource competition among plants.(2)For distinct species responses,evergreen dominant species'mortality is largely explained by neighborhood effects,while deciduous species are more affected by topographic factors.Furthermore,the adverse effects of larger conspecific trees on younger trees indicate a pattern of competitive pressure leading to mortality among regenerating trees,such pattern emphasis the influence of parent trees on natural regeneration.(3)As trees grow,their interaction with these stressors evolves,suggesting a shift in their resource acquisition strategies and response to neighborhood effects and environmental factors.Despite these changes,the relative importance of topographic factors in determining survival and recruitment success remains constant.This research highlights the importance of considering both environmental and neighborhood effects in forest management,particularly in early secondary forest restoration.

Dynamic scaling characteristics of single-phase natural circulation based on different strain transformations

To understand the dynamical system scaling(DSS)analysis theory,the applicability of DSSβ-andω-strain transformation methods for the scaling analysis of complex loops was explored.A simplified model consisting of two loops was established based on the primary and secondary sides of a nuclear reactor,andβ-andω-strain transformation methods were used to ana-lyze the single-phase natural circulation in the primary circuit.For comparison with the traditional method,simplified DSSβ-andω-strain methods were developed based on the standard scaling criterion.The strain parameters in these four methods were modified to form multiple groups of scaled-down cases.The transient process of the natural circulation was simulated using the Relap5 code,and the variation in the dynamic flow characteristics with the strain numbers was obtained using different scaling methods.The results show that both the simplified and standard DSS methods can simulate the dynamic characteristics of natural circulation in the primary circuit.The scaled-down cases in the simplified method exhibit the same geometric scaling and correspond to small core power ratios.By contrast,different scaled-down cases in the standard DSS method correspond to different geometric scaling criteria and require more power.The dynamic process of natural circula-tion can be simulated more accurately using the standard DSS method.

Anthropogenic footprints are invading global habitats of Indo-Pacific humpback dolphins

As ecologically fragile areas,coastal zones are affected by both anthropogenic activities and climate change.However,the impacts of these factors on large nearshore mammals,such as Indo-Pacific humpback dolphins(IPHDs,Sousa chinensis),are poorly understood.Here,modeling revealed that the suitable habitats of IPHDs are affected mainly by the sea surface temperature(SST),and the habitat suitability decreases as the distance to the nearest coastline increases.In addition,anthropogenic activities involving demersal fishing,contamination and shipping have narrowed IPHD habitats and reduced the habitat suitability.We found that climate change will further narrow suitable habitats located farther than 7 km from coastlines and trigger habitat losses in the eastern Taiwan Strait by 2090-2100 under the Representative Concentration Pathway(RCP)8.5 scenario.The projected decreases in habitat suitability and area emphasize the urgency of establishing connected marine protected areas(MPAs)while considering climate change,intergovernmental cooperation,and public involvement.

Forms of phosphorus and silicon in the natural grain size surface sediments of the southern Bohai Sea

The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37 μmol/g to 1.57 μmol/g, accounting for 10.7% of the total phosphorus, others were the carbonate bound form, iron manganese oxide bound form and ion exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon’s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55 μmol/g to 8.94 μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12% of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.

Studies on the regional feature of organic carbon in sediments off the Huanghe River Estuary waters

Organic carbon (OC) in definitely small area sediments(according to marine dimension)off the Huanghe River Estuary is investigated in order to evaluate the feature of regional difference of physical and chemical properties in marginal sea sediments.The distributions of OC in sediments with natural grain size and the relationship with the pH,Eh ,Es and Fe3+/Fe2+ are discussed.In addition,OC decomposition rates in surfacial/subsurfacial sediments are estimated.OC concentrations range from 0.26% to 1.8%(wt)in the study area. Significant differences in OC content and in horizontal distribution as well as various trends in surfacial /subsurfacial sediments exhibit the feature of regional difference remarkably in marginal sea sediments. The complicated distribution of OC in surface sediments is due to the influence of bacterial activity and abundance, bioturbation of benthos and physical disturbance. The OC decomposition rate constant in surfacial /subsurfacial sediments ranges from 0.009 7 to 0.076 a-1 and the relatively high values may be mainly related to bacteria that are mainly responsible for OC mineralization;meio-and macrofauna affect OC degradation both directly, through feeding on it, and indirectly through bioturbation and at the same time coarse sediments are also disadvantageous to OC preservation.In almost all the middle and bottom sediments the contents of OC decrease with the increase of deposition depth, which indicates that mineralization of OC in the middle and bottom sediments has occurred via processes like SO reduction and Fe-oxide reduction.

Comparative transcriptomic analysis of Macro brachium nippon ense in response to Aerom onas veronii or Staphylococcus au reus infection

Macrobrachium nipponense is an economically important freshwater prawn that is often threatened by many aquatic pathogens.In this study,comparative transcriptomic analysis was fi rstly used to explore the transcriptional response of M.nipponense to Aeromonas veronii or Staphylococcus aureus stimulation.A total of 400.19 million clean reads were obtained and assembled into 56944 unigenes with an average length of 1253 bp.A total of 1857 diff erentially expressed genes were found after A.veronii infection,including 677 genes that were up-regulated and 1180 genes that were down-regulated,while 1061 signifi cant diff erentially expressed genes were identifi ed after S.aureus infection,including 390 up-regulated and 671 down-regulated genes.Many immune-related genes including Spaetzle,prophenoloxidase activating factor,C-type lectin,anti-lipopolysaccharide factor,and inhibitor of apoptosis 2 protein were commonly up-regulated after A.veronii or S.aureus infection.This study will enrich our understanding of the immune response to gram-positive and gram-negative bacteria infection in crustaceans.

Non-Smooth Bifurcation and Chaos in a DC-DC Buck Converter

A direct-current-direct-current （DC-DC） buck converter with integrated load current feedback is studied with three kinds of Poincaré maps. The external corner-collision bifurcation occurs when the crossing number per period varies, and the internal corner-collision bifurcations occur along with period-doubling and period-tripling bifurcations in this model. The multi-band chaos roots in external corner-collision bifurcation and often grows into 1-band chaos. A new kind of chaotic sliding orbits, which is more complex for non-smooth systems, is also found in this model.

Neighborhood diversity structure and neighborhood species richness effects differ across life stages in a subtropical natural secondary forest

Natural secondary forest has a strong capacity to regrow naturally and recover biodiversity rapidly on abandoned lands.However,at the neighborhood scale,which can truly reflect the facilitative or competitive interactions among individual plants,the local diversity spatial structure in secondary forest and the feedback effects of neighborhood diversity on natural regeneration remain unclear,and this may be the key to properly understand the mechanisms of natural secondary forest species diversity recovery.To this end,this study established a dynamic plot in a rehabilitated secondary forest after disturbance and conducted a comprehensive survey of 68,336 individual plants with repeated measurements at 5-year interval to assess the characteristics of neighborhood diversity structure across life history stages and link the neighborhood species richness(NSR)effect translated by species interactions at species diversity structure with individual trees recruitment/mortality in secondary forest regeneration.The results showed that,compared with tropical and temperate natural forests,a higher proportion of diversity accumulators and a lower proportion of repellers in subtropical secondary forests resulted in neighborhood diversity structures characterized by heterospecific or high-diversity patches,which are beneficial to the maintenance or restoration of biodiversity.As an important supplement to the research on the relationship between diversity and productivity,our findings show a positive diversity-survival relationship in subtropical secondary forests.Importantly,we observed that the neighborhood diversity structure exhibited a trend of accumulator-dominated to neutral-dominant changes with life stage from sapling to adult,which,in turn,determined the direction and strength of NSR effects on recruitment/mortality.Specifically,diverse local neighborhoods at a later successional stage characterized with‘neutral’species-species interactions can act as a‘welfare net’by offering favorable microhabitats for the most vulnerable recruitments or saplings,i.e.,the NSR effects that promoted individual recruitment/survival in our study.These results not only enrich our understanding of the biodiversity-productivity-survival relationship but also highlight the importance of retaining latesuccessional species of native trees in intensive forest production or in situ conservation policies.

Temporal-spatial Change Rules of Mangrove in Guangdong Province and Suggestions on Its Protection Measures

Mangrove ecosystem has an important ecological function. But since it is distributed in land-sea alternating region,mangrove is vulnerable to environmental pollution. Mangrove area of Guangdong Province greatly decreased after the 1950 s,and it declined to the minimum in the1990 s and then gradually increased. Mangrove area of Guangdong Province quickly increased from 2001 to now,and its area in 2014 was 19 824. 53 hm^2,in which Zhanjiang accounted for 72%. During 2001-2014,mangrove area of Guangdong Province increased significantly,in which the newly increased mangrove area in Zhanjiang,Yangjiang,Jiangmen,Zhuhai,Guangzhou and Shantou was larger,with obvious increase magnitude; mangrove area in east Guangdong during 2001-2005 increased quickly,while increase magnitude of mangrove area in west Guangdong and the Pearl River Delta was improved significantly after 2005. Additionally,mangrove species in Guangdong Province continuously decreased from south to north,showing as west Guangdong > the Pearl River Delta > east Guangdong. Mangrove of Guangdong Province could be protected strictly from shoreline control,ecological protection,function upgrading,and ecological restoration.

EFFECT OF ZINC,SELENIUM AND MANGANESE ON THE GROWTH OF A MARINE MICROALGA NANNOCHLOROPSIS OCULATA(EUSTIGMATOPHYCEAE)

The effect of trace metals of Zinc （Zn）, Selenium （Se） and Manganese （Mn） on thegrowth of a marine microalga was determined by culturing Nannochloropsis oculata in f/2 medium enrichedwith different concentrations of the metal compounds. The results showed that concentration and type ofthe metal compound affected the growth of Nannochloropsis. ZnCl2 and Na2SeO3, promoted the growth ofNannochloropsis at relatively low concentrations of 15. 3 μmol/L and 57. 8 μmol/L respectively, but inhib-it its growth at higher concentration of 153 μmol/L and about 300 μmol/L. No significant growth promotionwas observed for MnCl2 and MnSO4 although MnCl2 was found to have higher toxic effect than MnSO4.

Two‑parameter dynamical scaling analysis of single‑phase natural circulation in a simple rectangular loop based on dilation transformation

Scaling analysis is widely used to design scaled-down experimental facilities through which the prototype phenomena can be effectively evaluated.As a new method,dynamic system scaling(DSS)must be verified as a rational and applicable method.A DSS method based on dilation transformation was evaluated using single-phase natural circulation in a simple rectangular loop.The scaled-down cases were constructed based on two parameters—length ratio and dilation number—and the corresponding transient processes were simulated using the Relap5 computational code.The results show that this DSS method can simulate the dynamic flow characteristics of scaled-down cases.The transient deviation of the temperature difference and mass flow rate of the scaled cases decrease with increases in the length ratio and dilation number.The distortion of the transient temperature difference is smaller than that of the mass flow;however,the overall deviation is within a reasonable range.

Distribution of per-and polyfluoroalkyl substances in blood,serum,and urine of patients with liver cancer and associations with liver function biomarkers

Studies have shown that per-and polyfluoroalkyl substances(PFASs)may be hepatotoxic in animals or humans.However,data on clinical epidemiology are very limited.In this study,21PFASs were determined in patients with liver diseases,with the highest median concentrations detected in the serum sample(26.7 ng/mL),followed by blood(10.7 ng/mL)and urine(5.02 ng/mL).Higher total PFAS concentrations were found in hepatocellular carcinoma(HCC)patients compared to non-HCC patients,with significant discrepancies in serum and blood samples.Besides,significant correlations were also found among PFAS concentrations and age,gender,body mass index(BMI),and liver function biomarkers levels.For example,PFAS concentrations are significantly higher in males than in females;Several serum PFASs concentrations increase with age and BMI,while the serum perfluorohexane sulfonic acid(PFHxS)concentrations are negatively correlated with age.In addition,multiple regression models adjusted for age,gender and BMI found that increased serum perfluorobutane sulfonic acid(PFBS),perfluoroheptane sulfonic acid(PFHpS)and perfluorohexylphosphonic acid(PFHxPA)conentrations are correlated with elevated alkaline phosphatase(ALP),aspartate aminotransferase(AST),and alpha-fetoprotein(AFP)(p<0.05).Our results provide epidemiological support for the future study on the potential clinical hepatotoxicity of PFAS.

Three-dimensional heterogeneous electro-Fenton system with reduced graphene oxide based particle electrode for Acyclovir removal

New pollutant pharmaceutical and personal care products(PPCPs),especially antiviral drugs,have received increasing attention not only due to their increase in usage after the outbreak of COVID-19 epidemics but also due to their adverse impacts on water ecological environment.Electro-Fenton technology is an effective method to remove PPCPs from water.Novel particle electrodes(MMT/rGO/Fe_(3)O_(4))were synthesized by depositing Fe3O4 nanoparticles on reduced graphene oxide modified montmorillonite and acted as catalysts to promote oxidation performance in a three-dimensional electro-Fenton(3D-EF)system.The electrodes combined the catalytic property of Fe3O4,hydrophilicity of montmorillonite and electrical conductivity of graphene oxides,and applied for the degradation of Acyclovir(ACV)with high efficiency and ease of operation.At optimal condition,the degradation rate of ACV reached 100%within 120 min,and the applicable pH range could be 3 to 11 in the 3D-EF system.The stability and reusability of MMT/rGO/Fe_(3)O_(4)particle electrodes were also studied,the removal rate of ACV remained at 92%after 10 cycles,which was just slightly lower than that of the first cycle.Potential degradation mechanisms were also proposed by methanol quenching tests and FT-ICR-MS.

Dissolved oxygen in aeration-driven piezo-catalytic for antibiotics pollutants removal in water

The misuse of antibiotics and oxygen-lacking in aquaculture causes serious water environmental problems.Herein,a piezoelectic odd-layered MoS_(2)is prepared and applied to piezo-catalytic remove tinidazole(TNZ)and other antibiotic pollutants with aeration as a piezo-driving force.About 89.6%of TNZ can be degraded by MoS_(2)under aeration in the presence of dissolved oxygen with a reaction rate constant of0.15 min^(-1),which is 2.4 times higher than that under N2atmosphere and quiescence conditions.Quenching experiments and electron paramagnetic resonance(EPR)tests identify that singlet oxygen(^(1)O_(2))and superoxide radical(O_(2)^(·-))are dominant reactive oxygen species in MoS_(2)/aeration system.These results demonstrate that MoS2can trigger a piezoelectric effect and produce charge carriers to generate reactive oxygen species with dissolved oxygen(DO)for contaminant degradation with the turbulence and water bubbles rupture driven by aeration.

Corrigendum to Metagenomic insights into the profile of antibiotic resistomes in sediments of aquaculture wastewater treatment system

The authors regret<We found an error in Eq.(2)of J.Environ.Sci.,2022,113,345-355(Ncell was obtained from the calculation of ARGs-OAP software,so it doesn’t affect the subsequent results).Eq.(2)is revised as follows(Yang et al.,2016).

Influence of kaolinite and montmorillonite on benzo[a]pyrene biodegradation by Paracoccus aminovorans HPD-2 and the underlying interface interaction mechanisms

Clay minerals play an important role in biogeochemical cycling.Here,kaolinite and montmorillonite,the two most abundant and widespread clay minerals with typical layered structures,were selected to investigate and compare their effects on the biodegradation of benzo[a]pyrene(BaP)by Paracoccus aminovorans HPD-2 and to investigate the underlying interface mechanisms.Overall,the BaP degradation efficiency was significantly higher 7 d after montmorillonite addition,reaching 68.9%(P<0.05),when compared with that of the control without addition of clay minerals(CK,61.4%);however,the addition of kaolinite significantly reduced the BaP degradation efficiency to 45.8%.This suggests that kaolinite inhibits BaP degradation by inhibiting the growth of strain HPD-2,or its strong hydrophobicity and readily agglomerates in the degradation system,resulting in a decrease in the bio-accessibility of BaP to strain HPD-2.Montmorillonite may buffer some unfavorable factors,and cells may be fixed on the surface of montmorillonite colloidal particles across energy barriers.Furthermore,the adsorption of BaP on montmorillonite may be weakened after swelling,reducing the effect on the bio-accessibility of BaP,thus promoting the biodegradation of BaP by strain HPD-2.The experimental results indicate that differential bacterial growth,BaP bio-accessibility,interface interaction,and the buffering effect may explain the differential effects of the different minerals on polycyclic aromatic hydrocarbon biodegradation.These observations improve our understanding of the mechanisms by which clay minerals,organic pollutants,and degrading bacteria interact during the biodegradation process and provide a theoretical basis for increasing the biodegradation of soil pollutants by native microorganisms under field conditions.

Study on deformation mechanism of Ti-2Al-2.5Zr alloy tube in the flattening test

The flattening test,using one pair paralleled plates to flatten tube structure radially,is generally employed to examine the ductility of tube used in once through steam generator(OTSG).This study focuses on the stress condition and deformation mechanism analysis on the concentrated stress regions of Ti-2 Al-2.5 Zr alloy tube during the flattening test.Firstly,the finite element analysis was performed using the commercial software ABAQUS to determine the stress condition.Secondly,the Electron BackScattered Diffraction(EBSD)was implemented to observe the microstructure evolution of Ti-2 Al-2.5 Zr alloy.Finally,Schmid law was employed to analyze the activated deformation mechanism under condition of the complex stress.It was found that the condition of the complex stress in stress concentration regions,including tension and compression regions,can be simplified into two directional stresses condition.In grains whose c-axis is nearly towards TD and ND,the strain is mainly accommodated by prismatic slip,whereas in grains whose c-axis deviates about 45°from ND to TD mainly by basal slip.The{10-12}extensive twin and corresponding parent grain orientation mainly relied on the stress condition.Additionally,the intergranular twin pairs connected at common grain boundaries(GBs)with high strain compatibility were found at low angle GBs,which were activated under a combination of macro stress and strain compatibility effect.

Electro-oxidation of Ni(Ⅱ)-citrate complexes at BDD electrode and simultaneous recovery of metallic nickel by electrodeposition

The simultaneous electro-oxidation of Ni(Ⅱ)-citrate and electrodeposition recovery of nickel metal were attempted in a combined electro-oxidation-electrodeposition reactor with a boron-doped diamond(BDD)anode and a polished titanium cathode.Effects of initial nickel citrate concentration,current density,initial p H,electrode spacing,electrolyte type,and initial electrolyte dosage on electrochemical performance were examined.The efficiencies of Ni(Ⅱ)-citrate removal and nickel metal recovery were determined to be 100%and over 72%,respectively,under the optimized conditions(10 m A/cm^(2),pH 4.09,80 mmol/L Na_(2)SO_(4),initial Ni(Ⅱ)-citrate concentration of 75 mg/L,electrode spacing of 1 cm,and 180 min of electrolysis).Energy consumption increased with increased current density,and the energy consumption was 0.032 kWh/L at a current density of 10 m A/cm^(2)(pH 6.58).The deposits at the cathode were characterized by scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).These characterization results indicated that the purity of metallic nickel in cathodic deposition was over 95%.The electrochemical system exhibited a prospective approach to oxidize metal complexes and recover metallic nickel.

Metagenomic insights into the profile of antibiotic resistomes in sediments of aquaculture wastewater treatment system

To meet the rapidly growing global demand for aquaculture products,large amounts of antibiotics were used in aquaculture,which might accelerate the evolution of antibiotic-resistant bacteria(ARB)and the propagation of antibiotic genes(ARGs).In our research,we revealed the ARGs profiles,their co-occurrence with mobile genetic elements(MGEs),and potential hosts in sediments of a crab pond wastewater purification system based on metagenomic analysis.The residual antibiotic seems to increase the propagation of ARGs in the crab pond,but there was no clear relationship between a given antibiotic type and the corresponding resistance genes.The effect of aquaculture on sediment was not as profound as that of other anthropogentic activities,but increased the relative abundance of sulfon-amide resistance gene.A higher abundance of MGEs,especially plasmid,increased the po-tential ARGs dissemination risk in crab and purification ponds.Multidrug and sulfonamide resistance genes had greater potential to transfer because they were more frequently carried by MGEs.The horizontal gene transfer was likely to occur among a variety of microorgan-isms,and various ARGs hosts including Pseudomonas,Acinetobacter,Escherichia,and Klebsiella were identified.Bacterial community influenced the composition of ARG hosts,and Pro-teobacteria was the predominant hosts.Overall,our study provides novel insights into the environmental risk of ARGs in sediments of aquaculture wastewater treatment system.

Degradation of a persistent organic pollutant perfluorooctane sulphonate with Ti/SnO2eSb2O5/PbO2-PTFE anode

PbO2-poly tetra fluoro ethylene(PTFE)coating anode was prepared through electrodeposition method,which involved the use of scanning electron microscope,linear sweep voltammetry,contact angle,and accelerated life test.Degradation of perfluorooctane sulfonate(PFOS)with Ti/PbO2 and Ti/SnO2eSb2O5/PbO2-PTFE anodes was performed.Operating parameters,including initial concentration of PFOS,current density,and initial pH value were evaluated.Experimental results indicated that Ti/SnO2eSb2O5/PbO2-PTFE had longer lifespan(46.5 h)than Ti/PbO2 anode(3.5 h).The hydrophobic property of PbO2 was substantially improved after the addition of PTFE.Hydrophilic Ti/PbO2 with the contact angle of 45.4was transformed into hydrophobic Ti/SnO2eSb2O5/PbO2-PTFE with a contact angle of 130.9.The electrochemical performance was also enhanced after PTFE particles were added into PbO2 electrodeposition coating.The oxygen evolution potential was increased by 0.32 V,and removal ratios of PFOS had increased from 53.5%to 89%after addition of PTFE.When initial PFOS concentration varied from 100 mg/L to 300 mg/L,PFOS removal ratios increased with the initial concentration.High current density favored the high PFOS removal ratio and the defluorination ratio.Low pH profited the degradation of PFOS.However,alkaline atmosphere had detrimental effect to the PFOS desulfonation.Intermediate products of PFOS degradation were identified with liquid chromatography system coupled with a triple-stage quadruple mass spectrometer.Moreover,mechanisms of PFOS degradation were proposed.