Investigation on Fe,Mn,Zn,Cu,Pb and Cd fractions in the natural surface coating samples and surficial sediments in the Songhua River,China

Natural surface coating samples （NSCSs） from the surface of shingles and surficial sediments （SSs） in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals （Fe, Mn, Zn, Cu, Pb, and Cd） using the modified sequential extraction procedure （MSEP）. The results show that the differences between NSCSs and SSs in Fe fi＇actions were insignificant and Fe was dominantly present as residual phase （76.22% for NSCSs and 80.88% for SSs） and Fe-oxides phase （20.33% for NSCSs and 16.15% for SSs）. Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase （48.27%） and that in SSs present as residual phase （45.44%）. Zn, Cu, Pb and Cd were found dominantly in residual fractions （〉48%）, and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter （OM）, and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.

Effect of Interaction of Non-residual Fractions on Adsorption of Atrazine onto Surficial Sediments and Natural Surface Coating Samples

To quantify the effect of the interaction of non-residual fractions[Fe oxides（Fe）, Mn oxide（Mn）, organic materials（OMs）] in the surficial sediments and the natural surface coating samples on the adsorption of atrazine（AT）, an AT multiple regression adsorption model（AT-MRAM） was developed. The AT-MRAM improves upon the previous AT additional adsorption model（AT-AAM） with superior goodness-of-fit test（adjusted R2=ca.1.000）, F-test and t-test（P〈0.01）, and reveals the effect of the interaction among the components in the surficial sediments（SSs） and na- tural surface coatings samples（NSCSs） on the adsorption of AT, which was neglected by the AT-AAM. Meanwhile, the AT-MRAM was also verified through adsorption experiments of AT and the relative deviation between predicted maximum adsorption of AT and the experimental one is less than 15%. The resulted information shows that Mn is prone to interact with other non-residual components, the total maximum adsorption of AT is inversly proportional to the level of Mn, and Fe and OMs facilitate the adsorption of AT. The results also indicate that the adsorption of AT is not only dominated by Fe, OMs, Fe/OMs, but also restrained by Fe/Mn, Fe/Mn/OMs, with lesser roles attributed to Mn, and the estimated AT distributions among the components do not agree with that previously predicted by the AT-AAM, especially with the relative contribution of Mn to the adsorption of AT, revealing significant contribution of the interactions among non-residual components in controlling the behavior of AT in aquatic environments.

Measurement of Atrazine Adsorption onto Surficial Sediments(Natural Surface Coatings)——New Evidence for the Importance of Fe Oxides

To reveal the relative contribution of the components, Fe, Mn oxides or organic materials（OMs） in the surficial sediments（SSs）, and the natural surface coating samples（NSCSs） to adsorbing atrazine（AT）, a selective chemical extraction technique was employed, to remove the different components, and the adsorption characteristics of AT on the SSs and the NSCSs were investigated. The observed adsorptions of AT on the original and extracted SSs and NSCSs were analyzed by nonlinear least squares fitting（NLSF） to estimate the relative contribution of the components. The results showed that the maximum adsorption of AT on the NSCSs was greater than that in the SSs, before and after extraction treatments, implying that the NSCSs were more dominant than the SSs for organic pollutant adsorption. It was also found that the Fe oxides, OMs, and residues in SSs（NSCSs） facilitated the adsorption of AT, but Mn oxides directly or indirectly restrained the interaction of AT with SSs（NSCSs） particles. The contribution of the Fe oxides to AT adsorption was more than that of OMs; the greatest contribution to AT adsorption on a molar basis was from the Fe oxides in the nonresidual fractions, indicating that the Fe oxides played an important role in controlling the environmental behavior of AT in an aquatic environment.

Selective extraction and separation of Fe,Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.

Synergetic and Antagonistic Effects of Cadmium on Adsorption of Atrazine on Surficial Sediments

Co-contamination of atrazine（AT） and cadmium（Cd） on the surficial sediments（SSs） and natural suface coating samples（NSCSs） was investigated via thermodynamic adsorption experiments. The results show that surface coatings have a stronger ability to adsorb AT owing to their higher active components compared with surficial sediments. Synergetic and antagonistic effects of Cd on the adsorption of AT were observed. Cd at a lower concentration（≤4.0 mg/L） in the solid/liquid phase enhanced AT adsorption onto the surficial sediments（surface coatings）, while the adsorption of AT would be inhibited at a Cd concentration of more than 8.0 mg/L： AT coordinates strongly to Cd, and AT-Cd complexes seem to be more strongly adsorbed on sediments than AT alone, and at the adsorption of AT can take place on the sites where Cd has been previously adsorbed and Cd acts as a bridge for the interaction be- tween sediments and AT. With the increase of Cd concentration, the superfluous Cd may hold much more adsorption sites and thus inhibits the adsorption of AT. Meanwhile, the effects of co-existed AT on Cd adsorption on SSs（NSCSs） were insignificant since Cd has a stronger competitive ability to be absorbed on SSs（NSCSs）. The present study could be useful in predicting interactions of the metal ions with herbicides and potentially aid the design of remediation strategies for contaminated sediments and groundwater.

Comparison of Pb and Cd adsorption to the surface coatings and surficial sediments collected in Xianghai Wetland

Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of heavy metals in aquatic environments. Pb and Cd adsorption to the surface coatings and surficial sediments were measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0 for surface coatings; and 0 005 mol/L CaCl 2 solution, 25℃ and pH 6 0 for surficial sediments). The Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings and surficial sediments, and the component analyses of surface coatings and surficial sediments were also carried out. Correlation analyses between the maximum adsorption of Pb and Cd(Г max ) and the components in the surface coatings and surficial sediments suggested that there was a statistically significant trend for Pb and Cd adsorption(Г max ) to the surface coatings to increase with increasing in contents of Fe and Mn oxides in the surface coatings and surficial sediments. And the metal adsorption abilities of surface coatings were much stronger than those of surficial sediments, highlighting that in the same water, i.e. at the same pH and initial metal concentrations, the metals(such as lead and cadmium) in supernatant were feasible to be adsorbed by surface coatings than surficial sediments. The more importance of surface coatings than surficial sediments for adsorbing and cycling of heavy metals in aquatic environments was evidenced.

Effects of Surfactant Adsorption on Surficial Wettability of Nonwoven Fabrics

All types of surfactants (cationic, anionic and nonionic) reported in this paper could enhance the surficial wettability of polypropylene (PP) and polyethylene terephthalate (PET) nonwoven fabrics. However, the effects of cationic and nonionic surfactants were better. The longer the treatment time of surfactants on the nonwoven fabrics, the better the surficial wettability. The surficial rewetting time would no longer change above a certain treatment time. The rewettability of nonwoven fabrics could be evidently improved just when the concentration of surfactants was just above the CMC, except for sodium dodecylbenzene sulfonate (LAS). The finer the fibers and the looser the structures, the better the surficial rewettability of nonwoven fabrics.

Surficial modification enabling planar Al growth toward dendrite-free metal anodes for rechargeable aluminum batteries

Al metal possesses ultrahigh theoretical volumetric capacity of 8,040 m Ah cm^(-3),and gravimetric capacity of 2,980 m Ah g^(-1),and thus is highly attractive for electrochemical energy storage.However,it suffers from several issues,such as the dendrite formation,during Al stripping-deposition cycling,which has been verified to account for the short circuit and limited cyclic performance.Herein,we use a facile and applicable method to in-situ reconstruct the Al anode surface with F-Al-O chemical bonds,which could preferentially induce the planar growth of Al along the interface plane,thus leading to the dendrite-free morphology evolution during the cycling.Benefiting from F-Al-O chemical bonds on the surface of Al anodes,long lifespan of symmetric cells can be realized even under 1 m A cm^(-2)and 1 m Ah cm^(-2).Coupling the F-Al anode with graphite-based cathodes,high-voltage dual-ion Al metal batteries can be achieved with long-term cycle stability up to 1,200 cycles(at 0.5 m A cm^(-2)),surpassing the counterparts using pristine Al metal anode.Furthermore,the effectiveness of this surficial modification strategy is also elucidated with the aid of theoretical calculation.This work provides novel insights on low-cost and facile strategies against the Al dendrite growth in aluminum batteries.

Fuzzy Modeling of Surficial Uranium Prospectivity in British Columbia(Canada)with a Weighted Fuzzy Algebraic Sum Operator

This paper demonstrates knowledge-guided fuzzy logic modeling of regional-scale surficial uranium(U)prospectivity in British Columbia(Canada).The deposits/occurrences of surficial U in this region vary from those in Western Australia and Namibia;thus,requiring innovative and carefully-thought techniques of spatial evidence generation and integration.As novelty,this papers introduces a new weighted fuzzy algebraic sum operator to combine certain spatial evidence layers.The analysis trialed several layers of spatial evidence based on conceptual mineral system model of surficial U in British Columbia(Canada)as well as tested various models of evidence integration.Non-linear weighted functions of(a)spatial closeness to U-enriched felsic igneous rocks was employed as U-source spatial evidence,(b)spatial closeness to paleochannels as fluid pathways spatial evidence,and(c)surface water U content as chemical trap spatial evidence.The best models of prospectivity created by integrating the layers of spatial evidence for U-source,pathways and traps predicted at least 85%of the known surficial U deposits/occurrences in>10%of the study region with the highest prospectivity fuzzy scores.The results of analyses demonstrate that,employing the known deposits/occurrences of surficial U for scrutinizing the spatial evidence layers and the final models of prospectivity can pinpoint the most suitable critical processes and models of data integration to reduce bias in the analysis of mineral prospectivity.

Surficial stability analysis of soil slope under seepage based on a novel failure mode

Normally,the edge effects of surficial landslides are not considered in the infinite slope method for surficial stability analysis of soil slopes.In this study,the limit stress state and discrimination equation of an infinite slope under saturated seepage flow were analyzed based on the Mohr-Coulomb strength criterion.Therefore,a novel failure mode involving three sliding zones(upper tension zone,middle shear sliding zone,and lower compression zone)was proposed.Accordingly,based on the limit equilibrium analysis,a semi-analytical framework considering the edge effect for the surficial stability of a soil slope under downslope seepage was established.Subsequently,the new failure mode was verified via a numerical finite element analysis based on the reduced strength theory with ABAQUS and some simplified methods using SLIDE software.The results obtained by the new failure mode agree well with those obtained by the numerical analysis and traditional simplified methods,and can be efficiently used to assess the surficial stability of soil slopes under rainwater seepage.Finally,an evaluation of the infinite slope method was performed using the semi-analytical method proposed in this study.The results show that the infinite slope tends to be conservative because the edge effect is neglected,particularly when the ratio of surficial slope length to depth is relatively small.

Semi-quantitative design of synergetic surficial/interfacial sites for the semi-continuous oxidation of glycerol

Qualitatively identifying the dominant catalytic site for each step of a semi-continuous reaction and semi-quantitatively correlating such different sites to the catalytic performance is of great significance toward the integration of multiple well-optimized sites on a heterogeneous catalyst.Herein,a series of structurally defined TiO_(x)-based catalysts were synthesized to provide a feasible approach to investigate the aforementioned issues using the semi-continuous oxidation of glycerol as a model reaction.Detailed investigations have verified the simultaneous presence of two kinds of Pt active sites:1)Negatively charged Pt bound to the oxygen vacancies of modified TiO_(x)in the form of Pt^(δ−)-O_(v)-Ti^(3+) sites and 2)metallic Pt(Pt_(0)site)located away from the inter-face.Meanwhile,the proportion of surficial and interfacial sites varies over this series of catalysts.Combined in situ FTIR experiments revealed that the reaction network was well-tuned via a site cooperation mechanism:The surficial Pt_(0)sites dissociatively adsorb the OH group of glycerol with a monodentate bonding geometry and the Pt^(δ−)-O_(v)-Ti^(3+) sites dissociate the C=O bond of the aldehyde group in a bidentate form.Furthermore,CO-FTIR spectroscopy confirmed a correlation between the reaction rate/product selectivity and the fraction of surficial/interfacial sites.A rational proportion of surficial and interfacial sites is key to enabling a high yield of glyceric acid.The most active catalyst with 32%surface sites and 68%interfacial sites exhibited 90.0%glycerol conversion and 68.5%GLYA selectivity.These findings provide a deeper understanding of the structure-activity relationships using qualitative identification and semi-quantitative analysis.

Quantitative relationship between surface sedimentary diatoms and water depth in North-Central Bohai Bay,China

To study the quantitative relationship between surface sedimentary diatoms and water depth,67 surface samples were collected for diatom analysis on eight profiles with water depth variation from the muddy intertidal zone to the shallow sea area in North-Central Bohai Bay,China.The results showed that the distribution of diatoms changed significantly in response to the change in water depth.Furthermore,the quantitative relationship between the distribution of dominant diatom species,their assemblages,and the water depth was established.The water depth optima for seven dominant species such as Cyclotella striata/stylorum,Paralia sulcata,and Coscinodiscus perforatus and the water depth indication range of seven diatom assemblages were obtained in the study area above the water depth(elevation)of-10 m.The quantitative relationship between surface sedimentary diatoms and water depth provides a proxy index for diatom-paleo-water depth reconstruction in the strata in Bohai Bay,China.

Characterization of humic acids extracted from the sediments of the various rivers and lakes in China

The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...

Surface-mediated iron on porous cobalt oxide with high energy state for efficient water oxidation electrocatalysis

Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts.However, its realization in a controllable level remains challenging. Using oxygen evolution reaction(OER) as a model reaction, we report a surface-mediated Fe deposition strategy to electronically tailor surface energy states of porous Co_(3)O_(4)(Fe-pCo_(3)O_(4)) for enhanced activity towards OER. The Fe-pCo_(3)O_(4) exhibits a low overpotential of 280 mV to reach an OER current density of 100 mA cm^(-2), and a fast-kinetic behavior with a low Tafel slop of 58.2 mV dec^(-1), outperforming Co_(3)O_(4)-based OER catalysts recently reported and also the noble IrO_(2). The engineered material retains 100% of its original activity after operating at an overpotential of 350 m V for 100 h. A combination of theoretical calculations and experimental results finds out that the surface doped Fe promotes a high energy state and desired coordination environment in the near surface region, which enables optimized OER intermediates binding and favorably changes the rate-determining step.

Classifying the sedimentary environments of the Xincun Lagoon,Hainan Island,by system cluster and principal component analyses

An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a case study from the Xincun Lagoon,Hainan Island in southern China.For the study,surficial sediment samples were collected,together with hydrodynamic and bathymetric surveys,during August 2013.Numerical simulation was carried out to obtain high-spatial resolution tidal current data.The sediment samples were analyzed to derive mean grain size,sorting coefficient,skewness and kurtosis,together with the sand,silt and clay contents.The modern sedimentary environments were classified using system cluster and principal component analyses.Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud（ESSSM） and slightly silty sand（SSS）,which are distributed in the central lagoon and near-shore shallow water areas,respectively.Mean grain size varies from 0 to 8.0Ф,with an average of 4.6Ф.The silt content is the highest,i.e.,52% on average,with the average contents of sand and clay being 43% and 5%,respectively.There exists a significant correlation between mean size and water depth,suggesting that the surficial sediments become finer with increasing water depth.Cluster analyses reveals two groups of samples.The first group is characterized by mean grain size of more than 5.5Ф,whilst the second group has mean grain size of below 3.5Ф.Further,these groups also have different correlations between mean grain size and the other grain size parameters.In terms of the tidal current,the average values of the root mean square velocity（RMSV） are 7.5 cm/s and 6.9 cm/s on springs and neaps,respectively.For the RMSVs that are higher than 4 cm/s,a significant positive correlation is found between the content of the 63–125 μm fraction and the RMSV,suggesting that the RMSV determines the variability of the very fine sand fraction.Based on system cluster and principal component analyses（PCA）,the modern sedimentary environments are classified into three types according to the grain size parameters,RMSVs and water depth data.The results suggest the importance of grain size parameters and high-spatial resolution hydrodynamic data in differentiating the coastal sedimentary environments.

Anchorage Performance and Interfacial Mechanics Transfer Characteristics of a Composite Anchor Bolt with Different Surface Shape

To solve the deficiency of steel anchor blot in corrosion resistance and flaw of GFRP anchor bolt in fracture resistance, our research group develops a new composite anchor bolt made of steel strands wrapped up with compound fiber resin. To improve the cohesion performance of the composite anchor bolt, pull-out tests of different composite anchor bolts with different groove intervals and depths were made and analyzed. The results show that the pulling resistance of the composite anchor bolt increases with the increase of groove interval and depth, but groove interval and depth have optimal value. Based on elastic mechanics, the cohesion between anchor bolts and anchor bodies and its distribution characteristics caused by axial tension are analyzed and cohesion formula is obtained. By contrast, the experimental result is consistent with the theoretical analysis. Therefore, the surficial change of anchor colts could influence the performance of the composite anchor bolt. The cohesion force and anchorage performance can be improved by changing the surface of anchor bolts. Research results show that the new composite anchor bolt is high-performance material in the civil engineering.