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[Display omitted] [ABSTRACT FROM AUTHOR]

• Severe localized recrystallization occurred as a result of floating grains. • Floating grains own the relatively coarser and sparser precipitation of dispersoids. • The innate reason consists in the decreased dispersoids-forming β′ precipitates. The effects of floating grains on the deformed microstructure of a Mn- and Cr-containing Al-Mg-Si-Cu alloy were first clarified based on a comparative study of the dispersoid precipitation and recrystallization behavior with and without floating grains. The presence of floating grains in the direct-chill casting billets resulted in inhomogeneous and sparse precipitation of the α-Al(Mn,Cr)Si dispersoids after homogenization. In response, the Zener drag force was significantly reduced and severe localized recrystallization occurred in the specimen containing floating grains after hot working. Whereas, the specimen without floating grains, which had dense and fine dispersoids, still had an ideal recovery microstructure after solution soaking. The innate reason consists in the special microscale features of floating grains, which significantly decreased the nucleation rate of the dispersoids-forming β′ precipitates. [ABSTRACT FROM AUTHOR]

• A noticeable dissolution of Mn was observed in adsorption of antimony on MnO 2. • Dissolved amount of Mn depended on antimony adsorption capacity of MnO 2. • Variation of crystalline phases possessed an insignificant effect on Mn release. • Mechanisms of Sb capture and Mn release were unveiled at the atomic scale. Manganese dioxide (MnO 2) exhibits great potential for the uptake of antimony (Sb) from wastewater. Much research has been dedicated to enhancing the capacity of MnO 2 for Sb sequestration. However, the dissolution behavior of Mn has been overlooked, and the underlying relationship between Sb(III) adsorption and Mn dissolution is not clear. In this study, batch experiments evidenced that there was a noticeable dissolution of Mn during the adsorption of Sb(III) on MnO 2. A correlation analysis demonstrated that the amount of Mn dissolved was dependent on the Sb(III) adsorption capacity of MnO 2 , regardless of the crystalline phase of MnO 2. Further experimental and theoretical results (taking α-MnO 2 as an example) unveiled that Mn dissolution involved the following stages. First, Sb(III) adsorbed onto the (3 1 0) crystal plane of α-MnO 2 to form a complex via two Mn-O-Sb bonds, which can be proven by the delicate adsorption configuration and corresponding adsorption energy (E ad) of −4.04 eV. Then, three O atoms from the α-MnO 2 progressively deprived two H atoms from Sb(OH) 3 and one H atom from a water molecule bound to Sb(OH) 3 , respectively. This process was verified by the configuration of the transition state (transition state #3) and the occurrence of electron transfer (i.e., the net charge changed by + 2 e). Finally, the Mn-O bonds of α-MnO 2 were weakened and disrupted, leading to the release of Mn into the aqueous solution. This work advances the fundamental understanding of Sb adsorption onto MnO 2 , which not only promotes a re-evaluation of the utility of MnO 2 for Sb(III) elimination but also provides a theoretical guide for the design of robust MnO 2 -based adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • An efficient AC-SH adsorbent for the selective capture of Ag+ was reported. • Ultrahigh adsorption capacity was attributed to the effective S on the AC-SH surface. • Ag+ transformation pathway was primarily driven by reduction. • AC-SH exhibited strong anti-interference ability in efficient capture of Ag+ from complex wastewater. The selective capture of silver ions (Ag+) from wastewater is promising for simultaneous water purification and resource recovery but remains challenging. In this work, an adsorbent obtained by grafting sulfhydryl (SH) groups onto activated carbon (AC) from discarded cigarette butts and heated at 80 °C (AC-SH-80) was designed for Ag+ removal and exhibited a high capacity (719.2 mg/g) and remarkable selectivity. For the first time, we report that the adsorption performance of AC-SH is directly related to the structure–activity mode of surface S. Two previously unnoticed Ag+ uptake mechanisms were revealed by a quantitative analysis of the amount of adsorbed and reduced Ag+: (i) the sulfhydryl groups converted the majority of Ag+ to Ag; (ii) a minor amount of Ag+ chelated with C–O and C = O due to electrostatic effects. Benefitting from these Ag+ transformation pathways, AC-SH-80 exhibits remarkable selectivity and can realize the efficient removal of Ag+ from actual wastewater with complex backgrounds. This work uncovers the role of S in the Ag+ capture process to provide a new interpretation of the pathways involved in the adsorption of heavy metal ions to functional group-modified materials. [ABSTRACT FROM AUTHOR]

Reports that trace pollutants in the surface water of the Arctic region have been analyzed by the capillary gas chromatography with the micro-electron capture detector (GC-μECD), the gas chromatography-mass spectrometry (GC-MS) and the inductively coupled plasmas-mass spectrometry (ICP-MS). How the ration of α-/γ-HCH indicates the different pesticide composition between these two regions and is the potential marker for the source of the OCPs.

The deep separation between In(III) and Fe(III) ions is considered as an important technological challenge in the engineering fields. The In(III) ions are closer to the soft acid in terms of Lewis acidity due to the smaller polarizability and greater deformability than the Fe(III) ions, which facilitates the possibility of separating them. Herein, the Lewis basicity of the N‐containing adsorption sites is regulated by the fluorine‐containing group to better match with the In(III) ions rather than Fe(III) ions, causing a significant discrepancy in the binding of the adsorption sites to them. Moreover, targeted programmed desorption techniques based on the potential energy differences of the adsorption sites can achieve the deep separation of In(III) and Fe(III) ions, and reach an exceptional concentration of 20.7 mmol L−1 for In(III) ions in the initial desorption solution with extremely high mass ratio (mIn/mFe = 151.7). This work provides a novel technique for in‐depth separation of In(III) and Fe(III) ions from mixed systems, and a new strategy for separating metal ions with similar or close properties. [ABSTRACT FROM AUTHOR]

The Feidong district is located in the southern segment of the Tan–Lu fault zone that separates the South China Block (NCB) from the North China Craton (NCC). We report zircon U‐Pb geochronology and Hf isotope data, as well as whole‐rock geochemistry for Xishanyi granodiorite and Jianshan granite in the Feidong district. Zircon U‐Pb dating results show that the emplacement ages of the Xishanyi and Jianshan intrusions are 124 ± 3 Ma and 130 ± 1 Ma respectively, coeval with magmatic events linked to large‐scale lithospheric thinning in eastern China. The whole‐rock geochemistry of the Xishanyi and Jianshan intrusions demonstrate that they are peraluminous, high potassium calc‐alkaline I‐type granites with adakitic characteristics. Both intrusions underwent weak crustal assimilation during emplacement. The in situ zircon ∊Hf(t) values of the Xishanyi granodiorites range from –26.4 to –21.8, with TDM2 model ages of 2552 to 2841 Ma. The in situ zircon ∊Hf(t) values of the Jianshan granite are from –27.5 to –23.0 with TDM2 model ages of 2632 to 2904 Ma. The peak age of inherited zircon grains from the Xishanyi granodiorite and the Jianshan granite were ∼2.07 Ga and ∼1.94 Ga, respectively. After compared with the regional magmatism, we suggest that both the Xishanyi and Jianshan granitoid intrusions were derived from partial melting of the NCC lower crust. [ABSTRACT FROM AUTHOR]

To study human-induced changes in sedimentation and carbon sequestration over the last 100 years in Dalian Bay (a typical coastal sea in North China), three sediment cores from different locations (C1, C2 and C3) were collected and the chronologies of their depths were evaluated from a radionuclides-based approach. Sedimentation rates (mass accumulation rates) over core depths were calculated based on 210Pb ex chronologies, with maximum values of 8.69 kg m−2·yr−1, 5.65 kg m−2·yr−1 and 8.47 kg m−2·yr−1 for C1, C2 and C3, all appearing at the top layer. Distinct increases in sedimentation rates since the 1980s were observed. Correlations between increasing sedimentation rates and decreasing sea areas of Dalian Bay after 1980 verified the influence of human activities on the sedimentary processes. The range of ratios on total organic carbon to total nitrogen (TOC/TN) and isotopic composition of carbon (δ13C) in the sediment was 9.44–17.9 and −22.81‰ to −24.46‰ respectively. Sedimentary organic carbon (SOC) in Dalian Bay showed characteristics of significant terrestrial input, while also being influenced by marine input. The carbon sequestration potential in Dalian Bay's sediment, based on the sequestration rate of SOC (SR-SOC), showed pronounced increase over time, especially since the 1980s. Primarily driven by sedimentation rate, the carbon sequestration potential was dominated by natural processes before 1980. Since then, it came under significant influence from human activities, and this trend grew more intense after the year 2000. Ecosystem service values from carbon sequestration were assessed, and the values' slower increase was the combined result of Dalian Bay's increased SR-SOC and decreased sea area. • Sediment chronology over depth for the last 100 years in Dalian Bay were investigated. • Sedimentation rate increased after 1980, which correlated with decreased sea area. • SOC presented characteristic of terrestrial input based on TOC/TN ratios and δ13C. • Driven by sedimentation rate, SR-SOC's increase since the 1980s recorded human-induced influence. • Ecosystem service value from carbon sequestration was a combined result of increasing SR-SOC and decreasing sea area. [ABSTRACT FROM AUTHOR]

Dislocation nucleation plays a key role in plastic deformation of diamond crystal. In this paper, homogeneous and heterogeneous nucleation nature for diamond 1 6 112 glide set dislocation and 1 2 110 shuffle set dislocation is studied by combining molecular dynamics method and continuum mechanics models. Our results show that although heterogeneous dislocation nucleation can decrease its activation energy, the activation energy at 0 GPa for diamond heterogeneous nucleation is still in the range of 100 eV. For 1 6 112 glide set and 1 2 110 shuffle set homogeneous nucleation, their critical nucleation shear stress approaches to diamond's ideal shear strength which implies that those dislocations do not nucleate before diamond structural instability only by a purely shearing manner. While for 1 6 112 glide set and 1 2 110 shuffle set heterogeneous nucleation, their critical nucleation shear stresses are 28.9 GPa and 48.2 GPa, these values are less than diamond's ideal shear strength which implies that these dislocations may be nucleated heterogeneously under certain shear stress condition. In addition, our results also indicate there exists a deformation mode transformation for diamond deformation behavior at strain rate of 10 −3 /s. Our results provide a new insight into diamond dislocation nucleation and deformation. [ABSTRACT FROM AUTHOR]

In the present study, the contamination level and spatial distribution of PFASs in the water dissolved phase and suspended particulate matter (SPM) phase of the Dalian Bay, and the SPM-water partition behavior were investigated. The total concentrations of PFASs (∑PFASs) in the water dissolved phase ranged from 6.9 to 17.1 ng L −1 , with perfluorooctanoic acid (PFOA), perfluorobutanoic acid, and perfluorobutane sulfonate (PFBS) as the predominant PFASs, while ∑PFASs in SPM ranged from 1.7 to 27.5 ng g −1 dw with higher contributions from PFBS, perfluorooctane sulfonic acid and PFOA. As for the pollution distribution, the concentrations of PFASs inside the Dalian Bay were higher than those outside the bay. For perfluoroalkyl carboxylic acid (PFCAs) and perfluoroalkane sulfonic acids (PFSAs), the suspended particulate matter-water partition coefficient (log K d ) values ranged from 2.62 to 3.76, and from 3.39 to 3.56, respectively. The log K d values of PFASs generally increased with the increasing perfluorinated carbon chain length. Short-chain PFCAs were mostly detected in the water dissolved phase, while long-chain PFCAs and PFSAs appeared to bind more strongly to SPM phase. The contamination level of long-chain PFCAs and PFSAs could be underestimated if only the water dissolved phase were measured. Therefore, further investigations should consider the role of SPM on the environmental behavior and fate of PFASs in the aquatic environment. [ABSTRACT FROM AUTHOR]

Since bacterial quorum sensing system has been verified to regulate many microbial physiological activities, such as virulence factor production and biofilm formation in pathogens, blocking quorum sensing has being recognized as a viable approach for the development of novel therapeutics in treating bacterial infections. In this study, quorum quenching activities of marine actinomycetes isolated from seawater sample were investigated. Out of 56 morphological different strains, 5 strains had been found exhibiting anti-quorum sensing activity against the violacein production ofChromobacterium violaceum12472. One highly active strain HY026 was identified asStreptomyces parvulusbased on the 16S rDNA sequence analysis and morphological features. Spent culture medium of HY026 could also significantly inhibit the biofilm formation of four bacteria. One major active compound named F1-4, accounting for 26.3% of crude extracts, was obtained from HY026 cultures and identified as actinomycin D based on the analysis of the NMR and MS. F1-4 could significantly inhibit the violacein production ofC. violaceumwith the inhibition rate of 64.9% but not affect the bacterial growth at the concentration of 12.5 µg/mL. F1-4 could also inhibit the prodigiosin production ofSerratia proteamaculans657 with the pigment inhibition zone of 13.5 mm at concentration of 25 µg/disc without affecting the bacterial growth. Another pure compound, cyclic (4-hydroxy-Pro-Phe) was also isolated and identified from this actinomycetes strain. The higher production and easier isolation of actinomycin D fromS. parvulusHY026 indicated that this strain could be a potential source of quorum sensing inhibitors. [ABSTRACT FROM AUTHOR]

Increasing use of chemical dispersants for oil spills highlights the need to understand their adverse effects on marine microalgae and nutrient assimilation because the toxic components of crude oil can be more bioavailable. We employed the crude oil water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) to compare different responses in marine microalgae (Phaeodactylum tricornutum) coupled with stable isotopic signatures. The concentration and proportion of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs), which are key toxic components in crude oil, increased after dispersant addition. CEWAF exposure caused higher percent growth inhibition and a lower chlorophyll- a level of microalgae than those after WAF exposure. Compared with WAF exposure, CEWAF led to an enhancement in the self-defense mechanism of P. tricornutum , accompanied by an increased content of extracellular polymeric substances. 13C-depletion and carbon assimilation were altered in P. tricornutum , suggesting more HMW PAHs could be utilized as carbon sources by microalgae under CEWAF. CEWAF had no significant effects on the isotopic fractionation or assimilation of nitrogen in P. tricornutum. Our study unveiled the impact on the growth, physiological response, and nutrient assimilation of microalgae upon WAF and CEWAF exposures. Our data provide new insights into the ecological effects of dispersant applications for coastal oil spills. [Display omitted] • High proportion of HMW PAHs in CEWAF led to severe adverse effects on microalgae. • Algal cells in CEWAF were more 13C-depleted and 15N-enriched than WAF, respectively. • The light carbon from crude oil can be assimilated by P. tricornutum in CEWAF. • Compared with WAF, the self-defense mechanism of P. tricornutum in CEWAF enhanced. [ABSTRACT FROM AUTHOR]

To enrich knowledge concerning occurrence and behavior of novel brominated flame retardants (NBFRs) in the Chinese marine environment, a group of 11 NBFRs were measured in the atmosphere over the northern Bohai and Yellow Seas. Samples were taken downwind of the primary NBFR production and application areas in North China. The total NBFR air concentrations (ΣNBFRs) varied from 80.9 to 934 pg/m3, with decabromodiphenyl ethane (DBDPE) being the most abundant component. The high spatial variability of ΣNBFRs and relatively weak correlations among individual compounds indicated the diverse impact of anthropogenic activities in the coastal regions. The K OA-based absorption model predicted the distributions of low-mass NBFRs, while a steady state model was more applicable for heavier compounds such as DBDPE. The partitioning of NBFRs between the gas and particle phases were significantly related with octanal–air partition coefficient (K OA) only for the notable pollution locations, suggesting absorptive contribution to NBFR sorption. The resulting relationships characterized by event differences possibly pointed out the influences including the sources of NBFRs and aerosol particles, the continental impact, and the sorption kinetics on NBFR partitioning behaviors. Dry particle-bound deposition estimations indicated that the NBFR inputs to the sea from the air was significant. [Display omitted] • DBDPE dominated air NBFR profiles in consistence with land usage pattern. • Difference in nearby continental outflow underlies NBFR spatiality in marine air. • Sorption of low- and high-mass NBFRs to aerosols differed in sorptive process. • Significant dry particle-bound deposition of NBFRs into sea was observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high-performance gold capture material C-S-180 has been reported. • C-S-180 exhibits excellent gold selectivity in intricate wastewater. • Sulfur modulates the electronic structure of the skeleton to promote gold capture. • C-S optimized energy band gap for a more efficient gold reduction process. The efficient and selective recovery of gold from secondary sources is key to sustainable development. However, the complexity of the recovery environment can significantly complicate the compositions of utilized sorbents. Here, we report a straw-derived mesoporous carbon as an inexpensive support material. This mesoporous carbon is modified by anions (sulfur modulation, C-S-180) to improve its electron-transfer efficiency and tune the electronic structure of its skeleton toward enhanced gold reduction. The high surface area of C-S-180 (989.4 m2/g), as well as the presence of abundant C–S in the porous structure of the adsorbent, resulted in an outstanding Au3+-uptake capacity (3422.75 mg/g), excellent resistance to interference, and favorable Au3+ selectivity. Dissimilar to most existing carbon-based adsorbents, electrochemistry-based studies on the electron-transfer efficiencies of adsorbents reveal that sulfur modulation is crucial to optimizing their adsorption performances. Furthermore, the density functional theory reveals that the optimization mechanism is attributable to the adjustment of the electronic structure of the carbon skeleton by C–S, which optimizes the band-gap energy for enhanced Au3+ reduction. These findings offer a strategy for constructing green and efficient adsorbents, as well as a basis for extending the applications of inexpensive carbon materials in gold recovery from complex environments. [ABSTRACT FROM AUTHOR]

Abstract The concentrations and congener-specific profiles of polybrominated diphenyl ethers (PBDEs) were investigated in the atmosphere, soil and moss samples were collected from Ny–Ålesund, Svalbard in the Arctic and King Georgia Island (KGI), Fildes Peninsula in Antarctica, respectively. The congener profiles of PBDEs were symmetrical between gas and moss, as well as between particles and soil at Ny–Ålesund and KGI, respectively, similar to a "mirror image". The proportions of highly brominated congeners (for example, BDE–99, –153 and –183) in the particle phase and soil were higher than those in the gas phase and moss, while tri– and tetra–BDEs possessed higher proportions in the gas phase and moss at both sites. The slopes of log–log linear correlations between the gas–particle partition coefficient (K p) and sub–cooled liquid vapor pressures (p ° L) of PBDEs were observed at both sites compared with the values in the urban areas. Moreover, the slopes of log K p vs. log p ° L (−0.51 at Ny–Ålesund and − 0.29 at KGI) were notably close to the slopes of log–log linear correlations between the dimensionless soil–moss quotient (Q SM) and p ° L (−0.42 at Ny–Ålesund and −0.22 at KGI). Significant correlations between particle fraction (φ particle) and soil fraction (φ soil) at both sites indicated that the gas–particle partitioning of PBDEs is directly related to their distribution in moss and soil. Graphical abstract Unlabelled Image Highlights • The atmospheric residual level of PBDEs both in Arctic and Antarctic was much lower than that of low latitudes. • The proportions of highly brominated congeners in the particulate and soil were higher than those in the gas and moss. • The PBDE congener profiles were symmetrical between gas and moss, as well as between particles and soil at both sites. • The gas/particle partitioning of PBDEs is directly related to their distribution in moss and soil. [ABSTRACT FROM AUTHOR]

Abstract Sulfonamide antibiotics (SAs) are increasingly detected as aquatic contaminants and exist as different dissociated species depending on the pH of the water. Their removal in sunlit surface waters is governed by photochemical transformation. Here we report a detailed examination of the hydroxyl radical (•OH) and singlet oxygen (1O 2) mediated photooxidation of nine SAs: sulfamethoxazole, sulfisoxazole, sulfamethizole, sulfathiazole, sulfamethazine, sulfamerazine, sulfadiazine, sulfachloropyridazine and sulfadimethoxine. Both •OH and 1O 2 oxidation kinetics varied depending on the dominant protonated states of the SA in question (H 2 SAs+, HSAs0 and SAs−) as a function of pH. Based on competition kinetic experiments and matrix deconvolution calculations, HSAs0 or SAs− (pH ∼5–8) were observed to be more highly reactive towards •OH, while SAs− (pH ∼8) react the fastest with 1O 2 for most of the SAs tested. Using the empirically derived rates of reaction for the speciated forms at different pHs, the environmental half-lives were determined using typical 1O 2 and •OH concentrations observed in the environment. This approach suggests that photochemical 1O 2 oxidation contributes more than •OH oxidation and direct photolysis to the overall phototransformation of SAs in sunlit waters. Based on the identification of key photointermediates using tandem mass spectrometry, 1O 2 oxidation generally occurred at the amino moiety on the molecule, whereas •OH reaction experienced multi-site hydroxylation. Both these reactions preserve the basic parent structure of the compounds and raise concerns that the routes of phototransformation give rise to intermediates with similar antimicrobial potency as the parent SAs. We therefore recommend that these phototransformation pathways are included in risk assessments concerning the presence and fate of SAs in waste and surface waters. Graphical abstract Image 1 Highlights • Aquatic photooxidation of sulfonamides (SAs) via reactive oxygen species is important. • The kinetics depend on pH and separate reactivities of H 2 SAs+, HSAs0 and SAs−. • 1O 2 plays a key role in aquatic fate of SAs compared with •OH and direct photolysis • Different primary pathways and multiple intermediates occur for the three reactions. [ABSTRACT FROM AUTHOR]

Fluoroquinolone antibiotics (FQs) are ubiquitous and ionisable in surface waters. Here we investigate gatifloxacin (GAT) and balofloxacin (BAL), two widely used FQs, and determine the photochemical reactivity of their respective dissociation species that arise at different pH to understand the relevance and pathways of phototransformation reactions. Simulated-sunlight experiments and matrix calculations showed that neutral forms (HFQs 0 ) of the two antibiotics had the highest apparent photolytic efficiency and hydroxyl-radical oxidation reactivity. Based on the pH-dependent photochemical reactivities, the solar apparent photodegradation half-lives ( t 1/2 ) in sunlit surface waters ranged from 14.5–169 min and was 1–2 orders of magnitude faster than hydroxyl-radical induced oxidation ( t 1/2 = 20.9–29.8 h). The corresponding pathways were proposed based on the identification of key intermediates using HPLC-ESI-MS/MS. The apparent photodegradation induced defluorination, decarboxylation, and piperazinyl oxidation and rearrangement, whereas hydroxyl-radical oxidation caused hydroxylated defluorination and piperazinyl hydroxylation. The photomodified toxicity of GAT and BAL was examined using an Escherichia coli activity assay. E . coli activity was not affected by BAL, but was significantly affected by the photo-modified solutions of GAT, indicating that primary photo-degradates have a comparable or higher antibacterial activity than the parent GAT. In fresh water and seawater this antibacterial activity remained high for up to 24 h, even after GAT had undergone significant photodegradation (>1 half-life), indicating the potential impact of this chemical on microbial communities in aquatic systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • POP-BPy exhibits excellent stability in extreme water environments. • Selective capture of palladium from aqua regia was achieved by POP-BPy. • Protonation-armed pyridine nitrogen served as active site for Pd capture. • Almost all of Pd in leachate of spent catalysts was recovered by POP-BPy. Due to the hostile environment in which it is recovered, selective separation of palladium from the leachate of spent catalysts containing palladium is of considerable utility but faces substantial obstacles. This work designed and synthesized a bipyridine-based porous organic polymer (POP-BPy) via free radical polymerization. Meanwhile, its adsorption characteristics and the mechanism of adsorption in extreme environments were examined. In hostile conditions, the resultant POP-BPy display exceptional mechanical stability and environmental resistance. Impressively, POP-BPy has an excellent adsorption capacity of Pd(II) (248 mg/g) in harsh environments (aqua regia: AR; half-diluted aqua regia: AR"1 + 1"), and also had superior selectivity and rapid kinetics. The selectivity of POP-BPy for Pd(II) was verified in combination with relevant experiments (β Pd(II)/Pt(II) = 36.19, β Pd(II)/Pt(II) = 23.90). Furthermore, combining density functional theory (DFT) and molecular dynamics (MD) simulations, the mechanism of selectivity of POP-BPy for Pd(II) was revealed from static adsorption sites to dynamic adsorption processes in a holistic manner, which attributed to the strong attraction of protonated pyridine nitrogen to PdCl 4 2- and site suitability. Furthermore, the application of POP-BPy to spent catalyst recovery resulted in up to 100% removal of Pd(II) from the actual leaching solution, and fixed bed column experiments can effectively treat 2688 bed volumes (L) of feed streams (10 mg/L) before reaching the breakthrough point (<1 mg/L). Overall, this work has opened up new avenues for the selective recycling of valuable metals in harsh environments. [ABSTRACT FROM AUTHOR]

Given the large amount of toxic Cr(VI) wastewater from various industries, it is urgent to take effective treatment measures. Adsorption has been regarded as highly desirable for Cr(VI) removal, but the effectiveness of most adsorbents is significantly dependent on pH value, in which precipitous performance drop and even structural collapse generally occur in strong acidic/alkaline aqueous. Thus, maintaining high adsorption performance and structural integrity over a wide pH range is challenging. To efficiently remove Cr(VI), we designed and prepared of an acid-base resistant metal-organic framework (MOF) Zr-BDPO, by introducing weak acid-base groups (-NH-, -N= and -OH) onto the ligand. Zr-BDPO achieved a maximum adsorption capacity of 555.6 mg · g−1 and retained skeletal structure at pH= 1–11. Interestingly, all these groups can generate conjugate acid-base pairs by means of H+ and OH- in the external solution and then form buffer layer. The removal of Cr(VI) at a broad range of pH values primarily via hydrogen bonds between -NH- and -OH, and the oxoanion species of Cr(VI) is unusual. This strategy that insulating high concentrations of acids and bases and relying on hydrogen bonds to capture Cr(VI) oxoanions provides a new perspective for actual Cr(VI) wastewater treatment. [Display omitted] • A Zr-based metal organic framework with a buffer layer was designed and prepared. • Weak acid-base groups at high or low pH can form conjugate acid-base pairs with itself. • Cr(VI) can be removed over a wide pH range by Zr-BDPO. • The interaction between Zr-BDPO and Cr(VI) was investigated with characterization analysis and DFT calculations. [ABSTRACT FROM AUTHOR]

Hydroxyl polycyclic aromatic hydrocarbons (OH-PAHs) are derived from hydroxylated PAHs as contaminants of emerging concern. They are ubiquitous in the aqueous and atmospheric environments and may exist in the polar snow and ice, which urges new insights into their environmental transformation, especially in ice. In present study the simulated-solar ( λ > 290 nm) photodegradation kinetics, products and pathways of four OH-PAHs (9-Hydroxyfluorene, 2-Hydroxyfluorene, 1-Hydroxypyrene and 9-Hydroxyphenanthrene) in ice were investigated, and the corresponding implications for the polar areas were explored. It was found that the kinetics followed the pseudo-first-order kinetics with the photolysis quantum yields ( Φ s ) ranging from 7.48 × 10 −3 (1-Hydroxypyrene) to 4.16 × 10 −2 (2-Hydroxyfluorene). These 4 OH-PAHs were proposed to undergo photoinduced hydroxylation, resulting in multiple hydroxylated intermediates, particularly for 9-Hydroxyfluorene. Extrapolation of the lab data to the real environment is expected to provide a reasonable estimate of OH-PAH photolytic half-lives ( t 1/2,E ) in mid-summer of the polar areas. The estimated t 1/2,E values ranged from 0.08 h for 1-OHPyr in the Arctic to 54.27 h for 9-OHFl in the Antarctic. In consideration of the lower temperature and less microorganisms in polar areas, the photodegradation can be a key factor in determining the fate of OH-PAHs in sunlit surface snow/ice. To the best of our knowledge, this is the first report on the photodegradation of OH-PAHs in polar areas. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs), a class of ubiquitous pollutants in marine environments, exhibit moderate to high adverse effects on aquatic organisms and humans. However, the lack of PAH toxicity data for aquatic organism has limited evaluation of their ecological risks. In the present study, aquatic predicted no-effect concentrations (PNECs) of 16 priority PAHs were derived based on species sensitivity distribution models, and their probabilistic ecological risks in seawater of Liaodong Bay, Bohai Sea, China, were assessed. A quantitative structure-activity relationship method was adopted to achieve the predicted chronic toxicity data for the PNEC derivation. Good agreement for aquatic PNECs of 8 PAHs based on predicted and experimental chronic toxicity data was observed ( R2 = 0.746), and the calculated PNECs ranged from 0.011 µg/L to 205.3 µg/L. A significant log-linear relationship also existed between the octanol-water partition coefficient and PNECs derived from experimental toxicity data ( R2 = 0.757). A similar order of ecological risks for the 16 PAH species in seawater of Liaodong Bay was found by probabilistic risk quotient and joint probability curve methods. The individual high ecological risk of benzo[ a]pyrene, benzo[ b]fluoranthene, and benz[ a]anthracene needs to be determined. The combined ecological risk of PAHs in seawater of Liaodong Bay calculated by the joint probability curve method was 13.9%, indicating a high risk as a result of co-exposure to PAHs. Environ Toxicol Chem 2016;35:1587-1593. © 2015 SETAC [ABSTRACT FROM AUTHOR]

Concentrations of 16 polybrominated diphenyl ether (PBDE) congeners were measured in river sediments, paddy soils and three species of paddy-field organisms (crab, loach and carp) collected from the Liaohe River Basin, northeastern China. The total contents of PBDEs (∑ 16 PBDEs) in sediments and paddy soils were in the ranges of 273.4–3246.3 pg/g dry weight (dw), and 192.1–1783.8 pg/g dw, respectively. BDE 209 was the dominant congener both in sediments and paddy soils. The concentrations of ∑ 16 PBDEs in sediments were significantly higher than those in the adjacent paddy soils, indicating a potential transport of PBDEs from river to paddy ecosystems via river water irrigation. The biota–soil accumulation factor (BSAF) was calculated as the ratio between the lipid-normalized concentration in paddy-field organisms and the total organic carbon-normalized concentration in paddy soil. The average BSAF values of ∑ 15 PBDEs followed the sequence of crab (3.6) > loach (3.3) > carp (2.1). BDE 154 had the highest BSAF value, and a parabolic trend between BSAF values of individual PBDE congeners and their log K OW values was observed. In view of the fact that crab had the larger BSAF value and higher lipid content, the ecological risk and health risk for crab cultivation in paddy fields should be of particular concern. [ABSTRACT FROM AUTHOR]

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) are contaminants of emerging concern in the aquatic environment, so it is of great significance to understand their environmental transformation and toxicity. This study investigated the aqueous photochemical behavior of four OH-PAHs, 9-Hydroxyfluorene (9-OHFL), 2-Hydroxyfluorene, 9-Hydroxyphenanthrene and 1-Hydroxypyrene, under simulated sunlight irradiation ( λ > 290 nm). It was observed that their photodegradation followed the pseudo-first-order kinetics. Based on the determined quantum yields, their calculated solar apparent photodegradation half-lives in surface waters at 45° N latitude ranged from 0.4 min for 9-Hydroxyphenanthrene to 7.5 × 10 3 min for 9-OHFL, indicating that the OH-PAHs would intrinsically photodegrade fast in sunlit surface waters. Furthermore, 9-OHFL as an example was found to undergo direct photolysis, and self-sensitized photooxidation via OH rather than 1 O 2 in pure water. The potential photoreactions involved photoinduced hydroxylation, dehydrogenation and isomerization based on product identification by GC–MS/MS. 9-OHFL photodegraded slower in natural waters than in pure water, which was attributed to the integrative effects of the most photoreactive species, such as Fe(III), NO 3 − , Cl − and humic acid. The photomodified toxicity was further examined using Vibrio fischeri , and it was found that the toxicity of photolyzed 9-OHFL did not decrease significantly ( p > 0.05) either in pure water or in seawater, implying the comparable or higher toxicity of some intermediates. These results are important for assessing the fate and risks of OH-PAHs in surface waters. [ABSTRACT FROM AUTHOR]

Distribution of 12 selected polybrominated diphenyl ethers (PBDEs) was characterized in soil, moss and reindeer dung samples collected simultaneously at Ny-Ålesund of the Arctic. The average PBDE concentrations were 42 pg/g (dry weight) in soil, 122 pg/g in moss and 72 pg/g in reindeer dung. Significant log/log-linear relationship was observed between the soil/moss quotients ( Q SM ) and the sub-cooled liquid vapor pressures of PBDEs ( r 2 = 0.80). Moreover, excellent log/log-linear relationships between Q SM and the octanol/air partition coefficients as well as between the moss/dung quotient ( Q MD ) and the octanol/water partition coefficients of PBDEs were also observed, indicating that the physicochemical properties of PBDEs are appropriate parameters for characterizing the distribution of PBDEs in soil, moss and reindeer dung at Ny-Ålesund. Capsule abstract : Significant log-linear correlations were observed between physicochemical properties of PBDEs and their soil/moss (moss/dung) quotients. [ABSTRACT FROM AUTHOR]

The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives ( t d,E ) and hydroxyl-radical oxidation half-lives ( t OH,E ) in sunlit surface waters. The t d,E values range from 0.56 min to 28.8 min at 45° N latitude, whereas t OH,E ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli , and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. [ABSTRACT FROM AUTHOR]

With the exacerbating problem of antibiotic resistance, antibiotic resistance genes (ARGs) as emerging contaminants are found at elevated levels in inland aquatic environments, especially in regions of intensive agricultural and urban activity. However, little quantitative data exist on the migration and attenuation of ARGs in estuary ecosystem, which is central to predicting their fate after release into marine environment. Moreover, the relevance of multiple chemical contaminants and water quality constituents should be understood to amplify and attenuate antibiotic resistance levels. To determine the prevalence and examine the fate of sulfonamide ARGs ( sul -ARGs) in two estuaries under different effects of anthropogenic activities, we analyzed the sul -ARGs ( sul1 , sul2 , and sul3 ), class 1 integrons ( int1 ), and bacterial biomass in surface water samples from Daliaohe and Liaohe river estuaries. We also evaluated five types of antibiotics, heavy metals, and various bulk water quality constituents. Results showed that sul -ARGs were widespread in Daliaohe and Liaohe river estuaries, but the distribution did not correlate with the concentration of sulfonamides. Significant reduction in the abundance of sul -ARGs was also observed with increased salinity. Nevertheless, the trend in the change of concentrations of sul -ARGs was different in the two estuaries. Statistical analysis of the results indicated that several metals were significantly and positively correlated with sul -ARGs. Pearson's correlation coefficients were higher than those determined between antibiotic residues and sul -ARGs. Furthermore, the relative abundance of sul -ARGs was significantly and positively correlated with the relative abundance of int1 which suggested that the propagation of sul -ARGs was facilitated by class 1 integrons in estuaries. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the current Chinese regime focusing on the compensation for the environmental damages arising from the seaborne oil spill pollution was introduced, with respect to legislation infrastructure and characteristics. By now, a two-tier compensation regime, consisting of a liability scheme and a fund scheme, has already been established in China through referring to the international conventions and other states' regimes. Although its essential parts were almost identical to those of international conventions, several significant differences exist, including the norms about liability exemption and the third party liability, the fund collection and usage, as well as the amount of the levied contribution and the Special Drawing Right ceiling. With the broadens of the environmental liabilities, the longstanding issues of environmental losses arising from oil pollution have been increasingly involved in intense debates since the international conventions and some states' legislation covered them into the claim scope. A Chinese technical guideline dealing exclusively with the environmental losses was presented in detail; moreover, the differences between this guideline with the US approach were compared with respect to the compensation goals, the calculation methodologies and the compensation pathways. In the past decades, the Chinese authority has successfully settled down some famous major oil spill incidents in courts under its domestic legislation and local regulations, but the arguments on these litigations kept heated, which prompted some eco-economical experts to resolve several issues urgently, such as the compensation scope, the compulsory claim procedures, and the assessment methods of ecological compensation. Hence, some continuous efforts should be taken to explore these solutions, which are truly helpful to satisfy the requirements of the full compensation for the oil pollution damage and the marine environment protection. [Copyright &y& Elsevier]

Abstract: Gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) were collected in the atmosphere from the North Pacific to the Arctic Ocean to investigate their occurrence and gas/particle distribution. Significant linear correlations were observed between the gaseous concentrations of 9 PAHs and latitudes (r 2 = 0.69). The regression of gaseous PAHs and 1/T also gave a certain extent correlation (r 2 = 0.46). The gas/particle partition coefficients (K P) correlated well with the sub-cooled liquid vapor pressures (p o L) of PAHs with slopes higher than the theoretical value of −1, and the regressions of logK P–logp o L possessed a general tendency to intersect at a point (−2.52, −1.60). The non-linear regression of logp o L and the particle fraction displayed a more significant correlation (r 2 = 0.84) than the linear relation of logK P–logp o L (r 2 = 0.69). The influence of soot on K P was investigated, and it was found that the predicted values derived from the soot-air model agreed relatively better with the field measurements than those calculated based on the Junge–Pankow model and the K OA-based model. The results indicated that soot played an important role on the partitioning of PAHs to aerosols, and the partitioning of PAHs is more sensitive to presence of elemental carbon compared to organic matter of the aerosol. [Copyright &y& Elsevier]

Pollution status of 16 polycyclic aromatic hydrocarbons (PAHs) was investigated in coastal water of Bohai Sea, China, and ecological risks of the 4 typical PAHs (naphthalene, phenanthrene, fluoranthene, and benzo(a)pyrene) were assessed using probabilistic risk assessment approach. The average concentration of total 16 PAHs was 3504 ng/L, and 3- and 4-ring PAHs were the dominant species. The probabilistic risks of the four typical PAHs were calculated using probability density function curve and joint probability distribution curve. The maximum acceptable ecological risks of 95% of the species being unaffected for the 4 compounds were 0.004, 0.035, 0.135, and 0.010, respectively. The joint ecological risk of the four PAHs was higher than the summation of their individual ecological risks, revealing that the summation of the calculated ecological risk of PAH mixtures underestimated their integrated ecological risks when they co-existed in aquatic environment. [ABSTRACT FROM PUBLISHER]

A novel method for distinguishing heavy fuel oils from crude oils is proposed in this study. This method comprises gas chromatography-mass spectrometry analysis and principal component analysis (PCA) of the diagnostic ratios of selected polycyclic aromatic hydrocarbons (PAHs). The method was applied to 15 heavy fuel oils (B1 to B15) and 32 crude oils (C1 to C32) for distinction. Oil samples were collected from Turkmenistan,Korea, China,Vietnam,Morocco, Algeria, Sultan, Yemen, Saudi Arabia, Argentina,Russia, Indonesia, Brazil, Equatorial Guinea, Angola, and Mauritania. The discriminative power of PCA was enhanced through the selection oftypicalPAH diagnostic ratios, which could be used to distinguish petrogenic from pyrogenic PAHs. The two principal components (PC1 and PC2) account for over 75% of the variance. The method was confirmed to be highly efficient for distinguishing heavy fuel oils from crude oils, with a rapid and objective procedure under comprehensive considerations. [ABSTRACT FROM PUBLISHER]

Present study described a simple, environmental benign, easy to operate, and determination method for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil, and tebuconazole. The method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction coupled to HPLC with ultraviolet detector. In the enrichment procedure, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM][PF6] was used as the extraction solvent. Variable affecting parameters such as the volume of [C8MIM][PF6], temperature, extraction time, centrifuging time, and salting-out effect have been optimized in detail. Under the optimal conditions, this method has been found to have good linear relationship in the concentration range of 1.0-100 μg/L and excellent detection sensitivity with LODs ( S/ N = 3) in the range of 0.32-0.79 μg/L. Precisions of proposed method were in the range of 3.7-5.9% for intraday and 7.8-11.0% for interday ( RSDs, n = 6). The proposed method was used for the analysis of real water samples and good spiked recoveries at two different spiked levels were achieved in the range of 84.6-102%. [ABSTRACT FROM AUTHOR]

The goal of present study was to investigate the applicability of nanoscale zerovalent iron (NZVI) on the degradation of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea (CCU) under aerobic and anaerobic conditions, respectively. The experimental results showed that NZVI could effectively degrade CCU, but the removal efficiencies were different under these two different conditions. The best removal efficiencies for CCU were 90.2 and 75.8% under aerobic and anaerobic conditions, respectively. The highly oxidative hydroxyl radicals and reductively hydrogen would account for the rapid degradation of CCU under aerobic and anaerobic conditions, respectively. The experimental results also showed that surfactant Tween 20 significantly inhibited the degradation of CCU under aerobic conditions. However it markedly enhanced the degradation of CCU under anaerobic condition. [ABSTRACT FROM PUBLISHER]

Dioxin-like polychlorinated biphenyls (PCBs) are a class of toxic and persistent chemicals that are often found in the environment. The determination of dioxin-like PCBs in Fildes Peninsula, Antarctica, is reported in this paper. Dioxin-like PCBs were widely distributed in Antarctic soil and moss with concentration of 2.23-27.2 pg/g in soil and 10.4-812 pg/g in moss. The highest concentrations were found in the Ardley Island area and the lowest concentrations on the west coast. The contribution of PCB-118 to the ΣPCBs ranged from 36.0% to 69.6% in soil, and 17.2% to 43.4% in moss. The congener specific patterns in soil and moss were similar. Long-range atmospheric transport is thought to be the main source of PCBs detected on King George Island. The ΣPCBs toxic equivalent (TEQ) in soil was 0.400×10 to 516×10 pg (TEQ)/g with a mean value of 147×10 pg (TEQ)/g. PCB-126 had the largest contribution (81.1%) to the ΣPCBs TEQ in soil. The ΣPCBs TEQ in moss ranged from 2.90×10 to 1.19 pg/g with a mean value of 0.482 pg/g. PCB-126 was also the largest contributor (91.4%) to the ΣPCBs TEQ in moss. The mean TEQ in moss was about 40 times that in soil. [ABSTRACT FROM AUTHOR]

Three extraction techniques have been recently used for the quantitative extraction of semi-volatile organic pollutants in sediments, i.e. accelerated solvent extraction (ASE), microwave assisted extraction (MAE) and ultrasonic assisted extraction (UAE). However, their extraction efficiencies have rarely been quantitatively compared using rigorous mathematical methods. In this paper, one-way analysis of variance (ANOVA) was employed to evaluate the performance of ASE, MAE and UAE in the overall extraction of PCBs, DDTs and HCHs by analysis of their recoveries from the Standard Reference Material IAEA-417, a sediment sample certified by many international laboratories. Conclusions were drawn at a significance level of P ≤ 0.05. No significant differences were found among the mean values for method recoveries using ASE, MAE and UAE. The mean values for real recoveries using ASE and MAE were nearly identical, but the real recovery using UAE was much lower. The concentrations of all PCBs, DDTs and HCHs except for CB52 and o,p′-DDT using UAE were the lowest. Comparing the results obtained using ASE with MAE, the concentrations of CB28, CB52, CB138, α-HCH, β-HCH, p,p′-DDE and p,p′-DDD were nearly identical, while the concentrations of other compounds were significantly different. Based on the low recoveries, it was concluded that UAE is a relatively inefficient extraction method, while ASE and MAE are equivalent methods. Taking into consideration the relative standard deviation (RSD) values, solvent volume, extraction time, and purchasing costs of the apparatus, MAE was considered superior to ASE for extraction of PCBs, DDTs and HCHs. [ABSTRACT FROM AUTHOR]

An improved method, factor analysis with nonnegative constraints (FA-NNC) was employed to determine the source contributions of soil polycyclic aromatic hydrocarbons (PAHs) in Liaoning province, China, based on the measured PAH concentrations of 45 surface soil samples. The summation of 14 PAHs (Σ PAHs) ranged from 125 to 4115 ng/g dry weight with a median value of 533 ng/g. The high proportion of phenanthrene (Phe) (18.3%) implied that PAHs mainly originated from coal and/or biomass combustion. According to the results obtained from the FA-NNC, four sources were identified representing coal combustion, coke oven, biomass burning, and a labeled “other” source that may be a mixture profile. The contributions of these sources were quantified as 50.5% from coal combustion, 27.0% from coke oven, 19.4% from biomass burning and 3.1% from the “other” source. The results were compatible with emission estimation based on annual fuel consumption in the study area and emission factors of PAHs. [ABSTRACT FROM AUTHOR]

Congener specific distributions of polybrominated diphenyl ethers (PBDEs) were investigated in sediment and mussel (Mytilus edulis) collected from the coast of Bo Sea, China. The median values of BDE-209 and ΣPBDEs (including BDE-17, -28, -47, -66, -71, -85, -99, -100, -138, -153, -154, -183 and -190) were 2.29 and 0.16ngg−1 dry weight in sediment, and 2.43 and 0.68ngg−1 dry weight in mussel, respectively. BDE-209 was the predominant congener (61–99% in mussel and 75–99% in sediment except for one sample with 17%). Different congener patterns (excluding BDE-209) were observed between sediment and mussel, which were attributed to individual congener’s bioaccumulation potential and/or the ability to metabolize. The four most abundant congeners were BDE-47 (40.3%), -99 (22.5%), -71 (8.9%) and -28 (5.8%) in sediment, and -47 (36.4%), -28 (14.5%), -154 (8.6%) and -71 (8.6%) in mussel, respectively. The ratios of BDE-47/BDE-99 and BDE-100/BDE-99 in sediment were lower than those in mussel, indicating higher transformation and uptake rate of BDE-99 in mussel. The biota-sediment accumulation factor (BSAF) of individual PBDE congeners declined with the increase of their logarithm of octanol–water partition coefficients (log K OW) except for BDE-154, indicating congeners with higher log K OW were more likely to retain in sediment. These can be explained with a high affinity of these compounds for carbonaceous geosorbents, and molecular steric hindrance that limits large, very hydrophobic organic compounds from penetrating the cellular membranes. [Copyright &y& Elsevier]

Solid-phase microextraction (SPME) coupled to high performance liquid chromatography and fluorimetric detection has been developed for the analysis of three endocrine disruptors: bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol. Several kinds of commercially available coating fibers were evaluated for their extraction efficiency to the target analytes and the carbowax/templated resin (CW/TPR) coating fiber was found to be the best one. The parameters affecting the extraction efficiency, such as absorption time, extraction temperature, pH values of the sample solutions, agitating rate, salting-out effect, desorption mode, composition of the desorption eluent, and the flow rate of mobile phase at the desorption stage, were investigated and optimized. The chromatographic conditions were also examined. The developed method has been used to determine bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol in several spiked natural water samples and good recovery results (93.9–108.2%) were obtained. Detection limits of 0.43, 0.16, and 0.29 ng mL−1 for bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol, respectively, were achieved under the optimized conditions. [ABSTRACT FROM AUTHOR]

To date, the impact of air-sea exchange on spatial distribution of atmospheric methane (CH 4 hereafter) remains less understood in the coastal areas of China. Here we measured the dissolved and atmospheric CH 4 in the Dalian Bay and adjacent area in July and August 2014, respectively. Results showed that the study area was a net significant source of atmospheric CH 4 , with a mean sea-to-air CH 4 flux of 170.6 ± 149.5 μmol/(m2·day). We optimized a method to accurately quantify the elevated atmospheric CH 4 mole fraction (△CH 4 hereafter) caused by air-sea exchange. The calculated △CH 4 in the study area ranged from 15.4 to 102.1 nmol/mol, 1.5–10.2 nmol/mol, and 0.03–0.22 nmol/mol at the mixing height of 1, 10, and 471 m, respectively. The △CH 4 mole fractions caused by air-sea exchange were positive with sea-to-air CH 4 flux and in situ observed atmospheric CH 4 mole fraction, while negative with altitude. Under the standard conditions, we defined 50.8 μmol/(m2·day) as the criteria value of sea-to-air CH 4 flux which could result in a detectable elevation atmospheric CH 4 mole fraction at a height of 10 m. Image 106245 • Coastline is an intensive ventilated area for CH 4 in the study area. • A method was improved for quantifying the impact of air-sea exchange on atmospheric CH 4. • Air-sea exchange induced atmospheric CH 4 mole fraction decreasing with increasing altitude. • A criterion flux value was defined for studying the impact of air-sea CH 4 exchange. [ABSTRACT FROM AUTHOR]