After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, d...After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.展开更多
Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)ev...Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)even at trace level(nmol/mol)are usually involved in cell construction and further H_(2)production,which would cause degradation of the catalysts and shorten the lifetime of the fuel cells.Moreover,the highly reactive SCs could cause varied species and concentrations of them in complex matrices,so online rather than offline analysis of SCs in H_(2)would be preferred.In this context,we developed a new system combining online cryogenic preconcentration of nine SCs and subsequent determination by GC-SCD(sulfur chemiluminescent detector),with the correlation coefficients of the calibration curves higher than 0.999,calculated limits of detection no higher than 0.050 nmol/mol,analytical time around 30 min per sample,and satisfactory precision and accuracy(RSD<5%and SD<15%).The analytical performance was much better than or at least comparable to the previously reported and the developed system was successfully applied for real sample analysis.展开更多
The solid-phase extraction using Pd-Al2O3 as the stationary phase was employed to pre-separate the sulfur compounds in straight-run diesel. The isolating effect was evaluated quantitatively by gas chromatography with ...The solid-phase extraction using Pd-Al2O3 as the stationary phase was employed to pre-separate the sulfur compounds in straight-run diesel. The isolating effect was evaluated quantitatively by gas chromatography with a sulfur chemiluminescence detector to harvest a satisfactory result. The identification of the structure of sulfur compounds by comprehensive two-dimensional gas chromatography coupled with the time-of-flight mass spectrometry indicated that cyclo-sulfides, benzothiophenes, dibenzothiophenes, dihydro-benzothiophenes and tetrahydro-dibenzothiophenes were included in straightrun diesel obtained from the Arab medium crude(AM). A total of 259 individual compounds were detected and their molecular structures were identified. The analytical method was approved as an effective way to characterize the composition of sulfur compounds, which reduced the interference of other compounds, facilitated the data presentation and provided more detailed information about molecular composition of sulfur compounds.展开更多
Adsorption desulfurization performance of Na Y,HY and Ce HY zeolites is evaluated in a miniature fixedbed flow by model gasoline containing with thiophene,tetrahydrothiophene,2-methylthiophene,benzothiophene or mixed ...Adsorption desulfurization performance of Na Y,HY and Ce HY zeolites is evaluated in a miniature fixedbed flow by model gasoline containing with thiophene,tetrahydrothiophene,2-methylthiophene,benzothiophene or mixed sulfur compounds.The structural properties of adsorbents are characterized by XRD,N2-adsorption and XPS techniques.Adsorption desulfurization mechanisms of these sulfur compounds over the specific active sites of adsorbents as a major focus of this work,have been systematically investigated by using in situ FT-IR spectroscopy with single and double probing molecules.Desulfurization experimental results show that the Ce HY adsorbent exhibits superior adsorption sulfur capacity at breakthrough point of zero sulfur for ultra-deep removal of each thiophenic sulfur compound,especially in the capture of aromatic 2-methylthiophene(about ca.28.6 mgS/gadsorbent).The results of in situ FT-IR with single probing molecule demonstrate an important finding that high oligomerization ability of thiophene or 2-methylthiophene on the CeHY can promote the breakthrough adsorption sulfur capacity,mainly resulting from the synergy between Br?nsted acid sites and Ce(III)hydroxylated species active sites located in the supercages of Ce HY.Meanwhile,the result of in situ FT-IR with double probing molecules further reveals the essence of oligomerization reactions of thiophene and 2-methylthiophene molecules on those specific active sites.By contrast,the oligomerization reaction of benzothiophene molecules on the active sites of Ce HY cannot occur due to the restriction of cavity size of supercages,but they can be adsorbed on the Br?nsted acid sites via protonation,and on Ce(III)hydroxylated species and extra-framework aluminum hydroxyls species via direct"S-M"bonding interaction.As to the tetrahydrothiophene,adsorption mechanism is similar to that of benzothiophene,except in the absence of protonation.The paper can provide a new design idea of specific adsorption active sites in excellent desulfurization adsorbents for elevating higher quality of FCC gasoline in the future.展开更多
Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batt...Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batteries.In this paper,properties of intrinsic B or Si single-atom doped,and B-Si codoped graphene(GR)and graphdiyne(GDY)were investigated by using density functional theory-based calculations,in which the optimal doping configurations were explored for potential applications in adsorbing sulfur compounds.Results showed that both B or Si single-atom doping and B-Si codoping could substantially enhance the electron transport properties of GR and GDY,improving their surface activity.Notably,B and Si atoms displayed synergistic effects for the codoped configurations,where B-Si codoped GR/GDY exhibited much better performance in the adsorption of sulfurcontaining chemicals than single-atom doped systems.In addition,results demonstrated that,after B-Si codoping,the adsorption energy and charge transfer amounts of GDY with sulfur compounds were much larger than those of GR,indicating that B-Si codoped GDY might be a favorable material for more effectively interacting with sulfur reagents.展开更多
The effect of olefins on formation of sulfur compounds in FCC gasoline was studied in a small-scale fixed fluidized bed （FFB） unit at temperatures ranging from 400℃ to 500℃, a weight hourly space velocity （WHSV）...The effect of olefins on formation of sulfur compounds in FCC gasoline was studied in a small-scale fixed fluidized bed （FFB） unit at temperatures ranging from 400℃ to 500℃, a weight hourly space velocity （WHSV） of 10 h-1, and a catalyst/oil ratio of 6. The results showed that C4--C6 olefins contained in the FCC gasoline could react with HzS to form predominantly thiophenes, alkyl-thiophenes as well as a fractional amount of thiols, while large molecular olefins such as heptene could react with hydrogen sulfide to form benzothiophenes. The amount of sulfur compounds formed at different tem- peratures over different catalysts were in proportion to the mass fractions of olefins in the feedstock, with the amount of sulfur compounds formed over REUSY catalyst exceeding those formed over the shape selective zeolite catalyst owing to the effect of catalyst performance and the impact of catalyst on the degree of olefin conversion. The amount of sulfur compounds generated and their increase reached a maximum at 450℃ and a minimum at 400℃ because of the influence of temperature on the thermodynamic and kinetic constants for formation of sulfur compound as well as on the olefin conversion degree. Based on the above-mentioned study, a reaction network and a model for prediction of sulfur compounds generated upon reaction of olefins in FCC gasoline with HES were established.展开更多
Sulfur-containing compounds(SCCs)must be removed from fuels before use.In this study,a novel non-noble metal Fe single-atom adsorbent(SA-Fe/CN)was synthesized using a core-shell strategy and applied for the adsorptive...Sulfur-containing compounds(SCCs)must be removed from fuels before use.In this study,a novel non-noble metal Fe single-atom adsorbent(SA-Fe/CN)was synthesized using a core-shell strategy and applied for the adsorptive removal of benzothiophene(BT)and dibenzothiophene(DBT).The adsorption isotherms,thermodynamics,kinetics,and adsorption-regeneration cycles of DBT and BT on SA-Fe/CN were studied.SA-Fe/CN exhibited a significant capacity to adsorb DBT,and the isothermal equilibrium was well described by the Langmuir isotherm.The Gibbs free energy values were negative(ΔG^(0)<0),indicating that the adsorption of DBT and BT was favored and spontaneous.The adsorption process conformed to the pseudo-second-order kinetic model with high R^(2) values(0.9994,0.9987).The adsorption capacity of SA-Fe/CN for DBT and BT reached 163.21 mg/g and 90.35 mg/g,respectively,due to the highly active sites of the single atom and electrostatic interaction with the sulfide.Therefore,SA-Fe/CN may be a promising adsorbent for SCC removal.展开更多
The emissions of volatile sulfur compounds(VSCs)from wastewater treatment plants(WWTPs)pose odor nuisances and health risks to workers and surrounding residents,thus becoming a major environmental concern for these fa...The emissions of volatile sulfur compounds(VSCs)from wastewater treatment plants(WWTPs)pose odor nuisances and health risks to workers and surrounding residents,thus becoming a major environmental concern for these facilities.This study investigated the long-term monitoring of emissions of VSCs from an anaerobic/oxic(A/O)WWTP and employed the AERMOD model to simulate the dispersion of VSCs within an area of 5×5 km^(2) for assessing the impact of these emissions on odor and health risks.The obtained results indicated that the emissions of VSCs from the WWTP decreased in the order of summer>autumn>spring>winter.The pretreatment unit accounted for 90.72%of the total VSCs emissions.The dispersion of VSCs was significantly influenced by the direction and speed of wind,with the largest dispersion range observed in autumn and the smallest one in spring.Dimethyl disulfide(DMDS),dimethyl sulfide(DMS),and hydrogen sulfide(H_(2)S)were identified as the primary VSCs contributing to odor impacts.The source tracing analysis revealed that the fugitive emissions of VSCs from the grill and sand-water separation unit(SWSU)contributed most significantly to their dispersion,odor pollution,and health risks,accounting for 74.87%and 11.33%,respectively.Enclosure of the grill and SWSU with covers,adjustment of the position of the exhaust pipe of the deodorizing facility,and increment in the height of the exhaust pipe are expected to be effective measures in mitigating the negative impacts of VSCs.These measures would provide new insights into dispersion modelling,risk prediction,and emission control of gaseous pollutant emitted from other factories.展开更多
Routine GC/MS analysis may apply to the volatilized Low-Molecular-Weight compounds in saturate and aromatic hydrocarbon fractions;thus,relative studies using this technique inevitably bring about some limitations on d...Routine GC/MS analysis may apply to the volatilized Low-Molecular-Weight compounds in saturate and aromatic hydrocarbon fractions;thus,relative studies using this technique inevitably bring about some limitations on distribution of miscellaneous sulfur atom.In this article,Fourier Transform Ion Cyclotron Resonance Mass Spectrometry(FT-ICR MS)with high resolution is employed to investigate the distribution of organic sulfur compounds(OSCs)in the crude oil typically derived from the Eogene carbonate-evaporite sediments with further chemical compositional characterization in molecular level by miscellaneous atomic type,carbon number,and double bond equivalent(DBE).A variety of miscellaneous atomic types with S1,S2,S3,OS,OS2,O2S,O2S2,NS,and NOS etc.(S1 means those OSCs with one sulfur atom in a molecule)were identified in OSCs in these oil samples.High levels of alkyl thioether series compounds with one ring structure were presented mainly in the crude oil in the Jianghan Basin whereas high amounts of benzothiophene,dibenzothiophene etc.compounds with higher values in DBE and carbon number range occurred in the sulfur-rich heavy oil in the Jinxian Sag.Although carbonate-evaporite sediments deposited in the saline lacustrine facies in the Eogene basin both occurred in the Jinxian Sag and Jianghan Basin,obviously,they possess different chemical diagenetic pathway of sulfur under various microbial reactions,leading to diverse distributional characteristics on biomarkers,OSCs,and even different hydrocarbon generation mechanism of immature crude oil.展开更多
A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced cataly...A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.展开更多
Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evoluti...Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon（δ^（13）C） and organic carbon（δ^（13）C_（org）） isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate（CAS, δ^（34）S_（CAS）） and pyrite（δ^（34）S_（pyrite））, unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ^（13）C_（carb） of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ^（34）S_（CAS） and δ^（34）S_（pyrite） have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound（VOSC, such as methanethiol and dimethyl sulfide） formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of ^（32）S from continental margins to open oceans, elevating δ^（34）S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.展开更多
Photocatalytic aerobic oxidative desulfurization(PAODS)is an emerging green and sustainable method for fuel desulfurization.However,the sluggish conversion kinetics of refractory sulfur compounds pose a significant ch...Photocatalytic aerobic oxidative desulfurization(PAODS)is an emerging green and sustainable method for fuel desulfurization.However,the sluggish conversion kinetics of refractory sulfur compounds pose a significant challenge for current photocatalysts.Here we report a P-doped ZnCoO porous nanosheet photocatalyst co-modified with ultrasmall MoO_(x)and Pt clusters for boosting the photocatalytic conversion of thiophenic organic sulfur compounds.Through experimental characterization and theoretical calculations,we demonstrate that MoO_(x)and Pt function as oxidation and reduction cocatalysts,respectively,significantly improving photocatalytic efficiency by facilitating effective charge separation,accelerating surface reactions,and providing active sites for the oxidation reaction.The catalyst achieves an exceptional mass-specific activity of 10.40 mmol g^(-1)h^(-1)in the oxidation of dibenzothiophene(DBT),and more importantly,enables deep desulfurization of real diesel,underscoring its practical applicability in an industrial setting.This work provides both foundational insights and technical advancements for the development of efficient photocatalysts in carbon-neutral PAODS processes.展开更多
The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： t...The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： the addition of either cornstalks（CS） or wood peat（WP） to kitchen waste as a bulking agent before biodrying, and a control treatment（CK）. The water-removal rates for CK, CS, and WP treatments were 0.35, 0.56, and0.43 kg/kg, respectively. Addition of bulking agents to kitchen waste produced less leachate,higher moisture-removal rates, and lower consumption of volatile solids. The CS treatment had the highest biodrying index（4.07）, and those for the WP and CK treatments were 3.67 and 1.97, respectively. Adding cornstalks or wood peat decreased NH3 emissions by 55.8%and 71.7%, respectively. Total sulfur losses were 3.6%–21.6% after 21 days biodrying, and H2 S and Me2 SS were the main（〉 95%） sulfur compounds released. The smallest amounts of sulfur-containing odorous compounds were emitted when cornstalks were added, and adding cornstalks and wood peat decreased total sulfur losses by 50.6%–64.8%.展开更多
Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate bl...Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration （close to 0 mg/L）, low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe^2＋ and ∑S2- were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.展开更多
Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liqu...Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.展开更多
Methanethiol(MT) produced from terrestrial soils can have important effects on atmospheric chemistry and ecosystem-level processes, and it originates mainly from the metabolism of sulfur-containing amino acids by micr...Methanethiol(MT) produced from terrestrial soils can have important effects on atmospheric chemistry and ecosystem-level processes, and it originates mainly from the metabolism of sulfur-containing amino acids by microorganisms.Methanethiol producing bacteria(MPB) were enriched and isolated from agricultural soils in a modified basal medium containing methionine(Met) as the sole carbon source.The isolates were identified as Bacillus sp.WH-R1, WH-R2, and WH-R3; Arthrobacter sp.SZLB-W3; and Delftia sp.CHZG-R4 based on cell morphology, physiological and biochemical characteristics, and 16 S r RNA sequence analysis.Delftia sp.CHZG-R4 was identified as a novel strain producing MT using Met as a precursor, and it had the most active MT-producing potential, with the production of MT being 21.8 μg at 30℃ and pH 7.0.Optimal MT production was observed at 35℃ and pH6.0, with 51.3% of sulfur content in Met being converted into MT.Under these conditions, MT production changed according to the supply of both carbon and nitrogen sources.The addition of 2 g L^(-1) each of starch, sucrose, urea, and potassium nitrate promoted MT production by more than 10%, whereas addition of 2 g L^(-1) each of ammonia sulfate and peptone decreased MT production by16% and 87%, respectively.This is the first study to report MT production by Delftia sp.CHZG-R4, providing useful information for the microbial mechanism of MT production from agricultural soils.Our findings also contribute to improving our knowledge of the function of Delftia sp.CHZG-R4.展开更多
The complexation of Pb^（2＋）by diallyl disulfide（DADS）, dimethyl disulfide（DMDS） and diallyl sulfide（DAS）has been studied by differential pulse voltammetry. Stability constants,（log b）, of the 1：1（PbL） an...The complexation of Pb^（2＋）by diallyl disulfide（DADS）, dimethyl disulfide（DMDS） and diallyl sulfide（DAS）has been studied by differential pulse voltammetry. Stability constants,（log b）, of the 1：1（PbL） and 1：2（PbL_2） complexes, where L = ligand, were found to be in the range of ca. 3.8-4.2 and 9.4-10.2,respectively. Complex formation is accompanied with a significant decrease in the peak current and the shift of the Pb2＋/Pb half-wave potential to a higher one upon the addition of the sulfur containing ligands（L）. The formation of 1：1 and 1：2 complexes, i.e., PbL^（2＋）and PbL_2^（2＋）was observed in the case of the three ligands. The consecutive formation constants of labile lead complexes with DADS, DMDS, and DAS were determined at 298 K by the method of De Ford and Hume. Apparently due to the large size of the lead ion,steric hindrance caused by the greater steric bulk of DADS compared to that of DMDS have little or no effects on the formation constants, so that very similar values were obtained in the case of the two ligands. Also, the possible participation of C=C double bonds in coordination with the metal center in the case of DADS appears to compensate for the steric effects caused by the larger size of this ligand. In agreement with the Jorgensen principle of symbiosis, the second formation constants were found to be approximately six orders of magnitude greater than the first ones.展开更多
“High nutrient, low chlorophyll (HNLC)” regions were created by locking iron into sedimentary iron sulfides with hydrogen sulfide available from volcanic eruptions in surrounding oceans. Appropriate locations and de...“High nutrient, low chlorophyll (HNLC)” regions were created by locking iron into sedimentary iron sulfides with hydrogen sulfide available from volcanic eruptions in surrounding oceans. Appropriate locations and deployment methods for the iron fertilization were far from volcanoes, earthquakes and boundaries of tectonic plates to reduce the chance of iron-locking by volcanic sulfur compounds. The appropriate locations for the large-scale iron fertilization are proposed as Shag Rocks in South Georgia and the Bransfield Strait in Drake Passage in the Southern Ocean due to their high momentum flux causing efficient iron deployment. The iron (Fe) replete compounds, consisting of natural clay, volcanic ash, agar, N<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">-fixing mucilaginous cyanobacteria, carbon black, biodegradable plastic foamed polylactic acid, fine wood chip, and iron-reducing marine bacterium, are deployed in the ocean to stay within a surface depth of 100<span style="font-family:""> <span style="font-size:12px;font-family:Verdana;"><span style="font-size:12px;font-family:Verdana;"><span style="font-family:Verdana;font-size:12px;">m for phytoplankton digestion. The deployment method of Fe-replete composite with a duration of at least several years for the successful iron fertilization, is configured to be on the streamline of the Antarctic Circumpolar Current (ACC). This will result in high momentum flux for its efficient dispersion on the ocean surface where diatom, copepods, krill and humpback whale stay together (~100<span style="font-family:""> <span style="font-family:""><span style="font-size:12px;font-family:Verdana;">m). Humpback whales are proposed as a biomarker for the successful iron fertilization in large-scale since humpback whales feed on krill, which in turn feed on cockpods and diatoms. The successful large-scale iron fertilization may be indicated by the return of the humpback whales if they could not be found for a long period before the iron fertilization. On-line monitoring for the successful iron fertilization focuses on the simultaneous changes of the following two groups;the increase concentration group (chlorophyll, O<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">, Dissolved Oxygen (DO), Di Methyl Sulfide (DMS)) and the decrease concentration group (nitrate, phosphate, silicate, CO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">, Dissolved CO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;"> (DCO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">)). The monitoring of chlorophyll-<span style="font-size:12px;font-family:Verdana;">a<span style="font-size:12px;font-family:Verdana;">, nitrate phosphate, and silicate concentrations after deploying the Fe-replete complex is carried out throughout the day and night for the accurate measurement of algal blooms.展开更多
基金supported by the National Natural Science Foundation of China (No. 50979102, 40730528,40901252, 20907057)
文摘After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.
基金the financial support to this work by Sichuan Science and Technology,China(Nos.2019ZDZX0035&2018TZDZX0008)the Ministry of Education through the 111 Project(No.B17030).
文摘Hydrogen fuel cells are among the promising energy sources worldwide,which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts.However,sulfur compounds(SCs)even at trace level(nmol/mol)are usually involved in cell construction and further H_(2)production,which would cause degradation of the catalysts and shorten the lifetime of the fuel cells.Moreover,the highly reactive SCs could cause varied species and concentrations of them in complex matrices,so online rather than offline analysis of SCs in H_(2)would be preferred.In this context,we developed a new system combining online cryogenic preconcentration of nine SCs and subsequent determination by GC-SCD(sulfur chemiluminescent detector),with the correlation coefficients of the calibration curves higher than 0.999,calculated limits of detection no higher than 0.050 nmol/mol,analytical time around 30 min per sample,and satisfactory precision and accuracy(RSD<5%and SD<15%).The analytical performance was much better than or at least comparable to the previously reported and the developed system was successfully applied for real sample analysis.
基金financially supported by the National Basic Research Program of China (973 Program) (2012CB224800)
文摘The solid-phase extraction using Pd-Al2O3 as the stationary phase was employed to pre-separate the sulfur compounds in straight-run diesel. The isolating effect was evaluated quantitatively by gas chromatography with a sulfur chemiluminescence detector to harvest a satisfactory result. The identification of the structure of sulfur compounds by comprehensive two-dimensional gas chromatography coupled with the time-of-flight mass spectrometry indicated that cyclo-sulfides, benzothiophenes, dibenzothiophenes, dihydro-benzothiophenes and tetrahydro-dibenzothiophenes were included in straightrun diesel obtained from the Arab medium crude(AM). A total of 259 individual compounds were detected and their molecular structures were identified. The analytical method was approved as an effective way to characterize the composition of sulfur compounds, which reduced the interference of other compounds, facilitated the data presentation and provided more detailed information about molecular composition of sulfur compounds.
基金financially supported by the National Natural Science Foundation of China (Nos. U1662135 and 21376114, 21076100)by the China National Petroleum Corporation (Grant No. 1001A-01-01-01)
文摘Adsorption desulfurization performance of Na Y,HY and Ce HY zeolites is evaluated in a miniature fixedbed flow by model gasoline containing with thiophene,tetrahydrothiophene,2-methylthiophene,benzothiophene or mixed sulfur compounds.The structural properties of adsorbents are characterized by XRD,N2-adsorption and XPS techniques.Adsorption desulfurization mechanisms of these sulfur compounds over the specific active sites of adsorbents as a major focus of this work,have been systematically investigated by using in situ FT-IR spectroscopy with single and double probing molecules.Desulfurization experimental results show that the Ce HY adsorbent exhibits superior adsorption sulfur capacity at breakthrough point of zero sulfur for ultra-deep removal of each thiophenic sulfur compound,especially in the capture of aromatic 2-methylthiophene(about ca.28.6 mgS/gadsorbent).The results of in situ FT-IR with single probing molecule demonstrate an important finding that high oligomerization ability of thiophene or 2-methylthiophene on the CeHY can promote the breakthrough adsorption sulfur capacity,mainly resulting from the synergy between Br?nsted acid sites and Ce(III)hydroxylated species active sites located in the supercages of Ce HY.Meanwhile,the result of in situ FT-IR with double probing molecules further reveals the essence of oligomerization reactions of thiophene and 2-methylthiophene molecules on those specific active sites.By contrast,the oligomerization reaction of benzothiophene molecules on the active sites of Ce HY cannot occur due to the restriction of cavity size of supercages,but they can be adsorbed on the Br?nsted acid sites via protonation,and on Ce(III)hydroxylated species and extra-framework aluminum hydroxyls species via direct"S-M"bonding interaction.As to the tetrahydrothiophene,adsorption mechanism is similar to that of benzothiophene,except in the absence of protonation.The paper can provide a new design idea of specific adsorption active sites in excellent desulfurization adsorbents for elevating higher quality of FCC gasoline in the future.
基金the support of the National Natural Science Foundation of China(Grant No.51472074).
文摘Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batteries.In this paper,properties of intrinsic B or Si single-atom doped,and B-Si codoped graphene(GR)and graphdiyne(GDY)were investigated by using density functional theory-based calculations,in which the optimal doping configurations were explored for potential applications in adsorbing sulfur compounds.Results showed that both B or Si single-atom doping and B-Si codoping could substantially enhance the electron transport properties of GR and GDY,improving their surface activity.Notably,B and Si atoms displayed synergistic effects for the codoped configurations,where B-Si codoped GR/GDY exhibited much better performance in the adsorption of sulfurcontaining chemicals than single-atom doped systems.In addition,results demonstrated that,after B-Si codoping,the adsorption energy and charge transfer amounts of GDY with sulfur compounds were much larger than those of GR,indicating that B-Si codoped GDY might be a favorable material for more effectively interacting with sulfur reagents.
文摘The effect of olefins on formation of sulfur compounds in FCC gasoline was studied in a small-scale fixed fluidized bed （FFB） unit at temperatures ranging from 400℃ to 500℃, a weight hourly space velocity （WHSV） of 10 h-1, and a catalyst/oil ratio of 6. The results showed that C4--C6 olefins contained in the FCC gasoline could react with HzS to form predominantly thiophenes, alkyl-thiophenes as well as a fractional amount of thiols, while large molecular olefins such as heptene could react with hydrogen sulfide to form benzothiophenes. The amount of sulfur compounds formed at different tem- peratures over different catalysts were in proportion to the mass fractions of olefins in the feedstock, with the amount of sulfur compounds formed over REUSY catalyst exceeding those formed over the shape selective zeolite catalyst owing to the effect of catalyst performance and the impact of catalyst on the degree of olefin conversion. The amount of sulfur compounds generated and their increase reached a maximum at 450℃ and a minimum at 400℃ because of the influence of temperature on the thermodynamic and kinetic constants for formation of sulfur compound as well as on the olefin conversion degree. Based on the above-mentioned study, a reaction network and a model for prediction of sulfur compounds generated upon reaction of olefins in FCC gasoline with HES were established.
文摘Sulfur-containing compounds(SCCs)must be removed from fuels before use.In this study,a novel non-noble metal Fe single-atom adsorbent(SA-Fe/CN)was synthesized using a core-shell strategy and applied for the adsorptive removal of benzothiophene(BT)and dibenzothiophene(DBT).The adsorption isotherms,thermodynamics,kinetics,and adsorption-regeneration cycles of DBT and BT on SA-Fe/CN were studied.SA-Fe/CN exhibited a significant capacity to adsorb DBT,and the isothermal equilibrium was well described by the Langmuir isotherm.The Gibbs free energy values were negative(ΔG^(0)<0),indicating that the adsorption of DBT and BT was favored and spontaneous.The adsorption process conformed to the pseudo-second-order kinetic model with high R^(2) values(0.9994,0.9987).The adsorption capacity of SA-Fe/CN for DBT and BT reached 163.21 mg/g and 90.35 mg/g,respectively,due to the highly active sites of the single atom and electrostatic interaction with the sulfide.Therefore,SA-Fe/CN may be a promising adsorbent for SCC removal.
基金supported by the National Natural Science Foundation of China(Nos.52170017 and 62021003)the Beijing Nova Program(No.20240484694)the Key Laboratory of Odor Pollution Control in Ministry of Ecology and Environment(No.20230803).
文摘The emissions of volatile sulfur compounds(VSCs)from wastewater treatment plants(WWTPs)pose odor nuisances and health risks to workers and surrounding residents,thus becoming a major environmental concern for these facilities.This study investigated the long-term monitoring of emissions of VSCs from an anaerobic/oxic(A/O)WWTP and employed the AERMOD model to simulate the dispersion of VSCs within an area of 5×5 km^(2) for assessing the impact of these emissions on odor and health risks.The obtained results indicated that the emissions of VSCs from the WWTP decreased in the order of summer>autumn>spring>winter.The pretreatment unit accounted for 90.72%of the total VSCs emissions.The dispersion of VSCs was significantly influenced by the direction and speed of wind,with the largest dispersion range observed in autumn and the smallest one in spring.Dimethyl disulfide(DMDS),dimethyl sulfide(DMS),and hydrogen sulfide(H_(2)S)were identified as the primary VSCs contributing to odor impacts.The source tracing analysis revealed that the fugitive emissions of VSCs from the grill and sand-water separation unit(SWSU)contributed most significantly to their dispersion,odor pollution,and health risks,accounting for 74.87%and 11.33%,respectively.Enclosure of the grill and SWSU with covers,adjustment of the position of the exhaust pipe of the deodorizing facility,and increment in the height of the exhaust pipe are expected to be effective measures in mitigating the negative impacts of VSCs.These measures would provide new insights into dispersion modelling,risk prediction,and emission control of gaseous pollutant emitted from other factories.
基金supported by the National Basic Research Program of China(Grant No.2012CB214706)Major National Science and Technology Projects(Grant No.2011ZX05008-002-33)+1 种基金Gas Hydrate Survey in South China Sea of China(Grant No.GZH2011003-05-04-01)the National Natural Science Fundation of China(Grant Nos.40873048,41173053)
文摘Routine GC/MS analysis may apply to the volatilized Low-Molecular-Weight compounds in saturate and aromatic hydrocarbon fractions;thus,relative studies using this technique inevitably bring about some limitations on distribution of miscellaneous sulfur atom.In this article,Fourier Transform Ion Cyclotron Resonance Mass Spectrometry(FT-ICR MS)with high resolution is employed to investigate the distribution of organic sulfur compounds(OSCs)in the crude oil typically derived from the Eogene carbonate-evaporite sediments with further chemical compositional characterization in molecular level by miscellaneous atomic type,carbon number,and double bond equivalent(DBE).A variety of miscellaneous atomic types with S1,S2,S3,OS,OS2,O2S,O2S2,NS,and NOS etc.(S1 means those OSCs with one sulfur atom in a molecule)were identified in OSCs in these oil samples.High levels of alkyl thioether series compounds with one ring structure were presented mainly in the crude oil in the Jianghan Basin whereas high amounts of benzothiophene,dibenzothiophene etc.compounds with higher values in DBE and carbon number range occurred in the sulfur-rich heavy oil in the Jinxian Sag.Although carbonate-evaporite sediments deposited in the saline lacustrine facies in the Eogene basin both occurred in the Jinxian Sag and Jianghan Basin,obviously,they possess different chemical diagenetic pathway of sulfur under various microbial reactions,leading to diverse distributional characteristics on biomarkers,OSCs,and even different hydrocarbon generation mechanism of immature crude oil.
基金the financial support from the National Natural Science Foundation of China(Nos.21722604 and 21776116)China Postdoctoral Science Foundation(2020M671365)+2 种基金Jiangsu Postdoctoral Research Funding Program(No.2021K343C)Natural Science Foundation of Jiangsu Province(No.BK20190243)the Society Development Fund of Zhenjiang City(SH2020020)。
文摘A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.
基金supported by the Natural Science Founddation of China (Nos.41272017,41322021)
文摘Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon（δ^（13）C） and organic carbon（δ^（13）C_（org）） isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate（CAS, δ^（34）S_（CAS）） and pyrite（δ^（34）S_（pyrite））, unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ^（13）C_（carb） of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ^（34）S_（CAS） and δ^（34）S_（pyrite） have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound（VOSC, such as methanethiol and dimethyl sulfide） formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of ^（32）S from continental margins to open oceans, elevating δ^（34）S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.
基金supported by the National Natural Science Foundation of China(21808098)the Project of Shandong Province Higher Educational Science(2022KJ122)the Innovation and Entrepreneurship Leading Team Project of Yantai Economic and Technological Development Area(YEDA)(2023TD001)。
文摘Photocatalytic aerobic oxidative desulfurization(PAODS)is an emerging green and sustainable method for fuel desulfurization.However,the sluggish conversion kinetics of refractory sulfur compounds pose a significant challenge for current photocatalysts.Here we report a P-doped ZnCoO porous nanosheet photocatalyst co-modified with ultrasmall MoO_(x)and Pt clusters for boosting the photocatalytic conversion of thiophenic organic sulfur compounds.Through experimental characterization and theoretical calculations,we demonstrate that MoO_(x)and Pt function as oxidation and reduction cocatalysts,respectively,significantly improving photocatalytic efficiency by facilitating effective charge separation,accelerating surface reactions,and providing active sites for the oxidation reaction.The catalyst achieves an exceptional mass-specific activity of 10.40 mmol g^(-1)h^(-1)in the oxidation of dibenzothiophene(DBT),and more importantly,enables deep desulfurization of real diesel,underscoring its practical applicability in an industrial setting.This work provides both foundational insights and technical advancements for the development of efficient photocatalysts in carbon-neutral PAODS processes.
基金financially supported by the National Key Basic Research Program of China(No.2014CB643403)the National Science Fund for Distinguished Young Scholars(No.51225401)
基金financially supported by the Ministry of Science and Technology of the People's Republic of Chinathrough the High Effective Intelligent Composting Process and Key Technology Research program(No.2016YFD0800601)the project of“State Key Laboratory of Solid Waste Reuse for Building Materials”(No.SWR-2014-005)
文摘The effects of adding a bulking agent on the performance and odor emissions（ammonia and eight sulfur-containing odorous compounds） when biodrying kitchen waste were investigated. Three treatments were considered： the addition of either cornstalks（CS） or wood peat（WP） to kitchen waste as a bulking agent before biodrying, and a control treatment（CK）. The water-removal rates for CK, CS, and WP treatments were 0.35, 0.56, and0.43 kg/kg, respectively. Addition of bulking agents to kitchen waste produced less leachate,higher moisture-removal rates, and lower consumption of volatile solids. The CS treatment had the highest biodrying index（4.07）, and those for the WP and CK treatments were 3.67 and 1.97, respectively. Adding cornstalks or wood peat decreased NH3 emissions by 55.8%and 71.7%, respectively. Total sulfur losses were 3.6%–21.6% after 21 days biodrying, and H2 S and Me2 SS were the main（〉 95%） sulfur compounds released. The smallest amounts of sulfur-containing odorous compounds were emitted when cornstalks were added, and adding cornstalks and wood peat decreased total sulfur losses by 50.6%–64.8%.
基金supported by the Major National Science and Technology Programs on Water Pollution Control and Treatment (No. 2012X0713-005)the Innovation Program of the Chinese Academy of Sciences (No. KZCX2-EW-314)+2 种基金the 135 Project of Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (No. NIGLAS2012135008)the National Natural ScienceFoundation of China (No. 41103033)the IndustryUniversity-Research Prospective Joint Research Projects of Jiangsu Province (No. BY2011165)
文摘Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration （close to 0 mg/L）, low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe^2＋ and ∑S2- were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.
文摘Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.
基金supported by the Natural Science Foundation of China(Nos.41025012,41273095,and 41103067)the Major Science and Technology Program for Water Pollution Control and Treatment,China(No.2015ZX07204-007-007)
文摘Methanethiol(MT) produced from terrestrial soils can have important effects on atmospheric chemistry and ecosystem-level processes, and it originates mainly from the metabolism of sulfur-containing amino acids by microorganisms.Methanethiol producing bacteria(MPB) were enriched and isolated from agricultural soils in a modified basal medium containing methionine(Met) as the sole carbon source.The isolates were identified as Bacillus sp.WH-R1, WH-R2, and WH-R3; Arthrobacter sp.SZLB-W3; and Delftia sp.CHZG-R4 based on cell morphology, physiological and biochemical characteristics, and 16 S r RNA sequence analysis.Delftia sp.CHZG-R4 was identified as a novel strain producing MT using Met as a precursor, and it had the most active MT-producing potential, with the production of MT being 21.8 μg at 30℃ and pH 7.0.Optimal MT production was observed at 35℃ and pH6.0, with 51.3% of sulfur content in Met being converted into MT.Under these conditions, MT production changed according to the supply of both carbon and nitrogen sources.The addition of 2 g L^(-1) each of starch, sucrose, urea, and potassium nitrate promoted MT production by more than 10%, whereas addition of 2 g L^(-1) each of ammonia sulfate and peptone decreased MT production by16% and 87%, respectively.This is the first study to report MT production by Delftia sp.CHZG-R4, providing useful information for the microbial mechanism of MT production from agricultural soils.Our findings also contribute to improving our knowledge of the function of Delftia sp.CHZG-R4.
基金Practical support of this work by University of Zanjan and Institute for Advanced Studies in Basic Sciences (IASBS) research councils is acknowledgedsupported in part by the Iranian National Science Foundation (INSF) under grant No.90001029
文摘The complexation of Pb^（2＋）by diallyl disulfide（DADS）, dimethyl disulfide（DMDS） and diallyl sulfide（DAS）has been studied by differential pulse voltammetry. Stability constants,（log b）, of the 1：1（PbL） and 1：2（PbL_2） complexes, where L = ligand, were found to be in the range of ca. 3.8-4.2 and 9.4-10.2,respectively. Complex formation is accompanied with a significant decrease in the peak current and the shift of the Pb2＋/Pb half-wave potential to a higher one upon the addition of the sulfur containing ligands（L）. The formation of 1：1 and 1：2 complexes, i.e., PbL^（2＋）and PbL_2^（2＋）was observed in the case of the three ligands. The consecutive formation constants of labile lead complexes with DADS, DMDS, and DAS were determined at 298 K by the method of De Ford and Hume. Apparently due to the large size of the lead ion,steric hindrance caused by the greater steric bulk of DADS compared to that of DMDS have little or no effects on the formation constants, so that very similar values were obtained in the case of the two ligands. Also, the possible participation of C=C double bonds in coordination with the metal center in the case of DADS appears to compensate for the steric effects caused by the larger size of this ligand. In agreement with the Jorgensen principle of symbiosis, the second formation constants were found to be approximately six orders of magnitude greater than the first ones.
文摘“High nutrient, low chlorophyll (HNLC)” regions were created by locking iron into sedimentary iron sulfides with hydrogen sulfide available from volcanic eruptions in surrounding oceans. Appropriate locations and deployment methods for the iron fertilization were far from volcanoes, earthquakes and boundaries of tectonic plates to reduce the chance of iron-locking by volcanic sulfur compounds. The appropriate locations for the large-scale iron fertilization are proposed as Shag Rocks in South Georgia and the Bransfield Strait in Drake Passage in the Southern Ocean due to their high momentum flux causing efficient iron deployment. The iron (Fe) replete compounds, consisting of natural clay, volcanic ash, agar, N<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">-fixing mucilaginous cyanobacteria, carbon black, biodegradable plastic foamed polylactic acid, fine wood chip, and iron-reducing marine bacterium, are deployed in the ocean to stay within a surface depth of 100<span style="font-family:""> <span style="font-size:12px;font-family:Verdana;"><span style="font-size:12px;font-family:Verdana;"><span style="font-family:Verdana;font-size:12px;">m for phytoplankton digestion. The deployment method of Fe-replete composite with a duration of at least several years for the successful iron fertilization, is configured to be on the streamline of the Antarctic Circumpolar Current (ACC). This will result in high momentum flux for its efficient dispersion on the ocean surface where diatom, copepods, krill and humpback whale stay together (~100<span style="font-family:""> <span style="font-family:""><span style="font-size:12px;font-family:Verdana;">m). Humpback whales are proposed as a biomarker for the successful iron fertilization in large-scale since humpback whales feed on krill, which in turn feed on cockpods and diatoms. The successful large-scale iron fertilization may be indicated by the return of the humpback whales if they could not be found for a long period before the iron fertilization. On-line monitoring for the successful iron fertilization focuses on the simultaneous changes of the following two groups;the increase concentration group (chlorophyll, O<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">, Dissolved Oxygen (DO), Di Methyl Sulfide (DMS)) and the decrease concentration group (nitrate, phosphate, silicate, CO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">, Dissolved CO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;"> (DCO<sub><span style="font-size:12px;font-family:Verdana;">2</sub><span style="font-size:12px;font-family:Verdana;">)). The monitoring of chlorophyll-<span style="font-size:12px;font-family:Verdana;">a<span style="font-size:12px;font-family:Verdana;">, nitrate phosphate, and silicate concentrations after deploying the Fe-replete complex is carried out throughout the day and night for the accurate measurement of algal blooms.
