Spectroscopic tools for remote sensing of greenhouse gases CH<Subscript>4</Subscript>, CF<Subscript>4</Subscript> and SF<Subscript>6</Subscript>

Highly symmetrical molecules such as CH₄, CF₄ or SF₆ are known to be atmospheric pollutants and greenhouse gases. High-resolution spectroscopy in the infrared is particularly suitable for the monitoring of gas concentration and radiative transfers in the earth's atmosphere. This technique requires extensive theoretical studies for the modeling of the spectra of such molecules (positions, intensities and shapes of absorption lines). Here, we have developed powerful tools for the analysis and the simulation of absorption spectra of highly symmetrical molecules. These tools have been implemented in the spherical top data system (STDS) and highly-spherical top data system (HTDS) software available at http://www.u-bourgogne.fr/LPUB/shTDS.html. They include a compilation of modeled data obtained during the last 20 years. An overview of our latest results in this domain will be presented. Electronic Publication     

Extraction of Co,Ni, Cu,Zn and Cd ions using 2-aminophenylaminopropylpolysiloxane

Insoluble porous solid functionalized ligand system bearing 2-aminophenylaminopropyl chelating ligand of the general formula P–(CH₂)₃NH–(C₆H₄)–NH₂ was prepared via the sol–gel process, where P represents [Si–O] _n polysiloxane network. First, the 2-aminophenylaminopropylsilane agent was prepared by substitution reaction between 3-chloropropyltrimethoxysilane and 1,2-phenylenediamine, followed by hydrolytic polycondensation between 2-aminophenylaminopropylsilane agent and tetraethylorthosilicate(TEOS). The immobilized 2-aminophenylaminopropylpolysiloxane P–(CH₂)₃NH–(C₆H₄)–NH₂(P–AphA) was characterized by ¹³C NMR, XPS, and FTIR. The results showed that 1,2-phenylenediamine groups were introduced onto polysiloxane network. The functionalized ligand system exhibits 90–100% metal uptake capacity for all metal ions except Cd²⁺. The elemental analysis data and the metal uptake capacities of the immobilized ligand system suggest that over than 90% ligand sites were involved in coordination with metal ions except that of cadmium forming 1:1 metal to ligand ratio complexes.     

Spectroscopic studies and biological evaluation of some transition metal complexes of a novel Schiff base ligands derived from 5-arylazo-salicyladehyde and o-amino phenol

Synthesis and characterization of Cu(II), Ni(II), and Zn(II) Schiff bases complexes resulted from the condensation of salicylaldehyde derivatives with o-amino phenol were discussed using elemental analysis (carbon, hydrogen, and nitrogen), molar conductance, magnetic measurements, mass spectra, and electronic spectra. The essential bands of infrared, ¹HNMR, and UV-Vis spectra as well as thermogravimetric analysis corresponding to the active groups within the three ligands and their complexes were interpreted. The dehydration and decomposition processes of the [Cu(H₂L₁)(H₂O)](OAc)₂, [Ni(H₂L₁)(H₂O)]SO₄ · H₂O, [Zn(H₂L₁)(H₂O)]SO₄ · H₂O, [Cu(H₂L₂)(H₂O)](OAc)₂, [Ni(H₂L₂)(H₂O)]SO₄ · H₂O, [Zn(H₂L₂)(H₂O)]SO₄ · 2H₂O, [Cu(H₂L₃)(H₂O)](OAc)₂ · H₂O, [Ni(H₂L₃)(H₂O)]SO₄ · 2H₂O, [Zn(H₂L₃)(H₂O)]SO₄ complexes were studied thermodynamically using the integral method applying the Coats–Redfern and Horowitz–Metzger equations and the thermodynamic parameters were calculated. It was found from the elemental analysis and the thermal studies, that the ligand behaves as tridentate ligand forming chelates with 1 : 1 (metal : ligand) stoichiometrically. The molar conductance measurements of the complexes in dimethyl sulfoxide solvent indicate that the complexes have an electrolytic nature. The biological activities of the three ligands in comparison with metal(II) complexes were studied against different Gram positive and Gram negative bacteria.     

Photochemical reaction of nitro-polycyclic aromatic hydrocarbons: effect by solvent and structure

Photochemical degradation of 1-nitropyrene, 2-nitrofluorene, 2,7-dinitrofluorene, 6-nitrochrysene, 3-nitrofluoranthene, 5-nitroacenaphthene, and 9-nitroanthracene was examined in CHCl₃, CH₂Cl₂, DMF, DMF/H₂O (80/20), CH₃CN, or CH₃CN/H₂O (80/20). The degradation mostly follows the first order kinetics; but a few follow second order kinetics or undergo self-catalysis. The photodegradation rates follow the order: CHCl₃ > CH₂Cl₂ > DMF > DMF/H₂O > CH₃CN > CH₃CN/H₂O. DMF is an exceptional solvent because three of the seven compounds undergo self-catalytic reaction. 9-Nitroanthracene, which has a perpendicular nitro group, is the fastest, while the more compact 1-nitropyrene and 3-nitrofluoranthene are the slowest degrading compounds.     

Efficient adsorption of carbon dioxide and methane on activated carbon prepared from glycerol with potassium acetate

In the context of global warming and the energy crisis, emissions to the atmosphere of greenhouse gases such as carbon dioxide (CO₂) and methane (CH₄) should be reduced, and biomethane from landfill biogas should be recycled. For this, there is a need for affordable technologies to capture carbon dioxide, such as adsorption of biogas on activated carbon produced from industrial wastes. Here we converted glycerol, a largely available by-product from biodiesel production, into activated carbon with the first use of potassium acetate as an activating agent. We studied adsorption of CO₂ and CH₄ on activated carbon. The results show that activated carbon adsorb CO₂ up to 20% activated carbon weight at 250 kPa, and 9% at atmospheric pressure. This is explained by high specific surface areas up to 1115 m²g⁻¹. Moreover, selectivity values up to 10.6 are observed for the separation of CO₂/CH₄. We also found that the equivalent CO₂ emissions from activated carbon synthesis are easily neutralized by their use, even in a small biogas production unit.

     

Photosynthetic utilization of CO2(aq) and HCO 3 - in Thalassia testudinum (Hydrocharitaceae)

The effects of total dissolved inorganic carbon (DIC), free carbon dioxide [CO_2(aq)], and bicarbonate (HCO ₃ ^- ) concentrations on net photosynthetic oxygen evolution of the marine angiosperm Thalassia testudinum Banks ex König collected from Biscayne Bay (1988) and from Tampa Bay (1990), Florida, USA, were examined. Rates of photosynthesis declined by 85% from pH 7.25 to 8.75 in buffered seawater media with constant DIC concentration (2.20 mM), suggesting a strong influence of CO_2(aq) concentration. A plateau in the pH-response curve between pH 7.75 and 8.50 indicated possible utilization of HCO ₃ ^- . Responses of photosynthesis measured in buffered seawater media of varying DIC concentrations (0.75 to 13.17 mM) and pH (7.8 to 8.61) demonstrated that photosynthesis is rate-limited at ambient DIC levels. Photosynthesis increased in media with increasing HCO ₃ ^- concentrations but near-constant CO_2(aq) levels, confirming HCO ₃ ^- assimilation. Calculated half-saturation constants (K _s )for CO_2(aq) and HCO ₃ ^- indicated a high affinity for the former [K _s (CO₂)=3 to 18 M] and a much lower affinity for the latter [K _s (HCO ₃ ^- )=1.22 to 8.88 mM]. Calculated V _max values for HCO ₃ ^- were generally higher than those for CO_2(aq), suggesting relatively efficient HCO ₃ ^- utilization, despite the apparent low affinity for this carbon form.     

Evaluation of greenhouse gas emissions from wetland and agriculture ecosystems in Sanjiang Plain

Carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) are important greenhouse gases (GHGs). The objective of this study is to quantify the aggregate GHG (CH₄, N₂O and CO₂) emissions and estimate economic losses of three ecosystems (marsh, paddy field and upland) in the Sanjiang Plain, excluding the Muling-Xiangkai Plain, south of Wanda Mountain. The results indicate the economic losses from GHG emissions of marshes were from 6.40 to 7.75?×?10⁹ CNY (Chinese Yuan), those of paddy fields were from 1.41 to 3.20?×?10⁹ CNY; and from uplands were from 0.26 to 0.49?×?10⁹ CNY. Using linear trend analysis, the economic losses through GHG emissions of marshes fell between 1982 and 2005, but those from paddy fields and uplands increased. In our study, the sequence in magnitude of the economic losses from GHG emissions was: marshes > paddy fields > uplands. In fact, the economic value of GHG emissions was negative because of these adverse impacts on the environment. This article could provide a reference for calculation of GHG exchange. The results suggest that improvement of fertiliser use efficiency for more precise agricultural management and returning straw to cropland could mitigate GHG emissions and would help to achieve sustainable development.     

Pilot-scale studies of domestic wastewater treatment by typical constructed wetlands and their greenhouse gas emissions

Three typical constructed wetlands (CWs) including Vertical Flow (VF), Free Water Surface (FWS), and Subsurface Flow (SF), and combined VF-SF-FWS constructed wetlands were investigated for the treatment of domestic wastewater with low C/N ratio. The performance of nutrient removal and the characteristics of greenhouse gas emissions, such as CH₄ and N₂O, from these CWs were compared. The results indicated that the four types of CWs had high removal efficiencies for organic matter and suspended solid (SS). The combined wetland also showed a comparatively good performance for nitrogen and phosphorus removal, and the removal efficiencies for total nitrogen (TN) and total phosphorus (TP) were 81.3% and 84.5%, respectively. The combined CWs had a comparative lower global warming potential. The FWS CW had the highest tendency to emit CH₄ and led to a higher global warming potential among the four types of CWs, which was about 586 mg CO₂/m²·h.     

Ionic liquids for the inhibition of gas hydrates. A review

The formation of gas hydrates is a major issue during the operation of oil and gas pipelines, because gas hydrates cause plugging, thereby disrupting the normal oil and gas flows. A solution is to inject gas hydrate inhibitors such as ionic liquids. Contrary to classical inhibitors, ionic liquids act both as thermodynamic inhibitors and hydrate inhibitors, and as anti-agglomerates. Imidazolium-based ionic liquids have been found efficient for the inhibition of CO₂ and CH₄ hydrates. For CO₂ gas hydrates, N-ethyl-N-methylmorpholinium bromide showed an average depression temperature of 1.72 K at 10 wt% concentration. The induction time of 1-ethyl-3-methyl imidazolium bromide is 36.3 h for CO₂ hydrates at 1 wt% concentration. For CH₄ hydrates, 1-ethyl-3-methyl-imidazolium chloride showed average depression temperature of 4.80 K at 40 wt%. For mixed gas hydrates of CO₂ and CH₄, only quaternary ammonium salts have been studied. Tetramethyl ammonium hydroxide shifted the hydrate liquid vapour equilibrium to 1.56 K at 10 wt%, while tetrabutylammonium hydroxide showed an induction time of 0.74 h at 1 wt% concentration.

     

Fluorescence studies of dye displacement from DNA by chromium(III) complexes: Evidence for cation induced DNA condensations

The interactions of 10 different chromium(III) complexes with isolated calf thymus DNA have been analysed by studying the electronic and fluoresence spectra of intercalated ethidiumbromide. Triply charged cationic complexes including: [Cr(urea)₆]Cl₃.3H₂O, [Cr(1,10‐phenanthroline)₃](ClO₄)₃.2H₂O, [Cr(2,2'‐bipyridyl)₃] (ClO₄)₃.2H₂O, [Cr(ethylendiamine)₃]Cl₃.3.5H₂O and [Cr(NH₃)₆](NO₃)₃ displaced the dye from DNA. Similar effects were observed in experiments using the non‐intercalating dye bisbenzimidazole ("Hoechst 33258"). However, singly charged cationic, anionic and uncharged chromium(III) complexes such as: cis‐[Cr(1,10‐phenanthroline)₂Cl₂]Cl.2H₂O, cis‐[Cr(2,2'‐bipyridyl)₂Cl₂]Cl.2H₂O, [Cr(glutathione)₂]Na₂, [Cr(cysteine)₂]Na.2H₂O and [Cr(glycine)₃] were unable to displace both ethidiumbromide and bisbenzimidazole from DNA. There was no evidence for the formation of co‐ordinate bonds between chromium(III) and DNA for any of the above complexes. The charge and type of ligand are important in controlling the interaction of chromium(III) with isolated DNA in vitro. Our findings indicate that the outer sphere interaction of a chromium(III) complex with DNA is weak and unlikely to be the mechanism by which chromate causes DNA impairments in vivo and in vitro.     

Niedere pilze als testorganismen für schadstoffe in meer- und brackwasser die wirkung von schwermetallverbindungen und phenol auf Thraustochytrium striatum

Three test-series were applied, which differed in regard to the basal medium (natural or artificial sea water, salinity level, addition of detergent); the culture conditions (primary cultures, subcultures, back-inoculations into basal medium without toxic metals); the criterion employed (zoospore activity, sporangia development, or dry weight of Thraustochytrium striatum Schneider). The temperature applied was 18° to 20°C. The sea water-pollen-method (MWP) proved to be the most suitable: it is simple and more sensitive than the other tests; subcultures and back-inoculations are possible without much additional work; conditions simulate nature; first results are available after 3 to 4 days. The SMS-method (enriched natural sea water of different salinities) provides additional information on salinity effects. Nine substances have been tested: (CH₃COO)₃Hg, HgCl₂, CdCl₂·H₂O, ZnSO₄ ·7H₂O, NiSO₄·7H₂O, CuSO₄·5H₂O, CoCl₂·6H₂O, MnCl₂ ·4H₂O, and phenol. In regard to their toxicity these substances can be divided into 2 groups: Hg- and Cd-salts inhibit development down to greater dilutions than the remainder; Zn and Ni seem to yield intermediate effects. Salinity modifies the toxic effects of the test substances. In higher salinities, comparable concentrations of test substances reveal stronger inhibitory effects than in lower salinities. Detergents may augment the toxic effects, at least of CuSO₄. The marine lower fungus T. striatum is a useful organism for testing biological consequences of water pollutants.     

High CO<Subscript>2</Subscript> absorption of <Emphasis Type="Italic">O</Emphasis>-carboxymethylchitosan synthesised from chitosan

CO₂ absorption by liquid-containing amines to form carbamate and bicarbonates is an effective method of CO₂ mitigation from industrial exhausts, but this process is expensive and requires large quantities of amines. Here we modified chitosan, a naturally occurring biopolymer containing NH₂ functions, to use it for CO₂ absorption in aqueous media. Chitosan was dispersed in 40% aqueous NaOH solution then treated with monochloroacetic acid dissolved in isopropanol, to yield O-carboxymethylchitosan. Results show that the CO₂ absorption capacity of O-carboxymethylchitosan is 0.508 g/g, which is higher than the capacity of conventional amines such as 1-aminoamine, 2-methylpropanolamine and methyldiethanol amine, but lower than the capacity of monoethanolamine. A cyclic study showed that O-carboxymethylchitosan is a stable component for CO₂ absorption and regeneration.     

Heavy-metal adsorption by non-living biomass

The adsorption of some heavy metals onto the walls of harvested, washed, and dried non-living biomass cells of different Pseudomonas strains was studied at optimum experimental conditions using a simplified single component system. The Langmuir adsorption model was found to be a suitable approach to describe the system via multi-step processes. Isotherms measured at 30.0°C and pH 5.5 with [M]_total?=?10–100 mM for tight, reversible Cr⁶⁺(aq), Ni²⁺(aq), Cu²⁺(aq) and Cd²⁺(aq) binding by the cell walls of the investigated biomass fit the Langmuir model and give the pH-independent stoichiometric site capacities ν _i and equilibrium constants K _i for metal binding at specific biomass sites i?=?A, B, C, and D. Tight binding sites A, B, and D of the non-living biomass are occupied by Cr^VI, sites A and C by Ni^II, sites A and D by Cd^II, and only site B by Cu^II. It is concluded that ν _i is a stoichiometric parameter that is independent of the magnitude of K _i for binding site i and that the studied heavy metals selectively and tightly bind at different biomass sites.     

密度泛函理论方法研究铝-麦芽酚配合物的形态结构与水交换反应

在B3LYP/6-311+G(d,p)基组水平下采用密度泛函理论方法系统开展了以下工作:(1)优化得到1∶1、1∶2和1∶3铝-麦芽酚配合物10种可能构型的静态结构、NPA电荷以及能量参数,计算得到Al(ma)3配合物4种异构体的核磁共振、紫外和红外等光谱学数据并与文献实验值比较,证明本文采用的计算方法和模型适用于铝-麦芽酚体系的研究;(2)模拟1∶1和1∶2铝-麦芽酚配合物9种可能位点的水交换反应,其中3个位点计算得到的水交换反应速率对数log kex(s-1)分别为2.4(Al(ma)(H2O)2+4(cis to ma))、2.6(cis-Al(ma)2(H2O)+2(I))和3.0(trans-Al(ma)2(H2O)+2(I)),与实验值2.5(Al(ma)2+)和3.3(Al(ma)+2)相符,说明相应位点为反应活性位点;(3)探讨铝-麦芽酚配合物毒性与其形态结构之间的相关机制。     

Mass spectral studies of 6‐n‐propyl‐2‐thiouracil,its oxygen,selenium and fluorinated congeners∗

The electron ionization mass spectra of the clinically used antithyroid agent 6‐n‐propyl‐2‐thiouracil (la), its minor metabolite, 6‐n‐propyluracil (lb) and their synthetic selenium and fluorinated analogs (1c and d) have been examined. The fragmentation pattern of these thiouracil and selenouracil studied bear strong similarities with those previously derived from a study of uracil analogs. Thus, the first step in the fragmentation is a retro Diel‐Alder decomposition with the loss of HCNX (X=O, S or Se) and the production of an ion radical which undergoes further fragmentation pathways which are discussed. 6‐n‐Propyl‐2‐selenouracil (1c) did show more complicated spectra due to the six natural isotopic abundance exhibited by the selenium atom. While the fluorinated analogs (1d) did substantiate the fact that the fragmentation pattern of these derivatives proceed through fragmentation between C₂ and N₃ bond since this produces the more resonance stabilized ion.     

Availability of colloidal ferric oxides to coastal marine phytoplankton

Cell growth of a coastal marine diatom, Phaeodactylum tricornutum (stock cultures), and two red tide marine flagellates, Heterosigma akashiwo and Gymnodinium mikimotoi (stock cultures), in the presence of soluble chelated Fe(III)-EDTA (1:2) and of four different phases of ferric oxide colloids were experimentally measured in culture experiments at 20°C under 3000 lux fluorescent light. Soluble Fe(III)-EDTA induced the maximal growth rates and cell yields. The short-term uptake rate of iron by H. akashiwo in Fe(III)-EDTA medium was about eight times faster than that in solid amorphous hydrous ferric oxide (Fe₂O₃·xH₂O) medium. In culture experiments supplied with four different ferric oxide forms, the orders of cell yields are amorphous hydrous ferric oxide>-FeOOH (lepidocrocite)>Fe₅O₇(OH)·4H₂O (hydrated ferric oxyhydroxide polymer >-FeOOH (goethite). The specific growth rates () at logarithmic growth phase in Fe(III)-EDTA, amorphous hydrous ferric oxide and -FeOOH media were significantly greater than those in Fe₅O₇ (OH)·4H₂O and -FeOOH media. The thermodynamically stable forms such as Fe₅O₇(OH)·4H₂O and -FeOOH supported a little or no phytoplankton growth. The iron solublities and/or proton-promoted iron dissolution rates of these colloidal ferric oxides in seawater at 20°C were determined by simple filtration techniques involving -activity measurements of ⁵⁹Fe. The orders of solubilities and estimated dissolution rate constants of these ferric oxides in seawater were consistent with that of cell yields in the culture experiments. These results suggest that the availability of colloidal iron to provide a source of iron for phytoplankton is related to the thermodynamic stability and kinetic lability of the colloidal ferric oxide phases, which probably control the uptake rate of iron by phytoplankton.     

Use of the “Acetylene blockage” technique for assaying denitrification in a salt marsh

The acetylene blockage technique was evaluated for measurement of denitrification in salt-marsh sediments (near Halifax, Nova Scotia, Canada). N₂O in the gas phase of closed Spartina alterniflora marsh-sediment systems was analyzed with use of a thermal conductivity gas chromatograph sensitive to approximately 0.1 nmoles ml^-1 gas. No N₂O was detected for unfertilized sediment samples taken through the growing season and incubated in sealed buckets with 10% C₂H₂. For sediment samples amended with nitrate and for enrichments, initial rates of N₂O evolution were higher in the presence of 10% C₂H₂ than in the absence of C₂H₂, but after longterm incubation N₂O was consumed in some samples containing C₂H₂ as well as in samples without C₂H₂. In addition, total gaseous nitrogen (N₂ and N₂O) production in the absence of C₂H₂ was higher than in the presence of C₂H₂. Acetylene appears to be an inconsistent inhibitor of N₂O reduction in salt-marsh sediments. The usefulness of the acetylene-denitrification technique in this habitat is, therefore, questionable.     

Effect of biochar addition on short-term N<Subscript>2</Subscript>O and CO<Subscript>2</Subscript> emissions during repeated drying and wetting of an anthropogenic alluvial soil

Agricultural soils are an important source of greenhouse gases (GHG). Biochar application to such soils has the potential of mitigating global anthropogenic GHG emissions. Under irrigation, the topsoils in arid regions experience repeated drying and wetting during the crop growing season. Biochar incorporation into these soils would change the soil microbial environment and hence affect GHG emissions. Little information, however, is available regarding the effect of biochar addition on carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from agricultural soils undergoing repeated drying and wetting. Here, we report the results of a 49-day aerobic incubation experiment, incorporating biochar into an anthropogenic alluvial soil in an arid region of Xinjiang Province, China, and measuring CO₂ and N₂O emissions. Under both drying–wetting and constantly moist conditions, biochar amendment significantly increased cumulative CO₂ emission. At the same time, there was a significant reduction (up to ~20 %) in cumulative N₂O emission, indicating that the addition of biochar to irrigated agricultural soils may effectively slow down global warming in arid regions of China.     

Reduction of CO2 emission by optimally tracking a pre-defined target

The recent global financial crisis has highlighted the need for balanced and efficient investments in the reduction of the greenhouse effect caused by emissions of CO₂ on a global scale. In a previous paper, the authors proposed a mathematical model describing the dynamic relation of CO₂ emission with investment in reforestation and clean technology. An efficient allocation of resources to reduce the greenhouse effect has also been proposed. Here, this model is used to provide estimates of the investments needed in land reforestation and in the adoption of clean technologies for an optimum emission and abatement of CO₂, for the period of 1996–2014. The required investments are computed to minimize deviations with respect to the emission targets proposed in the Kyoto Protocol for European Countries. The emission target can be achieved by 2014 with investments in reforestation peaking in 2004, and a reduction of the expected GDP of 42%, relative to 2006. Investments in clean technology should increase between 2008 and 2010 with maximum transfer figures around 70 million American dollars. Total (cumulative) costs are, however, relatively high depending on the price of carbon abatement and the rate at which the expected CO₂ concentration in the atmosphere should be reduced. Results highlight the advantages for policy makers to be able to manage investments in climate policy more efficiently, controlling optimum transfers based on a portfolio of actions that tracks a pre-defined CO₂ concentration target.