What fraction of the organic carbon in sacoglossans is obtained from photosynthesis by kleptoplastids? An investigation using the natural abundance of stable carbon isotopes

any sacoglossans (opisthobranch gastropods) have the potential for carbon acquisition from photosynthesis by plastids sequestered from their macroalgal food as well as by ingestion, digestion and assimilation of the organic carbon derived from the alga. A new method for obtaining a minimum estimate of the fraction of sacoglossan carbon supplied from photosynthesis by kleptoplastids is suggested, based on the mass balance of stable carbon isotopes at the natural abundance level. The method involves comparison of ¹³C/¹²C ratios in sacoglossans with those of the algae on which they are found. Differences in ratios between alga and sacoglossan are used to give a minimum estimate of carbon acquisition by kleptoplasty, granted assumptions about the range of ¹³C/¹²C fractionation values which can occur for marine photolithotrophs. The new method is applied to several green (ulvophycean) alga–sacoglossan associations from Rottnest Island, Western Australia, and the values compared with those obtained previously by other means. The method suggests values of up to 0.6 of the total carbon input to the sacoglossans from photosynthesis by their kleptoplastids. To improve the estimates of the minimum role of kleptoplastidy in the carbon nutrition of sacoglossans, further information is needed: (1) on the fidelity of a given sacoglossan to a given algal individual (or species), (2) on the ¹³C/¹²C ratio of the part of the alga ingested by the sacoglossan, and (3) on the allocation of dietary organic carbon and of kleptoplastidic photosynthate to carbon lost in respiration, mucopolysaccharide production and gametes (and hence not sampled with the animal). Received: 24 November 1999 / Accepted: 20 October 2000     

Nanoconfinement engineering for enchanced adsorption of carbon materials,metal–organic frameworks,mesoporous silica,MXenes and porous organic polymers: a review

In material synthesis, nanoconfinement acts both as a physical reactor to tune the shape and size of nanomaterials, and as a chemical microenvironment for the nucleation and growth of nanoconfined substances, resulting in unique material properties. This nanoconfinement effect has been extensively applied to synthesize materials for hydrogen storage, catalysis and separation for environmental protection. Here, we review methods to construct nanoconfined space in carbon materials, metal–organic frameworks, mesoporous silica, porous organic polymers and MXenes, a class of two-dimensional inorganic compounds. We discuss nanoconfinement for enhanced adsorption with focus on covering size and dispersion, crystallization and stability, confined water and coordination.

     

Generation of new carbon–carbon and carbon–heteroatom bonds mediated by agro-waste extracts: a review

Agro-waste extracts are considered green solvents since they are easy to handle, readily accessible from natural waste feedstock, biodegradable and recyclable. Therefore, the employment of these extracts in reaction media has emerged as the most useful and eco-friendly alternative in modern organic chemistry. Here, we review recent developments for the generation of new carbon–carbon and carbon–heteroatom bonds mediated by agro-waste extracts. We show that these aqueous extracts have great applicability in several transformations, including condensations, oxidations, multicomponent and coupling reactions. The challenges and advantages on the use of water of agro-waste extracts in synthetic methodologies is also detail.

     

Soil organic matter chemistry. Part 1. Characterization of several humic preparations by proton and carbon‐13 nuclear magnetic resonance spectroscopy

Both laboratory and commercial preparations of humic substances (HSs) such as fulvic acids and humic acids along with HC1‐HF preparation of Manitoba peat soil organic matter were characterized using Fourier Transformation (FT) proton (¹H) and carbon‐13 (¹³C) nuclear magnetic resonance (NMR) spectroscopy. All the samples were dissolved in a solution of 0.4 N NaOD in D₂O. In the case of ‘H‐NMR spectroscopy, all the investigated humic samples displayed resonance absorption peaks in the region of 1–4 ppm indicating the likely presence of aliphatic protons in the preparations. However, with the exception of one fulvic acid preparation (extracted from Manitoba Carrol clay‐loam soil with 0.5 N NaOH), ¹H‐NMR spectra of all other samples provided evidence for strong aromatic character. The aliphatic and aromatic characteristics of such samples of HSs were further confirmed with the aid of ¹³C‐NMR spectra.     

Variation in soil organic carbon mineralization and microbial community structure induced by the conversion from double rice fields to drained fields北大核心CSCD

Land use conversion is an important factor influencing the carbon gas exchange between land and atmosphere. The effect of land use conversion on soil organic carbon mineralization and microbial function is important for soil organic carbon sequestration and stability. This research studied the effects of land use conversion on soil chemical properties, organic carbon mineralization and microbial community structure after two years of conversion from double rice cropping (RR) to maize-maize (MM) and soybean-peanut (SP) double cropping systems in southern China. The results showed that soil pH significantly decreased by 0.50 (MM) and 0.52 (SP, P = 0.002), and dissolved organic carbon significantly increased by 23%- 35% (P = 0.016). No significant difference was found in soil organic carbon mineralization rate with the land use conversion, though the accumulated mineralization decreased after 13 days of incubation (P = 0.019). Land use conversion from paddy to upland significantly changed soil microbial community structure. The total PLFAs, bacterial, gram-positive bacterial (G+), gram-negative bacterial (G-) and actinomycetic PLFAs decreased significantly (P < 0.05), the ratio of fungal PLFAs to bacterial PLFAs (F/B) increased significantly (P = 0.006). But no significant differences in microbial groups were found between MM and SP. The accumulated mineralization at the beginning period of the incubation were significantly positively correlated with soil actinomycetic PLFAs (P = 0.034). After 13 days of incubation, soil F/B showed a positive correlation with the accumulated mineralization (P = 0.004). However, soil microbial community structure(P = 0.014)and total PLFAs(P = 0.033)showed a positive correlation with the accumulated mineralization after 108 days of incubation. Our results indicated that after conversion from paddy soils to drained soils, soil pH and total nitrogen are the key factors regulating the variations in soil microbial community structure and biomass, and then influencing soil organic carbon mineralization.     

Quantitative structure‐activity relationships of hydrophobic organic chemicals 1

Quantitative structure‐activity relationships of hydrophobic organic chemicals were studied based on equations we established. Results showed that observed toxicity of hydrophobic organic chemicals were correlated to two physical‐chemical parameters: reaction equilibrium constant of target molecule‐organic chemical; octanol/water partition coefficient. Regression results showed that the molecular connectivity index of first‐order was an ideal parameter instead of the equilibrium constant. Good relationships between toxicity data and the two parameters were found for three aquatic organisms with a wide range of chemicals.     

Reduction of carbon dioxide into tetraiodomethane at 1?atm

We here report that by using electronegative gas of iodine and CO₂ under negative corona discharge, tetraiodomethane could be synthesized at 70?°C and 1?atm without any catalyst, despite thermodynamically infeasible at ambience without electron discharge. The conversion of carbon dioxide reached 88.71?% at a gas flow rate of 0.06?L/min and a discharge frequency of 9.608?kHz. The anion-involved CO₂ reduction process could be implemented efficiently under mild conditions, avoiding high temperature and high pressure.     

Metal–organic frameworks for active food packaging. A review

Environmental Chemistry Letters - Food wastage is a major concern for sustainable health and agriculture. To reduce food waste, classical preservation techniques such as drying, pasteurization,...     

Metal binding capacity of soft acid,organic‐rich waters

Organic carbon from one stream and two ponds in South Carolina was fractionated into five nominal molecular diameter fractions by ultrafiltration. The concentrations associated with and binding capacity for Ca, Cd, Cu and Pb were determined for each fraction. The distribution of organic carbon among ultrafilter fractions varied from water to water, with the largest percentage occurring in the smaller fractions. Calcium was associated with each of the fractions isolated from each of the three waters, indicating Ca is bound to organics in all fractions, however, more than 99% of the Ca which passed the smallest ultrafilter was removed by cationic exchange resin. Each fraction bound more Ca than Cd, Cu or Pb except in a few cases where Pb binding was greater. All of the organic fractions had their Ca++ binding sites saturated. Calcium was not an effective competitive ion against Cd, Cu or Pb for organic binding sites. The total Cu binding capacity was less than that of Ca or Pb but similar to that of Cd. Naturally occurring organics bound more Pb than Cd or Cu but less than Ca. Saturation of Cu binding sites was less than 20% in most ultrafilter fractions except that with a nominal molecular weight of between 10,000 and 300,000 where the percent of saturation was as much as 60%. Approximately 50% of the Cu was removed onto anionic exchange resin in two waters while more than 90% was removed from water with a high organic content. Percent saturation of Cd and Pb binding sites ranged from 0.091% to 5.4% and 0.059% to 1.5%, respectively. All ions tested effectively competed with Cd, Cu or Pb for some but not all binding sites, indicating that organic binding sites were heterogeneous. A generalized order of metal‐organic stabilities based on competition for binding sites is Al>Cd>Pb>Cu>Ni = Mg=Zn = Mn>Ca. Both Cd+2 and Al+3 effectively out competed Pb++ and Cd and Pb out competed Cu for most organic binding sites.     

Does the EU ETS cause carbon leakage in European manufacturing?

Carbon leakage is of interest in both academic and policy debates about the effectiveness of unilateral climate policy, especially in Europe, where the EU Emissions Trading System (EU ETS) affects many traded sectors. We review how the literature identifies leakage and the pollution haven effect. We then evaluate whether EU ETS emission costs caused carbon leakage in European manufacturing, using trade flows in embodied carbon and value from the Global Trade Analysis Project (GTAP). We find no evidence that the EU ETS caused carbon leakage.     

Aerogels and metal–organic frameworks for environmental remediation and energy production

Environmental pollution and climate change are requiring new methods to clean pollutants and produce sustainable energy. Aerogels and metal organic frameworks are emerging as advanced porous materials with higher functionality, high surface area, high porosity and flexible chemistry. Aerogels are dried gels prepared using the sol–gel procedure, whereas metal organic frameworks are networks of organic ligands and metal ions connected by coordination bonds. Applications of aerogels include the removal of heavy metals, CO₂ capture and reduction, photodegradation of pollutants, air cleanup and water splitting. This article reviews the synthesis and types of aerogels and metal organic frameworks, and the application to pollutant removal, energy production including hydrogen, methane reforming, CO₂ conversion and NOx removal.     

Detection of organic contamination in sediments by double-shoot pyrolysis–GC/MS

Pyrolysis coupled with gas chromatography–mass spectrometry (Py–GC–MS) has been previously proved to be an appropriate tool for the screening of organic contaminants in sediments. In this work the double-shoot pyrolysis technique has been applied to assess the contamination degree of sediment samples from Castro Marim Natural Park (South Portugal) and the Ria of Huelva (SW Spain). Compounds released both by thermodesorption at sub-pyrolysis temperatures (250–280°C) and subsequent pyrolysis (300–500°C) revealed information on the origin of the sedimentary organic matter and the occurrence of organic contamination in the sediments. Thermal desorption was found to be effective in releasing organic contaminants from spiked samples. However, in real sediments samples, higher pyrolysis temperatures (>300°C) were necessary to detect the occurrence of organic contaminants. Particularly polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs) were detected in variable proportions in most sediment samples.     

Activated carbons and amine-modified materials for carbon dioxide capture — a review

Rapidly increasing concentration of CO₂ in the atmosphere has drawn more and more attention in recent years, and adsorption has been considered as an effective technology for CO₂ capture from the anthropogenic sources. In this paper, the attractive adsorbents including activated carbons and amine-modified materials were mainly reviewed and discussed with particular attention on progress in the adsorbent preparation and CO₂ adsorption capacity. Carbon materials can be prepared from different precursors including fossil fuels, biomass and resins using the carbonization-activation or only activation process, and activated carbons prepared by KOH activation with high CO₂ adsorbed amount were reviewed in the preparation, adsorption capacity as well as the relationship between the pore characteristics and CO₂ adsorption. For the amine-modified materials, the physical impregnation and chemical graft of polyethylenimine (PEI) on the different porous materials were introduced in terms of preparation method and adsorption performance as well as their advantages and disadvantages for CO₂ adsorption. In the last section, the issues and prospect of solid adsorbents for CO₂ adsorption were summarized, and it is expected that this review will be helpful for the fundamental studies and industrial applications of activated carbons and amine-modified adsorbents for CO₂ capture.     

Modified ��-cyclodextrins as prospective agents for improving water solubility of organic pesticides

The drawback of some organic pesticides is their low water solubility. Cyclodextrins are used as agents for improving pesticides water solubility. However, the stabilization of the crystalline lattice can reduces to a large extent the solubility of cyclodextrins, especially β-cyclodextrin. Here, searching for the water soluble β-cyclodextrin derivatives, a set of new “host” compounds were prepared by the reaction of β-cyclodextrin with methyl epoxycinnamate. The reactants ratio was varied in to study the substitution degree of the obtained derivatives. The structure was determined by the ¹H-NMR and FT IR spectra. The average degree of substitution was determined by integration of the corresponding NMR signals and by elemental analysis. The solubility of four selected pesticides: dimethoate, simazine, linuron and thiram, in water with and without addition of the new modified β-cyclodextrin was measured by ultraviolet spectrophotometry. Our results showed that the modified β-cyclodextrins significantly improve solubility of pesticides.     

What drives resident acceptance of personal carbon trading policy in China?

Environmental Geochemistry and Health - Personal carbon trading (PCT) policy has been considered as an innovative and radical environmental policy tool to achieve carbon neutrality in private...     

Do renewable energy policies reduce carbon emissions? On caps and inter-industry leakage

In a parsimonious two-sector general equilibrium model, we challenge the widely-held tenet that within a cap-and-trade system renewable energy policies have no effect on carbon emissions. If the cap does not capture all sectors, we demonstrate that variations of a renewable energy subsidy change aggregate carbon emissions through an inter-industry leakage effect. We decompose this effect into intuitively intelligible components that depend in natural ways on measurable elasticity parameters. Raising the subsidy always reduces emissions if funded by a lump-sum tax, reinforcing recent findings that tightening environmental regulation can cause negative leakage. However, if the subsidy is funded by a levy on electricity, it can increase emissions. These results provide a valuable basis for an informed design of renewable energy policies and an accurate assessment of their effectiveness. We highlight how a state-of-the-art statistic used by governments to gauge such effectiveness, “virtual emission reductions”, is biased, because inter-industrial leakage effects are not captured.     

Impacts of inter-sectoral trade on carbon emissions—a case of China in 2007

With the increase in international trade, more attention has been given to quantifying the impacts of international trade on energy use and carbon emissions. Input-output analysis is a suitable tool for assessing resources or pollutants embodied in trade and it has become a critical tool for performing such analysis. This study estimated the national and sectoral carbon emissions embodied in Chinese international trade using the latest available China input-output table of 2007. The results showed that a significant exporting behavior of embodied carbon emissions existed in China??s trade. Over 1/3 of the emissions in Chinese domestic production processes were generated for exports in 2007. The net balance of emissions embodied in exports and imports accounted for nearly 30% of China??s domestic emissions, which means that any policy made to increase the exports would result in a significant growth of China??s domestic emissions. Since over half of China??s export trade is processing trade, the re-exported emissions could not be overlooked; otherwise, it would hard to capture the actual emissions generated abroad to obtain China??s domestic consumption. The enlargement of export scale is a primary driven factor to the rapid growth of China??s exported emissions. It is necessary for China to adjust its economic and industrial structure to reduce the dependence of economic growth on the export trade. However, when adjusting industry structures or making policies on carbon emission reduction, it will be more reasonable to consider the relationship between production and consumption, rather than just focus on the emission values of sectors?? direct production, as a large part of carbon emissions emitted by the principal direct polluters were generated to obtain the products which were required by other sectors.     

Eventual saturation of the climate–carbon cycle feedback studied with a conceptual model

A saturation of climate–carbon cycle feedback was found earlier in the simulations with the IAP RAS climate model of intermediate complexity. Here, this eventual saturation is interpreted by using a conceptual linearised coupled model. It is shown that this saturation is due to weak, logarithmic, dependence of the carbon dioxide radiative forcing on its atmospheric concentration. This eventual saturation leads to the non-monotonic behaviour of climate–carbon cycle parameter f   in time. If the time scale of the atmospheric CO₂${\text{CO}}_2$ build up is _tp$t_{\text{p}}$ then, starting from an initial equilibrium, f   approaches maximum in time ?_tp$?t_{\text{p}}$. Afterwards, climate–carbon cycle parameter decreases and eventually tends to unity. The time scale of the latter decrease is _t1=(1−5)_tp$t_1=(1-5)t_{\text{p}}$. A dependence of _tm$t_{\text{m}}$ and _t1$t_1$ on governing parameters of the conceptual model is studied. It is argued that an eventual saturation of the climate–carbon cycle feedback is expected to occur also in the other integrations of sufficient length with coupled climate–carbon cycle models.