CO2 Release Research Articles

Effect of low pH on embryonic and larval traits in the estuarine semi-terrestrial crab Neohelice granulata

The decrease in the pH of the oceans is one of the consequences of the release of CO2 (carbon dioxide) into the atmosphere by human activities. In estuaries, the magnitude to which pH will change and how the organisms that inhabit these environments would be affected is today relatively poorly known. We evaluated, by two laboratory experiments, whether the low pH affects early stages of the semi-terrestrial crab Neohelice granulata, an estuarine and ecosystem engineer species. Firstly, embryos and the spawning larvae were exposed to acidified seawater (ambient pH: 7.9 and 8, respectively; 7.5 and 6.9); secondly, ovigerous females were collected from the field and freshly hatched larvae were cultured under these pHs. We found a slight delay in the development time of embryos exposed to pH 6.9 but no difference in those reared under intermedial pH (7.5) with respect to the control and 6.9. We also found a reduction in egg volume and eye size exposed at pH 7.5 but with a recovery to normal size later in development. Heartbeats did not vary with pH. A delay in the duration of the intermolt period was observed for both larvae zoea I (ZI) and II (ZII) exposed to pH 6.9 in the first experiment, and only in ZI under this pH in the second one. Differences in body morphometry were found in the zoeas analyzed in the first experiment but not for the second. Measurements of changes in oxygen concentration conducted in the second experiment showed a reduction in the consumption of all zoeae stages when exposed to both low pHs. Mortality of larvae remained constant across treatments. Although it was found that the early stages of this species would be slightly/moderately affected by potential future scenarios of pH decrease, we cannot rule out major impacts at the population level, which requires further experiments to be carried out.

Photoinduced behaviour of N,N-bidentate manganese(I) and rhenium(I) tricarbonyl complexes for singlet oxygen generation and CO release.

The combined action of singlet oxygen (1O2) and photoinduced carbon monoxide (CO) released by tricarbonyl metal complexes is a promising synergic treatment against multi-resistant bacterial infections. In this work, we explore the use of a polydentate ligand (bpm = 2,2-bipyrimidine) that offers the opportunity to accommodate two metal centers exhibiting both singlet oxygen generation and carbon monoxide releasing properties in a single molecule. A series of monometallic ([(bpm)M(CO)3Br]; M = Mn, Re) and homo or hetero bimetallic ([Br(CO)3M(bpm)M'(CO)3Br]; M = Mn, Re) compounds were synthesized in moderate to good yields by modulating the metal precursor or the stoichiometry, also the syn:anti isomers ratio for the bimetallic complexes was dependent on the experimental conditions used. DFT modelling shows the anti-isomer is more stable than the syn-isomer by less than 8 kJ mol-1, which is consistent with those experimentally observed in terms of majority product and the effect of experimental conditions over the anti-syn ratio. The HOMO-LUMO gap is lower for the mono and bimetallic rhenium(I) compounds compared to the values for the manganese(I) analogues, while the heterometallic complex shows intermediate values for the anti-isomer. The photophysical characterization shows typical absorption and emission bands with MLCT character. In addition, CO-release and 1O2 generation quantum yields were evaluated for the monometallic Mnbpm and Rebpm homologues and compared with values obtained for the homo- and hetero-bimetallic complexes. Interestingly the replacement of a Mn(CO)3Br moiety in MnbpmMn by a Re(CO)3Br one makes the heterometallic MnbpmRe molecule a molecular oxygen sensitizer and partially retaining its carbon monoxide releasing ability.

Engineering “Trojan Horse” disguised by cancer cell membranes for mitochondrial targeting and amplified immunotherapy

As the most promising strategy for cancer treatment, immunotherapy has attracted much attention, but its treatment effect is still blocked by the deficient immune response efficiency. In light of the significant role of mitochondria in cell metabolism, it has been considered to be a promising target to amplify immune response. In this report, a mitochondria-targeted nanodrug (UCNP@COF@FeCO/TPP@CM, UCFT@CM), camouflaged by cancer cell membrane (CM), was designed to realize cascade target and enhance immune response, further achieving the synergistic therapy of photodynamic therapy (PDT), CO gas therapy and immunotherapy. With the assistance of CM, the nanodrug exhibited significant enhancement on homologous targeting. After endocytosis, UCFT@CM would accumulate in mitochondria and realize controlled release of CO and enhanced PDT relying on the characteristics of mitochondria, further leading to serious mitochondrial oxidative stress and amplified immunotherapy. In addition, we verified that a new immune signal related to mitochondrial oxidative stress, mitochondrial transcription factor A (TFAM), is strongly associated with immunogenic cell death (ICD). Taken together, the sequenced targeting treatment makes full use of characteristics of mitochondria and provides a new approach for precisely targeting organelle to enhance the immune response.

Interfacial engineering of RuO2 for electrocatalytic decomposition of Li2CO3 in Li–CO2/O2 battery

Li2CO3, the primary byproduct of Li–CO2/O2 batteries, is challenging to decompose electrochemically and its accumulation cause the short lifespan of the battery. Herein, we report strong interfacial interaction between the intimately interfaced ultrafine RuO2 and Co3O4 nanoparticles, which leads to transfer of electrons from Ru 4d orbital to Co 3d orbital via interfacial Ru–O–Co bridges. Such intense interaction is found to boost the adsorption of CO2 and O2 on the RuO2; more importantly, it can also effectively decrease the energy barrier for the rate determining step of decomposition of Li2CO3. Therefore, both the formation and decomposition kinetics of Li2CO3 during charge and discharge are efficiently enhanced on the Co3O4-interfaced RuO2 compared to the freestanding RuO2. Using such Co3O4-interfaced RuO2 as cathode catalyst, Li–CO2/O2 (V:V = 4:1) batteries depict an overpotential as low as 1.31 V and a cycling stability of 137 cycles under a constant capacity of 1000 mAh g−1, which is significantly better than that with only Co3O4 or RuO2; the enhanced decomposition kinetics of Li2CO3 is also confirmed by monitoring the release of CO2 using in-situ mass spectrum. This work emphasizes the role of interfacial oxygen bridges in enhancing electrocatalytic decomposition of Li2CO3.

Study on the photoinitiation mechanism of carbazole-based oxime esters (OXEs) as novel photoinitiators for free radical photopolymerization under near UV/visible-light irradiation exposure and the application of 3D printing

In this work, twenty-two oxime esters bearing different functional groups and based on carbazole as the chromophore were designed and synthesized as Type I photoinitiators. Interestingly, all structures mentioned in this work have never been reported before (even for their synthesis). These oxime esters were found to have good light absorption properties in the UV–visible range, and especially at 405 nm which is a reference wavelength in photopolymerization. Noticeably, several structures showed better photoinitiation abilities than the benchmark photoinitiator i.e. diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), evidencing the interest of these structures. In order to investigate the photoinitiation mechanism of the two series of oxime esters differing by the position of the photocleavable groups, electronic absorption spectra were determined by molecular modeling and density functional theory calculations. Photopolymerization abilities of the different oxime esters and release of CO2 during the polymerization experiments were determined by Real-Time Fourier Transformed Infrared (RT-FTIR). Active free radicals were characterized by mean of Electron Spin Resonance Spin Trapping (ESR-ST) experiments. On the basis of these different complementary experiments, chemical mechanisms occurring during photopolymerization could be proposed. Experimental results showed that the decarboxylation reaction occurring subsequent to the photocleavage of oxime esters had a beneficial effect on the photoinitiation ability. Finally, 3D printed objects were successfully obtained by using oxime esters exhibiting the best photoinitiating abilities.

Synthesis of a graft‐functionalized flame retardant based on DOPO and its application on the surface of terylene/cotton fabrics

AbstractTerylene/cotton (TC) fabrics are widely used in the textile industry because of their superior softness and durability. In addition, its high combustibility leads to a great safety hazard, and the droplet phenomenon during combustion is particularly serious. 9‐oxa‐10‐phospha‐9,10‐dihydrophenanthrene 10‐oxide (DOPO) and its derivatives are frequently used as eco‐friendly flame retardants in large quantities in substrates. It would be difficult to apply to the surface of the fabric, and the addition of large amounts would lead to a decrease in the mechanical properties. Therefore, it is necessary to design a strategy for graft‐functionalized flame retardants that can be applied to surfaces. Here, this study reported a washing‐fastness flame‐retardant coating (DOPO‐p) synthesized from DOPO and p‐hydroxybenzaldehyde (p‐HBA), coatings with a low weight growth and high flame‐retardant efficiency are prepared by the strategy of dissolving with organic solvents. Water and dry‐cleaning tests showed excellent washing fastness of TC fabrics. In the limiting oxygen index (LOI) test, the finished fabric achieved a LOI value of 22.9%. In the cone calorimetry test, the peak of heat release rate of the finished fabric is decreased by 27% and CO2 release is reduced by 29% when the coating weight growth was only 3.3 wt%.

Reversible CO2 Capture and On-Demand Release by an Acidity-Matched Organic Photoswitch.

Separation of carbon dioxide (CO2) from point sources or directly from the atmosphere can contribute crucially to climate change mitigation plans in the coming decades. A fundamental practical limitation for the current strategies is the considerable energy cost required to regenerate the sorbent and release the captured CO2 for storage or utilization. A directly photochemically driven system that demonstrates efficient passive capture and on-demand CO2 release triggered by sunlight as the sole external stimulus would provide an attractive alternative. However, little is known about the thermodynamic requirements for such a process or mechanisms for modulating the stability of CO2-derived dissolved species by using photoinduced metastable states. Here, we show that an organic photoswitchable molecule of precisely tuned effective acidity can repeatedly capture and release a near-stoichiometric quantity of CO2 according to dark-light cycles. The CO2-derived species rests as a solvent-separated ion pair, and key aspects of its excited-state dynamics that regulate the photorelease efficiency are characterized by transient absorption spectroscopy. The thermodynamic and kinetic concepts established herein will serve as guiding principles for the development of viable solar-powered negative emission technologies.

Effects of microplastics on carbon release and microbial community in mangrove soil systems

Mangrove ecosystems are major carbon sink biomes and also a sink of microplastics (MPs). The final enrichment of MPs in sediments may have a significant impact on the microbial community and carbon turnover in the soil. However, the effects of MP pollution on the mangrove soil microbial communities and carbon release remain unknown. Here, we conducted a manipulative incubation experiment by adding MPs to soil at different soil depths to examine the effect of enriched MPs on soil microorganisms and its function (i.e., decomposition of soil carbon). The results showed that the addition of MPs had no significant effect on the microbial diversity and CO2 cumulative emission in the topsoil but significantly increased CO2 release from the subsoil. The promoting effect of polylactide (PLA) on the release of CO2 from the subsoil was stronger than that of polyethylene (PE) and aging PE. In the subsoil, the activity of soil extracellular enzymes related to N acquisition increased with the MP addition, indicating an increase in microbial N deficiency. The subsoil was more sensitive to MPs because of the exacerbated nitrogen limitation. MP addition reduced the microbial diversity of the subsoil and altered soil microbial interactions. The increasing abundance of some microbial taxa, especially bacteria related to the sulfur cycle, indicated more active electron transfer and organic carbon mineralization in the subsoil. Our findings suggest that MP contamination has potential effects on microbial communities, nutrient cycling, and carbon release in mangrove soils that vary depending on soil depth.

Moderate size diversity of tree roots has largest effect on the carbon loss in tropical soils

Abstract Most studies focused on the above‐ground diversity on leaf litter decomposition and soil respiration in tropical ecosystems, however, the mechanism understanding of root diversity on decomposition is still unclear. We selected the fine‐roots of 21 dominant tree species from a tropical rainforest in Xishuangbannan, China, then conducted a 360‐day and well‐replicated (21 replications) incubation decomposition experiment with a 0, 1, 3, 6, 9, 12, 15, 18 and 21 species gradient of root diversity. The fine‐root mass loss, CO2 release, and their potential drivers were analysed. The results showed that as fine‐root diversity increased, soil properties, microbial diversity and fungal biomass changed nonlinearly, leading to higher litter mass loss and soil CO2 release in the moderate diversity with 9, 12 and 15 species mixtures. Non‐additive effect analysis also indicated that synergistic effects were greater in these three mixtures than others on soil CO2 release and litter mass loss. The indirect effects of soil properties and microbial communities were larger than the direct effect of fine‐root diversity. Our findings suggest that fine‐root diversity has nonlinear relationships with litter decomposition and soil CO2 release in tropical forests, thus highlighting the importance of plant diversity due to its role in the carbon cycle under global change scenario. Read the free Plain Language Summary for this article on the Journal blog.

Disposable bamboo fiber meal boxes characterized by efficient preparation, excellent performance, and the potential for beneficial degradation

Disposable plastic meal boxes account for a significant proportion of global plastic pollution, which has caused an increasingly urgent need for substitution with biodegradable plant fiber-molded meal boxes. Compared to other chemical-mechanical pulp pre-treatment methods, steam explosion is a more efficient and clean approach for the preparation of molded meal boxes. In this study, disposable bamboo fiber meal boxes made from steam-exploded pulp (SEP) were prepared using steam explosion. The results showed that the meal boxes prepared using this method had a compact interweaving structure, good tensile performance (with a tensile modulus 1.9 times higher than that of meal boxes prepared using chemical-mechanical pulp (CMP)), excellent water resistance (with a permeability 0.58 times lower than that of CMP), high compression strength, and excellent toughness. After being discarded, SEP was found to have no adverse effects on the soil pH or electrical conductivity (EC) during the degradation process. Furthermore, it could increase the levels of major nutrients for plant growth, such as N and P, improve the C/N ratio, enhance microbial activity, and improve soil fertility. Moreover, the CO2 release rate during the entire degradation process was found to be low. Thus, the bamboo fiber meal boxes developed in this study can alleviate the environmental pressure caused by the greenhouse effect, thereby achieving a green life cycle of highly efficient preparation, stable use, and beneficial degradation.

Net effect of chemical erosion in a tropical basin on carbon cycle: Constraints from elemental and sulfur isotopic composition of the Mahanadi river water

Chemical erosion in river basins influence the climate by both consuming (via silicate erosion and carbon burial) and releasing (via H2SO4-mediated carbonate weathering and organic oxidation) atmospheric CO2. Net erosional effect of a basin on carbon cycle, therefore, requires precise rate assessment of all these pathways; combined data for the four processes for a given basin are sparse. In this contribution, we have quantified these process intensities for a large tropical basin (Mahanadi river) from the eastern part of India using new time-series (weekly) data for dissolved major ions and sulfur isotopes, and compiled data for rhenium concentrations and particulate carbon isotopes for the basin. The discharge-weighted silica concentrations (∼215 μM) of these samples is higher than that reported as global average for rivers (∼145 μM), indicating intense silicate erosion in the basin. The δ34S of the riverine sulfates vary between 8.8 ‰ and 17 ‰, with a discharge-weighted average of 12 ± 4 ‰ (global riverine value ∼4.4 ± 4.5‰). Temporal changes in concentrations for most of the elements (and δ34S) show relatively higher (enriched) values during lean-flow stages. Mass balance calculations involving Ca, Mg and Si values confirm that these seasonal changes are mainly due to increase (by 18 ± 9%) of groundwater supply to the stream during non-monsoon seasons. The silicate-derived cations (Catsilicate) for the Mahanadi show minimal changes during monsoon (36 ± 5%) and non-monsoon (33 ± 8%) seasons. These data correspond to a CO2 consumption rate of 2.4 ± 1.6 tC/km2/yr, which is about two times higher than that reported for global rivers. Comparison of δ34S values of riverine sulfate with its possible sources computes the relative supply of sulfates from atmospheric deposition (38%), gypsum (46%), and sulfides (16% (a lower limit)) to the river. The minimal contribution via sulfide oxidation confirms low CO2 release (0.1 ± 0.1 tC/km2/yr) in this basin through sulfuric-acid mediated carbonate weathering. Average rhenium for this river is 5 ± 3 pmol/kg. The source apportionment using S/Re and Na/Re ratios indicates that 85 ± 10% of the Re is derived through organic oxidation. The rhenium data are used to estimate the CO2 release rate (0.50 ± 0.57 tC/km2/yr) by oxidation of petrogenic carbon, which is higher than the estimated organic burial rate (0.27 ± 0.12) for the basin. The estimated four erosion rates confirm a net negative (∼ − 2.1 ± 1.7 tC/km2/yr) effect of chemical erosion in the Mahanadi basin on the CO2 budget. Low sulfide-oxidation in this supply-limited regime is possibly linked to limited exposure of fresher minerals, whereas high silicate erosion in the basin is consistent with its silicate-dominated lithology and tropical climate.

Construction of macromolecular structure in KunNing coal and analysis of Macro-Micro oxidation characteristics

To explore the macro–micro coal oxidation characteristics for the purpose of preventing coal spontaneous combustion and achieving efficient coal conversion and utilization, the enclosed coal oxidation characteristics of KunNing coal sample (KN) under 25–70 °C were investigated. KN coal molecular models were constructed based on analysis and testing results of X-ray Photoelectron Spectroscopy (XPS), Carbon-13 Nuclear Magnetic Resonance Spectroscopy (13C NMR), Fourier Transform Infrared Spectroscopy (FTIR) and other techniques. The pyrolysis processes of coal-oxygen reaction systems with different oxygen contents were simulated using ReaxFF force field. The results show that the oxygen consumption rate, CO release rate, CO2 release rate and oxidation heat release intensity of coal increase exponentially with rising temperature. The ratio of aromatic bridge carbon to peripheral carbon in KN coal molecular structure is 0.08, and the molecular formula is C149H76O15N2S2. In the later stage of the experimental and molecular dynamics simulation processes, the CO content decreased while the growth rate of CO2 increased. Different indicator gases exhibit varied responses to oxygen content. The C-atom labeling and traceback results for the four indicator gas molecules demonstrate that CO2 mainly comes from aldehyde, hydroxyl, carboxyl and methoxy groups in coal molecules, CO is primarily generated from esters, phenols, carbonyls, C2H2 is predominantly derived from ring-opening and cracking of cycloalkanes, and the source of C2H4 is related to cycloalkanes and alcohols.

Enhanced effects of symbiosis between Tribonema sp. and aerobic denitrifying phosphorus accumulating bacteria on wastewater treatment and greenhouse gas reduction

The traditional biological wastewater treatment process faces issues of inefficiency and high greenhouse gas emissions. This study firstly established a symbiotic system between Tribonema sp. and Pseudomonas sp. (an aerobic denitrifying phosphorus accumulation bacteria). Results showed that co-culture systems significantly increased the removal rates of nutrients from wastewater and the biomass and lipid content of both microorganisms. The optimal inoculation ratio was 25:1, resulting in the removal rates of PO43--P, NH4+-N, NO3--N, TN and TOC increased by up to 31.47%, 133.12%, 39.84%, 206.54%, 31.92%, and an increase of 6.72% and 80.11% in the biomass of Tribonema sp. and Pseudomonas sp., respectively, compared to single cultures. CO2 release from respiration exceeded CO2 fixation by microalgae. The CH4 concentration in co-culture systems was lower than that in single cultures, with low levels of N2O detected. This symbiotic system effectively transforms wastewater nutrients into biomass resources while minimizing greenhouse gas emission.

Seaweed farming environments do not always function as CO2 sink under synergistic influence of macroalgae and microorganisms

Seaweed farming contributes substantial amounts of organic carbon to the ocean, part of which can be locked for a long term in the ocean and perform the function of ocean carbon sequestration, and the other part can be converted into inorganic carbon through microbial mineralization and aerobic respiration, affecting the pCO2, pHT and dissolved oxygen of seawater. It is generally believed that seaweed farming will cause the seawater to become a sink of CO2 due to carbon fixation by macroalgal photosynthesis. However, little attention has been paid to the fact that seaweed farming environment may sometimes become a source rather than a sink of CO2. Here, through in-situ mesocosm cultivation experiments and eight field investigations covering different kelp growth stages in an intensive farming area in China, we found that compared with the surrounding seawater without kelps, the seawater at the fast-growth stage of kelp was a sink of CO2 (pCO2 decreased by 17−73 μatm), but became a source of CO2 at the aging stage of kelp (pCO2 increased by 20−37 μatm). Concurrently, seawater pHT experienced a transition from increase (by 0.02−0.08) to decline (by 0.03−0.04). In-situ mesocosm cultivation experiments showed that the positive environmental effects (i.e., pCO2 decrease and pHT increase) induced by kelps at the early growth stage could be offset within only 3 days at the late-growth and aging stages. The release of dissolved organic carbon by kelps at the late growth stage increased significantly, supporting the enhancement in microbial abundance and respiration, which was manifested by the remarkable decrease in seawater dissolved oxygen, ultimately leading to CO2 release exceeding photosynthetic CO2 absorption. This study suggests that mature farmed kelps should be harvested in time to best utilize their carbon sink function and environmental benefits, which has guiding significance for the rational management of seaweed farming.

Development of a two-dimensional model to assess carbon dynamics and anthropogenic effects on CO2 emissions in the Tan river, southern China

Tidal rivers are key biochemical reaction channels along the land-ocean aquatic continuum, receiving carbon from wastewater and agricultural drains, which can considerably affect CO2 emissions. We developed a two-dimensional hydrodynamic and ecological model coupled with an inorganic carbon module along the Tan River in southern China. The simulations of and observations regarding discharge, temperature, total organic carbon (TOC), total inorganic carbon (TIC), and other common water quality variables were generally in good agreement. Based on the validated model, we employed statistical and scenario analyses to evaluate the carbon distribution, TOC and TIC budgets, and the imbalances induced by climatic and anthropogenic changes, providing insights into their potential greenhouse effect. The Tan River was consistently supersaturated with CO2 with an annual mean air-water CO2 emission flux (FCO2) of 226.1 ± 84.9 mmol m−2 d−1, and significant temporal and spatial variations of FCO2, TOC, and TIC were observed. Urban small streams tended to emit additional CO2 during wet seasons, and rural tributaries usually had an increase in TOC concentrations during the dry season. FCO2 was significantly positively correlated with air temperature and negatively correlated with total nitrogen, total phosphorus, and TOC. The annual riverine input of carbon to the urban river network was 17.37 Gg C yr−1, with 59.82% of TOC, and carbon output was 15.31 Gg C yr−1, with 66.87% of TOC. The retention rates for TOC and total carbon were 50.7% and 11.8% in the urban branch, respectively. Furthermore, warming and wastewater treatment could prevent urban river networks and downstream rivers from becoming carbon sources. Therefore, our findings suggest that riverine management strategies change the global CO2 release from tidal rivers and estuarine systems under climate change.

Pyrolysis interaction of cellulose, hemicellulose and lignin studied by TG-DSC-MS

The pyrolysis kinetics, heat endothermic and exothermic characteristics and gases formation of cellulose, hemicellulose, lignin and their mixtures were investigated by TG-DSC-MS to understand the interaction of biomass three components and its influence on the pyrolysis gas products. It was found that there were complex interactions among three components, and the activation energy of mixtures pyrolysis was mainly divided into two stages. During the pyrolysis process, cellulose could promote the decomposition of lignin and hemicellulose, while hemicelluloses might restrain the decomposition of cellulose and lignin. Furthermore, lignin promoted the decomposition of hemicelluloses but inhibited the decomposition of cellulose. The interactions also had a great influence on the gas products. The gas products generated during pyrolysis of three components were mainly H2, CO, H2O and CO2. Hemicellulose and lignin promote H2 release, while cellulose and lignin inhibit the release of H2O and CO2, and all three components restrain the release of CO. The effect of hemicellulose on H2O and CO2 would depend on pyrolysis temperature of 325 °C.

Livestock grazing and biodiversity: Effects on CO2 exchange in semi-arid Karoo ecosystems, South Africa

Livestock use in semi-arid South African ecosystems has not been extensively studied in relation to the Net Ecosystem Exchange (NEE) of carbon dioxide (CO2). We present four years of measurements from twinned eddy-covariance towers in Nama-Karoo, South Africa, to investigate the carbon fluxes and the impact of grazing intensity on NEE. The design contrasted NEE at a long-term site grazed at recommended levels (LG) with a long-term heavily grazed (EG) site that had been rested for 10 years, and was monitored for two years after which intensive grazing was reintroduced for this experiment. This allowed for the quantification of long-term NEE trends on “recovering” vegetations (years I, II) and short-term responses to an intensified land use (years III, IV). The results showed that the net release of CO2 was slightly higher at LG than on “recovering” vegetation at the EG site, where near-neutral exchange was observed during years I and II. However, after grazing was reintroduced to the EG site, differences between sites was reduced but not eliminated. These findings suggest that there is a somewhat higher carbon sequestration potential at the resting EG site than at the LG site, apparently associated with the dominance of unpalatable drought-tolerant grass species and local elimination of many palatable shrubs. Reduction of this sink potential by reintroduction of high-intensity grazing indicates the sensitivity of C-sequestration in this “recovering” system to heavy grazing, but underlines continued resilience of NEE under far heavier grazing than in the LG system. These data suggest notable trade-offs in these ecosystems between carbon storage, biodiversity, and livestock production with rainfall variability being a critical inter-annual driver. Plain language summaryThis study suggests that long-term resting of previously over-utilized southern African semi-arid vegetation supports enhanced carbon sequestration potential, even if over-utilization has transformed vegetation composition (i.e. has caused degradation through reduced plant species richness). However, this enhanced carbon sequestration potential can be quickly negated by the reintroduction of grazing, even after 10 years of resting. Achievement of carbon sequestration is dependent on average to above-average precipitation and its distribution throughout the year, with sink activity evident mainly after seasonal rains during the warm season.

Assessment of the Fermentative Performance of Traditional Fresh Moroccan Sourdoughs and Their Freeze-Dried Forms Using Online Monitoring Device: Panigraph

The fermentative activity of sourdoughs and their stabilities are some of the main concerns of professionals in food science. The aim of this study was to evaluate the fermenting capacity of three traditional fresh sourdoughs and their freeze-dried forms with different compositions prepared by housewives in three different regions of Morocco. A device equipped with several sensors was developed to monitor several parameters simultaneously and in real time (the pH, dough rise, loss of mass, CO2 and ethanol release). The results showed that the duration of dough fermentation was long, ranging from 594 to 1210 min, with the specific volume ranging from 0.9 to 3.35 cm3/g−1. A strong and positive correlation between dough rise and CO2 release was observed, while ethanol release did not contribute directly to dough rise. The fresh sourdough FS1 showed better fermentative performance than the others, while the freeze-dried sourdough FDS3 was also of interest for bread making. The system used to generate the graphical fingerprints enabled us to read the main fermentation parameters directly in the same graph, as well as to compare several sourdoughs at once and choose the one best suited to our needs.

Benthic Respiration and Heavy Metal Benthic Fluxes in Artificial Shihwa Lake: Approaching In Situ Measurement

This study assessed the impact of intensive human activities on organic matter (OM) and heavy metal cycles in Shihwa Lake, South Korea. Sediment oxygen demand (SOD), benthic nutrient flux (BNF), and benthic heavy metal flux were estimated using in situ benthic chambers. The combined analysis of sediment trap and SOD showed that the vertical supply of OM was a major controlling factor for benthic respiration. The BNF accounted for 35–144% and 32–184% of the N and P required, respectively, for primary production (PP) in the water column. The higher SOD may have also accelerated the release of Mn, Fe, Co, and Ni from the sediment. Benthic fluxes of Cr, As, Cd, Pb, Cu, and Zn were highest near the industrial complex, with ranges of 1.3 ± 0.9, 6.4 ± 4.9, 0.2 ± 0.1, 0.5 ± 0.4, 7.7 ± 1.4, and 452 ± 133 μmol m−2 d−1, respectively. Mn, Fe, Co, As, Pb, Ni, and Cu contributed more than 10% of the sediment to the current standing stock at Shihwa Lake.

Flame‐retardant epoxy resin with good smoke‐suppression endowed by chitosan–cobalt/phosphorus complex

AbstractChitosan‐based flame‐retardant CS–Co–DOPA (CCD) was synthesized by the neutralization reaction of 10‐hydroxy‐9,10‐dihydro‐9‐oxo‐10‐phosphaphenanthrene‐10‐oxide (DOPA) with chitosan‐cobalt complex and fully characterized by scanning electron microscopy (SEM), energy‐dispersive spectrometer, x‐ray diffraction, X‐ray photoelectron spectroscopy (XPS), optical emission spectrometer, and Fourier transform infrared (FTIR) characterizations. The epoxy resin (EP) modified with CCD exhibited good flame retardancy. With the addition of 5 wt% CCD, the EP/CCD achieved UL‐94 V‐1 rating and possessed limiting oxygen index (LOI) value of 30%. Cone calorimetry (CC) test demonstrated that EP/CCD resulted in a remarkable reduction of peak smoke production rate (pSPR) and total smoke production (TSP) by 63% and 40%, respectively, showing an outstanding smoke suppression. The char residue obtained from the CC test was further characterized using SEM, FTIR, Raman, and XPS techniques. The results revealed that CCD facilitated the formation of a dense and compact char layer on EP during combustion, thereby impeding gas and heat transfer. In addition, TG‐IR was employed to investigate the gas‐phase flame‐retardant effect of EP/CCD composites, which revealed that CCD promotes the release of water, CO2, and other incombustible gases, altering the decomposition path of EP.