Production Of Organic Matter Research Articles

Hydrological controls of a riparian wetland based on stable isotope data and model simulations.

Isotopic evidence of groundwater and stream water is frequently used to investigate water exchanges with groundwater. Monthly sampling of rain, stream water, and groundwater was conducted at Tims Branch watershed in South Carolina for the oxygen and hydrogen stable isotope (δ2H and δ18O) measurement, as well as pH and oxidation-reduction potential (ORP). Together with a mass balance perspective, it was determined that it takes a few weeks to one month for groundwater in the hyporheic zone to fully exchange with stream water. From hydrodynamic modelling, we show that substantial (up to 70 %) groundwater exchange occurs at gaining and losing sites. Groundwater exfiltration, i.e. inflow into stream water, contributes up to 4 % to stream water, with the remainder from upstream exfiltration. A 2-4 % per day renewal rate of adjacent groundwater would indirectly indicate a groundwater residence time in the order of half a month to a full month (assuming either a well-mixed case or large dispersion rate in pulse flow case), in agreement with a greatly reduced variability of δ2H and δ18O of groundwater compared to stream water and rain. This reduced variability of stable isotope signal from groundwater confirms our hypothesis that riparian groundwater mixing at Tims Branch is more of a mixed type rather than a pulse flow type. A monthly time scale is sufficient for groundwater to become anoxic at exit points into stream water resulting in the episodic production of natural organic matter- and iron-rich flocs upon oxidation.

Fermentation and Nutritive Value of Pineapple Stubble Silage Supplemented with Leucaena Hay

The increase in pineapple production has generated a large amount of waste, which, when incorporated into the soil, can lead to contamination and environmental degradation. In this context, this study highlights the innovative combination of pineapple waste and Leucaena hay, offering benefits for animal nutrition while reducing input costs. The objective of this study was to determine the nutritional value of silage from ‘Pérola’ pineapple waste (PS) with different levels of Leucaena hay. A completely randomized design was adopted with six treatments (pre-wilted PS and PS with 0%, 10%, 20%, 30%, and 40% inclusion of Leucaena hay (LH)). The dry matter content of the silage, crude protein, lignin, and pH increased linearly (p < 0.05) as a function of the inclusion of Leucaena hay, while buffering capacity, soluble carbohydrate content, and effluent losses showed an inverse relationship. As LH levels increased, ruminal DM disappearance decreased. Wilting the pineapple plant did not alter the in vitro gas production, in vitro digestibility of organic matter, partition factor (PF), and methane production when compared to the silages added with Leucaena hay. It is recommended to add 20% Leucaena hay in PS silage.

Dissolved organic matter (DOM) rather than warming and eutrophication directly affects partial pressure of CO2 (pCO2) in mesocosm systems

Environmental warming and eutrophication pose significant challenges to shallow lake systems, where dissolved organic matter (DOM) serves as a diverse and intricate mixture of organic macromolecules, playing a pivotal role in aquatic ecosystems. Despite its complexity, comprehending the interplay between environmental changes and DOM composition alterations and their subsequent impacts on aqueous CO2 partial pressure (pCO2) is essential for a better understanding of carbon cycling. Yet, our current understanding in this realm remains limited. To address this gap, mesocosm systems were established to investigate how elevated water temperature and eutrophication, alongside changes in DOM composition, influence pCO2 dynamics. Results indicate that while temperature and nutrient levels do not directly influence pCO2 fluctuations, they indirectly affect aqueous pCO2 through their modulation of DOM composition. Elevated temperature and nutrient concentrations notably enhance both the production and degradation of indigenous protein-like organic matter and increase the accumulation of humic-like organic compounds, with phosphorus released from sediment playing a particularly significant role. Furthermore, the degradation rate of protein-like organic matter significantly exceeds its accumulation rate. On the other hand, the impact of water eutrophication on DOM composition surpasses that of temporal temperature variations, with a 2∼4 °C temperature rise showing minimal effects on DOM composition. Notably, the degradation of protein-like organic matter markedly increases aqueous pCO2, while the rise in humic-like organic matter in water exerts minimal influence on pCO2 concentrations. A comprehensive understanding of carbon cycling processes under environmental changes will facilitate effective management of lake ecosystems and the advancement of carbon mitigation technologies.

Residues of Symbiont Cover Crops Improving Corn Growth and Soil-Dependent Health Parameters

Cover crops have emerged as a crucial tool in promoting sustainable agricultural practices, particularly in improving soil quality and soil–plant health. This study investigates the impact of single cover crop plants each with varying fungal and/or bacterial symbiosis capacities in a pot experiment. The growth of non-symbiont Ethiopian mustard (Brassica carinata), the associative bacterium symbiont black oat (Avena strigosa) and the double (fungus–bacterium) endosymbiont broad bean (Vicia faba) was studied on three distinct soil types, namely a less-fertile sandy soil (Arenosol), an average value of loam soil (Luvisol) and a more productive chernozem soil (Chernozem). Beside the biomass production, nitrogen content and frequency of AM fungi symbiosis (MYCO%) of cover crops, the main soil health characteristics of electrical conductivity (EC), labile carbon (POXC) and fluorescein diacetate enzyme activity (FDA) were assessed and evaluated by detailed statistical analysis. Among the used soil types, the greatest biomass production was found on Chernozem soil with the relatively highest soil organic matter (2.81%) content and productivity. Double symbiotic activity, assessed by soil nitrogen content and mycorrhiza frequency (MYCO%), were significantly improved on the lowest-quality Arenosols (SOM 1.16%). In that slightly humous sandy soil, MYCO% was enhanced by 45%, indicating that symbiosis was crucial for plant growth in the less-fertile soil investigated. After the initial cover crop phase, the accumulated biomass was incorporated into the Luvisol (SOM 1.64%) soil, followed by the cultivation of corn (Zea mays, DK 3972) as the main crop. The results indicate that incorporating cover crop residues enhanced labile carbon (POXC) by 20% and significantly increased the FDA microbial activity in the soil, which positively correlated with the nutrient availability and growth of the maize crop. This study emphasizes the importance of selecting suitable cover crops based on their symbiotic characteristics to improve soil quality and enhance soil–plant health in sustainable agricultural systems.

Carbon stocks in mangrove ecosystems of Sri Lanka: Average contributions and determinants of sequestration potential

Mangroves are crucial in carbon sequestration despite covering only a small percentage of the Earth's surface. Latitudinal gradient primarily determines the distribution of climatic zones of distinct sunlight, temperature, and precipitation patterns, which influence the community structure of the mangrove ecosystem. The tropical climate of Sri Lanka contributes to the island's lush mangrove forests. The present study estimated that the average island's carbon sequestration capacity of Sri Lankan mangrove ecosystems is 524.25 t/ha representing a substantial volume of carbon storage that contributes to offset greenhouse effect due to increasing atmospheric CO2. Our results substantiated that rainfall positively influences total carbon sequestration capacity of mangrove ecosystems.It was also revealed that a positive relationship exists between vegetation structural complexity and sediment organic carbon, highlighting the influence of vegetation structure, that is primarily dependent on climatic conditions, on production of organic matter and sediment carbon sequestration. Globally, the carbon sink function of mangrove ecosystems is reported to be highest in the tropical areas and it declines towards sub-tropical higher latitudes while those in the southern hemisphere perform better carbon sinks than those in the northern hemisphere.The vertical distribution of total organic matter content in mangrove sediments was revealed to be in a descending order, manifesting the weak tidal removal of surface organic matter under the microtidal conditions in Sri Lankan marine waters, thus qualifying mangrove ecosystems in microtidal coasts as effective carbon sinks.

Upwelling current and its relationship to the enrichment of organic matter in the Lower Silurian Longmaxi Formation, northern Chongqing–western Hubei area, southern China

Upwelling currents play a crucial role in the enrichment of organic matter, yet the mechanisms driving this process remain incompletely understood due to methodological and data resolution limitations. In this paper, we employ a combination of biostratigraphic classification, qualitative methods, and quantitative methods to systematically analyze the sedimentological and geochemical characteristics of the Lower Silurian Longmaxi Formation in the northern Chongqing–western Hubei area, southern China. The relationship between the upwelling currents and organic matter enrichment in the shale of the Longmaxi Formation is investigated. Results indicate that the upwelling currents in the study area were primarily influenced by the foreland flexure process. From the Rhuddanian (flexure–sedimentation stage) to the Aeronian (flexure–migration stage), the more intense tectonic activity led to gradual opening of the barrier between the South Qinling Ocean and the Yangtze Platform, resulting in an increase in the influx of the oceanic current. The upwelling currents significantly contributed to the organic matter production, albeit without substantially affecting the preservation conditions. Throughout the succession of the Longmaxi Formation, the organic matter content decreased gradually from the passive continental margin to the foreland flexural stagnant basin, which was mainly due to deterioration of the preservation conditions as a result of sea level fall and increased terrigenous input. Despite the increase in the upwelling currents, they did not decisively control the organic matter enrichment. Spatially, during the Rhuddanian to Aeronian period, the organic matter content decreased similarly from the passive continental margin to the foreland flexural stagnant basin, influenced by reduced organic matter production caused by weakening of the upwelling currents and the worsening preservation conditions caused by sea-level fall. The terrigenous input had a relatively minor impact. The results of this study provide new insights into the role of upwelling currents in the organic matter enrichment within the Longmaxi Formation, overcoming previous methodological and resolution barriers.

Effects of biochar and wood vinegar co-application on composting ammonia and nitrous oxide losses and fertility

Composting faces challenges with nitrogen (N) losses through ammonia (NH3) and nitrous oxide (N2O) emissions. In this study, wood vinegar (WV) and biochar (BC) were applied individually or combined into wheat straw and chicken manure composting. Results showed that BC and WV reduced NH3 volatilizations by 22–23 % individually, but their combined application achieved a 59 % reduction. However, this combination increased N2O emissions by 174 %. The BC + WV treatment improved compost quality, evidenced by increased total N content by 22 % and enhanced the biological index, promoting additional dissolved organic matter production. Overall, BC and WV applications improved compost quality, reduced gaseous N losses, and supported the re-utilization of agricultural residues. The combined use of BC and WV significantly enhances compost quality and reduces NH3 emissions, offering a promising solution for sustainable agricultural residue management.

Upwelling-driven high organic production in the late Ediacaran

The Ediacaran ocean (635-541 million years ago) is typically viewed as a stagnant, redox-stratified ocean with low phosphorus availability. However, this contradicts the high total organic carbon (up to 15 wt%) recorded in the upper Ediacaran Doushantuo Formation in South China. Here, we present a quantitative reconstruction of primary productivity and sediment total organic carbon using basin-scale simulations based on various redox-nutrient scenarios. Our results indicate that oceanic upwelling was the primary driver of enhanced primary productivity, with estimates over 2.5 times the modern ocean’s average, providing quantitative evidence for oceanic circulation in the Ediacaran Nanhua Basin. Our results also indicate the development of spatially linked but opposing redox trends, i.e., a ‘redox anticouple’, whereby the expansion of the oxic surface layer occurred concurrently with intensification of deep-water anoxia due to enhanced PP in surface and its consumption of oxidants in underlying waters. This model may explain the conflicting redox records across the Nanhua Basin. Our findings explain the unusually high rates of organic matter production and preservation in the low-pO2 Ediacaran ocean and provide a mechanism for its progressive oxygenation.

An algal regulation-based molasses vinasse anaerobic digestion strategy for enhancing organic matter removal and methane production

Microalgae are suitable type of anaerobic co-digestion (AcoD) substrate that can effectively alleviate microbial inhibition caused by substrate characteristics (molasses vinasse, MV). Therefore, our investigated the synergistic effects, organic matter removal, and potential microbiological impacts in the AcoD of MV and Desmodesmus opoliensis strain GXU-A4. We conducted batch AcoD using simple dehydrated GXU-A4 (Fresh D. opoliensis, FDO) and lipid-extracted GXU-A4 (Pretreated D. opoliensis, PDO). The highest methane potential of PDO biomass was 124.9 ± 0.8 mL g−1 VS, while AcoD with MV increased methane production by 11 % and promoted acetic acid production. FDO biomass reduced nitrogen-containing organic matter and humic-like production. Microbial community and functional prediction analyses revealed that AcoD altered the distribution of hydrolytic acidogenic bacteria, such as Bacteroidetes and Cloacimonadota (W5). Our study provide a new insight into the control strategy of AcoD for methane production, removal of organic matter, and microbial mechanisms in algae biomass.

Modelling Mediterranean ocean biogeochemistry of the Last Glacial Maximum

Abstract. We present results of simulations performed with a physical–biogeochemical ocean model of the Mediterranean Sea for the Last Glacial Maximum (LGM) and analyse the differences in physical and biochemical states between the historical period and the LGM. Long-term simulations with an Earth system model based on ice sheet reconstructions provide the necessary atmospheric forcing data, oceanic boundary conditions at the entrance to the Mediterranean Sea, and river discharge to the entire basin. Our regional model accounts for changes in bathymetry due to ice sheet volume changes, reduction in atmospheric CO2 concentration, and an adjusted aeolian dust and iron deposition. The physical ocean state of the Mediterranean during the LGM shows a reduced baroclinic water exchange at the Strait of Gibraltar, a more sluggish zonal overturning circulation, and the relocation of intermediate and deep-water-formation areas – all in line with estimates from palaeo-sediment records or previous modelling efforts. Most striking features of the biogeochemical realm are a reduction in the net primary production, an accumulation of nutrients below the euphotic zone, and an increase in the organic matter deposition at the seafloor. This seeming contradiction of increased organic matter deposition and decreased net primary production challenges our view of possible changes in surface biological processes during the LGM. We attribute the origin of a reduced net primary production to the interplay of increased stability of the upper water column, changed zonal water transport at intermediate depths, and lower water temperatures, which slow down all biological processes during the LGM. Cold water temperatures also affect the remineralisation rates of organic material, which explains the simulated increase in the organic matter deposition, which is in good agreement with sediment proxy records. In addition, we discuss changes in an artificial tracer which captures the surface ocean temperature signal during organic matter production. A shifted seasonality of the biological production in the LGM leads to a difference in the recording of the climate signal by this artificial tracer of up to 1 K. This could be of relevance for the interpretation of proxy records like, e.g., alkenones. Our study not only provides the first consistent insights into the biogeochemistry of the glacial Mediterranean Sea but will also serve as the starting point for transient simulations of the last deglaciation.

Inventory of Pollution Sources for The Lakes of Universiti Tun Hussein Onn Malaysia

Eutrophication affects freshwater systems worldwide. Eutrophication can occur naturally, but man-made causes are also common. Human activities that release phosphorus and nitrogen lead to anthropogenic eutrophication, which increases organic matter production. Lake eutrophication affects surface waters all over the world. Water pollution can be assessed regarding point sources (PS) and non-point sources (NPS). PS is the intentional or unintentional release of pollutants from industrial and wastewater facilities into waterways. Agriculture, urban development, and natural processes in the lake's catchment area can cause NPS pollution. NPS pollution has many causes, including precipitation, airborne deposition, infiltration, drainage, and fluctuations in water flow in the catchment. The pollution inventory was conducted in UTHM lakes such as Tasik Kemajuan, Tasik Teknologi (FKAAB), Tasik Teknologi (FPTV), and Tasik Pembangunan. The PS and NPS in the study area were assessed through an on-site investigation. The UTHM water discharge plan is being analyzed to determine the inflow sources into the lake. The PS pollutant inventory revealed that the cafeteria wastewater, business buildings, and faculty drainage systems pollute all lakes. Tasik Teknologi (FPTV) identified runoff from palm oil plantations as a source of pollutants that can increase the nutrient content of the lake. Leaves, grass clippings, and other garden waste were in the water in all the lakes analysed. The Tasik Kemajuan, the Tasik Teknologi (FKAAB), and the Tasik Teknologi (FPTV) received water discharges from other lakes transporting pollutants. The assessment of pollutant sources revealed that most NPS originate from surface runoff. Road runoff contains several pollutants. Stormwater runoff or surface runoff can carry these pollutants from roads into waterways. Stormwater washes fertilizers into storm drains and lakes. To summarise, all pollutant sources that contributed to the eutrophication of the Tasik Kemajuan, Tasik Teknologi (FKAAB), Tasik Teknologi (FPTV), and Tasik Pembangunan were identified through a pollutant source inventory.

Hypoxia Triggered by Expanding River Plume on the East China Sea Inner Shelf During Flood Years

AbstractThe frequency of riverine floods is predicted to increase in East Asia. However, the response of coastal hypoxia (<63 μmol L−1) to floods has not been well understood. In the summer of 2020, characterized by one of the most significant Changjiang water fluxes in three decades, we conducted a cruise during the flood period on the East China Sea inner shelf. Our observations revealed severe bottom hypoxia with a maximum spatial coverage of ∼11,600 km2 and a minimum dissolved oxygen concentration (DO) of 21 μmol L−1. In the surface layer, the relationships between salinity and nitrate, dissolved inorganic carbon (DIC) indicated significant organic matter production, validated by a high‐Chlorophyll‐a (Chl a) patch (>5 μg L−1). Furthermore, the significant relationship between apparent oxygen utilization and DIC of deep waters reveals that the organic matter decomposition primarily drove the hypoxia during the flood period. Episodic wind events also influenced bottom DO and DIC, by transporting surface waters to the deep. Multiple‐years data set shows that the average Changjiang nitrate flux during flood years is about 1.4 times that during non‐flood years. The flood waters mix with estuarine waters, forming the high‐nutrient plume waters, which expanded farther offshore during the flood period. While high turbidity remained confined to the inner estuary. Consequently, the high‐Chl a area significantly expanded, which significantly exacerbated the hypoxia.

NUTRITIONAL VALUE AND IN VITRO DRY MATTER DEGRADABILITY IN MEXICAN SUNFLOWER: Tithonia diversifolia Helms (Gray)

<p><strong>Background</strong>: <em>Tithonia diversifolia</em> Helms (Gray), is a robust shrubby forage plant with high integral biomass yield (stem and leaves); susceptible to heliophany and conditioning of bromatological characteristics, nutritional value, and modification of the rumen environment is due to genetic variability between genotypes. <strong>Objective:</strong> To evaluate the macromolar quality of the biomass of introductions <em>T. diversifolia</em> Helms (Gray) established in two locations, and the nutritional value, gas production and <em>in vitro</em> rumen environment promoted by the whole plant biomass established in Ecuador. <strong>Methodology:</strong> The chemical composition of the full plant (PITD) was considered based on Dry Matter (DM), Organic Matter (OM), Mineral composition (MC), Crude Protein (CP), neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF). I<em>n vitro</em> gas production was evaluated according to Ankom Technology, considering Tiffon 85 there (<em>Cynodon dactylon</em>) at control, quantified or ammoniacal nitrogen (N-NH<sub>3</sub>), short-chain fatty acids (SCFA) and pH. The experiment was developed in a completely randomized design in factorial arrangement with three repetitions for the variable chemical composition, and the <em>in vitro</em> digestibility of the date processed through a random complete block design with six repetitions, in the ruminal ambient and production SCFA was analyzed through a completely randomized block design with three repetitions. <strong>Results:</strong> There were variable responses in the DM content for the effect of interaction P <0.01, and higher mineral content in El Carmen, Ecuador for introduction 13.5, with respect to the rest of the cultivars in both locations. NDF was significantly expressed (p<0.001) in variety 1.2 that grew in Candelaria, Ecuador. For the rest of the variables, no differences were recorded (P>0.05). The gas production of the introductions, except for 1.2, was similar to that produced by the control (Tifton 85), however, in the degradability of the OM, net gas production (Net GP) of DM and OM, stood out. introduction 1.2 compared to the control (P<0.01) and the rest of the introductions. The net GP of NDF exceeded 1.2 (p<0.02) than the control, also quantitatively to produce Acetic and Propionic Fatty Acid. <strong>Implications:</strong> The introductions of <em>T. diversifolia</em> Helms Gray based on the results obtained preserve macromolar characteristics, gas production and SCVFA production (short chain volatile fatty acids) in contrasting ecosystems such as Valle del Cauca, Colombia and Manabi in Ecuador. <strong>Conclusions:</strong> The introductions of <em>T. diversifolia</em> Helms Gray, maintain a good protein composition, produce low methane contents, have high performance in the fermentation of organic matter and the cell wall, which suggests its future use as a complement to the ration in conditions in conditions Edaphoclimatic of the province of Manabi.</p>

Unveiling a new oceanic anoxic event at the Norian/Rhaetian boundary (Late Triassic)

The latest Triassic was characterised by protracted biotic extinctions concluding in the End-Triassic Extinction (~ 200 Ma) and a global carbon cycle perturbation. The onset of declining diversity is closely related to reducing conditions that spread globally from upper Sevatian (uppermost Norian) to across the Norian-Rhaetian boundary, likely triggered by unusually high volcanic activity. We correlate significant organic carbon cycle perturbations to an increase of CO2 in the ocean–atmosphere system, likely outgassed by the Angayucham igneous province, the onset of which is indicated by the initiation of a rapid decline in 87Sr/86Sr and 188Os/187Os seawater values. A possible causal mechanism involves elevated CO2 levels causing global warming and accelerating chemical weathering, which increased nutrient discharge to the oceans and greatly increased biological productivity. Higher export production and oxidation of organic matter led to a global O2 decrease in marine water across the Norian/Rhaetian boundary (NRB). Biotic consequences of dysoxia/anoxia include worldwide extinctions in some fossil groups, such as bivalves, ammonoids, conodonts, radiolarians.

Changes in phytoplankton size–structure alter trophic transfer in a temperate, coastal planktonic food web

AbstractMicrozooplankton grazing is an essential parameter to predict the fate of organic matter production in planktonic food webs. To identify predictors of grazing, we leveraged a 6‐yr time series of coastal plankton growth and grazing rates across contrasting environmental conditions. Phytoplankton size–structure and trophic transfer were seasonally consistent with small phytoplankton cell dominance and low trophic transfer in summer, and large cell dominance and higher trophic transfer in winter. Departures from this pattern during two disruptive events revealed a critical link between phytoplankton size–structure and trophic transfer. An unusual summer bloom of large phytoplankton cells yielded high trophic transfer, and an atypical winter dominance of small phytoplankton resulted in seasonally atypical low trophic transfer. Environmental conditions during these events were neither seasonally atypical nor unique. Thus, phytoplankton size–structure rather than environmental conditions held a key‐role driving trophic transfer. Phytoplankton size–structure is easily measurable and could impart predictive power of food‐web structure and the fate of primary production in coastal ecosystems.

Characterization of natural organic matter in Wyoming-type bentonites irradiated at varied moisture levels

Wyoming-type bentonite clay (MX-80; Wyoming, USA) will be used in a deep geological repository (DGR) for the long-term storage of used nuclear fuel in Canada. The natural organic matter (NOM) found in bentonite may serve as a microbial nutrient source and potentially compromise the performance of the used fuel containers. Previous investigations indicate that NOM is present in low concentrations in MX-80 and has undergone extensive diagenetic alteration, though limited knowledge is available regarding NOM chemistry under simulated DGR conditions. Of particular concern is the possibility for gamma-radiation to alter NOM dissolution and reactivity due to the presence of reactive species generated by water radiolysis in Wyoming-type bentonites. In this study, NOM chemistry was investigated using complementary molecular-level techniques following exposure to a total gamma-radiation dose of 100 kGy (1.08 kGy/h for 93 h) at varied moisture levels (20%, 40%, 60% and 80%) and room temperature. Treated samples exhibited relatively low total organic carbon concentrations (0.074–0.232%), with no evidence of any major changes in total, organic, and inorganic carbon concentrations. Solid-state 13C NMR spectroscopy detected no changes in solid-phase NOM chemistry after irradiation. Solubilization of NOM increased significantly with radiation exposure at 80% moisture, suggesting higher levels of water saturation may enhance dissolved organic matter (DOM) production. Solution-state 1H nuclear magnetic resonance (NMR), and UV–Vis analyses did not identify any significant differences in DOM composition. More sensitive, targeted compound analysis revealed significant decreases in total n-alkanol concentration at lower moisture content levels (20% and 40%). Several individual compound concentrations also differed significantly at the nanogram-level, including n-octacosanol and several n-alkanoic acids at elevated moisture levels (60% and 80%). These findings suggest the majority of NOM in MX-80 remains chemically stable under the anticipated initial conditions of the proposed DGR.

Volatile Organic Compounds (VOCs) in Mediterranean Oak Forests of Hungarian Oak (Quercus frainetto Ten) Affected by Dieback Phenomena

In recent years, long periods of drought and heat waves have become increasingly frequent, causing forest dieback phenomena that make stands more sensitive to biotic stressors. How trees may respond to extreme climatic events and which metabolites are involved under stress conditions is still not clear. In this study, using Solid Phase Micro-Extraction (SPME)-GC/MS, we analysed how dieback (D) and non-dieback (ND) Hungarian oak trees from the San Paolo Albanese site respond to these climatic dynamics, focusing on volatile organic compounds (VOCs). For each group of trees, three wood samples were taken, and each was divided into four sub-samples with five growth rings and subjected to SPME and increase in basal area (BAI) analysis of the last 20 years. Dieback trees had a lower number of leaves, and this condition may translate into less photosynthesis, less organic matter production, and lower reserves of carbohydrates being available for growth. Indeed, D trees showed lower radial increases and a lower content of aldehydes, terpenes, and fatty acids than ND trees, indicating a better health of ND trees compared to D trees. Meanwhile, D trees showed a reduction in terpenes, such as α-pinene, γ-eudesmol, and cyperene (with significant insecticidal activity), a reduction in aromatic aldehydes, such as furfural and 5-methylfurfural, and an increase in silanols (with antimicrobial function). Considering the different compounds’ contents between D and ND trees, our study could be useful for detecting bio-indicators to identify an early warning signal of dieback phenomena.

Vermicompost Supply Enhances Fragrant-Rice Yield by Improving Soil Fertility and Eukaryotic Microbial Community Composition under Environmental Stress Conditions.

Heavy-metal contamination in agricultural soil, particularly of cadmium (Cd), poses serious threats to soil biodiversity, rice production, and food safety. Soil microbes improve soil fertility by regulating soil organic matter production, plant nutrient accumulation, and pollutant transformation. Addressing the impact of Cd toxicity on soil fungal community composition, soil health, and rice yield is urgently required for sustainable rice production. Vermicompost (VC) is an organic fertilizer that alleviates the toxic effects of Cd on soil microbial biodiversity and functionality and improves crop productivity sustainably. In the present study, we examined the effects of different doses of VC (i.e., 0, 3, and 6 tons ha-1) and levels of Cd stress (i.e., 0 and 25 mg Cd kg-1) on soil biochemical attributes, soil fungal community composition, and fragrant-rice grain yield. The results showed that the Cd toxicity significantly reduced soil fertility, eukaryotic microbial community composition and rice grain yield. However, the VC addition alleviated the Cd toxicity and significantly improved the soil fungal community; additionally, it enhanced the relative abundance of Ascomycota, Chlorophyta, Ciliophora, Basidiomycota, and Glomeromycta in Cd-contaminated soils. Moreover, the VC addition enhanced the soil's chemical attributes, including soil pH, soil organic carbon (SOC), available nitrogen (AN), total nitrogen (TN), and microbial biomass C and N, compared to non-VC treated soil under Cd toxicity conditions. Similarly, the VC application significantly increased rice grain yield and decreased the Cd uptake in rice. One possible explanation for the reduced Cd uptake in plants is that VC amendments influence the soil's biological properties, which ultimately reduces soil Cd bioavailability and subsequently influences the Cd uptake and accumulation in rice plants. RDA analysis determined that the leading fungal species were highly related to soil environmental attributes and microbial biomass C and N production. However, the relative abundance levels of Ascomycota, Basidiomycota, and Glomeromycta were strongly associated with soil environmental variables. Thus, the outcomes of this study reveal that the use of VC in Cd-contaminated soils could be useful for sustainable rice production and safe utilization of Cd-polluted soil.

Enhancing immobilized Chlorella vulgaris growth with novel buoyant barium alginate bubble beads

Microalgae immobilization in alginate beads shows promise for biomass production and water pollution control. However, carrier instability and mass transfer limitations are challenges. This study introduces buoyant barium alginate bubble beads (BABB), which offer exceptional stability and enhance Chlorella vulgaris growth. In just 12 days, compared to traditional calcium alginate beads, BABB achieved a 20 % biomass increase while minimizing cell leakage and simplifying harvesting. BABB optimization involved co-immobilization with BG-11 medium, enrichment of CO2 in internal bubbles, and the integration of Fe nanoparticles (FeNPs). In the open raceway pond reactor, these optimizations resulted in a 39 % increase in biomass over 7 days compared to the unoptimized setup in closed flasks. Furthermore, enhancements in pigment and organic matter production were observed, along with improved removal of ammonia nitrogen and phosphate. These results highlight the overall advantages of BABB for microalgae immobilization, offering a scientific foundation for their effective utilization.

Synechococcus sp. PCC7335 responses to far-red enriched spectra and anoxic/microoxic atmospheres: Potential for astrobiotechnological applications

Recently, cyanobacteria have gained attention in space exploration to support long-term crewed missions via Bioregenerative Life Support Systems. In this frame, cyanobacteria would provide biomass and profitable biomolecules through oxygenic photosynthesis, uptaking CO2, and releasing breathable O2. Their growth potential and organic matter production will depend on their ability to photoacclimate to different light intensities and spectra, maximizing incident light harvesting. Studying cyanobacteria responses to different light regimes will also benefit the broader field of astrobiology, providing data on the possibility of oxygenic photosynthetic life on planets orbiting stars with emission spectra different than the Sun. Here, we tested the acclimation and productivity of Synechococcus sp. PCC7335 (hereafter PCC7335), capable of Far-Red Light Photoacclimation (FaRLiP) and type III chromatic acclimation (CA3), in an anoxic, CO2-enriched atmosphere and under a spectrum simulating the low energetic light regime of an M-dwarf star, also comparable to a subsuperficial environment. When exposed to the light spectrum, with few photons in the visible (VIS) and rich in far-red (FR), PCC7335 did not activate FaRLiP but acclimated only via CA3, achieving a biomass productivity higher than expected, considering the low VIS light availability, and a higher production of phycocyanin, a valuable pigment, with respect to solar light. Its growth or physiological responses of PCC7335 were not affected by the anoxic atmosphere. In these conditions, PCC7335 efficiently produced O2 and scavenged CO2. Results highlight the photosynthetic plasticity of PCC7335, its suitability for astrobiotechnological applications, and the importance to investigate biodiversity of oxygenic photosynthesis for searching life beyond Earth.