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The purpose of the study is the determination of heavy metals in soil samples and their circulation in the food chain. In this study, the correlation between the presence of heavy metals in agricultural soils and the quality preservation of wheat, specifically Triticum Aestivum and Triticum Durum, was investigated. The results indicate that over 85% of the samples contain a high presence of metals compared to Kosovar standards. Land surveying was conducted at distances ranging from 20 m to 400 m from the highway. The results for Pb at a distance from 20 m showed a value of 2.11 mg·kg-1, while Zn varied with a value of 5.12 mg·kg-1. However, the amount of heavy metals in agricultural soil is not sufficient to determine their risk in the food chain. The samples studied from the wheat varieties exhibited the accumulation of metals in the wheat cultivated in the studied soils. Some wheat samples showed high levels of heavy metals, with Pb varying significantly with a value of 1.99 mg·kg-1, and Cr with a value of 6.12 mg·kg-1. In this study, the circulation of soil metals such as Pb, Cd, Cr, Fe, Cu, Zn, and Mn was monitored. The study then continued with the monitoring of soil physicochemical parameters as indicators of soil quality, such as organic carbon. The results showed variations depending on the distance and its concentration. The maximum protein value varied at 11.9%, gluten at 22.8%, moisture at 11.4%, etc., especially for Triticum E. and Triticum D. wheat varieties. [ABSTRACT FROM AUTHOR]

Stream and floodplain restoration is a popular billion‐dollar industry in the United States, with many restorations being conducted to satisfy water pollution regulations and nutrient reduction goals. The long‐term efficacy of these restorations is, however, not well studied, and key soil metrics that can be used for performance assessments have not been developed. We evaluated a chronosequence of 12 restoration sites spanning an age range of 0–22 years to assess changes in denitrification rates and associated soil parameters. Restored versus unrestored reaches were compared for denitrification rate and functional gene nosZ, bulk soil δ15N, soil organic carbon (SOC), soil organic matter (SOM), bulk density, and soil moisture. Denitrification, SOM, SOC, and soil moisture were all found to increase with site age at restored sites, with the largest increase for the 10–22 age category. Bulk density decreased with time, with a significant decrease in restored floodplain soils. Bulk soil δ15N was highest immediately after restoration, decreased with restoration age, and was not positively correlated with denitrification. This may reduce its potential as a proxy for denitrification. Overall, this study reveals that selected soil metrics (SOC, SOM, soil moisture, and bulk density) could serve as a valuable proxy for denitrification and could help assess the denitrification effectiveness of floodplain restorations at the decadal time scales. Ideally, the soil metrics should be combined with other short‐term assessment measures, such as those for stream and groundwaters, for a robust performance assessment of restored floodplains. [ABSTRACT FROM AUTHOR]

Aim Methods Results Conclusion Composts made from food waste will soon become more widespread on the market thanks to the upcoming enforcement of the legal obligation to sort biowaste. Our experiment aims at improving knowledge on the short‐term effects of these composts on soils’ physicochemical properties and vegetable crops.Three composts with contrasting characteristics were tested: a 100% v/v green waste compost (C1), and two composts composed of 50% v/v food waste and 50% v/v green waste, one prepared directly on the soil (C2) and the other from a competing producer who have the French NFU 44‐051 (AFNOR NF U 44‐051, 2006) certification for an organic amendment (C3). They were applied at a rate of 100 t ha−1 (dry matter) on two cropped soils with contrasting textures. Soil‐and‐compost mixes and compost‐free soil were planted with lettuce, radish, and potato.Seventy‐four days after planting, composts improved some soil physicochemical properties. The compost‐amended soils had better saturated hydraulic conductivity (Ks, 1 10−3–2.5 10−3 cm s−1) than the compost‐free soil (0.5 10−3 cm s−1), and water‐stable aggregates were higher than the initial value in C3 soil, equal to it in C2 soil, and lower in C1 soil. pH, total nitrogen, and organic carbon increased in all compost‐amended soils. Food waste compost stimulated crop production. The yields (dry matter) of all three crops were two to three times higher in the two soils amended with food waste compost compared to unamended soil, whereas they decreased almost two times in the soil amended with green waste compost due to nitrogen immobilization. Trace metals (particularly Pb and Cd) added by the composts, although present in edible parts of the plants, did not exceed the European rules for trace metals.Thus, food waste composts have positive effects on soils and vegetable crops, and the higher their organic matter content, the higher these positive effects. [ABSTRACT FROM AUTHOR]

Understanding the vertical distributions of organic carbon (OC) is crucial for predicting and simulating the influences of soil units on the terrestrial carbon cycle. The OC in the fine earth fraction was calculated for the soil units Anthrosols, Cambisols, Fluvisols, Leptosols, and Regosols in the municipality of Ponte de Lima, Portugal, at depths of 0–30 cm, 0–100 cm, 0–200 cm, and 0–2590 cm. In the study area, over 40% of the OC is concentrated in the Regosol unit, followed by the Anthrosols with over 23% OC at all depths, and the Leptosols with over 22% OC at all depths. The soil units Cambisols and Fluvisols have a lower representation in the territory, with values below 1.5% and 6.5% respectively at all depths. The obtained results contribute to assessing the potential of the soil units present in the municipality to sequester CO2, promoting the development of carbon inventories and analyzing the distribution of OC through accurate and reliable estimates of current C reserves as an essential tool for analyzing and modeling the effects of different factors involved in the potential of soil OC sequestration. [ABSTRACT FROM AUTHOR]

The Peruvian Amazon has experienced large losses of forest cover due to changes in land use, contributing to increases in CO2 in the atmosphere. This study estimated the organic carbon content of forest soil in two forests "Ojos de Agua" and "El Quinillal" in the Central Huallaga of Peru, establishing three types of cover: (i) primary, (ii) intervened, and (iii) deforested. For this purpose, 24 plots of 100 m2 were established and samples were extracted at a depth of 0–20 cm. The effect of the type of forest cover on soil carbon (Organic Carbon‐SOC, Inorganic Carbon‐SIC, Saturated Carbon‐SC, Critical Carbon‐CC, Saturated Carbon Deficit‐SCD, and Organic Carbon‐OC) was analyzed by means of an Analysis of Variance, correlation. Likewise, the relationship between carbon (C) and soil properties was evaluated by principal component analysis and correlation network. The results indicated that the highest SOC averages were found in the primary forests of Ojos de Agua and El Quinillal with 3.54% and 2.51%. The lowest values were found in the deforested forests with 1.34% and 1.46%. The calculation of the saturated C levels of the soil showed an average of 28.63% ± 2.14% and the saturated carbon deficit of 26.63% ± 2.45%, whereas the critical threshold of C showed an average of 2.21% ± 0.18%. The highest SOC content found in the Ojos de Agua primary forest is due to the presence of dominant forest species such as Manilkara bidentata and Brosimum alicastrum. Likewise, the C deficit in the soils of the study area is very alarming because it is very close to saturation levels, especially in deforested forests. [ABSTRACT FROM AUTHOR]

Most organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age‐depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age‐dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep‐sea environments. Our results show that a simple first‐order kinetics model suffices for well‐mixed sediments and systems receiving pre‐processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer. Plain Language Summary: Animals inhabiting marine sediments mix particles and impact organic carbon degradation kinetics and degradation rates. Experiments and theory have shown that organic carbon reactivity declines as degradation progresses with time. However, most studies employ a constant reactivity. Here we couple an individual particle mixing model with age‐dependent reactivity and show that a constant reactivity model is adequate for well‐mixed sediments and for sediments receiving organic carbon that has already been degraded elsewhere. An age‐dependent reactivity model is needed for poorly mixed sediments receiving highly reactive organic carbon. Key Points: Age‐dependent organic carbon kinetics is coupled to a Lagrangian particle tracking modelOrganic carbon concentrations, reactivities and degradation rates in the bioturbated zone are presentedA simple first‐order (one‐G) model suffices for well‐mixed sediments and sediments receiving pre‐processed organic carbon [ABSTRACT FROM AUTHOR]

Investigating carbon (C), nitrogen (N) and phosphorus (P) contents and ecological stoichiometric characteristics in leaf litter from tropical rainforests is crucial for elucidating nutrient cycling and energy flow in forest ecosystems. In this study, a 60-ha tropical montane rainforest dynamic monitoring plot in Jianfengling, was selected as the research site and 60 subplots were selected for detailed study. Leaf litter was collected monthly throughout 2016, branches of similar height were placed atthe four corners of each sample square to support a nylon cloth (1 m x 1 m) with 1 mm apertures. The collected plant leaves were sorted, placed into envelopes, labelled, and transported to the laboratory and samples from various plant species were identified, resulting in a total of 107 samples collected and analyzed. For the 31 dominant species, the leaf litter had C, N and P contents of 312.71 ± 28.42, 4.95 ± 0.46 and 0.40 ± 0.03 g/kg, respectively. The C:N, C:P and N:P ratios were 63.61 ± 7.50, 790.91 ± 82.30 and 12.49 ± 1.00, respectively, indicating moderate variability. The C, N and P contents exhibited greater variability among the plant groups, indicating significant heterogeneity among the samples. In contrast, the data from the subplots exhibited less variability, highlighting significant homogeneity. Overall, the mean carbon, nitrogen and phosphorus contents in the leaf litter from tropical montane rainforests were lower than those observed at national and global scales. The N:P ratios in leaf litter below 14 indicated that nitrogen limited litter decomposition in Jianfengling. However, no significant correlations were observed between the C, N and P contents and their stoichiometric ratios in leaf litter and those in soil. The above results provide important reference data and scientific basis for the nutrient cycling and energy flow processes, and in the future, we can explore the limiting role and mechanism of nitrogen in the decomposition process of leaf litter. [ABSTRACT FROM AUTHOR]

The linear depolarization ratio (LDR) of backscattering is a key parameter for distinguishing particle types. The measured LDRs of smoke in previous studies are highly variable and different from each other. Existing research on smoke aerosols considers only the internal mixing state of the black carbon (BC) particle population either by ignoring the externally mixed organic carbon (OC) particle population or by evaluating the LDR of smoke aerosols using the results of individual particles rather than the particle population. The field‐measured LDR of smoke then becomes difficult to interpret properly. The recent prescribed forest burning experiment in China showed that the LDR of freshly emitted smoke varies between 0.0% and 20.1% in wavelength (λ) of 532 nm. Electron microscopy images also showed that coated BC and pure OC exist simultaneously in biomass burning aerosols. Therefore, this study evaluates the influence of various parameters on the LDR of smoke by considering the internal and external mixing states. The calculated LDRs of the smoke aerosols were found to vary between 0.0% and 28.2% when λ is equal to 532 nm. The calculation results indicate that the LDR of smoke is slightly influenced by BC, considerably affected by the externally mixed OC, and is essentially dominated by the latter's morphology and particle size distribution. High levels and rapid changes of LDR of smoke can be well explained by nonsphericity and particle size distribution of externally mixed OC. This study advances the research on the measurement and evaluation of the LDR of smoke aerosols. Plain Language Summary: The backscattering linear depolarization ratio (LDR) is dependent on the particle shape and composition and can be differed among diverse particle types. Previous studies have shown significant variation in measured LDRs of smoke in the literature without considering the external mixing state of the particle population in the LDR calculations. We conducted the prescribed burning experiment in China, and measured the LDR of emitted smoke from biomass burning using lidar on site. Our measurement revealed wide and rapid variations in the LDR of newly emitted smoke. We used numerical simulations to calculate the LDR of the smoke particle population to interpret the measured results and those reported in the literature. Taking into account externally mixed ellipsoidal organic carbon (OC) particles, the smoke LDR is very sensitive to the size distribution and morphology of the externally mixed OC. The results can well explain the LDR of smoke in the field observations. This study generates useful information for the accurate measurement and assessment of the LDR of smoke. Key Points: The impact of externally mixed ellipsoidal OC on the bulk LDR was theoretically studied for the first timeBoth external and internal mixing state of particle population were taken into account in the calculationThe quantifications well explain the observation trends both in the literature and in our recent field measurement [ABSTRACT FROM AUTHOR]

The paper presents the results of studies aimed at assessing the variability of respiratory activity of soil microbiota (rates of basal and substrate-induced respiration), as well as of the content of organic matter carbon and microbial biomass carbon in soils formed and functioning in natural (slightly damaged) biogeocenoses along altitudinal gradient from the foothills to the high mountain regions of the Central Caucasus (500–3500 m a.s.l., Elbrus variant of altitudinal zonality, Kabardino-Balkaria). It is shown that the mean values of the studied indicators in surface horizons (0–10 and 0–20 cm, depending on the soil type) significantly increase with the altitude from mountain chernozems to subalpine mountain-meadow soils and significantly decrease at the maximum altitude in the zone of alpine mountain-meadow soils. The studied indicators in different soil types within the same altitudinal zone also differ; this difference is statistically significant (t > 2.5; p < 0.02) for most of the indicators for the compared pairs of soil types. The data obtained indicate that the impact of the altitudinal gradient is significantly transformed by additional factors. The multi-regression analysis has been performed to identify the effect of the main factors of relief (elevation above sea level and slope aspect and steepness) and climate (19 bioclimatic characteristics) on the studied indicators. It shows that the mean cumulative contribution of all 22 factors to the variation of the studied indicators is 40% in mountain chernozems, 66% in mountain-meadow chernozem-like soils, 31% in mountain meadow-steppe subalpine soils, 67% in subalpine mountain-meadow soils, and 67% in alpine mountain-meadow soils. Thus, the effect of the considered factors may significantly differ both for soils located along the altitudinal gradient and for soils functioning within the same altitudinal zone. Relief and climate play an important, but not the only, role in the formation of properties of mountainous soils in the Central Caucasus. [ABSTRACT FROM AUTHOR]

Measurement of hydraulic conductivity (HC) in the field and laboratory is time-consuming, laborious, and expensive, pedo-transfer functions can be used to predict the soil HC using easy-to-measure soil properties like bulk density (BD), soil texture, fractal dimension (D), organic carbon (OC) and glomalin content. In this study, 121 soil samples were used to predict HC using Multi Linear Regression, and four machine learning-based models i.e., Artificial Neural Network (ANN), Support Vector Machine (SVM), Classification and Regression Trees (CART) and Random Forest (RF). Two sets of input data were used i.e., dataset 1: texture data, BD, OC, and glomalin content and dataset 2: D, BD, OC, and glomalin content (Dataset 2). The models were evaluated based on Mean Absolute Error, Mean Absolute Percentage Error, Nash–Sutcliffe model efficiency, Root Mean Square Error (RMSE), and correlation coefficient. ANN with three hidden layers performed significantly for both input sets. The RMSE value was decreased by 17% in the training dataset and by 5.55% in the testing dataset when D was added to the input set for ANN. For both datasets, RF performed better and outperformed CART in predicting HC. According to the results, SVM with dataset 2 outperformed all other models which showed the inclusion of D in the dataset could predict HC more efficiently. However, further study is required for different combinations of datasets for evaluating the prediction efficiency of machine learning models for various regions. [ABSTRACT FROM AUTHOR]

The Thermal Evolved Gas Analyzer (TEGA) analysis of surface and icy subsurface Phoenix landing site soils consisted of low (300–700°C) and high (>700°C) temperature CO2 evolutions that were attributed to organic carbon (83–1,484 μgC/g) and Ca‐rich carbonate (1.1–2.6 wt.%). Total carbon abundances ranged from 1,143 to 4,905 µgC/g, which is the highest soil carbon concentration so far detected on Mars. Low temperature CO2 was attributed to oxidized organic C (e.g., oxalates, acetates), while hydrocarbon combustion was indicated in two soils by the detection of coevolved CO2 and O2 (perchlorate). Combustion reactions may have prevented the detection of hydrocarbon masses in the Phoenix landing site soils. Organic C was likely derived from meteoritic and igneous/hydrothermal sources, but microbiological sources cannot be excluded. CO2 evolved at high temperatures was consistent with Ca‐rich carbonate along with possible minor contributions from macromolecular organic carbon and mineral/glass vesicle CO2. Carbon detected in the Phoenix landing site soil and other landing site soils and sands (e.g., Gale/Jezero craters) would be consistent with global organic C and carbonate in soils and sand across Mars. However, oxidizing water thin films derived from the near‐surface ice in the Phoenix soils favor Ca‐carbonate over Fe‐carbonate, which is likely more stable in the ice‐free regions of Mars (e.g., Gale/Jezero craters). The global carbon budget on Mars inferred from these results emphasizes that Mars Sample Return should yield carbon bearing soil/rock that would allow the identification of the origin of carbon and any possible connections to ancient martian microbiology. Plain Language Summary: The Phoenix Lander's Thermal Evolved Gas Analyzer (TEGA) analyzed surface and subsurface icy soils of the martian northern plains in 2008. The TEGA instrument heated scooped soils to 1,000°C and measured evolved gases (e.g., CO2, O2, H2O) to quantify the presence of volatile bearing phases (e.g., organics, carbonates, salts). Some TEGA results have been previously published; however, this report describes unreported TEGA results. The TEGA instrument detected low (300–700°C) and high (>700°C) temperature CO2 evolutions that were attributed to organic carbon and Ca‐rich carbonate. Total carbon abundances as high as 4,905 µgC/g were detected which is the highest soil carbon concentration detected on Mars to date. Organic C sources include meteoritic and igneous/hydrothermal sources, but microbiological origins cannot be excluded. Ca‐rich carbonate may have been inherited from local sediments or was derived from dissolved CO2 reactions with the soil in migrating water thin‐films from subsurface ice. The carbon detections at the Phoenix and other landing sites suggest that Mars Sample Return of surface soil/rock should contain carbon that can be used to identify the origin(s) of carbon. Key Points: Phoenix landing site soils have the highest soil carbon concentration (up to 4,905 µgC/g) of any soil measured on MarsOrganic C (83–1,484 μgC/g) was likely derived from meteoritic sources with possible contributions from igneous/hydrothermal sourcesCa‐carbonate (1.1–2.6 wt.%) was inherited from local sediments or derived from soil reactions with dissolved CO2 in water thin‐films [ABSTRACT FROM AUTHOR]

We adopted a simple and rapid measurement method to analyze the concentrations of monosaccharides (MCHO) and polysaccharides (PCHO) in carbohydrates, a subset of organic carbon found in size-fractionated atmospheric particles. Seasonal and source-related factors influenced carbohydrate concentrations, with total water-soluble carbohydrates (TCHO) accounting for approximately 23% of the water-soluble organic carbon (WSOC) in spring when biological activity was high. We observed that the mode of aerosol transport significantly influenced the particle size distribution of carbohydrates, with MCHO exhibiting relatively high concentrations in fine particles (<1 μm) and PCHO showing higher concentrations in coarse particles (>1 μm). Moreover, our results revealed that MCHO and PCHO contributed 51% and 49%, respectively, to the TCHO concentration. This contribution varied by approximately ±19% depending on the season, suggesting the importance of both MCHO and PCHO. Additionally, through the combined use of principal component analysis (PCA) and positive matrix factorization (PMF), we determined that biomass burning accounts for 30% of the aerosol. Notably, biomass burning accounts for approximately 52% of the WSOC flux, with MCHO accounting for approximately 78% of the carbon from this source, indicating the substantial influence of biomass burning on aerosol composition. The average concentration of TCHO/WSOC in the atmosphere was approximately 18%, similar to the marine environment, reflecting the relationship between the biogeochemical cycles of the two environments. Finally, the fluxes of MCHO and PCHO were 1.10 and 5.28 mg C m−2 yr−1, respectively. We also found that the contribution of atmospheric deposition to marine primary productivity in winter was 15 times greater than that in summer, indicating that atmospheric deposition had a significant impact on marine ecosystems during nutrient-poor seasons. Additionally, we discovered that WSOC accounts for approximately 62% of the dissolved organic carbon (DOC) in the Min River, suggesting that atmospheric deposition could be a major source of organic carbon in the region. [ABSTRACT FROM AUTHOR]

Metabolism in stream ecosystems alters the fate of organic carbon (OC) received from surrounding landscapes, but our understanding of in‐stream metabolic processes in boreal ecosystems remains limited. Determining the factors that regulate OC metabolism will help predict how the C balance of boreal streams may respond to future environmental change. In this study, we addressed the question: what controls OC metabolism in boreal headwater streams draining catchments with discontinuous permafrost? We hypothesized that metabolism is collectively regulated by OC reactivity, phosphorus availability, and temperature, with discharge modulating each of these conditions. We tested these hypotheses using a combination of laboratory experiments and whole‐stream ecosystem metabolism measurements throughout the Caribou‐Poker Creeks Research Watershed (CPCRW) in Interior Alaska, USA. In the laboratory experiments, respiration and dissolved OC (DOC) removal were both co‐limited by the supply of reactive C and phosphorus, but temperature and residence time acted as stronger controls of DOC removal. Ecosystem respiration (ER) was largely predicted by discharge and site, with some variance explained by gross primary production (GPP) and temperature. Both ER and GPP varied inversely with watershed permafrost extent, with an inverse relationship between temperature and permafrost extent providing one plausible explanation. Our results provide some of the first evidence of a functional response to permafrost thaw in stream ecosystems and suggest the role of metabolism in landscape C cycling may increase as climate change progresses. Plain Language Summary: Rivers and streams can transform organic matter received from the surrounding landscape through the metabolic activity of microbes and other organisms. In boreal streams, little is known about ecosystem metabolism and whether respiration rates might change as warming‐induced permafrost thaw progresses. To understand if and how permafrost thaw is affecting stream microbial activity, we compared respiration rates in streams draining areas with different amounts of permafrost and used lab experiments to test which factors are currently limiting microbial activity. We found that metabolic rates were greatest in streams where the most permafrost thaw had occurred. This pattern could be explained by warmer water temperature promoting faster rates of microbial activity and less flashy flow conditions allowing more time for microbes to break down organic matter before it is flushed downstream. This newly documented relationship between permafrost thaw and stream respiration should be considered in efforts to better incorporate in‐stream processes into broader carbon cycling models. Key Points: Stream ecosystem respiration increased with permafrost thaw, likely due to warmer temperature and a more stable flow regimeWithin individual streams, ecosystem respiration was positively correlated with both discharge and gross primary productionRespiration was most limited by temperature and residence time in lab experiments, with additional co‐limitation by carbon and phosphorus [ABSTRACT FROM AUTHOR]

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Purpose: The information about mercury (Hg) fractions obtained by simple thermodesorption screening techniques has not been compared with that from chemical extraction methods. Here, we examined Hg fractions in the surface sediments by a simple thermodesorption method and by a sequential selective extraction method to better understand the biogeochemical reactivity and mobility of Hg in the Changjiang Estuary wetlands. Materials and methods: The concentrations of Hg fractions in sediments were analyzed by DMA-80 at different heating temperatures of 175, 225, 325 and 750 °C. Hg compounds in selected sediments were determined by sequential chemical extractions with 0.5 M HCl followed by 1 M KOH. Results and discussion: The results showed that the proportions of labile Hg fractions released at 175 ℃ were less than 5% of the total Hg, which could correlate with highly reactive and poorly crystalline iron oxides that have high biogeochemical reactivity in sediments. Furthermore, more than 74% (of the total, on average) of Hg in the sediments was released at temperatures between 175 and 325 ℃, which corresponded well to the amount of organic-chelated Hg in the sediments as determined by extraction with 1 M KOH. These results suggested that Hg bound to humic substances or to organomineral complexes could play a key role in controlling the thermal release of different Hg species from the sediments. Conclusions: The thermal decomposition method could serve as a fast and reliable screening method for the identification of different Hg compounds to help assess Hg mobility and bioavailability in aqueous (e.g., estuarine wetlands) sediments. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: A major function of mangroves is carbon sequestration in sediment. This study aimed to determine differences in carbon content in sediments in various types of mangroves and environmental parameters. METHODS: This study was carried out in Pesawaran as a natural mangrove and in South Lampung as rehabilitated mangrove in Indonesia. Purposive sampling method was used by considering the types of mangroves at the locations. Sediment sampling was taken using a polyvinyl chloride pipe with a diameter of 47.46 milimeters and a height of 30 centimeters. The sediment parameters measured were bulk density, carbon stock, and sequestration. Environmental parameters measured included sediment texture, potential of hydrogen, temperature, salinity, and total dissolved solids. A statistical analysis was conducted using the principal component analysis to determine the relationship between the organic carbon stock and the environmental parameters. FINDINGS: The study results showed that natural mangroves (Pesawaran) had a higher organic carbon value at 2.2 ± 0.32 percent than rehabilitated mangroves (South Lampung) at 0.9 ± 0.25 percent. The principal component analysis results revealed that organic carbon, carbon dioxide equivalent, carbon stock, and carbon sequestration had positive correlation characteristics influenced by salinity, silt, and clay, while negative correlation characteristics were affected by temperature, total dissolved solids, and sand. The distribution of sediment texture tended to show more silt in rehabilitated mangroves, while natural mangroves tended to have the same composition between sand and silt. The potential of hydrogen conditions in natural and rehabilitated mangroves showed no significant differences in values. The salinity in Pesawaran, which was classified as a natural mangrove, was higher due to the influence of the tides and was directly facing the shoreline. Meanwhile, in South Lampung, which was categorized as a rehabilitated mangrove, the salinity was lower due to the long dry season and the canals being unable to support the water entering the mangroves. CONCLUSION: The organic carbon content at the research locations was influenced by the older age of the Rhizophora stylosa compared to that of the Rhizophora mucronata and Ceriop tagal types of mangroves. The carbon sequestration rate values showed 1.65-3.14 for natural mangroves and 0.29-1.25 for rehabilitated mangroves, thus establishing that the rate is higher (2-3 times) in natural mangroves than in rehabilitated mangroves. [ABSTRACT FROM AUTHOR]

The coral reef ecosystem is one of the most productive ecosystems in the ocean, and is also an important calcium carbonate deposition region. Because excess production is very low in coral reefs, organic carbon reservoirs are very limited. During the calcification process, each mole of CaCO3 will produce 1 mol of CO2, approximately 60% of which will be released into the atmosphere through the sea-air interface. This causes coral reefs to be large inorganic carbon reservoirs, but at the same time, most coral reefs act as atmospheric CO2 sources (which also act as sinks in some coral reefs). Therefore, clarifying the sea-air CO2 exchange flux and carbon storage is critical for understanding the carbon cycle in coral reef ecosystems. In this paper, we summarize the carbon cycle processes in the coral reefs of the South China Sea (SCS) and estimate the total CO2 budget and carbon reserves. According to current research, the coral reefs in this area act as a source of atmospheric CO2, releasing 0.37-1.59 × 1011 g C a-1 into the atmosphere. Owing to their extremely high biological productivity and carbonate productivity, the carbon reserves of coral reefs in the SCS range from 1.66-3.78 × 1012gCa-1, which is an order of magnitude greater than the CO2 emissions at the sea-air interface. Overall, coral reefs in the SCS are important carbon storage areas. As the current results are still approximate, a more comprehensive and indepth investigation is needed to clarify the carbon source/sink processes, regulatory mechanisms, and carbon storage capacity of SCS coral reefs. [ABSTRACT FROM AUTHOR]

Introduction: Bottom sediments play a pivotal role in wetland productivity, and here, eight Gangetic floodplain wetlands of India were studied to assess the sediment physicochemical characteristics and textural analysis. Methods: Sediment samples that were collected from each wetland in monsoon and non-monsoon seasons were analysed. ANOVA, Principal component analysis and multiple correlation analysis were used for statistical analysis. Results and Discussion: Throughout the study period, pH (6.90-8.04), EC (0.20-1.64 dS/m), CaCO3 (1.75%-14.50%), available nitrogen (10.22-22.23 mg/ 100 g sediment), total nitrogen (80.4-333.8 mg/100 g sediment), available phosphorus (0.20-5.61 mg/100 g sediment), and total phosphorus (19.63-173.33 mg/100 g sediment) were recorded. The sediment quality parameters differ significantly (p > 0.05) among the wetlands. Seasonal variation was only observed on total nitrogen and total phosphorus contents. Sediments were dominated by sand. Sediment nutrient (C, N, and P) stoichiometry of wetlands depicted a comparatively little higher C/P (5.96-66.32) ratio and lower C/N (3.34-22.76) and N/P (1.12-9.25) ratios, which revealed that the physicochemical characteristics of the sediments are influenced by anthropogenic sources. Principal component analysis showed the influence of both natural and anthropogenic causes on wetland ecosystems. The geographic information system (GIS) interpolation approach was used in combination with laboratory analysis methods to give a complete spatial resolution of the sediment quality of each wetland. The study suggests that these wetlands' sediment quality is favorable for fish culture but requires proper management practices to achieve sustainable production. As it is the first time where monitoring physicochemical properties of sediments of these wetlands are presented, this study can be used as a baseline data for comparison in future environmental assessments of the wetlands. [ABSTRACT FROM AUTHOR]

Four hundred and sixty-six references with 625 data reports were included in our study. The high frequency of ratio OC/EC for PM0.1 was observed in 3.92–5.93; PM1 in 1.08–3.08; PM2.5, 2.08–4.08; PM10 in 2.70–4.70 and TSP in 2.66–4.66. The rank order of areas based on the pooled concentration of OC bound to PM2.5 was traffic (17.893 µg/m3) > industrial (10.58 µg/m3) > urban (7.696 µg/m3) > rural (4.08 µg/m3). The rank order of areas based on the pooled (mean) concentration of EC in PM2.5 was traffic (17.893 µg/m3) > industrial (2.65 µg/m3) > Urban (1.48 µg/m3) > rural (1.06 µg/m3). The pooled concentrations of OC and EC bound to PM2.5 in traffic areas were higher than in other areas. Therefore, it is recommended that monitoring and effectively reducing concentration plans are carried out, especially in traffic areas. [ABSTRACT FROM AUTHOR]

Straw return is an effective measure to increase soil sustainability. However, few studies have examined the effects of different straw return methods on soil structure, soil organic carbon content and maize yield or the potential relationships between those variables. Therefore, we developed a field orientation experiment to study the effects of different straw return methods on soil porosity, soil aggregate stability, the soil organic carbon content and maize yield. Four treatments were established: flat no-tillage with full straw mulching (FM), ridge no-tillage with full straw mulching (LM), rotary tillage with full straw incorporation (LX), and conventional tillage without straw (CK) as the control treatment. Compared with those of the CK treatment, the soil porosities (f) in the FM, LM and LX treatments significantly increased by 6.7%, 8.8% and 7.9%, respectively; the soil aggregate destruction rates (PAD) decreased by 17.3%, 34.3% and 16.9%, respectively. In addition, the FM, LM and LX treatments effectively increased the mean mass diameters (MWDs) of the soil aggregates and the soil organic carbon content. Compared with those in the CK treatment, the three-year average yields in the FM, LM and LX treatments significantly increased by 5.2%, 7.2% and 4.1%, respectively. Moreover, the f, MWD, soil organic carbon content and corn yield were positively correlated. Our study indicates that the LM treatment was most effective in improving soil structure and increasing soil organic carbon content with corn yield. [ABSTRACT FROM AUTHOR]

The content and distribution of precious metals in fine-grained bottom sediments, accumulated in the technogenic period (last decades) in the southwestern part of the Chukchi Sea, have been studied. The ubiquitous or local enrichment of the sediments with silver, gold, platinum, and palladium according to the average for the Earth's crust, as well as their enrichment with gold and palladium relative to pre-technogenic (Late Holocene) deposits, was shown. Differences in the conditions of the accumulation of precious metals in the Late Holocene and modern sediments were shown. Sources of input were determined, and the possibility of technogenic enrichment of the sources was proved by the methods of multicomponent statistical analysis of the total chemical composition of the sediments. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On low-lying soils with a high clay content and poor water conductivity, excess water regularly appears after almost every rainy winter causing soil degradation, which leads to yield failures and/or losses. To outlet the harmful excess surface, waters needs appropriate ameliorative and agrotechnical operations. Among them, scraping represents a suitable intervention into soil structure involving the complete conversion of the micro-topography of the land. The humus content of the soil is a determining factor in terms of soil fertility; therefore, it must be preserved even when drastic tillage operations are carried out on a plot. Our research aimed to assess the effect of scraping on the humus content of the soil on three plots with a heavy textured Vertisol endangered by excess waters. Scraping was used on these plots to create a homogeneous topography and surface with a slight slope to get rid of excess water when it appears. It was established that scraping did not cause humus loss on a plot scale, and it resulted in an evener organic matter distribution, hence a potentially more homogenous yield within the ameliorated plots. [ABSTRACT FROM AUTHOR]

Iron–carbon galvanic-cell-supported autotrophic denitrification (IC-ADN) is a burgeoning efficient and cost-effective process for low-carbon wastewater treatment. This study revealed the influence of organic carbon (OC) and dissolved oxygen (DO) on IC-ADN in terms of functional and microbiological characteristics. The nitrogen removal efficiency increased to 91.6% and 94.7% with partial organic carbon source addition to COD/TN of 1 and 3, respectively. The results of 16S rRNA high-throughput sequencing with nirS and cbbL clone libraries showed that Thiobacillus was the predominant autotrophic denitrifying bacteria (ADB) in the micro-electrolysis-based autotrophic denitrification, which obtained nitrogen removal efficiency of 80.9% after 96 h. The ADBs shifted gradually to heterotrophic denitrifying bacteria Thauera with increasing COD/TN ratio. DO concentration of 0.8 rarely affected the denitrification efficiency and the denitrifying communities. When the DO concentration increased to 2.8 mg/L, the nitrogen removal efficiency decreased to 69.1%. These results demonstrated that autotrophic denitrification was notably affected by COD/TN and high DO concentration, which could be used to acquire optimum conditions for nitrogen removal. These results provided an in-depth understanding of the influential factors for galvanic-cell-based denitrification and helped us construct a stable and highly efficient treatment process for insufficient carbon source wastewater. [ABSTRACT FROM AUTHOR]

The aerosols play a main role in precipitation formation in the atmosphere. Organic Carbon (OC) is a must-imported aerosol because it is considered a cloud condensation nuclear CCN. This work dealt with the relationship between Organic Carbon (OC) and many variables that affect precipitation formation in South Iraq (Basra and AL-Muthana) including Cloud Top Temb Cloud Top Temperature CTT, Total PrecipitableWater TPW, and Precipitation. The cases selected are 14 – 15 Nov. 2018 and 26 – 29 Jan. 2019 to test the relationship between variables. Data obtained from retrospective analysis for research and applications, version 2 (MERRA-2). Including OC, total Precipitablewater (TPW), and precipitation amount of 3 hours. The times are fixed according to the cases. The cloud top temperature (CTT) was obtained by the infrared satellite images provided by the European Space Agency, using a group of satellites. The result indicates a strong effect of OC on the cloud depth and the TPW when finally increases the precipitation amount. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oil production facilities exercise severe technogenic impact on dry-steppe chestnut soils (Kastanozems) of the Tamsagbulag oilfield. This paper estimates the degree of soil contamination with petroleum hydrocarbons and mechanical disturbance of the soil cover. It has been established that technogenic impact on chestnut soils due to oil production is manifested in a high variability of physicochemical parameters in the surface horizon: aqueous extract mineralization varies from 32.5 to 325.0 mg/L; specific electrical conductivity, from 65.4 to 647.0 μS/cm; while concentration of hydrocarbons (HCs), from 7 to 647 mg/kg. Only in a few cases, HC concentrations exceed the background level established for oil production zones (100 mg/kg) by 3.2 and 6.5 times. The HC proportion in the total organic carbon content (Corg) varies in a wide range: from 0.01 to 6.20%. Gas chromatographic analysis of the molecular-weight distribution of n‑alkanes in the HC composition showed that high molecular weight (C27–C39) homologues with high enough transformation degrees of individual odd-numbered n-alkanes prevail in the surface soil horizon. The proportion of medium molecular weight homologues (∑C22–C25) does not exceed 8% of the total content of n-alkanes. In the soil microbial community, heterotrophic bacteria (HB) predominate among ecological–trophic groups of microorganisms (unicellular bacteria, actinomycetes, and micromycetes); the proportion of oil-oxidizing bacteria in the total HB count reaches 9.1–39.3%. Degradation of petroleum HCs is accompanied by the formation of a wide range of volatile organic compounds. The quantitative and qualitative composition of oil components in the surface horizon is determined by two processes: HC vertical migration and transformation. Together, these processes offset the accumulation of oil in the surface soil horizon. [ABSTRACT FROM AUTHOR]

Extended Abstract Background: Forest fire is very common in all ecosystems of the world that affects both vegetation and soil and is also helpful in maintaining the diversity and stability of ecosystems. The effect of forest fires and prescribed fires on forest soil is very complex. It affects the organic matter, macro and micronutrients, and physical properties of soil, such as texture, color, pH, and bulk density, as well as soil biota. Fire is a natural factor in the forest that temporarily reduces the vegetation on the soil surface. After a fire, the soil can experience long-term, medium-term, and short-term changes, which are different depending on the type of soil characteristics, weather conditions, duration, intensity, and frequency of the fire. The Zagros forest ecosystem is generally in the coppice form, and these forests are not safe from fire, which constantly affects them. Considering that the long-term stability of these forests depends on maintaining the soil quality, it is essential to investigate the effects of fire on soil properties. This study aimed to investigate the effect of fire on Zagros forests in Kermanshah province, Gahvareh city in the Lerini region. Methods: The studied area is a part of Zagros forests in Kermanshah province, Gahvareh city, the Lerini region located at 34° 10' 35″ E and 46° 34' 28″ N, with an average height of 1468 m above sea level. In this research, the points were determined by measuring with a meter on transects, and they were sampled regularly in specific time intervals (October, November, February, April, and June). The distance between the samples in each row was 20 m and the distance between the rows was 50 m, and three rows were determined in each of the burnt and control areas. Some soil characteristics, such as pH, electrical conductivity (EC), organic carbon, absorbable phosphorus, soil respiration, microbial biomass carbon, substrate-induced respiration, and metabolic quotient, were measured in soil samples. The effect of the treatments on all measured variables was investigated by the two-way ANOVA. Means were compared by Duncan’s Multiple Range Test (DMRT). Data were analyzed using the Windows version of SAS (version 9.4, SAS Institute Inc., Cary, NC). Results: The soil pH decreased with the passage of time and a decrease in air temperature under the crown (unburnt and burned) and outside the unburnt crown. An upward trend in the pH of the soil in these three places occurred after the cold season. The soil pH ranged from 7.31 to 7.66 in all treatments from October to June. The results of the two-way ANOVA showed that the fire and sampling location did not affect the soil EC in different months of sampling. The amount of absorbable phosphorus increased with the occurrence of fire. The highest and lowest amounts of absorbable phosphorus occurred under and outside the burnt and the control crowns, respectively. The range of organic carbon changes indicates that soil organic carbon has increased over time in all treatments. The highest and the lowest increases were observed under the burnt (1.51%) and the control (unburned) crowns, respectively. Examining the changes indicates that the basic soil respiration was high at the beginning of the fire but decreased gradually, and then the initial value also increased in the last months of sampling. In this research, the amount of basic respiration in the soil of burned areas is not higher than that of unburned areas despite the occurrence of fire and the negative effect on soil organic carbon. According to the results, the amount of substrate-induced respiration decreases under and outside the crown (burnt and control) with the passage of time and the decrease in temperature. According to the ANOVA results, the effects of fire and the sampling location were significant on the microbial metabolic quotient of the soil, although no significant interaction effects on the microbial metabolic quotient were observed in February and June. The highest and the lowest microbial metabolic quotients were measured under (0.94 mg C/mg MBC.day) and outside (0.26 mg C/mg MBC.day) the unburned crown, respectively. With the passage of time and a decrease in temperature, the amount of this parameter decreased in the treatment under the crown of the unburnt area and increased in the three treatments under and outside the burned crown and outside the unburnt crown. At the end of the period, the highest and the lowest microbial metabolic quotients were measured under (0.72 mg C/ mg MBC. day) and outside (0.59 mg C/ mg MBC. day) the crown of the burned area, respectively. Conclusion: The results showed that the fire was superficial in both places under and outside the crown and did not significantly affect the soil’s chemical and biological characteristics. Therefore, no significant changes occurred in indicators such as soil organic carbon and EC, and the fire only increased phosphorus in the burned areas compared to the control. Due to the occurrence of surface fire, combustion did not significantly increase biological indicators. The results of this research demonstrate that the fire changes the soil’s chemical and biological characteristics when it occurs with a higher intensity and at a higher temperature.

The purpose of the study is the determination of heavy metals in soil samples and their circulation in the food chain. In this study, the correlation between the presence of heavy metals in agricultural soils and the quality preservation of wheat, specifically Triticum Aestivum and Triticum Durum, was investigated. The results indicate that over 85% of the samples contain a high presence of metals compared to Kosovar standards. Land surveying was conducted at distances ranging from 20m to 400m from the highway. The results for Pb at a distance from 20 m showed a value of 2.11 mg·kg-1, while Zn varied with a value of 5.12 mg·kg-1. However, the amount of heavy metals in agricultural soil is not sufficient to determine their risk in the food chain. The samples studied from the wheat varieties exhibited the accumulation of metals in the wheat cultivated in the studied soils. Some wheat samples showed high levels of heavy metals, with Pb varying significantly with a value of 1.99 mg·kg-1, and Cr with a value of 6.12 mg·kg-1. In this study, the circulation of soil metals such as Pb, Cd, Cr, Fe, Cu, Zn, and Mn was monitored. The study then continued with the monitoring of soil physicochemical parameters as indicators of soil quality, such as organic carbon. The results showed variations depending on the distance and its concentration. The maximum protein value varied at 11.9%, gluten at 22.8%, moisture at 11.4%, etc., especially for Triticum E. and Triticum D. wheat varieties.

Abstract Maize cultivation is under the growing threat of charcoal rot (Macrophomina phaseolina). Chemical control of diseases imparts serious health hazards to humans and the ecosystem. Biochar as an alternative disease management approach has been under consideration of the researchers for some time now. The biochar utilized in this study was derived from maize stalks and cobs. Crystallographic structure, inorganic minerals content and size of maize biochar were analyzed by powder X-ray diffractometer, while scanning electron microscopy revealed rough, irregular, tubular structure of the biochar surface. EDX spectra revealed that the maize biochar composition was dominated by ‘C’ followed by ‘O’. The current study was designed to determine the synergistic effect of maize biochar (MB), and biocontrol agent (BCA) Trichoderma viride as soil amendments on the suppression of M. phaseolina. In vitro bioassays were conducted to check the efficiency of antagonistic effect of Trichoderma spp., in combination with maize biochar. On the basis of maximum mycelial growth inhibition T. viride was selected for a glasshouse experiment. Maize plants were grown in pots containing a mixture of soil with MB at application at the rate of 3 and 6% (v/v) separately, associated with or without T. viride. Treatments amended with 3% MB inoculated with M. phaseolina significantly reduced the percentage disease severity index by 40%. While in the presence of T. viride, 3% MB showed maximum disease suppression and a minimum percentage severity index i.e. 60 and 20%, respectively. Highest nitrogen contents were 18.4 g kg−1 observed in treatment 6% MB, while highest phosphorus and potassium contents were 3.11 and 15.2 g kg−1, respectively in the treatment with 3% MB. Conclusively, the effect of variable concentrations of maize biochar and T. viride as soil amendment was evident on the development of charcoal rot, growth and physiology of maize plants. According to the available literature, our report is the first on the implementation of biochar in synergism with T. viride to suppress the charcoal rot in maize.

Abstract Pesticide contamination and soil degradation present significant challenges in agricultural ecosystems, driving extensive exploration of biochar (BC) and nano-biochar (NBC) as potential solutions. This study examines their effects on soil properties, microbial communities, and the fate of two key pesticides: the hydrophilic methomyl (MET) and the hydrophobic lambda-cyhalothrin (LCT), at different concentrations (1%, 3%, and 5% w w−1) in agricultural soil. Through a carefully designed seven-week black bean pot experiment, the results indicated that the addition of BC/NBC significantly influenced soil dynamics. Soil pH and moisture content (MC) notably increased, accompanied by a general rise in soil organic carbon (SOC) content. However, in BC5/NBC5 treatments, SOC declined after the 2nd or 3rd week. Microbial populations, including total plate count (TPC), phosphate-solubilizing bacteria (PSB), and nitrogen-fixing bacteria (NFB), showed dynamic responses to BC/NBC applications. BC1/NBC1 and BC3/NBC3 applications led to a significant increase in microbial populations, whereas BC5/NBC5 treatments experienced a decline after the initial surge. Furthermore, the removal efficiency of both MET and LCT increased with higher BC/NBC concentrations, with NBC demonstrating greater efficacy than BC. Degradation kinetics, modeled by a first-order equation, revealed that MET degraded faster than LCT. These findings underscore the profound impact of BC/NBC on pesticide dynamics and microbial communities, highlighting their potential to transform sustainable agricultural practices.

Abstract Exposure assessments to metalworking fluids (MWF) is difficult considering the complex nature of MWF. This study describes a comprehensive exposure assessment to straight and water-based MWFs among workers from 20 workshops. Metal and organic carbon (OC) content in new and used MWF were determined. Full-shift air samples of inhalable particulate and gaseous fraction were collected and analysed gravimetrically and for metals, OC, and aldehydes. Exposure determinants were ascertained through observations and interviews with workers. Determinants associated with personal inhalable particulate and gaseous fractions were systematically identified using mixed models. Similar inhalable particle exposure was observed for straight and water-based MWFs (64–386 µg/m3). The gaseous fraction was the most important contributor to the total mass fraction for both straight (322–2362 µg/m3) and water-based MWFs (101–699 µg/m3). The aerosolized particles exhibited low metal content irrespective of the MWF type; however, notable concentrations were observed in the sumps potentially reaching hazardous concentrations. Job activity clusters were important determinants for both exposure to particulate and gaseous fractions from straight MWF. Current machine enclosures remain an efficient determinant to reduce particulate MWF but were inefficient for the gaseous fraction. Properly managed water-based MWF meaning no recycling and no contamination from hydraulic fluids minimizes gaseous exposure. Workshop temperature also influenced the mass fractions. These findings suggest that exposures may be improved with control measures that reduce the gaseous fraction and proper management of MWF.

Abstract Trait heritability and the response to selection depend on genetic variation, a prerequisite to developing sorghum varieties with desirable agronomic traits and high carbon sequestration for sustainable crop production and soil health. The present study aimed to assess the extent of genetic variability and associations among agronomic and carbon storage traits in selected sorghum genotypes to identify the best candidates for production or breeding. Fifty genotypes were evaluated at Ukulinga, Bethlehem and Silverton sites in South Africa during the 2022/23 growing season. The following agronomic and carbon storage traits were collected: days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), grain yield (GY), harvest index (HI), shoot carbon content (SCc), root carbon content (RCc), grain carbon content (GCc), total plant carbon stock (PCs), shoot carbon stock (SCs), root carbon stock (RCs), and root-to-shoot carbon stock ratio (RCs/SCs), and grain carbon stock (GCs). Higher genotypic coefficient of variations (GCVs) were recorded for GY at 45.92%, RB (39.24%), RCs/SCs (38.45), and RCs (34.62). Higher phenotypic coefficient of variations (PCVs) were recorded for PH (68.91%), followed by GY (51.8%), RB (50.51%), RS (41.96%), RCs/SCs (44.90%), and GCs (41.90%). High broad-sense heritability and genetic advance were recorded for HI (83.76 and 24.53%), GY (78.59 and 9.98%), PB (74.14 and 13.18%) and PCs (53.63 and 37.57%), respectively, suggesting a marked genetic contribution to the traits. Grain yield exhibited positive association with HI (r = 0.76; r = 0.79), DTH (r = 0.13; r = 0.31), PH (r = 0.1; r = 0.27), PB (r = 0.01; r = 0.02), RB (r = 0.05; r = 0.06) based on genotypic and phenotypic correlations, respectively. Further, the path analysis revealed significant positive direct effects of SB (0.607) and RB (0.456) on GY. The RS exerted a positive and significant indirect effect (0.229) on grain yield through SB. The study revealed that PB, SB, RB, RS, RCs, and RCs/SCs are the principal traits when selecting sorghum genotypes with high yield and carbon storage capacity.

Lakes are important carbon sinks in terrestrial ecosystems. Currently, most of lake carbon burial research in China only considers organic carbon burial and has neglected inorganic carbon burial, which will lead to an underestimation of the total carbon burial capacity of lakes. This situation is particularly significant in the humid eastern plain region. In order to comprehensively understand the carbon burial characteristics of lakes in the eastern plain and evaluate the contributions of organic and inorganic carbon burial to total carbon burial more reasonably. This research chooses Hongze Lake as study site, which is a representative lake in the eastern plain region. Based on the 210Pb-137Cs chronological sequence, combined with the C/N and δ13C characteristics in sediments, the carbon burial characteristics of Hongze Lake sediments in the past 60 years were explored by analyzing the spatiotemporal changes of organic and inorganic carbon content in typical rock cores (numbered HZH-12) and 11 other surface sediments. C/N and δ13C shows that endogenous organic carbon is the main source of organic carbon inHongze Lake . The significant synergistic changes in the accumulation rates of organic and inorganic carbon over the past 60 years (R2=0.76, p

【Objective】 Soil organic carbon (SOC) is not only an indicator of soil health but also plays a crucial role in feedback interaction between global warming and carbon stock in terrestrial ecosystems. Its dynamics is modulated by a multitude of interactive abiotic and biotic factors. In this paper, we analyze the spatial distribution of SOC in the plough layer and its correlation with soil texture and other geochemical properties in the region of Zhengzhou in Henan province. 【Method】 Soil samples were taken from a grid network in the region. SOC, bulk density, soil texture and other geochemical properties in each soil sample were measured. The correlation between SOC and soil nutrients, including nitrogen, phosphorus, potassium and micronutrients in the soil, was analyzed using the GeoChemStudio software. 【Result】 The calcareous skeletol soil in the region has the highest SOC, reaching 2.307%. The SOC content varied from 0.1%-11.6% across the region, and was normally distributed with a mean of 1.134%. The SOC was positively correlated with N, P2O5, Fe, Mn, Zn, Cu, Mo and B, and their associated correlation coefficients were 0.804 5, 0.223 0, 0.156 3, 0.119 1, 0.223 8, 0.263 4, 0.162 8 and 0.191 1, respectively. Negative correlations were found between SOC and K2O and pH, and their associated correlation coefficients were -0.088 8 and -0.195 7, respectively. The average SOC content in the plough layer in the region was 1.09%. Spatially, SOC was rich in Xinmi, Dengfeng and Gongyi in the southwest of the region. In terms of soil texture, SOC is higher in skeletol soil and calcareous cinnamon soil than in other soils. SOC stored in the topsoil in the whole region was 1 012.87×104 t, with 523.13×104 t stored in the cinnamon soils and calcareous cinnamon soils, accounting for 51.64% of the total topsoil SOC in the region.

The present study was conducted in monospecific stand of Cork oak (Quercus suber L.) in the Oulmes Central Plateau (Case of Zitchouene Forest), with the following objectives: the determination of the organic carbon stock in the different compartments of the forest ecosystem, namely: the soil, the above-ground and below-ground biomass. To achieve these objectives, we studied the biomass of the cork oak tree in the study area, using direct dry weight measurements on 30 sample trees". Furthermore, the volume of standing trees was estimated using a volume tariff based on direct measurements of circumference at 1.30 and total tree height, all of which allowed us to estimate the biomass expansion and conversion factor (BECF) specific to the Oulmes Central Plateau cork oak. As a result, the volume and above-ground biomass were estimated at 55.74 m3/ha and 20.13 t/ha of dry matter respectively. Soil organic carbon stock and biomass (above and below ground) were estimated at 43.02 t/ha and 16.60 t/ha, respectively. The BECF, determined by the ratio between volume and biomass, was 0.59, which approaches the minimum value recorded under the same productivity conditions estimated by the IPCC (0.6-1.4).

The study of soil physico-chemical properties is an important field related to the aspect of climate change and the storage of organic carbon in soil. This field of scientific research aims to identify the impact of land management practices on the physico-chemical parameters of soil composition. This study is based on laboratory analysis and various observations of various soil physicochemical parameters, such as pH-H2O, EC [electrical conductivity]; OM [organic matter]; SOC [% organic carbon]; SOC [SOC t/ha]; and BD [specific gravity g/cm3]. This study helps develop strategies to implement improved land management sustainably. The soil specific gravity (BD g/cm³) averages 1.38 g/cm³, with low variability (Std. Dev. = 0.03337), the coefficient of variation (CV) is 2.410378%, indicating a low variation about the mean, while the skewness is negative (-0.78464), while the kurtosis is positive (1.766186). Some of the differences (OM, SOC, SOC t/ha) have a high variability, while others have a lower variability (EC μS/cm, pH [1:2.5], BD g/cm³). This may indicate that some soil characteristics are more stable, while others have a higher degree of variability.

The Arctic rapidly warms and sea ice retreats, a large fraction of organic carbon (OC), currently stored in coastal permafrost will be released into the marine system. Once reintroduced into the active carbon cycle, this material will either be decomposed or buried on the shelf depending on its hydrodynamic and chemical properties. Currently, carbon estimates are based on bulk measurements, which does not take the hydrodynamic pathway of different fractions into account. Therefore, eight coastal permafrost locations have been sampled along the Canadian Beaufort Sea Coast, hydrodynamically fractionated and analyzed for their C, N, 13C and 14C content. We found that the matrix‐free fraction (low density <1.8 g/cm3, and high‐density >1.8 g/cm3; <38 μm) account for 77%–98% of the OC. By using a coastal classification combined with field data, our results showed that short coastal segments can become key players in delivering matrix‐free, easily degradable OC to the marine system. Plain Language Summary: Arctic coastlines consisting out of permafrost, permanently frozen ground, experience accelerated erosion due to rising global temperatures. This erosion poses a threat to local communities and releases thawed permafrost material into the Arctic Ocean. Permafrost coasts store significant amounts of organic carbon (OC), and as they thaw and erode, this carbon is released, impacting the climate through the potential release of CO2. Current estimates rely on bulk measurements, but the behavior of released OC in the ocean remains poorly understood. To address this, we used hydrodynamic fractionation on eight sampled coastal permafrost sites along the Canadian Beaufort Sea. By doing so we separate the material based on density and grain size. The results show that a significant portion of OC (77%–98%) falls into the low‐density and the high‐density fine (<38 μm) fraction, containing easily degradable plant‐rich material. Due to these two fractions short coastal segments can become key players for the delivery of degradable OC into the ocean. Key Points: Coastal types vary in size and density distribution, high‐density prevailing in weight and low‐density dominating organic carbon contentBetween 77% and 98% of eroded organic carbon resides in the matrix‐free fraction, prone to degradation and CO2 releaseHydrodynamic fractionation and site‐specific properties contribute to integration of results into land‐ocean flux models [ABSTRACT FROM AUTHOR]

Maize cultivation is under the growing threat of charcoal rot (Macrophomina phaseolina). Chemical control of diseases imparts serious health hazards to humans and the ecosystem. Biochar as an alternative disease management approach has been under consideration of the researchers for some time now. The biochar utilized in this study was derived from maize stalks and cobs. Crystallographic structure, inorganic minerals content and size of maize biochar were analyzed by powder X-ray diffractometer, while scanning electron microscopy revealed rough, irregular, tubular structure of the biochar surface. EDX spectra revealed that the maize biochar composition was dominated by 'C' followed by 'O'. The current study was designed to determine the synergistic effect of maize biochar (MB), and biocontrol agent (BCA) Trichoderma viride as soil amendments on the suppression of M. phaseolina. In vitro bioassays were conducted to check the efficiency of antagonistic effect of Trichoderma spp., in combination with maize biochar. On the basis of maximum mycelial growth inhibition T. viride was selected for a glasshouse experiment. Maize plants were grown in pots containing a mixture of soil with MB at application at the rate of 3 and 6% (v/v) separately, associated with or without T. viride. Treatments amended with 3% MB inoculated with M. phaseolina significantly reduced the percentage disease severity index by 40%. While in the presence of T. viride, 3% MB showed maximum disease suppression and a minimum percentage severity index i.e. 60 and 20%, respectively. Highest nitrogen contents were 18.4 g kg−1 observed in treatment 6% MB, while highest phosphorus and potassium contents were 3.11 and 15.2 g kg−1, respectively in the treatment with 3% MB. Conclusively, the effect of variable concentrations of maize biochar and T. viride as soil amendment was evident on the development of charcoal rot, growth and physiology of maize plants. According to the available literature, our report is the first on the implementation of biochar in synergism with T. viride to suppress the charcoal rot in maize. [ABSTRACT FROM AUTHOR]

Exposure assessments to metalworking fluids (MWF) is difficult considering the complex nature of MWF. This study describes a comprehensive exposure assessment to straight and water-based MWFs among workers from 20 workshops. Metal and organic carbon (OC) content in new and used MWF were determined. Full-shift air samples of inhalable particulate and gaseous fraction were collected and analysed gravimetrically and for metals, OC, and aldehydes. Exposure determinants were ascertained through observations and interviews with workers. Determinants associated with personal inhalable particulate and gaseous fractions were systematically identified using mixed models. Similar inhalable particle exposure was observed for straight and water-based MWFs (64–386 µg/m3). The gaseous fraction was the most important contributor to the total mass fraction for both straight (322–2362 µg/m3) and water-based MWFs (101–699 µg/m3). The aerosolized particles exhibited low metal content irrespective of the MWF type; however, notable concentrations were observed in the sumps potentially reaching hazardous concentrations. Job activity clusters were important determinants for both exposure to particulate and gaseous fractions from straight MWF. Current machine enclosures remain an efficient determinant to reduce particulate MWF but were inefficient for the gaseous fraction. Properly managed water-based MWF meaning no recycling and no contamination from hydraulic fluids minimizes gaseous exposure. Workshop temperature also influenced the mass fractions. These findings suggest that exposures may be improved with control measures that reduce the gaseous fraction and proper management of MWF. [ABSTRACT FROM AUTHOR]

In order to realize the rapid and quantitative monitoring of soil organic carbon content in farmland, nine conventional pretreatment analysis methods were used to optimize the original spectral information and analyze the relationship between each pretreatment spectrum and wheat soil organic carbon content, and the continuous projection algorithm (SPA) was used to extract the spectral characteristics of soil organic carbon, and two types of soil organic carbon spectral monitoring models based on full spectrum and spectral characteristic bands were established. The results showed that the correlation between the pretreatment spectrum and soil organic carbon in wheat could be significantly improved compared with the original spectrum. In the meantime, the SPA method was used to extract and confirm the important information of soil organic carbon content in the spectral regions of 400-450 nm, 510-620 nm, 1010-1 060 nm and 2 000-2 400 nm. Comparing the performance of the two types of models, it can be seen that the continuous projection algorithm-multiple linear regression (SPA-MLR) model is better than the partial least squares regression (PLSR) model under the same pretreatment spectra, and the overall performance of the soil organic carbon content estimation model based on multivariate scattering correction (MSC) pretreatment spectra is the best (Rv2=0.726, RMSEv=0.109, RPDv=1.956), and it has practical application potential. This study confirms that spectral pretreatment can improve the correlation between spectral reflectance and soil organic carbon content in wheat to a certain extent, and affect the performance of the monitoring model, and the model construction method may have a more positive effect on the accuracy of model estimation. The results of this study can provide a theoretical basis and practical exploration for the detection of soil organic carbon content in farmland. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems play a key role in the global carbon cycle by collecting, transporting, and processing a significant portion of global organic carbon. These processes can be disrupted in non-perennial rivers due to their changing hydrological patterns. We investigated how environmental factors influence organic matter dynamics in the Algars, a Mediterranean non-perennial river basin in the North-East Iberian Peninsula. We conducted seasonal sampling in 16 sites across the river network, collecting samples for (i) storage of benthic organic matter, (ii) transport of dissolved organic carbon and particulate organic matter, and (iii) organic matter processing via aerobic respiration in sediments (Raz–Rru method). We observed pronounced spatial and temporal fluctuations in organic matter processes, especially during distinct periods like summer and autumn. Consistent seasonal patterns of organic matter transport showed a remarkable longitudinal increase downstream, similar to observed aerobic respiration in sediments. Notably, high-flow events doubled observed seasonal transport (mean DOC load: 2344 ± 735 kg/day). Irregular spatial storage patterns between dry and wet channel sections were related to land use and flow intermittency. Notably, storage in dry channel sections was generally ten times higher than wet sections. Our study emphasizes the intricate influence of specific environmental variables on organic matter processes, within different organic matter fractions (for example, coarse and dissolved organic matter). Frequency of non-flow events, seasonal hydrological changes, and land use predominantly govern organic matter dynamics in the Algars basin. Understanding organic carbon dynamics in non-perennial systems will help estimate the impact of hydrological alterations associated with global change on river systems. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) has been one of the most important indicators for the soil quality and agricultural sustainability. Commonly-used models can generally require a large number of soil samples as training dataset in many cases, in order to predict the spatial distribution of SOC. However, the soil sampling is time-consuming, laborious and costly. Once only a limited number of soil samples is available, the existing models, such as multiple linear regression (MLR) and artificial neural networks (ANN), cannot well acquire the reliable relation between environmental variables and SOC, leading to the unsatisfactory prediction. In this study, an environmental similarity model (ESM) was proposed, according to the assumption that the more similar the soil forming environment was, the more similar the soil properties were. Three major steps were used to design the ESM: (1) To characterize the soil forming environment on the soil sampling and unvisited sites using key environmental variables that affected on the spatial distribution of SOC, (2) To assess the environmental similarity between the sampling and the unvisited sites, (3) To estimate the SOC content at the unvisited sites, according to the environmental similarity. A field test was carried out to verify the feasibility of the improved model. Taking Yunnan Province as the case study area, a total of 64 soil samples were derived from the World Soil Information Service (WoSIS) database. Three scenarios were then set using the total samples: (1) In the first scenario, 10 soil samples were randomly selected from the 64 soil samples as the training set, and the remaining 54 samples were used as test set. This selection was repeated for 20 times. As such, 20 groups were obtained for 10 training and 54 test samples. (2) In the second scenario, 20 samples were randomly chosen from the total samples as the training set, and the remaining 44 samples were employed as the test set. 20 groups were obtained as 20 training and 44 test samples. (3) In the third scenario, 30 samples were randomly derived from the total samples as the training set, and the remaining 34 samples were used as the test set. 20 groups were obtained as 30 training and 34 test samples. Two indices, namely mean absolute error (MAE) and root mean square error (RMSE), were used to measure the prediction accuracy of the three models. Analysis of variance (ANOVA) was applied to compare the prediction accuracy among the three models. The results showed that the MAE of ESM were 12.7, 11.7, and 11.1 g/kg, respectively, for the first, the second and the third scenarios, which were all significantly lower (P < 0.05) than those of MLR (72.6 g/kg, sample size n = 10; 23.0 g/kg, n = 20; 16.7 g/kg, n = 30) and ANN (15.8g /kg, n = 10; 14.9 g/kg, n = 20; 15.8 g/kg, n = 30). Therefore, the ESM was achieved in the high accuracy of prediction and strong robustness. The finding can provide a new way to predict the spatial distribution of SOC. [ABSTRACT FROM AUTHOR]

Trait heritability and the response to selection depend on genetic variation, a prerequisite to developing sorghum varieties with desirable agronomic traits and high carbon sequestration for sustainable crop production and soil health. The present study aimed to assess the extent of genetic variability and associations among agronomic and carbon storage traits in selected sorghum genotypes to identify the best candidates for production or breeding. Fifty genotypes were evaluated at Ukulinga, Bethlehem and Silverton sites in South Africa during the 2022/23 growing season. The following agronomic and carbon storage traits were collected: days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), grain yield (GY), harvest index (HI), shoot carbon content (SCc), root carbon content (RCc), grain carbon content (GCc), total plant carbon stock (PCs), shoot carbon stock (SCs), root carbon stock (RCs), and root-to-shoot carbon stock ratio (RCs/SCs), and grain carbon stock (GCs). Higher genotypic coefficient of variations (GCVs) were recorded for GY at 45.92%, RB (39.24%), RCs/SCs (38.45), and RCs (34.62). Higher phenotypic coefficient of variations (PCVs) were recorded for PH (68.91%), followed by GY (51.8%), RB (50.51%), RS (41.96%), RCs/SCs (44.90%), and GCs (41.90%). High broad-sense heritability and genetic advance were recorded for HI (83.76 and 24.53%), GY (78.59 and 9.98%), PB (74.14 and 13.18%) and PCs (53.63 and 37.57%), respectively, suggesting a marked genetic contribution to the traits. Grain yield exhibited positive association with HI (r = 0.76; r = 0.79), DTH (r = 0.13; r = 0.31), PH (r = 0.1; r = 0.27), PB (r = 0.01; r = 0.02), RB (r = 0.05; r = 0.06) based on genotypic and phenotypic correlations, respectively. Further, the path analysis revealed significant positive direct effects of SB (0.607) and RB (0.456) on GY. The RS exerted a positive and significant indirect effect (0.229) on grain yield through SB. The study revealed that PB, SB, RB, RS, RCs, and RCs/SCs are the principal traits when selecting sorghum genotypes with high yield and carbon storage capacity. [ABSTRACT FROM AUTHOR]

Coastal wetlands are seen as efficient coastal stabilizers and provide an optimal natural ecosystem for the sequestration and storage of carbon. Thus, it is critically important for scientists and environmental managers to understand the future dynamics of coastal wetlands. The understanding of yearly to decadal development in coastal ecosystems can assist in the coastal management activity, to sustain biodiversity. In the current study, high-resolution granulometric analysis of a back-barrier salt-marsh deposit of tropical barrier estuary environments at Chandipur, India, is utilized to provide an overview of the mesoscale geomorphic processes and history of changing sediment dynamics. The multivariate statistical examination with coefficients of probability density functions and compositional data analysis helps to determine the four lithofacies of the deposit. Granulometric analysis combined with satellite image analysis reveals that relatively coarser facies were deposited during the incipient stage of the barrier development, when the marshland vegetation was relatively less dense as suggested by the lower normalized difference vegetation index (NDVI) and the saline sea water easily drowned the area and saline sediment was deposited. After rapid marsh accretion, the flow dynamics shifted to a negligible flow component in the final stage when finer facies were deposited in vegetated marshland, and the organic carbon concentration increased up to 3.5%. As plant organic matter and sediment continuously accumulates in this marshland, elevation capital grows and the marsh continues to develop and expand, reaching a densely vegetated marsh with a considerable increase in NDVI values. The findings of this multiproxy study, in conjunction with multivariate statistical analysis, provide valuable insight into the characteristics of accretion in a tropical saltmarsh, which is unique in such a geological setting. [ABSTRACT FROM AUTHOR]

Wheat is a vital global food crop, yet it faces challenges in saline–alkali soils where Fusarium crown rot significantly impacts growth. Variations in wheat growth across regions are often attributed to uneven terrain. To explore these disparities, we examined well-growing and poorly growing wheat samples and their rhizosphere soils. Measurements included wheat height, root length, fresh weight, and Fusarium crown rot severity. Well-growing wheat exhibited greater height, root length, and fresh weight, with a lower Fusarium crown rot disease index compared to poorly growing wheat. Analysis of rhizosphere soil revealed higher alkalinity; lower nutrient levels; and elevated Na, K, and Ca levels in poorly growing wheat compared to well-growing wheat. High-throughput sequencing identified a higher proportion of unique operational taxonomic units (OTUs) in poorly growing wheat, suggesting selection for distinct fungal species under stress. FUNGuild analysis indicated a higher prevalence of pathogenic microbial communities in poorly growing wheat rhizosphere soil. This study underscores how uneven terrains in saline–alkali soils affect pH, nutrient dynamics, mineral content, wheat health, and rhizosphere fungal community structure. [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 35-day study investigated the impact of carbon sources and carbon/nitrogen (C/N) ratios on the microbial community of biofloc. For this purpose, we utilized a combination of phospho-lipid fatty acids (PLFAs) profiles and DNA-based sequencing methods to investigate changes in the microbial community composition and structure. The experiment involved three carbon sources including Dextrin (DEX), corn starch (CS) and wheat bran (WB) at two C/N ratios (19 and 30). The results indicated that WB and CS were found to decrease nitrogen metabolite concentration while increasing total suspended solids and bacterial density compared to DEX. The treatments exhibited variations in microbial communities and the use of polymerase chain reaction/ denaturing gradient gel electrophoresis analysis revealed distinct dominant bacterial species linked to carbon sources and C/N ratios. Furthermore, the highest levels of bacteria and protozoa PLFAs biomarkers were observed in the C/N30 ratio and WB treatment while the ratio for poly-β-hydroxybutyrate/PLFAs and fungi biomarkers displayed a decrease. Also, by incorporating the results of PLFAs profile and conducting a principal component analysis, the treatments were categorized into distinct groups based on both the carbon source and C/N ratios. Overall, both methods yield consistent results. PLFAs offered additional insights into the microbial composition beyond bacterial structure while DNA-based analysis provided finer taxonomic resolution. [ABSTRACT FROM AUTHOR]