Oil Fractions Research Articles

Organic Phosphorus Fractions in Relation to Soil Aggregate Fractions of Black Soil

Knowledge of long-term phosphorus behavior is essential to improve soil structure, nutrient supply potential, and the sustainability of cropping systems. A 45-year long-term experimental trial was used to observe organic phosphorus fractionation and its effects on soil aggregation and nutrient distribution at three depths (0–20, 20–40, and 40–60 cm) in Vojvodina Province, Serbia, under maize monoculture and maize/barley rotation. Five fertilizing systems were studied, including Control, NPK, NPK + maize remains, NPK + manure, and NPK + manure in rotation. Soil aggregates were fractionated into four size categories (>2000, 2000–250, 250–53, and <53 μm) using a wet sieving method. The samples were analyzed for main indicators, including different forms of phosphorus, total and available (PT and PA), as well as its organic forms (Labile Po, Biomass Po, Mod. Labile Po, Fulvic acid Po, Humic acid Po, and Resistant Po), and other fertility parameters. Significant differences in total and available phosphorus as well as all observed organic phosphorus fractions were evident between treatments with and without organic amendments, particularly in the 0–20 and 20–40 cm soil layers. Moderately labile P forms were dominant across all treatments, while labile forms constituted a smaller proportion. The most notable differences between treatments were observed in the labile and moderately labile forms, as well as in the resistant form of organic phosphorus. Manure application led to increased nutrient content in macroaggregates (>250 μm) compared to microaggregates. Microaggregates (<250 μm) were predominant across all depths, while stable structural aggregates did not show a significant increase after manure application. PCA highlighted significant correlations between soil characteristics, including total and available P, total organic carbon, clay content, and enzyme activity, across different aggregate sizes and organic P fractions. Overall, long-term mineral fertilization combined with organic amendment application induced variations in phosphorus fractions and the content of carbon, nitrogen, and phosphorus associated with aggregates in the first two soil layers, except for aggregate size classes.

Unlocking the potential of spent coffee grounds via a comprehensive biorefinery approach: production of microbial oil and carotenoids under fed-batch fermentation.

The valorization of renewable feedstock to produce a plethora of value-added products could promote the transition towards a circular bioeconomy. This study presents the development of cascade processes to bioconvert spent coffee grounds (SCGs) into microbial oil and carotenoids employing sustainable practices. The stepwise recovery of crude phenolic extract and coffee oil was carried out using green or recyclable solvents, i.e., aqueous ethanol and hexane. Palmitic acid (43.3%) and linoleic acid (38.9%) were the major fatty acids in the oil fraction of SCGs. The LC-MS analysis of crude phenolic extracts revealed that chlorogenic acid dominated (45.7%), while neochlorogenic acid was also detected in substantial amounts (24.0%). SCGs free of coffee oil and phenolic compounds were subjected to microwave-assisted pretreatment under different irradiations and solvents to enhance subsequent enzymatic saccharification. Microwave/water pretreatment at 400 W, followed by enzymatic hydrolysis with proteases, hemicellulases, and cellulases, at 50g/L initial SCGs, led to satisfying overall yields of cellulose (75.4%), hemicellulose (50.3%), and holocellulose (55.3%). Mannan was the most extractable polysaccharide followed by galactan and arabinan. SCGs hydrolysate was used in fed-batch bioreactor fermentations with Rhodosporidium toruloides to produce 24.0g/L microbial oil and carotenoids of 432.9μg/g biomass.

Efficient Removal of Water Soluble Fraction of Diesel Oil by Biochar Sorption Supported by Microbiological Degradation

The contamination of the water bodies by diesel oil (DO) and its water-soluble fraction (WSF) represents one of the most challenging tasks in the management of polluted water streams. This paper contains data related to the synthesis and characteristics of the plum stone biochar material (PmS-B), which was made from waste plum stones (PmS), along with its possible application in the sorption of the WSF of DO from contaminated water. Techniques applied in sample characterisation and comparisons were: Elemental Organic Analysis (EOA), Scanning Electron Microscopy−Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), pH (pHsus) and point of zero charge (pHpzc). In order to increase the overall efficiency of the removal process, sorption and bioremediation were subsequently combined. Firstly, PmS-B was used as a sorbent of WSF, and then the remaining solution was additionally treated with a specific consortium of microorganisms. After the first treatment phase, the initial concentration of diesel WSF was reduced by more than 90%, where most of the aromatic components of DO were removed by sorption. The sorption equilibrium results were best fitted by the Sips isotherm model, where the maximum sorption capacity was found to be 40.72 mg/g. The rest of the hydrocarbon components that remained in the solution were further subjected to the biodegradation process by a consortium of microorganisms. Microbial degradation lasted 19 days and reduced the total diesel WSF concentration to 0.46 mg/L. In order to confirm the non-toxicity of the water sample after this two-stage treatment, eco-toxicity tests based on a microbial biosensor (Aliivibrio fischeri) were applied, confirming the high efficiency of the proposed method.

[Intensive Citrus Cultivation Suppresses Soil Phosphorus Cycling Microbial Activity].

Soil microbes are key drivers in regulating the phosphorus cycle. Elucidating the microbial mineralization process of soil phosphorus-solubilizing bacteria is of great significance for improving nutrient uptake and yield of crops. This study investigated the mechanism by which citrus cultivation affects the soil microbial acquisition strategy for phosphorus by measuring the abundance of the phoD gene, microbial community diversity and structure, and soil phosphorus fractions in the soils of citrus orchards and adjacent natural forests. The results showed that citrus cultivation could lead to a decrease in soil pH and an accumulation of available phosphorus in the soil, with a content as high as 112 mg·kg-1, which was significantly higher than that of natural forests (3.7 mg·kg-1). Citrus cultivation also affected the soil phosphorus fractions, with citrus soil having higher levels of soluble phosphorus (CaCl2-P), citrate-extractable phosphorus (Citrate-P), and mineral-bound phosphorus (HCl-P). The phosphorus fractions of natural forest soils were significantly lower than those of citrus soils, whereas the phoD gene abundance and alkaline phosphatase activity were significantly higher in natural forest soils than in citrus soils. High-throughput sequencing results showed that the Shannon diversity index of phosphate-solubilizing bacteria in citrus soils was 4.61, which was significantly lower than that of natural forests (5.35). The microbial community structure in natural forests was also different from that of citrus soils. In addition, the microbial community composition of phosphate-solubilizing bacteria in citrus soils was also different from that of natural forests, with the relative abundance of Proteobacteria being lower in natural forest soils than in citrus soils. Therefore, citrus cultivation led to a shift of soil microbial acquisition strategy for phosphorus, with external phosphorus addition being the main strategy in citrus soils, whereas microbial mineralization of organic phosphorus was the main strategy in natural forest soils to meet their growth requirements.

Observationally constrained regional variations of shortwave absorption by iron oxides emphasize the cooling effect of dust

Abstract. The composition of soil dust aerosols derives from the mineral abundances in the parent soils that vary across dust source regions. Nonetheless, Earth system models (ESMs) have traditionally represented mineral dust as a globally homogeneous species. The growing interest in modeling dust mineralogy, facilitated by the recognized sensitivity of the dust climate impacts to composition, has motivated state-of-the-art ESMs to incorporate the mineral speciation of dust along with its effect upon the dust direct radiative effect (DRE). In this work, we enable the NASA Goddard Institute for Space Studies ModelE2.1 to calculate the shortwave (SW) DRE accounting for the regionally varying soil mineralogy. Mineral–radiation interaction at solar wavelengths is calculated according to two alternative coupling schemes: (1) external mixing of three mineral components that are optically distinguished, one of which contains embedded iron oxides; (2) a single internal mixture of all dust minerals with a dynamic fraction of iron oxides that varies regionally and temporally. We link dust absorption to the fractional mass of iron oxides based on recent chamber measurements using natural dust aerosol samples. We show that coupled mineralogy overall enhances the scattering by dust, and thus the global cooling, compared to our control run with globally uniform composition. According to the external mixing scheme, the SW DRE at the top of atmosphere (TOA) changes from −0.25 to -0.30Wm-2, corresponding to a change in the net DRE, including the longwave effect, from −0.08 to -0.12Wm-2. The cooling increase is accentuated when the internal mixing scheme is configured: the SW DRE at the TOA becomes -0.34Wm-2 with a net DRE of -0.15Wm-2. The varying composition modifies the regional distribution of single scattering albedo (SSA), whose variations in specific regions can be remarkable (above 0.03) and significantly modify the regional SW DRE. Evaluation against the AErosol RObotic NETwork (AERONET) shows that explicit representation of soil mineralogy and its regional variations reduces the low bias of model dust SSA while improving the range of variability across stations and calendar months. Despite these improvements, the moderate spatiotemporal correlation with AERONET reveals remaining modeling challenges and the need for more accurate measurements of mineral fractions in soils.

Effects of cover crops and nitrogen fertilization on soil physical properties, carbon and nitrogen fractions, and winter wheat yield in the Chinese loess plateau: A 4-year field experiment

Context or problemLone-term application of chemical fertilizers in farmland ensure adequate or profitable crop yields but may damage soil structure. Cover crops (CCs) have great potentials to improve soil quality and promote sustainable crop production. However, the combined impacts of CCs with nitrogen fertilization on soil quality and crop yields are not clear. Objective or research questionWe aimed to examine the effects of CCs combined with N fertilization rates on soil physical properties, C and N fractions in both bulk soils and aggregates, and crop yields, and to find the best management practice that improve both soil quality and crop yields synthetically. MethodsA 4-year summer CCs - winter wheat field experiment was conducted in the Loess Plateau of China. CCs with different species and combinations (CC) were soybean (SB), sudan grass (SG), a mixture of both (SS), and no cover crop (CK) and N fertilizer (NR) were applied to winter wheat at rates of 0 (N0), 60 (N60), and 120 (N120) kg N ha−1. Soil physical properties and C and N fractions in both bulk soils and aggregates were evaluated at 0–10, 10–20, and 20–40 cm soil depths. ResultsSoil total porosity (TP), saturated water content (SWC), capillary water capacity (CWC), and C and N fractions decreased while bulk density (BD) increased with the increase of soil depth. The CC, NR, and their interaction (CC×NR) had significant effects on soil BD, aggregate size distribution and stability (MWD), and C and N fractions and only CC and CC×NR had significant effects on other physical properties. The incorporation of CCs significantly increased the proportions of > 5 mm aggregates and C and N fractions in both bulk soils and aggregates, especially in 0–10 and 10–20 cm. And SB and SS improved soil other physical properties more than SG, especially in 0–10 cm, which decreased BD by 13.2% and 12.6% while increased TP by 6.5% and 8.3%, SWC by 14.3% and 15.3%, CWC by 13.9% and 14.2%, MWD by 16.6% and 14.4%, respectively, compared to CK. Additionally, soil physical properties improved more with N60 while the C and N fractions in both bulk soils and aggregates increased more with N120. However, BD increased by 2.6% and 3.3% in N60 and N120 than N0, respectively. The correlations between the proportion of macro-aggregates and soil C and N fractions at 0–10 and 10–20 cm indicated the positive effects of CCs on improving soil structure and fertility simultaneously. Aggregated-associated C and N fractions decreased firstly and then increased with the reduced aggregate sizes, and were higher in micro-aggregates than in other size classes. N60-SB increased wheat yields by 98.7% compared with N0-CK. ConclusionsOverall, the incorporation of soybean residue was the best management practice for winter wheat yield and soil fertility under the reduced N fertilization. Implications or significanceThe selection of CCs species should depend on farmland managements, and the appropriate CCs with N fertilizer rates would target the improvements in soil quality, the sequestration of soil organic carbon, and crop yields synergistically.

Chitosan-highland barley gliadin complex stabilizes Pickering emulsion

This study aimed to investigate the phase behavior of chitosan (Cs) - highland barley gliadin (HBG) complex and application in stabilizing Pickering emulsion. The turbidity results indicated that the insoluble complex was more likely to form between Cs and HBG at the higher concentration of HBG and NaCl (the optimal concentration ratio (1:40). The results of scanning electron microscope (SEM) and surface tension showed that the insoluble complex formed between Cs and HBG at pH 4.0 had better solubility and surface wettability. The results of isothermal titration calorimetry (ITC) indicated that each molecule of Cs could interact with 1, 2, and 7 HBG molecules under pH 2.5, 3.2, and 4.0, respectively. In addition, the Pickering emulsion stabilized by Cs-HBG complex showed great rheological properties, thermal stability and storage stability under the conditions of pH 4.0, concentration ratio (Cs:HBG) of 1:40, and oil fraction of 50%. These researches would contribute to the better utilization of polysaccharide-hydrophobic protein complex in the food and pharmaceutical fields.

Does microbial carbon use efficiency differ between particulate and mineral‐associated organic matter?

Abstract Microbial carbon use efficiency (CUE), a key parameter to characterize microbial carbon conversion efficiency, is assumed to be similar in soil models for different soil functional pools with varied organic matter composition and nutrient availability, that is, particulate organic matter (POM) and mineral‐associated organic matter (MAOM). However, empirical studies comparing microbial CUE in POM versus MAOM are largely lacking. It is not known whether microbial CUE variance may underpin the variant behaviour (i.e. turnover and composition) of different soil functional pools. Here we collected surface soils from 25 natural forests and grasslands with divergent edaphic properties, and compared microbial CUE in their POM versus MAOM using soil fractionation in combination with incubation using 18O‐labelled water. We also quantified edaphic properties, organic matter composition, microbial community structures and the stoichiometric imbalance of nitrogen (N) and phosphorus (P) relative to carbon based on the dissolved pool relative to microbial biomass (ImN and ImP) to investigate variables regulating microbial CUE and its variation in POM relative to MAOM (CUEPOM/CUEMAOM). In contrast to our expectation, microbial CUE did not consistently differ between POM and MAOM across sites, albeit with large inter‐sample variations in CUEPOM/CUEMAOM (from 0.3 to 4.4). Although MAOM had higher substrate quality, indicated by lower ratios of soil organic carbon to total nitrogen (C/NOM) and higher N‐compounds/aromatic ratios, and higher proportions of r‐strategists and fast‐growing bacteria in the microbial community than POM, POM and MAOM had similar degrees of N limitation (i.e. ImN), which was the best predictor of microbial CUE across all samples. Therefore, although MAOM harboured more N‐containing compounds than POM, N limitation was not necessarily lower, leading to an overall similar microbial CUE in POM and MAOM. Nevertheless, CUEPOM/CUEMAOM decreased with increasing P limitation in POM relative to MAOM. Overall, our paper presents a comprehensive, empirical study comparing microbial CUE in POM and MAOM of diverse soils, and our results support the use of similar microbial CUE for POM and MAOM in soil models, but also highlight potential contrasts in microbial CUE between soil pools under strong P limitation. Such inferences deserve attention under potentially increasing P limitation induced by N deposition. This study advances our mechanistic understanding of ecological patterns and processes from the organismic to the ecosystem scale based on soil microbial physiology and different soil functional pools. Read the free Plain Language Summary for this article on the Journal blog.

Oil-Air Distribution Prediction Inside Ball Bearing with Under-Race Lubrication Based on Numerical Simulation

Oil/air two-phase flow distribution in the bearings is the basis for bearing lubrication status identification and precise thermal analysis of the bearing. In order to understand the fluid behavior inside the under-race lubrication ball bearing and obtain an accurate oil volume fraction prediction model. A numerical study of ball bearing with under-race lubrication is carried out to study oil-gas two-phase distribution inside the bearing, and the influence of several parameters is quantified, like bearing rotating speed, oil flow rate, oil viscosity, and oil density. The results indicate that the oil fraction in the bearing cavity between the inner and outer ring shows a periodic distribution along the circumference direction, and the period is the same as the number of under-race oil supply holes. Oil distribution alone radial direction is affected by the outer-ring-guiding cage and centrifugal force, leading to oil accumulation near the outer ring. Different bearing running conditions and oil characteristics do not change the oil distribution trend alone in circumference and radial direction, but the difference ratio. Finally, based on the numerical simulation results, a formula for the average oil volume fraction prediction in the bearing ring cavity is constructed.

Proximal sensors for modeling clay mineralogy and characterization of soil textural fractions developed from contrasting parent materials

Proximal sensors combined with X-ray diffraction (XRD) have optimized soil characterization, but scarce studies have focused on predicting the contents of minerals under this scope. The objectives herein were to: a) use the portable X-ray fluorescence (pXRF) spectrometry, diffuse reflectance spectroscopy in the range of visible and near-infrared (Vis-NIR), magnetic susceptibility (χ) and XRD to characterize the mineralogy of soils derived from representative Brazilian soil parent materials, and b) create models to quantify the minerals obtained via XRD. Twenty-two soil profiles developed from gabbro, gneiss, quartzite, mineral and organic sediments were described with 53 soil horizons sampled. Each sample had the sand, silt and clay fractions separated and analyzed with XRD, pXRF, χ, and Vis-NIR. Models were created using the Random Forest algorithm permuting the following predictor variables (separately and combined): pXRF, parent material (PM), χ, soil texture (sand, silt, and clay content), and Vis-NIR. Models’ accuracy was calculated using the leave-one-out cross-validation method. Si, Al, Fe, Ca, K, and Ti contents obtained by pXRF and the χ discriminated the soil particle size fractions according to the parent material. XRD analysis allowed the evaluation of the pedogenetic development of soils and their relation to the respective parent material. The best models for mineral contents were found for hematite (Hm) (104)+(Gt) (130) (R2 = 0.85), Hm (110) + Mh (131) (R2 = 0.76), kaolinite (Kt) (001) (R2 = 0.73), Kt (002) (R2 = 0.80), mica (Mc) (001) (R2 = 0.77), and Mc (020) + Kt (020) (R2 = 0.81). Clay mineralogy content was accurately modeled using only pXRF and parent material data. This approach can facilitate and speed up detailed soil mineralogy characterization. Further studies are encouraged to model the content of minerals found in the sand and silt fractions of soils with diverse mineralogy via proximal sensors and using larger data sets.

Prediction of catalytic cracking performance during co-processing of vacuum gas oil and low-margin oil refining streams

Relevance. Expansion of catalytic cracking feedstock resources both due to the need to intensify the process to increase the yield of target products (high-octane gasoline, light olefins) and to deepen oil refining through the utilization of low-margin streams at refineries. Along with this, there is an urgent need to develop domestic mathematical tools for optimizing the catalytic cracking, predicting the process performance when the modes and feedstock qualities changes, as well as planning of production. This requires in-depth analysis and detailed study of the composition of oil fractions involved in processing and thermodynamics and kinetics of a heterogeneous process. The development and application of a mathematical model of the catalytic cracking, taking into account the composition and properties of the components involved in processing, makes it possible to quantitatively assess the yield and quality of target and by-products depending on the composition, physicochemical properties of the mixed feedstock, and the parameters of the technological regime, with an assessment of the possibility of their processing at an existing industrial facility. Aim. Experimental study of the composition and properties of mixed feedstock of catalytic cracking based on vacuum gas oil containing 5 to 20 wt % of extract of selective cleaning of oils, distillate, residual slack wax, and deasphalted oil, and prediction of the catalytic cracking indicators during their co-processing using a mathematical model. Methods. Liquid chromatography method to study the composition of feedstock materials of the catalytic cracking in combination with a number of standard methods for determining physico-chemical properties. Results. Using a set of experimental studies, the authors have established the patterns of changes in the composition and physico-chemical properties of the components and mixed feedstock of catalytic cracking containing 5–20 wt % of distillate and residual slack wax, deasphalted oil, and extract. The results obtained were used in development of a mathematical model of the heterogeneous catalytic cracking of feedstock, which takes into account the composition of oil fractions involved in processing and the patterns of catalyst deactivation by coke. Using a mathematical model, the authors established the patterns of changes in the composition and yield of process products when 5–20 wt % were involved in processing distillate slack wax and extracts of selective cleaning of oils mixed with vacuum distillate. Practical recommendations were developed on the possibility of expanding the hydrocarbon feedstock of the catalytic cracking, taking into account the fuel or petrochemical regime.

ПОДХОДЫ И МЕТОДЫ РАСЧЕТА ПРОСТОЙ РЕКТИФИКАЦИОННОЙ КОЛОННЫ ДЛЯ РАЗДЕЛЕНИЯ НЕФТИ

. The main methods and approaches to calculations of multicomponent rectification are considered. The peculiarity of the calculation of the processes of separation of oil and oil fractions is shown

РАЦИОНАЛЬНОЕ ИСПОЛЬЗОВАНИЕ ОТГОН-БЕНЗИНА, ПОЛУЧЕННОГО ПРИ РЕКТИФИКАЦИИ ГИДРОГЕНИЗАТА ГЛУБОКОГО ГИДРИРОВАНИЯ СМЕСИ УТЯЖЕЛЕННЫХ СРЕДНЕДИСТИЛЛЯТНЫХ ФРАКЦИЙ ВТОРИЧНОЙ ПЕРЕРАБОТКИ НЕФТИ

This paper discusses ways to rationally use a side stream (distillate gasoline) from a rectification unit for alkalized hydrogenation product of deep hydrogenation of a mixture of heavy middle distillate frac-tions of secondary oil refining. It has been shown that distillate gasoline is a mixture of hydrocarbons, predominantly naphthenic and isoparaffin, has a low sulfur content, and can be used to produce high-octane gasoline through the catalytic reforming process

Influence of Varying Oil-Water Contents on the Formation of Crude Oil Emulsion and Its Demulsification by a Lab-Grown Nonionic Demulsifier.

This study describes how varying oil/water contents affect emulsion formation and the impact they have on emulsion droplet size, viscosity, and interfacial behavior. Crude oil (continuous phase) volume fractions of 40, 50, 60, and 70 vol % were probed in the various W/O emulsions formed. Experimental results from optical morphology revealed the emulsion droplets kept reducing as the crude oil fraction kept increasing, while the droplets were nearly unnoticeable in the emulsions derived from 60 and 70% crude oil. The viscosity-shear rate of emulsions produced from 40, 50, and 60 vol % crude oil exhibited a non-Newtonian behavior owing to the substantial volume of water content in their emulsions, whereas the viscosity-shear rate of the emulsion with 70 vol % crude oil exhibited a Newtonian behavior similar to the pure crude oil, suggesting a thorough blending of oil-water at this crude oil fraction. Besides, the viscosity-temperature measurements revealed that the viscosity of these emulsions diminished as the temperature increased and the viscosity reduction became more noticeable in an emulsion comprising 70 vol % crude oil. In the interfacial assessment, the increased crude oil content in the produced emulsion led to a sharp reduction in the interfacial tension (IFT). The IFT values after 500 s contacts between the emulsion and water (surrounding phase) were 11.86, 10.02, 8.08, and 6.99 mN/m for 40, 50, 60, and 70 vol % crude oil, respectively. Demulsification experiments showed that water removal becomes more challenging with a large volume of crude oil and a small water content. Demulsification performances of the lab-grown nonionic demulsifier (NID) after 10 h of demulsification activity at room temperature (25 °C) were 98, 90, 17.5, and 10% for the emulsions formed from 40, 50, 60, and 70 vol % crude oil, respectively, indicating that the demulsification degree decreases with an increasing crude oil content. Viscosity-time determination was applied to affirm the activity of NID on the emulsion formulated with a 50% crude oil fraction. The injection of NID in this emulsion triggered a sharp viscosity reduction, indicating the adsorption of NID at the oil-water interface and disruption of emulsifiers, enabling emulsion stability.

Adaptive multi-paddock grazing increases mineral associated soil carbon in Northern grasslands

Grassland soils play an important role in sequestering carbon (C) and are primarily used for livestock grazing. Grazing management can increase the amount of C stored in soils and the distribution of C in different soil fractions by altering soil microbial community structure, thereby influencing the persistence of soil C over time. Adaptive multi-paddock grazing (AMP), grazing cattle at high stock densities with long periods between grazing events, is considered to enhance grassland sustainability, productivity, and soil C compared to more conventional grazing practices (continuous to slow rotational). However, whether and how AMP grazing might affect the amount of C stored in different soil fractions has received little attention. Soil samples (0–15 cm depth) were collected from 24 ranches in a paired design, where 12 ranches practiced AMP grazing and 12 neighboring ranches practiced conventional grazing. Soil organic C (SOC) and total nitrogen were measured in different soil particle size [fine (<53 µm), medium (53–250 µm) and coarse (>250 µm)], and density [light (>1.6 g cm−3), and heavy (<1.6 g cm−3)] fractions. Soil bacterial and fungal biomass and abundances were obtained from phospholipid fatty acid analysis. Mean weights of soil microaggregates and heavy fractions were higher in soil exposed to AMP grazing, whereas mean weights of macroaggregates and light fractions were higher in conventionally grazed soils. In warmer and drier climatic conditions, SOC in both bulk soils and within various size and density fractions tended to decrease. Soil organic C (both concentration and stock) were significantly higher in the fine soil fractions under AMP management than conventionally grazed grasslands. Given that SOC in fine fractions, is more mineral associated and recalcitrant, our results indicate that AMP grazing increased the size of the stable SOC pool. The increased carbon pool in the fine fraction was associated with greater fungal to bacterial ratios, suggesting a possible biological mechanism for the increase. Overall, the results indicate that AMP grazing may be beneficial for sequestering more stable carbon that helps mitigate the effects of climate change.

Biochar-nanoparticle combinations enhance the biogeochemical recovery of a post-mining soil

Here we addressed the capacity of distinct amendments to reduce arsenic (As), copper (Cu), selenium (Se) and zinc (Zn) associated risks and improve the biogeochemical functions of post-mining soil. To this, we examined nanoparticles (NPs) and/or biochar effects, combined with phytostabilization using Lolium perenne L. Soil samples were taken in a former metal mine surroundings. Ryegrass seeds were sown in pots containing different combinations of NPs (zero-valent iron (nZVI) or hydroxyapatite (nH)) (0 and 2 %), and biochar (0, 3 and 5 %). Plants were grown for 45 days and the plant yield and element accumulation were evaluated, also soil properties (element distribution within the soil fractions, fertility, and enzymatic activities associated with microbiota functionality and nutrient cycling) were determined. Results showed biochar-treated soil had a higher pH, and much higher organic carbon (C) content than control soil and NP-treated soils, and it revealed increased labile C, total N, and available P concentrations. Soil treatment with NP-biochar combinations increased exchangeable non-acid cation concentrations and reduced exchangeable Na%, improved soil fertility, reduced sodicity risk, and increased ryegrass biomass. Enzymatic activities, particularly dehydrogenase and glucosidase, increased upon the addition of biochar, and this effect was fostered by NPs. Most treatments led to a significant reduction of metal(loid)s contents in biomass, mitigating contamination risks. The two different NPs had similar effects in many parameters, nH outperformed nZVI in terms of increased nutrients, C content, and enzymatic activities. On the basis of our results, combined biochar-NP amendments use, specially nH, emerges as a potential post-mining soil restoration strategy.

GEMAS: Phosphorus in European agricultural soil - sources versus sinks at the continental-scale - the geological perspective

Phosphorus (P) is one of the essential elements for life on Earth. As a major nutrient it is needed for healthy growth both in plants and living organisms. Although the abundance of P in the Earth's upper continental crust is relatively high (655 mg/kg), many soil types are poor in available phosphorus. The main natural factors controlling the availability of P in soil are pH, mineralogy, and formation of insoluble complexes with Al and Fe under acidic, and with Ca and Mg under alkaline soil conditions. Superimposed weathering processes and climate contribute strongly to P mobility and availability. Additionally, a large fraction of total soil P is in organic forms, which are not directly available to plants. Phosphorus is a major component in fertilisers and thus a significant source of anthropogenic P in soil and water.In the agricultural soil samples that were collected during the Geochemical Mapping of Agricultural and grazing land Soil (GEMAS) project, the total P concentrations (XRF, median 786 m/kg) are only slightly higher than those extracted by hot aqua regia (AR, median 653 mg/kg), while the median concentration in the weak MMI® cold extraction is as low as 4.1 mg/kg. The AR results show very low P concentrations over the coarse-grained sandy sediments of the last glaciation in central and northern Europe and in calcareous soil. The southern limit of the last glaciation is visible as a concentration break on the geochemical maps. In general, north-eastern and north-western Europe are marked by high P values, probably related to cold and humid climate and enrichment in humus-rich coastal soil. The spatial distribution of P at the continental-scale is dominated by geogenic and climatic factors, and the anthropogenic influence is difficult to assess and quantify.

Isolation and characterization of bioactive alkaloids and GC–MS based identification of volatile oil metabolites from fruits of Glycosmis pentaphylla and evaluation of their cytotoxic activity

Glycosmis pentaphylla, a member of the Rutaceae family, has been extensively studied for its pharmacological activities, focusing mainly on the cytotoxic properties of its roots and stems. Conversely, limited researched has been done in terms of the phytochemical composition of the fruits. The objective of this study is to isolate and identify the bioactive compounds found in the fruits of G. pentaphylla and then evaluate their potential for anti-cancer activity in oral cancer CAL 27 cell lines. The extraction of bioactive compounds from fruits was done by maceration, and the isolation of alkaloids and volatile oil fractions (F1-F5) was performed by column chromatography. The alkaloids, such as 3-O-methoxyglycocitrine II, noracronycine, 1-hydroxy-3-methoxy-10-methyl-9-acridone and kokusaginine, were first isolated from the fruits of G. pentaphylla. Additionally, GC–MS analysis identified 78 metabolites. The isolated compounds and identified volatile oil fractions were explored for their anti-cancer activity by cell viability assay. Results demonstrated that isolated compounds were found inactive, while the volatile fraction F1 was found active in CAL 27 cell line. Fraction F1 impeded wound healing in CAL 27 cells by scratch assay, and significantly inhibited colony formation in colony formation assay. In cell cycle analysis, treatment with fraction F1 redistributed cells to the S and G2 phases of the cell cycle. α-elemol (2) is the major metabolite identified from the F1 fraction by GC–MS, which could be responsible for the anti-cancer activity. There is potential for future work to further isolate volatile oil metabolites and evaluate their anti-cancer activity through in-vivo techniques.

The green tide causative-species Ulva prolifera responding to exposure to oil and dispersant

In order to study the role of oil spills in the occurrence of green tide in the Yellow Sea, the physiological characteristics and photosynthetic activities of green tide causative-species Ulva prolifera was monitored under different conditions including two oil water-accommodated fractions (WAFs) of diesel oil and crude oil, dispersed water-accommodated fractions (DWAFs) and dispersant GM-2. The results showed that, the physiological parameters of U. prolifera including the growth, pigment, carbohydrate and protein contents decreased with the increased diesel oil WAF (WAFDO) concentration, while crude oil WAF (WAFCO) showed low concentration induction and high concentration inhibition effect. In addition, with the increase of WAFs concentration, two antioxidant activities were activated. However, compared with WAFDO alone and WAFCO alone, the mixture of oil and dispersant enhanced the toxicity on the above physiological characteristics of U. prolifera. On the other hand, the photosynthetic efficiency of U. prolifera showed a similar trend. Two WAFs showed significant concentration effects on the chlorophyll-a fluorescence transients and JIP-test. The addition of dispersant further blocked the electron flow beyond QA and from plastoquinone (PQ) to PSI acceptor side, damaged the active OEC centers at the PSII donor side, suppressed the pool size and the reduction rate of PSI acceptor side, and reduced the energy transfer efficiency between PSII functional units. These results implied that the crude oil spills may induce the formation of U. prolifera green tide, and the oil dispersant GM-2 used after the oil spills is unlikely to further stimulate the scale of bloom, while the diesel oil spills is always not conducive to the outbreak of green tide of U. prolifera.

Land–atmosphere coupling exacerbates the moisture-associated heterogeneous impacts of compound extreme events on maize yield in China

Compound climate events are major threats to crop production under climate change. However, the heterogeneity in the impact of compound events on crop yield and its drivers remain poorly understood. Herein, we used empirical approach to evaluate the impact of compound hot–dry (HD) and cold–wet (CW) events on maize yield in China at the county level from 1990 to 2016, with a special focus on the spatial heterogeneity. Our findings indicate comparable impact of extremely compound CW events (−12.8 ± 3.6%) on maize yield loss to extremely compound HD events (−11.3 ± 2.1%). The spatial pattern of compound HD and CW events impacts on maize yield was dominantly associated with moisture regime, followed by management practices and soil properties. Specifically, drier counties and counties with less fraction of clay soil and organic carbon tend to experience greater yield loss due to compound HD events, and wet condition, excessive fertilizer, clay soil and rich organic carbon aggravate the maize yield loss due to compound CW events. Moreover, the land–atmosphere coupling exacerbated the heterogeneous yield impact through divergent heat transfer. In drier regions, the greater proportion of sensible heat creates a positive feedback between drier land and hotter atmosphere. In contrast, the greater proportion of latent heat in wetter regions results in a positive feedback between wetter land and colder atmosphere. Our results highlighted a critical element to explore in further studies focused on the land–atmosphere coupling in agricultural risk under climate change.