Soil Water Research Articles

Afforestation Reduces Deep Soil Carbon Sequestration in Semiarid Regions: Lessons From Variations of Soil Water and Carbon Along Afforestation Stages in China's Loess Plateau

AbstractAfforestation represents an effective approach for ecosystem restoration and carbon (C) sequestration. Nonetheless, it poses notable challenges concerning water depletion and soil drought in (semi)arid regions. The underlying mechanisms regulating the influence of afforestation on soil carbon‐water dynamics, particularly how deep soil C reacts to afforestation‐induced soil drying, remain largely unclear. This study examined the variations of soil water content (SWC), soil organic carbon (SOC), and soil inorganic carbon (SIC) in 500 cm depth along four afforestation stages: abandoned grasslands, shrublands, and 20‐year and 40‐year Robinia pseudoacacia forests (RP20 and RP40) in the semiarid Loess Plateau, China. The results indicated that afforestation has significantly increased SWC (+26.6%), SOC (+44.5%), and SIC (+6.5%) in the shallow layer (0–100 cm) but caused evident soil drying (−60.8%), decrease in SOC (−37.8%), and slight reduction in SIC (−0.3%) in the deep layer (300–500 cm) when compared with grasslands. The seriously decline in the coupling coordination between soil C and SWC in the middle and deep layers indicates the unsustainability of afforestation especially for RP40. Structural equation model showed that the negative impact of afforestation on deep SOC through soil water depletion (−0.38) outweighed the direct positive impact of increased aboveground biomass (AGB) (+0.33). The negative impacts of decreased SWC and increased pH on deep SIC was close to the positive impacts of AGB. Afforestation has different effects on SOC and SIC across shallow and deep layers, and its negative effects on deep soil C should be fully integrated into future forest ecosystem restoration and management efforts.

Multiscale Characterization of the Albian-Cenomanian Reservoir System Behavior: A Case Study from the North East Abu Gharadig Basin, North Western Desert, Egypt

Since its discovery in 2010, the NEAG 2 has been one of the most productive oil fields of the Badr El-Din Petroleum Company (BAPETCO) in the northern Western Desert of Egypt. The Albian-Cenomanian reservoir system has a unique performance but suffers from several issues hindering its production. The latest production report in 2023, NEAG-2 Field was producing 1760 bbls of oil with 36500 bbls of water, i.e., 95% water cut. Despite that, the field has reached a 39% recovery factor but the reservoir forecast suggests a much higher recovery factor. Therefore, the NEAG 2 Field requires a comprehensive geological model to depict its reservoir heterogeneities better. We introduce a solid and integrated workflow to investigate the reservoir characters among different scales of geological heterogeneity and offer solutions to overcome some data gaps. After characterizing the reservoir elements by the structural, stratigraphic, petrographic, and petrophysical analyses, a machine learning-based method was applied to overcome the missing whole rock cores in creating a detailed electro-facies log for all field wells. The Neural-Network algorithm required the facies types to be grouped into definitive reservoir qualities to be applied. The resultant electro-facies log had a very good match with the input logs, which validated the facies grouping. This was followed by the porosity-permeability transforms, estimated from mobility data, to create a permeability curve for all field wells, despite the unavailability of core data. The reservoir was categorized into three rock types, each with a specific range of quality, signifying their different flow abilities which were supported by dynamic data. The Lower Bahariya-Kharita in NEAG 2 was ultimately concluded to be a complex heterogeneous reservoir with varying flow abilities and production behaviors. The recovery factor mismatch is due to unrecovered reserves, and a new production strategy should be introduced to reach the ultimate recovery. This integration of geologic and dynamic data is strongly recommended for any reservoir characterization study to avoid oversimplifying the reservoir system and to design the right reservoir development plan.

Study of the rheology and flow risk of hydrate slurries containing combined anti-agglomerants: Effects of wax, water cut and continuous phase composition

Study of the rheology and flow risk of hydrate slurries containing combined anti-agglomerants: Effects of wax, water cut and continuous phase composition

A novel neutralization process for improving dehydration performance of industrial by-product gypsum

By-product gypsum, produced through the traditional neutralization precipitation method for treating industrial acidic wastewater, is difficult to recycle due to its high moisture content. In this study, we proposed a novel neutralization process i.e. the two-stage neutralization method. By-product gypsum was used as an alkaline neutralizer and recycled as seed crystals for the first time. The original by-product gypsum has the poor dehydration performance due to its small particle size and the presence of colloids on its surface. After adding the by-product gypsum to the acidic wastewater, the ratio of CaO/SO3 in the system descended and colloids were dissociated. On the one hand, the alkaline component of the incomplete reaction continues to play a neutralizing role. On the other hand, CaSO4·2H2O particles act as seed crystals, promoting rapid growth of new crystals along their surface, which effectively improved crystallization performance and dehydration performance of the neutralization slag (outward discharge of slag). Compared with the original method, the wet weight of the neutralization slag is decreased from 186.0 g/L to 88.8 g/L, and the water cut is declined from 64.5% to 34.1%. The utilization ratio of the carbide slag augmented from 63.0% to 99.47%.

Polydopamine-incorporated MOF membrane with hydrophilicity for effective oil/water separation and fouling-resistant model analysis and prediction

A large number of oil spills and oily wastewater are discharged, in the modern industrial production process, resulting in serious water pollution. Oily wastewater can be extremely harmful to ecosystems and human health. Oil-water separation has become a major challenge at present, and membrane separation has aroused more and more concern in recent years due to its high economic efficiency. This paper fabricated PES filtration membranes using the novel nanoparticlesbased on both metal–organic frameworks-5 (MOF-5) and polydopamine (PDA) layers as dopants, and then adequately explored the porosity, morphology, separation, hydrophilicity, and fouling-resistant performance of the resultant membranes. In addition, the prepared membranes were used for oil–water separation, including soybean-in-water, petroleum ether-in-water, and gasoline-in-water emulsions. MOF@PDA membranes exhibit high separation efficiency of up to 99.8%. Subsequently, membrane fouling mechanisms were investigated using the Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and the molecular mode of interaction with the three oil–water emulsions with the membrane was compared. Newly prepared MOF@PDA membranes have better stability, fouling-resistant, and self-cleaning properties. Finally, an optimal machine learning model for oil–water separation efficiency was developed with a high prediction accuracy of 98%. The obtained results indicate that mixed matrix membranes exhibit excellent oil–water separation performance, demonstrating great application prospects in the remediation of oily wastewater.

Bioinspired superhydrophobic polysulfone foams with micro/nano hierarchical structures for highly efficient solar-assisted cleanup of viscous crude oil

Three-dimensional (3D) superhydrophobic/superoleophilic foams are promising candidates for swiftly and continuously separating immiscible and emulsified oil–water mixtures, but still need further study to fully improve their comprehensive performance, especially for viscous oils. This work designed and prepared superhydrophobic core–shell polydopamine nanoparticles modified polysulfone foams (denoted as SPP foams) with hierarchical micro/nano-structures, which exhibited robust super-wetting property (θwater = 163.1°, θoil = 0°). Immiscible oil–water compounds and water-in-oil emulsions could be continuously separated by the SPP foams with separation efficiencies higher than 99 %. The SPP foams showed high absorption capacity towards different types of oils and organic solvents (between 20 and 30 times of self-weight). The SPP foams also exhibited excellent self-cleaning ability, resistance to strong acids and alkalis, and long-term reusability. Through the integration of polydopamine, the foams achieved prompt photothermal conversion (the surface temperature could be increased to 80.7 °C in 1 min under 1 sun), and the generated heat could noticeably decrease the viscosity of crude oil, realizing efficient recovery of vicious crude oil. This study made progress in superhydrophobic/superoleophilic absorbent fabrication and the obtained SPP foams had great potential in treating oil spills especially in the aspect of solar-assisted cleanup of viscous oils.

Stimulated Pickering emulsion stabilized by binary particles with contrasting wettability and trace surfactant

The investigationof self-assembled particle structures at fluid interfaces has gained considerable interest across various fields. In particular, Pickering emulsions (PEs) stabilized by binary particles co-assembling at these interfaces have attracted even more attention. To explore the self-assembly process of superhydrophobic and superhydrophilic particles at oil–water (O/W) interfaces influenced by a trace amount of surfactant, a series of experiments were conducted. A small quantity (0.01 mmol·L−1) of dodecyltrimethylammonium bromide (DTAB) was introduced, establishing a variable stable emulsion system with high salt tolerance, capable of withstanding up to 6 mol·L−1 NaCl, in synergism with the particles. The DTAB concentration required to stabilize the O/W emulsion with particles was as low as 0.001 mmol·L−1. The stability and type of the resulting emulsion could be adjusted by varying the ratio of hydrophobic to hydrophilic particle (R) or by modifying acid/base conditions. The systems exhibited robust cyclic acid/base regulated demulsification and phase inversion behavior, maintaining stability over at least 10 cycles. Results indicated that the stability and nature of the emulsion were influenced by the curvature of the interface formed by the self-assembled interfacial particle structures, arising from the competitive adsorption of both types of particles and trace surfactant. Further analysis revealed a correlation between interfacial curvature and the surface charges of the particles, which could be modulated through DTAB adsorption. This study elucidated the behavior of hydrophilic and hydrophobic particle self-assembly at interfaces, provided a straightforward strategy for co-preparing switchable emulsions using superhydrophilic and superhydrophobic particles, and expanded the range of amphiphilic particles available for producing PEs. This approach presents significant potential for future research and applications in the field of PEs.

Bioinspired multi-functional modified PVDF membrane for efficient oil-water separation

The pervasive issue of oily wastewater presents a critical environmental challenge, necessitating the development of advanced membranes that offer high purification efficiency, durability, and versatility. In this study, we introduce a novel bioinspired multifunctional membrane, synthesized by modifying polyvinylidene fluoride (PVDF) with fibrous two-dimensional carbides and nitrides (MXene) and silica (SiO2) nanoparticles, drawing inspiration from the complex structure of coral stones. The membrane was fabricated using the phase inversion technique, producing a robust material that achieves over 99% separation efficiency for oil–water mixtures. Beyond oil–water separation, the membrane exhibited exceptional performance in removing various contaminants from complex oily wastewater, including heavy metals, dyes, and phenol. Remarkably, the membrane maintained its high purification efficiency even after 5 consecutive cycles of oil–water separation and pollutant adsorption. This bioinspired multifunctional modified PVDF (MMP) membrane represents a major advancement in wastewater treatment technology, with significant potential for widespread application in the purification of complex oily wastewater.

Physico-chemical properties of borehole water and heavy metal contamination in soil near an open dumpsite in Giwo District, Bauchi, Nigeria.

Physico-chemical properties of borehole water and heavy metal contamination in soil near an open dumpsite in Giwo District, Bauchi, Nigeria.

Safety and efficacy of a feed additive consisting of an essential oil derived from the flowering stems of Salvia sclarea L. (clary sage oil) for use in all animal species (FEFANA asbl).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of an essential oil from the fresh or dried flowering stems of Salvia sclarea L. (clary sage oil) when used as a sensory additive in feed and in water for drinking for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive under assessment is considered safe up to the maximum use level in complete feed of 15 mg/kg for veal calves (milk replacers), cattle for fattening, sheep/goats, 10 mg/kg for horses, 20 mg/kg for dogs, salmonids and ornamental fish. For the other target species, the calculated safe concentrations were 5 mg/kg for chickens for fattening, 8 mg/kg for laying hens, 7 mg/kg for turkeys for fattening, 9 mg/kg for piglets, 11 mg/kg for pigs for fattening, 14 mg/kg for sows, 13 mg/kg for dairy cows, 8 mg/kg for rabbits and 4 mg/kg for cats. These conclusions were extrapolated to other physiologically related species. For any other species, the additive is safe at 4 mg/kg complete feed. The FEEDAP Panel considered that the use level in water of clary sage oil is safe provided that the total daily intake of the additive does not exceed the daily amount that is considered safe when consumed via feed. The use of clary sage oil in animal feed under the proposed conditions of use is safe for the consumer and the environment. Regarding user safety, the essential oil under assessment should be considered as an irritant to skin and eyes and as a dermal and respiratory sensitiser. Since the oil of the flowering stems of S. sclarea is recognised to flavour food and its function in feed would be essentially the same as that in food, no further demonstration of efficacy was considered necessary.

Sustainable management of rice by-products: Environmental challenges, industrial applications, and circular bio-economy innovations

The agricultural sector plays an essential role in both human and economic growth, offering sustenance, employment, income, raw materials, technological progress, and sustainability. The growing awareness of the necessity to enhance agricultural production is gaining attention, primarily driven by the imperative to adequately nourish the continuously expanding global population. Diverse agricultural practices are causing harmful environmental consequences, posing a significant risk to ecological stability through issues such as soil degradation, water pollution, habitat loss, and biodiversity decline. Timely and effective agricultural waste management has become essential for preventing adverse environmental and health impacts. Biomass from rice crop harvesting and processing has been found in abundance around the world. Because of the abundance of this biomass in nature, researchers are harnessing it for various objectives, including global energy requirements, while supporting environmental sustainability. Due to this rationale, within the frameworks of emerging sustainable and circular models, the prioritization of agricultural waste valorization has gained prominence as a pivotal strategy aimed at advancing sustainable management and circular economy. This review mainly emphasizes on the rice bio-waste, its environmental and health-related issues, policies to control stubble burning, reduce pollution in the air, and sustainable management of the bio-waste into wealth using different approaches worldwide. We also investigated the potential contribution of rice-by-products wastes to bioenergy production (bioethanol, biogas, and biofuel), enzymes, nanoparticles, construction materials, animal husbandry, bioplastics, and other value-added products. We recommend that proper management of rice by-products may produce innovative bio-ingredients and biodegradable materials, and enhance green growth and a circular bioeconomy.

Improving plant-based protein drinks: the potential of flavors for cross-modal enhancement of fat perception

Fat perception is a complex phenomenon that influences the sensory experience of beverages. In this study, we explored the role of olfaction and flavor to modulate the fat perception and physical-chemical characteristics of protein-based emulsions with different fat contents. The emulsions consisted of pea protein isolate, canola oil and tap water. Two milky-creamy flavors were used, each with different composition and volatile profile. Our results showed that all fat contents (0, 1.5 and 3.5%) could be differentiated by the panelists. The fat-related creamy, milky, fatty, thickness and mouthcoating attributes had higher scores at higher fat contents, which positively correlated with the lubrication factor. Interestingly, adding flavor or blocking olfaction did not change the discrimination capacity, but the addition of flavor did cause a cross-modal effect on the fat perception. With olfaction, both flavors increased the fat descriptive aroma and mouthfeel attributes. Without olfaction, the taste and mouthfeel attributes were uninfluenced. Moreover, the flavors did not influence the physical-chemical characteristics at these low concentrations. Congruency of the flavor with fat increases the fat perception of the emulsions. Overall, this study suggests that fat congruent flavor can be utilized to modulate the fat perception in protein-lipid drinks, such as plant-based milks.

Exploring Lithium Extraction Technologies in Oil and Gas Field-Produced Waters: From Waste to Valuable Resource

Exploring Lithium Extraction Technologies in Oil and Gas Field-Produced Waters: From Waste to Valuable Resource

Impacts of prescribed fire and mechanical shredding of aboveground vegetation for fire prevention on ecosystem properties, structure, functions and overall multi-functionality of a semi-arid pine forest

Ecosystem multi-functionality is a key concept when measured to protect forests from natural and anthropogenic disturbances, such as fire prevention techniques, must be adopted. Despite this importance, scarce studies have analysed the impacts of prescribed burning and aboveground vegetation management on ecosystem functions and overall multi-functionality. To fill this gap, this study has evaluated the changes in some ecosystem properties and structure (associated with soil characteristics and plant diversity, respectively), in important forest functions, and the overall ecosystem multi-functionality in a Mediterranean pine forest of Castilla La Mancha (Central Eastern Spain) under three site conditions: (i) undisturbed ecosystem; (ii) forest subjected to mechanical shredding of aboveground vegetation (hereafter “AVMS”); and (iii) forest treated as above and then with prescribed fire (“AVMS + PF”). The results of the study have shown that neither the PF nor AVMS have significantly modified the structure, properties and functions as well as the overall multi-functionality of the forest ecosystem. These slight impacts of the treatments are due to the low fire severity of the prescribed burning and the long time elapsed from the vegetation management. Among the studied ecosystem functions, organic matter decomposition (driven by the enzymatic activities and soil basal respiration), water cycle (influenced by soil water content and water infiltration), carbon stock (linked to soil organic matter) and biomass production decreased, when species richness and plant diversity increased. The study is useful to indicate the feasibility of forest management actions for fire prevention in delicate forest ecosystems of the Mediterranean environments.

Reseeding increased plant biomass production and soil fertility, but not plant species diversity in degraded grasslands in China

Reseeding is a primary measure to restore degraded grasslands. Numerous studies have conducted experiments to investigate how the properties of grassland ecosystems respond to reseeding in China. However, there is a lack of summary of the results of these studies. Here, we conducted a hierarchical random-effects meta-analysis on the effects of reseeding on plant, soil, and microbial properties. We collected 19 variables, including plant biomass, species diversity and richness, soil organic carbon content, soil total and available nutrients, soil water content, soil microbial biomass and diversity, and enzyme activity, from a dataset of 1363 paired observations (degraded vs. reseeded) from 75 publications. The results showed that reseeding increased aboveground and belowground plant biomass by 70.2% and 68.0% on average, respectively. Reseeding increased soil organic carbon, phosphorus, and potassium contents, but did not affect soil nitrogen levels. Reseeding increased soil microbial nitrogen under conditions of tillage and fertilization. Reseeding age was found to have a positive correlation with species richness, while planting type, fertilization, and tillage did not have a significant impact on the species richness and diversity. Under the treatments of fertilization, non-tillage, and mix-planting, the response ratio of aboveground biomass to reseeding was positively correlated with the response ratio of species diversity to reseeding. Our results concluded that current reseeding practices can significantly improve plant biomass production and soil fertility but have minor effects on plant species diversity. These findings indicate that the preservation of biodiversity should receive greater attention from both researchers and practitioners in grassland remediation in China.

Multifunctional effects of nitrification and urease inhibitors: decreasing soil herbicide residues and reducing nitrous oxide emissions simultaneously

Glyphosate pollution and greenhouse gas emissions are major problem in achieving sustainable soil management. It is necessary to develop effective strategies to simultaneously reduce herbicide residues and nitrous oxide (N2O) emissions in soil. This study aimed to: (1) quantitative analyze the effects of nitrogen (N) cycle inhibitors (nitrification inhibitors 3,4 dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD) and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT)) on glyphosate degradation and reduction of N2O under different soil moistures; (2) identify the functional microbes and genes associated with glyphosate degradation and N2O emissions; and (3) decipher the main mechanisms of N cycle inhibitors affecting glyphosate degradation at different soil water contents. Compared to the control, the application of DMPP, DCD and NBPT reduced glyphosate residues in soil by 33.0%, 60.3% and 35.7%, respectively, under 90% water holding capacity (WHC). The application of DCD stimulated Acidobacteria and the phnX gene to degrade soil glyphosate. Further, soil glyphosate residues were significantly and negatively related to soil N2O emissions at both 60% and 90% WHC. Compared to the control, NBPT application decreased cumulative N2O emissions by 91.4% at 90% WHC by decreasing soil nitrate N (NO3--N) and inhibiting amoC and narG genes at 90%. The application of N cycle inhibitors could be a potential strategy to simultaneously reduce glyphosate residues and soil N2O emissions. Our study could provide technical support to reduce the risks of herbicide exposure and reduce greenhouse gas emissions.

Evaluating soil water and nitrogen transport, nitrate leaching and soil nitrogen concentration uniformity under sprinkler irrigation and fertigation using numerical simulation

Evaluating soil water and nitrogen transport, nitrate leaching and soil nitrogen concentration uniformity under sprinkler irrigation and fertigation using numerical simulation

Drainage estimation across mountainous regions from large-scale soil moisture observations

Drainage is a crucial soil hydrological process that governs the partitioning of rainfall into runoff, groundwater recharge, soil water storage and evapotranspiration. Despite its significance, the drainage process is poorly understood due to the difficulty in direct measurements and insufficient understanding of its underlying physical mechanisms. To address these challenges, we present an innovative, physically-based, data-driven approach, SM2D (Soil Moisture to Drainage), to estimate drainage. SM2D was applied and examined using soil moisture data from a large-scale observation network over mountainous areas during 2014–2020. The soil moisture threshold governing drainage initiation proves to be significantly lower than the commonly employed field capacity metric in hydrological models. This threshold is influenced by factors such as mean soil moisture, bulk density, residual soil moisture, soil organic carbon, and parameters n and α of soil retention curve. Notably, field capacity has minimal impact on this threshold. Additionally, our analysis reveals that the drainage process is more influenced by the Soil Water Storage Increment (SWSI) than by mean soil moisture (MSM) that has traditionally been recognized as a key factor in drainage control. In comparison to commonly used exponential equations and those in models such as the Soil & Water Assessment Tool (SWAT), SM2D demonstrates superior performance in estimating drainage. The exponential equation derived from the SWSI outperforms those derived from other soil moisture metrics, including the commonly utilized MSM, challenging prevailing norms in drainage equations. SM2D holds the potential to generate extensive drainage datasets from satellite or large-scale soil moisture observations, advancing large-scale hydrological studies.

Modelling of the trade-off between the deep soil moisture and vegetation restoration in the hilly area of the Loess Plateau, China

Excessive depletion of soil moisture by artificial forests in the vegetation restoration areas of the Loess Plateau has attracted widespread attention. To assess potential risks of soil moisture deficit, we needed on-site vegetation and soil sampling data, as well as UAV images from the Chaigou Watershed for three-dimensional analysis, combining both sampling and raster data. Three-dimensional surfaces for assessment of trade-off were established innovatively by the local regression and interpolation methods. The results indicated that soil moisture benefits at 20–40 cm depth are lower than at 0–20 cm due to infiltration and surface disturbance. In some areas of the Chaigou Watershed, grass and shrub-grass vegetation are facing risks of soil moisture deficit based on trade-off values (RSMD) and multiparameter evaluations. Analysis of deep soil water content variability revealed the moisture decreases significantly with the deepening of the soil layer in some plots. R (Richness), H (Shannon’s Diversity), Margalef, COHESION, and CONTAG were applicable in interpolation and fitted with the local regression model (R2 > 0.6) corresponding to the trade-off, but SPLIT was proven to be inapplicable in this study area. The zero trade-off inflection points were 6 %–8 %, while the trend inflection points were 7.5 %–9 % for soil moisture and vegetation indices of vegetation and landscape in typical sampling sites of the Chaigou Watershed. Three-dimensional fitting model is more comprehensive and effective in assessing deep soil moisture conditions and grass plots on shady slopes generally had the best trade-off status in this region.

Effects of Cover Crop on Selected Abiotic and Biotic Soil Health Indicators

Current cropping systems, like cover cropping, aim to improve soil health and crop productivity, with the former a more sustainable route to the latter. This can be done by evaluating the influence of cover crops (CCs) on soil health indicators, both abiotic and biotic, as is the objective of this study. Several CCs (crimson clover [Trifolium incarnatum L.], oats [Avena sativa], hairy vetch [Vicia villosa Roth.], winter wheat [Triticum aestivum L.], winter peas [Lathyrus hirsutus L.], flax [Linum usitassimum L.], triticale [Triticale hexaploide Lart.], cereal rye [Secale cereale], and barley [Hordeum vulgare L.]) were used across two research sites, set up using a completely randomized design with two levels of CCs (CC vs no cover crop [NC]) and three replicates during 2023. Soil samples were collected at 0-10, 10-20, and 20-30 cm depths and analyzed for soil physico-chemical properties and microbial biomass and composition. Results showed significantly lower bulk density values, greater water content (at 0 kPa soil water matric potential), greater volume-specific heat capacity (at 0 and -33 kPa soil water matric potential), greater total nitrogen, and numerically greater soil organic carbon under CC compared with NC management. This led to numerically greater microbial biomass and community composition (e.g., arbuscular mycorrhizal fungi, gram-negative and gram-positive bacteria, eukaryotes, and fungi), and slightly lower microbial stress indicators (genotypic and chemical structure categorizations) under CC compared with NC management. However, the lack of significant differences between treatments suggests that three years is insufficient to detect improvements in measured soil health indicators. Further, the significant differences in measured soil health indicators between study sites suggests an influence of soil texture and order, and this warrants further investigations.