Search Results (20)

Diuron (DU) is a widely used phenylurea herbicide designed to inhibit weed growth, but its high toxicity and prolonged half-life contribute significantly to environmental contamination. The majority of electrochemical (EC) sensors typically rely on a single response signal for the detection of DU, rendering them highly susceptible to interference from variable background noise in complex environments, thereby reducing the selectivity and robustness. By integrating molecularly imprinted polymer (MIP) with a ratiometric strategy, the aforementioned issues could be solved. In this study, a novel signal on-off ratiometric MIP-EC sensor was developed based on the MXene/PEI-MWCNTs nanocomposite for the detection of DU. Positively charged PEI-MWCNTs was used as an interlayer spacer and embedded into negatively charged MXene by a simple electrostatic self-assembly method. This effectively prevented the agglomeration of MXene and enhanced its electrocatalytic performance. The MIP was synthesized via electropolymerization with DU serving as the template molecule and the selectivity was enhanced by leveraging the gate effect of MIP. Subsequently, a ratiometric MIP-EC sensor was designed by introducing [Fe(CN)₆]^3−/4− into the electrolyte solution as an internal reference. Additionally, the current ratio signal (I_DU/I_[Fe(CN)6]^3−/4−) and DU concentration exhibited a good linear relationship within the range of 0.1 to 100 µM, with a limit of detection (LOD) of 30 nM (S/N = 3). In comparison with conventional single-signal MIP-EC sensing, the developed ratiometric MIP-EC sensing demonstrates superior reproducibility and accuracy. At the same time, the proposed sensor was successfully applied to the quantitative analysis of DU residues in soil samples, yielding highly satisfactory results. Full article

This study evaluated the adsorption and desorption of imidacloprid (IMI), thiamethoxam (THM) and clothianidin (CLO) in an andisol (Freire soil) and an inceptisol (Chufquén soil) from southern Chile with different organic matter and clay contents. The soils had a slightly acidic pH and clay and clay-loam textures. The tests were carried out at 20 °C with CaCl₂ 0.01 M as the electrolyte. Kinetic experiments were performed and isotherms were fitted to the pseudo-second-order, Elovich, Weber–Morris, Freundlich and Langmuir models. The kinetics were best described by the pseudo-second-order model (R² > 0.99), indicating chemisorption; the rate was the highest for THM, although IMI and CLO achieved the highest retention capacities. The Chufquén samples, with lower organic matter but 52% clay, exhibited the highest K_f and q_m of up to 12.4 and 270 mg kg⁻¹, respectively, while the K_d (2.3–6.9 L kg⁻¹) and K_oc (24–167 L kg⁻¹) coefficients revealed a moderate leaching risk. THM was the most mobile compound due to its high solubility. Desorption was partially irreversible (H = 0.48–1.48), indicating persistence in soil. FTIR analysis confirmed the interaction with O-Al-O/O-O-Si-O groups without alterations in the mineral structure. In the soils examined in this study, the clay fraction and variable-charge minerals, rather than organic matter, were more closely associated with the adsorption behaviour of these NNIs. Full article

Compared to traditional biochar (BC), nano-biochar (NBC) boasts superior physicochemical properties, promising extensive applications in agriculture, ecological environments, and beyond. Due to its strong adsorption and migration properties, NBC may carry nutrients or pollutants to deeper soil layers or even groundwater, causing serious environmental risks. Nevertheless, the migration rules and mechanisms of NBC in soil are still unclear. Therefore, this study employed soil column migration experiments to systematically explore the migration rules and mechanisms of NBC under various flow rates, initial soil water contents, soil depths, and soil textures. The results showed that regulated by smaller particle size differences and greater surface charges, NBC exhibited a stronger migration ability compared with traditional BC. As the soil texture transitioned from fine to coarse, the migration capability of NBC significantly improved, driven by both pore structure and interaction forces as described by the DLVO theory. The migration ability of NBC was also greatly boosted as the soil transitioned from saturated to unsaturated conditions, primarily because of preferential flow. When the flow rate increased from 70% KS to 100% KS and 130% KS, the migration ability of NBC also increased accordingly, as changes in injection flow rates altered the velocity distribution of pore water. NBC in 25 cm soil columns was more prone to shallow retention compared with 10 cm soil columns, resulting in weaker overall migration ability. In addition, through fitting of the two-site kinetic model and related parameters, the penetration curves of NBC under various variable conditions were effectively characterized. These findings could offer valuable insights for NBC’s future efficient, rational, and sustainable utilization, facilitating the evaluation and mitigation of its potential environmental risks. Full article

Extrusion-based 3D Construction Printing (3DCP) involves developing novel material mixtures that incorporate local geo-materials. Given that clay minerals and silt are major causes of soil variability, this study focuses on the fine fraction of soil to facilitate purpose-oriented design, classification, and standardization. We begin with an overview of current research in the field and general information about clays. Subsequently, we establish an evaluation methodology, examining various clay–sand mix ratios, along with locally sourced material to gain general insights into the material’s clay-dependent macro-printability characteristics. The findings are then correlated and discussed in relation to the microcharacteristics of the clays, emphasizing the significance of both intraparticle and interparticle swelling for strength and cohesiveness. Factors such as swelling ability, and charge, which may be reflected by pH, are pivotal for strength; while the quantity of clay and its interparticle swelling ability, denoted by the plasticity index (PI), delineate cohesiveness, which is essential for pumpability and extrudability. Furthermore, the presence of organic material and other minerals is observed to have a significant impact on these properties. Full article

The role of modified biochar in enhancing phosphorus (P) availability is gaining attention as an environmentally friendly approach to address soil P deficiency, a global agricultural challenge. Traditional phosphatic fertilizers, while essential for crop yield, are costly and environmentally detrimental owing to P fixation and leaching. Modified biochar presents a promising alternative with improved properties such as increased porosity, surface area, and cation exchange capacity. This review delves into the variability of biochar properties based on source and production methods and how these can be optimized for effective P adsorption. By adjusting properties such as pH levels and functional groups to align with the phosphate’s zero point of charge, we enhance biochar’s ability to adsorb and retain P, thereby increasing its bioavailability to plants. The integration of nanotechnology and advanced characterization techniques aids in understanding the structural nuances of biochar and its interactions with phosphorus. This approach offers multiple benefits: it enables farmers to use phosphorus more efficiently, reducing the need for traditional fertilizers and thereby minimizing environmental impacts, such as greenhouse gas emissions and P leaching. This review also identifies existing research gaps and future opportunities for further biochar modifications. These findings emphasize the significant potential of modified biochar in sustainable agriculture. Full article

Natural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of cationic chitosan, charge-neutral guar gum, and anionic xanthan gum during compaction. The results of laboratory investigations indicate that the flow through and volume change properties of the expansive soil were affected variably. The dual porosity, characterized by low air entry due to inter-aggregate pores (AEV₁ of 4 kPa) and high air entry due to the clay matrix (AEV₂ of 200 kPa) of the soil, was healed using chitosan and guar gum (AEV of 200 kPa) but was enhanced by the xanthan gum (AEV₁ of 100 kPa and AEV₂ of 200 kPa). The s-shaped swell–shrink path of the soil comprised structural (e from 1.23 to 1.11), normal (e from 1.11 to 0.6), and residual stages (e ranged from 0.6–0.43). This shape was converted into a j-shaped path through amendment using chitosan and guar gum, showing no structural volume change, with e from about 1.25 to 0.5, but was reverted to a more pronounced form by xanthan gum, with e from 1.5 to 1.32, 1.32 to 0.49, and 0.49 to 0.34 in the three stages, respectively. The consolidation behavior of the soil was largely unaffected by the addition of biopolymers such that the saturated hydraulic conductivity decreased from 10⁻⁹ m/s to 10⁻¹² m/s over a void ratio decrease from 1.1 to 0.6. At a seating stress of 5 kPa, the swelling potential (7.8%) of the soil slightly decreased to 6.9% due to the addition of chitosan but increased to 9.4% and 12.2% with guar gum and xanthan gum, respectively. The use of chitosan and guar gum will allow the compaction of the investigated expansive soil on the dry side of optimum. Full article

Are there any correlations between land use and the associated prices charged for the soil? What is the significance of green infrastructure and what is the significance of public facilities and transport? For the analysis of the data, various methods of factor reduction and analysis were used to identify a multiple regression model that explained the price building. An effect was found between the pricing of the standard land reference value (SLRV), number of trees and distance to allotments. Summarizing the results, less than 231 trees in an SLRV zone causes an SLRV increase, the opposite is the case with a larger number of trees. The more accessible an allotment garden is (in terms of distance <421 m), the lower the SLV in the adjacent area. If the distance that must be covered to the allotment garden increases, the SLRV of the area increases. However, a more significant influence on the SLRV was concluded by the market economy variables. In summary, the present study indicates that (a) a uniform evaluation matrix for the SLRV should be created, and (b) the present subjective land assessments by the relevant experts should be complemented through targeting further training in the ecologically oriented planning context. Full article

Buried charges pose a serious threat to both civilians and military personnel. It is well established that soil properties have a large influence on the magnitude and variability of loading from explosive blasts in buried conditions. In this study, work has been undertaken to improve techniques for processing pressure data from discrete measurement apparatus; this is performed through the testing of truncation methodologies and the area integration of impulses, accounting for the particle size distribution (PSD) of the soils used in testing. Two experimental techniques have been investigated to allow for a comparison between a global impulse capture method and an area-integration procedure from a Hopkinson Pressure Bar array. This paper explores an area-limiting approach, based on particle size distribution, as a possible approach to derive a better representation of the loading on the plate, thus demonstrating that the spatial distribution of loading over a target can be related to the PSD of the confining material. Full article

Globally, soil acidification is becoming a serious environmental and ecological concern, posing a major threat to ecosystem functions and services. In order to clarifying the acidification mechanism, evaluating acidification risk, and reconditioning soil acidification, the effects of acidification on clay mineral composition and soil surface properties should be evaluated. In this study, the surface charge, specific surface area (SSA), species and content of clay minerals were investigated using the ion adsorption method, methylene blue method, and X-ray diffraction (XRD) for brown soil samples, which collected from Muping, Shandong Province, China. The results showed that the clay mineral species and content varied with the degree of acidification. A small amount of montmorillonite was found in weakly acidic soils, and gibbsite was found in strongly acidic soils. Furthermore, although illite, kaolinite, vermiculite, and chlorite were commonly found in soils with different acidification degrees, their content differed. The negative charge (CEC₈.₂), permanent negative charge (CEC_P), variable negative charge (CEC_V), and SSA values decreased with increasing acidification, while anion exchange capacity values (AEC) decreased. The change of CEC_V was caused by soil organic matter, and the change of CEC_P was caused by illite content, which accounted for the largest proportion in clay minerals of brown soil. Full article

This study establishes that processed zero valent iron can be pelletised and used to desalinate water. The pellets desalinate water using a zero-order reaction, where: product water salinity = −[a][Reaction Time] + Feed Water Salinity. Desalination using the pellets requires no onsite energy, no onsite infrastructure, and produces no reject brine. Potential applications for the pellets, include desalination of saline impoundments, desalination of agricultural water, desalination of irrigation water, desalination of irrigated salinized soils, and aquifer desalination. The examples demonstrate 30% to 60% desalination for saline feed water within the salinity range of 4 to 10 g L⁻¹. The product water has a low outcome variability for a specific pellet charge. The achievable desalination increases as the pellet weight: water volume ratio increases. The pellets can also be used for water purification, wastewater desalination, treatment of domestic wastewater, treatment of industrial wastewater, treatment of livestock feed water, treatment of oil field and mining wastewater, water purification to allow reuse, and the treatment of polluted soils. This study addresses the manufacture of the pellets, their effectiveness in desalinating water, and the outcome variability associated with desalination. Full article

This work evaluates phosphate and nitrate ion adsorption from aqueous solutions on calcined adsorbent substrates of variable charge, prepared from three granulometric fractions of an oxidic lithological material. The adsorbent material was chemically characterized, and N₂ gas adsorption (BET), X-ray diffraction, and DTA techniques were applied. The experimental conditions included the protonation of the beds with HCl and H₂SO₄ and the study of adsorption isotherms and kinetics. The lithological material was moderately acidic (pH 5) with very little solubility (electrical conductivity 0.013 dS m⁻¹) and a low cation exchange capacity (53.67 cmol (+) kg⁻¹). The protonation reaction was more efficient with HCl averaging 0.745 mmol versus 0.306 mmol with H₂SO₄. Likewise, the HCl-treated bed showed a better adsorption of PO₄⁻³ ions (3.296 mg/100 g bed) compared to the H₂SO₄-treated bed (2.579 mg/100 g bed). The isotherms showed great affinity of the PO₄⁻³ ions with the oxide surface, and the data fit satisfactorily to the Freundlich model, suggesting a specific type of adsorption, confirmed by the pseudo-second-order kinetic model. In contrast, the nitrate ions showed no affinity for the substrate (89.7 µg/100 g for the HCl-treated bed and 29.3 µg/100 g bed for the H₂SO₄-treated bed). Amphoteric iron and aluminum oxides of variable charges present in the lithological material studied allow for their use as adsorbent beds as an alternative technique to eliminate phosphates and other ions dissolved in natural water. Full article

In this paper, a deep-learning model is proposed as a viable approach to optimize the information on soil parameters and agricultural variables’ effect in cotton cultivation, even in the case of small datasets. In this study, soil is analyzed to reduce the planting costs by determining the various combinations of soil components and nutrients’ precise amounts. Such factors are essential for cotton cultivation, since their amounts are often not precisely defined, and especially traditional farming methods are characterized by excessive distribution volumes producing significant economic and environmental impact. Not only can artificial intelligence decrease the charges, but it also increases productivity and profits. For this purpose, a deep learning algorithm was selected among other machine learning algorithms by comparison based on the accuracy metric to build the predictive model. This model gets the combination of the factors amounts as input and predicts whether the cotton growth will be successful or not. The predictive model was built by this algorithm based on 13 physical and chemical factors has 98.8% accuracy. Full article

The sorption behavior of 2,4-dichlorophenoxyacetic acid (2,4-D) in the abundant agricultural volcanic ash-derived soils (VADS) is not well understood despite being widely used throughout the world, causing effects to the environment and human health. The environmental behavior and risk assessment of groundwater pollution by pesticides can be evaluated through kinetic models. This study evaluated the sorption kinetics and 2,4-D sorption–desorption in ten VADS through batch sorption experiments. Differences in the sorption extent for the fast and slow phases was observed through the $\mathrm{IPD}$ model where 2,4-D sorption kinetics was controlled by external mass transfer and intra organic matter diffusion in Andisols (${\mathrm{C}}_1$ ≠ 0). We confirmed from the spectroscopic analysis that the carboxylate group directly drives the interaction of 2,4-D on Andisol soil. The MLR model showed that $IEP$, $F{e}_{DCB}$, and $pH\times Silt$ are important soil descriptors in the 2,4-D sorption in VADS. The Freundlich model accurately represented sorption equilibrium data in all cases ($K_f$ values between 1.1 and 24.1 µg^1−1/n mL^1/ng⁻¹) with comparatively higher sorption capacity on Andisols, where the highest hysteresis was observed in soils that presented the highest and lowest $OC$ content ($\mathrm{H}$ close to 0). Full article

Surface soil moisture (SSM) is a key variable for many environmental studies, including hydrology and agriculture. Synthetic aperture radar (SAR) data in the C-band are widely used nowadays to estimate SSM since the Sentinel-1 provides free-of-charge C-band SAR images at high spatial resolution with high revisit time, whereas the use of L-band is limited due to the low data availability. In this context, the main objective of this paper is to develop an operational approach for SSM estimation that mainly uses data in the C-band (Sentinel-1) with L-bands (ALOS/PALSAR) as additional data to improve SSM estimation accuracy. The approach is based on the use of the artificial neural networks (NNs) technique to firstly derive the soil roughness (Hrms) from the L-band (HH polarization) to then consider the L-band-derived Hrms and C-band SAR data (VV and VH polarizations) in the input vectors of NNs for SSM estimation. Thus, the Hrms estimated from the L-band at a given date is assumed to be constant for a given times series of C-band images. The NNs were trained and validated using synthetic and real databases. The results showed that the use of the L-band-derived Hrms in the input vector of NN in addition to C-band SAR data improved SSM estimation by decreasing the error (bias and RMSE), mainly for SSM values lower than 15 vol.% and regardless of Hrms values. Based on the synthetic database, the NNs that neglect the Hrms underestimate and overestimate the SSM (bias ranges between −8.0 and 4.0 vol.%) for Hrms values lower and higher than 1.5 cm, respectively. For Hrms <1.5 cm and most SSM values higher than 10 vol.%, the use of Hrms as an input in the NNs decreases the underestimation of the SSM (bias ranges from −4.5 to 0 vol.%) and provides a more accurate estimation of the SSM with a decrease in the RMSE by approximately 2 vol.%. Moreover, for Hrms values between 1.5 and 2.0 cm, the overestimation of SSM slightly decreases (bias decreased by around 1.0 vol.%) without a significant improvement of the RMSE. In addition, for Hrms >2.0 cm and SSM between 8 to 22 vol.%, the accuracy on the SSM estimation improved and the overestimation decreased by 2.2 vol.% (from 4.5 to 2.3 vol.%). From the real database, the use of Hrms estimated from the L-band brought a significant improvement of the SSM estimation accuracy. For in situ SSM less than 15 vol.%, the RMSE decreased by 1.5 and 2.2 vol.% and the bias by 1.2 and 2.6 vol.%, for Hrms values lower and higher than 1.5 cm, respectively. Full article

Thousands of tons of zeolitic materials are used yearly as soil conditioners and components of slow-release fertilizers. A positive influence of application of zeolites on plant growth has been frequently observed. Because zeolites have extremely large cation exchange capacity, surface area, porosity and water holding capacity, a paradigm has aroused that increasing plant growth is caused by a long-lasting improvement of soil physicochemical properties by zeolites. In the first year of our field experiment performed on a poor soil with zeolite rates from 1 to 8 t/ha and N fertilization, an increase in spring wheat yield was observed. Any effect on soil cation exchange capacity (CEC), surface area (S), pH-dependent surface charge (Qv), mesoporosity, water holding capacity and plant available water (PAW) was noted. This positive effect of zeolite on plants could be due to extra nutrients supplied by the mineral (primarily potassium—1 ton of the studied zeolite contained around 15 kg of exchangeable potassium). In the second year of the experiment (NPK treatment on previously zeolitized soil), the zeolite presence did not impact plant yield. No long-term effect of the zeolite on plants was observed in the third year after soil zeolitization, when, as in the first year, only N fertilization was applied. That there were no significant changes in the above-mentioned physicochemical properties of the field soil after the addition of zeolite was most likely due to high dilution of the mineral in the soil (8 t/ha zeolite is only ~0.35% of the soil mass in the root zone). To determine how much zeolite is needed to improve soil physicochemical properties, much higher zeolite rates than those applied in the field were studied in the laboratory. The latter studies showed that CEC and S increased proportionally to the zeolite percentage in the soil. The Qv of the zeolite was lower than that of the soil, so a decrease in soil variable charge was observed due to zeolite addition. Surprisingly, a slight increase in PAW, even at the largest zeolite dose (from 9.5% for the control soil to 13% for a mixture of 40 g zeolite and 100 g soil), was observed. It resulted from small alterations of the soil macrostructure: although the input of small zeolite pores was seen in pore size distributions, the larger pores responsible for the storage of PAW were almost not affected by the zeolite addition. Full article