Increasing drought stress due to climate warming has triggered various negative impacts on plantations in dryland areas, including growth reduction, crown dieback, and even tree mortality, with unavoidable consequences for forest ecosystems. However, how drought stress progressively led to the damage process from growth reduction to mortality for mature trees remains largely unclear, especially its varying soil moisture thresholds. Here we selected mature trees in larch (Larix principis-rupprechtii) plantations in the dryland areas of northwest China, and monitored the progressive tree responses in an extreme summer drought event in 2021, including transpiration, radial growth, leaf area index, discoloration, defoliation, crown dieback and tree mortality. The results showed strong responses of larch trees to summer drought, such as large stem shrinkage, dramatic decrease in transpiration and leaf area index, and obvious discoloration, defoliation, crown dieback and tree mortality at some sites. The intensity of tree responses mainly depended on soil moisture rather than meteorological factors and there were strong relationships between tree responses and relative soil water content (RSW) of 0-60 cm layers. Based on the trees responded to RSW, five soil drought stress levels or progressive mortality stages and their corresponding RSW thresholds were determined as following: no detectable hydraulic limitations (RSW>0.7, Level I), persistent stem shrinkage and onset of transpiration reduction (0.45<= 0.7, Level II), onset of slight discoloration and defoliation (0.35<= 0.45, Level III), onset of crown dieback and tree mortality (0.25<= 0.35, Level IV), and severe defoliation, crown dieback and tree mortality (RSW <= 0.25, Level V). This study showed that the trees responded to climatic drought were strongly regulated by soil moisture and thus were strongly site-specific. These findings will help to evaluate the degree and spatio-temporal distribution of tree damage and mortality in plantations under increasing climatic drought, particularly in dryland areas.
The intrusion of petroleum into soil ecosystems causes severe environmental damage. A synergistic plant-microbe-electrochemical soil remediation technology offers a strategic and eco-friendly solution to address this issue. However, the significant mass transfer resistance in soil poses a major limitation for long-distance site remediation. This research introduces a novel technique that leverages water circulation driven by plant transpiration to facilitate the long-distance migration, adsorption, and electrochemical degradation of hydrocarbons. Experimental results demonstrate that the incorporation of Iris tectorum, polyurethane sponge (as an electrode support matrix), and water-retaining agents significantly enhanced soil water circulation, enabling the migration of soluble organic carbon over distances of up to 60 cm. Additionally, the application of a weak voltage (0.7 V) to the electrode further improved total organic carbon (TOC) removal, achieving a reduction of 193 +/- 71 mg/L. After 42 days of remediation, hydrological circulation accelerated the degradation of n-alkanes and aromatics, with removal efficiencies reaching 57 % and 44 %, respectively, within the 20-60 cm range in the microbial electrochemical cell (MEC) group. The functional microbiota, enriched with electroactive microorganisms, was effectively cultivated on the anode, with the total abundance of potential hydrocarbon-degrading bacteria increasing by 42 % compared to the control. Furthermore, a scalable configuration has been proposed, offering a novel perspective for multidimensional ecological soil remediation strategies.
The construction industry faces significant challenges, including the urgent need to minimize environmental impact and develop more efficient building methods. Additive manufacturing, commonly known as 3D-printing, has emerged as a promising solution due to its advantages, such as rapid fabrication, design flexibility, cost reduction, and enhanced safety. This technology enables the creation of structures from digital models through automated layering, presenting opportunities for mass production with innovative materials and architectural designs. This article focuses on developing eco-friendly earthen-based materials stabilized with 9 % cement and 2 % rice husk (RH) for large-scale 3D-printed construction. The raw materials were characterized using geotechnical tests for soil, water absorption tests for natural fibers, and SEM-EDS to examine their microstructure and elemental composition. Key properties such as rheology, printability (pumpability and extrudability), buildability, and compressive strength were evaluated to ensure the material's optimal performance in both fresh and hardened states. By utilizing locally sourced materials such as soil and rice husk, the mixture significantly reduces environmental impact and production costs, making it a sustainable alternative for large-scale 3D-printed construction. The material was integrated into architectural and digital fabrication techniques to construct a bioinspired housing prototype showcases the practical application of the developed material, demonstrating its scalability, adaptability, and suitability for innovative and costeffective real housing solutions. The article highlights the feasibility of using earthen-based materials for sustainable 3D-printed housing, thereby opening new possibilities for advancing greener construction practices in the future.
The tsunami in March 2011 heavily damaged the Pinus thunbergii Parlatore erosion-control coastal forests of northeastern Japan. The restoration is in process but has been challenged by waterlogging resulting from soil compaction of artificial growth bases. In this study, a pot experiment was conducted to elucidate the waterlogging responses of two-year-old P. thunbergii seedlings in terms of waterlogging duration. Three waterlogging durations were set (7 days, 17 days, and 32 days, water table at soil surface) during August, followed by a waterlogging-free recovery period (28 days) in September. In this experiment, the responses of both above- and belowground organs during waterlogging and after the release from waterlogging were elucidated, focusing on parameters, such as transpiration and photosynthesis rates, as well as fine root growth and morphology. As a result, we found that under the conditions of our experiment, if the waterlogging duration is within 17 days, P. thunbergii seedlings can recover physiological activity in about a week; however, if the waterlogging duration is over 32 days, recovery after the release from waterlogging largely varied among seedlings. For the seedlings that could recover, recovery took at least 2 weeks, which required new fine root growth. In cases where the damage was irreversible, seedlings showed an overall decline. These results suggest that it is important to manage the waterlogging conditions so that P. thunbergii seedlings can recover without prolonged negative effects.
Agricultural drought is a natural and damaging phenomenon that is especially harmful to rainfed agriculture. It occurs when there is insufficient soil moisture in the root zone for plants to survive between two rainfall events. In the absence of soil moisture, a variety of losses, including soil evaporation and plant transpiration, cause an imbalance between water supply and water loss. An evapotranspiration-based index was used here to assess agricultural drought. We applied this framework to a less studied area near Fariman City in the northeast part of IRAN. Two time periods were selected for comparison including 2015 and 2016 spring season that are associated with dry and wet conditions, respectively. To calculate the drought index, actual and potential evapotranspiration were estimated by the Surface Energy Balance Algorithm for Land (SEBAL), the upgraded Priestley-Taylor method and remote sensing data. The Relative Water Deficit Index (RWDI) illustrated that lack of water in rainfed lands and pastures for the dry period was obtained from 80 to 100 percent, whereas this was between 50 and 70% for the wet period.
The extensive use of petroleum-based plastics has resulted in critical energy and environmental challenges, driving the pursuit of sustainable and biodegradable bioplastics as ideal alternatives. However, the development of functional bioplastics with superior mechanical strength, water stability, and thermal stability remains a formidable challenge. Herein, inspired by the nacre, a cellulose-based bioplastic was designed with a unique layered architecture and enhanced interfacial interactions,achieved through the self-assembly of carboxymethyl cellulose (CMC) and nano-montmorillonite, while simultaneously forming a chemically and physically double-crosslinked network under the action of TiO2 nanoparticles and citric acid. The resulting bioplastic demonstrated excellent mechanical performance, with the tensile strength reaching 106.83 MPa, representing a 220.09 % improvement over pure CMC-based bioplastic and surpassing the tensile strength of other CMC-based films. Alongside mechanical prowess, it exhibited exceptional water resistance (water absorption reduced to 42.88 %), thermal stability and UV shielding. Furthermore, it was biodegradable and environmentally benign, capable of achieving complete degradation in the soil within three months. This biomimetic strategy provided a novel approach for developing competitive cellulose-based bioplastics, offering a promising alternative to petroleum-derived plastics for everyday applications.
The study applies the Minimum Impact Design Standards (MIDS) calculator to assess urban trees' effectiveness in reducing surface runoff along five flood-prone streets in Hue City, analyzing evapotranspiration, rainfall interception, and infiltration, along with Leaf Area Index (LAI), Canopy Projection (CP), tree pit size, and soil structure. Results show that urban trees retain 1,132.39 m(3) of stormwater, but runoff reduction is not solely dependent on tree quantity. Although tree numbers vary 1.56 to 3.8 times, runoff reduction differs only 1.39 to 1.79 times. Evapotranspiration plays the largest role, contributing 2.8 times more than interception and 2.6 times more than infiltration. Small tree pits and compacted soil limit infiltration, while pruning and height reduction decrease Pc and LAI, reducing flood mitigation benefits. Annual storm damage further weakens this capacity. To enhance effectiveness, the study suggests prioritizing storm-resistant species, increasing tree numbers, enlarging tree pits, and using structured soil. Implementing these measures can improve urban flood resilience and maximize trees' hydrological benefits. Future research should focus on optimizing tree selection and planting strategies for long-term flood management in urban areas, ensuring sustainable solutions that enhance both stormwater control and environmental resilience.
This study investigates the seismic performance of a theoretical hospital building designed as a Fixed-Base (FB) structure according to TSC-2018 (Turkish Seismic Code) and evaluates its behavior under three scenarios: FixedBase (FB), Soil-Structure Interaction (SSI), and Base-Isolated (SSI+ISO). The study employs Nonlinear Time History Analysis (NLTHA) using scaled acceleration records, including one from the 2023 Maras, earthquake. Structural performance is assessed based on maximum roof displacements, interstory drift ratios (IDR), and isolator displacements. Results show that base isolation systems significantly reduce drift demands and roof displacements, keeping the structure within slight damage limits even under extreme seismic loads. In contrast, SSI effects amplify interstory drift demands, increasing the likelihood of exceeding moderate damage thresholds. The analysis highlights the Maras, Education and Research Hospital, which suffered severe damage and became non-operational during the 2023 Kahramanmaras earthquake. This outcome underscores the limitations of fixedbase designs in regions with soft soil conditions and the necessity of incorporating base isolation systems to improve seismic resilience. The findings emphasize the importance of mandatory adoption of base isolation systems in hospital designs, proper consideration of SSI effects, and the retrofitting of existing hospital buildings to meet modern seismic code requirements (TSC-2018) and prevent similar failures in future seismic events.
In geotechnical engineering, bioinspired ideas such as snakeskin-inspired solutions for frictionally anisotropic continuum materials have been receiving increased attention due to their ability to create resilient and efficient geomaterial-continuum interfaces. Several studies have found that snakeskin-inspired continuum surfaces mobilise significant frictional anisotropy with different soils. However, studies on the effect of snakeskin-inspired patterns on other continuum geomaterials, such as rock surfaces, which can have promising applications like friction rock bolts, are rare. This study aims to address this gap by investigating the effect of snakeskin-inspired patterns on the shear behaviour of soft rocks, which is simulated by Plaster of Paris (PoP). For this purpose, snakeskin-inspired continuum surfaces with surface patterns inspired from the ventral scales of a snake with five different scale angles (10 degrees, 13 degrees, 16 degrees, 19 degrees and 22 degrees) were 3D printed with Polylactic Acid (PLA) polymer using a Fused Filament Fabrication (FFF) 3D printer. The interface shear behaviour of these surfaces with PoP was investigated using a customised interface shear testing apparatus under three normal loads: 1000 N, 2000 N and 3000 N. The results of the tests confirm that snakeskin-inspired patterns on continuum material mobilise substantial anisotropic friction and that the interface shear response depends on the shearing direction and the scale angle. The shearing direction significantly affects the peak and post-peak shear behaviour and the strain softening behaviour of the snakeskin-inspired interfaces. The study yields promising results for applying snakeskin-inspired patterns to create rock bolts with direction-dependent friction and enhances the existing knowledge in bioinspired geotechnics.
Mercury (Hg) poses significant risks to human health, the environment, and plant physiology, with its effects influenced by chemical form, concentration, exposure route, and organism vulnerability. This study evaluates the physiological impacts of Hg on Handroanthus impetiginosus (Ip & ecirc; Roxo) seedlings through SPAD index measurements, chlorophyll fluorescence analysis, and Hg quantification in plant tissues. Four-month-old seedlings were exposed for eight days to distilled water containing Hg at 0, 1, 3, 5, and 7 mg L-1. The SPAD index decreased by 28.17% at 3, 5, and 7 mg L-1, indicating reduced photosynthetic capacity. Chlorophyll a fluorescence analysis revealed a 50.58% decline in maximum efficiency (Fv/Fm) and a 58.33% reduction in quantum yield (Phi PSII) at 7 mg L-1, along with an 83.04% increase in non-photochemical quenching (qn), suggesting oxidative stress and PSII damage. Transpiration decreased by 26.7% at 1 mg L-1 and by 55% at 3, 5, and 7 mg L-1, correlating with Hg levels and leaf senescence. Absorption, translocation, bioconcentration, and bioaccumulation factors varied among treatments. Hg accumulated mainly in stems (40.23 mu g g-1), followed by roots (0.77 mu g g-1) and leaves (2.69 mu g g-1), with limited translocation to leaves. These findings highlight Hg's harmful effects on H. impetiginosus, an ecologically and commercially valuable species, addressing a gap in research on its Hg tolerance and phytoremediation potential.