Search Results (13,158)

Phytophthora cinnamomi Rands, an oomycete pathogen of global relevance, is a major driver of cork oak (Quercus suber L.) decline and mortality in Mediterranean forests. Its management remains challenging in multifunctional landscapes where forestry and agriculture intersect, like in Mediterranean oak dehesas. Conventional fungicides are used against P. cinnamomi, but their negative environmental impacts underscore the need for alternative management in agroforestry systems. This study evaluated whether a commercially available microbial biostimulant, VESTA, enhances physiological performance and mitigates pathogen pressure in Q. suber. Seedlings were inoculated with P. cinnamomi and treated with the bioinoculant via fertigation or watering to substrate saturation, under controlled greenhouse conditions. Plant physiological parameters and soil oomycete inoculum concentrations were measured to assess treatment efficacy. Both application methods significantly improved physiological performance in inoculated and mock-inoculated plants. Photosynthesis, stomatal regulation, and water balance were most affected. Quantitative PCR analyses revealed a strong pathogen reduction, with DNA concentrations approximately tenfold lower in treated substrates (~0.001 ng mL⁻¹) than untreated controls (~0.011 ng mL⁻¹). Overall, the product enhanced Q. suber resilience by improving plant physiological responses and reducing pathogen abundance, supporting its potential as a bio-based tool for nurseries and restoration in Mediterranean ecosystems. Field studies are needed to validate these findings under natural variability and optimize long-term application strategies. Full article

Electrokinetic remediation (EKR) was evaluated in naturally contaminated vineyard soils to assess copper redistribution, treatment redistribution efficiency, and changes in copper fractions across contrasting soil pH conditions. Ten vineyard soils (five acidic, five alkaline) were subjected to a 30-day ex situ EKR experiment under a constant electric field. Total copper content was measured in the anode, cathode, and inter-electrode zones, while copper fractions were quantified only in electrode zones exhibiting the most pronounced post-remediation decrease in total copper. The findings demonstrate that the EKR process generated distinct, soil-type-dependent gradients in copper mobility. In acidic soils, copper exhibited pronounced central-zone accumulation with notable depletion toward the anode, whereas in alkaline soils, the lowest concentrations consistently occurred near the cathode and increased toward the anode. Notably, one slightly alkaline soil displayed the highest redistribution efficiency (43.0%), underscoring the strong influence of soil chemistry on EKR performance. Redistribution efficiencies averaged 29.5% in acidic soils and 12.8% in alkaline soils, although localized acidification enabled notably higher redistribution in highly contaminated samples. These trends reflected on copper fractions: acidic soils showed enhanced release from Fe/Mn oxides and carbonates, while alkaline soils experienced stronger short-term mobilization driven by cation competition and dissolution of less stable oxide phases. Fractionation results indicated that the Fe/Mn oxide-bound fraction was the most susceptible to electromigration, while both acidic and alkaline soils ultimately shifted copper toward less extractable operational fractions. Full article

In Northeast China’s degraded croplands, nitrate (NO₃⁻-N) leaching is the dominant pathway for fertilizer-nitrogen (N) loss, which presents an increasing threat to the quality of groundwater. Conservation tillage, defined as no-tillage (NT) and straw retention, is a widely adopted management strategy to maintain cropland fertility in the black soil (BS) regions. At present, however, the impact of shifting from conventional to conservation tillage on the vertical distribution and regulatory mechanisms of NO₃⁻-N derived from applied fertilizer-N (F_NO3) remains poorly understood. Based on a 12-year field experiment, we integrated ¹⁵N-tracing field monitoring with ¹⁵N-paired-labeling incubation to quantify the vertical migration of F_NO3 into deep soil profiles, and specify the dominant processes regulating N retention and supply. Across the tested BS croplands, total NO₃⁻-N production rates (4.06–6.58 mg N kg⁻¹ soil day⁻¹) were faster than their consumption rates (0.36–0.92 mg N kg⁻¹ soil day⁻¹), leading to a net accumulation of NO₃⁻-N, and implying a potential for leaching of NO₃⁻-N, from the perspective of substrate availability. The results of the field ¹⁵N micro-plot experiment also indicated that, by maize maturity in the first growing season, an average of 7.5% of F_NO3 had migrated to the 80–100 cm soil layer. During the following two growing seasons, the maximum accumulation of F_NO3 had shifted downward to 140–160 cm and 180–220 cm, respectively. Such a pattern, particularly in light of the increased extreme precipitation in the studied regions, raises clear concerns about NO₃⁻-N leaching losses. Compared with conventional management, no-tillage with full-rate straw mulching decreased net rates of NO₃⁻-N production from 6.22 to 3.14 mg N kg⁻¹ soil day⁻¹. This reduction resulted from a decline in the gross oxidation of NH₄⁺-N to NO₃⁻-N (from 6.39 to 3.70 mg N kg⁻¹ soil day⁻¹) and an increase in DNRA (from 0.35 to 0.85 mg N kg⁻¹ soil day⁻¹), which collectively delayed the downward transport of F_NO3. Conservation tillage also increased the gross rate of heterotrophic nitrification (from 0.19 to 0.36 mg N kg⁻¹ soil day⁻¹) and its proportion relative to total nitrification (from 2.8% to 8.9%). Despite this shift, autotrophic nitrification remained the dominant process for NO₃⁻-N production in the tested BS croplands, likely due to a pH constraint on heterotrophic nitrification. With the increasingly widespread promotion of conservation tillage for soil fertility improvement, heterotrophic nitrification warrants greater attention, particularly in BS regions where pH < 6.5 and C/N contents are relatively high. Collectively, our findings provide a scientific basis for tailoring tillage practices to maintain sustainable agriculture in Northeast China. Full article

Soil salinity and nutrient availability are major constraints affecting crop productivity, soil quality, and agroecosystem sustainability, particularly in coastal regions vulnerable to seawater intrusion. This study provides a comprehensive spatial and temporal assessment of soil properties and quality dynamics on Hainan Island by integrating field observations and multi-temporal remote sensing (RS) datasets. In 2024, a total of 152 sampling sites were surveyed, with three topsoil soil samples collected at each location. Multi-year RS data (2024–2021), including soil salinity reflectance indices (SRSI and SI), the Normalized Difference Vegetation Index (NDVI), and land use and land cover (LULC), were analyzed to evaluate temporal and spatial variability. The soil fertility index was calculated using alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK), soil pH, and soil organic matter (SOM). The soil quality index was calculated using the same parameters with the addition of chromium (Cr) to account for potential heavy metal contamination. Furthermore, in this study the Inverse Distance Weighting (IDW) method was used for spatial distribution maps of soil properties and other indices. The results indicated that soils were predominantly acidic (pH < 6.0) with generally low electrical conductivity (0.01–0.53 mS cm⁻¹) across inland areas, whereas higher salinity levels (2.28–5.31 mS cm⁻¹) were observed in southern and eastern coastal zones, suggesting potential seawater intrusion. Nutrient concentrations ranged from 60.1 to 150 mg kg⁻¹ (AN), 4 to 332 mg kg⁻¹ (AP), and 50.1 to 100 mg kg⁻¹ (AK). NDVI values (0.70–0.94) indicated high vegetation density over most agricultural landscapes. Significant positive correlations were observed between soil EC and the SRSI (r = 0.781) and SI (r = 0.663; p < 0.01), demonstrating the reliability of RS-derived indices for salinity assessment. The integrated indicator-based framework developed in this study provides a scientific basis for precision agriculture, soil health monitoring, and sustainable land management in coastal agroecosystems. Full article

This study investigated how fertilization regimes and ridge furrow planting patterns influence the soil nutrient conditions and microbial taxonomic composition and function in the rhizosphere of spring maize in Northeast China. Three treatments were compared: CK (compound fertilizer, small ridge), KF (formula fertilization, small ridge), and BMP (formula fertilization, large double-row ridge). High-throughput sequencing was used to characterize the soil bacterial and fungal community composition and diversity. The results showed that the combination of formula fertilizer and wide-ridge cultivation synergistically improved soil physicochemical properties and significantly increased maize yield (p < 0.05). Compared with CK, both BMP and KF significantly improved the composition and diversity of microbial communities. Notably, the BMP treatment increased the relative abundances of Ascomycota and Basidiomycota—key decomposers of soil organic matter, lignin, and cellulose—which suggested enhanced nutrient cycling potential under this integrated management practice. Among the three treatments, BMP (N:P₂O₅:K₂O = 1:2:1, 130 cm wide-ridge double-row planting) achieved the highest maize yield (859 ± 14 kg ha⁻¹), representing an 11.0% increase over conventional practices (CK, 774 ± 13 kg ha⁻¹). We propose that integrating optimized fertilization with ridge configuration is an effective strategy for improving soil quality, microbial functionality, and crop productivity in Northeast China’s black soil region. Full article

Radioactive contaminations in soil, which originate from nuclear power production, nuclear weapon testing, or uncontrolled release, are of great environmental concern. One of the major fission product contaminants is ⁹⁰Sr, whose high mobility demands a method to track contamination pathways and remediation processes. Positron emission tomography (PET) is a valuable tool for the required studies. As a β⁻/γ-emitter, ⁹⁰Sr is not suitable for PET, which requires β⁺-emitters. As an alternative, ⁸³Sr, with a 12% intensity of β⁺-emission and a half-life of 32.4 h, is an appropriate PET substitute for ⁹⁰Sr. We produced ⁸³Sr with an enriched target of [⁸⁵Rb]RbCl in a ⁸⁵Rb(p,3n)⁸³Sr reaction. The target material was bombarded with 36.22 MeV protons (ø 1.78 µA, 315 min), at a solid target station at the cyclotron U-120M (NPI CAS). The irradiated target (1.5 GBq) was dissolved in water, evaporated to dryness, redissolved in nitric acid, and transferred onto a Sr-selective cartridge (Sr-SpecTM, TRISKEM, France). Following target material wash out, ⁸³Sr elution with water, solvent evaporation, and reformulation (in dilute nitric acid) yielded 1.2 GBq (82% radiochemical extraction efficiency, non-decay-corrected) of an ⁸³Sr-solution. The easy and fast method is able to produce non-carrier-added ⁸³Sr with high radionuclidic purity. Full article

Promoting the agricultural recycling of biogas slurry (BS) is crucial for sustainable development, yet its long-term ecological impacts remain unclear. Through a multi-year field trial in a sugarcane system, this study examined the effects of BS application (0, 3, and 6 years) on the soil properties, bacterial communities, and functional genes for C, N, P, and S cycling. The results revealed distinct two-phase patterns of changes in soil properties, microbial communities, and functional genes. Short-term (3-year) application induced a “disturbance” phase, characterized by significant acidification (pH decreased by 17.91%), a surge in nitrate-N (increased by 757.27%), and a transient decline in bacterial richness. Long-term (6-year) application drove a “functional restructuring” phase, reversing acidification and significantly increasing soil organic matter (29.05%) and total nitrogen (TN) (20.81%). Bacterial richness recovered, and community composition distinctively restructured. Functional gene analysis revealed shifts in gene abundance that transitioned from high abundance in the short term to a new balance favoring processes like N fixation. Co-occurrence network analysis indicated that this functional shift was associated with core microbial modules (e.g., Firmicutes) and changes in soil pH and SOM. This study suggests that, although short-term application causes significant adjustments, sustained and appropriate BS application can ultimately enhance soil fertility and promote a functionally reorganized state by reshaping microbial interaction networks. It presents a microbial ecological basis for the safe and sustainable use of BS in circular agriculture. Full article

Cunninghamia lanceolata Lamb. occupies a significant role in artificial forests globally, making its sustainable management crucial for terrestrial forest ecology. We experimentally determined soil physicochemical properties and the shrub and herb diversity of different age classes of Cunninghamia lanceolata plantations in Southwest China in 2023. The Mantel tests, RDA, and PLS-SEM were used to analyze the effects of stand factors on soil fertility and shrub and herb diversity. Shrub and herb diversity, as well as soil physicochemical properties, vary significantly across age classes in Cunninghamia lanceolata plantations. The maximum values of organic carbon, total nitrogen, total phosphorus, and available silicon were observed in the mature forest (36.62 g/kg, 1.90 g/kg, 0.53 g/kg, and 84.33 mg/kg, respectively), while the minimum values were found in the middle-aged forest (17.77 g/kg, 0.81 g/kg, 0.34 g/kg, and 53.70 mg/kg). TPH was the most influential stand factor. TBH was strongly correlated with RDA1 (r = 0.821, p < 0.001); soil organic carbon, total nitrogen, total phosphorus, and available silicon were negatively correlated with stand density. In this study, we propose a detailed age class-based thinning plan with strong implementability: cultivating large-diameter timber, maintaining soil fertility and understory plant diversity, and being friendly to forest farm management personnel. This approach could enhance biodiversity and ecosystem stability in Cunninghamia lanceolata plantations and serves as a reference for the sustainable management and operation of the Cunninghamia lanceolata forest ecosystem. Full article

Response of large-diameter rock-socketed piles subjected to lateral loads is a critical issue in foundation design for bridges, high-rise buildings, and offshore platforms. Although the p-y curve method is commonly used for pile analysis in soil, its direct application to rock-socketed piles remains challenging due to the significant differences in mechanical properties between rock and soil. This study investigates the initial stiffness and stress distribution around the large-diameter rock-socketed piles under lateral loads. Based on the Serrano method, the Hoek–Brown strength criterion is extended to derive calculation formulas for rock cohesion and internal friction angle considering confining pressure effects. A three-dimensional numerical model was established using FLAC3D to analyze stress distribution, pile displacement, and p-y curves at different depths. Distribution functions for normal stress and shear stress around the pile were developed. Parameter sensitivity analysis reveals that the initial stiffness of p-y curves is primarily influenced by rock deformation modulus and pile diameter, while rock strength parameters and pile length effects are negligible. Empirical formulas for predicting initial stiffness of p-y curves were proposed through regression analysis. These results serve as both a theoretical basis and an engineering reference for the design and analysis of large-diameter rock-socketed piles under lateral loading. Full article

Photovoltaic (PV) performance in desert environments is significantly hindered by soiling and partial shading. To bridge the gap in empirical data for extreme Saharan conditions, this study presents a novel techno-economic assessment of uniform horizontal shading (UHS) specifically conducted in Mauritania. Controlled outdoor experiments were performed using a 250 W crystalline silicon PV module and a PVPM 2540C I–V curve tracer, applying progressive shading levels from 2.5% to 20%. The novelty of this work lies in the integration of high-resolution experimental I–V/P–V characterization with a localized techno-economic model for five pre-commercial PV plants. It was observed that PV modules are exceptionally sensitive to shading; specifically, a mere 10% shaded area leads to a catastrophic 90% drop in power and current, while the voltage remains remarkably stable. Thermographic analysis further validates the thermal gradients and bypass diode functionality. By quantifying the financial impacts, this research highlights that cumulative economic losses across the five real-world sites reached 87.95%, exceeding 55,000 MRU. These findings provide a strategic framework for optimizing PV systems in arid terrains and offer a robust tool for enhancing the design and operation of large-scale solar applications in desert environments. Full article

Mercury in jarosites is crucial for environmental management and metallurgy. These minerals can incorporate highly toxic heavy metals from mining waste into their structure. This study analyzes the decomposition of mercury jarosite in a Ca(OH)₂ medium, focusing on its topological, kinetic, and modeling characteristics. Topological analysis, XRD and SEM−EDS were performed. ICP−OES was used to analyze the mercury and sulfur ions diffusing from the mercury jarosite into the Ca(OH)₂ solution. The kinetic model that best fit the data was that of spherical particles of constant size with an unreacted core under chemical control. The XRD results did not show new crystallographic phases. SEM−EDS showed a partially decomposed particle indicating a halo and core. The experimental conditions included temperatures from 298.15 to 333.15 K, concentrations of 0.0071–0.23210 mol L⁻¹ Ca(OH)₂, particle diameters of 25–53 µm, and pH of 11.12–12.85. During the induction period, reaction orders of 1.04 and 0.44 were obtained, along with an activation energy of 77.580 kJ mol⁻¹. For the progressive conversion period, the reaction orders were 0.59 and 0.15, with an activation energy of 52.124 kJ mol⁻¹. The overall kinetic modeling showed favorable results, supporting the evolutionary process of the mercury jarosite decomposition reaction in an alkaline medium under different conditions. This allows prediction of when mercury could be released back into the environment in alkaline soils or lime barriers. Full article

Hopea celebica Burck is an endangered dipterocarp endemic to Sulawesi, Indonesia, occurring in two ecologically contrasting habitats: karst and ultrabasic forests. These environments differ markedly in soil composition and topography, potentially driving ecological specialization and genetic divergence. To investigate the genetic variation and genetic structure of this species, we applied newly developed microsatellite (SSR) markers, together with the chloroplast DNA sequences of the trnL–trnF region. Genotypes at 15 SSR loci were determined for 255 individuals collected from six populations covering the range of the species’ distribution across karst and ultrabasic forests. Genetic diversity was consistently higher in karst than in ultrabasic populations. DIYABC and VarEff analyses revealed a historical bottleneck and earlier recovery in the karst populations. Analysis of molecular variance (AMOVA) revealed that 35% of the genetic variation was partitioned between habitat types (F_RT = 0.345, p = 0.001). Bayesian clustering (STRUCTURE), principal coordinate analysis (PCoA), and UPGMA dendrograms consistently showed two distinctive clusters corresponding to habitat type. Chloroplast haplotypes differed between populations in the karst and ultrabasic forests. These results suggest that populations in the karst and ultrabasic forests have undergone a long history of differentiation without migration. The strong habitat-related genetic structure likely reflects ecological isolation and early-stage speciation. We recommend treating the karst and ultrabasic populations as distinct conservation units to preserve the evolutionary potential and adaptive capacity of H. celebica under ongoing environmental change. Full article

Four areas in the Kongo Central Province, western Democratic Republic of the Congo, with unexploited phosphate deposits were investigated to assess the composition of phosphatic materials and to evaluate pollution hazards, including radiological hazards arising from naturally occurring radionuclides. In those areas, phosphate rocks were sampled and analyzed for P₂O₅ content (by ED-XRF), and for the naturally occurring radionuclides ²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K (by gamma-ray spectrometry). Phosphate rocks displayed P₂O₅ content ranging from 1.06 to 24.42% (dry weight) and exceptionally high ²³⁸U and ²²⁶Ra activity concentrations (up to 3069 and 2273 Bq kg⁻¹, respectively), significantly exceeding global averages in soils. Radiological hazard indices, including the radium equivalent (RaEq), annual effective dose and lifetime cancer risk, confirmed potential health risks associated with phosphate-rich rocks. With the upcoming development of phosphate deposits in DRC, such phosphate materials might become future sources of both geochemical contamination and radiological exposure, emphasizing the need for suitable radiation monitoring and waste management plans prior to and during mineral resource exploitation. Full article

The application of organic residues in agriculture helps to replenish soil organic carbon (OC), improve soil fertility and biodiversity, reinforce aggregate stability, and favour water infiltration. Moreover, its application as a soil amendment alters the fate of herbicides applied to the soil. The objective here was (i) to evaluate soil quality by determining the physicochemical and biological parameters of an agricultural soil (Soil) amended with green compost (Soil + GC) over an arable pea–wheat crop rotation in a short-term experiment; and (ii) to study the dissipation and persistence of iodosulfuron-methyl-sodium applied in field plots sown with winter wheat under real field conditions. The experimental field design consisted of 24 plots (10 m²) involving 12 with control and 12 with GC-amended soils. The plots were sown with pea after GC application (~11 t ha⁻¹) in February 2023, and with winter wheat in October 2023. Iodosulfuron-methyl-sodium (Hussar^® Plus, Bayer CropScience S.L., Barcelona, Spain) was applied in post-emergence at the agronomic dose (D1 = 176 mL ha⁻¹) and double dose (D2 = 352 mL ha⁻¹). Soil samples were taken from the plots to assess the soil physicochemical and biological parameters at six sampling times after GC application, with extraction and determination of residual herbicide and metabolite (metsulfuron-methyl) concentrations. In addition, the yield and characteristics of the pea and wheat grain crops were determined. The application of GC to the soil significantly increased pH (0.5 units by July 2024) and electrical conductivity (up to 5.2 times) compared to control soil, which remained constant throughout the experiment. The OC in Soil + GC increased by 40% in July 2024 compared to control soil. Total nitrogen content increased up to 2.0 and 1.3 times during the pea–wheat growing seasons in Soil + GC compared to unamended soil. Soil dehydrogenase activity, respiration, and biomass increased by up to 1.4, 2.2 and 1.4 times, respectively, in Soil + GC compared to unamended soil over the growing seasons. The soil microbial structure, determined by phospholipid fatty acid (PLFA) analysis, recorded no significant differences between the microbial groups in both soil treatments. A non-significant increase in pea and wheat yield was observed in Soil + GC compared to unamended soil. The results revealed an increase in the residual amounts of herbicide and metabolite, being slightly more persistent, with DT₅₀ and DT₉₀ values up to 1.6 times higher, in the Soil + GC plots over time. Much higher amounts of metabolite (DT₅₀ = 24.8–29.7 days) than iodosulfuron-methyl (DT₅₀ = 5.2–8.8 days) were found in all the treatments. This may be due to wheat plants intercepting the herbicide initially at the time of application in post-emergence, the rapid dissipation of the herbicide reaching the soil, and/or the higher persistence of the metabolite compared to that of the herbicide. Overall, the soil’s physicochemical and biological properties were improved in GC-amended soil, and organic amendment increased slightly the persistence of iodosulfuron-methyl-sodium and its metabolite in the soil. Full article

6PPD-Quinone (6PPD-Q) is a tire derivative formed by the oxidation of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), a commonly used antioxidant and ozone stabilizer in rubber products, and has emerged as a significant environmental concern in recent years. It is widely present in the atmosphere, surface lakes, and soil. The primary routes of exposure to 6PPD-Q are the digestive tract and respiratory tract. Studies indicate that it is a major factor causing acute mortality in coastal coho salmon (Oncorhynchus kisutch). Reports indicate that 6PPD-Q exhibits greater chemical stability and stronger biological toxicity than 6PPD, demonstrating toxic effects across multiple species. 6PPD-Q has been detected in human urine samples, indicating a need for heightened attention to its potential health risks. 6PPD-Q exhibits multi-organ toxicity in organisms, including intestinal, hepatic, neurotoxic, and reproductive toxicity. Its potential toxic mechanisms are associated with oxidative stress and inflammatory responses, and it can disrupt amino acid metabolism, carbohydrate metabolism, and lipid metabolism while interfering with signal transduction pathways by binding to specific receptors. This paper reviews the environmental contamination of 6PPD-Q, explores its potential toxic effects on organisms and underlying mechanisms, analyzes gaps in the current research and future trends, and contributes to a better understanding of its environmental occurrence and biological hazards. Full article