Search Results (336)

Soil organic carbon (SOC) pool plays an extremely important role in regulating the global carbon (C) cycle and climate change. Atmospheric nitrogen (N) and phosphorus (P) deposition caused by human activities has significant impacts on soil C sequestration potential of terrestrial ecosystem. To investigate the effects of N and P deposition on soil C sequestration and C-N coupling relationship in broad-leaved evergreen forests, a 6-year field nutrient regulation experiment was implemented in subtropical Castanopsis sclerophylla forests with four different N and P additions: N addition (100 kg N·hm⁻²·year⁻¹), N + P (100 kg N·hm⁻²·year⁻¹ + 50 kg P·hm⁻²·year⁻¹), P addition (50 kg P·hm⁻²·year⁻¹), and CK (0 kg N·hm⁻²·year⁻¹). The changes in the C and N contents and stable isotope distributions (δ¹³C and δ¹⁵N) of different soil organic fractions were examined. The results showed that the SOC and total nitrogen (STN) (p > 0.05) increased with N addition, while SOC significantly decreased with P addition (p < 0.05), and N + P treatment has low effect on SOC, STN (p > 0.05). By density grouping, it was found that N addition significantly increased light fraction C and N (LFOC, LFN), significantly decreased the light fraction C to N ratio (LFOC/N) (p < 0.05), and increased heavy fraction C and N (HFOC, HFN) accumulation and light fraction to total organic C ratio (LFOC/SOC, p > 0.05). Contrary to N addition, P addition was detrimental to the accumulation of LFOC, LFN and reduced LFOC/SOC. It was found that different reactive oxidized carbon (ROC) increased under N addition but ROC/SOC did not change, while N + P and P treatments increased ROC/SOC, resulting in a decrease in SOC chemical stability. Stable isotope analysis showed that N addition promoted the accumulation of new soil organic matter, whereas P addition enhanced the transformation and utilization of C and N from pre-existing organic matter. Additionally, N addition indirectly increased LFOC by significantly decreasing pH; significantly contributed to LFOC and ROC by increasing STN accumulation promoted by NO₃⁻-N and NH₄⁺-N; and decreased light fraction δ¹³C by significantly increasing dissolved organic C (p < 0.05). P addition had directly significant negative effect on LFOC and SOC (p < 0.05). In conclusion, six-year N deposition enhances soil C and N sequestration while the P enrichment reduces the content of soil C, N fractions and stability in Castanopsis sclerophylla forests. The results provide a scientific basis for predicting the soil C sink function of evergreen broad-leaved forest ecosystem under the background of future climate change. Full article

This work investigates, for the first time, the application of a modified natural magnetite material with 35% of lanthanum for phosphorus (P) recovery from synthetic and actual wastewater under both static (batch) and dynamic (continuous stirred tank reactor (CSTR)) conditions. The characterization results showed that the natural feedstock mainly comprises magnetite and kaolinite. Moreover, the lanthanum-modified magnetite (La-MM) exhibited more enhanced textural, structural, and surface chemistry properties than the natural feedstock. In particular, its surface area (82.7 m² g⁻¹) and total pore volume (0.160 cm³ g⁻¹) were higher by 86.6% and 255.5%, respectively. The La-MM efficiently recovered P in batch mode under diverse experimental settings with an adsorption capacity of 50.7 mg g⁻¹, which is significantly greater than that of various engineered materials. It also maintained high efficiency even when used for the treatment of actual wastewater, with an adsorption capacity of 47.3 mg g⁻¹. In CSTR mode, the amount of P recovered from synthetic solutions and real wastewater decreased to 33.8 and 10.2 mg g⁻¹, respectively, due to the limited contact time. The phosphorus recovery process involves mainly electrostatic attraction over a wide pH interval, complexation, and precipitation as lanthanum phosphates. This investigation indicates that lanthanum-modified natural feedstocks from magnetite deposits can be regarded as promising materials for P recovery from aqueous solutions. Full article

Amid global environmental change, the intensification of nitrogen (N) deposition exerts critical impacts on the growth of forest vegetation and the structure and function of ecosystems in subtropical China. However, the physiological and growth response mechanisms of subtropical tree species remain poorly understood. This study explored adaptive mechanisms of typical subtropical tree species to N deposition, analyzing biomass accumulation, root plasticity, and nutrient/photosynthate allocation strategies. One-year-old potted seedlings of Phyllostachys edulis (moso bamboo) and Cunninghamia lanceolata (Chinese fir) were subjected to four N-addition treatments (N0: 0, N1: 6 g·m⁻²·a⁻¹, N2: 12 g·m⁻²·a⁻¹, N3: 18 g·m⁻²·a⁻¹) for one year. In July and December, measurements were conducted on seedling organ biomass, root morphological and architectural traits, as well as nutrient elements (N and phosphorus(P)) and non-structural carbohydrate (soluble sugars and starch) contents in roots, stems, and leaves. Our results demonstrate that the Chinese fir exhibits stronger tolerance to N deposition and greater root morphological plasticity than moso bamboo. It adapts to N deposition by developing root systems with a higher finer root (diameter ≤ 0.2 mm) ratio, lower construction cost, greater branching intensity and angle, and architecture approaching dichotomous branching. Although N deposition promotes short-term biomass and N accumulation in both species, it reduces P and soluble sugars contents, leading to N/P imbalance and adverse effects on long-term growth. Under conditions of P and photosynthate scarcity, the Chinese fir preferentially allocates soluble sugars to leaves, while moso bamboo prioritizes P and soluble sugars to roots. In the first half of the growing season, moso bamboo allocates more biomass and N to aboveground parts, whereas in the second half, it allocates more biomass and P to roots to adapt to N deposition. This study reveals that Chinese fir enhances its tolerance to N deposition through the plasticity of root morphology and architecture, while moso bamboo exhibits dynamic resource allocation strategies. The research identifies highly adaptive root morphological and architectural patterns, demonstrating that optimizing the allocation of elements and photosynthates and avoiding elemental balance risks represent critical survival mechanisms for subtropical tree species under intensified N deposition. Full article

Rare earth elements (REEs) have garnered significant global attention due to their essential role in advanced technologies. Sri Lanka is endowed with various REE-bearing minerals, including the apatite-rich deposit in the Eppawala area, commonly known as Eppawala rock phosphate (ERP). However, direct extraction of REEs from ERP is technically challenging and economically unfeasible. This study introduces a novel, integrated approach for recovering REEs from ERP as a by-product of nitrophosphate fertilizer production. The process involves nitric acid-based acidolysis of apatite, optimized at 10 M nitric acid for 2 h at 70 °C with a pulp density of 2.4 mL/g. During cooling crystallization, 42 wt% of calcium was removed as Ca(NO₃)₂.4H₂O while REEs remained in the solution. REEs were then selectively precipitated as REE phosphates via pH-controlled addition of ammonium hydroxide, minimizing the co-precipitation with calcium. Further separation was achieved through selective dissolution in a sulfuric–phosphoric acid mixture, followed by precipitation as sodium rare earth double sulfates. The process achieved over 90% total REE recovery with extraction efficiencies in the order of Pr > Nd > Ce > Gd > Sm > Y > Dy. Samples were characterized for their phase composition, elemental content, and morphology. The fertilizer results confirmed the successful production of a nutrient-rich nitrophosphate (NP) with 18.2% nitrogen and 13.9% phosphorus (as P₂O₅) with a low moisture content (0.6%) and minimal free acid (0.1%), indicating strong agronomic value and storage stability. This study represents one of the pioneering efforts to valorize Sri Lanka’s apatite through a novel, dual-purpose, and circular approach, recovering REEs while simultaneously producing high-quality fertilizer. Full article

As part of the work, polymer composites dedicated to rapid prototyping were developed, especially for 3D printing using the material extrusion technique. For this purpose, a polymer matrix was selected, which was an acrylonitrile-butadiene-styrene (ABS) terpolymer and a flame retardant, which was tetrakis (2,6-dimethylphenyl)-m-phenylenebisphosphate, commercially known as PX200. The effect of the presence and amount (5, 10, 15 and 20 wt.%) of the introduced additive on the rheological properties, structural properties, flammability (limiting oxygen index, LOI; UL94) and flame retardant properties (microcone calorimeter, MLC) of ABS-based composites was investigated. In addition, the mechanism of thermal degradation and flame resistance was investigated using thermogravimetric analysis, TGA and Fourier transform infrared spectroscopy, FT-IR of the residue after the MLC test. In the first part of the work, using the author’s technological line, filaments were obtained from unfilled ABS and its composites. Samples for testing were obtained by 3D printing in Fused Deposition Modeling (FDM) technology. In order to determine the quantitative and qualitative spread of fire and the effectiveness of the phosphorus flame retardant PX200 in the produced composites, the Maximum Average Rate of Heat Emission (MARHE); Fire Growth Rate Index (FIGRA); Fire Potential Index (FPI) and Flame Retardancy Index (FRI) were determined. Based on the obtained results, it was found that the aryl biphosphate used in this work exhibits activity in the gas phase, which was confirmed by quantitative assessment using data from a microcone calorimeter and non-residues after combustion and thermolysis at 700 °C. As a result, the flammability class did not change (HB40), and the LOI slightly increased to 20% for the composite with 20% flame retardant content. Moreover, this composite was characterized by the following flammability indices: pHRR = 482.9 kW/m² (−40.3%), MARHE = 234 kW/m² (−40.7%), FIGRA = 3.1 kW/m²·s (−56.3%), FPI = 0.061 m²·s/kW (+64.9%), FRI = 2.068 (+106.8%). Full article

Polyamide 6,6 (PA6,6) fabrics are widely used in textiles due to their high mechanical strength and chemical stability. However, their inherent flammability and melting behavior under fire pose significant safety challenges. In this study, a dual-layer flame-retardant system was developed by integrating atomic layer deposition (ALD) of ZnO with a phosphorus–silane-based flame retardant (DOPO-ETES). ALD allowed precise control of ZnO layer thickness (50, 84, and 199 nm), ensuring uniform coating. Thermal analysis (TGA) and microscale combustion calorimetry (MCC) revealed that ZnO altered the degradation pathway of PA6,6 through catalytic effects, promoting char formation and reducing heat release. The combination of ZnO and DOPO-ETES resulted in further reductions in heat release rates. However, direct flame tests showed that self-extinguishing behavior was not achieved, emphasizing the limitations related to the melting of PA6,6. TG-IR and cone calorimetry confirmed that ZnO coatings suppressed the release of smoke-related volatiles and incomplete combustion products. These findings highlight the potential of combining metal-based catalytic flame retardants like ZnO with phosphorus-based coatings to improve flame retardancy while addressing the specific challenges of polyamide textiles. This approach may also be adapted to other fabric types and integrated with additional flame retardants, broadening its relevance for textile applications. Full article

In the context of China’s ecosystem facing a high intensity of nitrogen loads, carbon–nitrogen interactions are receiving increasing attention. Physical protection by soil aggregates is critical for soil carbon and nitrogen sequestration in terrestrial ecosystems; however, there is currently limited information on how nitrogen addition influences carbon and nitrogen dynamics across different stages of forest ageing. Herein, a field nitrogen manipulation experiment over 6 years was established in subtropical forests (46, 78, and about 200 years old) in China. Aggregate fractions and stable isotope analyses were used to assess the effects of nitrogen addition. The results show that forest soil was dominated by macroaggregates, and these increased with forest ageing (p > 0.05). The macroaggregates’ carbon content decreased with forest ageing (p > 0.05), while the macroaggregates’ nitrogen content was highest in the 200-year-old forest. Nitrogen addition increased the aggregates’ carbon and nitrogen concentrations in the 46- and 200-year-old forests. The macroaggregates, under nitrogen addition in the 78- and 200-year-old forests, were relatively weak, while forest age and nitrogen addition mainly affected macroaggregate carbon and nitrogen concentrations to promote their carbon and nitrogen storage, and the macroaggregates were the main storage unit for fixing and protecting new carbon in soils. Nitrogen addition increased the macroaggregates’ δ¹³C abundance in the 78- and 200-year-old forests and decreased it in the 46-year-old forest (p > 0.05); significantly increased the macroaggregates’ δ¹⁵N in the 46-year-old forest (p < 0.05), and decreased the macroaggregates’ δ¹⁵N in the 200-year-old forest (p > 0.05). Considering the distribution of δ¹³C and δ¹⁵N in the aggregates, the effect of nitrogen addition on the dynamic mechanism of soil aggregate carbon and nitrogen fractions varied based on forest age and aggregate size. Correlation analysis further revealed that soil total phosphorus, NH₄⁺-N, NO₃⁻-N, dissolved organic nitrogen, pH, texture, etc., were the primary predictors explaining most of the variation in aggregate fractions and their δ¹³C distribution. In summary, the effect of nitrogen deposition on the carbon and nitrogen stability of soil aggregates in broad-leaved forests depends on forest age. Full article

Forest fires critically disrupt soil ecosystems by altering physicochemical properties and microbial structure-function dynamics. This study assessed short-term impacts of fire intensities (light/moderate/heavy) on microbial communities in Larix gmelinii forests one year post-fire. Using phospholipid fatty acid (PLFA) and Biolog EcoPlate analyses, we found the following: (1) fire reduced soil organic carbon (SOC), dissolved organic carbon (DOC), total nitrogen (TN), and available nitrogen/potassium (AN/AK) via pyrolytic carbon release, while heavy-intensity fires enriched available phosphorus (AP), AN, and AK through ash deposition. (2) Thermal mortality and nutrient-pH-moisture stress persistently suppressed microbial biomass and metabolic activity. Moderate fires increased taxonomic richness but reduced functional diversity, confirming “functional redundancy.” (3) Neither soil microbial biomass nor metabolic activity at the fire site reached pre-fire levels after one year of recovery. Our findings advance post-fire soil restoration frameworks and advocate multi-omics integration to decode fire-adapted functional gene networks, guiding climate-resilient forest management. Full article

This study quantifies the atmospheric deposition (AD) of nutrient loads into the Farmington Bay ecosystem via wet deposition over a three-year period. We analyzed nutrient concentrations from 509 total phosphorus (TP), 507 orthophosphate (OP), and 511 total nitrogen (TN) samples collected at seven locations around the Bay. We estimated AD loads using two different spatial interpolation methods, Kriging and Inverse Distance Weighting (IDW), as well as average concentrations. The loads computed using Kriging and IDW were similar, but the loads computed using sample averages were about 70% smaller. We estimated that annual atmospherically deposited nutrient loads range from 306 to 594 Mg for TN, 73 to 195 Mg for TP, and 43 to 144 Mg for OP. The loads in 2023 were significantly higher than those in 2021 and 2022, a phenomenon we attribute to higher precipitation and a major loading event that occurred on 13 April 2023. Based on comparison with studies concerning nearby Utah Lake, the total loads could be two to three times larger than our estimates. These studies suggest that fine particulate matter may significantly contribute to AD nutrient loads, but these loads are not captured by our sampling method. However, the inclusion of non-water surfaces in Farmington Bay may mitigate this difference. Full article

Prior to the laser processing, the surface of the TiC-reinforced particles underwent a metallization process with Ni-P, with the objective of enhancing the wettability between the TiC and the Ti6Al4V, thereby ensuring enhanced wear resistance of the titanium-based composite (TMC) coatings. In this study, the chemical deposition method was utilized to synthesize three types of metallized TiC with varying phosphorus contents. The P contents of these samples were determined to be 9.12 wt.% (HP metallized TiC), 6.55 wt.% (MP metallized TiC), and 1.71 wt.% (LP metallized TiC). It was observed that the thickness of the coatings increased in a gradual manner with the decrease in P. Furthermore, the coating of the LP metallized TiC was found to possess the highest degree of crystallinity and a microcrystalline structure. The 50 wt.% TiC-Ti6Al4V composite coatings (TMC-Nickel-free, TMC-HP, TMC-MP, and TMC-LP) were produced by laser fusion deposition using untreated TiC and three metallized TiC enhancements. The findings indicate that TMC-LP exhibits cracking only during the initial processing stage. Surface metallization has been shown to enhance the wear resistance of composite coatings through several mechanisms, including increased bonding of the ceramic phase to the metal matrix and the formation of hard Ti₂Ni compounds. The wear rates of TMC-HP, TMC-MP, and TMC-LP were reduced by 22%, 43%, and 72%, respectively, in comparison to TMC-Nickel-free. Full article

Tropical cyclones can severely disturb shallow, continental shelf ecosystems, affecting habitat structure, diversity, and ecosystem services. This study examines the impacts of Hurricane Ian on the Southwest Florida Shelf by assessing water quality, substrate type, and epibenthic and microbial community characteristics at eight sites (3 to 20 m in depth) before and after Ian’s passage in 2022. Hurricane Ian drastically changed substrate type and biotic cover, scouring away epibenthos and/or burying hard substrates in mud and sand, especially at mid depth (10 m) sites (92–98% loss). Following Hurricane Ian, the greatest losses were observed in fleshy macroalgae (58%), calcareous green algae (100%), seagrass (100%), sessile invertebrates (77%), and stony coral communities (71%), while soft coral (17%) and sponge communities (45%) were more resistant. After Ian, turbidity, chromophoric dissolved organic matter, and dissolved inorganic nitrogen and phosphorus increased at most sites, while total nitrogen, total phosphorus, and silica decreased. Microbial communities changed significantly post Ian, with estuary-associated taxa expanding further offshore. The results show that the shelf ecosystem is highly susceptible to disturbances from waves, deposition and erosion, and water quality changes caused by mixing and coastal discharge. More routine monitoring of this environment is necessary to understand the long-term patterns of these disturbances, their interactions, and how they influence the resilience and recovery processes of shelf ecosystems. Full article

This work deals with the effects of a non-electrochemically deposited copper- or nickel–phosphorus-based coating on the resulting resistance of traditional X42 grade pipeline steel against hydrogen embrittlement (HE). The susceptibility to HE was determined by the evaluation of the hydrogen embrittlement index (HEI) from the results of conventional room-temperature tensile tests using cylindrical tensile specimens. Altogether, three individual material systems were studied, namely uncoated steel (X42) and two coated steels, specifically with either a copper-based coating (X42_Cu) or a nickel–phosphorus-based coating (X42_Ni-P). The HEI values were calculated as relative changes in individual mechanical properties corresponding to the non-hydrogenated and electrochemically hydrogen-precharged tensile test conditions. Both applied coatings considerably improved the hydrogen embrittlement resistance of the investigated steel in terms of decreasing the HEI values related to the changes in the yield stress, ultimate tensile strength, and reduction of area. In contrast, the hydrogenation of both coated systems had detrimental effects on the value of total elongation, which resulted in an increase in the corresponding HEI value. This behavior was likely related to the earlier onset of necking during tensile straining due to strain localizations induced by the coatings’ surface imperfections. The findings from fractographic observations indicated that both studied coatings acted like protective barriers against hydrogen permeation. However, the surface quality in terms of pores and other superficial defects in the considered coatings remains a challenging issue. Full article

In this research work, a natural sample from an Omani magnetite (MG) deposit was used for the synthesis of a magnetite decorated with ferrihydrite (MG-Fh), and two lanthanum (La)-modified materials at mass percentages of 5% (MG-Fh-La-5) and 15% (MG-Fh-La-15). These materials were first characterized using various analytical techniques. Then, their phosphorus (P) recovery efficacy from aqueous solutions was studied in batch mode under a wide range of experimental conditions. The characterization results show that compared to the raw feedstock, MG-Fh, MG-Fh-La-5, and especially MG-Fh-La-15 have improved structural, textural, and surface chemistry properties. Adsorption tests indicate that due to the deposition of high contents of lanthanum oxides on its surface, the MG-La-15 exhibited a large P uptake capacity (34.5 mg g⁻¹), which is significantly superior to those determined for MG-La-5 (24.3 mg g⁻¹), MG-Fh (12.4 mg g⁻¹), and various engineered materials published in the literature. Moreover, these materials retain an interesting ability to recover P from real wastewater with a highest adsorbed mass of 27.3 mg g⁻¹, observed for MG-La-15. The P recovery seems to involve both physical and chemical mechanisms, including electrostatic interactions and complexation. This research work shows that La-modified magnetite can be considered a promising and eco-friendly material for P recovery from liquid effluents. Full article

Phosphorus (P) excess in the aquatic environment is a source of eutrophication leading to the deterioration of water quality and biodiversity loss. Methods of in situ controlling P in lakes and reservoirs mostly require the addition of chemical substances to a water body without the possibility of controlling their future interactions with the environment. This study compared the performance of two solutions, laminates and modules, developed for non-invasive P removal from aquatic ecosystems with the use of calcite mineral as a P-reactive material. Both techniques enable reductions in the orthophosphate (OP) availability in lake water, and its removal from the ecosystem, without the permanent deposition of the P binding agent in the environment. In a laboratory mesocosm experiment, both, laminates and modules, lowered the OP concentration in lake water for at least 6 weeks compared to no treatment; the efficiency of modules was, however, much higher. They effectively eliminated the OP initially available in the system and further captured the OP newly supplied by the decomposition processes, showing continuous OP uptake, while laminates appeared to exhaust their capacity after about 1 week. This was mostly because of technical design—the calcite dose per m² of the surface area was 168 times higher in modules compared to laminates. Treatment using both techniques caused a slight pH decrease compared to no treatment with a minor change of up to 0.2 point. Modules have the most potential for the implementation in practice as they are able to decrease the OP concentration for relatively long time periods of weeks to months without the need to be exchanged. They offer a refillable and reusable system for P control, removal, and recovery. Field tests should be performed to verify the performance of modules and laminates under in-lake conditions and complex interactions with the aquatic organisms to check for possible limitations and/or synergies between the non-invasive P removal techniques and native processes. Full article

Phosphorus is one of the most abundant minerals in the body and plays a critical role in numerous cellular and metabolic processes. Most of the phosphate is deposited in bones, 14% is present in soft tissues as various organic phosphates, and only 1% is found in extracellular space, mainly as inorganic phosphate. The plasma inorganic phosphate concentration is closely maintained between 2.5 and 4.5 mg/dL by intertwined interactions between fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), and vitamin D, which tightly regulate the phosphate trafficking across the gastrointestinal tract, kidneys, and bones. Disruption of the strict hemostatic control of phosphate balance can lead to altered cellular and organ functions that are associated with high morbidity and mortality. In the past three decades, there has been a steady increase in the prevalence of kidney failure (KF) among populations. Individuals with KF have unacceptably high mortality, and well over half of deaths are related to cardiovascular disease. Abnormal phosphate metabolism is one of the major factors that is independently associated with vascular calcification and cardiovascular mortality in KF. In early stages of CKD, adaptive processes involving FGF-23, PTH, and vitamin D occur in response to dietary phosphate load to maintain plasma phosphate level in the normal range. However, as the CKD progresses, these adaptive events are unable to overcome phosphate retention from continued dietary phosphate intake and overt hyperphosphatemia ensues. As these hormonal imbalances and the associated adverse consequences are driven by the underlying hyperphosphatemic state in KF, it appears logical to strictly control serum phosphate. Conventional dialysis is inadequate in removing phosphate and most patients require dietary restrictions and pharmacologic interventions to manage hyperphosphatemia. However, diet control comes with many challenges with adherence and may place patients at risk for inadequate protein intake and malnutrition. Phosphate binders help to reduce phosphate levels but come with a sizable pill burden and high financial costs and are associated with poor adherence and psychosocial issues. Additionally, long-term use of binders may increase the risk of calcium, lanthanum, or iron overload or promote gastrointestinal side effects that exacerbate malnutrition and affect quality of life. Given the aforesaid challenges with phosphorus binders, novel therapies targeting small intestinal phosphate absorption pathways have been investigated. Recently, tenapanor, an agent that blocks paracellular absorption of phosphate via inhibition of enteric sodium–hydrogen exchanger-3 (NHE3) was approved for the treatment of hyperphosphatemia in KF. While various clinical tools are now available to manage hyperphosphatemia, there is a lack of convincing clinical data to demonstrate improvement in outcomes in KF with the lowering of phosphorus level. Conceivably, deleterious effects associated with hyperphosphatemia could be attributable to disruptions in phosphorus-sensing mechanisms and hormonal imbalance thereof. Further exploration of mechanisms that precisely control phosphorus sensing and regulation may facilitate development of strategies to diminish the deleterious effects of phosphorus load and improve overall outcomes in KF. Full article