Distribution Of Phosphorus Research Articles

PagSND1-B1 Regulates Wood Formation by Influencing Phosphorus Absorption and Distribution in Poplar.

In natural environments, the growth and development of trees are continuously affected by phosphorus (P) starvation stress. However, the mechanisms through which trees balance stem growth and P distribution remain unknown. This study found that in the woody model species poplar, the P loss in stems is more severe than that in roots and leaves under P starvation conditions, thereby inhibiting stem development and reducing the expression of numerous genes related to wood formation, including PagSND1-B1. Intriguingly, overexpression of PagSND1-B1 in poplar enhances resistance to P starvation and promotes xylem development. Further analysis demonstrated that PagSND1-B1 can directly and positively regulate the phosphorus transporter PagPHT1;5a. Analysis of P content changes in leaves, stems and roots of transgenic poplar before and after treatment indicated that overexpression of PagSND1-B1 disrupts the normal P redistribution procedure, leading to increased P accumulation in stems, which is beneficial for xylem development. Therefore, PagSND1-B1 participates in the phosphorus absorption and homoeostasis of poplar by modulating PagPHT1;5a. This study provides valuable insights into the regulatory function of PagSND1-B1 in wood formation and the process by which trees balance phosphorus distribution and xylem development.

Genome-Wide Analysis, Identification, and Transcriptional Profile of the Response to Abiotic Stress of the Purple Acid Phosphatases (PAP) Gene Family in Apple

Purple acid phosphatases (PAPs) play a significant role in plant phosphorus nutrition and can not only release phosphorus from the soil but also regulate the distribution of phosphorus in plants throughout their entire growth and development process. Moreover, members of the PAP protein family exert a more extensive influence on plant mineral homeostasis, developmental processes, and stress responses. Three clusters of purple acid phosphatases, including 31 putative genes, were identified in apples (Malus domestica) by searching the Genome Database for Rosaceae. The structure, chromosomal distribution and location, phylogeny, motifs, and cis-acting elements in the gene promoter regions of the MdPAP gene family are reviewed. These genes exhibit different expression patterns in different tissues. For example, almost all MdPAP genes are strongly expressed in the roots, except for MdPAP10, MdPAP12, and MdPAP27. Similarily, all MdPAPs were expressed in the leaves while the transcript levels of MdPAP7, MdPAP10, MdPAP15, MdPAP21, MdPAP24, MdPAP26, MdPAP29, and MdPAP30 were highest in apple flowers. Overall, the expression of the 31 genes significantly changed in either the roots or leaves following the application of phosphorus and/or drought stress. These results indicate that MdPAP family members play a role in plant adaptation to adverse environments. This work explores the adaptative responses to phosphorus and/or drought conditions in apple and establishes a foundation for an enhanced comprehension of the evolution of PAP families and the exploration of the genes of interest.

Evaluating soils phosphorus forms and distribution under different land use types

Abstract. Following nitrogen (N), phosphorus (P) is the second most important macronutrient for plant and microorganism development. Phosphorus is found in nucleic acids, phospholipids, and ATP and is required for energy transmission and cell structure. Phosphorus is also essential for biomass accumulation and primary productivity. However, it is often present in low availability forms in the extensively worn soils of tropical and subtropical regions, which has been considered one of the key limiting factors for agricultural output. Hence, the reason for this research being carried out. A total of 24 soil samples were collected from four different land uses at depths 0-15 cm and 15-30 cm, respectively, within the Kogi State University area of Anyigba with the aim of evaluating the effects of land on forms and distributions of phosphorus. The study was a 4 × 3 × 2 factorial experiment laid out in a Randomized Complete Block Design. Available P, total organic P, total inorganic P, inorganic P fractions (Fe-P, Ca-P, Al-P, Red-P and Occ/Fe-Al-P) analyses were carried out using standard procedures. The data from the laboratory analyses were subjected to three-way analysis of variance, and the means between treatments were separated using Tukey's test with a 5 % probability. The results revealed that the soils contained low levels of available P. The soil beneath forest land had the highest available P concentration (10.92 mg/kg), whereas the lowest was found in cultivated land (8.97 mg/kg). The P forms declined with depths. According to the findings, Fe-P had the highest amounts of inorganic P fractions in the research area. Lower P concentrations in cultivated land were related to lower organic matter content caused by continuous crops cultivation on the soil. Phosphorus fractions investigations are thus advised in cultivated soils to provide an adequate understanding of P status in the soil and fertilizer recommendations to boost productivity.

Effects of Biochar and Organic Acid Addition on Phosphorus State and Yield of Cotton Field Under Different Phosphate Fertilizer Application Rates

The purpose of this study is to investigate the effect of biochar and organic acid on soil phosphorus effectiveness, plant accumulation phosphorus absorption, yield composition, and phosphorus equilibrium under different phosphorus fertilizer dosage conditions. Using the field test method, different phosphate fertilizer dosage treatments (0, 50, 100, 150 kg P2O5/ha) were set, and a control group, biochar (BC), and organic acid (OA) addition treatment were set up on this basis. During the experiment, the soil fast-acting phosphorus, accumulated phosphorus absorption, and cottonseed yield of cotton were measured, and the utilization of phosphorus fertilizer and phosphorus surplus were calculated. The results showed that the addition of biochar and organic acid significantly improved the soil phosphorus content, plant accumulation phosphorus absorption, cottonseed yield, and phosphate fertilizer utilization. In particular, in terms of plant accumulation of phosphorus absorption, cottonseed production and phosphate fertilizer utilization, biochar was better than organic acids, increasing by 10.2%, 0.29%, and 0.21%, respectively. Under the conditions of phosphorus fertilizer loss, the addition of biochar can effectively improve the effectiveness of phosphorus in soil and regulate the absorption and distribution of phosphorus in cotton, thus promoting the yield of cottonseed. In summary, the addition of biochar has important application potential in phosphorus management in cotton fields, which can provide a scientific basis for the sustainable development of cotton fields in Xinjiang. The results provide a reference for the rational use and management of phosphate fertilizer in cotton fields and promote the sustainable development of agriculture.

Phosphorus and cadmium release and distribution characteristics in environmental microinterfaces of biochar based on DGT technology

ABSTRACT This study employs a soil-biochar-soil sandwich model to investigate phosphorus and cadmium transport mechanisms at the biochar-soil interface. Utilizing DGT-CID technology, we found phosphorus and cadmium exhibit gradient diffusion, with biochar as the diffusion center. Biochar significantly increased soil effective phosphorus concentration by 7-fold (p < 0.05) through sustained release. Cadmium concentration increased from 7.11 mg/L to 10.09 mg/L, with a concentration jump at the interface, indicating aggregation and transfer towards the biochar layer. Theoretical calculations show that the transport fluxes of phosphorus and cadmium at the interface were 0.94 mg/L and 0.75 mg/L, respectively. Our findings clarify the distribution and transport fluxes of these elements at the biochar-soil interface.

Selective non-radical Co(IV)=O formation via precise nitrogen coordination of high-spin cobalt atoms

High-valent metal oxides (HVMOs) exhibited strong selective oxidation capabilities for organic contaminants in advanced oxidation processes (AOPs). However, their production was often limited by the strong binding of oxygen ligands to metals in high valence states. In this investigation, we fabricated a nitrogen-enriched CoMnP catalyst through the heteroatom doping of transition metal phosphides (TMPs), effectively boosting the production of HVMOs and exhibiting robust activation of peroxymonosulfate (PMS) for the breakdown of triadimefon (TDF). The Co(IV)=O was pinpointed as the key reactive oxygen species (ROS) driving the degradation of TDF. And the introduction of nitrogen was establishing a localized polar electric field along the P → Co → N axis, leaded to electron withdrawal near the Co-P bond, improving Co electron delocalization weakened by dispersed phosphorus distribution. Such enhanced delocalization increased the likelihood of Co(IV)=O formation through the loss of double electrons by Co, consistent with the coupled electron–proton transfer (CEPT) mechanism. This research introduced an innovative approach to the targeted development of potent catalysts for the production of HVMOs.

Distribution of phosphorus forms in soil amended with poultry litter of different ages and application rates: Agronomic and environmental perspectives

AbstractPoultry litter (PL) can be used as a viable alternative to phosphate fertilizers. However, there is a lack of information about phosphorus (P) distribution in inorganic (Pi) and organic (Po) forms and its transformation in soils amended with PL of varying age (based on litter clean‐out frequency) and application rate. This study aimed to determine the effect of PL age and application rate on soil P forms and their bioavailability. Soils were amended with 5 and 10 Mg ha−1 PL using 6‐, 18‐, and 30‐month‐old litter and incubated for 6 months. Soil P fractionation was performed following the Hedley protocol. Soil P availability and soil P storage capacity (SPSC) were determined using Mehlich 3 (M3) extraction. Results indicated that P transformation from labile to stable P forms occurred over 150‐day incubation. Litter age had no significant effect on the distribution of soil P forms. However, the highly reactive Pi (HRPi) form was higher for treatments with 10 Mg ha−1 PL on Day 0, indicating a risk for P loss, which was also revealed by negative SPSC for those treatments. At Day 0, M3‐P was positively correlated to HRPi. However, from Day 30 to 150, M3‐P was strongly correlated to both HRPi and moderately reactive Pi (MRPi) forms, indicating MRPi contribution to soil P availability. The negative relationship between HRPi and SPSC further confirms that high HRPi on Day 0 may be an environmental concern.

Redistribution of phosphorus fraction driven by organic carbon and microbial community during composting

Available information on the coupling relationship between phosphorus fraction and organic carbon during composting remains limited. Thus, this research investigated the changes of phosphorus fraction, dissolved organic carbon fluorescent components and microbial community in swine manure composting with different carbon sources including the maize straw (MS), garden waste (GW) and distillers’ grains (DG), in order to investigate whether the distribution and availability of phosphorus are influenced by different carbon sources used in the composting of swine manure. The result showed that different carbon sources changed phosphorus availability variously mainly by altering the succession of fungal communities and phosphorus functional genes. The dissolved organic material including tyrosine and tryptophan facilitate the mineralization of organic phosphorus (Org-P) into water-soluble phosphorus, thereby improving phosphorus availability. However, humic acid-like carbon components promote the conversion of inorganic-phosphorus to Org-P, which is the direct cause of the reduced phosphorus availability during composting. The results of this study provide support for the development of phosphorus-rich, stable, and clean compost products.

Evaluation of gridded cropland phosphorus budget and use efficiency in China

Changes in soil phosphorus (P) distribution and budget critically impact the sustainability of agricultural systems. Yet, few studies have examined the long-term evolution of cropland (and crop-specific) P budget and use efficiency (PUE) at a grid level. Here, we conducted a comprehensive evaluation of the cropland P budget and PUE and their human-environmental drivers in China during 1992–2018 at a spatial resolution of 0.1°. The results reveal a significant shift in China's cropland P budget from a deficit of −3.70 Tg P yr−1 in 1992 to a surplus of 0.31 Tg P yr−1 in 2018, mainly driven by increased fertilizer application and decreased soil erosion by water. The concurrent national average cropland PUE initially decreased from 0.51 in 1992 to 0.34 in 2003, but afterwards increased to 0.39 in 2015. An environmental-Kuznets-curve-like (EKC) relationship was identified between the national average P budget (inverted U-shaped) or PUE (U-shaped) and per capita GDP in China, with the turning point occurring in 2013 for the previous and at per capita GDP of US$8.85 k (constant 2017 US$) for the latter. But PUE had been well below a threshold of 0.40 at the national level after crossing the turning point and showed a considerable trend divergence among crops, particularly for cash ones. Spatially, northern and northwestern China exhibited high positive P budget but achieved relatively low PUE in the 2010s. Crop leaf area, irrigation, fertilizer input, and precipitation were identified as the most important factors determining the multi-year spatial pattern of P budget, while fertilizer input, temperature, and residue return played a dominant role in regulating PUE. Our findings highlight the need for a long-term commitment to regionalized and crop-specific synthetic management practices for controlling P inputs and minimizing P loss in the context of global change in China.

Neodymium-Facilitated Visualization of Extreme Phosphate Accumulation in Fibroblast Filopodia: Implications for Intercellular and Cell–Matrix Interactions

A comprehensive understanding of intercellular and cell–matrix interactions is essential for advancing our knowledge of cell biology. Existing techniques, such as fluorescence microscopy and electron microscopy, face limitations in resolution and sample preparation. Supravital lanthanoid staining provides new opportunities for detailed visualization of cellular metabolism and intercellular interactions. This study aims to describe the structure, elemental chemical, and probable origin of zones of extreme lanthanoid (neodymium) accumulation that form during preparation for scanning electron microscopy (SEM) analysis in corneal fibroblasts filopodia. The results identified three morphological patterns of neodymium staining in fibroblast filopodia, each exhibiting asymmetric staining within a thin, sharp, and extremely bright barrier zone, located perpendicular to the filopodia axis. Semi-quantitative chemical analyses showed neodymium-labeled non-linear phosphorus distribution within filopodia, potentially indicating varying phosphate anion concentrations and extreme phosphate accumulation at a physical or physicochemical barrier. Phosphorus zones labeled with neodymium did not correspond to mitochondrial clusters. During apoptosis, the number of filopodia with extreme and asymmetric phosphorus accumulation increases. Supravital lanthanoid staining coupled with SEM allows detailed visualization of intercellular and cell–matrix interactions with high contrast and resolution. These results enhance our understanding of phosphate anion accumulation and transfer mechanisms in cells under normal conditions and during apoptosis.

Distribution of Subsurface Nitrogen and Phosphorus from Different Irrigation Methods in a Maize Field

With the advancement of agricultural technology, most crop cultivation adopts water-saving techniques to improve nutrient utilization efficiency. However, limited research has been carried out on the applicability of water-saving techniques for summer maize in the Shandong Province, and it is necessary to assess the risk of nutrient loss in farmland when applying these technologies. This study investigated the distribution of nitrogen and phosphorus under different irrigation methods and planting patterns through soil and water samples. It included sprinkler irrigation (SI), drip irrigation (DI), and subsurface irrigation (SUBI). Different planting patterns, i.e., monoculture (MP) and intercropping pattern (IP), were also selected in the SI zones. The results show variations in soil nitrogen distribution within the layers between 0.9 and 4.5 m, with a pronounced trend of NO3−-N accumulating in deeper layers in the SI zone. Under SI conditions, the IP effectively reduces the nutrient accumulation around the shallow root zone while controlling the accumulation of nitrogen in deep layers. The Olsen-P accumulation in each zone would increase after the accumulation ratio decreased. Compared with MP, the depth interval of the accumulation ratio mutation was shallower in the IP. The trend of NO3−-N accumulation in deep layers is consistent with that of nitrogen concentration in groundwater. Phosphorus that is accumulated in the deep layers is not easily leached into groundwater. In conclusion, these findings can provide basic information for irrigation management in existing cropping systems.

Contribution of mycorrhizal symbiosis and root strategy to red clover aboveground biomass under nitrogen addition and phosphorus distribution.

Soil nutrients exhibit heterogeneity in their spatial distribution, presenting challenges to plant acquisition. Notably, phosphorus (P) heterogeneity is a characteristic feature of soil, necessitating the development of adaptive strategies by plants to cope with this phenomenon. To address this, fully crossed three-factor experiments were conducted using red clover within rhizoboxes. Positions of P in three conditions, included P even distribution (even P), P close distribution (close P), and P far distribution (far P). Concurrently, N addition was two amounts(0 and 20mg kg- 1), both with and without AMF inoculation. The findings indicated a decrease in aboveground biomass attributable to uneven P distribution, whereas N and AMF demonstrated the potential to affect aboveground biomass. In a structural equation model, AMF primarily increased aboveground biomass by enhancing nodule number and specific leaf area (SLA). In contrast, N addition improved aboveground biomass through increased nodule number or direct effects. Subsequently, a random forest model indicated that under the far P treatment, fine root length emerged as the primary factor affecting aboveground biomass, followed by thickest root length. Conversely, in the even P treatment, the thickest root length was of paramount importance. In summary, when confronted with uneven P distribution, clover plants adopted various root foraging strategies. AMF played a pivotal role in elevating nodule number, and SLA.

Phosphorus dynamics in volcanic soils of Weizhou Island, China: implications for environmental and agricultural applications

The dynamics of phosphorus are intricately governed by geological and ecological processes. Examining phosphorus dynamics in volcanic islands can enhance our comprehension of its behavior within such unique geological systems. However, research on phosphorus dynamics in volcanic islands remains limited. We investigated the phosphorus content of volcaniclastic rocks and basalt soils from Weizhou Island, China, to understand the influencing factors on phosphorus dynamics. The results indicate that in the volcaniclastic profile, phosphorus concentrates at 20–40 cm (17 mg/kg), decreases at 40–60 cm (11.9 mg/kg), and increases at 80–200 cm up to 46.4 mg/kg proximate to the bedrock, for the basalt profile, phosphorus content increases from the surface (80.2 mg/kg) towards the bedrock (83.9 mg/kg). The differences in phosphorus distribution between volcaniclastic rocks and basalts reflect the influence of parent material, rock weathering degree, carbonate content, topographic elevation, sea level changes, and geological activities. A strong positive correlation (R = 0.96907) between total and available phosphorus has been observed, suggesting that total phosphorus content effectively predicts available phosphorus content. Volcaniclastic rocks in wharves and high-elevation areas show low total phosphorus, while forest land with dense vegetation and neutral to alkaline soil supports higher total phosphorus due to enhanced bioavailability for plant absorption and utilization. Overall, the basalt soil of the volcanic island Weizhou Island demonstrates superior long-term fertility compared to the volcaniclastic soil. Despite its low total phosphorus content, it mainly exists in a highly bioavailable form, facilitating plant absorption, which is crucial for enhancing agricultural yields and ecosystem restoration on volcanic islands.

In-Situ Investigation of Phosphorus Transformation and Distribution During Gas-Based Reduction of High-Phosphorus Oolitic Hematite

In-Situ Investigation of Phosphorus Transformation and Distribution During Gas-Based Reduction of High-Phosphorus Oolitic Hematite

Spatial distribution of available phosphorus in surface road and trackway surface materials on a sheep farm in Ireland

Farm roadway runoff is a high-risk source of pollution when connectivity with waters occurs. Nutrients in this runoff are dominated by fresh animal deposits, but recent dairy and beef farm studies showed that available phosphorus (P) accumulates in roadway surface material and can be lost in runoff. A current knowledge gap is to examine available P concentrations in unsealed roadway and trackway (non-maintained) network of a lowland sheep farm. The present study focused on a 45 ha farm stocked with 544 sheep in south-east Ireland. Ten locations were sampled along with the adjacent fields for available P (i.e., Morgan’s P) and ancillary parameters (e.g., pH, total P and heavy metals) in December 2022. The first sampling location was on an aggregate roadway and the other nine were on trackways representing an older aggregate roadway network used by the flock but now covered with soil and grass. Results showed a distinct difference in surface material pH between roadway and trackway locations. Trackways had a pH that mimicked adjacent fields around the agronomic optimum for grassland of ∼6.2. All sampling locations had elevated available P concentrations, ranging from 26.3 to 111.0 mg L−1 (mean 62.8 mg L−1), similar to the spatial distribution for dairy farms but above those found at beef farms previously studied. The highest available P concentrations were found in roadway and trackway sections adjacent to the farmyard. Other elevated sampling areas were on trackways (87.3 or 97.7 mg P L−1) away from the farmyard where sheep are funnelled to pasture, stop to seek shade, urinate and defecate but do not graze. By contrast the average available P concentration for the surrounding fields was 8.4 mg L−1 with a range of 2.7–15.9 mg L−1. Two sampling areas combine to create a critical source area where a high available P source becomes visibly mobilised as runoff during rainfall, discharges into an open drainage ditch, which is then connected to a local stream. Breaking the pathway before runoff enters the open ditch could be a cheap and effective way of mitigating nutrient losses at these two locations.

Elevated effect of hydrothermal treatment on phosphorus transition between solid-liquid phase in swine manure

The morphology and composition of phosphorus in biomass wastes are key factors in determining its potential for utilization. However, the morphological distribution and evolutionary mechanism of phosphorus during the hydrothermal conversion of biomass wastes are still unclear. In this study, swine manure was investigated as the research subject, and the changes in its solid-phase organic components, such as lignocellulose, and inorganic constituents, including metals and phosphorus, during the hydrothermal carbonization (HTC) processes were analyzed in relation to hydrothermal reaction severity (LnR0). A significant linear correlation in Phase II was observed between the solid-phase yield of swine manure and the LnR0. The rapid decline in the solid-phase yield during the initial phase (LnR0 < 9.72) was primarily attributed to the hydrolysis of hemicellulose and similar components. Similarly, solid phase phosphorus showed a very significant phase II with the decrease of solid phase yield. In the first stage, inorganic phosphorus and metal ions (calcium ions, magnesium ions) transferred to the liquid phase (LnR0<9.41). When LnR0 > 9.41, and the driving force of inorganic phosphorus and metal ions into solid phase is enhanced. As the LnR0 was further increased, the HTC could fix over 90 % of the total phosphorus content. XANES analysis indicated that hydroxyapatite emerged as the predominant phosphorus fraction in the solid-phase products, comprising more than 60 %, while magnesium ammonium phosphate components also appeared. This research elucidates the underlying mechanisms of component interaction and phosphorus transformation, providing a solid foundation for enhancing the reuse efficiency of phosphorus in wastes.

Phosphorus distributions in alluvial soils of the Lower Mississippi River Basin: A case of dual legacies.

Legacies can become intertwined, none more so than the body of work of Dr. Andrew Sharpley examining agricultural nutrient delivery to waterbodies and the phosphorus (P) accumulation in agricultural soils, or "legacy P." Although Sharpley's work focused on the anthropogenic influence on soil P, our study suggests soils of the Lower Mississippi Alluvial Plain (MAP) represent a natural legacy with moderate levels of available P resulting from minimal anthropogenic input. In 2019, we collected surface (0-5cm) soil samples from four regionally dominant soil series in either cropland or forested land uses, spanning 76 locations within the MAP. Soil chemical and physical properties were measured utilizing a suite of extractions and texture analysis to correlate properties with soil P values. Total soil P did not vary between land uses. Mehlich-3 extractable P was slightly higher in cropland soils due to higher concentrations in Forestdale and Sharkey soils. Dundee, Forestdale, and Sharkey cropland soils showed significant associations between Mehlich-3-extractable iron (Fe) and P. Ratios of total carbon (TC) to total nitrogen (C:N) and TC to P (C:P) were consistent across all sampled soil series but differed between forest and cropland soils. These ratios are critical for establishing baseline soil nutrient values in simulation models and can be used to improve water quality model simulations that help guide P management in the MAP. As Sharpley routinely demonstrated, understanding sources of P is critical for developing an appropriate management strategy. This study provides critical knowledge on soil P dynamics in the MAP region.

A Mechanochemically-Triggered, Self-Powered Flash Heating Synthesis of Phosphorous/Carbon Composites for Li-Ion Batteries.

"Flash heating" that transiently generates high temperatures above 1000°C has great potential in synthesizing new materials with unprecedently properties. Up to now, the realization of "flash heating" still relies on the external power, which requires sophisticated setups for vast energy input. In this study, a mechanochemically triggered, self-powered flash heating approach is proposed by harnessing the enthalpy from chemical reactions themselves. Through a model reaction between Mg3N2/carbon and P2O5, it is demonstrated that this self-powered flash heating is controllable and compatible with conventional devices. Benefit from the self-powered flash heating, the resulting product has a nanoporous structure with a uniform distribution of phosphorus (P) nanoparticles in carbon (C) nanobowls with strong P─-C bonds. Consequently, the P/C composite demonstrates remarkable energy storage performance in lithium-ion batteries, including high capacity (1417mAhg-1 at 0.2Ag-1), robust cyclic stability (935mAhg-1 at 2Ag-1 after 800 cycles, 91.6% retention), high-rate capability (739mAhg-1 at 20Ag-1), high loading performance (3.6mAhcm-2 after 100 cycles), and full cell cyclic stability (90% retention after 100 cycles). This work broadens the flash heating concept and can potentially find application in various fields.

Chemical Speciation and Preservation of Phosphorus in Sediments along the Southern Coast of Zhoushan Island

This study investigated the distribution of sedimentary phosphorus (P) species along an area of a rapid current at the southern coast of Zhoushan Island. The objective of this study was to improve the understanding of P cycling in a zone of rapid water cycling. Results showed that the average percentage of each P form to total P (TP) was in the following order: apatite P (Ca-P; 52%) was found in the most abundant, followed by organic P (OP; 16%), exchangeable-P (Ex-P; 14%), detrital P (De-P; 11%), and iron-bound P (Fe-P; 7%). Ca-P showed a trend of an increasing concentration from a location at the west (ZS1 has mean Ca-P = 45.6 mg kg−1) toward the east (ZS2 has mean Ca-P = 82.69 mg kg−1) and south-east (ZS3 has mean Ca-P = 82.17 mg kg−1); De-P also increased from 15.12 mg kg−1 at ZS1 to 22.53 mg kg−1 at ZS2 and 27.45 mg kg−1 at ZS3, but the three bioavailable P species, OP, Ex-P, and Fe-P, decreased from the west toward the east of the coastal area. Results along the cores showed the occurrences of sediment P adsorption and release throughout the time span from the 1930s to the present, with an overall trend of decreasing Ca-P and TP from the bottom to surface sediments. There was a tendency of Ca-P formation at the expense of Ex-P and OP release during transport and organic matter decomposition. The likely impact of climate change in the coastal zone would be an increased temperature resulting in elevated organic matter decomposition and P release.

A new steelmaking process using red mud as a fluorine-free flux: Promoting phosphorus removal and iron recovery

Bayer red mud, one of the most challenging solid wastes in the aluminum industry, is anticipated to be suitable for large-scale disposal in alignment with the specific requirements of the steelmaking process. This study determined the melting characteristics of various red mud-based fluxes using a high-temperature in-situ analysis system. Furthermore, the feasibility of large-scale application and the potential for substituting CaF2 in the iron and steelmaking process were investigated through a 10-kg induction furnace test and a 160-ton converter industrial test. The results indicate that the hot metal temperature during the pre-phosphorus removal stage ranged from 1254°C to 1430°C. Initial slag formation occurred within 2–4 minutes of oxygen blowing. The average slag basicity was between 1.5 and 2.1. Early dephosphorization and the average phosphorus distribution ratios were 41.4 %-63.4 % and 30, respectively. The mechanism of red mud-based fluxes in the early stage of steelmaking was further elucidated, and the application process was designed. The new process reduces the cost of slag materials, realizes the large-scale disposal of red mud, establishes the connection for the sustainable development of the steel and aluminum industries.