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Magnetic iron oxides are commonly enriched in soils and sediments on Earth's surface. Magnetic properties are widely employed in soil taxonomy, sediment tracing and paleoclimate reconstruction as indicators of associated pedogenic and depositional processes. However, in coastal regions, frequent shifts in pedogenesis and diagenesis accompanied by changes in hydrodynamic and geochemical conditions from land to sea can influence the formation and preservation of magnetic particles in sediment sequences. To discern the origin and nature of magnetic particles driven by these processes, we systematically examined soils and sediments around a tropical lagoon that has been closing for two hundred years. We found that the finest superparamagnetic particles are enriched along with hematite from inland soils with high‐Fe and high‐Al backgrounds, which was driven by pedogenesis. Single‐domain ferrimagnetic particles are enriched along with amorphous iron oxides in the lagoon with high‐Mg and high‐Mn backgrounds, which was driven by early diagenesis in quiet and reducing depositional environments. Coarse titanomagnetite particles are strongly enriched in inshore sediments with high‐Si and high‐Ti backgrounds, which was driven by seawater elutriation. However, magnetic particles in barrier bar soils have mixed features depending on the neighboring environment. Identifying magnetic particles derived from different soils and sediments in tropical coastal regions can assist in tropical coastal paleoclimate and paleoenvironment reconstruction on the basis of magnetic properties along coastal sediment sequences. Magnetic particles and iron oxides in soils and sediments can be used for sediment tracing and paleoclimate reconstructions. Interpretations are more complex in coastal environments and are accompanied by paleoenvironmental changes. In this study, we collected samples from around a tropical lagoon to systematically analyze the effects of different coastal locations on magnetic particles and iron oxides in soils and sediments. We find that the finest magnetic particles are enriched along with hematite in inland soils. Medium‐sized magnetic particles are enriched along with amorphous iron oxides in the lagoon in quiet and reducing environments. The coarsest magnetic particles are enriched in inshore sediments as a result of seawater waves. However, magnetic particles in barrier bar soils have mixed features depending on the surrounding environment. Our work assists in discerning magnetic iron oxides from different soils and sediments for paleoclimate and paleoenvironmental reconstruction research in tropical coastal areas. Soil and sediment samples around a tropical lagoon were analyzed via geochemical and magnetic methodsDifferent origins of magnetic particles are associated with hydrodynamic and geochemical backgroundsDifferent types of magnetic particles can be used to reconstruct coastal paleoenvironments Soil and sediment samples around a tropical lagoon were analyzed via geochemical and magnetic methods Different origins of magnetic particles are associated with hydrodynamic and geochemical backgrounds Different types of magnetic particles can be used to reconstruct coastal paleoenvironments

Goethite/hematite ratios in soils are widely used to reconstruct past climatic changes, but their accurate measurements have remained challenging due to the matrix effect. Here we present a new method for measuring soil goethite/hematite ratios by characterizing the band position of electron pair transition (EPT) based on the diffuse reflectance spectra processed by continuum removal. We introduce a “half‐band‐area wavelength”, λ1/2, to characterize the EPT band position and validate the method using synthetic standards made from mixing pure goethite and hematite and four sets of goethite‐ and hematite‐free matrices derived from arid aeolian deposits and tropical saprolite. A consistent λ1/2‐goethite/hematite relation across four matrices demonstrates that our method eliminates the matrix effect. We further validate our method by applying it to quantify goethite/hematite ratios in 180‐Kyr loess‐paleosol sequences and comparing the results to the reported paleoclimatic records. Our new method is promising for improving the measurement of goethite/hematite ratios in sediments. Hematite (α‐Fe2O3) and goethite (α‐FeOOH) are common iron oxides in soils and sediments. Their formation processes are sensitive to climatic conditions such as soil humidity. Thus, goethite/hematite ratios in terrestrial and marine deposits have been widely used to infer past climatic changes. However, their use relies on the accurate quantification of goethite/hematite ratios, which has been challenging using existing methods. Conventional X‐ray diffraction methods have high detection limits, whereas rock magnetic methods are limited by the weak magnetization of these minerals and the difficulty in converting magnetic moments to moles. Instead, methods based on diffuse reflectance spectra (DRS) have been frequently used to directly quantify goethite/hematite ratios given the high sensitivity, but major uncertainties exist due to the interference from the sample matrix. We developed a new DRS‐based method to quantify goethite/hematite ratios by characterizing the band position of electron pair transition (EPT). We find consistent statistically significant correlations between a proxy derived from the EPT band positions and goethite/hematite ratios across synthetic standards of different soil matrices, supporting that our method eliminates the matrix effect. Overall, we provided a promising method for precisely quantifying goethite/hematite ratios in soil and sediments. We present a new method for measuring goethite/hematite ratios using the band positions of electron pair transitionThe electron pair transition band position characterized by λ1/2is determined solely by the goethite/hematite ratios, not their contentsThe new method is independent of soil matrices and is validated by synthetic and geological samples We present a new method for measuring goethite/hematite ratios using the band positions of electron pair transition The electron pair transition band position characterized by λ1/2is determined solely by the goethite/hematite ratios, not their contents The new method is independent of soil matrices and is validated by synthetic and geological samples

Soil magnetism depends on the mineral composition and grain size distribution of magnetic particles. The accumulation of magnetic particles with different grain sizes has been found in the laboratory to precede the formation of hematite (Hm), which competes with goethite (Gt) in natural systems. To explore changes in the correlation between magnetic particles and Hm during pedogenesis, we focus on three representative red Ferrasol profiles with comparable total concentrations of iron oxides but different Hm/(Hm + Gt) ratios, from 0.14 to 0.74. Superparamagnetic particles and single‐domain particles commonly become enriched as the concentration of Hm increases in the profiles. However, the accumulation rates of the particles decrease with Hm/(Hm + Gt) along the profiles. We attributed these changes to the simultaneous grain growth of pedogenic magnetic particles and their partial transformation into Hm once a large amount of pedogenic magnetic particles have accumulated in hematitic soils. Grain growth of ferrimagnetic particles is revealed in red FerralsolsFormation rate of fine ferrimagnetic particles decreases as hematite increasesFerrimagnetic particles transform to hematite after being extremely enriched

Ferrimagnetic (FM) and antiferromagnetic (AFM) iron oxide particles are considered pedogenic and climatic indicators due to their enrichment with comparable increasing in rainfall and temperature. However, the opposite changes in rainfall and temperature result in rapid change of relative humidity (RH), which could lead to their competition and transformation. We examined two soil sequences which have undergone contrary climate development on the eastern edge of the Tibetan Plateau. Dry and warm climate with low RH favors the coordinative enrichment of AFM hematite and FM particles, while wet and cool climate with high RH mainly produces goethite but leads to competition between low content AFM hematite and FM particles. The outcome well interprets the changing relationship between color and magnetism in soils and sediments, and suggests that temperature is as important as precipitation in paleoclimate reconstruction based on iron oxides, especially during strong dry‐wet cycles and climate pattern shifts. Iron oxides are commonly enriched on the surface of Earth as weathering products driven by comparable increases of rainfall and temperature. Color and magnetism of soils dominated by antiferromagnetic (AFM) and ferrimagnetic (FM) iron oxides may present sensitive pedogenic and climatic indicators. However, contrary changes in rainfall and temperature often lead to remarkably changing relative humidity (RH) which could promote their competition and transformation into iron hydroxides. The uplift of the Tibetan Plateau has led to different orographic elevation and differential climate development on the eastern edge on the Yunnan Plateau and the Guizhou Plateau. We found that the present dry and warm climate on the Yunnan Plateau with low RH favors the dehydration of amorphous iron oxides to form AFM hematite and FM particles concomitantly, while the present wet and cool climate on the Guizhou Plateau with high RH mainly produces goethite and leads to a competitive development of AFM hematite at low concentration and FM particles. These conditions explain the variable relationship of magnetism and color in soils and sediments. It is also suggested that temperature is as important as precipitation when reconstructing paleoclimate based on iron oxides, especially during strong dry‐wet cycles and climate shifts. Dry and warm climate favors the dehydration of amorphous iron oxides to form antiferromagnetic hematite and ferrimagnetic particlesWet and cool climate mainly produces goethite and leads to the competition between antiferromagnetic hematite and ferrimagnetic particlesTemperature is as important as precipitation when reconstructing paleoclimate with strong dry‐wet cycles and climate pattern shifts Dry and warm climate favors the dehydration of amorphous iron oxides to form antiferromagnetic hematite and ferrimagnetic particles Wet and cool climate mainly produces goethite and leads to the competition between antiferromagnetic hematite and ferrimagnetic particles Temperature is as important as precipitation when reconstructing paleoclimate with strong dry‐wet cycles and climate pattern shifts

Magnetic particles associated with iron (Fe) oxides are widespread on the surface of Earth and Mars and serve as reasonable climatic indicators. Ferrimagnetic maghemite (Mgh) and antiferromagnetic hematite (Hm), which dominate magnetism and redness, often coexist or compete with each other in soils and sediments. The formation efficiency of Mgh relative to Hm could be modulated by geochemical background besides climate, especially by phosphate (P), which has a high affinity for the surfaces of precursor iron oxides in natural systems. We investigated two Ferralsol sequences around a P mining field with similar climates and contrasting P/Fe ratios. High P/Fe ratios retard iron oxide crystallization, grain growth, and transformation into Hm, thereby promoting more effective accumulation of ferrimagnetic Mgh as an intermediate product. The lack of ligand‐protected effects well interprets asynchronous changes in magnetism and redness in soils and sediments across large spatiotemporal scales, especially in highly weathered soils. Iron oxides are critical carriers of magnetism and dyeing agents of soils and sediments. The concentration of pedogenic maghemite (Mgh) and hematite (Hm), which dominate magnetism and redness, is considered to be controlled by the primary iron input and climate conditions. However, phosphate exhibits a high affinity for the surfaces of precursor iron oxides, especially in highly weathered soils. We investigated two Ferralsol sequences around a P mining field with contrasting P/Fe ratios but similar climates. High P/Fe ratios are observed to impede iron oxide crystallization, grain growth, and transformation into Hm, thereby promoting more effective accumulation of ferrimagnetic Mgh as an intermediate product. The presence and absence of ligand‐protected effects help explain asynchronous changes in magnetism and color in nature systems across large spatiotemporal scales. Iron oxide crystallinity increases monotonically as soil P/Fe decreasesFerrimagnets accompanying the formation of hematite are enriched with accelerations under high P/Fe but with even rates under low P/FeFerrimagnets grow and transform into hematite more rapidly without the proper level of P ligand protection

With the continuous development of the strategy of the development of the western region and the gradual advancement of the "One Belt, One Road" strategy, Xianyang Airport serves as the gateway for foreign exchanges in Xi'an, and the passenger and freight traffic volume has increased year by year. This article is based on the passenger and cargo traffic that has been available from 2009 to 2015. We will use the trend extrapolation method, the econometric method and the market share method to predict the passenger and cargo transportation volume from 2016 to 2018, comparing with the actual passenger and cargo transportation volume. Then we can obtain the annual error, and find the average error. According to the average error, the weights are determined. Finally, we combine the result with its weight, comparing with accurate result, and get more exact result. Therefore, this method is applied to the forecast of aviation traffic from 2019 to 2023, and then more accurate results are obtained. According to the air passenger and cargo transportation volume in the next five years, combined with the basic economic and population conditions, it will provide reference for the future development and functional positioning of Xianyang Airport.