Metal Patterns Research Articles

Metamaterial microwave sensor with ultrahigh Q-factor based on narrow-band absorption

A novel metamaterial sensor with ultrahigh Q-factor of 665.85 and 1883.3 at 5.46 GHz and 11.3 GHz is presented in this paper, which consists of a metal pattern with cross structure and ring (CSR), a dielectric slab FR4 and a metal backplate. Based on the principle of the absorber, the Q-factor of the two resonance frequency points is improved by optimizing the ring and cross structure to strengthen the resonance. It is because of its wide angle incidence, insensitive polarization, and narrow-band absorptivity greater than 90 %, which is very conducive to the design of material refractive index sensor. Equivalent circuit method is used to analyze the characteristic of the metamaterial structure and the experimental results are in good agreement with the simulations. By loading three giving materials, the sensing function is analyzed and verified in experiments. The design has the advantages of ultrahigh Q-factor, angle and polarization insensitivity, and has potential application prospects in metamaterial sensing.

Spatial patterns of PM2.5-bound heavy metals and analysis of their influencing factors in China

This study investigates the relationship between the spatial distribution patterns of heavy metals (HMs) in atmospheric fine particulate matter (PM2.5) and their influencing factors in China, in order to address air pollution problems. Using HM data from PM2.5 collected from 88 Chinese cities between 2012 and 2020, the study employed a combination of enrichment factor (EF) analysis, standard deviation ellipses and hot spot analysis to assess spatial distribution patterns; geographical detectors to identify influencing factors; and hybrid single-particle Lagrangian integrated trajectory models (HYSPLIT) to determine air mass movement. The results reveal that the spatial distribution of PM2.5-bound HMs in China is characterized by high levels in the north and interior and low levels in the south and along the coast. Anthropogenic activities affect HM levels in China's interior more strongly than on the coast. Moreover, the distribution of PM2.5-bound HMs in China exhibits a northeast-southwest spatial pattern, with significantly higher levels observed in central and northern regions than in eastern regions, particularly along the coast. Industrial waste emissions and energy consumption are key factors contributing to high PM2.5-bound HMs. In central China, the summer air mass movement predominantly follows a southeast direction, while in winter, it follows a northwest direction, originating from inland. In contrast, in eastern China, summer air mass movement predominantly follows a southeast direction, while in winter, it follows a northeast direction, originating from the ocean. Overall, our findings suggest that HMs in PM2.5 display high clustering values in central China, due primarily to industrial waste emissions, energy consumption, and air mass movement.

The direct experimental observation and solidification mechanism of heavy metals in blast furnace slag glass‐ceramics

AbstractGlass‐ceramics with high performance and high crystallinity was produced using rare earth blast furnace slag (REBFS) as the primary raw material, along with composite nucleating agents Fe2O3 and Cr2O3. The migration pattern, distribution characteristics, and solidification properties of heavy metals in glass‐ceramics were investigated by the controlled heat treatment. The findings indicated that the heat treatment temperature has a significant effect on the distribution and color of heavy metals in glass‐ceramic. In the crystallized glass‐ceramic, spinel acts as the crystal core for heavy metal solidification, Cr, Cu, and Mn can exist stably in the spinel by the solid solution. The glass‐ceramic was expected to be used as a decorative building material.

Epoxy Resin-Assisted Cu Catalytic Printing for Flexible Cu Conductors on Smooth and Rough Substrates.

Flexible copper conductors have been extensively utilized in flexible and wearable electronics. They can be fabricated by using a variety of patterning techniques such as vacuum deposition, photolithography, and various printing techniques. However, vacuum deposition and photolithography are costly and result in material wastage. Moreover, traditional printing inks require posttreatment, which can damage flexible substrates, or grafting polymers, which involve complex processes to adhere to flexible substrates. Therefore, this study proposes a facile method of fabricating flexible metal patterns with high electrical conductivities and remarkable bonding forces on a diverse range of flexible substrates. Catalytic ink was prepared by using a mixture of epoxy resin, copper nanopowder, and nanosilica. The ink was applied to a variety of flexible substrates, including a poly(ethylene terephthalate) (PET) film, polyimide film, and filter paper, using screen printing to establish a bridge layer for subsequent electroless deposition (ELD). The catalytic efficiency was significantly improved by treating the cured ink patterns with air plasma. The fabricated flexible metals exhibited excellent adhesion and desirable electrical conductivity. The sheet resistance of the copper layer on the PET substrate decreased to 9.2 mΩ/□ after 150 min of ELD. The resistance of the flexible metal on the PET substrate increased by only 3.125% after 5000 bending cycles. The flexible metals prepared in this study demonstrated good foldability, and the samples with filter paper and PET substrates failed after 40 and 70 folds, respectively. A pressure sensor with a bottom electrode consisting of a copper interdigital electrode on a PET substrate displayed favorable sensing performance.

Otolith microchemistry of freshwater indigenous minor carp (Bangana dero) as a biomonitoring tool to trace heavy metals in River Sutlej, Ropar Wetland (Ramsar site), Punjab, India.

The elemental composition of the fish otolith may represent a permanent record of the environmental condition the fish inhabited. Fish otolith grows incrementally from the core to a marginal region that acts as a repository of trace metal signatures. The present study explores the potential application of otolith microchemistry of the benthopelagic indigenous minor carp Bangana dero sampled from the Ropar wetland on River Sutlej, Punjab. The concentration of sixteen metals was evaluated in the otolith (n = 42) and water (n = 48) for the post-monsoon and pre-monsoon season from 2020 to 2022 using inductively coupled plasma mass spectrometry (ICP-MS) followed by element detection in the core and marginal region of whole otolith, using energy-dispersive mass spectroscopy (EDS). All the heavy metals exhibited an increase in metal concentrations in fish otolith than water during the post-monsoon season. By indices approach, the otolith was found to have a high bioaccumulation factor for Se in the post-monsoon and Hg in the pre-monsoon. Certain trace metals like As and Hg exhibited fluctuations in their core and marginal region. Thus, trace metal patterns in the otolith could act as a potential tool for monitoring the seasonal changes of metals in water bodies. The EFHg, EFSe and EFAs in the fish otolith predicted its anthropogenic source, while the remaining studied elements showed ambient water origin. Thus, using the otoliths of Bangana dero as a long-term monitoring tool in the future may be helpful for environmental assessments and the reconstruction of historical exposure for safeguarding of water bodies.

Estimation of the distribution patterns of heavy metal in soil from airborne hyperspectral imagery based on spectral absorption characteristics

Though soil is widely known as one of the most valuable resources for the world, its quality is going to be lower because of unsustainable economic development and social progress. Therefore, it is important for us to monitor and evaluate the quality of soil, especially its heavy metal contents which is too scarce to identify in soil spectra easily but poisonous enough to affect human health in a long run. Most of the existing estimation methods have based the characteristic bands on statistical analysis to a large extent, which is hard to accurately explain the retrieval mechanism. In this paper, the absorption characteristics of heavy metal are studied based on the soil spectra, and the distribution pattern is mapped in a large-scale continuous space, for environmental monitoring and further decision support. Taking Yitong County, China as the study area. After spectra continuum removal, the heavy metal contents were estimated by 11 features including the absorption depth, absorption area, and band ratio around 2200 nm, which showed the best performance. For arsenic (As), the best model yields Rp2 value of 0.8474, and the RMSEP value is 36.1542 (mg/kg). It is concluded that As is adsorbed by organic matter, clay minerals, and iron/manganese oxides in soil, and the adsorption of As by first two components is greater than that of the last. For airborne spectra after continuum removal, combining the spectral absorption characteristic parameters and the highly correlated bands is more accurate than using the spectral absorption characteristic parameters or bands alone. AdaBoost is presented for the heavy metal estimation, and the fitting ability of the method is found to be stronger than that of the traditional classical methods, with the Rp2 values of 0.6242 and the RMSEP value of 43.6481 (mg/kg). In summary, these results will provide a prospective basis for the rapid estimation of soil heavy metals, the risk assessment of soil heavy metals and soil environmental monitoring in a large scale.

World Output and Commodity Price Cycles*

This study investigates the cyclical patterns of energy, agriculture, and metals and minerals (MetMin) commodity prices. We identify three super cycles since 1960, and a potential fourth arising from the Ukraine crisis and global COVID-19 pandemic. Employing a Structural Vector Autoregression (SVAR) approach, we establish an empirical relationship between output, CPI, and commodity prices. Our analysis reveals that an output shock leads to a general increase in all commodity prices, where the highest impact is on energy inflation. Moreover, we examine the heterogeneous effects of commodity inflation on overall inflation, uncovering ‘second round' effects across all commodities. Notably, agriculture inflation has the most significant impact on aggregate inflation, potentially explaining the destabilizing nature of food inflation in many countries. Our findings enhance understanding of these dynamics, offering important insights for policymakers and informing the public. Highlights We analyze the cyclical patterns of energy, agriculture and MetMin commodity prices. Real output, CPI and commodities exhibit the same cyclical patterns. A shock to output increases all commodities, where the highest response is energy inflation. We find ‘second-round' effects, where agriculture prices have the highest impact on inflation.

Distribution of heavy metals in water and sediment at the Bojonegara nearshore of Banten Bay, Indonesia

Heavy metals released to a nearshore environment may vary due to contaminant sources and the seasonally coastal processes. This study revealed how the seasonal variability and potential sources controlled the distribution pattern of several heavy metals and the level of water quality in Bojonegara nearshore of Banten Bay. The water and sediment samples were collected once in January, February, August, September, and October 2020 at six stations representing the river and sea. Heavy metal was determined using the APHA procedure. Cu was detected in August-October, ranging from <0.002 – 0.008 mg/L. The concentrations of Cu, Cd, and Pb in the sediment were detected, varying from <0.02 to 3.90 mg/kg, <0.02-1.68 mg/kg, and <0.02-6.71 mg/kg, respectively. The concentrations of the concerned metals in sediment vary, and their distribution pattern change seasonally. These metals in water and sediments were still safe for the environment and marine biota. This study suggests how contaminant sources and coastal processes could control the contaminant level. In addition, potential sources of heavy metal merely derived from onshore of the Bojonegara, but it could be derived from advection from other areas through the coastal processes.

Numerical analysis of the behavior of molten pool and the suppression mechanism of undercut defect in TIG-MIG hybrid welding

In order to investigate the multi-coupling transport phenomena in TIG-MIG hybrid arc welding, a three-dimensional model including droplet and molten pool was established. An innovative distribution pattern of arc heat and force that adapted to the evolution of molten pool surface was proposed, achieving a unified distribution of "arc current density-arc pressure-electromagnetic force-arc heat". The effect of TIG arc on molten pool behavior and undercut defect was quantitatively analyzed by comparing TIG-MIG hybrid welding with traditional MIG welding. The results showed that the electromagnetic repulsion between the two arcs with opposite currents increased the aspect ratio of the hybrid arc heat and force distribution. It led to a long and narrow gouging region, where the promoting effect of inertial force on the undercut was weakened by arc pressure and hydrostatic pressure. The liquid metal with a lower cooling rate had sufficient time to fully fill the weld toe and suppressed undercut. Sensitivity and dimensional analysis illustrated that the TIG-MIG hybrid arc eliminated undercut by reducing the inertia force, adjusting the arc pressure distribution, and enhancing the hydrostatic pressure. The groove sizes was predicated based on molten pool characteristics, including the stress state of liquid metal, morphology, and fluid flow patterns. It revealed the quantitative relationships among welding parameters, behavior of molten pool, and weld bead formation, promoting the implementation of digital twinning technology in the manufacturing industries.

Terrigenous humic substances regulate the concentrations of dissolved Fe and Cu (but not Al, Mn, Ni or Zn) in the Gaoping River plume

The small mountainous rivers of Oceania discharge a large fraction of their dissolved and particulate load of materials within a very small percentage of the time. As a result, the yearly inputs and physicochemical forms of dissolved metals exported to the ocean by these rivers are poorly quantified. We investigated the wet-season distribution patterns of metals and fluorescent organic substances in the surface waters of the Gaoping River plume, SW Taiwan, under both moderate (Sep 2020) and strong flow conditions (Aug 2021). The mixing behaviour of both soluble (<5 kDa) and colloidal (>5 kDa) metals and fluorescent components was examined over the salinity range 3.0–32.2 in 2020 and 5.8–31.1 in 2021. We detected two humic-like and one protein-like fluorescent components, the same on both surveys. The humic-like components, C1 and C3, originated from the Gaoping River and correlated strongly with Cu and Fe, respectively. Component C3 showed a greater enrichment relative to C1 in the colloidal (C3/C1 > 0.8) than in the soluble phase (C3/C1 = 0.4). The protein-like component, C2, came from both terrestrial and marine sources and displayed a more complex mixing behaviour than the other two. One striking result was that the effective zero-salinity concentrations of Fe (∼300 nM) and Cu (∼23 nM) did not change significantly in response to a 10-fold increase in river discharge between Sep 2020 and Aug 2021. Similarly to Fe and Cu, the distribution patterns of Components C1 and C3 did not change significantly between the moderate and the strong plume, and C3 and C1 correlated strongly with Fe and Cu, respectively. We conclude that subtropical mountainous rivers can provide soil-derived humic substances which facilitate and regulate the delivery of Fe and Cu to the ocean, provided mountain forests are preserved.

A double-layer Huygens’ metasurface with complete phase coverage and its dual-polarized meta-lens antenna application

A novel double-layer Huygens’ unit with dual-polarized response and complete phase coverage has been proposed for highly efficient meta-lens antenna application. The designed unit is a symmetric structure in which the double-layer metallic patterns not only act as the electric dipoles but also induce the magnetic dipoles. The balance between the initial electric dipole and the induced magnetic dipole makes the impedance of the metasurface match with that of free space, thus allowing efficient transmission of electromagnetic waves. Moreover, full transmission phase shift and near-unit transmission amplitude can be achieved simultaneously by change the structural parameters of the unit. Utilizing such electromagnetic properties, a dual-polarized meta-lens consisting of 35 × 35 units with size of 161 × 161 mm2 is designed, fabricated and measured. The results exhibit its good radiation performance. The maximum gain at a frequency of 28 GHz reaches 30.8 dBi, with an aperture efficiency of 42.3%. The 3-dB gain bandwidth reaches 12.5%, covering the frequency range of 26.7–30.2 GHz. The simple structure of the designed dual-polarized metasurface, high gain and high antenna efficiency make it an important antenna engineering role.

Assessment of Heavy Metals on African Catfish (Clarias gariepinus) from Some Fish Ponds in Emene, Enugu State, South-East Nigeria

The research was conducted to determine the presence and bioaccumulation pattern of some heavy metals in African catfish (Clarias gariepinus) from three fish ponds in Emene, Enugu State, South-East Nigeria. Fish samples used for the analysis were collected during the dry season from Tollex, Sopulu and Nduka pond farms. The analysis of heavy metals: lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), zinc (Zn), and iron (Fe), in C. gariepinus gills and muscles was carried out using atomic absorption spectrophotometer (AAS) after digestion with concentrated HCl. Results of the analysis show that the investigated heavy metal in the fish samples from the ponds on the basis of their average concentration followed the order: Sopulu pond &gt; Nduka pond &gt; Tollex pond with highest concentration (7.427 ppm of Fe) found in the gill of fish from Sopulu fish pond and lowest concentration (0.013 ppm of Cd) in the muscle of fish from Tollex fish farm. The study has shown that there was a considerable amount of heavy metals in the muscle and gills of catfish from Tollex, Nduka and Sopulu fish farms.

Realization of thick copper conductive patterns using highly viscous copper oxide (CuO) nanoparticle ink and green laser sintering

The demand for lower-cost and higher-thickness metallic conductive patterns is increasing in printed electronics. Copper oxide (CuO) nanoparticle (NP) ink is a promising low-cost alternative to other metal-based nanoparticle inks such as Au and Ag. In order to obtain thick printed patterns using high viscosity (207,000 cPs) CuO NP ink, a time-pressure dispenser developed in our laboratory was used. After printing the CuO patterns, we used a continuous wave (CW) green laser with a 532 nm wavelength to reduce the CuO to Cu and sinter the reduced Cu nanoparticles. However, the laser absorption depth is known to be only a few dozens of nanometers. Therefore, when the thickness of CuO patterns exceeds 10 μm, it is unclear whether the reduction and sintering can be uniformly achieved through the thickness direction. We investigated the effects of different sintering parameters on the conversion of a thick CuO nanoparticle layer with a thickness of about 34 μm to form Cu conductive patterns. Under optimal sintering conditions, we obtained a resistivity of 8.75 μΩ·cm for a Cu conductive pattern with a width of 1 mm and a thickness of 18.4 μm, which is five times higher than the bulk resistivity. After creating Cu conductive patterns, we assessed their reliability by exposing them to elevated temperatures in an air atmosphere. The findings demonstrate notable resistance to oxidation at a temperature of 250 °C for a duration of 4 h.

Volatilization characteristic and solidification of Pb, Zn, Cd and as during cement kiln co-processing of solid waste

Cement kiln co-processing always became one of the predominate approaches to dispose hazardous solid waste containing heavy metals. The volatilization and morphology of heavy metals should be paid to more concern during the cement production due to the environmental risk of heavy metals. In this study, the volatilization characteristics and the solidification effect of heavy metals (Pb, Zn Cd and As) during cement kiln co-processing were explored by the lab and pilot scale experiments. At same experimental conditions, the volatilization rate followed as As > Pb > Cd > Zn. Both limestone and cement raw meal have been demonstrated the capability to mitigate the rates of heavy metal volatilization. Notably, cement raw meal displays a more pronounced effect compared to limestone in suppressing volatilization processes. Over 50% of heavy metals were transformed into residual state at 1400 °C, and Cd, As and Zn were easy to be solidified than Pb. A pilot scale experiment proved that more than 80% of heavy metals was solidified, and Zn reached nearly 100%. Moreover, around 80% of Cd, As and Zn were remained in clinker and the rest was distributed in kiln dust particles, only very few amount was released into the exhaust flue gas. This study provides a comprehensive and extensive understanding of the volatilization characteristics and migration patterns of heavy metals in the cement kiln environment. It offers theoretical support for the control of heavy metals during the co-processing of hazardous solid waste in cement kilns.

Investigating Polarization-Sensitive Transmission and Reflection Metasurfaces for Advanced Wavefront Manipulation

This paper presents the design and optimization of a dual-band polarization-dependent metasurface capable of dynamically switching transmission and reflection characteristics. The metasurface is composed of three metallic patterns, with the bottom layer governing the reflection and transmission phase for both TE-polarization and TM-polarization states. The middle and top layers are strategically employed to ensure optimal transmission and reflection performance. The results confirm that the metasurface enables the transformation of the transmission band into a complete reflection band, and vice versa, through variations in the incident wave polarization. Remarkable transmission and reflection characteristics are achieved within the frequency ranges of 6.1–6.55 GHz and 8.9–9.3 GHz, respectively. The proposed metasurface offers promising applications in advanced communication systems and radar technology, enabling dynamic manipulation of electromagnetic waves.

Transmissive laser lock-in thermography for highly sensitive and online imaging of real interfacial bubbles in wafer bonding

Online and non-destructive detection of interfacial bubbles in wafer bonding is a critical approach to enhance the yield of advanced packaging. However, the commonly used scanning acoustic microscopy (SAM) is time-consuming and may cause additional risk due to soaking in water. The conventional thermography is suffering from low sensitivity and resolution. In this work, we demonstrate for the first time an effective method for highly sensitive and online imaging of real interfacial bubbles in wafer bonding using transmissive laser lock-in thermography (LLT). The transmissive LLT system projects a modulated laser beam onto target wafer surface and records the thermal image sequence on the other side. The bubbles distinctly emerge with clear edges in the extracted lock-in phase images. To enhance the detectivity, the relationship between phase image contrast and LLT parameters was explored. As a result, we can visualize and detect the bubbles larger than 500 μm at depth of 725 μm even under the interference of metal pattern with a speed of 130 mm2/10 s, which is 38% faster than that of SAM. Besides, the LLT phase images contain both bubbles and metal patterns information. The ratio between bubble depth and width reaches 1.45, which is about 2-fold of the latest infrared researches. Above all, this work paves the way for high-sensitive imaging of various tiny internal defects in advanced packaging using infrared thermography.

Moving metals V: The question of shared copper sources between Scandinavia and Hungary 1700–1500 BC

The remarkable typological parallels between Carpathian and Scandinavian metalwork, especially from around 1700 to 1500 BC, have long been stressed as evidence that the Carpathian tell communities supplied the Scandinavians with copper. Thus, this study's main objective was to investigate if Bronze Age societies in Scandinavia and the Carpathian basin utilized the same copper sources. To test this hypothesis, analyses, comprising lead isotopes and trace elements, were executed on bronzes from Scandinavia and Hungary. In the current study, the Hungarian data set of 31 artefacts from the famous Százhalombatta hoard and its nearby settlement, is in detail compared to 62 Scandinavian artefacts of various types. The outcome points to that Scandinavia and Hungary partly shared copper sources between 1700 and 1500 BC. The most potential sources are the ones from the Slovak Ore Mountains and Mitterberg in Austria. However, the Scandinavian artefacts from this period also show consistency with additional copper sources, such as Great Orme in Wales and in the Italian Alps. The findings of this study support both the traditional theory, which stated that metal supplies and metalworking traditions were closely related, and the more recent insight, which suggests that style and content may have entirely separate origins. As a result, the intricacy of the production, exchange, and consumption patterns of metal throughout Bronze Age Europe cannot be explained by a simple model that equates stylistic influence and metal suppliers.

EMC Hybrid Loop/Monopole LDS Antenna With Three-Sided Ground Walls for 2.4/5/6 GHz WLAN Operation

A multi-resonant, electromagnetic-compatible (EMC), hybrid laser- direct-structuring (LDS) antenna capable of operating in the 2.4, 5, and new 6 GHz wireless local area network (WLAN) bands is presented. The LDS metal patterns are formed on a holder with the volume of 8 mm × 10 mm × 30 mm and comprise an inner loop, a parasitic strip, and three-sided, vertical ground walls. The fundamental and the first higher-order resonance of the parasitic strip acting as a shorted monopole generate the 2460 and 6460 MHz modes. In addition, two loop modes formed by the inner loop with the parasitic strip and the inner loop only, respectively, contribute to the 5420 and 7020 MHz resonance. All of these together generate a tri-WLAN-band, 2.4/5/6 GHz operation. The vertical ground also functions as the shielding walls that assorted conductive components can be placed in the close vicinity of the design for compact integration. The proposed antenna applied to laptop computers for the most recent Wi-Fi 6E operation is demonstrated in this article.

(Invited) Aerosol Jet and Laser Assisted Electrochemical Deposition for Advanced Metallization

The inkjet printing technology for conductive patterns is commonly conducted with inks that are made of metal nanoparticles or based on metal-organic decomposition. An additional step of sintering, which is usually done in oven or on a hot plate, is required after inkjet printing to obtain metallic patterns with desired electrical conductivity [1]. Laser-induced selective metal deposition on metallic and non-metallic substrates has been the subject of much attention recently. An induced deposition rate several orders of magnitude greater than conventional rates is claimed to occur at points where a laser beam impinges the electrode surface [2].In this work, electrolytic and electroless deposition processes are combined with aerosol jet technology and laser assisted setups to induce local metallization on metallic and non-metallic substrates. Single metals and alloys deposition will be discussed according to compatibility with the substrates, selectivity and achievable feature size. Examples of microfabrication and selective decorative applications will be provided, together with an evaluation of the properties of the produced deposits. J-J. Chen, Fabrication of conductive copper patterns using reactive inkjet printing followed by two-step electroless plating, Applied Surface Science 396 (2017) 202–207.R. Khan, Laser-Induced Selective Deposition on Metal Using Electroless Gold, NASF SURFACE TECHNOLOGY WHITE PAPERS 84 (2019) 6-13.

Roles of dissolved organic matter (DOM) in shaping the distribution pattern of heavy metal in the Yangtze River

Dissolved organic matter (DOM) strongly influences the solid-liquid partitioning and migration characteristics of heavy metals, yet little is known about the metal distribution and risk with the participation of DOM in large riverine systems. This study investigated the spatiotemporal distribution of 14 heavy metals and DOM along the entire Yangtze River (over 6000 km), and highlighted the critical roles of DOM in regulating the environmental behaviors of heavy metals. Significant spatial variations of metal contents were observed, with the river source and lower reach remarkably different from the upper-middle reaches. Heavy metals in the Yangtze River were mainly from the natural sources with minor anthropogenic disturbance. We found DOM could promote the conversion of metals from solid to liquid phase and DOM with higher aromaticity showed higher metal affinities. Although low ecological risks were observed in the Yangtze River, potential risks of metal leaching warrant attention, especially for As, Cd and Sb in the middle-lower reaches with higher DOM content and aromaticity. This study established a source-to-sea investigative approach to evaluate the influences of DOM features on metal partitioning, which is crucial for the risk control and sustainable management of large rivers.