Attenuation Mechanism Research Articles

Carbon based Composite Materials for Microwave Absorption in Low Frequency S and C Band: A Review

AbstractWith the rapid advancement of 5G technologies and electronic devices, there is a growing demand for microwave absorbing materials, especially those effective in low frequency microwave bands (2–8 GHz), making it an essential requirement. In recent years, many innovative microwave absorbers have been developed for low frequency absorption, with carbon/magnetic composite materials becoming particularly promising due to their various loss mechanisms and optimized impedance matching characteristics over a wide frequency range. However, there is currently a lack of a comprehensive review that summarizes the findings on low frequency absorbers. This review article thoroughly examines the current research on carbon/magnetic composite materials with efficient absorption performance in the low‐frequency S and C bands. It provides a detailed discussion of the microwave absorption performance of these composite materials. Furthermore, the composite design strategies, synthesis techniques, microstructure performance relationship, and microwave attenuation mechanisms are summarized. Lastly, the challenges and future outlook for low frequency microwave absorbing materials are addressed. This review article aspires to provide new insights into designing and synthesizing composite materials to accomplish effective low‐frequency microwave absorption, thereby promoting practical applications.

NusG-dependent RNA polymerase pausing is a common feature of riboswitch regulatory mechanisms.

Transcription by RNA polymerase is punctuated by transient pausing events. Pausing provides time for RNA folding and binding of regulatory factors to the paused elongation complex. We previously identified 1600 NusG-dependent pauses throughout the Bacillus subtilis genome, with ∼20% localized to 5' leader regions, suggesting a regulatory role for these pauses. We examined pauses associated with known riboswitches to determine whether pausing is a common feature of these mechanisms. NusG-dependent pauses in the fmnP, tenA, mgtE, lysP and mtnK riboswitches were in strategic positions preceding the critical decision between the formation of alternative antiterminator or terminator structures, which is a critical feature of transcription attenuation mechanisms. In vitro transcription assays demonstrated that pausing increased the frequency of termination in the presence of the cognate ligand. NusG-dependent pausing also reduced the ligand concentration required for efficient termination. In vivo expression studies with transcriptional fusions confirmed that NusG-dependent pausing is a critical component of each riboswitch mechanism. Our results indicate that pausing enables cells to sense a broader range of ligand concentrations for fine-tuning riboswitch attenuation mechanisms.

Construction of cobalt zinc metal-organic frameworks derived Co/CoO/C composites toward broadband and high-efficiency electromagnetic wave absorption

The fabrication of novel carbon-based electromagnetic wave (EMW) absorbers with broad absorption bandwidth, strong absorption strength, low filler loading ratio and thin matching thickness remains a challenging task. Metal-organic frameworks (MOFs) are widely recognized as ideal self-sacrificial templates for the construction of carbon-based EMW absorbers. In this work, bimetallic CoZn-MOFs derived Co/CoO/C composites were prepared by combining magnetic stirring with subsequent pyrolysis treatment. The results showed that the morphology of carbon skeletons evolved from an irregular agglomerate to a uniform hexagonal star shape and then to an agglomerate again by reducing the molar ratio of Co2+ to Zn2+. Remarkably, excellent EMW absorption capacity in the Ku-band was achieved through carefully regulating the molar ratio of Co2+ to Zn2+. When the filling ratio was 20wt.%, the prepared Co/CoO/C composite exhibited the best EMW absorption performance with the minimum reflection loss of -64 dB at a thickness of 1.79mm and the maximum effective absorption bandwidth of 6GHz at a thickness of 2.14mm. Furthermore, the radar cross section in the far-field was simulated by computer simulation technique. In addition, the possible EMW attenuation mechanism was proposed. Therefore, the results of this paper could be helpful for developing carbon-based magnetic composites derived from MOFs as broadband and high-efficiency EMW absorbers.

Fabrication and electromagnetic wave absorption modulation of high-performance (TaNbTiV)₂AlC MAX Phase

Electromagnetic (EM) wave technology is widely used in both military and civilian applications, increasing interest in EM wave absorption materials for information security and environmental protection. This study examines the synthesis and EM wave absorption properties of M-site compositional complex MAX phase (TaNbTiV)2AlC. Using Ta, Nb, Ti, V, Al, and graphite powders, pure (TaNbTiV)2AlC was synthesized at 1400°C. SEM and EDS confirmed homogeneous elemental distribution and morphology, while TEM and SAED analyses revealed the atomic structure. EM wave absorption was tested using (TaNbTiV)2AlC/paraffin wax composites with varying (TaNbTiV)2AlC content in the 2-18 GHz range. The main attenuation mechanisms identified were interfacial polarization, dielectric loss, and conductive loss. Optimal absorption was achieved at 30 vol% (TaNbTiV)2AlC, with a reflection loss of -43.83 dB and an effective absorption bandwidth of 3.49 GHz. The study demonstrates that the control of establishing a “near-conductive network” of fillers could be advantageous in achieving optimal electromagnetic wave absorption performance using fillers possessing high electrical conductivity, such as MAX phase materials.

Crustal Heterogeneity of the Bhutan Himalaya: Insights from PgQ Tomography

Abstract We present the results of a seismic investigation conducted in Bhutan using data from the Geodynamics and Seismic Structure of the Eastern Himalaya Region broadband network, focusing on variations in crustal structure and seismic attenuation properties. Through analysis of seismic data from 56 events recorded between 2013 and 2014, with magnitudes exceeding 4.5 and depths shallower than 50 km, we examined 1 Hz PgQ (Q0)-values among multiple station pairs using the two-station method. Our findings reveal significant disparities in PgQ0-values across Bhutan. The western region exhibits low PgQ0 values, indicating high seismic attenuation, whereas the central region shows medium-to-high PgQ0 values, suggesting lower attenuation. Notably, these results are consistent with the geometry of the Moho, providing valuable insights into crustal geometry and rheology. This study contributes to a deeper understanding of Bhutan’s complex crustal structure, offering insights into crustal properties and seismic attenuation mechanisms in this geologically significant region.

Triple‐structured polyvinylidene fluoride‐based composite films with high conductivity and EM shielding properties

AbstractFunctionalized thin films with excellent flexibility and conductivity can meet the current requirements for electromagnetic(EM) shielding materials. In this paper, 2D transitions metal carbide and nitride nanomaterials Ti3C2Tx MXene were prepared by chemical exfoliation, and PVDF/MWCNTs/3 wt%/RGO@Fe3O4@ AgNWs‐10 based on PVDF/MWCNTs‐3 wt%/RGO@Fe3O4@AgNWs‐10, The samples were prepared through a simple solution mixing process followed by vacuum‐assisted filtration (VAF), and PVDF/MWCNTs/MXene/RGO@Fe3O4@AgNWs three‐layer PVDF‐based composite films, which were analyzed for electrical conductivity and EM shielding properties, which increased and then decreased with the rise in the Ti3C2Tx MXene content, in which the highest electrical conductivity of the three‐layer composite films of M3/MX‐10/R@F@Ag was obtained when the Ti3C2Tx MXene addition amount reached 10 mL as 3.9 × 103 S/m, the EMI SET is 54.9 dB, the EMI SEA is 44.8 dB, the absorption loss is 81.6%, and the SSEt of the M3/MX‐10/R@F@Ag three‐layer composite film is the highest 1672.5 dB/(cm−2·g). And the SEA/SER ratios of the M3/MX‐X/R@F@Ag three‐layer composite films are all greater than 1. The result shows that the EM attenuation mechanism of the M3/MX‐X/R@F@Ag three‐layer composite films is primarily driven by absorption loss and that the incorporation of Ti3C2Tx Mxene improves the EM shielding performance of the composite films. The relatively novel exploration of the performance study and structural design of the M3/MX‐X/R@F@Ag three‐layer EM shielding composite film provides structural design and research ideas for the application of the new MXenes material in EM shielding composites.Highlights The addition of Ti3C2Tx MXene will generate more conductive network nodules A complete 3D conductive network is constructed in the membrane This paper discusses the influence of Ti3C2Tx MXene on EM shielding Multiple internal reflections of EMW between Ti3C2Tx MXene 2D nanosheets The EM shielding mechanism of the film is discussed from the angle of 3D

A comprehensive review of radiation shielding concrete: Properties, design, evaluation, and applications

AbstractThis review paper provides a comprehensive analysis of radiation shielding concrete, covering its properties, design, evaluation, and applications. It begins with an introduction, stating the objective and scope. The paper explores radiation shielding basics, including ionizing radiation, shielding principles, and materials used for shielding. Concrete's properties relevant to shielding, radiation attenuation mechanisms, and factors affecting its efficiency are discussed. Different types of radiation shielding concrete are examined, along with their applications. The design and formulation of shielding concrete, including mix proportions, optimization techniques, and quality control, are presented. Evaluation methods and standards are discussed. Lastly, challenges, future directions, and emerging technologies are outlined. This review paper serves as a valuable resource for professionals involved in radiation shielding. The review on radiation shielding concrete highlighted its effectiveness in attenuating ionizing radiation, emphasizing material composition, density, and thickness as key design factors. Evaluation methods, such as gamma spectroscopy and Monte Carlo simulations, are discussed, demonstrating its versatile applications in nuclear facilities, healthcare, and space exploration.

Electromagnetic Interference Shielding Films: Structure Design and Prospects.

The popularity of portable and wearable flexible electronic devices, coupled with the rapid advancements in military field, requires electromagnetic interference (EMI) shielding materials with lightweight, thin, and flexible characteristics, which are incomparable for traditional EMI shielding materials. The film materials can fulfill the above requirements, making them among the most promising EMI shielding materials for next-generation electronic devices. Meticulously controlling structure of composite film materials while optimizing the electromagnetic parameters of the constructed components can effectively dissipate and transform electromagnetic wave energy. Herein, the review systematically outlines high-performance EMI shielding composite films through structural design strategies, including homogeneous structure, layered structure, and porous structure. The attenuation mechanism of EMI shielding materials and the evaluation (Schelkunoff theory and calculation theory) of EMI shielding performance are introduced in detail. Moreover, the effect of structure attributes and electromagnetic properties of composite films on the EMI shielding performance is analyzed, while summarizing design criteria and elucidating the relevant EMI shielding mechanism. Finally, the future challenges and potential application prospects of EMI shielding composite films are prospected. This review provides crucial guidance for the construction of advanced EMI shielding films tailored for highly customized and personalized electronic devices in the future.

Application Practice of SHPB Experimental Technology in "Blasting Engineering" Teaching

The course of "Blasting Engineering" is a highly practical professional course in the field of civil engineering. In order to help students deeply understand and comprehend the propagation and attenuation mechanism of stress waves during rock blasting process, as well as the influence of rock dynamic characteristics on blasting rupture effect, SHPB impact compression experimental technology is introduced into the teaching of "blasting engineering". Firstly, the structure, experimental process, and principles of SHPB equipment were introduced, allowing students to have a better understanding of the experimental principles of SHPB and the theoretical calculation methods of rock dynamic parameters. Then, by combining SHPB experiments with the theoretical course of "Blasting Engineering", the teaching mode can solve students' difficulties in learning blasting theory, exercise their scientific research and exploration abilities, expand their innovative thinking, and cultivate their ability to propose and solve key scientific problems. This helps to unleash students' subjective initiative in conducting experimental research independently and improve teaching effectiveness.

Numerical investigation of serration angle on trailing edge noise reduction

The influence of serration angle on the three-dimensional flow characteristics and noise attenuation mechanisms of a NACA6512-63 airfoil is explored in this research using large eddy simulation (LES) and spectral proper orthogonal decomposition (SPOD) methods. Analysis of the mean flow field reveals the formation of counter-rotating vortex pairs, resulting from the outward flow towards the serration edges and the downwash flow in the valleys. This flow modification alters the effective angle of the serration, which in turn impacts its noise reduction performance. Furthermore, the noise reduction mechanism is investigated by comparing the general solution of Lyu's semi-analytical equation with the SPOD mode results, and the frequency range associated with noise attenuation is analyzed. The findings indicate that the case with λ/h=0.15 demonstrates the most significant noise reduction effect. This research offers valuable insights into the interplay between serration geometry and the resulting flow characteristics and noise reduction mechanisms.

Synthesis and high electromagnetic wave absorption performance of carbon-enriched porous SiOC ceramics

The carbon-enriched porous SiOC ceramics with enhanced electromagnetic wave (EMW) absorption properties were synthesized through the hydrothermal method followed by a polymer-derived ceramics (PDCs) process. As the annealing temperature rises from 1200 °C to 1500 ℃, SiC and SiO2 crystals are gradually separated from the porous amorphous SiOC matrix, and the degree of graphitization of free carbon increases. The porous SiOC ceramics annealed at 1400 °C exhibit the presence of SiC, SiO2, turbostratic graphite, and amorphous SiOC phases, which significantly impact the impedance matching and attenuation constant of the material. The minimum reflection loss (RLmin) value of the SiOC ceramics reaches −67.98dB with a matching thickness of 3.19mm and the effective absorption bandwidth (EAB) is 4.45GHz at 1.39mm. The carbon-enriched porous SiOC ceramics with strong absorption capacity and wide absorption bandwidth are primarily owing to appropriate impedance matching and multiple attenuation mechanisms, such as conduction loss, interfacial polarization, and defect-induced polarization, indicating that the SiOC ceramics exhibit significant potential as a high-performance EMW absorbing material.

Overload of dissolved organic matter (DOM) in riparian infiltration zone increasing the pollution risk of naphthalene, insight from the competitive inhibition of naphthalene biodegradation by DOM.

Riparian infiltration zones are crucial for maintaining water quality by reducing the aqueous concentrations of polycyclic aromatic hydrocarbons (PAHs) through adsorption and biodegradation within the aquatic ecosystem. Dissolved organic matter (DOM) are ubiquitous in riparian infiltration zones where they extensively engage in the adsorption and biodegradation of PAHs, thereby influencing PAHs natural attenuation potential within riparian infiltration zones. Few studies have explored the natural attenuation mechanisms of PAHs influenced by DOM in riparian infiltration zones. In this study, the natural attenuation mechanisms of naphthalene (a typical PAHs component), under the influence of DOM, were explored, based on a case riverside source area. Analysis of microbial community structures, and the electron acceptor (e.g., Fe(III), DO/NO3-, SO42-)/electron donor (naphthalene and DOM) concentration changes within the riparian infiltration zone revealed a competitive inhibition relationship between DOM and naphthalene during microbial metabolism. Biodegradation experiments showed that when the concentration of DOM is higher than 4.0 mg·L-1, it inhibits the biodegradation of naphthalene. DOM competitively inhibits the biodegradation of naphthalene through the following mechanisms: (i) triggering microbial antioxidative defense mechanisms, diminishing the available resources for microbial participation in naphthalene degradation; (ii) altering microbial community structure; (iii) modulating microbial EPS composition, reducing the efficiency of microorganisms in utilizing carbon sources; and (iv) inhibiting the expression levels of downstream genes involved in naphthalene degradation. The competitive inhibition constants of DOM with concentrations of 1.0, 2.0, 4.0, 8.0, and 16.0 mg·L-1 on naphthalene biodegradation are -2.0 × 10-3, -5.0 × 10-3,1.0 × 10-3, 4.0 × 10-4, and 1.0 × 10-4, respectively. These findings enhance understanding of PAHs attenuation in riparian infiltration zone, providing a basis for assessing and managing PAHs pollution risks during riparian extraction.

Hydrodynamic performance on cavity resonant type floating breakwater for long waves

Abstract The current work investigates a cavity resonant-type floating breakwater (FB). Therefore, the Helmholtz resonator principle was adopted to reduce the intensity of long-period waves effectively. The configuration of the internal cavity was optimized to resonate with the fluid inside the cavity, thereby dissipating wave energy. Five models with different gap distances (GDs) were analyzed. Various experiments compared the traditional box-type floating breakwater performance with modified floating breakwater models. The experiments were focused on evaluating the transmission coefficient of stationary models under various wave heights and periods. According to the results, the optimized wave attenuation mechanism can effectively overcome the technical defects of the conventional floating breakwater, which limits its application for long-period wave attenuation. Meanwhile, it is found that for a given principal size, the proposed floating breakwater exhibits a 20%-30% smaller transmission coefficient relative to the traditional box-type FB in medium and long-period waves.

Sonic P-wave attenuation based on fluid pressure differential between joint and matrix

When P-wave compresses in-situ rocks saturated with fluid, there is a fluid pressure differential between compliant joints and stiff matrix. The pressure differential automatically drives a mesoscale squirt between joint wall and matrix interior. This mechanism is likely to dominate sonic P-wave attenuation in the field. A new model of P-wave attenuation based on the mesoscale squirt is established, in which the first porosity is represented by matrix pores while the second porosity is represented by joint. Sonic log of a sandstone reservoir in Saudi Arabia is used to illustrate the model. Both estimated phase velocity and measured quality factor of sonic P-wave are accurately simulated. The results show that for the sandstone reservoir, the relative second porosity is 5%, inter-joint distance is 0.1 m, squirt permeability at very low frequencies is about half of Darcy permeability of the matrix, and joint gap is 800 μm (quadruple grain diameter of 200 μm). Surprisingly, the model of joint-matrix squirt is also capable of reproducing seismic P-wave attenuation measured in the shallow crust of southern California. Therefore, mesoscale squirt across the joint wall is probably the underlying mechanism of attenuation for sonic and seismic P-waves shallower than 10 km.

Plant Phytochrome Interactions Decode Light and Temperature Signals.

Plant phytochromes perceive red and far-red light to elicit adaptations to the changing environment. Downstream physiological responses revolve around red-light-induced interactions with phytochrome-interacting factors (PIF). Phytochromes double as thermoreceptors, owing to the pronounced temperature dependence of thermal reversion from the light-adapted Pfr to the dark-adapted Pr state. Here, we assess whether thermoreception may extend to the phytochrome:PIF interactions. While the association between Arabidopsis (Arabidopsis thaliana) PHYTOCHROME B (PhyB) and several PHYTOCHROME-INTERACTING FACTOR (PIF) variants moderately accelerates with temperature, the dissociation does more so, thus causing net destabilization of the phytochrome:PIF complex. Markedly different temperature profiles of PIF3 and PIF6 might underlie stratified temperature responses in plants. Accidentally, we identify a photoreception mechanism under strong continuous light, where the extent of phytochrome:PIF complexation decreases with red-light intensity rather than increases. Mathematical modeling rationalizes this attenuation mechanism and ties it to rapid red-light-driven Pr⇄Pfr interconversion and complex dissociation out of Pr. Varying phytochrome abundance, e.g., during diurnal and developmental cycles, and interaction dynamics, e.g., across different PIFs, modify the nature and extent of attenuation, thus permitting light-response profiles more malleable than possible for the phytochrome Pr⇄Pfr interconversion alone. Our data and analyses reveal a photoreception mechanism with implications for plant physiology, optogenetics, and biotechnological applications.

Broadband surface wave manipulation by periodic barriers in unsaturated soil.

Periodic wave barriers have been widely used to manipulate elastic waves propagating in saturated and single-phase soil due to their attenuation zone properties. However, it is difficult to promote application of periodic barriers in unsaturated soils due to their complex constitutive relationship. In this study, manipulation of surface waves by periodic in-filled trench barriers in unsaturated soil has been studied based on the periodic theory. The dispersion relations of a periodic structure for surface waves in unsaturated soil are determined. The attenuation mechanism of evanescent surface waves is revealed. Next, the effects of several key parameters of unsaturated soil on the attenuation zones of the periodic in-filled trench barriers are comprehensively discussed. It is found that in a particular range for material parameter, the surface waves are attenuated over the entire frequency range due to the viscosity of fluid. Finally, a periodic in-filled trench barrier is designed according to a field test of ground vibration induced by a train, and its performances in mitigating surface waves propagating in unsaturated and saturated soils are conducted and compared by conducting analysis in time domain. This investigation provides a new insight for manipulating surface waves by periodic barriers. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 1)'.

Evaluation of the attenuation mechanism of the noise reduction performance of polyurethane porous elastic road surface

The polyurethane porous elastic road surface (PERS) demonstrates superior noise reduction performance, primarily due to its porous structure that facilitates effective sound absorption and its high elasticity that contributes to substantial vibration attenuation. However, it is susceptible to void clogging and long-term aging during service, leading to a gradual decline in noise reduction performance. To investigate the attenuation characteristics of noise reduction performance in PERS mixtures under void clogging and long-term aging conditions, this study investigated PERS mixtures subjected to various clogging cycles and aging times. Concurrently, the tire vertical drop test and standing wave tube absorption coefficient test were employed to analyze the variation rule in the noise sound pressure level (SPL) and sound absorption coefficient frequency curves under the above conditions. The results show that the noise reduction performance of the PERS mixture exhibits a variation rule of first decreasing and then increasing with the increase of the clogging cycles, and the required clogging amount to reach the void saturation state is 30–40 g. Compared to before clogging, the PERS mixture after clogging has an enhanced ability to absorb low-frequency noise and a weakened ability to absorb high-frequency noise; the sizes of the cloggings have a higher degree of attenuation in low-frequency sound absorption than in high-frequency. As long-term aging progresses, the noise reduction performance of the PERS mixture first increases and then decreases. Notably, long-term aging predominantly impacts the high-frequency noise reduction capabilities of the PERS mixture. The impact of void clogging on the noise reduction performance of PERS mixtures is found to be more pronounced than that of long-term aging.

Three-dimensional n-MoSe2/GOx (n= 1T, 1T' and 2H) microsphere: Phase-modulation strategy and microwave absorbing mechanism

MoSe2 was identified as a potential microwave absorber, whereas its practical application was predominantly affected by the ambiguous electromagnetic wave attenuation mechanism and dielectric properties. Here, we developed a novel phase assembly-modulating strategy to prepare n-MoSe2/GOx (n = 1T, 1T' and 2H) composites, wherein phase modulation of MoSe2 exerted a gainful effect on microwave absorption properties. The unique 1T′-MoSe2 phase was first explored in microwave absorption and composited with GOx to afford advanced conductivity loss and dielectric loss. The introduction of additional interface (2H/1T or 2H/1T') and abundant unsaturated defects promote multiple polarization, the semiconductor-metal mixed phase brought in a certain magnetic loss, optimizes the electron transfer ability and adjusts the impedance matching. Consequently, 1T′-MoSe2/GOx provides the minimum reflection loss (RLmin) of −52.08 dB and the effective absorption bandwidth (EAB, RL < -10 dB) of 5.3 GHz at 10 % filler content, which is approximately 9 times that of 2H–MoSe2/GOx and nearly 5 times that of 1T-MoSe2/GOx. This paper specifically explains the reasons for the phase modulation-induced magnetic losses and provides an effective phase modulation paradigm for developing advanced transition metal disulfide (such as MoS2, WS2 and WSe2) microwave absorbers.

Study on Attenuation Mechanism and Durability Improvement of Platinum-Carbon Catalysts for Proton Exchange Membrane Fuel Cells

The relationship between Pt particle size and activity and durability of Pt/C electrocatalysts on rotating disk electrodes is established and the results show that Pt/C electrocatalysts with particle size over 3.5 nm have excellent resistance to Pt particle decay and carbon corrosion. Further, the research results on the mechanism of Pt particle decay and carbon corrosion show that the Pt particle attenuation is composed of 80% Ostwald ripening and 20% particle agglomeration, and the carbon corrosion is affected by the catalytic action of Pt particles. Therefore, the above results show that regulating the Pt particle size to 3.5–4.0 nm can improve the durability of Pt/C electrocatalysts on RDE. To verify the accuracy of this conclusion and determine the optimal particle size range in practical application, single cells with 5 × 5 cm2 is assembled to evaluate the performance and durability of cathode Pt/C electrocatalysts under H2/air. The results show that cathode Pt/C electrocatalysts with particle size between 3.5 nm and 3.8 nm have high single cell performance (2.3 A cm−2@0.65 V) and durability (A loss of 15 mV@0.8 A cm−2 after 30000 cycles). These findings reveal the attenuation mechanism of Pt/C electrocatalysts and provide ideas for the development of high-durability Pt-based electrocatalysts for practical applications.

Migration and natural attenuation of leachate pollutants in bedrock fissure aquifer at a valley landfill site

Groundwater pollution from valley type landfills is concerning, and natural attenuation by contaminants is increasingly relied upon. However, the reliability of natural attenuation in such complex sites has been called into question due to incomplete understanding of their attenuation mechanisms. Therefore, we conducted field investigations, monitoring analyses, mathematical statistics, and machine learning techniques to elucidate the natural attenuation mechanisms of pollutants within bedrock fissures at a prototypical valley type landfill located in the east Yanshan Mountains, China. Our results indicate that 50% of the monitored indicators showed extreme pollution in bedrock fissure aquifers, due to seepage from the valley type landfill site. Ammonia nitrogen, arsenic, cadmium, lead, iron, manganese, and mercury were among the contaminants that could pose serious risks to human health. Pollutant concentrations in bedrock fissure aquifers were lower during the rainy season compared to the dry season as the aquifer was rapidly recharged by strong rainfall runoff. The initial concentration of bedrock fissure water generally increased during the flow through the landfill. However, significant natural attenuation of total dissolved solids, oxygen consumption, ammonia, cadmium, and lead occurred after passing through the landfill (p<0.05), with attenuation coefficients of 0.0041 m-1, 2.56×E-5m-2, 4.18×E-5m-2、0.0015 m-0.99, and 6.83×E-33m-12.49, respectively. The driving mechanisms for natural attenuation include physical migration, leaching, microbiological degradation, and adsorption, primarily occurring within 600-650 m downstream of the landfill boundary. This study makes fundamental contribution to the understanding of the migration and natural attenuation process of leachate pollutants in bedrock fissure aquifer, which will provide a scientific basis for implementation of natural attenuation strategies in complex site remediation. Future research should examine more precise evidence of natural attenuation feasibility in complex sites in conjunction with monitoring networks.