In this study, we investigated the oxidative mechanisms of nano zero-valent iron (nZVI) enhanced potassium ferrate (K2FeO4), focusing on tributyltin (TBT) and triphenyltin (TPhT) as target pollutants. The addition of nZVI enhanced the degradation of both organic tin compounds by K2FeO4, exhibiting pseudo-first-order kinetics influenced by pH, carbonate, and fulvic acid. nZVI, as a reducing agent, facilitated the generation of stronger oxidizing species Fe (V) and Fe (IV) from K2FeO4 through electron transfer. The presence of hydroxyl radicals (OH) was confirmed by tert-butyl alcohol (TBA) verification. Intermediate products of TBT degradation by nZVI-enhanced K2FeO4 were identified using GC-MS, confirming de-alkylation leading to stepwise oxidation to inorganic tin ions. Due to excessively long Sn-C bonds in diphenyltin, rendering them unstable, Density Functional Theory (DFT) calculations were employed. Results indicated that Fe (IV) and Fe (V) predominantly attacked the Sn-C bonds of TPhT, while OH primarily targeted the benzene ring. HOMO energy levels suggested that Fe (V) was more prone to oxidizing TPhT than Fe (IV). Gibbs free energy calculations demonstrated that, in the presence of Fe (IV) and Fe (V), the energy barrier for breaking bonds and oxidizing into inorganic tin ions decreased, favoring the process over the self-decomposition of TPhT. Additionally, the lower energy barrier for OH indicated an easier degradation of TPhT. This study reveals that nZVI-enhanced K2FeO4 effectively removes TBT and TPhT, contributing to the understanding of the ferrate-mediated degradation mechanism of organic tin compounds. The findings offer insights and theoretical guidance for remediating organic tin pollution in aquatic environments.

The identification and quantification of soil heavy metal (HM) pollution sources and the identification of driving factors is a prerequisite of soil pollution control. In this paper, the Sabaochaqu Basin of the Tuotuo River, located in the Tibetan Plateau and the headwater of the Yangtze River, was selected as the study area. The soil pollution was evaluated using geochemical baseline, and the source apportionment of soil HMs was performed using absolute principal component score-multiple linear regression (APCS-MLR), edge analysis (UNMIX) and positive matrix decomposition (PMF). The driver of the source factor was identified with the geodetector method (GDM). The results of pollution evaluation showed that the HM pollution of soil in the study area was relatively light. By comparison, UNMIX model was considered to be the preferred model for soil HMs quantitative distribution in this study area, followed by PMF model. The UNMIX model results show that source 1 (U-S1) was dominated by As, with a contribution rate of 53.31%; source 2 (U-S2) was dominated by Cd and Zn, whose contribution rates are 50.35% and 46.60% respectively; source 3 (U-S3) was dominated by Pb, with a contribution rate of 45.58%; source 4 (U-S4) was dominated by Cr, Cu, Hg and Ni, with contribution rates of 60.58%, 60.07%, 51.58% and 56.45%, respectively. The GDM results showed that the main driving factors of U-S1 were distance from lake (explanatory power q = 0.328) and distance from wind channel (q = 0.168), which were defined as long-distance migration sources. The main driving factors of U-S2 were parent material type (q = 0.269) and distance from Tuotuo river (q = 0.213), which were defined as freeze-thaw sources. The main driving factors of U-S3 were distance from town (q = 0.255) and distance from county road (Yanya Line) (q = 0.221), which were defined as human activity sources. The main drivers of U-S4 were V (q = 0.346) and Sc (q = 0.323), which were defined as natural sources. The GDM results of the 3 models were generally consistent with the analytical results of similar types of sources, especially the results of PMF model and Unmix model can basically verify each other. The research results can provide important theoretical reference for the analysis of HM sources in the soil of high-cold and high-altitude regions.

The pollution of water bodies by eutrophication not only poses a serious threat to the ecological security of water bodies in China but also has a severe impact on the urban environment and the quality and image of the city and has become one of the urgent problems to be addressed in global water pollution control. In the case of conventional methods to control eutrophication with little success, ecological combinations of technologies have become a current research hotspot. This thesis will take typical cyanobacteria, Microcystis aeruginosa, as the research object, a micro-aeration system, activated carbon fiber, and white rot fungi for effective coupling research into a micro-aeration bio-carbon fiber enhanced treatment of eutrophication of water bodies using new methods. The implementation of the project will develop a set of innovative technologies for microbial ecological management of eutrophic water bodies that can provide new ideas for improving the city’s cityscape, upgrading the city’s image, and improving the quality of the urban water environment. It will also provide technical support for creating a beautiful place with beautiful mountains and clear water in our city and for constructing an ecological barrier on the upper reaches of the Yangtze River.

The conventional two dimensional (2D) inverse synthetic aperture radar (ISAR) imaging fails to provide the targets' three dimensional (3D) information. In this paper, a 3D ISAR imaging method for the space target is proposed based on mutli-orbit observation data and an improved orthogonal matching pursuit (OMP) algorithm. Firstly, the 3D scattered field data is converted into a set of 2D matrix by stacking slices of the 3D data along the elevation direction dimension. Then, an improved OMP algorithm is applied to recover the space target's amplitude information via the 2D matrix data. Finally, scattering centers can be reconstructed with specific three dimensional locations. Numerical simulations are provided to demonstrate the effectiveness and superiority of the proposed 3D imaging method.

Abstract In order to explore the spatio-temporal evolution law of surface heat flux during the urbanization process in new mountainous development city, the spatio-temporal evolution law of heat balance process of different land use types and heat flux process before, during and after urbanization in Yuelai New City were analyzed by satellite remote sensing image data and SEBAL model, the effect of land use/vegetation cover on surface heat flux was also discussed. The results include (1) the net radiation flux and difference of various land use types in Yuelai New City reached the maximum in July and the minimum in January, vegetation coverage was one of the factors affected sensible heat flux of different land use types. The order of latent heat flux was woodland > farmland > bare land > residential land, and the order of soil heat flux was bare land > residential land > woodland > farmland. (2)The urbanization process increased the area of low net radiation value in Yuelai New City, and sensible heat flux showed an increasing trend and accounted for the largest proportion in the energy output. The low value area of latent heat flux gradually expanded to the north and south. Soil heat flux and sensible heat flux were higher in the area with low latent heat flux. The distribution rules of soil heat flux and sensible heat were basically consistent, and both showed an increasing trend. (3)The correlation between soil heat flux and land use area was the best among the energy output factors. Fractional vegetation cover( FVC ) had a greater impact on heat fluxes than land use area. Residential combined land was most closely related to FVC , and latent heat flux was most affected by FVC .

The adverse effects of microplastics ingested by aquatic organisms have been reported previously. However, most studies are primarily qualitative; therefore, it is challenging to determine the direct interactions between microplastics and organisms. In this study, for the first time, the microplastic intake behavior of silver carp (Hypophthalmichthys molitrix) larvae, a popular fish in China, as well as intestine accumulation and excretion of the microplastics were quantitatively investigated. The results showed that the intake of microplastics by silver carp larvae was negatively correlated with the particle size of microplastics but positively correlated with the exposure concentration. After intaking microplastics of different sizes, small-sized microplastics (≤ 150 μm) were rapidly excreted from the intestine of silver carp, whereas some large-sized microplastics (≥ 300 μm) remained in the intestine for a long time. The presence of food significantly increased the intake of large-sized microplastics, while small-sized microplastics intake was unaffected by the food. More importantly, the ingested microplastics caused specific changes in the diversity of intestinal microflora, potentially leading to abnormal immune and metabolic functions. The results of this study provide a new understanding on the potential impacts of microplastics on aquatic organisms.

Microplastics (MPs) are receiving increasing attention from researchers. They are environmental pollutants that do not degrade easily, are retained for prolonged periods in environmental media such as water and sediments, and are known to accumulate in aquatic organisms. The aim of this review is to show and discuss the transport and effects of microplastics in the environment. We systematically and critically review 91 articles in the field of sources, distribution, and environmental behavior of microplastics. We conclude that the spread of plastic pollution is related to a myriad of processes and that both primary and secondary MPs are prevalent in the environment. Rivers have been indicated as major pathways for the transport of MPs from terrestrial areas into the ocean, and atmospheric circulation may be an important avenue for transporting MPs between environmental compartments. Additionally, the vector effect of MPs can change the original environmental behavior of other pollutants, leading to severe compound toxicity. Further in-depth studies on the distribution and chemical and biological interactions of MPs are highly suggested to improve our understanding of how MPs behave in the environment.

水资源合理利用、水生态环境保护的平衡发展已成为当今社会经济发展亟待解决的关键性问题.文章以四川省绵阳市为例,深入 51 个乡镇、园区、企业实地调研并分析了该市在"5.12 汶川地震"后近 15 年来其所在的涪江中上游流域在社会经济发展过程中水资源利用和水环境保护存在的主要问题,并对此提出了解决问题的对策建议,为汶川地震后绵阳市制定水资源利用和水环境保护可持续发展政策提供了科学依据,为其他河流流域水资源合理利用、水生态保护治理提供了重要的借鉴与参考案例.

为评价重庆万州龙宝河片区海绵城市改造的径流污染控制效果,运用 SWMM模型模拟该片区的径流过程,研究不同重现期下绿色屋顶、透水铺装、生物滞留带等低影响开发(LID)设施对污染物的控制效果.结果表明:当重现期为 1～50 a 时,LID设施对悬浮固体(SS)、化学需氧量(COD)、总磷(TP)、总氮(TN)的总量削减率分别可达 47％～72％、56％～70％、48％～64％、43％～66％;对上述污染物峰值浓度的削减率分别为 31.31％～41.05％、25.12％～38.93％、22.50％～31.38％、13.39％～21.76％,并能延迟峰现时间 2～11 min.由此可见,海绵城市改造能够有效缓解径流污染,但随着重现期增加,控制效果会变差,说明海绵城市更适用于低降雨强度的径流污染控制.

The behavior of microplastics (MPs) as vectors of environmental contaminants in aquatic systems can change the fate and transport of some toxic substances and promote their diffusion and bioenrichment. Therefore, our study investigated the adsorption of two kinds of metal ions [Pb(II) and Cd(II)] by polypropylene (PP) and polystyrene (PS) in aqueous solution and the desorption of metal ions in the gastrointestinal environment. Our findings indicated that pH, humic acid, and particle size are key factors affecting the adsorption of metal ions on MPs. The adsorption capacity of Pb(II) and Cd(II) on MPs increases as pH increases, and the presence of humic acid significantly inhibits the adsorption of metal ions on MPs. In a simulated gastrointestinal environment, the desorption rates of the two metal ions on MPs were high and controlled by the MP particle size, suggesting a possible toxicological risk for organisms after ingestion of metal-contaminated microplastics.

Compared with traditional sparsity-driven methods, inverse synthetic aperture radar (ISAR) image enhancement method based on convolutional neural networks (CNNs) have outstanding performance in recent research, which improved the resolution of reconstructed image significantly with higher imaging efficiency. However, recently developed ISAR image enhancement methods based on neural networks are only effective in the same scenarios where the training data was generated. Additionally, all these method adopted the mean-squared error as the loss function, causing the reconstructed ISAR image to lose high-frequency information and fail to capture appropriate details. To address these limitations, a single ISAR image enhancement framework based on a modified super-resolution convolutional neural network (SRCNN) is proposed in this paper. The ISAR image enhancement processing framework were improved to minimize the influence of the fixed imaging model. A combined loss function, composed of the structural similarity (SSIM) loss and the L1 loss functions, was adopted in the proposed framework to retain the high-frequency information and the luminance information of the ISAR image, while improving the resolution. Through quantitative analysis of experimental results by using different quality evaluation indicators, it demonstrated that compared with extant methods, the proposed framework provides reconstructed ISAR images with higher resolution and definition over a range of different scenarios.

综述了环境因素对微塑料性质的影响,讨论了微塑料对典型污染物的吸附行为,并对微塑料与污染物之间的吸附机理进行了探讨.微塑料的疏水性和粒径是原始塑料碎片吸附的主要影响因素,而对于老化的微塑料,氢键、亲水性和比表面积的增加会影响吸附行为.盐度和pH的影响总是通过改变微塑料和污染物的带电状态来影响吸附条件,从而引起竞争性吸附.这对于评估微塑料对从人类到整个环境的生物体所构成的潜在风险至关重要,并为今后微塑料对环境污染物的吸附富集行为研究提供理论依据.

Phosphorus (P) is one of the main substances to induce the eutrophication of water. The occurrence and migration of P in water are largely affected by the sediment. Although some studies have investigated the adsorption/desorption characteristics of phosphorus by the sediment, how the change of turbulence intensity affects the sediment flocculation and thus changes the desorption characteristics of P is still unknown. Herein, a nearly turbulent multilayer grid vibration device was designed and built to study the desorption characteristics of P by the sediment under different turbulent conditions. Furthermore, the movement and variation of particle size of the sediment that occurred in the event of turbulence have been investigated based on the images collected by the image collection device. The result shows that the secondary pollution to reservoir water may be induced by the sediment in the Three Gorges Reservoir deteriorating the eutrophication in the Reservoir. The desorption flux of P will augment with the enhancing water turbulence, sediment concentration and water temperature, where the turbulent diffusion influences the desorption of P from the sediment significantly. With the increasing intensity of turbulence, more bottom sediment will be incipiently moved and suspended which will impel the desorption of P more obviously. As the intensity amplifies further, the median diameter of the sediment tends to ascend first and then descend, and the variation of particle size caused by the flocculation and deflocculation of the sediment will affect the desorption of P to some degree. However, the dominant factor for the desorption of P is still the hydrodynamic condition, that is, the desorption of P elevates the increasing intensity of turbulence.

We proposed a self-referenced technique for measuring the spatiotemporal characteristics of ultrashort pulses using the coherent diffraction imaging. This technique includes the wavelength spatial multiplexing coherent diffraction imaging measurement and the three-dimensional spatiotemporal amplitude and phase reconstruction. In experiment, we verified the feasibility of this technique by measuring a pulse from the femtosecond laser oscillator. Wavelength spatial multiplexing was realized by the combination of two-dimensional diffracted optical element and narrow-band-pass filter, and the amplitude and phase information of each wavelength was recovered by ePIE (extended Ptychographic Iterative Engine) algorithm. This technique can measure the three-dimensional spatiotemporal amplitude and phase information of ultrashort pulses with high resolution and simplicity. In the future, it is expected to be an effective method for the comprehensive monitoring of the spatiotemporal optical field of ultrashort pulse lasers, and will be helpful for the laser performance improvement.

利用CNKI《中国期刊全文数据库》,对2008年至2018年收录的相关文献从年度发文量、主要发文机构、被引频次与下载量等方面进行计量分析,并与WebofScience数据库该领域的研究成果进行对比分析.结果表明:统计范围内的相关文献发文总量先上升后下降,发文数量最多的期刊为《环境科学与技术》和《环境科学学报》,中国科学院生态环境研究中心的发文量、综合影响力比较高,统计范围内的文献下载次数虽然多,但是篇均被引次数较低."生态风险评价"、"沉积物"、"潜在生态风险"、"植物修复"等研究方向受关注度较高.

Small perturbations and strong impurity exhaust capability associated with the small grassy ELMs render the grassy-ELM regime a suitable candidate for achieving steady-state H-mode operation with a radiative divertor, especially in a metal-wall device, such as the Experimental Advanced Superconducting Tokamak (EAST). As the degradation of pedestal performance with excessive divertor impurity seeding or accumulation tends to be accompanied with significantly increased radiation near the divertor X point, feedback control of the absolute extreme ultraviolet (AXUV) radiation near the X point has been employed to maintain the confinement property in EAST. However, the absolute value of the AXUV radiation at the outer target varies with plasma conditions as during the divertor detachment process. Thus, a new feedback-control scheme has been recently developed and applied to grassy-ELM H-mode plasmas in EAST to achieve stationary partial detachment while maintaining good global energy confinement with H 98,y2 >1. In this scheme, electron temperatures (T et) measured by divertor Langmuir probes are used to identify the onset of detachment, and then the plasma control system (PCS) switches to the feedback control of one channel of AXUV radiation near the X point, where a steep gradient in the radiation profile is present. The feedback is performed through pulse-width-modulated duty cycle of a piezo valve to seed impurities with mixed gas (50% Ne and 50% D2) from the outer target plate near the strike point in the upper tungsten monoblock divertor. T et near the strike point is maintained in the range of 5–8 eV, and peak surface temperature on the outer target plate (T IR,peak) is suppressed and maintained at ∼180 °C, based on infrared camera measurements. The plasma stored energy maintains nearly constant over the entire feedback-control period. It thus offers a highly promising plasma control scenario suitable for long-pulse high-performance H-mode operation in EAST, which is potentially applicable to future steady-state fusion reactors as an integrated solution for the control of both ELM-induced transient and steady-state divertor heat loads while maintaining good core confinement.

Cross-range scaling of sequential inverse synthetic aperture radar (ISAR) images is a vital problem for the three-dimensional (3D) reconstruction of spatial targets. Specifically, since the angular velocity of spatial targets cannot be accurately estimated due to their non-cooperative nature, the obtained cross-range coordinates of the scattering points often have non-negligible errors. The errors may result in a serious distortion of the reconstructed geometry of the targets, which makes consequent target recognition and classification unreliable. To tackle this problem, via geometrical analysis, the relationship between the cross-range projection vector and the range projection vector is revealed for the first time, based on which a novel algorithm is proposed to iteratively scale the cross-range coordinates with no need for estimating the angular velocity of the spatial targets. Experimental simulations show that the proposed algorithm not only provides a higher accuracy of 3D reconstruction, but also has a lower computational complexity compared with conventional algorithm.

The development of the urban Binjiang belt has influenced the water environment quality. Taking the Chongqing section of the Yangtze River basin and the Binjiang section of the urban center as examples, representative water intake points were selected to extract the urban layout pattern of the Binjiang belt, and the distribution characteristics of its influence on water environment quality were studied using a geographic information system. A structural equation model was used to establish a model of the influence of urban layout on water environment quality, and the water quality test results were added to the model to calculate the contribution rates of different land types to water environment quality. The research results and methods can be used for reference for urban water environment quality and for evaluating the influence of urban design on water environment quality.

Conversion of perfluoroalkyl acid (PFAA) precursors in the environment has been a hotspot research in recent years. This study firstly determined the spatial distribution of PFAAs and their precursors including 8:2 fluorotelomer unsaturated acid (8:2 FTUCA), perfluorooctane sulfoneamide (FOSA), and diperfluorooctane sulfonamido ethanol-based phosphate (di-SAmPAP), then investigated the conversion of the potential precursors in the seawater and sewage treatment plants (STPs) effluents. The results indicated that the target pollutants showed a typical concentration gradient from nearshore to offshore. And the obviously increased concentration of perfluorinated carboxylic acids (△[PFCAs]) after oxidation treatment can verify the existence of PFAA precursors in the seawater and STP effluents. The concentrations of PFCAs with carbon atom numbers 4-9 (PFCAC4-C9) revealed the most increase. Moreover, the levels of △[PFCAs] and the ratios of △[PFCAs] to their concentration before oxidation (△[PFCA]/[PFCA]before oxidation) indicated obvious spatial variations in the seawater and STP effluents. The higher levels of △[PFCAC4-C12] and the lower ratios of ∑△[PFCAC4-C12]/∑[PFAA]before oxidation were observed in the STP effluents, which implied that precursors might be decomposed during the sewage treatment process. These results suggested the STP effluents might have an important effect on the PFAAs levels of seawater.