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In the wake of frequent and intensive human activities, highly urbanized areas consistently grapple with severe water environmental challenges. It becomes imperative to establish corresponding water environment models for simulating and forecasting regional water quality, addressing the associated environmental risks. The distributed framework water environment modeling system (DF-WEMS) incorporates fundamental principles, including the distributed concept and node concentration mass conservation. It adeptly merges point source and non-point source pollution load models with zero-dimensional, one-dimensional, and two-dimensional water quality models. This integration is specifically tailored for various Hydrological Feature Units (HFUs), encompassing lakes, reservoirs, floodplains, paddy fields, plain rivers, and hydraulic engineering structures. This holistic model enables the simulation and prediction of the water environment conditions within the watershed. In the Taihu Lake basin of China, a highly urbanized region featuring numerous rivers, lakes and gates, the DF-WEMS is meticulously constructed, calibrated, and validated based on 26 key water quality monitoring stations. The results indicate a strong alignment between the simulation of water quality indicators (WQIs) and real-world conditions, demonstrating the model's reliability. This model proves applicable to the simulation, prediction, planning, and management of the water environment within the highly urbanized watershed. [ABSTRACT FROM AUTHOR]

As an advanced driver assistance system, automatic emergency braking (AEB) can effectively reduce accidents by using high-precision and high-coverage sensors. In particular, it has a significant advantage in reducing front-end collisions and rear-end accidents. Unfortunately, avoiding side collisions is a challenging problem for AEB. To tackle these challenges, we propose active seat belt pretensioning on driver injury in vehicles equipped with AEB in unavoidable side crashes. Firstly, records of impact cases from China's National Automobile Accident In-Depth Investigation System were used to investigate a scenario in which a vehicle is impacted by an oncoming car after the vehicle's AEB system is triggered. The scenario was created using PreScan software. Then, the simulated vehicles in the side impact were devised using a finite element model of the Toyota Yaris and a moving barrier. These were constructed in HyperMesh software along with models of the driver's side seatbelt, side airbag, and side curtain airbag. Moreover, the models were verified, and driver out-of-position instances and injuries were evaluated in simulations with different AEB intensities up to 0.7 g for three typical side impact angles. Last but not least, the optimal combination of seatbelt pretensioning and the timing thereof for minimizing driver injury at each side impact angle was identified using orthogonal tests; immediate (at 0 ms) pretensioning at 80 N was applied. Our experiments show that our active seatbelt with the above parameters reduced the weighted injury criterion by 5.94%, 22.05%, and 20.37% at impact angles of 90°, 105°, and 120°, respectively, compared to that of a conventional seatbelt. The results of the experiment can be used as a reference to appropriately set the collision parameters of active seat belts for vehicles with AEB. [ABSTRACT FROM AUTHOR]

The organic-rich shale of the Qingshankou Formation (K2qn) is the most important target in the Songliao Basin. The relationship between lithofacies and source rock quality, however, is still controversial. Core observation, thin section identification, X-ray diffraction, organic geochemistry, and other analytical methods were adopted to investigate the petrology and its effects on hydrocarbon potential of the Qingshankou shale. Based on the differences in minerals, bioclastic, and fabric of laminae, four main lithofacies were defined as: (i) felsic shale (FS), (ii) clay shale (CS), (iii) bio-bearing shale (BS), and (iv) mixed shale (MS). The clay minerals content in the CS (average: 46.72 wt%) and MS (average: 41.11 wt%) was higher than that in FS (average: 39.97 wt%) and BS (average: 35.48 wt%). This classification allows the following comparative quantification of total organic carbon (TOC) content to be differentiated: CS > BS > MS > FS. Geochemical analysis indicated that the oil generation potential of the CS was the best, and the hydrocarbons generated from CS might migrate and accumulate in other lithofacies. All this knowledge could shed light on the lithofacies classification in shale systems with high clay mineral content, and may provide references for sweet spotting of the Qingshankou Formation in the Songliao Basin. [ABSTRACT FROM AUTHOR]

Ozone pollution adversely affects human health. In recent years, ozone pollution has become an important research topic and a challenge. By combining differential absorption lidar (DIAL), meteorological gradient tower data, the Weather Research and Forecasting (WRF) model, and the backward trajectories model, changes in vertical ozone concentration, the influencing factors on ozone vertical distribution, and ozone sources were analyzed in Shenzhen from September 20 to 30, 2019. Results indicated that from September 25 to 30, there was obvious residual ozone and transport at night. The analysis of ozone concentration and meteorological factors shows that the temperatures of 291.3–301.8 K and the humidity of 19.4%–71.6% were conducive to ozone formation. As height increased from less than 0.1–0.3 km, the average ozone concentration increased, and the average NO2 concentration decreased. The analysis of potential ozone sources showed that ozone was mainly transported from the northeast of China and that the highest concentration of ozone mainly comes from southeast of Jiangxi province in southeastern China. Key Points: There was obvious residual ozone and transport at night from September 25 to 30The temperatures of 291.3–301.8 K and the humidity of 19.4%–71.6% were conducive to ozone formationOzone is mainly transported from the northeast of China [ABSTRACT FROM AUTHOR]

China has made great efforts to monitor and control air pollution in the past decade. Comprehensive characterization and understanding of pollutants in three-dimensions are, however, still lacking. Here, we used data from an observation network consisting of 13 aerosol lidars and more than 1000 ground observation stations combined with a data assimilation technique to conduct a comprehensive analysis of extreme heavy aerosol pollution (HAP) over the North China Plain (NCP) from November–December 2017. During the studied period, the maximum hourly mass concentration of surface PM 2.5 reached ∼390 µ g m -3. After assimilation, the correlation between model results and the independent observation sub-dataset was ∼50 % higher than that without the assimilation, and the root mean square error was reduced by ∼40 %. From pollution development to dissipation, we divided the HAP in the NCP (especially in Beijing) into four phases: an early phase (EP), a transport phase (TP), an accumulation phase (AP), and a removal phase (RP). We then analyzed the evolutionary characteristics of PM 2.5 concentration during different phases on the surface and in 3-D space. We found that the particles were mainly transported from south to north at a height of 1–2 km (during EP and RP) and near the surface (during TP and AP). The amounts of PM 2.5 advected into Beijing with the maximum transport flux intensity (TFI) were through the pathways in the relative order of the southwest > southeast > east pathways. The dissipation of PM 2.5 in the RP stage (with negative TFI) was mainly from north to south with an average transport height of ∼1 km above the surface. Our results quantified the multi-dimensional distribution and evolution of PM 2.5 concentration over the NCP, which may help policymakers develop efficient air pollution control strategies. [ABSTRACT FROM AUTHOR]

We examine the interest rate volatility spillover between the offshore and onshore Renminbi (RMB) markets. The Hong Kong inter-bank RMB offer rate (CNY HIBOR) and the Shanghai inter-bank offer rate (SHIBOR) are used, respectively, as the interest rates for the offshore and onshore RMB markets. The results of our research show that there was significant volatility spillover between the offshore and onshore RMB prior to 21 June 2013 and that direction of the spillover from the SHIBOR to the CNY HIBOR is stronger than that from CNY HIBOR to SHIBOR. However, the spillover declined in strength between 21 June 2013 and 20 April 2016. We also find that the interest rate correlations are low and unstable. Our research reveals that the offshore RMB interest rate has been an independent system that is not determined by the onshore market, and that the determination of the offshore RMB interest rate is very complicated. The Hong Kong market is increasingly playing a more important role in the determination of the RMB. This study contributes to our understanding of the interest rate determination in China and has important implications for policy makers in terms of interest rate policies in the offshore and onshore RMB markets. [ABSTRACT FROM AUTHOR]

The mechanism between financial agglomeration and environmental pollution is an important concern for both academia and policymaking. The main objective of this paper is to study the nonlinear impacts of financial agglomeration on environmental pollution. A theoretical framework was first constructed based on the scale effect, structure effect, and technology innovation effect of financial agglomeration and a Copeland-Taylor endogenous growth model. Using the panel data of 281 Chinese prefectural-level cities from 2003 to 2019, a panel threshold regression model was introduced to estimate the nonlinear association between financial agglomeration and environmental pollution. Industrial smoke (dust) emissions and industrial wastewater discharge were adopted to quantify current environmental pollution in China. The results show that financial agglomeration had a significant effect on improving the environment characterized by gradient thresholds; also notable is that 68.64% of the cities crossed the threshold value, entering the decelerating phase of financial agglomeration inhibiting environmental pollution. Both upgrading industrial structure and enhancing marketization could reduce environmental pollution, whereas increasing human capital, environmental regulation, and energy consumption had a deteriorating effect. The three channels for financial agglomeration to reduce environmental pollution were revealed to be financial scale, financial structure, and financial technology innovation. Our findings provide strong evidence for policymaking in sustainable development. [Display omitted] • Financial agglomeration (FA) is a crucial way to improve environment pollution (EP). • We built the theoretical framework of FA and EP based on the Copeland-Taylor model. • We tested the nonlinear impacts of FA on EP using the panel threshold model. • We revealed the transmission mechanism between FA and EP. [ABSTRACT FROM AUTHOR]

Chang 7 Shale, characterized by lacustrine black organic-rich shales and interbedded siltstones, has become a target for shale oil exploration and development in the Upper Triassic Ordos Basin, China. However, the heterogeneous enrichment of organic matter (OM) has led to controversy regarding source rock evaluation and difficulty in accurate prediction of favorable zones. Sequence stratigraphy, as a tool for prediction of sedimentary deposits has encountered challenges in lacustrine deep-water environments because of rapid facies changes and limited lateral continuity of key beds. In this study, a novel method is proposed to predict OM enrichment based on parasequences division and calibration of well logging and core lithology through analyses of thin sections and geochemical data from 238 core samples, as well as available well-logging data from a selected well. Chang 7 shales were simplified into three facies in terms of sedimentary structure and mineral composition, combining geological genesis with lateral correlation. Argillaceous laminated shale (Facies 2), with the highest average total organic carbon and S 1 + S 2 values, is the most favorable facies for shale oil exploration. The Chang 7 Member was divided into 15 parasequences and six parasequence sets, within one transgressive-regressive sequence. Depositional sequences have a significant effect on the enrichment of OM, given 1) the influence of lake-level fluctuations on OM accumulation, 2) the OM enrichment determined by shale facies, and 3) the distribution of shale facies controlled by p arasequences. In particular, the most favorable locations are the bases of parasequences (generally the lower third to half from the bottom) in the TST and early RST. The application of this method to a test well showed excellent performance based on verification from the organic geochemical data of 86 samples. Five favorable targets of Facies 2 were marked within fifteen favorable locations. By linking meter-level depositional sequences with centimeter-level OM enrichment, this study provides an alternative approach to determine the target area in a single well profile and realize isochronous inter-well prediction for deep-water shales. • Shale facies and organic matter enrichment has high degree correlation. • The favorable shale facies in the TST and early RST is controlled by parasequences. • The favorable locations are the lower third to half from the bottom of parasequences. • The favorable facies was distinguished by well-logging lithology identification. • An isochronous prediction method of organic matter enrichment was proposed. [ABSTRACT FROM AUTHOR]

The role of financial agglomeration in China's green development has generated many fascinating debates for scholarly research, but few studies have considered environmental effects of financial agglomeration from the spatial spillover perspective. Taking both natural and socio-economic factors into accounts, this paper explores the interaction between financial agglomeration and green development using the panel data of 285 prefecture-level Chinese cities from 2003 to 2015. The results show that both financial agglomeration and green development have demonstrated a trend of spatial convergence. Secondly, financial agglomeration can promote the green development of both focal and surrounding cities. Thirdly, financial agglomeration is conducive to enhance regional green development level in Western China, while only Eastern and Central China witness significant spatial spillover effects. Fourthly, the direct effect of financial agglomeration on green development at the city level exists, whereas megacities and large cities witness a significantly adverse spatial spillover effect. This paper also presents policy recommendations. [ABSTRACT FROM AUTHOR]

Fine particle with diameter <2.5 μm (PM 2.5 ) have important direct and indirect effects on human life and activities. However, the studies of fine particle were limited by the lack of monitoring data obtained with multiple fixed site sampling strategies. Mobile monitoring has provided a means for broad measurement of fine particles. In this research, the potential use of mobile lidar to map the distribution and transport of fine particles was discussed. The spatial and temporal distributions of particle extinction, PM 2.5 mass concentration and regional transport flux of fine particle in the planetary boundary layer were investigated with the use of vehicle-based mobile lidar and wind field data from north China. Case studies under different pollution levels in Beijing were presented to evaluate the contribution of regional transport. A vehicle-based mobile lidar system was used to obtain the spatial and temporal distributions of particle extinction in the measurement route. Fixed point lidar and a particulate matter sampler were operated next to each other at the University of Chinese Academy of Science (UCAS) in Beijing to determine the relationship between the particle extinction coefficient and PM 2.5 mass concentration. The correlation coefficient (R 2 ) between the particle extinction coefficient and PM 2.5 mass concentration was found to be over 0.8 when relative humidity (RH) was less than 90%. A mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, was used to obtain profiles of the horizontal wind speed, wind direction and relative humidity. A vehicle-based mobile lidar technique was applied to estimate transport flux based on the PM 2.5 profile and vertical profile of wind data. This method was applicable when hygroscopic growth can be neglected (relatively humidity<90%). Southwest was found to be the main pathway of Beijing during the experiments. [ABSTRACT FROM AUTHOR]

Accurate and comprehensive knowledge of the atmospheric environment and its evolution within the coastal ocean boundary layer are necessary for understanding the sources, chemical mechanisms, and transport processes of air pollution in land, sea, and atmosphere. We present an overview of coastal ocean boundary layer detection technology and equipment in China and summarize the progress and main achievements in recent years. China has developed a series of coastal ocean boundary layer detection technologies, including Light Detection and Ranging (LIDAR), turbulent exchange analyzer, air-sea flux analyzer, stereoscopic remote sensing of air pollutants, and oceanic aerosol detection equipment to address the technical bottleneck caused by harsh environmental conditions in coastal ocean regions. Advances in these technologies and equipment have provided scientific assistance for addressing air pollution issues and understanding land-sea-atmosphere interactions over coastal ocean regions in China. In the future, routine atmospheric observations should cover the coastal ocean boundary layer of China. [Display omitted] [ABSTRACT FROM AUTHOR]

The air pollution in China has presented remarkable regional and complex characteristics, and particle explosive growth events happened frequently. In view of the domestic situation, a new synergistic approach, which could detect particle pollution over large area rapidly, is urgently needed. A rapid detection approach based on multiple mobile vehicle-based lidar systems is proposed to meet the needs of regional particle pollution observation in this paper. Take the Jing-Jin-Ji (the abbreviation of Beijing-Tianjin-Hebei) area for example, the methodology and practice of the rapid synergistic approaches with three sets of mobile vehicle-based lidars are presented. On the premise of synergistic observation scheme design and data quality control, we conducted a synergistic observation of aerosol in Jing-Jin-Ji area on 4 November 2017. Then the spatial distribution and transport characteristics of particle pollution in this area are discussed. The synergistic observation results show that high aerosol extinction was observed on the southwest pathway in this case. Furthermore, the spatial distribution characteristics of aerosol optical depth and boundary layer height were analyzed in this study. The comprehensive analysis of synergistic observation results, backward trajectories, and near-surface concentration of PM 2.5 based on in situ instrument further illustrated the transport from the southwest pathway strongly affects air quality. The synergistic approach based on multiple mobile vehicle-based lidars provides an effective approach on regional pollution tracking and characterizing within hours. • A synergistic approach for regional pollution tracking based on multiple mobile vehicle-based lidars was presented. • Characteristics of the regional distribution of aerosol particles in Jing-Jin-Ji were observed. • The significant AOD and BLH was found together on the southwest pathway in the early stage of haze development. [ABSTRACT FROM AUTHOR]

Long-term ozone lidar routine measurements are sparse in China. In this study, we used one year of continuous ozone lidar measurements to systematically investigate the effects of synoptic patterns on the vertical structure of ozone during high ozone episodes in Hong Kong. The height of the near-surface ozone layer was identified and compared with that of the mixing layer. The results showed that Hong Kong was greatly affected by ozone transport from the Pearl River Delta region when a tropical cyclone ("C" pattern) or a trough ("T" pattern) existed. When a high-pressure center was located to the north ("H" pattern) or when both a high-pressure system and a tropical cyclone existed ("CH" pattern), Hong Kong was affected by ozone transport from southeastern or southern China. Substantial amounts of ozone were transported within a layer near the ground with an average height of 0.83, 0.75, 0.94, and 0.85 km under the C, H, CH, and T synoptic patterns, respectively. Variation in the near-surface ozone layer height was consistent with that of the mixing layer height. Weak vertical mixing resulted in a shallow near-surface ozone layer under the C and H synoptic patterns. Due to the combined effect of near-surface transport and suppressed vertical mixing, the ozone concentrations were extremely high near the ground but rapidly declined with height under the C synoptic pattern. Our investigations of the vertical structure of ozone contribute to filling the knowledge gap between synoptic patterns and the evolution of high surface ozone episodes. • One-year lidar measurements of ozone vertical structure were investigated. • Ozone transport and vertical mixing were characterized under four synoptic patterns. • Substantial amounts of ozone were transported in a near-surface layer below 1 km. • The near-surface ozone layer height was largely determined by vertical mixing. • Ozone concentrations rapidly declined with height under the cyclone-related pattern. [ABSTRACT FROM AUTHOR]

The effects of petroleum retention within and expulsion from five intervals within the Triassic Chang 7 Member in the Ordos Basin in China have been demonstrated by deciphering a large suite of petrologic, organic petrographic, and organic geochemical analyses on 106 core samples. Organic properties and lithological heterogeneities control the amount and chemical composition of retained petroleum. Enrichment of aliphatic hydrocarbons in the silty, organic-lean intervals versus enrichment of aromatic fluids in the clayey, organic-rich units are probably caused by compositional fractionation occurred during primary and short-distance secondary migration. Migration of excess petroleum from organic-rich units to those organic-lean counterparts was further corroborated by the negative expulsion efficiencies calculated using a mass-balance model in the organic-lean intervals. Capillary pressure difference induced by the contrast in pore throat size of the clayey, organic-rich versus the silty, organic-lean intervals is postulated to be the major driver for the migration. A significant implication of this study is that the hydrocarbons in the first and fourth intervals constitute potential petroleum exploitation targets, given (i) improved oil quality caused by enriched aliphatic compounds versus viscous aromatic and polar compounds, (ii) lower organic matter sorption affinities, (iii) relatively high contents of brittle minerals in these two intervals. Despite its high content of retained hydrocarbons, the organic-rich fifth interval is not the best target, which is mainly due to the high sorption affinity of the organic matter structure, thereby causing low oil mobility and producibility. • The organic richness and lithological compositions control the amount and chemical composition of retained petroleum. • Primary migration leads to the fractionation of hydrocarbon compositions in organic-lean and organic-rich intervals. • Intervals with high oil saturation and negative expulsion efficiencies are potential petroleum exploitation targets. [ABSTRACT FROM AUTHOR]

As the development of megacities, combined air pollution has been of increasing concern in China, which is composed by primary pollution, such as Nitrogen dioxide (NO 2), and the followed secondary pollution under certain meteorology circumstances and high concentration of precursors, such as tropospheric ozone, formaldehyde (HCHO) and fine particles. During PRIDE-GBA 2018 Campaign (Particles, Radicals, Intermediates from oxiDation of primary Emissions in Great Bay Area), we performed the high resolution vertical observations of pollution gases and aerosol, which are significant but scarce indexes in studying the mechanisms of tropospheric pollution, using remote sensing techniques. NO 2 and HCHO column densities and vertical profiles are reconstructed from data of multi-axis differential optical absorption spectroscopy (MAX-DOAS). Tropospheric ozone profile and aerosol extinction are retrieved by the differential absorption light detection and ranging (LIDAR) system. In order to verifying the accuracy, we evaluated the consistency and reliability of MAX-DOAS and LIDAR measurements. The results showed reasonable agreement with in-situ and off-line observations at Canton Tower. A typical combined pollution process from Sep 29 to Oct 10 was analyzed in detail. More than 200 μg/m3 tropospheric ozone in this case was considered from the anthropogenic sources, including industry, power plant, residential and transportation. The high emission from local industry and polluted air transport from northeast brought the main precursors of this pollution process. The photochemical formation of tropospheric ozone was turned into a VOC-limited regime on polluted days. • Vertical distribution of NO 2 , HCHO and aerosol were derived by MAX-DOAS. • High resolution tropospheric ozone profiles were observed by LIDAR. • Validations were performed using in-situ and off-line data at Canton Tower. • As high as 300 μg/m3 ozone was observed at Guangzhou during the campaign. [ABSTRACT FROM AUTHOR]

Ground ozone (O 3 ) pollution has emerged as a prominent environmental concern in eastern cities of China, particularly during the summer and autumn seasons. However, a comprehensive investigation into the three-dimensional (3-D) evolution characteristics of O 3 within complicated urban environments, especially in lake-land environment, is notably scarce. To enhance our understanding of the mechanisms underlying elevated O 3 concentrations within a 3-D scale, this study employed an ozone lidar to delineate vertical ozone profiles in Changzhou, a typical city in China with complicated anthropogenic and biogenic emissions and complex land cover. The process analysis tool integrated into the Weather Research and Forecasting with Chemistry (WRF-Chem) model was further utilized to analyze the formation processes of O 3 . The results unveil a persistent O 3 pollution episode lasting over 15 days in Changzhou during the study period, with multiple peaks exceeding 200 μg m⁻³. Notably, O 3 predominantly accumulated within the boundary layer, confined below 1.2 km. Both ground and vertical contributions to this pollution were mainly due to local chemical reactions, with a maximum near-surface contribution reaching 19 ppb h -1 and a vertical contribution of 10 ppb h -1 at the height of 900 ± 200 m. Furthermore, episodes of the enhanced O 3 concentrations on August 9 and August 26, 2021, were influenced by external advection process. Our study also found that local circulation plays an important role in the accumulation of surface O 3 during certain periods. There was a temperature difference between the surface of Lake Tai and the adjacent land, resulting in the formation of lake-land breezes that facilitate the transport of O 3 from the lake surface to the terrestrial environment during pollution events. Our study emphasizes the necessity of reducing local pollutant emissions and implementing joint emission controls as the primary strategies for mitigating O 3 pollution in Changzhou and the surrounding region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The research on the mechanism of combined air pollution in the Yangtze-Huaihe region, which is characterized by unique meteorological and geographical conditions and pollution emission characteristics, is still insufficient. We performed an experiment on key pollutants and an ozone formation study in Hefei, which is a pivotal city in the Yangtze-Huaihe region, from September 1 to 20, 2020. The aerosols retrieved via two-dimensional Multi-axis Differential Optical Absorption Spectroscopy (2D-MAX-DOAS) with a Boltzmann-shaped a priori profile had the best agreement with the results of Light Detection and Ranging (LIDAR) and sun-photometer measurements among the three typical a priori profiles (Gaussian, Boltzmann, and exponential shapes). The correlation coefficients of the near-surface gas concentrations retrieved using both 2D-MAX-DOAS and in situ measurements were 0.86 (NO 2 ) and 0.61 (HCHO). The high NO 2 and HCHO concentrations were observed at azimuths of 180° and 315° at heights of 0.8-1.5 km, and they may have been emitted by aircrafts. Importantly, the ratio of HCHO to NO 2 during a typical pollution episode revealed that the factors controlling the O 3 formation changed with altitude: VOCs (surface) to NOx (0.4 km) to transition (1.0 km) to VOCs (1.6 km). Moreover, the effect of VOCs on the O 3 generation was stronger than that of NOx, especially in the downtown area of Hefei. When the ratio of HCHO to NO 2 was 3.55-7.46, the ozone concentration in Hefei could be controlled well, especially at the optimal value of 5.50., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Accurately quantifying the concentration and transport flux of atmospheric fine particulate matter (PM 2.5 ) is vital when attempting to thoroughly identify the pollution formation mechanism. In this study, the mobile lidar measurements in Beijing on heavily polluted days in December from 2015 to 2018 are presented. The lidar was mounted on a vehicle, which could perform measurements along designated routes. On the basis of mobile lidar measurements along closed circuits of the 6th Ring Road around Beijing, the spatial distribution and transport flux of PM 2.5 in Beijing were determined with information of wind field. In the spatial distribution, both the concentration and transport of PM 2.5 were revealed to be more significant in the southern section of Beijing. The regional transport layer at heights < 1.3 km plays an important role in pollution formation. The maximum transport flux reached 1600 μg/(m 2 *sec) on 11 December 2016. With the aerosol boundary layer height determined from the image edge detection (IED) method, the inter-annual variations of the aerosol boundary layer height (ABLH) were also analysed. The ABLH decreased from 0.73 to 0.46 km during the same heavy pollution period from 2015 to 2018. Increasingly adverse aerosol boundary layer (ABL) meteorological factors, including lower ABLH, light winds, temperature inversions, and accumulated moisture, have become necessary for pollution formation in Beijing., (Copyright © 2021. Published by Elsevier B.V.)

Beijing-Tianjin-Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental governance. Mixing layer height (MLH) is a key factor influencing the diffusion of air pollutants. It plays an important role on the evolution of heavy pollution events. Light detection and ranging (lidar), is an effective remote-sensing tool, which can retrieve high spatial and temporal evolution process within mixing layer (ML), especially the variation of MLH. There are many methods to retrieve MLH, but each method has its own applicable limitations. The Mie-lidar data in Beijing was firstly used to compare three different algorithms which are widely used under different pollution levels. We find that the multi-layer structure near surface may cause errors in the detection of mixing layer. The MLH retrieved based on image edge detection was better than another two methods especially under heavy polluted episode. Then we applied this method to investigate the evolution of the mixing layer height during a pollution episode in December 2016. MLH at Gucheng county showed the positive correlation with the concentration of particulate matters during the start of this pollution episode. The elevated pollution level in Gucheng was not associated with MLH's decrease, and the significantly increased particulate matters raised the boundary layer, which trapped the pollutants near the surface., (Copyright © 2018. Published by Elsevier B.V.)

This paper studied the predation and dispersal of Lithocarps glaber seeds by rodents in the Tiantong National Forest Park (29 degrees 48'N, 121 degrees 47'E) of Ningbo City, Zhejiang Province. Five seeds release transects (three in evergreen broad-leaved forest, one in Pinus messoniana forest, and one in shrub), and two seeds release states (covered/uncovered and tagged/untagged) were set up. Iron snare traps were baited to determine the effects of rodents on seeds disappearance. The results showed that two species of rodents, Niviventer confucianus and N. fulvescensi, were the potential predators and dispersers of the seeds. The lost seeds labeled with small piece of tintags could be classified into three categories, i. e., 1) seeds consumed by rodents, with tags stuck seed fragments; 2) seeds cut off from tags, with tags kept only; and 3) both seeds and tags disappeared. The loss rate of seeds was high at the beginning of the observation, and then decreased gradually. The daily seeds disappearance rate (DS-DR) was variable in different habitats, with the highest (1.03%) in evergreen broad-leaved forest and the lowest (0.32%) in shrub. The proportion of these three categories was different, and related with habitat types. The difference of DSDR between covered and uncovered states was statistically significant (P < 0.05), with a higher DSDR under uncovered state. No significant difference was observed between the DSDR of tagged and untagged. The distance of seeds dispersal by rodents was within 6.7 m.

Five mature plants of Castanopsis fargesii population were randomly chosen to study the spatial and temporal pattern of its seed rain in Tiantong National Forest Park, Zhejiang Province in 2003. The duration of seed rain observed from the five samples was about 45 days, from November 3rd to December 16th, with a distinguishable dropping peak between November 18th and 27th. The average seed rain density estimated from the traps deployed under the crown was 112.8 seeds.m(-2), ranging from 70 to 239.5 seeds.m(-2). Of the total acorns collected by seed traps, the viable accounted for 27.3%, the immature 25.7%, the eaten by rodents 5.0%, and the infected by larvae 42.0%. The acorns on the ground mainly distributed under the parent tree crown within 8 m from the trunk, and the spatial pattern of seed density on the ground fitted the quadratic distribution.