Coastal Area Of South China Research Articles

Spatiotemporal distribution and mechanism of Mesozoic magmatism in the Taiwan Strait and its adjacent areas: insights from seismic, geochemical, and geochronological data

ABSTRACT This paper presents a complete map of the Mesozoic volcanic-plutonic complexes in the Taiwan Strait and its adjacent areas in terms of seismic profiles, ages, geochemistry, isotopic systematics, and published data. Two periods of igneous activity in the Taiwan Strait can be distinguished by seismic profiles: Jurassic (200.4–148.2 Ma); and Latest Jurassic/Cretaceous to Maastrichtian (144–66 Ma), of which the Cretaceous is the best preserved and could possibly be the most widespread. Mesozoic magmatic activity with the NE-striking distribution was migrating southeastward (oceanward). LA-MC-ICPMS zircon U – Pb dating yields the age data of 109.5 ± 0.4 Ma for PTDH1 granodiorite and 92.6 ± 0.4 Ma for PTDH4 rhyolite in the Taiwan Strait, respectively. The 581.66-m-thick Upper Jurassic volcanic rocks of the Chuan2 well are the thickest Mesozoic igneous rocks in the Taiwan Strait. The petrogenetic discrimination diagram of the Cretaceous volcanic-plutonic complexes along the coast of South China and the Taiwan Strait generally is belonging to volcanic arc or intraplate type calc-alkaline rock series. The high potassium calc-alkaline rock series of the Cretaceous volcanic-plutonic complexes that is most widely distributed in the coastal areas of South China and the Taiwan Strait. They are controlled by the subduction of the Palaeo-Pacific domain.

In situ observations of rain rate and precipitation microphysics over the coastal area of South China: Perspectives for satellite validation

Abstract This study investigates precipitation observed by a set of collocated ground-based instruments in Zhuhai, a coastal city located at the southern tip of the Pearl River Delta of Guangdong Province in South China. Seven months of ground-based observations from a tipping-bucket rain gauge (RG), two laser disdrometers (PARSIVEL and PWS), and a vertically-pointing Doppler Micro Rain Radar-2 (MRR), spanning from December 2021 to July 2022, are statistically evaluated to provide a reliable reference for China’s spaceborne precipitation measurement mission. Rainfall measurement discrepancies are found between the instruments, though the collocated deployment mitigates uncertainties originating from spatial/temporal variabilities of precipitation. The RG underestimates hourly rain amounts at the observation site, opposite to previous studies, leading to 18.2% percent bias (Pbias) of hourly rain amounts when compared to the PARSIVEL. With the same measurement principle, the hourly-accumulated rain between the two laser disdrometers has a Pbias of 15.3%. Discrepancies between MRR and disdrometers are assumed to be due to different temporal/spatial resolution, instrument sensitivities and observation geometry, with a Pbias of mass-weighted mean diameter and normalized intercept parameter of gamma size distribution less than 9%. The vertical profiles of drop size distribution (DSD) derived from the MRR are further examined during extreme rainfalls in the East Asia monsoon season (May, June, and July). Attributed to the abundant moisture which favors the growth of raindrops, coalescence is identified as the predominant effective process and the raindrop mass-weighted mean diameter increases by 33.7% when falling from 2000 m to 600 m during the extreme precipitation event in May.

Distribution and Risk Assessment of Organophosphate Esters in Agricultural Soils and Plants in the Coastal Areas of South China.

Organophosphate esters (OPEs) are frequently used as flame retardants and plasticizers in various commercial products. While initially considered as substitutes for brominated flame retardants, they have faced restrictions in some countries due to their toxic effects on organisms. We collected 37 soil and crop samples in 20 cities along the coast of South China, and OPEs were detected in all of them. Meanwhile, we studied the contamination and potential human health risks of OPEs. In soil samples, the combined concentrations of eight OPEs varied between 74.7 and 410 ng/g, averaging at 255 ng/g. Meanwhile, in plant samples, the collective concentrations of eight OPEs ranged from 202 to 751 ng/g, with an average concentration of 381 ng/g. TDCIPP, TCPP, TCEP, and ToCP were the main OPE compounds in both plant and soil samples. Within the study area, the contaminants showed different spatial distributions. Notably, higher OPEs were found in coastal agricultural soils in Guangdong Province and crops in the Guangxi Zhuang Autonomous Region. The results of an ecological risk assessment show that the farmland soil along the southern coast of China is at high or medium ecological risk. The average non-carcinogenic risk and the carcinogenic risk of OPEs in soil through ingestion and dermal exposure routes are within acceptable levels. Meanwhile, this study found that the dietary intake of OPEs through food is relatively low, but twice as high as other studies, requiring serious attention. The research findings suggest that the human risk assessment indicates potential adverse effects on human health due to OPEs in the soil-plant system along the coast of South China. This study provides a crucial foundation for managing safety risks in agricultural operations involving OPEs.

Metagenomic and metabolomic profiling of dried shrimp (Litopenaeus vannamei) prepared by a procedure traditional to the south China coastal area.

Sun-drying is a traditional process for preparing dried shrimp in coastal area of South China, but its impacts on nutrition and the formation of flavor-contributory substances in dried shrimp remain largely unknown. This study aimed to examine the effects of the production process on the microbiota and metabolites in dried shrimp. 16S rDNA amplicon sequencing was employed to identify 170 operational taxonomic units (OTUs), with Vibrio, Photobacterium, and Shewanella emerging as the primary pathogenic bacteria in shrimp samples. Lactococcus lactis was identified as the principal potential beneficial microorganism to accrue during the dried shrimp production process and found to contribute significantly to the development of desirable shrimp flavors. LC-MS-based analyses of dried shrimp sample metabolomes revealed a notable increase in compounds associated with unsaturated fatty acid biosynthesis, arachidonic acid metabolism, amino acid biosynthesis, and flavonoid and flavanol biosynthesis throughout the drying process. Subsequent exploration of the relationship between metabolites and bacterial communities highlighted the predominant coexistence of Bifidobacterium, Clostridium, and Photobacterium contributing heterocyclic compounds and metabolites of organic acids and their derivatives. Conversely, Arthrobacter and Staphylococcus were found to inhibit each other, primarily in the presence of heterocyclic compounds. This comprehensive investigation provides valuable insights into the dynamic changes in the microbiota and metabolites of dried shrimps spanning different drying periods, which we expect to contribute to enhancing production techniques and safety measures for dried shrimp processing.

Key traits influencing the resistance of Eucalyptus camaldulensis to wind damage in coastal areas of South China.

China is one of the countries in the world most seriously affected by typhoons, which pose a great threat to the eucalyptus plantation industry. However, few studies have comprehensively accounted for the impact of key traits on the wind damage/resistance of eucalyptus. To identify the key factors affecting the wind resistance of eucalyptus, 20 eucalyptus genotypes were selected; a total of 18 traits, including the wind damage index, growth traits, and wood traits, were measured, and the wind resistance was determined via the tree-pulling test. Correlation, principal component, canonical correlation, and path analyses were performed to evaluate these traits. Correlation analysis revealed that the wind resistance of eucalyptus plants was related to the tree height, volume, and duration of stress wave propagation. Principal components and tree-pulling variables were further used for correlation and path analyses. Canonical correlation analysis and the PA-OV model showed that holocellulose and lignin contents and fiber width, as well as growth traits, were important factors affecting the stability of standing trees under typhoon conditions. The key traits influencing the wind resistance of Eucalyptus camaldulensis, which may provide a reference for evaluating the wind resistance of Eucalyptus varieties for forest management, were identified. This study provides a knowledge base for forest management and planning in typhoon-prone coastal areas, and provides a theoretical basis for the breeding and genetically improving eucalyptus stocks based on wind resistance characteristics.

The important boundary role of Lianhuashan fault zone in late Mesozoic magmatism of South China: New insights from ambient noise tomography and teleseismic data

The Lianhuashan fault zone (LHSFZ), which divides the Cathaysia Block (CB) into the coastal volcanic and Cathaysian fold belts, is an important intraplate lineament in the CB. Its fine structure is crucial to understand the Late Mesozoic tectonic evolution of South China. Herein, the fine S-velocity structure of the LHSFZ above 6.0 km and its depth extent were studied by ambient noise tomography and teleseismic relative travel-time residual analysis using a dense (∼1 km station spacing) seismic array spanning 123 km at the southern end of the LHSFZ. Our results indicate that the area within 70 km of the coast has a higher S-wave velocity, which extends to the southeast below 6 km. We propose that the high velocity anomaly is a result of magma intrusion caused by the subduction of the Paleo-Pacific plate in the Late Mesozoic, and the magma upwelling trajectory occurs from the coast to the inland. In addition, a low-velocity anomaly is found beneath the core area of the LHSFZ at a depth of 3–6 km, which is more evident in the S-wave than in the P-wave and corresponds well with the presence of hot springs and earthquakes. We hypothesize that the low-velocity anomaly represents the existing fault system of the Late Mesozoic volcanoes, which now provides channels for fluid migration and facilitates seismicity. Our model suggests that the LHSFZ plays a key role in the evolution of the coastal areas of South China.

A Coupled Tensor–DEM–FEM Model for the Whole Process of Internal Fine-Scale Damage to Surface Damage in Red-Bed Soft Rocks in the Coastal Area of South China

Calculation and characterization of the whole process of internal microscopic damage to surface damage in red-bed soft rock is a theoretical research difficulty and an urgent need for engineering safety protection. However, the current study cannot accurately and directly correlate internal and external damage. Therefore, in this paper, a coupled tensor–DEM–FEM model is proposed to deal with surface damage by indoor triaxial test digital image processing (DIC), internal damage by FJM acoustic emission study, and internal and external damage by moment tensor correlation. The study demonstrates that the whole process damage process of the red-bed soft rock peak front can be divided into six distinct phases, with early damage beginning with the elastic phase; the local strain divergence value begins to spiral out of control during the period of crack acceleration development; the overall acoustic emission intensity distribution is in the range of [−8.5, −6.3] in two dimensions and in the range of [−11, −9] in three dimensions; the R were between −40 and 40, which corresponded to the results of the indoor tests. A model has been developed that allows a direct reflection of the whole damage process. The method can be used to better understand the disaster mechanism and guide engineering practice.

Large-scale moisture transport and local-scale convection patterns associated with warm-sector heavy rainfall over South China

Warm-sector heavy rainfall (WSHR) frequently occurs in South China, causing severe floods and posing serious threats to human health and societal systems there. However, its moisture sources, transport pathways, and triggering mechanisms still warrant in-depth investigations. Here we identify three different clusters of moisture sources and transport pathways of WSHR in South China during 1982–2015 and reveal their associated atmospheric circulations and local-scale convection patterns. In the case of cluster 1, a strong anomalous high-pressure system and an anomalous low-pressure system jointly induce strong southwesterly air-flows, and a local convergent flow and ascending motions appear over the west of South China, thereby providing sufficient water vapor from the Indian Ocean and favorable dynamical conditions for triggering WSHR events in the west of South China. In contrast, the trajectories of cluster 2 are characterized by strong easterly air-flows that supply a large amount of water vapor from the Northwest Pacific and induce a strong convection, favoring the WSHR occurrences in the eastern coastal area of South China. In the case of cluster 3, a high-pressure anomaly and a shallow low-pressure system respectively cover the southeast and northwest portions of South China. This circulation pattern causes a strong anomalous southerly wind and induces an anomalous convergent flow over entire South China, thereby transporting sufficient water vapor from the South China Sea and triggering WSHR events over South China. Differing from WSHR, the moisture of frontal heavy rainfall events over South China is not only contributed by the three dominant ocean-originating moisture transport paths but also by the continent-originating paths. The findings reported here highlight that the atmospheric trajectories and synoptic systems jointly modulate the spatial variation of heavy rainfall events in South China by dominating large-scale transport pathways of water vapor and local-scale convection patterns.

OSL chronological evidence reveals one of the earliest island-type Neolithic sites in the coastal area of South China

Many prehistoric sites are preserved in the southeast China coastal area; however, it is still unclear when ancient human activity occurred owing to a lack of chronological evidence, which is unfavourable for research on the coupling of prehistoric man-earth relationships. In this study, we present an optically stimulated luminescence (OSL) chronology analysis of two profiles (T1 and T4) collected from the Neolithic Jianhu (JH) site on Haitan Island, South China. The single-aliquot regenerative-dose (SAR) protocol for coarse silt (38–63 μm) quartz was used to determine the equivalent dose (De). The results showed that the OSL technology is reliable and of great value for archaeochronology in coastal aeolian regions. The results suggest that the JH site is one of the earliest Neolithic sites in the coastal area of Fujian. The ages of cultural layers with ancient human activities at the JH site varied from 7.4 ± 1.13 to 5.77 ± 0.35 ka, thereby making the JH site the earliest Neolithic site in the coastal area of Fujian. The sand-tempered pottery unearthed from the JH site can be used as direct evidence of ancient human survival, and its age is 6.33 ± 0.21 ka with a high precision, which presents the earliest OSL data on pottery in South China. We also discuss the regional environmental background of ancient human activity. The Keqiutou culture corresponds to a period of relatively high sea level and a superior natural environment on Haitan Island. The sea retreat 5.7 ka ago was a crucial factor driving prehistoric human migration to the Fuzhou Basin and Taiwan Island.

Genome-Wide Characterization of PIN Auxin Efflux Carrier Gene Family in Mikania micrantha.

Mikania micrantha, recognized as one of the world’s top 10 pernicious weeds, is a rapidly spreading tropical vine that has invaded the coastal areas of South China, causing serious economic losses and environmental damage. Rapid stem growth is an important feature of M. micrantha which may be related to its greater number of genes involved in auxin signaling and transport pathways and its ability to synthesize more auxin under adverse conditions to promote or maintain stem growth. Plant growth and development is closely connected to the regulation of endogenous hormones, especially the polar transport and asymmetric distribution of auxin. The PIN-FORMED (PIN) auxin efflux carrier gene family plays a key role in the polar transport of auxin and then regulates the growth of different plant tissues, which could indicate that the rapid growth of M. micrantha is closely related to this PIN-dependent auxin regulation. In this study, 11 PIN genes were identified and the phylogenetic relationship and structural compositions of the gene family in M. micrantha were analyzed by employing multiple bioinformatic methods. The phylogenetic analysis indicated that the PIN proteins could be divided into five distinct clades. The structural analysis revealed that three putative types of PIN (canonical, noncanonical and semi-canonical) exist among the proteins according to the length and the composition of the hydrophilic domain. The majority of the PINs were involved in the process of axillary bud differentiation and stem response under abiotic stress, indicating that M. micrantha may regulate its growth, development and stress response by regulating PIN expression in the axillary bud and stem, which may help explain its strong growth ability and environmental adaptability. Our study emphasized the structural features and stress response patterns of the PIN gene family and provided useful insights for further study into the molecular mechanism of auxin-regulated growth and control in M. micrantha.

Characteristics and Health Risks of Phthalate Ester Contamination in Soil and Plants in Coastal Areas of South China.

Phthalate esters (PAEs) are widely used as plasticizers in industrial and commercial products, and are classified as endocrine-disrupting compounds. In this study, we investigated the contamination characteristics and health risks of PAEs in the soil–plant system in coastal areas of South China. PAEs were detected in soil and plant samples at all 37 sampling sites. The total concentration of the 15 PAEs in soil samples ranged from 0.445 to 4.437 mg/kg, and the mean concentration was 1.582 ± 0.937 mg/kg. The total concentration of the 15 PAEs in plant samples ranged from 2.176 to 30.276 mg/kg, and the mean concentration was 8.712 ± 5.840 mg/kg. Di(2-Ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the major PAEs compounds in all samples. The selected contaminants exhibited completely different spatial distributions within the study area. Notably, higher concentrations of PAEs were found in the coastal Guangdong Province of South China. The average noncarcinogenic risks of Σ6 PAEs were at acceptable levels via dietary and nondietary routes. However, the noncarcinogenic risks posed by DEHP and DBP at some sampling sites were relatively high. Furthermore, dietary and nondietary carcinogenic risks were very low for BBP, but carcinogenic risks posed by DEHP via diet. The results suggest that PAEs in the coastal soil–plant system in South China, through human risk assessment, will induce some adverse effects on human health, especially in children. This study provides an important basis for risk management of PAEs in agriculture, and safety in coastal areas of South China.

New research on the origin of the late Quaternary Old Red Sand in the coastal area of South China

A late Quaternary red sandy sediment called the Old Red Sand is widely distributed in coastal South China. Most studies have considered it a single sand body composed of wind-transported beach sand. However, the Old Red Sand also contains silt and clay. To determine the implications of this fine fraction for the origin of the Old Red Sand, four sections were studied using various depositional analyses. Under a scanning electron microscope, quartz particles in the fine fraction are well rounded, with abundant aeolian marks on their surfaces. The grain size is homogeneous and comparable to that of typical loess. The diffuse reflectance spectroscopy results suggest a higher content of haematite than goethite within the fine fraction, indicating subaerial deposition without strong hydration. The geochemical composition of the fine fraction is close to that of the upper continental crust and comparable to that of typical aeolian deposits, indicating the extensiveness of material sources, with terrestrial dust being fully mixed by wind over a large area. The depositional characteristics, sedimentary environment and provenance of the fine fraction are markedly different from those of the coarse fraction, which is composed of near-source beach sand. Therefore, the Old Red Sand is not a deposit with a single source. Both near-source coarse beach sand and exotic fine dust contributed to the formation of the deposit in the late Pleistocene, especially the last glacial period. The fine fraction is a key factor contributing to the cementation and redness of the sand body.

Multiscale Perspectives on an Extreme Warm-Sector Rainfall Event over Coastal South China

On 22 June 2017, an extreme warm-sector rainfall event hit the western coastal area of South China, with maximum hourly and 12-h rainfall accumulations of 189.4 and 464.8 mm, respectively, which broke local historical records. Multisource observations were used to reveal multiscale processes contributing to the extreme rainfall. The results showed that a marine boundary layer jet (BLJ) coupled with a synoptic low-level jet (LLJ) inland played an important role in the formation of an extremely humid environment with a very low lifting condensation level of near-surface air. Under the favorable pre-convective conditions, convection was initialized at a mesoscale convergence line, aided by topographic lifting in the evening. During the nocturnal hours, the rainstorm developed and was maintained by a quasi-stationary mesoscale outflow boundary, which continuously lifted warm, moist air transported by the enhanced BLJ. When producing the extreme rainfall rates, the storm possessed relatively weak convection, with the 40 dBZ echo top hardly reaching 6 km. The extreme rainfall was produced mainly by the warm rain microphysical processes, mainly because the humid environment and the deep warm cloud layer facilitated the clouds’ condensational growth and collision–coalescence, and also reduced rain evaporation. As the storm evolved, the raindrop concentration increased rapidly from its initial stage and remained high until its weakening stage, but the mean raindrop size changed little. The extreme rain was characterized by the highest concentration of raindrops during the storm’s lifetime with a mean size of raindrops slightly larger than the maritime regime.

Stochastic Medium Model for the Settlement Calculation of Prefabricated Vertical Drains of Soft Soil Foundations in the Coastal Area of South China

The prefabricated vertical drain (PVD) is an essential means to mitigate the settlement of soft soil foundations in coastal areas of South China. The commonly used elastoplastic analytical method cannot directly reflect the interaction of different PVDs and the resulting displacement of soft soil. At the same time, these elastoplastic analysis and numerical simulation methods are greatly influenced by the values adopted for rock and soil material parameters. In this paper, we present a stochastic medium model that can directly reflect the interaction of different PVDs and the resulting displacement of soft soil. It is not affected by the characteristics of rock and soil themselves and can also reflect the actual deformation process of soft soil. According to engineering practice, the settlement curves of soft soil foundations in coastal areas of South China with PVDs exhibited distinct normal distribution characteristics, which was consistent with the description of settlement by the stochastic medium model. Hence, based on the stochastic medium model, this paper analyzed the settlement mechanism of PVDs and established a stochastic medium model for the settlement calculation of PVDs. A function for the soft soil foundation in the coastal area of South China cross-section settlement curve was presented by back analysis of the PVD model. We chose the stochastic medium model based on this methodology to explore the interaction between different PVDs. The above models were then applied to an expressway in South China. Comparing actual settlement monitoring values to calculated values obtained with the PVD model, the error between the two models was less than 15%. This research provides a new settlement calculation method of PVDs in soft soil foundations in the coastal area of South China and a new basis for designing soft soil foundations.

Shallow Crustal Structure of S-Wave Velocities in the Coastal Area of South China Constrained by Receiver Function Amplitudes

As a traditional method, passive seismic exploration is used to construct the body-wave velocity structure of the upper crust, but it is cost-ineffective and depth-limited when applied to large areas. In this study, we use another more economical method to determine the S-wave velocity (SWV) of the upper crust based on the principle that the amplitude of the direct P-wave on the teleseismic receiver function is sensitive to the upper crust. Using the amplitudes of the massive receiver functions from permanent broadband seismic stations, the SWV structure of the upper crust is obtained in the coastal area of South China (CASC). A pattern of high to low SWVs is exhibited across the study area, with SWVs varying about 2.5–3.7 km/s from west to east. In the profile parallel to the coastline, lateral variations in the SWV correspond to the fault zone, indicating that the cutting depth of most coastal faults is approximately 10 km. Referring to previous studies, we deduce that the low SWV in most sub-areas can be interpreted as the joint effect of the sedimentary layer of the alluvial plain and the accumulation of underground heat flows, in addition to multistage fracturing tectonism. Moreover, the gradual change in the SWV in each profile from the surface to approximately 10 km is correlated with multiple invasions and the coverage of volcanic rocks, to a certain extent.

New chronological evidence reveals a continuously inhabited Neolithic–historical settlement in south China

The Xindian Ancient City (XAC) site is the most complete and frequently excavated urban site in the lower reaches of the Minjiang River. Archaeological and chronological research of this area helps clarify the history of human activity at the site and restore the geographical background of the ethnic minority regimes who lived in the coastal areas of south China during the Eastern Zhou dynasty and the related influence on regional civilisation. Dating results suggest that the site was built during the Spring and Autumn and Warring States periods (3.2–2.4 thousand years ago), which can reasonably explain the presence of relics from the Warring States period on and within the wall. Our dating results are also consistent with the late Neolithic stone tools and pottery fragments found in the area, suggesting that the site was an ideal settlement before castles were constructed. Based on the spatial distribution of the Neolithic sites and Holocene transgression records in the Fuzhou Basin, it was found that coastline advance and retreat were the main factors affecting the paleo-human activity in the Fuzhou Basin during the late Neolithic period. Previous studies showed that the seawater gradually withdrew from the basin around 2 ka BP. Before this, humans mainly lived in the crescent-shaped area on the west side of the Fuzhou Basin, close to the ancient coastline. Based on existing archaeological results and chronological data, it can be shown that the lower reaches of the Minjiang River, where Fujian Province's capital is located, has long been the centre of ancient human activity in the coastal areas of south China, with a civilisation history of 6–4 ka and a city construction history of at least 2.9 ka.

Impacts of Transboundary Transport on Coastal Air Quality of South China

AbstractTransboundary transport plays an important role in air pollution formation in China. The coastal area of south China (CA‐SCHN) frequently experiences air pollution in spring and autumn, but the contribution of transboundary transport to the air quality is still not clear. Meteorological field analyses reveal that large‐scale synoptic patterns over east China in spring and autumn provide favorable situations facilitating southward transport of air pollutants originated from the North China Plain (NCP) and Yangtze River Delta (YRD). A springtime case study using the WRF‐Chem model shows that trans‐boundary transport of air pollutants from the NCP and YRD contributes to 27% and 46% of ozone (O3) and fine particulate matter (PM2.5) concentrations in the CA‐SCHN, respectively. In the autumn case, the contribution is around 11% for O3 and 24% for PM2.5. In the spring, air pollutants in the NCP and YRD are transported over seas by large‐scale synoptic systems to the South China Sea and re‐circulated by the sea breeze to the CA‐SCHN during daytime. In the autumn, the transport is driven by northerly winds over the land induced by large‐scale synoptic systems, and is also modulated by the local mountain‐valley breeze circulation. The results provide support for design and implementation of air pollutants control strategies in the CA‐SCHN.

Prediction of Aerosol Extinction Coefficient in Coastal Areas of South China Based on Attention-BiLSTM

The aerosol extinction coefficient (AEC) characterises the attenuation of the light propagating in a turbid medium with suspended particles. Therefore, it is of great significance to carry out AEC prediction research using state-of-art neural network (NN) methods. The attention mechanism (AM) has become an indispensable part of NNs that focuses on input weight assignment. Traditional AM is used in time steps to help generate the outputs. To select important features of meteorological parameters (MP) that are helpful for forecasting, in this study, we apply AM to features instead of time steps. Then we propose a bidirectional long short-term memory (BiLSTM) NN based on AM to predict the AEC. The proposed method can remember information twice (i.e., forward and backward), which can provide more context for AEC forecasting. Finally, an in situ measured MP dataset is applied in the proposed model, which presents Maoming coastal area’s atmospheric conditions in November 2020. The experimental results show that the model proposed in this paper has higher accuracy compared with traditional NN, providing a novel solution to the AEC prediction problem for the current studies of marine aerosol.

A Comprehensive Correlation Study of Structured Soils in Coastal Area of South China about Structural Characteristics

Granite residual soil is a common engineering material, and its mechanical properties are of great importance to engineering safety. This kind of soil presents obvious structural characteristics, and many researchers have emphasized the significance of its structural features. According to previous experiments, from a macroscopic perspective, many researchers have investigated the structural relationship between undisturbed and remolded soils, but few studies have considered it in the mesoscopic aspect. Adopting DEM (a mesomechanical simulation method), we can study how the structure affects the mechanical process between undisturbed and remolded soil. Therefore, this paper combines DEM with laboratory tests to study the structural characteristic correlation between undisturbed and remolded soil. The results indicate that a weak cohesion effect exists in undisturbed soil, and the damage of weak cohesion elements accompanies the failure process. Weak cohesion elements in undisturbed soil cause inhomogeneities in deformation, stress state, and damage accumulation, which ultimately causes differences in strength curves. This paper explains the mechanism of the structural effect on mechanical evolution from a mesomechanical perspective. The DEM simulation method proposed in this paper can be applied to structured soils and better guide engineering practice.

The dynamics of the fishing fleet in China Seas: A glimpse through AIS monitoring

Monitoring fishing activities is crucial for marine conservation but challenging in practice, because the ability in tracking fisheries has been limited on varying spatial and temporal scales. The challenge is for both developed and developing countries, and is outstanding in China which is characterized by the world's largest fishing fleet. The advance of Automatic Identification System (AIS) provides the opportunity to enforce monitoring and to promote the compliance of responsible fisheries. Here, the dynamics of fishing fleets in China Seas were integrally investigated for the first time. We demonstrated heavy fishing efforts widely distributed across China Seas, whereas most vessels were concentrated along the coastal line. The temporal pattern of fishing efforts was dominated by summer moratorium, and intensive fishing occurred immediately before and after the moratorium. We highlight that most fishing activities occurred in a remarkably limited spatial and temporal scope, particularly trawling vessels which spent a few months on fishing every year and covered a small geographical area. Additionally, considerable fishing efforts have transferred from Eastern China Sea to the coastal areas of south China in response to an extension of summer moratorium, which requires the fishing moratorium beginning one month earlier since 2017. We argue that summer moratorium cannot effectively control overall fishing efforts, but rearrange the same level of efforts in space and time. We highlight caveats in the interpretation of AIS data in terms of reception issues, meanwhile the novel information provided by AIS can refine the understanding of fleet dynamics and contribute to adaptive fisheries management over broad spatial and temporal scales.