Pearl River Delta Region Research Articles

Application feasibility of the novel SWAM Water-Cycle and Allocation Model in the Guangdong-Hong Kong-Macao Greater Bay Area

At present, there are still problems, such as uneven regional distribution and low per capita ownership of water resources in the Pearl River Delta, so solving the problem of water resource allocation is still a hot spot that needs continuous attention in the region today. For a long time, many experts and scholars have proposed models such as WEAP (Water Resources Assessment and Planning) and SWAT (Soil and Water Assessment Tool). Based on the advantages and disadvantages of the current situation of water resource allocation in China, this paper explores and analyzes the applicability of the newly proposed SWAM (SWAM Water-Cycle and Allocation Model) configuration model, compares the previously proposed model, and finally draws conclusions. In this work, the author analyzes the adaptability of SWAM model in the Pearl River Delta region from various aspects and concludes that the SWAM model can effectively alleviate the problems of water resources in the Pearl River Delta region.

Spatio-temporal heterogeneity of transportation carbon emissions and its driving factors in China’s main urban agglomerations

The transportation sector in China has the characteristics of large total carbon emissions, high level, and unbalanced spatial distribution. For carbon emissions reduction, it is of great significance to study the carbon emissions of transportation in China in different regions. Focusing on China’s three urban agglomerations: Beijing-Tianjin-Hebei Region, Yangtze River Delta Region and Pearl River Delta Region, this paper explores and compares the spatio-temporal heterogeneity of China’s traffic carbon emissions from 2000 to 2019 by using methods such as GWR and ESDA. The results show that: 1) As for carbon emissions, the total carbon emissions and per capita carbon emissions of the three urban agglomerations have shown a significant growth trend. The high-value aggregation in Beijing-Tianjin-Hebei Region has weakened, the high-value and low-value aggregation in the Yangtze River Delta Region has increased, and the change in the Pearl River Delta Region is not obvious. 2) As for influencing factors, motor vehicle ownership has the greatest impact on regional carbon emissions, but the impact intensity of motor vehicle ownership on carbon emissions of the three urban agglomerations is different. 3) As for spatio-temporal heterogeneity, after 2010, the spatial correlation of carbon emissions of the three urban agglomerations was lower than that of the surrounding areas, and all of them were weakened.

National industrial investment fund and China's integrated circuit industry technology innovation

Since the emergence of information technology, the integrated circuit industry has been a major contributor to sustained economic expansion. This paper proposes a theoretical model premised on the pertinent theories of technological progress in late-mover countries and concludes that it is challenging for late-mover countries to rely solely on market mechanisms to elevate the level of social technology; state policy support is indispensable. In addition, this paper employs the panel data of 81 A-share listed integrated circuit companies in China from 2011 to 2019 and implements the Difference in differences (DID) method to evaluate the impact of the National Integrated Circuit Industry Investment Fund on the technological innovation of the integrated circuit industry, and adopts the double-difference propensity score matching method for supplemental verification. This paper concludes that the National Integrated Circuit Industry Investment Fund has significantly enhanced industrial technological innovation and that the estimated results premised on the difference-in-difference based on propensity score matching (PSM-DID) method and the placebo test are not substantially differentiated from the benchmark regression results. The effects of industrial investment funds on policy are evidently different across different regions and industry chains, in accordance with research on industry heterogeneity. The promotion effect of the core link is significantly stronger than the support link in terms of branches of the industrial chain, and the Pearl River Delta region has a more pronounced promotion effect in terms of regions. Verification of the mechanism demonstrates that industrial investment funds can relieve corporate financing constraints, optimize corporate human capital structure, promote corporate RandD (research and development) investment, and subsequently promote technological innovation in the integrated circuit industry through the aforementioned three effects. On the one hand, the research presented in this paper offers empirical support and policy guidance for the implementation of technological innovation in China's integrated circuit industry. On the other hand, it also has significant reference value for fostering the growth of industrial investment funds.

Elucidating the Factors Governing the Interannual Variability of Ozone Concentrations During Fall 2015-2019 in Sanya, China

While ozone pollution has been a major air pollution concern in metropolitans in China, the characteristics and governing factors of ozone concentrations in Sanya remains unclear. In this study, we first analyze the interannual variability of ozone based on observational data in Sanya, and identify it is in general characterized by a peak ozone season in fall and minimal ozone season in summer. Meanwhile, the substantial ozone enhancement in 2019 compared to the previous three to four years over Sanya clearly stands out. To elucidate the possible governing factors, we design a few numerical experiments based on regional air quality model, and find that the modulation of meteorology is key to steering the interannual variability of ozone in fall in Sanya. The spatial evolution further indicates that the transport from upwind regions like Pearl River Delta region is crucial in stimulating the ozone accumulation in Sanya. In addition, ship emissions play important roles in further enhancing their ozone concentration, ranging from 7% -10% during 2015-2019. The findings in this study imply that whereas an overall low ozone concentration in Sanya, ozone exceedance may still occur in particular under unfavorable meteorological conditions together with the concomitant transport from other regions facing ozone pollution. It stresses the importance of regional emission control, including anthropogenic emissions and ship emissions, on improving air quality in Sanya.

A Study on the Coordinated Development of Population Growth and Social Security in Guangdong Province

This study aims to analyze the coordinated development of population growth and social security in Guangdong Province, and summarize the objective laws of development in various economic regions. The research aims to provide new insights for the government to promote the coordinated development of population growth and social security based on local conditions, formulate sustainable social security policies, improve the level of social security in Guangdong Province, and enrich the content of social security policy reform. The research methods include literature review, exploration of advanced theories and models from abroad, and processing of publicly available data from the Guangdong Provincial Government in 2020. Additionally, the study utilizes the principles of statistical measurement of variable coupling to calculate the coordination between population development and social security development in Guangdong Province, and explains the differences in coordination levels among different regions through empirical research methods.The results indicate a significant positive correlation between population development and social security development in most regions of Guangdong Province. Regions with higher levels of population development tend to have higher levels of social security, and there is a similar spatial distribution pattern between the two. However, there is also a significant imbalance in development among different regions. Based on the coordination level between population development and social security development, the Pearl River Delta region is categorized as having high-quality coordination, the mountainous areas are classified as moderately imbalanced, and the western and eastern regions are deemed severely imbalanced. In conclusion, data analysis suggests that the Guangdong Provincial Government needs to further deepen the reform of the social security system, promote economic integration, strengthen the construction of social security institutions, narrow the wealth gap between regions in Guangdong Province, maintain coordinated development among different regions, promote further economic development in Guangdong, attract more talent to stay in the province, and achieve the goal of shared economic development for all citizens.

Differential soil acidification caused by parent materials and land‐use changes in the Pearl River Delta region

AbstractSoil acidification occurs widely across the world, which has been partly attributed to land‐use change. However, measureable effect of land‐use change as well as parent materials on soil acidification remains poorly understood. Here, a typical area with intensive land‐use change in the Pearl River Delta of China was chosen for this study. Topsoil (0–20 cm) and subsoil (20–40 cm) samples (n = 169) under different land uses (paddy fields, vegetable lands and orchards) and parent materials (granite and alluvial sediment) were collected in 2020. Soil pH, exchangeable base cations, exchangeable acidity and pH buffering capacity were measured to evaluate the status of soil acidification. The change of soil pH over the last 15 years was evaluated via comparing with historical data (n = 329) in 2005. The results showed a higher exchangeable acidity and lower pH buffering capacity and exchangeable base cations of soils derived from granite compared with soils derived from alluvial sediment in 2020. In the last 15 years, significant soil acidification under different parent materials was observed under vegetable lands and orchards but not paddy fields. Faster pH decline was found under land‐use change from paddy fields compared with the unchanged vegetable lands or orchards. Furthermore, stronger acidification under the same land‐use change was observed for soils derived from granite compared with soils derived from alluvial sediment. These results indicate that land‐use change induced soil acidification is dependent on parent materials. This study implies that cropping management such as suitable rotation operation may slow soil acidification, and measures including straw returning may ameliorate acidified soils.

METALANGUAGE THEORY: INTERPRETATION OF ZI-SHU-NV’S MARRIAGE BELIEF

The relevance of the study is determined by the necessity to understand the mechanisms of formation within a society of socially significant ideas, beliefs and behavioral strategies.
 The aim is to interpret the notions of marriage that existed in China’s Pearl River Delta region among Zi-Shu-Nv girls who were known for choosing not to marry.
 Materials and methods. The article deals with the semiotic approach to the analysis of Zi-Shu-Nv marriage belief in Chinese culture. This belief is interpreted as a cultural text, part of semio-sphere. The method of analysis was the interpretation of the phenomenon based on deconstruction from the perspective of metalanguage theory with a focus on contextual metalanguage, interpretive competence metalanguage and textual metalanguage.
 Results. Each metalanguage is characterized by its own codes and rules. The article underlines the role of each metalanguage in the origin and development of Zi-Shu-NVs’ marriage belief. The authors come to the conclusion that this belief is an inevitable outcome under the influence of social, personal and textual peculiarities of its time.
 Practical implications. The results can be used in the interpretation of social phenomena in modern society.

The Impacts of Urban Environments on Community Trust of the Low-Income Group: A Case Study for the Pearl River Delta Region

Under the burgeoning development of urbanization in China, the low-income groups have received attention recently. By applying a linear regression model and utilizing the date from the 2016 China Labor-force Dynamics Survey, this study has explored the effects of urban environments on the community trust in low-income groups, paying particular attention to the difference between local residents and migrants in the Pearl River Delta (PRD). The empirical findings suggest the following: (1) community trust in low-income groups is influenced by social environment dimension, urban space dimension, and sociodemographic characteristics. Specifically, urbanization rate, population density, POl density, land development intensity, social contact, self-rated health, and age have significant effects on the community trust of low-income groups. (2) For local residents, social environment dimension (social contact), urban space dimension (urbanization rate), and sociodemographic characteristics (political status, hukou status, age, and self-rated health) have significant effects on community trust. (3) In the case of migrants, only the sociodemographic characteristics (working in private enterprises or organizations and in agriculture) have a significant impact on community trust. According to the empirical results, the optimization of physical space and social space should consider low-income groups’ needs in livable community planning.

Refined Carbon Emission Measurement Based on NPP-VIIRS Nighttime Light Data: A Case Study of the Pearl River Delta Region, China.

The accurate measurement of CO2 emissions is helpful for realizing the goals of "carbon neutralization" and "carbon peak". However, most current research on CO2 emission measurements utilizes the traditional energy balance coefficient and top-down methods. The data granularity is large, and most studies are concentrated at the national, provincial, municipal, or district/county administrative unit scale. As an important part of the Guangdong-Hong Kong-Macao Greater Bay Area of China, the Pearl River Delta region has good nighttime light vitality and faces huge carbon emission pressure. Using the Pearl River Delta as the research area, this study constructed an optimized pixel-scale regression model based on NPP-VIIRS (The Visible Infrared Imaging Radiometer Suite on the Suomi National Polar-Orbiting Partnership spacecraft) nighttime light data and CO2 emissions data at the district and county levels for 2017. In addition, the spatial pattern of CO2 emissions in the Pearl River Delta was analyzed based on the predicted CO2 emission status. The results showed that the spatial pattern of CO2 emissions in the Pearl River Delta had the distinct characteristics of the "center-edge" effect, the spatial spillover effect, and high-value aggregation, which should be considered when making related social or public decisions.

Occurrence and risks of 23 tire additives and their transformation products in an urban water system

Tire wear particles (TWPs) enter road surface with the friction between tires and road surfaces. Under the volatilization, leaching, and transformation action on TWPs by sunlight and rain, tire additives are released into urban water systems, such as surface rainfall runoff, wastewater treatment plants (WWTPs), receiving surface waters, and drinking water treatment plant (DWTP). In this study, we investigated the occurrence of 23 tire additives and their transformation products in the urban water system of the Pearl River Delta region, South China. Nineteen target compounds were detected in the surface runoff, with 1,3-Diphenylguanidine (DPG) showing highest maximum concentration of 58780 ng/L. Benzothiazole and its transformation products are detected at the frequency of 100 % with the total concentrations of 480–42160 ng/L. The antioxidant derivative N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-Q) was also detected up to 1562 ng/L, which was considerably higher than that of the parent compound 6PPD (the maximum concentration of 7.52 ng/L). Eleven and 8 compounds were detected in WWTPs influents and effluents, respectively, with removal rates of − 62–100 %. Seventeen compounds were detected in the receiving Zhujiang and Dongjiang rivers, while 9 compounds were detected in drinking water sources and DWTP samples. Road runoff, with total concentrations of target compounds up to 79200 ng/L, is suggested as the main non-point source for receiving rivers, while WWTPs effluents are the point sources due to incomplete removal of target compounds after accepting the initial runoff. 6PPD-Q and other 10 compounds displayed median to high ecological risks in surface waters, and the human daily intake of tire additives was estimated to be 2.63 × 10−8-3.16 × 10−5 mg/(kg d) via drinking water. This is the first report of the 6PPD-Q and 1,3-Diphenylurea levels in surface waters in China.

Evolution of the coupling coordination between the marine economy and urban resilience of major coastal cities in China

Exploring the coordinated relationship between the marine economy and urban resilience can help improve urban resilience and the quality of the marine economy. Based on panel data from 2010 to 2019 in 20 major coastal cities in China, we adopted the entropy method, coupling harmonious degree model, and Theil index to measure and calculate the interval index differences in the marine economic quality and urban resilience level. Coordination between the marine economy and urban resilience was also calculated. First, we found that the quality level of the marine economy climbed in waves, forming a spatial distribution pattern that was highest in the Circum–Bohai Sea Region, followed by the Yangtze River Delta Region and the Pearl River Delta Region, and lowest in the Urban Agglomeration in the West Coast, and the gap between regions gradually narrowed. Second, the level of urban resilience gradually increased, and the regional differences varied greatly among cities, exhibiting a spatial distribution pattern that was high in the center and low in the surrounding area. Third, the coordination between the marine economy and urban resilience steadily increased, forming a spatial distribution pattern that was high in the Circum–Bohai Sea Region and Yangtze River Delta Region, and low in the Pearl River Delta Region and Urban Agglomeration in the West Coast. Fourth, the coordination gap between the regional and intra-regional marine economy and urban resilience was reduced, and the coordination between regional marine economy and urban resilience changed from two-level differentiation to diversification.

Source apportionment of PM2.5 using PMF combined online bulk and single-particle measurements: Contribution of fireworks and biomass burning

Fireworks (FW) could significantly worsen air quality in short term during celebrations. Due to similar tracers with biomass burning (BB), the fast and precise qualification of FW and BB is still challenging. In this study, online bulk and single-particle measurements were combined to investigate the contributions of FW and BB to the overall mass concentrations of PM2.5 and specific chemical species by positive matrix factorization (PMF) during the Chinese New Year in Hong Kong in February 2013. With combined information, fresh/aged FW (abundant 140K2NO3+ and 213K3SO4+ formed from 113K2Cl+ discharged by fresh FW) can be extracted from the fresh/aged BB sources, in addition to the Second Aerosol, Vehicles + Road Dust, and Sea Salt factors. The contributions of FW and BB were investigated during three high particle matter episodes influenced by the pollution transported from the Pearl River Delta region. The fresh BB/FW contributed 39.2% and 19.6% to PM2.5 during the Lunar Chinese New Year case. However, the contributions of aged FW/BB enhanced in the last two episodes due to the aging process, evidenced by high contributions from secondary aerosols. Generally, the fresh BB/FW showed more significant contributions to nitrate (35.1% and 15.0%, respectively) compared with sulfate (25.1% and 5.9%, respectively) and OC (14.8% and 11.1%, respectively) on average. In comparison, the aged FW contributed more to sulfate (13.4%). Overall, combining online bulk and single-particle measurement data can combine both instruments’ advantages and provide a new perspective for applying source apportionment of aerosols using PMF.

A Comparative Analysis of Characteristics and Synoptic Backgrounds of Extreme Heat Events over Two Urban Agglomerations in Southeast China

Based on high-resolution surface observation and reanalysis data, this paper analyzes the extreme heat events (EHEs) over two densely populated urban agglomerations in southeast China, namely the Yangtze River Delta (YRD) and the Pearl River Delta (PRD), including the spatial–temporal distribution of heatwaves and warm nights and the synoptic backgrounds for regional heatwaves. The results show that the occurrence frequency of EHEs is modulated significantly by local underlying features (i.e., land–sea contrast, terrain), and the strong nocturnal urban heat island effects make warm nights much more likely to occur in cities than rural areas during heatwaves. About 80% of the YRD regional heatwaves occur from 15 July to 15 August, while a lower fraction (53%) of the PRD heatwaves is found during this mid-summer period, which partially explains the warm-season average intensity of the former being 2–3 times the latter. A persistent, profound subtropical high is the dominant synoptic system responsible for the mid-summer YRD heatwaves, which forces significant descending motion leading to long-duration sunny weather. The mid-summer PRD heatwaves involve both high-pressure systems and tropical cyclones (TCs). A TC is present to the east of the PRD region on most (about 72%) PRD heatwave days. The organized northerly winds in the planetary boundary layer in the outer circulation of the TC transport the inland warm air, which is heated by the foehn effect at the lee side of the Nanling Mountains and possibly also the surface sensible heat flux, towards the PRD region, leading to the occurrence of the extremely high temperatures.

Localized urban canopy model and improved anthropogenic heat parameters in the weather research and forecasting model: Simulation of a warm-sector heavy rainfall event over the pearl river delta urban agglomeration

Warm-sector heavy rainfall in South China is a frequent type of precipitation in summer in the Pearl River Delta region. The complexity of the mechanisms involved in the triggering of convection, especially the effects of urbanization, has greatly increased the uncertainty of numerical simulations of warm-sector heavy rainfall. In this study, five new surface parameters with five new anthropogenic heat (AH) parameters were constructed and coupled with the urban canopy model (UCM) of the Weather Research and Forecasting model, version 4.1, based on the local climate zone system over the Pearl River Delta Urban Agglomeration (PRDUA). Taking a typical warm-sector heavy rainfall process that occurred in the PRDUA on 20 April 2019 as an example, five groups of experiments involving different schemes were compared and analyzed, revealing that the precipitation simulated using the localized UCM with the new AH parameters was the best (closest to observations). The localized UCM successfully simulated the increase in 2 m temperature and sensible heat flux and the resultant thermal forcing in urban areas, which promoted the convergence of low-level southerly winds with water vapor and the lifting of the lower-layer warm and humid water vapor to the upper layers in the urban center, leading to a significant increase of precipitation. The improved AH parameters enhanced the anthropogenic heat and its vertical conduction in urban areas, but contributed only marginally to the convergence of 10 m winds. Compared with observations from wind profile radar, it was found that the localized UCM enhanced the accuracy of the simulated horizontal wind field convergence at upper and lower levels, while the improved AH parameters enhanced the accuracy of the simulated low-level jet intensity and vertical movement, which are important drivers for the spatial variation in warm-sector heavy rainfall over the PRDUA. The current findings will be helpful for improving the model skill in simulating warm-sector heavy rainfall over high-density urban areas, as well as enhancing understanding of the impact mechanism of urbanization on the occurrence and development of warm-sector heavy rainfall.

The Industrial Sprawl in China from 2010 to 2019: A Multi-Level Spatial Analysis Based on Urban Scaling Law.

Studying the spatial-temporal distribution industrial sprawl in China is important to solve industrial sprawl problems and promote urban sustainable development. This paper constructed a multi-level spatial analysis of the Chinese industrial sprawl during 2010-2019 by mainly using urban scaling law, supplemented by GIS methods. Results showed that: (1) China had obvious industrial sprawl with a growth rate of 31.79%, reaching 2762.37 km2 between 2010 and 2019. (2) There was a stronger industrial sprawl in large cities with a larger population according to urban scaling law, especially in the East. (3) The industrial sprawl was mainly concentrated in the cities in the Northeast, Beijing-Tianjin-Hebei region, Shandong Peninsula, Yangtze River Delta region, Pearl River Delta region, Middle Yangtze River region, Fujian Province, and some cities in the West. (4) The gravity center of industrial sprawl generally moved southwest and distributed in Hubei Province. This study provided references for improving the efficiency of industrial land use and promoting high-quality urban development.

Polycyclic Aromatic Hydrocarbons Pollution Characteristics in Agricultural Soils of the Pearl River Delta Region, China.

In order to investigate the pollution status of polycyclic aromatic hydrocarbons (PAHs) in the agricultural soil, 240 agricultural soil topsoil samples were collected from nine Pearl River Delta cities from June to September 2019. In addition, 72 samples were collected for vertical soil profiles, which soil profiles were excavated to a depth of 80 cm. After sample preparation, GC-MS was used for the separation of compounds on a HP-5MS quartz capillary column. ArcGIS software was used to map the spatial distribution. Health risk assessment was conducted using USEPA standard. The results showed that the total concentration of 16 PAHs ranged from 43.4 to 5630 ng/g, with an average of 219 ng/g. The spatial distribution showed that most of the seriously polluted areas were in the coastal area, near the port, and there was point source pollution in the Gaoming of Foshan. Vertically distributed display Zhuhai, Jiangmen, Zhaoqing, Shenzhen and Dongguan increased and then decreased from bottom to bottom, showing a low-high-low pattern, the concentration of PAHs in Zhongshan and Foshan decreased with the soil depth, while the concentration of PAHs in Guangzhou and Huizhou was enriched with human activities. The PAHs components in soil samples were mainly medium and high rings (4−6 rings). The analysis of the origin of PAH in soil samples showed that the mixture of incomplete combustion sources of fossil fuels such as coal and biomass and traffic emission sources were the main sources of soil PAHs. A small amount can be attributed to oil sources such as oil spills. The human health risk assessment showed no cancer risk for children, while for adults, may cause a potential risk of cancer, which needs to be noticed. Spearman correlation analysis showed that PAH content was significantly correlated with SOC (p < 0.01) and pH (p < 0.05). Port transport, road emissions and industrial production make the area a pollution hot topic, and supervision should be strengthened to protect the environment and food safety.

Is not workplace gossip bad? The effect of positive workplace gossip on employee innovative behavior.

The purpose of this study is to examine the role of positive workplace gossip (PWG) in employee innovative behavior, whereby a mediating effect of employee loyalty is proposed in this relationship. The moderating effect of organizational trust (OT) is also examined on the indirect of PWG on employee innovative behavior through employee loyalty. This research used a survey data of 327 employees from the enterprises selected from the Pearl River and Yangtze River Delta region of China. Based on the literature review, five main hypotheses were formulated and explored. The SPSS-Process Macro Plugin was used to analyze the hypothesized model. Results show there is a positive and significant relationship between PWG and employee innovative behavior. This study also confirm that employee loyalty is an intervening variable and OT as a moderator. Organizations should pay more attention to workplace gossip phenomena, encourage employees to take appropriate part in positive workplace gossip and to communicate positive information about other colleagues, and build an inclusive, open, sincere, and interdependent platform in the organization. Employee innovative behavior plays an essential role in organization's survival and development. Few studies have investigated PWG may promote employee innovative behavior through employee loyalty. The data, model, and findings of this research address the gap and complement the current state of knowledge.

On the Prevention and Control of Public Security and the Modernization Construction of Police Organizational form in the Pearl River Delta

With the deepening development of the Guangdong-Hong Kong-Macao Greater Bay Area, the water security situation is becoming increasingly tense and causing frequent illegal and criminal incidents on the water, which has brought great harm to the economy and people's lives in the Bay Area. On the surface of the public security analysis, the public security organs to the importance of the water police is the direct reason of the deterioration of the water security situation. The deep factors include the existing problems in the form of police organization form in the Pearl River Delta, the lack of police talents in foreign-related waters, the formation of mass prevention and mass governance network by unrelated people, the urgent need of water-related laws, and the fuzzy police organization form in water waters. The prevention and control of public security in waters should start from strengthening the legal standardization and unity construction of water area public security law enforcement, developing the academic education of water area police officers, cultivating professional water area police talents and strengthening the joint prevention and cooperation mechanism of public security in the Pearl River Delta region.

Novel insights into the spatial genetic patterns of the finless porpoise from East to Southeast Asia

Several cetacean species are endemically distributed throughout the Indo-Pacific. Due to disproportionate sampling and research efforts across the Indo-Pacific region, the spatial genetic structure of these species remains poorly understood. This has led to poor phylogeographic knowledge and ambiguous taxonomic classification of many Indo-Pacific cetacean species. Of these, the finless porpoise (genus Neophocaena) is a small cetacean obligatory to the inshore waters from East Asia to the Persian Gulf of the Indian Ocean. To date, two species are generally recognized: the narrow-ridged finless porpoise inhabiting temperate and subtropical waters, and wide-ridged finless porpoises inhabiting subtropical and tropical waters. Early research efforts focused on the temperate waters off the northern China. However, recent studies have proposed that the primary divergence within the genus may lie between the Indian Ocean and Pacific region, which remains to be tested with more samples from tropical and subtropical regions. Here, we examined the genetic relationship among the finless porpoises from the Gulf of Thailand to the Taiwan Strait using both mitochondrial and autosomal markers. Bayesian assignment analysis suggested a minimum of four genetic populations within the study areas, corresponding to the narrow-ridged finless porpoise from the Taiwan Strait (TWSn), and the three wide-ridged finless porpoise populations from the Taiwan Strait (TWSw), Pearl River Delta region (PRDw), and the Gulf of Thailand (Thaiw), respectively. The minimum spanning network of the mtDNA control region found shared haplotypes among finless porpoises in Chinese waters, but those from the Gulf of Thailand formed a unique matriline lineage. Consistently, the genetic differentiation or divergence within the South China Sea (Thaiw vs. PRDw) appears to be higher than that of most finless porpoise populations examined to date, and meets the threshold values of species or sub-species level proposed for the cetacean species. The Mantel test detected a strong correlation between the geographic and genetic matrices within the South China Sea (r ​> ​0.99, p ​< ​0.001), indicating that the divergence associated with isolation-by-distance (IBD) has been accumulating in recent history. Our results imply that the formation and maintenance of the spatial genetic pattern of the finless porpoise is more complex than previously thought. However, this cannot be addressed by the current taxonomic classification of the genus.

The Influence of Synoptic Weather Patterns on Spatiotemporal Characteristics of Ozone Pollution Across Pearl River Delta of Southern China

AbstractTropospheric ozone (O3) pollution is becoming the primary obstacle to the improvement of air quality in China, especially in the Pearl River Delta (PRD) region. Because O3 pollution episodes are closely related to synoptic weather patterns (SWPs), historical episodes (from 2006 to 2019) were classified according to SWPs using the Lamb‐Jenkinson method. Monitoring network and weather reanalysis data, emission inventories, and satellite retrievals were used to investigate the spatiotemporal characteristics and influences of O3 pollution. It was found that easterly (P_E), anticyclone (P_A), and typhoon‐related (P_NE) SWPs accounted for 75% of all O3 pollution episodes. In the PRD, the O3 formation mechanism showed clear differences under different SWPs, which were affected by local emissions under P_A, whereas regional transmission dominated under P_E and P_NE. The O3 peak concentration was strongly associated with temperature, solar radiation, and shifting of the sea‐land breeze. A delayed shift of land to sea breeze caused by SWPs often caused the O3 peak to appear in the late afternoon. Finally, stepwise regression was used to explain individual meteorological parameters contributing to O3 formation. It was found that the formation of O3 pollution under P_E and P_NE was associated with increases in temperature and radiation, while P_A was mainly affected by the increase of the overnight accumulation of O3. This study advances our knowledge of the formation mechanism of O3 pollution and provides scientific support for effective O3 pollution control.