Southeast Coast Of China Research Articles

Do environmental factors affect the male frequency of exotic mangrove species Laguncularia racemosa (Combretaceae) along the southeast coast of China?

The exotic mangrove species Laguncularia racemosa (Combretaceae) is fast-growing and was used for forestation in recent years along the southeast coast of China. The breeding system of L. racemosa is variable among populations, such as hermaphroditism, gynodioecy, and androdioecy. To determine whether androdioecy is widespread in L. racemosa, 19 planted populations were surveyed along the southeast coast of China. To determine whether local environmental factors could affect the sex ratio in androdioecious populations, the observed male frequency of different populations was compared to local average annual temperature, rainfall, and salinity. The results showed that the 19 L. racemosa populations along the southeast coast of China were androdioecious. The male frequencies of these populations varied from 31.0 to 88.9%. Partial correlation analysis showed that average annual salinity explained 74.7% of the male frequency (p = 0.001). It is reasonable to note that the male frequency followed a general trend, presenting peak that coincided with the low salinity. The average annual rainfall explained only 30.4% of the male frequency (p = 0.403). And the average annual temperature explained only 20.2% of the male frequency (p = 0.206). The variable male frequency in different androdioecious L. racemosa populations may presumably be caused by ecological or genetical processes; these hypotheses will be tested in future studies.

Dynamic assessment of island ecological security under urbanization: a case study of Pingtan Island in the Southeast Coast of China

The ecological security status of Pingtan Island (PI) from 2005 to 2011 is evaluated dynamically. Results show that the ecological status of PI is increasing, and the quality of its environment is constantly optimized, especially during 2009–2012. Principal component analysis is used to analyze the driving forces of the ecological security of PI. The driving force, status, and response of PI determine its ecological security. The effect was evident in 2011. The trend of principal component synthetic score is consistent with that of the ecological security dynamic map of PI. This study can enrich the empirical case and the relevant theoretical system of environment assessment in the island. Meanwhile, it can provide reference for the evaluation methods of ecological security status of the same kind of islands at home and abroad as well as the optimal control policies.

Molecular characterization of Na+/K+/2Cl- cotransporter 1 alpha from Trachinotus ovatus (Linnaeus, 1758) and its expression responses to acute salinity stress.

Trachinotus ovatus is widely cultured in the ponds and gulf on the southeast coast of China. The dramatic salinity decrease caused by heavy rainfall could cause mass mortality of T. ovatus in aquaculture. It is very important to understand the osmoregulatory mechanism of T. ovatus. Na+/K+/2Cl- cotransporter 1a (NKCC1a) is involved in the osmoregulation of fish and plays a crucial role in cell volume homeostasis and maintenance of the electrolyte content. In this study, we characterized nkcc1a (designed as Tonkcc1a) from T. ovatus and investigated its expression responses to acute salinity changes. Tonkcc1a is approximately 70 kb in length and contains 26 exons and 25 introns. The phylogenetic analysis confirmed that ToNKCC1a belonged to the NKCC1a subclade. Quantitative real-time (qRT-PCR) analysis indicated that Tonkcc1a was ubiquitously expressed in all examined tissues, with the highest mRNA levels observed in gills, and the lowest level in liver. When T. ovatus were transferred from seawater (30‰) into fresh water, the expression levels of Tonkcc1a mRNA were significantly downregulated in gills and kidney, whereas its expression level was markedly upregulated in intestine. When transferred from seawater (30‰) to 10‰ sea water, the expression levels of Tonkcc1a mRNA were clearly increased in gills and kidney. When transferred from seawater (30‰) to 20‰ sea water, the expression of Tonkcc1a mRNA increased to some extent in gills, kidney, and intestine. When transferred from seawater (30‰) to 40‰ sea water, the expression levels of Tonkcc1a mRNA were dramatically upregulated in gills and intestine compared to that in the control. These results suggested that Tonkcc1a was involved in the response to acute salinity changes.

An Observational Study of the Diurnal Variation of Precipitation over Hong Kong and the Underlying Processes

AbstractHourly rainfall from automatic weather stations and reanalysis data from MERRA-2 are used to investigate the diurnal variation of precipitation in Hong Kong, a site along the southeast China coast with strong interactions between the monsoonal circulation and the land–sea breeze. The precipitation in Hong Kong is characterized by a spatially uniform diurnal cycle with the peak at about 0800 local time (LT), with rather weak dependence on local terrain. Precipitation unrelated to tropical cyclones (TCs) dominates the diurnal variation of precipitation, especially in the summer. The diurnal cycle exhibits a notable seasonal dependence, with the strongest signal in the summer. The morning peak of precipitation over Hong Kong is coincident with deep rising motion, linking to near-surface convergence and overlying weak divergence. The convergence may be attributed to the prevalence of the southerly monsoonal flow over the South China Sea (SCS) and to the northerly land breeze induced by the land–sea thermal contrast in the morning. The overlying weak divergence could be ascribed to the nocturnal–early morning acceleration of southerly flow over southeast China. Linked to the inverse relationship between monsoon intensity and the land–sea thermal contrast, the diurnal cycle of precipitation is strengthened when the SCS monsoon is active and weakened when the land–sea thermal contrast is high. Both the cloud-top radiative cooling effect and the enhanced radiative cooling over inland cloud-free areas also play roles in the development of the morning rainfall peak over Hong Kong.

Tropical Cyclonic Rainfall in China: Changing Properties, Seasonality, and Causes

AbstractUsing daily rainfall data from 1936 stations across China, this study investigated tropical cyclonic rainfall (TCR) changes during 1960–2014. The possible reasons behind TCR changes were examined using tracks and frequency of tropical cyclones (TCs) in both space and time. The highest annual TCR occur in coastal regions of east and southeast China (>500 mm/year). At monthly scale, August TCR can reach 150–250 mm in coastal regions. From the contribution viewpoint, TCR accounts for more than 40% of the monthly total rainfall and extreme rainfall events along the southeast coast of China. The contributions of TCR to the monthly rainfall amount decrease rapidly from coast to inland and are even faster for contributions of TCR to extreme rainfall. The distance inland from the shoreline with 250 km has been identified as the threshold, within that these contributions abruptly increase with decreasing distance from shoreline, and vice versa. In terms of extreme rainfall regimes, logistic and Poisson regressive techniques were used to identify the connections between TC‐induced extreme rainfall and El Niño–Southern Oscillation. Both these two regressions reveal that TC‐induced extreme rainfall tends to occur with higher frequency and magnitude in southeastern China (east and northeast coast of China) during La Niña (El Niño) years (El Niño). These consistent relations and remarkable spatial patterns can help to predict the occurrence of TC‐induced extreme rainfall events across eastern China.

Heavy metal exposure has adverse effects on the growth and development of preschool children.

The purpose of this study was to investigate the associations between levels of lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn) in the PM2.5 and blood and physical growth, and development parameters including birth length and weight, height, weight, body mass index (BMI), head circumference, and chest circumference in preschool children from Guiyu (e-waste exposure area) and Haojiang (the reference area). A total of 470 preschool children from Guiyu and Haojiang located in southeast coast of China were recruited and required to undergo physical examination and blood tests during the study period. Birth length and weight were obtained by birth records and questionnaire. Pb and Cd in both PM2.5 and blood were significantly higher in Guiyu than Haojiang. Remarkably, the children of Guiyu had significantly lower birth weight and length, BMI, and chest circumference when compare to their peers from the reference area (all p value < 0.05). Spearman correlation analyses showed that blood Pb was negatively correlated with height (r = -0.130, p < 0.001), weight (r = -0.169, p < 0.001), BMI (r = -0.100, p < 0.05), head circumference (r = -0.095, p < 0.05), and chest circumference (r = -0.112, p < 0.05). After adjustment for the potential confounders in further linear regression analyses, blood Pb was negatively associated with height (β = -0.066, p < 0.05), weight (β = -0.119, p < 0.001), head circumference (β = -0.123, p < 0.01), and chest circumference (β = -0.104, p < 0.05), respectively. No significant association between blood Cd, Cr, or Mn was found with any of our developmental outcomes. Taken together, lead exposure limits or delays the growth and development of preschool children.

Evaluating land ecological security and examining its relationships with driving factors using GIS and generalized additive model

Land ecological security (LES) refers to the environmental health and sustainability of the land resources and ecosystems, which are substantially affected by biophysical and socio-economic factors. We assess the spatiotemporal patterns of LES in Ningbo city on the southeast coast of China from 1975 to 2015 and explore the effects of driving factors. Expert evaluation is used to estimate the LES score for each 2×2km grid and map the patterns by Kriging. Five levels of LES are used: very secure, secure, neutral, insecure and very insecure. A generalized additive model (GAM) captures the relationships between LES and driving factors, and identifies the dominant factors. Our results show that the Ningbo LES has been deteriorating since 1975, and it is now very insecure in Ningbo city center and the central area of the satellite city Cixi. The dominant factors affecting LES are distances to city center (Dcity), district center (Ddistrict) and road networks (Droads), and the moving window built-up area (Dndbi). Among these, Dndbi is most important as inferred by the highest explained deviance of the GAM. This study improves our understanding of the spatiotemporal patterns of LES in Ningbo and how LES changes. As a result, it provides insight to help local governments optimize land-use configuration, potentially improving the environment and ecosystems and creating a more environmentally friendly city.

Structure and dynamics of microbiomes associated with the marine sponge Tedania sp. during its life cycle

Tedania sp. is a dominant sponge that is ubiquitous along the southeast coast of China. High-throughput sequencing and transmission electron microscopy were used to describe a detailed profile of sponge-associated microbiomes at seven life stages: adult, embryo-containing spawning adult, embryo, pre-competent larva at 2h and 4h, competent larva at 8h and post-larva within 1-2h after settlement, as well as the surrounding seawater. Among a total of 15098 operational taxonomic units (OTUs), 13 were present exclusively in all stages of the sponge life cycle and could thus be identified as sponge-specific bacteria. Many OTUs were shared between the sponge and seawater, though abundance differed. The relative abundance of β-Proteobacteria associated with sponges was much higher than found in seawater. The microbiomes from each life stage also exhibited a characteristic distribution. Synechococcales dominated in adults, and Enterobacteriaceae was prominent in larvae. The competent larva was notable, with sharp increases in the total OTUs, diversity indices, richness estimates and unique OTUs. Some bacterial groups that were rare in other sponge stages and seawater, such as Clostridia (5.6%), were markedly more abundant in competent larvae. In conclusion, this work greatly advances our understanding of the dynamics and persistence of the sponge-microbe association.

Impact of ENSO on typhoon wind hazard in the coast of southeast China

The typhoon wind hazard along the southeast coast of China impacted by El Nino-Southern Oscillation (ENSO) is investigated using an improved statistical dynamics track model of tropical cyclones. Three types of years (El Nino/La Nina/Neutral) during ENSO cycles are confirmed on the basis of Nino 3.4 index averaged from July to October. It is found that the tropical cyclone genesis positions and tracks varied significantly in the three types of years, which turns to influence the passing rates and extreme wind speeds in the coastal areas of southeast China. During El Nino years, the passing rates and extreme wind speeds are lower than the other two types of years obviously. Moreover, the impact of ENSO on typhoon wind hazard of southeast China in different time horizons is examined by considering the variation of frequencies of the three types of years in different time windows. The interannual passing rates and extreme wind speeds vary remarkably; however, the multi-decadal remains more or less unchanged. This suggests that it is worthy of consideration of the variation of typhoon wind hazard posed by ENSO in interannual horizon or return period, while less or not for that of the wind hazard in multi-decadal horizon.

Review: Micro-organic contaminants in groundwater in China

Micro-organic contaminants (MOs) in groundwater, which may have adverse effects on human health and ecosystems worldwide, are gaining increased attention in China. A great deal of research has been conducted to investigate their sources, occurrences and behavior in aquifers. This paper reviews the main sources, distribution, concentrations and behavior of a wide range of MOs in groundwater in China. These MOs include well-established persistent organic pollutants—polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), endocrine disrupting chemicals (poly brominated diphenyl ethers (PBDEs), phthalic acid esters (PAEs), bisphenol A (BPA)—and some contaminants of emerging concern such as pharmaceutical and personal care products (antibiotics, caffeine, shampoos) and perfluorinated compounds (PFCs). The results reveal that the main MOs in groundwater are PAHs, organochlorine pesticides (OCPs), PBDEs, PAEs, and antibiotics. Moreover, some PFCs such as perfluorobutane sulfonic acid (PFBS), perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) have only recently been observed in groundwater as emerging organic contaminants. Additionally, most MOs are distributed in populated and industrialized areas such as the southeast coast of China. Finally, industrial emissions, wastewater treatment plant effluents and agricultural wastewater are found to be dominant sources of MOs in groundwater. Based on the existing pollution levels, regulation and amelioration of MOs are warranted.

EPR-RCGA-based modelling of compression index and RMSE-AIC-BIC-based model selection for Chinese marine clays and their engineering application

The compression index is a key parameter in the field of soft clay engineering. In this paper, we propose an improved method for correlating the compression index with the physical properties of intact Chinese marine clays that are involved in many construction projects in coastal regions in China. First, the compression index and some common physical properties of clays from 21 regions along the Chinese coast are extracted from the literature. Then, a basic regression analysis for the compression index using the natural water content and Atterberg limits is conducted. To improve the correlation performance, an evolutionary polynomial regression (EPR) and real coded genetic algorithm (RCGA) combined technique is adopted to formulate different equations involving different numbers of variables. An optimal correlation using only natural water content and liquid limit as input parameters is finally selected according to the root mean square error (RMSE), Akaike’s information criterion (AIC), and Bayesian information criterion (BIC). The proposed correlation is evaluated and shown to perform better than existing empirical correlations in predicting the compression index for all selected Chinese marine clays. This correlation is validated to be reliable and applicable to engineering applications through the prediction of the properties of an embankment on the southeast coast of China using finite element method. All comparisons show that the EPR and RCGA combined technique is powerful for correlating the compression index with the physical properties of the clay, and that model selection by RMSE, AIC, and BIC is effective. The proposed correlation could be used to update current formulations, and is applicable to engineering design in coastal regions of China.

Effects of temperature on the survival, feeding, and growth of pearl gentian grouper (female Epinephelus fuscoguttatus × male Epinephelus lanceolatus)

Pearl gentian grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) is an important commercial and economic fish from the southeast coast of China. Yet, the optimal water temperature for the aquaculture of pearl gentian grouper has not been reported in China. The present study compared the survival, feeding, and growth parameters of pearl gentian groupers (121.62 ± 10.08 g) cultured at six different water temperatures (9, 14, 19, 24, 29, and 34 °C) for 30 days. The results showed that the survival rate of pearl gentian groupers increased with increasing water temperature. When the temperature was equal to or lower than 14 °C, all the fishes stopped eating and all died within 18 days. At 29 and 34 °C, the survival rate was 100%. The feeding rate and the daily weight gain increased with elevated water temperature, with the maximal value observed at 34 °C. At 29 °C, the food conversion ratio was the lowest, in comparison to treatments at other temperatures. Based on the regression curve between specific growth rate and water temperature, the optimal temperature for the growth of pearl gentian grouper was estimated to be 32.4 °C. Overall, the present results contribute basic information for the aquaculture of pearl gentian grouper in China.

Diurnal Variations of CH4 and N2O Fluxes from the Drained Aquaculture Pond in the Minjiang River Estuary During Early Winter

Annual drainage is a typical management activity practiced by operators as a way to export aquaculture effluent, accelerate aerobic decomposition of bottom soils, and avoid eutrophication during the non-culture period after harvest. Drainage activities can cause large changes in hydrology, nutrient cycling, sediment physicochemical properties, and even broad ecosystem functions. In order to understand the effects of drainage on the diurnal variation characteristics and magnitude of greenhouse gas (CH4 and N2O) fluxes from the aquaculture ponds of the estuaries, a 24-hour continuous monitoring was conducted from one undrained pond (UDP) and one drained pond (DP) during early winter in the Minjiang River estuary on the southeast coast of China. Over the entire study period, the fluxes of CH4 from the UDP and DP ranged from 0.04 to 0.10 mg·(m2·h)-1 and 14.04 to 33.72 mg·(m2·h)-1, respectively, with means of (0.07±0.01) mg·(m2·h)-1 and (24.74±2.33) mg·(m2·h)-1. The CH4 flux was lower during the day and higher at night with a net flux as the sources of the CH4. The fluxes of N2O from the UDP ranged from -0.027 to 0.011 mg·(m2·h)-1, and the average fluxes of (0.002±0.004) mg·(m2·h)-1 showed "weak absorption by day and emission at night." The N2O fluxes from the DP were emitted all day (ranging from 0.59 to 1.76 mg·(m2·h)-1) with the average fluxes of N2O (1.07±0.15) mg·(m2·h)-1 indicating higher fluxes at night and lower fluxes during the day. Our research demonstrated that drainage would significantly enhance CH4 and N2O release from the aquaculture ponds. The study also preliminarily confirms that the undrained pond converted to a drained pond considerably alter the diurnal variation characteristics of the CH4 and N2O emissions during early winter. Clearly, future measurements in situ at high frequency over a long time and at different spatial scales would be worth researching from drained aquaculture ponds.

亚热带河口陆基养虾塘水体溶解性碳浓度及沉积物-水界面碳通量时空动态特征

PDF HTML阅读 XML下载 导出引用 引用提醒 亚热带河口陆基养虾塘水体溶解性碳浓度及沉积物-水界面碳通量时空动态特征 DOI: 10.5846/stxb201702210284 作者: 作者单位: 福建师范大学,福建师范大学地理科学学院,福建师范大学地理科学学院,福建师范大学地理科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（41671088）；福建师范大学亚热带河口生物地球化学创新团队项目（IRTL1205）；福建师范大学地理科学学院研究生出国（境）访学资助计划（GY201601） Spatial-temporal variations of water column dissolved carbon concentrations and dissolved carbon flux at the sediment-water interface in the shrimp ponds from two subtropical estuaries Author: Affiliation: Fujian Normal Universities,School of Geographical Sciences, Fujian Normal University,School of Geographical Sciences, Fujian Normal University,School of Geographical Sciences, Fujian Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以福建闽江和九龙江河口陆基养虾塘为研究对象，通过野外原位观测和室内模拟培养实验，开展了河口陆基养虾塘养殖期间水体溶解性有机碳（DOC）和溶解性无机碳（DIC）及养虾塘沉积物-水界面碳交换通量变化特征的研究。结果表明：时间变化上，养虾塘水体溶解性碳浓度及沉积物-水界面碳通量在闽江河口呈现8月中旬 > 10月中旬 > 6月中旬的特征，在九龙江河口表现为随养殖阶段推移而增加的趋势；空间变化上，闽江河口养虾塘水体溶解性碳浓度及沉积物-水界面碳通量显著高于九龙江河口；沉积物释放溶解性碳速率与水体溶解性碳浓度呈现显著正相关关系，沉积物碳释放过程是引起养虾塘水体溶解性碳浓度时空变化的重要因素。表明河口区水产养虾塘碳循环研究时需考虑不同形态碳生物地球化学循环的时空差异性。 Abstract:Aquaculture ponds play an important role in the global carbon cycle. In order to understand the dynamics of carbon in the shrimp ponds, dissolved carbon (dissolved organic carbon[DOC] and dissolved inorganic carbon[DIC]) concentrations in the pond water column, and the exchange fluxes of dissolved carbon across the sediment-water interface, were investigated in the Min River estuary (MRE) and Jiulong River estuary (JRE) on the southeast coast of China. Water and sediment samples were collected using a hydrophore and sediment sampler from three shrimp ponds in June, August, and October 2015, respectively. Meanwhile, water-quality indicators (water temperature, pH, dissolved oxygen, and salinity) were measured in situ using a portable instrument. The dissolved carbon concentration in water was analyzed using a SHIMADZU TOC-VCPH/CPN analyzer. Sediment oxygen and nutrient exchange (SONE) incubation techniques were used to measure the rates of dissolved carbon fluxes. The results showed that dissolved carbon concentrations in the pond water, and fluxes across the sediment-water interface from the estuaries of shrimp ponds greatly varied in spatial and seasonal dynamics. Mean dissolved carbon concentrations and fluxes were significantly higher from the shrimp ponds in the Min River estuary than in the Jiulong River estuary (P < 0.05). Average seasonal dissolved carbon concentrations (or fluxes) in the Min River estuary and Jiulong River estuary followed the order:August > October > June and October > August > June, respectively. The variations in dissolved carbon concentrations in the water were significantly positively correlated with the dissolved carbon fluxes across the sediment-water interface, indicating that the process of dissolved carbon release in the sediment affects the dynamic variation of dissolved carbon concentrations in the water column. Overall, the dynamic variation of dissolved carbon concentrations and fluxes in the shrimp ponds could be due to the synthetic action of abiotic factors (e.g., temperature and salinity), the foraging and metabolic activity of shrimp, and feed supply. Our study highlights the need to consider the spatio-temporal difference of carbonic biogeochemical cycles to better understand the dynamic of carbon cycling from the aquaculture ecosystems in the estuaries. 参考文献 相似文献 引证文献

An idiogram on pachytene bivajents with high resalution multiple bands of Epinephelus malabaricus

Epinephelus malabaricus (Perciformes, Serranidae), a rare marine commercial fish inhabits in the warm-water reef along the southeast coast of China. In the present study, well-spread pachytene bivalents with multiple high-resolution bands were obtained after the testes were treated with a hypotonic alkaline solution and a high-chloroform fixative solution, showing that the number and characteristics of band in each bivalent were stable. According to karyotype analysis, the haploid chromosome set was n=24 (24t), and no heteromorphic bivalent was found. The relative length of the longest and shortest bivalent were 5.86 and 1.66, and the length ratio was 3.53, which was much higher than the length ratio of the exact metaphase mitotic karyotype (1.5) and premetaphase endonuclease karyotype (1.75). An idiogram with 447 bands was constructed, and the zone of each bivalent was divided, respectively. The detailed description of the landmark system and the band positions were preliminary given. This study aims to provide a theoretical reference for the further research on cytogenetics and the physical map construction of chromosome fine frame of E. malabaricus.

Bulbophyllum yunxiaoense sp. nov. (Orchidaceae: Epidendroideae: Malaxideae) from Fujian, China: Morphological and molecular analyses

We have described and illustrated a new species, Bulbophyllum yunxiaoense (Malaxideae, Epidendroideae, Orchidaceae), from Fujian Province in southeast China. The size and overall floral morphology of the new species are similar to those of Bulbophyllum pingtungense, a species endemic to Taiwan Island on the southeast coast of China and its closest relative according to a cladistic analysis of nuclear (ITS) and plastid (matK, trnL-F, and atpI-atpH) DNA sequences. However, B. yunxiaoense is distinguishable from B. pingtungense by flower colour, shorter scape, and longer lateral sepal.

A statistical dynamics track model of tropical cyclones for assessing typhoon wind hazard in the coast of southeast China

An improved full track model for tropical cyclones (TCs) based on statistical dynamics method is developed to estimate typhoon wind hazard in the coast of southeast China. The track model includes genesis model, movement model, and intensity model. The genesis model is established based upon an improved kernel probability density function with the biased cross-validation bandwidth. The movement model is developed based on the Beta and Advection Model (BAM). The intensity model consists of an auto-regression ocean intensity model and an inland decay model using the nearest neighbor method. Using the historical environment data, 1000 years TC tracks are simulated by the improved model and compared with features of the historical tracks in the western North Pacific (WNP) basin, the results verify that the developed model performs well. Moreover, typhoon wind hazard in the coastal areas of southeast China is estimated by the improved track model combined with a parametric wind field model. Compared with the current Chinese design code, the relative differences between estimated return period velocities and those recommended in design code are less than 13.4%. The developed model enables analyzing typhoon hazard in the context of climate change, which is our future task.

Simulated Diurnal Cycles and Seasonal Variability of Low‐Level Jets in the Boundary Layer over Complex Terrain on the Coast of Southeast China

AbstractThe thermal and dynamical causes of boundary layer low‐level jets (LLJs) over the southeast coast of China (a very complex terrain) are explored using a very high resolution diagnostic model California Meteorological (CALMET) along with the Advanced Research Weather Research and Forecasting (WRF‐ARW) model, combined with observations. Both diurnal and seasonal variations in LLJs are investigated using simulations during two observational periods and four months in 2011. Two configurations, with different vertical and horizontal resolutions, are compared. The results show that the use of higher vertical and horizontal resolutions (including land cover/use) in the diagnostic model CALMET leads to large improvements in simulating boundary layer LLJs over complex terrain as compared with using lower vertical and horizontal resolutions in both WRF‐ARW and CALMET models. The simulations using the diagnostic model CALMET better reproduced the observations, in that both LLJ events occur in the night (nocturnal LLJs) and in the afternoon (afternoon LLJs) are noticed. Compared to the nocturnal LLJs, the afternoon LLJs have larger wind speeds and occur at lower heights. The afternoon LLJ characteristics are closely associated with local thermodynamic circulations including the mountain‐valley breeze and land‐ocean breeze, which are regulated by the thermal contrasts between the ocean and mountains, and diurnal cycle of boundary layer friction. A comprehensive analysis of an afternoon LLJ and nocturnal LLJ indicates that there are large differences in wind field, vertical motions, and water vapor distributions between them. The local thermodynamic circulations also strongly affect vertical motions; even under a relatively stable atmosphere, the vertical motions during LLJs are stronger than the monthly average. Afternoon LLJ events, associated with the southeasterly land‐ocean breeze in summer, occur more frequently than in winter; in contrast, nocturnal LLJ events occur in summer less frequently than in winter. The seasonal variation analysis shows that land‐ocean breezes have significant effects on the wind speed, wind direction, and heights of the afternoon LLJs; local thermal contrast forcing is believed to be the main factor that affects the LLJs during the daytime especially in warm seasons.

A Port City in Northeast China: Dengzhou in the Long Eighteenth Century

AbstractIf we were asked to recall a coastal city of early modern China, most of us would choose Shanghai, Canton, Xiamen, or Macau. These port cities became famous for facilitating trans-regional sea trade that linked the Qing Empire to the rest of the world. Attentive observers know that all of these cities are located on the Southeast China coast, by which we mean the coastal areas south of Shanghai. Taking Shanghai as the dividing line between the northeastern and southeastern coastlines, the port cities of the south are far more likely to be familiar to us than are those of the north. I consider this phenomenon (i.e. the focus on the coast of early modern China) to be a “Southeast China centrism.” And although we might all concede that some southeastern seaports were vital to transoceanic interactions, it is shortsighted to ignore the northern port cities and the role they played in connecting China with the maritime world. In this article I investigate the importance of Northeast China's port cities by focusing particular attention on the less familiar coastal seaport of Dengzhou. By detailing and examining the political and economic importance of this port city in the early modern period, I will show that Qing China's northeastern coast was no less important than the southeast. Even if China's northern port cities might not have been as economically vibrant as those in the south, we should not overlook their functions and histories. Indeed, they also attained unique patterns of political and economic development throughout the long eighteenth century.

Impact of rapid urbanization on the modern sedimentary environments in a semienclosed embayment: Tong’an Bay, southeast China coast

ABSTRACTTong’an Bay (TAB) is a semienclosed embayment in the north of Xiamen Island. The sea area of TAB was mainly used for aquaculture in enclosed areas before 2003. Since 2003, the districts surrounding TAB have been undergoing a rapid urbanization process, and the scale of land used for urban construction in these districts has been continuously increasing. Under the backdrop of rapid urbanization, the coastline of TAB has largely been transformed into an artificial coastline. Due to the large scale of land reclamation and, dredging activities and the opening of the Gaoqi-Jimei (GJ) Seawall, there have been relatively significant changes in the coastal and submarine geomorphology in central northern, western, and southern TAB and Wuyuan Bay as well as a significant increase in the area where artificial submarine geomorphologies are distributed; the number of surface sediment types in the TAB has increased, and sediments in the sea area surrounding engineering projects have been coarsening; the sediment transport pattern has not significantly changed at the mouth of TAB and in central northern TAB, but the suspended sediment transport direction near the GJ Seawall has changed to a certain extent.