South China Coast Research Articles

Unusually low TEX86 values in the transitional zone between Pearl River estuary and coastal South China Sea: Impact of changing archaeal community composition

TEX86, calculated based on the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs), is used worldwide for paleotemperature reconstruction in marine and lacustrine environments. Recently, however, increasing evidence showed that TEX86 could be affected by multiple environmental variables. In this study, TEX86 was calculated for core and polar GDGTs obtained from water column and surface sediments in the lower Pearl River and its estuary. Together with previously published core GDGT data from the coastal and open South China Sea (SCS), a comparison was made between TEX86-derived and satellite-based surface water temperature, which showed a TEX86-temperature minimum that is considerably lower than winter satellite temperature in the transitional zone between the Pearl River estuary and the coastal SCS. TEX86 showed significantly positive correlation with GDGT-2 and GDGT-3 in this transitional zone, indicating that they are the primary compounds for the TEX86 bias toward cooler temperature. Lipid and molecular DNA data both indicate that the variation in archaeal community composition rather than water depth or seasonality is likely the crucial factor causing the deviation of TEX86 in the transitional area. Our study has implications for studies in ancient continental margins where unusually low TEX86 temperatures may be observed in the geological record.

Recent progress of tsunami hazard mitigation in China

Since the disastrous aftermath of the 2004 Sumatra Tsunami (Indonesia) and the 2011 Tohoku Tsunami (Japan), China has made much effort to mitigate tsunami hazards. We briefly reviewed the progress of cataloguing, modeling, early warning and hazard analysis for tsunamis in China. Compiling a Chinese tsunami catalogue is a challenge at present due to a large number of inconsistent research results. In China, the numerical models widely used in engineering and related studies are developed by other countries, and the development of a domestic model is being funded by the Chinese government. The tsunami early warning system has been set up and used during the recent tsunami events, such as the Chile earthquake on February 27, 2010, and the Tohoku earthquake on March 11, 2011. Probabilistic tsunami hazard analysis (PTHA) in China has been used for the national zonation map. A test case of PTHA at Mirs Bay of South China was demonstrated. The test case supported the general view that a regional tsunami could be a great hazard to the south China coast.

Turbulence Spectra for Boundary-Layer Winds in Tropical Cyclones: A Conceptual Framework and Field Measurements at Coastlines

A conceptual model is proposed for the characteristic sub-ranges in the velocity and temperature spectra in the boundary layer of tropical cyclones (hurricanes or typhoons). The model is based on observations and computation of radial and vertical profiles of the mean flow and turbulence, and on the interpretation of eddy mechanisms determined by shear (namely roll and streak structures near the surface), convection, rotation, blocking and sheltering effects at the ground/sea surface and in internal shear layers. The significant sub-ranges, as the frequency increases, are associated with larger energy containing eddies, shear and blocking, inertial transfer between large and small scales, and intense small-scale eddies generated near the surface caused by waves, coastal roughness change, and the buoyancy force associated with the evaporation of spray droplets. These sub-ranges vary with the locations at which the spectra are measured, i.e. the level \(z\) in relation to the height \(z_{max}\) of the peak mean velocity and the depth \(h\) of the boundary layer, and the radius \(r\) in relation to the eyewall radius \(R_{ew}\) and the outer-vortex radius \(R_{ov}\). For two tropical cyclones (Nuri and Hagupit), experimental data were analyzed. Spectra were measured where \(r\) is near to \(R_{ew}\) and \(R_{ov}\) using four 1-h long datasets at coastal towers, at 10- and 60-m heights for tropical cyclone Nuri, and at 60-m height for tropical cyclone Hagupit at the south China coast. The field measurements of spectra within the boundary layer show significant sub-ranges of self-similar energy spectra (lying between the length scale 1,000 m and the smallest scales less than 40 m) that are consistent with the above conceptual model of the surface layer. However, with very high wind speeds near the eyewall, the energy of the independently generated intense surface eddy motions, associated with surface waves and water droplets in the airflow, greatly exceeds the energies of the small scales in the inertial sub-range of the boundary layer, over scales less than about 3–40 m depending on the height \(z\) and the radius \(r\). This rise in the small-scale frequency weighted spectra (\(nS_u (n)\), where \(n\) is natural frequency, and \(S_u (n)\) is the energy spectrum of the longitudinal wind component) is consistent with the hypothesis that these processes are only weakly correlated with the main boundary-layer turbulence.

Tectonics, topography, and river system transition in East Tibet: Insights from the sedimentary record in Taiwan

The Cenozoic in East Asia is marked by major changes in tectonics, landscapes, and river systems, although the timing and nature of such changes remains disputed. We investigate the geochemistry and neodymium isotope character of Cenozoic mudstones spanning the breakup unconformity in the Western Foothills of Taiwan in order to constrain erosion and drainage development in southern China during the opening of the South China Sea. The La/Lu, Eu/Eu*, Th/Sc, Th/La, Cr/Th, and εNd values in these rocks show an abrupt change between ∼31 and 25 Ma. Generally the higher εNd values in sediments deposited prior to 31 Ma indicate erosion from Phanerozoic granitic sources exposed in coastal South China, whereas the lower εNd values suggest that the main sources had evolved to inland southern China by ∼25 Ma. The SHRIMP U-Pb ages of zircons from a tuff, together with biostratigraphy data constrain the breakup unconformity to be between ∼39 and 33 Ma, suggesting that the seafloor spreading in the South China Sea commenced before ∼33 Ma. This is significantly older than most of the oceanic crust preserved in the deeper part of the basin. Diachronous westward younging of the breakup unconformities and provenance changes of basins are consistent with seafloor spreading propagating from east to west. Initial spreading of the South China Sea prior to ∼33 Ma corresponds to tectonic adjustment in East Asia, including extrusion of the Indochina block and the rotation and eastward retreat of the subducting Pacific Plate.

Carbon isotopic disequilibrium between seawater and air in the coastal Northern South China Sea over the past century

Six coastal sediment cores collected from the Northern South China Sea were dated by 210Pb and analyzed for stable carbon and oxygen isotope composition of planktonic foraminifer Globigerinoides ruber (δ13CGr and δ18OGr). Three of these cores were located east of Hainan Island and the other three off the Pearl River Estuary (PRE). Surface seawater δ18O and dissolved inorganic carbon (DIC) δ13C were identified as the dominant factors controlling downcore variations of δ18OGr and δ13CGr, respectively. Results of δ13CGr were then used to study surface water δ13CDIC and its relation to δ13C of atmospheric CO2 (δ13Catm) over the past century. Downcore records showed rather constant δ13CGr in cores off Hainan Island, but moderate decreases of δ13CGr, at rates between −0.006‰ and −0.009‰ per year, in cores off the PRE. Isotopic disequilibrium between δ13CDIC and δ13Catm was observed, with δ13CDIC apparently higher than expected at equilibrium with δ13Catm except at the site closest to the PRE. The relatively steady δ13CGr values east of Hainan Island were explained by balanced vertical mixing and biological pump, whereas the moderate δ13CGr decreases with time off the PRE were attributable to fluvial input of terrestrial carbon.

Salinity-dominated change in community structure and ecological function of Archaea from the lower Pearl River to coastal South China Sea.

Archaea have multiple roles in global biogeochemical cycles. However, we still have limited knowledge about how environmental factors affect the diversity and function of different archaeal lineages. The goal of this study was to examine the change in the abundance and community structure of Archaea in the sediments collected from the lower Pearl River (mainly North River tributary), its estuary, and coastal South China Sea (SCS) in order to evaluate how archaeal ecological function might change along the salinity gradient. Pyrosequencing of the 16S rDNA gene of Archaea was performed on sediment samples from Feilaixia Dam on the North River tributary to Wanshan islands, which have a salinity range of 0.1 to 31.2‰. Consistent with the salt tolerance of cultivated representatives, methanogens in the genera Methanoregula, Methanosaeta, and Methanosarcina and Nitrososphaera within Thaumarchaeota of the ammonia-oxidizing Archaea (AOA) were abundant in freshwater sediments of the North River tributary, whereas the marine-associated genera Methanococcoides and Nitrosopumilus were the most abundant methanogens and AOA, respectively, in the estuary and coastal SCS. However, the percentages of total methanogens decreased and Thaumarchaeota increased with salinity, respectively. The phylum Crenarchaeota was largely represented by class-level lineages with no cultivated representatives, which collectively were more abundant in the estuary and coastal SCS in comparison to freshwater sites. This study indicates that salinity is the dominating factor affecting archaeal community structure and ecological function from the North River tributary of the Pearl River, its estuary, and coastal SCS, which is consistent with salinity control on microbial diversity in other regions of the world.

Links between Libraries and Museums: a Case Study of Library-Museum Collaboration at the Hong Kong Maritime Museum

Established in 2005, the Hong Kong Maritime Museum (HKMM) is a relatively new private museum that aims to collect all forms of materials related to the development of boats, ships, maritime exploration and trade, and naval warfare on the South China coast, as well as its adjacent seas. The Museum not only serves as a unique platform for teaching and learning of the local heritage in Hong Kong, it also contributes greatly to the promotion of community engagement and social connections. The HKMM is also equipped with its own museum library, and it is called the CSSC (China State Shipbuilding Corporation) Maritime Heritage Resource Centre. In addition to supporting various research activities carried out by the Museum, this Resource Centre also serves as a central, and yet comprehensive repository for publications, and other archival documents on maritime heritage and history related to Southeastern China. This paper aims to compare the distinctive operational practices, and user needs between museums and libraries. It also examines the benefits and challenges of museum-library collaborations in the new knowledge-driven society. This paper features an interview with Kitty But (Librarian, CSSC Maritime Heritage Resource Centre, The Hong Kong Maritime Museum) and Robert Trio ( Project Officer for Technology, The Hong Kong Maritime Museum) , and in which they discussed their professional experiences in the fields of audience education; the implementation of different new technologies associated with the museum and library services; and various collaborative initiatives carried out between the Museum and the Resource Centre. Upcoming challenges and opportunities faced by both the Museum and Resource Centre are also discussed in this paper.

Hydrodynamic Response of Wave Energy Converters under Complex Sea State<sup><sup></sup></sup>

In real sea state, Ocean energy devices to work hard to stabilize, or even destroyed. Based on Airy wave theory, Movement and force of heaving cylindrical wave-energy converter (WEC) was analyzed under the complex marine state. Then setting the South China coast as the environmental background, and simulating and computing the motion response of the buoy and the mooring system under various sea conditions. The computational data show that complex mechanical response was happened and the mooring system (SM) has excellent mooring performance. The research results have practical significance for heaving cylindrical WEC survival design under real sea conditions.

Diurnal Variation of Rainfall Associated with Tropical Depression in South China and its Relationship to Land-Sea Contrast and Topography

Convective precipitation associated with tropical depression (TD) is one primary type of post-flooding season rainfall in South China (SC). Observations of the Tropical Rainfall Measuring Mission (TRMM) satellite have shown specific diurnal features of convective rainfall in South China, which is somewhat different from that in other seasons or regions of China. Convective precipitation is usually organized into a rainfall band along the southeastern coast of South China in the early morning hours. The rainfall band develops and intensifies quickly in the morning, then moves inland in the afternoon and, finally, diminishes at night. The daily convective rainfall along the coast is much more than that in the inland region, and heavy rainfall is often found along the coast. A long-duration heavy rainfall event associated with tropical depression “Fitow” during the period from 28 August to 6 September 2001, is selected in this study to explore the diurnal feature of convective rainfall and its formation mechanism. Modeling results of the 10-day heavy rainfall event are compared with both rain-gauge observation and satellite-retrieved rainfall. Total precipitation and its spatial distribution, as well as diurnal variations are reasonably simulated and agree well with observations. Further analysis reveals that the development and movement of convective precipitation is mainly related to the land and sea breezes. The anomalous height-latitudinal circulation in the morning-to-noon hours is completely reversed in the afternoon-to-late-evening hours, with the convective rainfall swinging back and forth, following its updraft branch. Sensitivity experiments show that the afternoon convective rainfall in the inland region of SC is caused by the diurnal variation of solar radiation forcing. The mountain range along the coast and the complex topography in the inland region of SC plays a critical role in the enhancement of diurnal convective rainfall everywhere. The formation of a heavy rainfall band along the southeastern coast of SC and the diurnal variation of the rainfall pattern are mainly the results of the land-sea thermal contrast.

Americans and Macao: Trade, Smuggling, and Diplomacy on the South China Coast. Edited by Paul A. Van Dyke. Hong Kong: Hong Kong University Press, 2012; distributed by Columbia University Press. ix, 251 pp. $50.00 (cloth).

Americans and Macao: Trade, Smuggling, and Diplomacy on the South China Coast. Edited by Paul A. Van Dyke. Hong Kong: Hong Kong University Press, 2012; distributed by Columbia University Press. ix, 251 pp. $50.00 (cloth). - Volume 72 Issue 4

Impacts of the East Asian monsoon on lower tropospheric ozone over coastal South China

The impact of the East Asian monsoon (EAM) on climatology and interannual variability of tropospheric ozone (O3) over the coastal South China was investigated by analyzing 11 years of ozonesonde data over Hong Kong with the aid of Lagrangian dispersion modeling of carbon monoxide and calculation of an EAM index. It was found that the seasonal cycle of O3 in the lower troposphere is highly related to the EAM over the study region. Ozone enhancements in the free troposphere are associated with the monsoon-induced transport of pollutants of continental anthropogenic and biomass burning origins. Lower tropospheric O3 levels showed high interannual variability, with an annual averaged amplitude up to 61% of averaged concentrations in the boundary layer (0–1 km altitudes) and 49% below 3 km altitude. In spring and autumn, the interannual variability in boundary layer O3 levels was predominately influenced by the EAM intensity, with high O3 mixing ratios associated with northeasterly circulation anomalies.

Microbiological Distribution of Multi-Level-well Samples in the Coast of South China

In this study, the Microbiological communities wereinvestigated by culture-independent molecular approaches. Four 16S rRNA genelibraries from mineral waterand different groundwater of wells collected from Zhuhai of the South China were constructed and analyzed by amplifiedribosomal DNA restriction analysis technique (ARDRA). The clones of dominantARDRA patterns were selected to sequence. The phylogenetic analysis indicatedthat the sequences from dominant ARDRA patterns belonged toProteobacteria, Bacteroidetes，archaea ,Actinobacteria,Planctomycetes,and Candidate division OP3, OP8, OP11et al.Thepercentages ofProteobacteriaisolated from multi-level-well samples D1,D5,D6were respectively 32.3％,34.3%,46.7%;The Bacteroidetes were respectively 5.0％,11.2％,6.5％; and Actinobacteria were respectively 5.4％,6.6％,7.8％. As a background,the seawater clone library, with the majority (32.8%) of the clones clusteringwithin theProteobacteria, the second most abundant group wereBacteroidetesandPlanctomycetes(both 9.3%), The results suggest that microbialcommunity from different vertical layers ofgroundwater in pristine habitats that have been described for the first time inChina.

Americans and Macao: Trade, Smuggling, and Diplomacy on the South China Coast

Americans and Macao: Trade, Smuggling, and Diplomacy on the South China Coast

English

  Mass mortalities among cultured postlarvae of abalone, Haliotis diversicolor supertextaLischke of between 10 and 30 days post fertilization, characterized by a white appearance and falling of the diatom films on which they grow, has occurred since 2002 on the south coast of China, including Taiwan. However, its causes remain debated. In this paper, we reported our latest findings on two different types of virus-like particles that are potentially associated with mass mortalities of postlarvae of abalone. Fourteen-day-old moribund postlarvae collected during an outbreak of postlarval disease in Shenzhen, China on November 10th, 2010 were examined by transmission electron microscopy. Besides showing severe damages in the postlarval tissues, two different types of virus-like particles were detected. These two virus-like particles were detected within both nuclei and cytoplasms of diseased abalone tissues. As they were detected in the diseased postlarval tissues, it is therefore suggested that they were potentially pathogens for postlarvae in that particular outbreak.   Key words: Postlarvae, abalone, Haliotis diversicolor supertexta, mass mortality, virus-like particles.

Influence of urban morphometric modification on regional boundary‐layer dynamics

Fidelity in simulating urban boundary‐layer (UBL) physics is recognized to prescribe the prognostic skill of subsequent regional air pollutant transport modeling. Conventional mesoscale meteorological models (MMM) deployed over the South China coast among urban locales have often yielded positive bias in surface wind speed. This bias has been hypothetically attributed to model parameterizations that yield inaccurate meteorological predictions due to underrepresentation of urban aerodynamic roughness. Chemical transport model (CTM) simulations that are forced by the overestimated UBL wind field may undergo excessive advection which results in negative bias in predicted pollutant concentration. This study aimed to corroborate the proposed causality between parameterized urban morphometry and UBL meteorology. Focus was placed on the urban meteorological adjustments induced by urban morphometry modifications rather than prediction improvements attributable to urban canopy parameterization (UCP). Case studies were devised to assess the sensitivity of an urban‐meteorology model to a pervasive, region‐wide urban morphometry modification. Performance of a UCP scheme was evaluated for the Pearl River Delta (PRD) region, a meso‐ β‐scale subtropical coastal megalopolis. To benchmark the limits of UBL adjustments that were predominantly attributable to urban morphometric transformation, numerical experiments were conducted against two urban fabrics of vastly dissimilar morphometric compositions, each occupying identical topographic tracts. Differences in the diurnal evolution of UBL structure and in the mean and turbulent flow characteristics were analyzed. This UCP sensitivity study suggests that improved urban morphological realism is able to reduce positive wind speed bias observed in conventional mesoscale meteorological models when applied to the PRD region.

Alkenone and tetraether lipids reflect different seasonal seawater temperatures in the coastal northern South China Sea

We examined the lipid-based temperature proxies U37K′ and TEX86H in five short sediment cores from the inner shelf of the northern South China Sea and related them to local sea water temperature from the World Ocean Atlas (WOA) database. The U37K′-based temperature values are consistent with euphotic zone temperature in spring and summer, when the southeast monsoon prevails and vertical stratification occurs in the water column, whereas TEX86H-based temperature values reflect sea surface temperature in winter when the northeast monsoon prevails and vertical mixing occurs. The different temperature signals between the TEX86H and U37K′ proxies could be a result of differences in the growing season between the source organisms, with alkenone-producing haptophyte algae blooming in the warmer and nutrient-rich season with higher fluvial influx, and tetraether-producing Thaumarchaeota blooming in the cooler and oligotrophic season.

Transformation of cross-boundary governance in the Greater Pearl River Delta, China: Contested geopolitics and emerging conflicts

Drawing upon the perspective of state rescaling in city-region governance, this paper explores the transformation of cross-boundary governance in the Greater Pearl River Delta (GPRD), a cross-boundary region on the South China coast consisting of the PRD under the jurisdiction of Guangdong Province, and Hong Kong and Macao Special Administrative Regions (SARs). Based on updated field investigation and in-depth interviews between 2008 and 2012, the study argues that the Greater PRD has undergone dramatic restructuring of regional governance since mid 2000s, reflected by rescaling attempts initiated by Guangdong provincial government and bottom-up resistance from local residents in Hong Kong. The interaction of the rescaling dynamics has engendered the contested geopolitics of the cross-boundary governance as the regional integration intensified. Notably, the complexity of cross-boundary governance has been heightened by emerging conflicts, resulted from the increasing number of mainlanders as ‘individual visitors’ to Hong Kong since the implementation of the Closer Economic Partnership Arrangement (CEPA), the first bilateral free trade agreement between Hong Kong and China effective from 2004. By examining the Greater PRD as a salient mega city-region, the present study enriches the growing literature on state rescaling and cross-border governance in contemporary globalization.

Emerged fossil corals on the coast of northwestern Hainan Island, China: Implications for mid-Holocene sea level change and tectonic uplift

Fossil corals are widespread on the coast of northwestern Hainan Island, China. Most of these corals are exposed during low tide levels, indicating that a higher sea level may have existed during their life time. The radiocarbon data introduced by this paper in combination with those from other sources show that the corals were alive mainly during the mid- to late-Holocene. Mid-Holocene sea levels 1–3 m higher than the present level were confirmed for adjacent coasts; however, the emerged corals on the investigated coast are not necessarily indicators of a higher eustatic sea level. They do predict relative sea levels of 1.5–3.4 m when using 1 m below the tidal datum as the upper limit of coral growth. However, using the Mean Lower Low Water as the coral’s upper growth limit, the relative sea level on the non-volcanic coast was almost as high as the present level, whereas that on the volcanic coast was 0.4–2.0 m higher than present. Therefore, the exposure of these dead coral heads and their discrepancy in elevation may be the result of tectonic uplift caused by volcanic activities. From these results, the highest sea level of upward coral growth must be defined first when using fossil corals to reconstruct past sea levels. Meanwhile, vertical tectonics have to be taken into account as a significant factor when conducting high-resolution sea level reconstruction, although the South China coast is located in a “tectonically stable” region.

Classifying El Niño Modoki I and II by Different Impacts on Rainfall in Southern China and Typhoon Tracks

Abstract Based on their opposite influences on rainfall in southern China during boreal fall, this paper classifies El Niño Modoki into two groups: El Niño Modoki I and II, which show different origins and patterns of SST anomalies. The warm SST anomalies originate in the equatorial central Pacific and subtropical northeastern Pacific for El Niño Modoki I and II, respectively. Thus, El Niño Modoki I shows a symmetric SST anomaly distribution about the equator with the maximum warming in the equatorial central Pacific, whereas El Niño Modoki II displays an asymmetric distribution with the warm SST anomalies extending from the northeastern Pacific to the equatorial central Pacific. Additionally, the warm SST anomalies in the equatorial central Pacific extend farther westward for El Niño Modoki II than for El Niño Modoki I. Similar to the canonical El Niño, El Niño Modoki I is associated with an anomalous anticyclone in the Philippine Sea that induces southwesterly wind anomalies along the south coast of China and carries the moisture for increasing rainfall in southern China. For El Niño Modoki II, an anomalous cyclone resides east of the Philippines, associated with northerly wind anomalies and a decrease in rainfall in southern China. The canonical El Niño and El Niño Modoki I are associated with a westward extension of the western North Pacific subtropical high (WNPSH), whereas El Niño Modoki II shifts the WNPSH eastward. Differing from canonical El Niño and El Niño Modoki I, El Niño Modoki II corresponds to northwesterly anomalies of the typhoon steering flow, which are unfavorable for typhoons to make landfall in China.

The Application and Trend of the FSRU for LNG Import in China

The liquefied natural gas (LNG) floating storage and regasification unit (FSRU) is a kind of LNG receiving terminal forms on the sea. Nowadays, it is the most widely used sea receiving terminal form in the engineering project as it has many advantages. In this paper, the characteristics of the FSRU were discussed based on comparing of the several LNG offshore receiving terminal. The application and trend of the FSRU in China was analyzed. It was found that FSRU is recommended for LNG import in East and South coast of China.