Nanao Island Research Articles

Quantifying and spatializing the island landsenses ecological condition using a two-dimensional model

Achieving the harmonious development of the “social-ecological” system is a crucial aspect of the global sustainable development goals. Landsenses ecology is an emerging concept that emphasizes sustainable land use planning and comprehensive management. Islands serve as ideal study areas setting for studying the landsenses ecology due to their vulnerability as ecosystems exposed to significant human activities. To assess the condition and spatial distribution of landsenses ecology, we established a quantitative evaluation framework that encompassed eight factors across two perceptions - physical and psychological. Our study focused on two islands situated in southeast China, which, despite their proximity, demonstrate remarkable differences in terms of natural and economic characteristics. The results revealed a significant spatial heterogeneity in the landsenses ecological condition on both islands. Nan'ao island (NAI) exhibited higher values for physical (0.5) and psychological (0.243) perceptions compared to Dongshan island (DSI), which was primarily attributed to varying natural environments and topographic factors. Notably, elevation and slope demonstrated strong correlations with landsenses ecological condition, acting as critical determinants of island development. Finally, using beaches as an example, we examined the impact of landsenses ecological conditions about the tourist resources of the islands. This study contributes to the development of scientifically informed urban and tourism planning processes by providing decision-makers with valuable insights.

Submesoscale eddies in eastern Guangdong identified using high-frequency radar observations

The statistical characteristics and mechanism underlying the generation of submesoscale eddies in eastern Guangdong were examined using high-frequency radar (HFR) observations of surface currents during 2019_2021. By applying the vector geometry-based (VG) eddy detection algorithm to HFR datasets, 313 submesoscale eddies with 229 cyclonic and 84 anticyclonic eddies were identified. Cyclonic eddies were significantly more common than the anticyclonic eddies, but they had similar distributions in terms of eddy lifespan and radius. The trajectories showed that the submesoscale eddies within the study area tended to move northward and westward. Submesoscale eddies revealed annual variations with decreasing cyclonic eddies and increasing anticyclonic eddies during the observation period. Submesoscale eddies displayed a remarkable spatial distribution. Most of cyclonic (anticyclonic) eddies occurred at the eastern and southeastern regions of the Huilai Headland (south of the Nanao Island). Eddy evolution was linked to the production of vorticity in a narrow layer along the headland, the injection of vorticity into the interior at the point of flow separation, and vorticity damping by bottom friction.

A SOM−RBFnn-Based Calibration Algorithm of Modeled Significant Wave Height for Nearshore Areas

In this paper, a calibration algorithm for forecasting the significant wave height (SWH) in nearshore areas is proposed, based on artificial neural networks. The algorithm has two features: first, it is based on SOM−BRFnn (self−organizing map–radial basis function neural network) to better reflect the clustering characteristics of the input parameters regarding wind and wave. In addition, the high-frequency variation part and the low-frequency variation part of SWH are separated by a threshold of 24 h to better describe the diurnal variation of SWH under the influence of tidal current. The algorithm is applied to the nearshore region of Nan-ao Island in the northeastern South China Sea. The results show that the algorithm can effectively correct the modeling results of nearshore SWH. Compared with the original outputs of the ERA5 model, the correlation coefficient is increased from 0.472 to 0.774, the root mean square error is reduced from 0.252 m to 0.103 m, and the mean relative error is reduced from 41% to 17.6%, respectively. Further analysis indicates that the frequency division is crucial in realizing the correction of the high-frequency variation of SWH. The results have reference significance for the application of wave numerical models in coastal areas.

Genetic-algorithm-based layout optimization of an offshore wind farm under real seabed terrain encountering an engineering cost model

Optimizing the layout of an offshore wind farm can increase its total energy output. However, previous studies did not consider the seabed terrain, which can affect the lengths of the turbine supporting structures and thus affect the cost of electricity (COE) of the wind farm. At present, it is not clear whether layouts that have been optimized without considering the terrain can be applied under real terrains. Consequently, this study used genetic algorithm to innovatively optimize the offshore wind farm layouts under different seabed terrains, including a real one at Nanao Island. Moreover, an engineering cost model was developed and employed to predict the initial capital costs of the wind farms. A Gaussian-based wake model was used to predict the wind fields at these wind farms. For complex terrains, when the layouts that were optimized without considering the terrain were applied, the COEs of the wind farms increased by 27.3%. For flattened terrains, they only increased by 3.8%. Thus, layout optimizations that consider the terrain are necessary for real applications. Besides, the COEs of wind farms had almost no sensitivity to the terrain if they had the same mean water depth, with a maximum difference of 4.79% between various terrains.

Effects of increased pH and inorganic carbon on growth and photosynthesis in the macroalga Gracilaria lemaneiformis (Gigartinales, Rhodophyta)

ABSTRACT The marine red macroalga Gracilaria lemaneiformis usually experiences a changing carbonate system during mariculture. Thalli of G. lemaneiformis collected from Nanao Island, Shantou, China, were cultured in six treatments, with two inorganic carbon (Ci) levels (ambient-Ci, AC; elevated-Ci, EC) and three pH levels (8.2, 9.0, and 9.4), to examine the influence of increased Ci concentrations and high seawater pH on growth and photosynthesis in this farmed algal species. The capacity to extract HCO3 − from seawater was relatively stable, as pH compensation points of G. lemaneiformis remained unchanged (9.54–9.59) in the six treatments. Relative growth rate (RGR) and net photosynthetic rate (Pn) of G. lemaneiformis showed no significant differences between treatments of AC and EC at pH 8.2. However, RGR and Pn were higher at EC than at AC at pH 9.4. In addition, RGR and Pn at AC treatments were 67% ± 12% and 76% ± 6% lower at pH 9.4 than at pH 8.2, respectively. At AC, total pigment content, effective quantum yield of PSII (Yield), and maximum relative electron transport rate (rETRm) were all lower at pH 9.4 than at 8.2. However, reductions of these parameters were significantly ameliorated when thalli of G. lemaneiformis were cultured at EC conditions. We conclude that increasing atmospheric CO2 is conducive to the aquaculture of G. lemaneiformis through the decline of pH and the concurrent increase of Ci in seawater.

Seismogenic structure in the source zone of the 1918 M7.5 NanAo earthquake in the northern South China Sea

As a typical rifted margin, the coastal region of the northern South China Sea has experienced many large crustal earthquakes in the past 400 years. For example, two destructive earthquakes with ~M7.0 in 1600 and ~M7.5 in 1918 occurred close to the NanAo Island. However, the mechanism of these earthquakes and seismotectonics of the region are still unclear. In this work we make the first study of the detailed three-dimensional crustal structure in the source zone of the 1918 NanAo earthquake (M7.5) using newly acquired wide-angle seismic reflection data. Our results show that current seismicity mostly occurred in a midcrustal low-velocity zone or its nearby high-to-low velocity transitional areas. We ascertain locations of the ENE-strike Littoral fault zone and the NW-strike Huanggangshui fault based on the seismic reflection profiles. These faults have caused a large-scale vertical dislocation of the sedimentary basement. The structure of the upper crust is very heterogeneous, containing many high or low velocity anomalies. However, the lower crustal structure is less heterogeneous, mainly characterized by low velocity mostly in the northern part of the study area and high velocity mainly in the southern part. The crust in the seismicity zone shows strong heterogeneity, reflecting highly cracked structural features possibly caused by destructive earthquakes. We infer that the midcrustal low-velocity zone and the intersection between the Littoral fault zone and the Huanggangshui fault could reflect weak structures in the crust and form a local stress buildup, which strongly affected or controlled the generation of intraplate seismicity. The 1918 NanAo earthquake very likely occurred within the current seismicity zone with a depth range of 15–25 km estimated from our tomographic images and previous geological and geophysical results.

Estimating cancer incidence based on claims data from medical insurance systems in two areas lacking cancer registries in China

SummaryBackgroundWe aimed to establish a Medical-Insurance-System-based Cancer Surveillance System (MIS-CASS) in China and evaluate the completeness and timeliness of this system through reporting cancer incidence rates using claims data in two regions in northern and southern China.MethodsWe extracted claims data from medical insurance systems in Hua County of Henan Province, and Shantou City in Guangdong Province in China from Jan 1, 2012 to Jun 30, 2019. These two regions have been considered to be high risk regions for oesophageal cancer. We developed a rigorous procedure to establish the MIS-CASS, which includes data extraction, cleaning, processing, case ascertainment, privacy protection, etc. Text-based diagnosis in conjunction with ICD-10 codes were used to determine cancer diagnosis.FindingsIn 2018, the overall age-standardised (Segi population) incidence rates (ASR World) of cancer in Hua County and Shantou City were 167·39/100,000 and 159·78/100,000 respectively. In both of these areas, lung cancer and breast cancer were the most common cancers in males and females respectively. Hua County is a high-risk region for oesophageal cancer (ASR World: 25·95/100,000), whereas Shantou City is not a high-risk region for oesophageal cancer (ASR World: 11·43/100,000). However, Nanao island had the highest incidence of oesophageal cancer among all districts and counties in Shantou (ASR World: 36·39/100,000). The age-standardised male-to-female ratio for oesophageal cancer was lower in Hua County than in Shantou (1·69 vs. 4·02). A six-month lag time was needed to report these cancer incidences for the MIS-CASS.InterpretationMIS-CASS efficiently reflects cancer burden in real-time, and has the potential to provide insight for improvement of cancer surveillance in China.FundingThe National Key R&D Program of China (2016YFC0901404), the Digestive Medical Coordinated Development Center of Beijing Municipal Administration of Hospitals (XXZ0204), the Sanming Project of Shenzhen (SZSM201612061), and the Shantou Science and Technology Bureau (190829105556145, 180918114960704).

Small-scale spatial analysis of intermediate and definitive hosts of Angiostrongylus cantonensis

BackgroundAngiostrongyliasis is a food-borne parasitic zoonosis. Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis. The life cycle of A. cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts. This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts, which are key components in the strategy for the prevention and control of angiostrongyliasis.MethodsThree villages from Nanao Island, Guangdong Province, China, were chosen as study area by stratified random sampling. The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016, with spatial correlations of the positive P. canaliculata and the infection rates analysed by ArcGIS, scan statistics, ordinary least squares (OLS) and geographically weighted regression (GWR) models.ResultsA total of 2192 P. canaliculata specimens were collected from the field, of which 1190 were randomly chosen to be examined for third-stage larvae of A. cantonensis. Seventy-two Angiostrongylus-infected snails were found, which represents a larval infection rate of 6.1% (72/1190). In total, 110 rats including 85 Rattus norvegicus, 10 R. flavipectus, one R. losea and 14 Suncus murinus were captured, and 32 individuals were positive (for adult worms), representing an infection rate of 29.1% of the definitive hosts (32/110). Worms were only found in R. norvegicus and R. flavipectus, representing a prevalence of 36.5% (31/85) and 10% (1/10), respectively in these species, but none in R. losea and S. murinus, despite testing as many as 32 of the latter species. Statistically, spatial correlation and spatial clusters in the spatial distribution of positive P. canaliculata and positive rats existed. Most of the spatial variability of the host infection rates came from spatial autocorrelation. Nine spatial clusters with respect to positive P. canaliculata were identified, but only two correlated to infection rates. The results show that corrected Akaike information criterion, R2, R2 adjusted and σ2 in the GWR model were superior to those in the OLS model.ConclusionsP. canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts, demonstrating that there was a risk of angiostrongyliasis in this region of China. The distribution of positive P. canaliculata and rats exhibited spatial correlation, and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A. cantonensis.

Isolation and characterization of a marine testosterone-degrading bacterium: Vibrio sp. N3

Steroids, including testosterone, estrone, 17β-estradiol, estriol and 17β-ethinyl estradiol, are harmful not only to the population dynamics of aquatic life forms but also to public health. In this study, a marine testosterone-degrading bacterium (strain N3) was isolated from Nanao Island in the South China Sea. In addition, the strain could also use 17β-estradiol (E2), 17β-ethinyl estradiol (EE2), estriol (E3) or cholesterol as a sole carbon source. According to the 16S rRNA gene sequence analysis, strain N3 was identified as Vibrio sp. Further characterization showed that the strain is aerobic, gram-negative, and mobile and exhibits resistance to ampicillin, carbenicillin, penicillin and spectinomycin. For enhancing its capacity of testosterone degradation, the Plackett–Burman factorial design and the central composite design were used to optimize the culture condition. Under optimal conditions, 92% of testosterone was degraded by Vibrio sp. N3 in 48h.

High temperature stress might hamper the success of sexual reproduction in Hizikia fusiformis from Shantou, China: a photosynthetic perspective

:Comparative studies of photosynthetic physiology were carried out to evaluate high light and temperature stresses in reproductive (receptacles) and vegetative (blades) tissues of fertile thalli of Hizikia fusiformis from Nanao Island, China. Receptacles had much higher rates of photosynthesis than blades, and temperature sensitivity was much higher for photosynthesis than for respiration. Both receptacles and blades survived extended exposure to 1500 μmol photons m−2 s−1; however, above 30°C, photosynthetic activity declined rapidly. Prolonged exposure to high temperature sharply depressed photosynthesis, and extended exposure to 40°C was more detrimental to photosynthesis than exposure to 30°C. Moreover, photosynthesis of receptacles was more susceptible to heat than photosynthesis in blades. Following 15 min at 40°C, receptacle photosynthesis declined to 28% of initial value and recovered to only 60% of initial value within 1 h in recovery conditions. However, after 30 min at 40°C, receptacle photosynthesis did not recover within 4 h, suggesting that the photosynthetic apparatus had suffered irreversible injury. Respiration was not affected by high temperature. Our study shows that high temperature but not high light stress might hamper sexual reproduction in H. fusiformis.

Spatial variations of b-values in the coastal area of Guangdong

We used earthquake catalogs recorded by Guangdong Seismological Network from 2008 to 2014 to resolve the spatial variations of b-values in the coastal area of Guangdong, particularly in three key research areas (Yangjiang, Heyuan, and offshore Nanao Island) with strong seismicity. Our results revealed that b-values exhibited significant spatial variations, and zones with low b-values could indicate the most likely seismogenic area of large earthquakes. We observed three clear low b-value patches in the offshore Nanao Island. We found a distinct high b-value peak at the depth of 11 km and two minimum peaks at about 14 and 7-8 km in the Yangjiang area. The overall b-values generally decrease with depth in the Heyuan area. The spatial variations of b-values reflect tectonic anomalies; that is, the 'low-high-low' distribution of b-values in the offshore Nanao Island and the Yangjiang area may indicate the anomaly of the crustal structure with a weak layer. The b-values of reservoir-induced seismicity are obviously lower than that induced by tectonism. This finding indicates that the reservoir area is generally at high stress state under the condition of high pore pressure. We inferred that large earthquakes might be prone to occur at 10-12 km depth in the offshore Nanao Island, at 12-15 km depth in the Yangjiang area, and at the lower part of the seismic activity zone in the Heyuan area. Moreover, the upstream area of the Xinfengjiang reservoir is the most likely area of future large earthquakes in the Heyuan area.

Seismogenic structures of the 2006 ML4.0 Dangan Island earthquake offshore Hong Kong

The northern margin of the South China Sea, as a typical extensional continental margin, has relatively strong intraplate seismicity. Compared with the active zones of Nanao Island, Yangjiang, and Heyuan, seismicity in the Pearl River Estuary is relatively low. However, a ML4.0 earthquake in 2006 occurred near Dangan Island (DI) offshore Hong Kong, and this site was adjacent to the source of the historical M5.8 earthquake in 1874. To reveal the seismogenic mechanism of intraplate earthquakes in DI, we systematically analyzed the structural characteristics in the source area of the 2006 DI earthquake using integrated 24-channel seismic profiles, onshore–offshore wide-angle seismic tomography, and natural earthquake parameters. We ascertained the locations of NW- and NE-trending faults in the DI sea and found that the NE-trending DI fault mainly dipped southeast at a high angle and cut through the crust with an obvious low-velocity anomaly. The NW-trending fault dipped southwest with a similar high angle. The 2006 DI earthquake was adjacent to the intersection of the NE- and NW-trending faults, which suggested that the intersection of the two faults with different strikes could provide a favorable condition for the generation and triggering of intraplate earthquakes. Crustal velocity model showed that the high-velocity anomaly was imaged in the west of DI, but a distinct entity with low-velocity anomaly in the upper crust and high-velocity anomaly in the lower crust was found in the south of DI. Both the 1874 and 2006 DI earthquakes occurred along the edge of the distinct entity. Two vertical cross-sections nearly perpendicular to the strikes of the intersecting faults revealed good spatial correlations between the 2006 DI earthquake and the low to high speed transition in the distinct entity. This result indicated that the transitional zone might be a weakly structural body that can store strain energy and release it as a brittle failure, resulting in an earthquake-prone area.

Bi-Level Programming Approach for the Optimal Allocation of Energy Storage Systems in Distribution Networks

Low-CO2-emission wind generation can alleviate the world energy crisis, but intermittent wind generation influences the reliability of power systems. Energy storage might smooth the wind power fluctuations and effectively improve system reliability. The contribution of energy storage to system reliability cannot be comprehensively assessed by the installed capacity of energy storage. The primary goal of this paper is to investigate the impact of the installed location and capacity of energy storage on power system reliability. Based on a bi-level programming approach, this paper presents a bi-level energy storage programming configuration model for energy storage capacity and location configuration. For upper-level optimization, a depth search method is utilized to obtain the optimal installed location of energy storage. For the lower-level optimization, the optimal capacity of energy storage is solved to meet the system reliability requirements. The influence of the contribution of energy storage location to system reliability is analyzed. The proposed model and method are demonstrated using the RBTS-Bus6 System and Nanao (NA) island distribution system in China. The results show the effectiveness and practicability of the proposed model and method.

MMC-HVDC Simulation and Testing Based on Real-Time Digital Simulator and Physical Control System

Real-time simulation of modular multilevel converter (MMC)-based HVDC is one of the most important and difficult technologies in the area of utility-scale power electronics research. This paper describes an efficient modeling approach for real-time simulation of MMC-HVDC. Taking advantages of the full parallel architecture of the field-programmable gate array (FPGA), more than 1500 submodules are able to be simulated in a single FPGA. The design details of the physical MMC control system are also presented. The presented MMC-HVDC real-time simulator and physical control system are successfully performed in the Nan-ao Island MMC-HVDC project, which is the world’s first three-terminal MMC-HVDC system for research on operation and fault characteristics. The results validate the accuracy of proposed approach and real-time MMC simulator.

Temperature response of photosynthetic light- and carbon-use characteristics in the red seaweed Gracilariopsis lemaneiformis (Gracilariales, Rhodophyta).

The red seaweed Gracilariopsis is an important crop extensively cultivated in China for high-quality raw agar. In the cultivation site at Nanao Island, Shantou, China, G.lemaneiformis experiences high variability in environmental conditions like seawater temperature. In this study, G.lemaneiformis was cultured at 12, 19, or 26°C for 3weeks, to examine its photosynthetic acclimation to changing temperature. Growth rates were highest in G.lemaneiformis thalli grown at 19°C, and were reduced with either decreased or increased temperature. The irradiance-saturated rate of photosynthesis (Pmax ) decreased with decreasing temperature, but increased significantly with prolonged cultivation at lower temperatures, indicating the potential for photosynthesis acclimation to lower temperature. Moreover, Pmax increased with increasing temperature (~30μmol O2 ·g(-1) FW·h(-1) at 12°C to 70μmol O2 ·g(-1) FW·h(-1) at 26°C). The irradiance compensation point for photosynthesis (Ic ) decreased significantly with increasing temperature (28μmol photons·m(-2) ·s(-1) at high temperature vs. 38μmol photons·m(-2) ·s(-1) at low temperature). Both the photosynthetic light- and carbon-use efficiencies increased with increasing growth or temperatures (from 12°C to 26°C). The results suggested that the thermal acclimation of photosynthetic performance of G.lemaneiformis would have important ecophysiological implications in sea cultivation for improving photosynthesis at low temperature and maintaining high standing biomass during summer. Ongoing climate change (increasing atmospheric CO2 and global warming) may enhance biomass production in G.lemaneiformis mariculture through the improved photosynthetic performances in response to increasing temperature.

The effects of severe carbon limitation on the green seaweed, Ulva conglobata (Chlorophyta)

Low inorganic carbon (Ci) concentrations in seawater are usually an important factor controlling photosynthesis and growth of seaweeds. The green seaweed, Ulva conglobata Kjellm, collected from a rock pool in a middle intertidal zone located at Nanao Island, Shantou, China, were cultured under low Ci level for several days, to examine the effect of severe carbon limitation on photosynthesis. The rather high pH compensation points obtained from the pH-drift experiments indicated that U. conglobata was capable of acquiring HCO3− from surrounding seawater as its Ci source for photosynthesis. However, thalli of U. conglobata cultured in Ci-starved seawater exhibited a decline of biomass, showing that the realistic photosynthetic carbon gain could not compensate for the respiratory carbon consumption in the thalli under severe Ci limitation during laboratory culture. Compared with ambient Ci conditions, the culture under severe Ci limitation significantly had an increased pigment content, but a lower maximum quantum yield and photosynthetic electron transport rate. Additionally, the maximum carbon-saturating photosynthesis rate and the apparent photosynthetic conductance of U. conglobata thalli increased in cultures with severe Ci limitation compared with ambient Ci in low N-grown thalli. The results suggest that under severe Ci limitation, U. conglobata thalli increased capacities of both light absorption processes and carbon fixation pathways.

The photosynthetic and respiratory responses to temperature and nitrogen supply in the marine green macroalga Ulva conglobata (Chlorophyta)

:Temperature effects on photosynthesis and respiration were investigated in the green macroalga, Ulva conglobata, collected from low rocky coast of Nanao Island, Shantou, China. Thalli were cultured at 15 and 25°C and at low nitrogen (LN) and high nitrogen (HN) availability. Dark respiration and light-saturating photosynthesis were measured as oxygen exchange; the characteristics of chlorophyll fluorescence were also assayed. The maximal photochemical yield (Fv/Fm) and maximum relative electron transport rates (rETRmax) remained stable with moderate fluctuations of temperature (15–30°C) in the short term. However, the values of Fv/Fm and rETRmax declined with the high temperature (≥ 35°C), and such a decline was more accentuated in 15°C- than 25°C-grown algae. Both the rates of photosynthesis and respiration were sensitive to measurement temperature, with the Q10 values being higher in 25°C-grown algae (HN) than 15°C-grown algae. It appeared that 25°C-grown algae displayed an optimum temperature (Topt) of 30°C for photosynthesis, while 15°C-grown algae exhibited the Topt of a range of 20–30°C. When measured at their respective growth temperature, the rates of photosynthesis were significant higher in 25°C- than 15°C-grown algae, while the rates of respiration were identical between 25°C- and 15°C-grown algae. Our results demonstrated that respiration displayed full acclimation; whereas, photosynthesis exhibited partial acclimation to changing growth temperatures in U. conglobata. Consequently, the balance between respiration and gross photosynthesis was re-established by changing growth temperature, with the ratio being lowered with warmer growth temperature. The results also showed that HN availability in culture significantly increased pigments and soluble protein contents and enhanced photosynthesis and respiration. We suggested that the acclimation potential of metabolisms in U. conglobata favored carbon acquisition and net carbon balance with the increasing seawater temperature resulting from climate change and/or increasing N loading from coastal eutrophication.

On summer stratification and tidal mixing in the Taiwan Strait

On continental shelves, a front that separates the sea into well-mixed and stratified zones is usually formed in warm seasons due to spatial variations of tidal mixing. In this paper, using eight years of in situ hydrographic observations, satellite images of sea surface temperature (SST) and chlorophyll-a (Chl-a) concentration, and results of a tidal model, we investigate summer stratification in the Taiwan Strait and its dependence on tidal mixing, upwelling, and river diluted water plumes. In most regions of the strait the dominant role of tidal mixing in determining the thermohaline structure is confirmed by the correlation between the two; there are some regions, however, where thermohaline structure varies in different ways owing to significant influences of upwelling and river diluted water plumes. The well-mixed regions are mainly distributed on the Taiwan Bank and in the offshore regions off the Dongshan Island, Nanao Island, and Pingtan Island, while the northern and central Taiwan Strait and the region south of the Taiwan Bank are stratified. The critical Simpson-Hunter parameter for the region is estimated to be 1.78.

Photosynthetic carbon acquisition in Sargassum henslowianum (Fucales, Phaeophyta), with special reference to the comparison between the vegetative and reproductive tissues.

The photosynthetic oxygen evolution characteristics were examined in both vegetative (blade) and sexual reproductive (receptacle) tissues of Sargassum henslowianum (Fucales, Phaeophyta) from the Shenao bay of Nanao Island, China, to establish the mechanism of photosynthetic acquisition of inorganic carbon (Ci) in this species. In natural seawater (pH 8.1, ca. 2.2 mM Ci), irradiance-saturated net photosynthetic rate (NPR) was greater by 25.3% in blade than receptacle, whereas dark respiratory rate (DR) was 2-fold higher in receptacle than blade. NPR at pH 8.1 was nearly saturated with the 2.2 mM Ci for both blade and receptacle. However, the values of the half-saturation constant for Ci were sharply increased at pH 9.0. NPR was significantly affected, but DR was remained unchanged, with the variation of the pH values in seawater. The data from the final pH value derived from the pH-drift experiments and the comparison between the measured and theoretically estimated photosynthetic rates suggested that both blade and receptacle were capable of acquiring HCO(3)(-) in seawater. The inhibitors experiments showed that a HCO(3)(-) dehydration mechanism mediated by external carbonic anhydrase activity occurred in both the blade and receptacle tissues of S. henslowianum. The proton buffer TRIS had no inhibitory effect on NPR at normal pH value in natural seawater (pH 8.1), but it significantly depressed NPR at pH 9.0. This suggested that proton transport occurred at the outside of the plasma membrane facilitated the operation of the carbon acquisition at pH 9.0. It was proposed that the strategy of photosynthetic carbon acquisition at higher pH would prevent the alga from the damage of over-excitation and photoinhibition in case of sunshine and calm water. We concluded that the blade and receptacle tissues of S. henslowianum have similar mechanism of acquisition of exogenous Ci from seawater to drive photosynthesis; yet they are differentiated more or less with the photosynthetic properties.

Heredity, diet and lifestyle as determining risk factors for the esophageal cancer on Nanao Island in Southern China

In this case-control study we evaluated contribution of environmental and genetic factors for risk of esophageal cancer (EC) by studying populations on Nanao Island (highest risk area for EC in China) and Shanwei (low risk region). Data on lifestyle, diet and family history were collected from the 166 newly diagnosed EC patients on Nanao between 2003 and 2004, from their 1450 first degree relatives and from controls on Nanao and Shanwei. Univariate and logistic regression analysis, family aggregation patterns, standardized incidence ratio (SIR), segregation ratio and heritability index were evaluated. The family cancer history was a significant risk factor for the two scenarios; Nanao cases versus Nanao controls, and Nanao controls versus Shanwei controls. Other risk factors included smoking, alcohol and fermented fish sauce. After adjusting for confounding variables, family history was independently associated with the occurrence of EC in Nanao cases versus Nanao controls. The incidence in the first degree relatives of Nanao cases was 0.86%, significantly higher than that of the public (0.12%) and SIR value was 1.44 in the first degree relatives of the 166 EC cases. The segregation ratio was 0.11 and the heritability index among first degree relatives was 40%. Our study indicates that there are steady pathogenic risk factors in the Nanao population's lifestyle but genetic factors also play an important role for EC onset.