Bohai Gulf Research Articles

盐胁迫对中国柽柳幼苗生理特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 盐胁迫对中国柽柳幼苗生理特性的影响 DOI: 10.5846/stxb201312182981 作者: 作者单位: 中国矿业大学(北京),滨州学院,中国矿业大学(北京),滨州学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家十二五科技支撑计划项目(2011BAC02B01); 国家自然科学基金项目(31370702, 41201023) Effects of salt stress on physiological characteristics of Tamarix chinensis Lour. seedlings Author: Affiliation: China university of mining and technology (Beijing),Binzhou university,China university of mining and technology (Beijing),Binzhou 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:以中国柽柳(Tamarix chinensis Lour.)插穗为研究材料,在装有不同土壤盐分梯度(0.4%、0.8%、1.2%、1.6%、2.0%、2.4%)的盆钵中进行扦插试验,测定柽柳扦插成活率、叶绿素含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性及丙二醛(MDA)含量等指标,研究分析柽柳扦插成活率及幼苗生理特性对盐分胁迫的响应特征。结果表明:(1)柽柳扦插成活率随盐胁迫增强逐渐降低,适合扦插繁殖的土壤含盐量低于0.8%;土壤含盐量超过0.8%后,扦插成活率太低,不适合柽柳进行扦插繁殖。(2)柽柳可通过提高叶绿素含量来适应盐胁迫,随着盐胁迫增强,柽柳扦插幼苗叶片中叶绿素含量先升高后降低,但过高的盐胁迫会破坏叶绿素的合成。(3)柽柳扦插幼苗叶片SOD和POD活性随盐胁迫增强先升高后降低,通过提高SOD和POD活性来清除细胞内多余的活性氧自由基,但活性氧自由基积累过多时,膜脂过氧化作用会破坏细胞膜的稳定性,导致抗氧化酶活性降低。(4)柽柳扦插幼苗叶片MDA含量随盐胁迫的增强先升高后降低。在土壤含盐量0.4%-1.2%范围内,MDA含量虽高于CK,但各盐分处理之间差异不显著。在含盐量为1.6%时,叶片细胞受到膜脂过氧化作用加强,MDA含量显著升高,但含盐量为2.0%时,MDA含量降低。 Abstract:Changyi National Marine Reserve lies on the south coast of Bohai Gulf, which was established to preserve the biggest Tamarix chinensis Lour. community in China. However, human over-exploitation of the underground brine caused sea-water intrusion, whereas the annual evaporation capacity gradually increased because of the global climate changes, thereby aggravating the soil salinization and degradation. The population of T. chinensis gradually degraded under the conditions of high soil osmotic pressure, poor aeration and moisture, low nutrient availability, and high soil salinity. Therefore, the effects of salt stress on the eco-physiological characteristics of T. chinensis cuttings became very important for the ecological restoration of the coastal wetlands. In this paper, we studied the effects of different salinity (0%, 0.4%, 0.8%, 1.2%, 1.6%, 2.0%, and 2.4% NaCl solutions) on the eco-physiological characteristics of T. chinensis in the greenhouse. The survival rate, chlorophyll content, activities of superoxide dismutase (SOD) and peroxidase (POD), and malondialdehyde (MDA) content were determined. The results showed that the survival rate of T. chinensis cuttings gradually decreased with increasing the salt stress. The survival rate was 100% in the control group. The difference of the survival rate between the control and the treatment with 0.4% NaCl was not significant, and the survival rate was about 80% in the treatment with 0.8% NaCl. The survival rate decreased significantly when the salinity increased to more than 0.8%. With the increased salt stress, the chlorophyll content initially increased and then decreased. We conclude that the seedlings were able to adapt to lower salt stress conditions by increasing the chlorophyll content, which was used to enhance the photosynthesis. However, the chlorophyll content decreased under higher salt stress conditions because the concentration of salt stress exceeded the threshold of the plant adaptation. The activities of SOD and POD increased and then decreased with the increasing salt stress conditions. The seedlings were able to eliminate the reactive oxygen species accumulated through the increasing activities of SOD and POD under lower salt stress conditions. With the salt stress increasing, the activities of SOD and POD decreased because the membrane lipid peroxidation damaged the stability of the cell membrane. MDA is an important indicator of injured cell membrane, and its content increased with increased salt stress conditions. The absence of significant difference between treatments with salt concentration less than 1.2% and significant increase in the content of MDA in the treatment with 1.6% NaCl solutions indicates that the seedlings were less influenced by the membrane lipid peroxidation when the salt stress was less than 1.2%. This phenomenon may be explained by the regulation of the antioxidant enzymes. 参考文献 相似文献 引证文献

MODELING THE SAILING RISK OF ROPAX SHIPS WITH BAYESIAN NETWORK

In this paper, a methodology based on Bayesian Network (BN) was proposed to deal with the difficulty of risk analysis in RoPax transport. Based on data collection and expert survey, BN model for RoPax sailing risk analysis was constructed first. Then the Expectation Maximization (EM) algorithm for parameter learning and Evidence Prepropagation Importance Sampling (EPIS) algorithm for reasoning were designed. Finally, a sensitivity analysis was conducted. To validate the model algorithms, a case study on the RoPax system of Bohai gulf in China was provided. Results indicate that the BN model can effectively address the problem of data deficiency and mutual dependency of incidents in risk analysis. It can also model the development process of unexpected hazards and provide decision support for risk mitigation.

Seasonal migration of Apolygus lucorum (Hemiptera: Miridae) over the Bohai Sea in northern China.

During the past decade, Apolygus lucorum (Meyer-Dür) has become a key pest on cotton in northern China. Whether or not this species is a migrant, and if so, what pattern of seasonal migration this species exhibits remains unknown. The combination of searchlight trapping and radar observation on an isolated island in the center of Bohai Gulf during the past 11 yr provided direct evidence that both male and female A. lucorum adults migrate at least 40-60 km (and probably much greater distances) across the Bohai Gulf waters. There were considerable yearly and monthly variation in the number of A. lucorum trapped on BH, and the migration period during 2009-2013 ranged from 102 to 154 d. A. lucorum adults had downwind displacement rather than randomly by heading toward their seasonally favorable directions, which toward the east-northeast in summer, but south-southwest (SSW) in early autumn. The vast majority of adults flying at airspeeds 0.5-2.5 m/s and at altitudes < 150 m above ground level. Most of trapped females were virgins with little or no ovarian development, as suggests that the onset of migration is initiated mainly by sexually immature individuals, which is termed the "oogenesis-flight syndrome." Such findings reveal a new route for A. lucorum movements northward to and southward from the northeastern agricultural region of China, which will help us develop more effective management strategies against this pest species.

Increasing eutrophication in the coastal seas of China from 1970 to 2050

We analyzed the potential for eutrophication in major seas around China: the Bohai Gulf, Yellow Sea and South China Sea. We model the riverine inputs of nitrogen (N), phosphorus (P) and silica (Si) to coastal seas from 1970 to 2050. Between 1970 and 2000 dissolved N and P inputs to the three seas increased by a factor of 2–5. In contrast, inputs of particulate N and P and dissolved Si, decreased due to damming of rivers. Between 2000 and 2050, the total N and P inputs increase further by 30–200%. Sewage is the dominant source of dissolved N and P in the Bohai Gulf, while agriculture is the primary source in the other seas. In the future, the ratios of Si to N and P decrease, which increases the risk of harmful algal blooms. Sewage treatment may reduce this risk in the Bohai Gulf, and agricultural management in the other seas.

Tidal flat erosion of the Huanghe River Delta due to local changes in hydrodynamic conditions

An ideal nature system for the study of post-depositional submarine mass changing under wave loading was selected in the inter-tidal platform of the subaqueous Huanghe River Delta, a delta formed during period from 1964 to 1976 as the Huanghe River discharged into the Bohai Gulf by Diaokou distributary. A road embankment constructed for petroleum recovery on the inter-tidal platform in 1995 induced the essential varieties of hydrodynamic conditions on the both sides of the road. With both sides sharing similarities in (1) initial sedimentary environment, (2) energetic wave loading, (3) differential hydrodynamic conditions in later stages, (4) enough long-range action, and (5) extreme shallow water inter-tidal platforms; the study is representative and feasible as well. Two study sites were selected on each side of the road, and a series of measurements, samplings, laboratory experiments have been carried out, including morphometry, hydrodynamic conditions, sediment properties, granularity composition, and fractal dimension calculation of the topography in the two adjacent areas. It was observed that in the outer zone, where wave loading with high magnitude prevailed, the tidal flat was bumpy and exhibited a high erosion rate and high fractal dimension. Further, the fractal dimension diminished quickly, keeping with the enlarging of calculative square size. However in the inner zone, where the hydrodynamic condition was weak, the tidal flat was flat and exhibited a low erosion rate and low fractal dimensions; the fractal dimension diminished with the enlarging of calculative square size. The fractal dimensions in the different hydrodynamic areas equalized increasingly as the calculative square size accreted to threshold, indicating that the hydrodynamic condition plays a significant role in topography construction and submarine delta erosion process. Additionally, the later differentiation of sediment properties, granularity composition, microstructure characteristics, and mineral composition induced by the different hydrodynamic conditions can also contribute to the variation of topography and sea-bed erosion in the two adjacent areas.

Does &lt;I&gt;Athetis lepigone&lt;/I&gt; Moth (Lepidoptera: Noctuidae) Take a Long-Distance Migration?

Athetis lepigone (Möschler), a new lepidopteran pest in China, has spread quickly to seven provinces since it was first reported causing damage on summer maize in Hebei province in 2005, Whether this species is a migrant or not remains unknown. The past 3 yr searchlight trapping on an island in the center of Bohai Gulf provided direct evidence that both male and female A. lepigone moths migrate across the Bohai Gulf waters in northern China because no host crops or A. lepigone larvae were found on this island. The four migration waves observed in this study represent high-altitude movements of the overwintering, first, second, and third generations of A. lepigone moths, respectively. Carbon isotope analysis showed that 1.76-5.44% of the tested A. lepigone moths originated from C4 plants, which provides additional evidence that this species is a migrant because there are no C4 plants on this small island. The 89.24-96.89% of tested A. lepigone moths originated from C3 plants were significantly higher than that from C4 plants in all generations, suggesting that maize fields are not the main host sites for A. lepigone. Few females were trapped in spring and early summer with relatively high mating frequency and more advanced ovarian development, suggesting that the migration of this species is not completely bound by the "oogenesis-flight syndrome." These findings reveal a new route for A. lepigone migrating to and from the northeastern agricultural region of China, and improve our knowledge of the migration ecology of A. lepigone. Further studies are needed to clarify the migration trajectories that will help in developing sound forecasting systems for this pest species.

Seasonal Migration of Ctenoplusia agnata (Lepidoptera: Noctuidae) Over the Bohai Sea in Northern China

Ctenoplusia agnata (Staudinger) (Lepidoptera: Noctuidae) is an important polyphagous pest in East Asia. Previous studies showed that C. agnata moths possesses the potential to undertake long-distance migration; however, knowledge of whether or not the migration of C. agnata moths is a regular ecological behavior and what the pattern of seasonal migrations is in case of regular migration is currently lacking. In the current study, systemic monitoring of population dynamics of C. agnata was conducted by a searchlight trap on an island in the center of Bohai gulf in northern China, during 2003-2013. Our results provided strong evidence for the hypothesis that C. agnata is one of the pest species undertaking regular high altitude long-distance migration and we have depicted the seasonal migration pattern over the Bohai Sea. The first capture of C. agnata generally appeared in late April and early May, then the daily number of catches increased to high levels in late July and formed two waves of migration through August and early September, and finally, the moths disappeared in late October. The mean time from the earliest trapping to the latest trapping within a year was 141.0 +/- 3.0 days. The index of ovarian development of female C. agnata showed seasonal variability and suggested that its migratory flight may be independent of the degree of ovarian development and mating status. In addition, strong migration events took place in 2003, 2004, 2008, and 2010 (annual sum of catches > 10,000). The research result from this work is helpful for understanding the occurrence regularity of C. agnata and developing an integrated pest management strategy.

Variation of soil nutrients and particle size under different vegetation types in the Yellow River Delta

The Yellow River Delta wetland, located at the southern coast of Bohai Gulf, provides important ecosystem services such as flood control, water purification, biodiversity conservation, nutrient removal and carbon sequestration, shoreline stabilization, tourism attraction and wetland products maintains in the Yellow River Delta. This study assessed how agricultural activities in a reclamation wetland changed soil pH, soil electric conductivity, soil nutrient and soil particle size as compared to natural vegetation by using a combination of field experiments and lab analysis. The vegetation type included adjacent alfalfa field (Medicago sativa), cotton field (Gossypium spp.), Chinese tamarisk shrub (Tamarix chinensis), and reed marsh (Phragmites sage). The results indicated that the soil pH was higher (pH>8) in alfalfa field and cotton field, and alfalfa field and reed marsh had significant function in reducing soil salt content, soil electric conductivity of alfalfa field at 0–30cm were 140.38±14.36, 114.48±14.36, 125.30±11.37μs/cm. The effect of different vegetation types on soil nutrient was significant (P<0.05). Soil organic matter at 0–10cm in Chinese tamarisk shrub and reed marsh was 21.66±3.82g/kg and 16.51±4.60g/kg, which was higher than that of alfalfa field (10.47±2.36g/kg) and cotton field (9.82±1.27g/kg), but soil total nitrogen content in alfalfa field was the highest, which is significantly higher than that of cotton field, Chinese tamarisk shrub and reed marsh(P<0.05), the content of soil total nitrogen at 0–10cm and 10–20cm was 7.67±0.38g/kg and 5.97±0.51g/kg, respectively, while the content of available P and available K was reversed. The difference of soil particle size between layers was not significant (P>0.05), the sand content of Chinese tamarisk shrub soils in 0–10cm was the highest, the next was alfalfa field and cotton field, and the content of silt and clay in reed marsh was higher than the others. The correlation and significant degree between soil particle size and soil nutrient was related with vegetation types, and soil organic matter was significantly positively correlated with soil silt and clay content on the alfalfa field. The results demonstrated that wetland cultivation was one of the most important factors influencing on the nutrient fate and reserves in soil, which could lead to rapid nutrient release and slow restoration through abandon cultivation. Consequently, compared with cotton field, alfalfa field is more favorable to sustainable management of wetland cultivation in the Yellow River Delta. It should be considered in wetland restoration projects planning.

The major composition of a middle–late Eocene salt lake in the Yunying depression of Jianghan Basin of Middle China based on analyses of fluid inclusions in halite

During the Cretaceous–Tertiary transition in eastern China, abundant halites formed in non-marine areas. Many continental salt deposits from inland salt lakes were formed in eastern China in faulted basins as a result of the northward movement and collision of the Indo-China Plate with the Eurasian Plate, including the Bohai Gulf Basin. However, a marine transgression versus a non-marine origin of these evaporites remains to be determined. Primary fluid inclusions trapped in halite deposits can directly record the composition of evaporated seawater or salt lake water, such as those in the Cretaceous halite in the Khorat Plateau (Laos and Thailand) area can resolve the origins of the evaporate deposits; recent fluid inclusions data in the Khorat Plateau coincide with the predicted secular variation of seawater and are comparable to other fluid inclusions in Cretaceous marine halite, indicating these fluid inclusions are directly related to a marine transgression. Our analyses in this study shows that the average K+, Mg2+, and SO42- contents are 8.8, 5.0, and 6.8g/l, respectively, in the primary fluid inclusions in halite of middle–late Eocene from the Yunying depression of China. These numbers are much less than those in the contemporary Spanish primary fluid inclusions in halite precipitated from seawater (16.4, 36.3, and 12.5g/l for K+, Mg2+, and SO42-, respectively). Furthermore, Br contents of all fluid inclusion samples in halite from the Yunying depression are lower than 2ppm (vs. 55–58ppm at the base of Spanish contemporary marine halite), and their δ37Cl values range from −0.11‰ to +2.94‰ (vs. −0.09‰ to −0.24‰ in sylvite of Spanish deposit), indicating that the compositions of the middle–late Eocene brines trapped in halite in the Yunying depression of China are very different from those derived from the contemporary seawater, and are considered to be resulted from evaporation of an inland saline lake water with little influence of seawater.

Influence of microsprinkler irrigation amount on water, soil, and pH profiles in a coastal saline soil.

Microsprinkler irrigation is a potential method to alleviate soil salinization. After conducting a homogeneous, highly saline, clayey, and coastal soil from the Bohai Gulf in northern China in a column experiment, the results show that the depth of the wetting front increased as the water amount applied increased, low-salinity and low-SAR enlarged after irrigation and water redistribution, and the soil pH increased with an increase in irrigation amount. We concluded that a water amount of 207 mm could be used to reclaim the coastal saline soil in northern China.

The competitiveness of China's Leading Regions: Benchmarking Their Knowledge‐based Economies

AbstractChina's spectacular economic growth has been spatially uneven, with much development occurring in eastern coastal areas. In particular, three metropolitan ‘super‐regions’ have become China's most competitive knowledge‐based economies, consisting of the Pearl River Delta, the Yangtze River Delta, and the Bohai Gulf Region. This paper benchmarks the competitiveness of these regions, with a view to exploring which region is best positioned to become the most dominant knowledge‐based economy over time. Through the theoretical lens of dynamic comparative advantage, it is shown that each region has hugely increased its competitiveness through improvements in the capacity to absorb and diffuse knowledge. It is further shown that due to multi‐dimensional advantages the Yangtze River Delta, incorporating the Shanghai metropolis, is best positioned to become the dominant hub of China's future knowledge economy. It is concluded that China's leading regions will require further economic policy adjustments in order to secure their future competitiveness.

Significant population genetic structure detected in the small yellow croaker Larimichthys polyactis inferred from mitochondrial control region

The population genetic structure of the small yellow croaker (Larimichthys polyactis) between China and Korea was further estimated by broad-scale sampling locations (Gulf of Bohai, Yellow Sea including Korea). One hundred and seventeen individuals from eight localities from coastal waters of China and Korea were analyzed based on mtDNA control region sequences (5′ mtDNA CR). A total of 97 polymorphic sites were checked, which defined 136 haplotypes. A pattern with high levels of haplotype diversity (h = 0.994 ± 0.002) and nucleotide diversity (л = 0.020 ± 0.010) was detected in the examined range, and the genetic diversity of Korea populations was higher than that of China populations. Population genetic structure analyses (MDS, AMOVA, Fst, Barrier) showed that significant genetic differentiation existed between China and Korea populations. The migration analysis indicated asymmetry migration also existed among populations, which was consistent with the result of population genetic structure. Using a variety of phylogenetic methods, coalescent reasoning, and molecular dating interpreted in conjunction with paleoclimateic and physiographic evidence, we inferred that the genetic make-up of extant populations of L. polyactis was shaped by Pleistocene environmental impacts on the historical demography of this species. Coalescent analyses (Neutrality tests, Mismatch distribution analysis, Bayesian skyline analyses) showed that the species along coastline of China and Korea has experienced population expansions originated in its most recent history at about 32–196 kya and 166–662 kya before present, respectively.

Composition and variation of sediment bacterial and nirS-harboring bacterial communities at representative sites of the Bohai Gulf coastal zone, China

With rapid urbanization, anthropogenic activities are increasingly influencing the natural environment of the Bohai Bay. In this study, the composition and variation of bacterial and nirS-harboring bacterial communities in the coastal zone sediments of the Bohai Gulf were analyzed using PCR-based clone libraries. A total of 95 genera were detected in the bacterial communities, with Proteobacteria (72.1%), Acidobacteria (10.5%), Firmicutes (1.7%), Bacteroidetes (1.4%), Chloroflexi (0.7%) and Planctomycetes (0.7%) being the dominated phyla. The NirS sequences were divided into nine Clusters (A-I). Canonical correlation analysis showed that the bacterial or denitrifying communities were correlated with different environmental factors, such as total organic carbon, total nitrogen, ammonium, sulfate, etc. Furthermore, bacterial communities' composition and diversity are influenced by oil exploration, sewage discharge and other anthropogenic activities in the coastal area of the Bohai Sea. Thus, this study provided useful information on further research on regional or global environmental control and restore.

Statistical Analysis on Shear Wave Velocity of Soils in Bohai Gulf

The shear wave velocity is an important parameter in the geo-seismic analysis. The corresponding database of shear wave velocity is founded by collecting and sorting out the data of superficial soil layers in Bohai Gulf. The scatter diagrams of soil shear wave velocity and depth are drawn using the software of ORIGIN. The exponential regression equation is selected by adopting the goodness-of-fit for evaluation index; the regression coefficients about shear wave velocity with depth of four categories of soils are fitted. The results show that there is a good relationship in the exponential form between the shear wave velocity and depth of superficial soil layers in Bohai Gulf. The obtained results can be directly provided a reference for the field without shear wave velocity.

The role of algal blooms in the formation of lacustrine petroleum source rocks — Evidence from Jiyang depression, Bohai Gulf Rift Basin, eastern China

Algal blooms are responsible for the laminae in the lacustrine Shahejie Formation in the Jiyang depression, one of the sub-basins of the Bohai Gulf Rift Basin in eastern China. About 65 oil fields have been discovered in this depression during the past 40years and the oil is mainly derived from three types of finely laminated lacustrine rocks of Shahejie Formation (Eocene–Oligocene). These lacustrine petroleum source rocks are oil shales, calcareous shales and calcareous laminated mudstones. Optical, SEM and BSEI analyses of these source rocks reveal that there are algal (coccoliths and dinoflagellates) laminae in the rocks. The individual algal lamina is generally composed almost wholly of one species, such as Reticulofenestra bohaiensis in coccolith laminae, and Fromea as well as Bohaidina in dinoflagellate laminae. This distribution suggests that the algal laminae formed from algal blooms in the ancient lake. Other components of source rocks included organic matter laminae, carbonate laminae and clay-rich laminae. We also discuss the sedimentation of organic matter laminae and carbonate laminae which were related to algal blooms. We conclude that the laminated lacustrine petroleum source sediment of Jiyang depression formed during episodes of algal blooms alternating with chemical and detrital sedimentation, and this represents the primary mechanism responsible for the formation of lacustrine petroleum source rocks.

First report of the genus Lysippe Malmgren, 1866 (Polychaeta: Ampharetidae) from Chinese waters

The ampharetid genus Lysippe Malmgren, 1866 is reported for the first time from Chinese waters. The identification was based on material deposited in the Marine Biological Museum of the Chinese Academy of Sciences (Qingdao). A new species, Lysippe trichobranchia sp. nov. is described. The new species is widely distributed in shallow waters of the Bohai Gulf, the Yellow Sea and the East China Sea at depths of 10-40 m.

Effects of an imbedded gravel–sand layer on reclamation of coastal saline soils under drip irrigation and on plant growth

Governmental goals for the development of new municipalities in areas of very saline soils near shorelines of the Bohai Gulf, in north China, include planting landscape trees and shrubs along streets and highways, and in parks in residential areas. The soils are saline because of the presence of shallow groundwater (45–138cm) with salinity levels of >24dSm−1. Prevention of upward water movement from the saline groundwater could be an important factor in facilitating reclamation of the soil above the water table, as well as the long-term sustainability of any reclamation that is achieved. The possibility of placing a 20-cm thick layer of gravel–sand at a depth of 80cm to block upward water movement was evaluated in a three-year field experiment conducted during 2009–2011. Soil salinity and growth of landscape plant species were measured. Irrigation water was the local deep groundwater with electrical conductivity of 1.7–2.1dSm−1 and SAR (sodium adsorption ratio) of 4.3mmolL−1. Results indicated that the extent of desalinization (the ratio of salt content leached to the initial salt content) for the imbedded gravel–sand layer (GL) was larger than that for the non-gravel–sand layer treatment (NGL). Less salt accumulated in the surface soil during winter in GL compared to NGL. The mean electrical conductivity of saturated paste extracts (ECe) were <5dSm−1 in root distribution zones (0–40cm) for NGL compared to 3dSm−1 for GL; the corresponding pH of saturated paste extracts (pHe) were 8.5 and 8.7. The influences of time, treatment and time×treatment on soil ECe and pHe were significant. At the end of the treatment, the salinity levels in root zones for both treatments were suitable for the growth of plants that were moderately sensitive to salinity (3–4dSm−1). The results provide theoretical and technological guidance for salt leaching and landscaping of highly saline lands located along the coast of the Pacific Ocean.

Characteristics of Air-Sea Fluxes Based on In Situ Observations from a Platform in the Bohai Gulf during Early Mid-August 2011

An eddy covariance system and other atmospheric and oceanic parameters were measured simultaneously from a fixed Platform-A in the Bohai Gulf during early mid-August 2011. One of the main goals of the comprehensive observation was to reveal the basic meteorological and hydrological characteristics of the Bohai Gulf. The results indicated that the diurnal characteristic curve for the air temperature (AT) was steeply unimodal, while the curve of the SST was a bimodal valley type and mainly influenced by tides with its valley value corresponding to the high water level during the observation period. Southeasterly winds dominated and the wind speed was generally lower than 8 m/s, and the atmospheric stability over the Bohai Gulf was generally unstable. The wave strength levels were generally below level 3, with a greater number of swell waves than wind waves. The latter were usually associated with more momentum transport, a larger difference between AT and SST, and less heat transport. During the observational period, the mean momentum, sensible, and latent heat turbulent fluxes were 0.21, 21.6, and 27.8 W/m2, respectively. The ratio of the mean latent and sensible turbulent fluxes was about 1.3 and much lower than that in the South China Sea during the summer.

Finite element analysis on thermal upheaval buckling of submarine burial pipelines with initial imperfection

In-service hydrocarbons must be transported at high temperature and high pressure to ease the flow and prevent the solidification of the wax fraction. The pipeline containing hot oil will expand longitudinally due to the rise in temperature. If such expansion is resisted, for example by frictional effects over a kilometer or so of pipeline, compressive axial stress will be built up in the pipe-wall. The compressive forces are often so large that they induce vertical buckling of buried pipelines, which can jeopardize the structural integrity of the pipeline. A typical initial imperfection named continuous support mode of submarine pipeline was studied. Based on this type of initial imperfection, the analytical solution of vertical thermal buckling was introduced and an elastic-plasticity finite element analysis (FEA) was developed. Both the analytical and the finite element methodology were applied to analyze a practice in Bohai Gulf, China. The analyzing results show that upheaval buckling is most likely to build up from the initial imperfection of the pipeline and the buckling temperature depends on the amplitude of initial imperfection. With the same amplitude of initial imperfection, the triggering temperature difference of upheaval buckling increases with covered depth of the pipeline, the soil strength and the friction between the pipeline and subsoil.

Temporal scaling behavior of sea-level change in Hong Kong — Multifractal temporally weighted detrended fluctuation analysis

The rise in global sea levels has been recognized by many scientists as an important global research issue. The process of sea-level change has demonstrated a complex scaling behavior in space and time. Large numbers of tide gauge stations have been built to measure sea-level change in the North Pacific Ocean, Indian Ocean, North Atlantic Ocean, and Antarctic Ocean. Extensive studies have been devoted to exploring sea-level variation in Asia concerning the Bohai Gulf (China), the Yellow Sea (China), the Mekong Delta (Thailand), and Singapore. Hong Kong, however, a mega city with a population of over 7million situated in the mouth of the Pear River Estuary in the west and the South China Sea in the east, has yet to be studied, particularly in terms of the temporal scaling behavior of sea-level change.This article presents an approach to studying the temporal scaling behavior of sea-level change over multiple time scales by analyzing the time series of sea-level change in Tai Po Kou, Tsim Bei Tsui, and Quarry Bay from the periods of 1964–2010, 1974–2010, and 1986–2010, respectively. The detection of long-range correlation and multi-fractality of sea-level change seeks answers to the following questions: (1) Is the current sea-level rise associated with and responsible for the next rise over time? (2) Does the sea-level rise have specific temporal patterns manifested by multi-scaling behaviors? and (3) Is the sea-level rise is temporally heterogeneous in the different parts of Hong Kong?Multi-fractal temporally weighted de-trended fluctuation analysis (MF-TWDFA), an extension of multi-fractal de-trended fluctuation analysis (MF-DFA), has been applied in this study to identify long-range correlation and multi-scaling behavior of the sea-level rise in Hong Kong. The experimental results show that the sea-level rise is long-range correlated and multi-fractal. The temporal patterns are heterogeneous over space. This finding implies that mechanisms associated with the local ecological environment, hydrodynamic and morphodynamic processes, and human activities might have driven a distinct sea-level rise in Hong Kong.