Fast Growth Stage Research Articles

Analysis of Gas Supply & Demand in China and Suggestions for China’s Gas Industry Development

The global natural gas markets are undergoing profound changes, with the supply and demand patterns in a historical transformation; the market supply and demand keep loose – both the gas traders and trade volume are increasing, the links between regional gas markets are enhanced, the gas pricing and trading mechanisms are diversified, the LNG trade share keeps growing, and the links between regional LNG markets are also strengthened. Influenced by the supply side reform and the accelerated urbanization, among other factors, gas consumption in China is increasing rapidly. However, the consumption of natural gas changes significantly from region to region, affected by the mismatch in gas production and consumption locations, as well as the gas import patterns. With the continuous energy restructuring in China, the gas consumption in different sectors is growing at very different paces. Analysis of the current situation, future trend and characteristics of China’s gas industry indicates that it is in the third stage of fast growth. Natural gas will play an even more important role in the future energy structure. With the continuous growth of gas consumption at home, the existing and expected gas deliverability is still faced with the risk of enlarging shortage in the mid-long term. In consideration of such circumstance, it is suggested that top-level design be strengthened on the national strategic level to seek rational, robust and scale development of the China’s gas industry. Internationally, diversified import channels should be sought to dilute supply risks, cooperation with the Asia-Pacific markets should be enhanced, and establishment of an international gas trading centre should be accelerated. Domestically, construction of a national gas interconnection system and a number of gas hubs should be speeded up, to make the gas industry an important component of the national energy network; the gas pricing mechanism should be established and completed as soon as possible to facilitate scientific allocation of profits and costs for gas production, storage and distribution, and to ultimately promote the sustainable and scale development of the whole chain of China’s gas industry.

Solid-Phase Low-Temperature Evolution of the Binary Pb–Au System: Via Contact Interactions to Intermetallic Compounds, through the Destructurization to a New Multielemental State

The paper presents the results of the long-term experiment on the solid-phase transformation of the Au–Pb metallic system which takes place at room and cryogenic temperatures. It is found that the solid-phase contact interactions between lead and gold lead to the formation of the Pb + AuPb3 eutectoid. The mass transfer and the phase formation are due to the lead extrusion along the percolation channels that form as a result of the substructural destruction of gold. No reaction layer forms at the boundary of the contacting metals. The decomposition of the solid solutions based on intermetallics AuPb3 occurs through the process of the destructurization of the material into nanoparticles, the displacement of impurity atoms from the bulk to the boundaries, the integration and ordering of separated components of the solid solution. The decomposition of the AuPb3 intermetallic compound leads to the formation of AuPb2 and the phases of variable compositions, and, then, pure components Au + Pb. The decomposition occurs through the stage of fast growth of lead crystals accompanying by the formation of loose gold nanoparticles that gradually take a faceting. The results of these studies can be useful for solution of problems of designing multicomponent metallic materials with an evolution prediction of their structure–phase transformations under the service conditions.

Multi-analysis of sheath senescence provides new insights into bamboo shoot development at the fast growth stage.

Sheath senescence is an important part of bamboo shoot development during the fast growth stage. However, no information has been reported about this distinctive process until now. Using multiple approaches, we found that sheath senescence is a complex process that occurs sequentially with chloroplast corruption, chlorophyll degradation and water loss. Reactive oxygen species (ROS), salicylic acid and abscisic acid also accumulate in the senescing sheath. Transcriptome analysis showed that NAC and WRKY transcription factors, such as NAC2 and WRKY75, as well as their possible downstream target genes, such as those involved in ROS production, proteolysis and nutrition recycling, constitute the gene network of the bamboo sheath senescence process. Furthermore, the initiation of sheath senescence might be triggered by hexokinase genes, such as HXK6, which is localized to the mitochondrion and could promote leaf senescence when overexpressed in Arabidopsis. Sheath senescence occurs after the growth decrease of the internodes, which provides assimilates. The slowing of internode growth possibly results in sugar accumulation, such as glucose, in the sheath, which finally upregulates hexokinase genes and initiates sheath senescence. These findings reveal that sheath senescence is a multilevel regulation process and has a close link to the corresponding internode growth, which provides new insights into the shoot development of bamboo during the fast growth stage.

Conditions for the occurrence of notable edge waves due to atmospheric disturbances

It has been observed and theoretically proved that edge waves can be generated by a moving atmospheric pressure disturbance near the coast. This study aims to clarify the necessary conditions for the occurrence of significant edge waves associating with moving atmospheric pressure disturbances. The complex physical problem is simplified as a pressure disturbance moving along a coast with a constant beach slope. The dominant factors include the spatial scale and translational speed of disturbance, the beach slope, as well as the transient response of water surface. The effects of each factor are discussed based on numerical modeling. It is found that the quasi-steady wave pattern is controlled by two non-dimensional parameters, the ratio of the disturbance spatial scale to the wave length of fundamental edge wave and the ratio of the disturbance spatial scale to the distance from the center of disturbance to shoreline. The duration of atmospheric disturbance or the growth time of edge wave is also found to play an important role in the occurrence of notable edge waves. Starting from a calm sea, the growth of edge wave can be divided into a fast growth stage and a quasi-steady stage. The duration of the fast growth stage is affected by the spatial scale and the beach slope. When the fundamental mode of edge wave is dominant, the appearance of a notable edge wave is affected by the translational speed and the beach slope.

Phase-field simulation on microstructure evolution of D019 phase in γ/γ′ structure of Co–Al–W superalloys

The morphological evolution and precipitation kinetics of γ′ and D019(Co3W) phase in Co–Al–W alloys at 900 °C have been studied by applying Phase-field method and experiment in order to understand the transformation process of γ′ phase and D019 phase. The growth processes of D019 phase and precipitation of γ′ phase under elastic fields were simulated through coupling with thermodynamics and dynamics databases. The simulation results indicate that the misfit δ ≥ 0.53% has a greater impact on γ′ particle morphology in γ/γ′ structure. Co–Al–W alloy with low Al and high W is one of the factors to promote the precipitation of D019 phase. Three stages during aging, namely the γ′ phase incubation stage, the γ′ phase fast nucleation and growth stage, and the transformation from γ′ phase to D019 phase stage can be observed with the non-constant coarsening rate that varying with the decrease of γ′ phase. The particle size distribution(PSD) during the precipitation of D019 phase is more in line with MLSW theory than LSW theory. This simulation results are in good agreement with the experiment results to help analyze microstructure evolution of Co–Al–W alloy.

Investigation of EOR mechanism for flue gas assisted SAGD

As a promising technique, flue gas assisted SAGD can not only reduce greenhouse gas emission but also increase economic benefits. However, the role that flue gas plays in flue gas assisted SAGD is still not very clear. Here, 2D visualization SAGD and condensation heat transfer (CHT) experiment were conducted, where temperature profiles can be measured and steam chamber can be observed simultaneously, to study systematically the effect of flue gas on SAGD performance and the EOR mechanisms of flue gas assisted SAGD. The experimental results showed the steam chamber development of flue gas assisted SAGD went through three stages: early fast growth stage, secondary upward growth stage, and slow lateral expansion stage. The injection of flue gas prolonged the high production period and increased the oil recovery by 23%. Flue gas can decrease the CHT coefficient and transform the condensation pattern from “drop condensation” to “film condensation”, which was the dominant mechanism to improve SAGD performance and the reason of the formation for secondary upward growth stage of steam chamber. Moreover, CHT coefficient decreased as flue gas water ratio increased. Besides, gas cap assisted residual oil downward and lateral expansion, as well as steam flow resistance reduction owing to gas fingering were two other crucial aspects improving SAGD performance.

Maize yield in a dryland area as affected by rainfall variability

This study aimed to report maize yield in a dryland area of North Lombok as affected by rainfall variability. A three-year study was conducted during a period of maize growing season (December to April) in 2015/2016, 2016/2017 and 2017/2018 in Gumantar village, North Lombok. Daily rainfall data was collected from a rain gauge installed in one of maize farmers’ land. Estimation of drain upper limit and crop lower limit was done based on gravimetric method. Hand-held core kits were used to collect soil samples at 0-15cm, 15-30cm, 30-60cm depth at sowing, fast vegetative growth stage (35 days after sowing=DAS), grain filling stage (85 DAS), and at harvest. Maize yield data were collected from 20 farmers that all grew maize as main crop and legume crop (ground nut or mung bean) as secondary crop. There was great rainfall variability in term of the beginning of rainy season, volume and distribution of the rain as well as the occurrence of dry-spell period resulted in great maize yield variability. The highest maize yield recorded was 8.4 ton/ha and the lowest was 0.6 ton/ha. Growing legume crop in addition to maize can be a good practice in dryland area to avoid total yield loss.

Asperity degradation characteristics of soft rock-like fractures under shearing based on acoustic emission monitoring

Shear failure of rock masses along pre-existing discontinuities is one of the predominant failure modes of rock slopes and underground tunnels. The monitoring and prediction of the impending shear failure is of great significance to ensure the stability of the rock structures and the safety of the workers. In this study, direct shear tests under normal stress ranging from 0.5 to 10 MPa are conducted on rock fractures (analogous to soft rock discontinuities), which are obtained by artificial splitting, during which the AE parameters are monitored. Test results show that the AE parameters (hit, energy and events) increase with the shear stress, and peak at or near the peak shear strength, after which the AEs gradually decay with the decrease of shear stress. The number of AE events first increases and then decreases with increasing normal stress, which may be associated with the ductile deformation of the porous structure of cement mortar under higher normal stress. The degradation of asperities on the fracture surface can be inferred from the accumulative AE hits and events, which are characterized by “S” shapes and can be divided into slow growth, fast growth and slow growth stages. Conceptual and mathematical asperity damage models are proposed respectively based on the temporal characteristics of AE events and the curve fitting, which can be used to predict the asperity damage for a given shear stress curve. The AE b-value fluctuates and remains high in the shear process. There is no strong correlation between the shear stress and the b-value, which indicates that the b-value may not be an effective index to predict the quasi-static shear failure of jointed rock masses possessing similar properties like cement mortar. Results of this study will not only contribute to a better understanding of the asperity degradation characteristics but also provide valuable knowledge for AE monitoring applications in jointed rock masses.

Characterization of the developmental dynamics of the elongation of a bamboo internode during the fast growth stage.

Previous studies on the fast growth of bamboo shoots mainly focused on the entire culm. No work about the fast elongation of a single internode, which is the basic unit for the fast growth of bamboo shoots, has been reported so far according to our knowledge. In this study, we have systematically investigated the regulating mechanisms underlying the fast growth of a single bamboo internode of Bambusa multiplex (Lour.) Raeusch. ex Schult. We discovered that the growth of the internode displays a logistic pattern, and the two sections located in the bottom of the internode, one for cell division and, another for cell elongation, each with an ~1-cm length, comprise the effective zones for the internode growth. RNA-Seq analysis identified a number of genes potentially involved in regulating the fast growth of bamboo internode such as those that have positive roles in promoting cell growth or division, which were dramatically down-regulated in the internode at fast growth decreasing stage. Further analysis revealed that sugar plays an important role in promoting the fast growth of bamboo internodes through inhibition of BmSnf1. Mechanical stress is found to be involved in the triggering of the internode growth decrease through activation of the generation of reactive oxygen species by upregulating Calmodulins. These results provide systematic insight into the biological mechanisms underlying the fast growth of bamboo shoots based on the behavior of a single internode.

Molecular Gas of the Most Massive Spiral Galaxies. I. A Case Study of NGC 5908

Abstract We present IRAM 30 m observations of molecular lines of CO and its isotopologues from the massive spiral galaxy NGC 5908 selected from the CGM-MASS sample. 12CO J = 1 − 0, 12CO J = 2 − 1, and 13CO J = 1 − 0 lines have been detected in most of the positions along the galactic disk. The total molecular gas mass of NGC 5908 is and the total cool gas mass adding atomic hydrogen is , comparable to the upper limit of the mass of the X-ray emitting hot gas in the halo. Modeling the rotation curves constructed with all three CO lines indicates that NGC 5908 has a dark matter halo mass of , putting it among the most massive isolated spiral galaxies. The 12CO/13CO J = 1 − 0, 12CO J = 2 − 1/J = 1 − 0 line ratios and the estimated molecular gas temperature all indicate normal but non-negligible star formation in this fairly gas-rich massive isolated spiral galaxy, consistent with the measured star formation intensity and surface densities. The galaxy is probably at an early evolutionary stage after a fast growth stage with mergers and/or starbursts, with plenty of leftover cool gas, relatively high SFR, low hot CGM cooling rate, and low X-ray emissivity.

Experimental Study on the Shear-Flow Coupled Behavior of Tension Fractures Under Constant Normal Stiffness Boundary Conditions

This study experimentally investigated the effects of fracture surface roughness, normal stiffness, and initial normal stress on the shear-flow behavior of rough-walled rock fractures. A series of shear-flow tests were performed on two rough fractures, under various constant normal stiffness (CNS) boundary conditions. The results showed that the CNS boundary conditions have a significant influence on the mechanical and hydraulic behaviors of fractures, during shearing. The peak shear stress shows an increasing trend with the increases in the initial normal stress and fracture roughness. The residual shear stress increases with increasing the surface roughness, normal stiffness, and initial normal stress. The dilation of fracture is restrained more significantly under high normal stiffness and initial normal stress conditions. The hydraulic tests show that the evolutions of transmissivity and hydraulic aperture exhibit a three-stage behavior, during the shear process—a slight decrease stage due to the shear contraction, a fast growth stage due to shear dilation, and a slow growth stage due to the reduction rate of the mechanical aperture increment. The transmissivity and hydraulic aperture decreased, gradually, as the normal stiffness and initial normal stress increase.

Formation and transformation of calcium phosphate phases under biologically relevant conditions: Experiments and modelling

The experimental data on calcium phosphates formation were collected in dilute solution at constant pH (7.40) and temperature (37.0 °C) at different levels of ionic strength (IS). The evolution of the solid phase formation is described in detail using a thermodynamic-kinetic model. The thermodynamic model takes into account all relevant chemical species as well as Posner’s clusters; the kinetic model, based on the discretized population balance approach, accounts for the solid formation from solution. The experimental data are consistent with an initial formation of dicalcium phosphate dihydrate (DCPD, brushite), which dominates the nucleation rate, and its rapid transformation into octacalcium phosphate (OCP) or hydroxyapatite (HA), which dominates the growth rate. Depending on the experimental conditions and, including the influence of the IS level, OCP may be further transformed into apatite. The classical nucleation theory is able to describe the experimental results very well and the solid phase growth is limited by the diffusion of Ca2+ ions. The precipitation pathway described by a complete thermodynamic-kinetic model is expected to contribute to the understating of the in vivo osteogenesis. Statement of SignificanceThe formation mechanism of calcium phosphates under biomimetic conditions is unraveled. The formation pathway is mathematically described based on a thermodynamic-kinetic model in which (i) the nucleation stages (primary and secondary) are dominated by the formation of dicalcium phosphate dihydrate (DCPD) and (ii) the fast growth stage is limited by the diffusion of Ca2+ ions under the driving force of octacalcium phosphate (OCP), or hydroxyapatite (HA), solubility. The obtained solid phase seems correlated to the activity coefficient of phosphate ions, thus to the ionic strength and local phosphate speciation. The model, being able to highlight the details of the precipitation pathway, is expected to contribute to the understanding of the apatitic phase formation in the biomineralization-biodemineralization processes under in-vivo conditions.

Dual effect of precipitation redistribution on net ecosystem CO2 exchange of a coastal wetland in the Yellow River Delta

Hydrological regime is crucial in determining the carbon dioxide (CO2) exchange between the atmosphere and wetlands. Seasonal redistribution of precipitation is one featured hydrological regime shift, but its impacts on ecosystem CO2 exchange in coastal wetlands remain unclear. Here, based on the eddy-covariance technique, we examined how the net ecosystem CO2 exchange (NEE) in a coastal wetland of Yellow River Delta in China differed between two years (2012 and 2013) with contrasting seasonal distribution of precipitation. The ecosystem absorbed more CO2 during the growing stage in 2013 (−268.5gCm−2) than 2012 (−174.7gCm−2). This difference resulted from higher NEE in the fast and middle growth stages with different reasons. In the fast growth stage, the higher mean daily NEE occurred due to more precipitation coupled with lower salt stress in 2013 (−6.3g CO2m−2day−1) compared to that in 2012 (−2.2g CO2m−2day−1). During the middle growth stage, the mean daily NEE in 2013 (−4.2g CO2m−2day−1) was significantly higher than that in 2012 (−1.1g CO2m−2day−1) because the ecosystem in 2012 suffered more waterlogged stress. This dual effect of precipitation distribution on vegetation photosynthesis was also observed in a field manipulation experiment at the same site. Our results indicated that the redistribution of precipitation among seasons would play a critical role in regulating ecosystem CO2 exchange in the coastal wetland. More research on the associated changes between dynamics of soil hydrology and salinity could promote the accuracy of the carbon-budget estimates in coastal wetlands.

Cellular and molecular characterizations of a slow-growth variant provide insights into the fast growth of bamboo.

Few studies about bamboo naturally occurring mutants have been reported so far. Using an integrated anatomy, mathematics and genomics approach, we systematically characterized the cellular and molecular basis underlying the abnormal internode development of Pseudosasa japonica var. tsutsumiana, a stable variant with dwarf and swollen internodes that are caused by the compressed spiral growth and the swollen cells in the bottom part of the internode. P. japonica var. tsutsumiana is a slow-growth variant with disorderly cell division and cell growth during the fast growth stage. Comparative transcriptome analysis identified a number of genes related to cell growth that were significantly down-regulated in the variant, including those related to auxin, vesicle transport, cytoskeleton organization and cell wall modification, consistent with the thinner cell walls and lower contents of cellulose that were found in the variant, which together with the mechanic force composed by the extrusion pressure from the neighboring fast growth cells and the weight pressure above the growing cells might finally result in the radial and irregular growth of the variant cells. This study provides key candidate genes involved in the fast growth of bamboo from a 'mutant' perspective, and supports a plausible mechanism underlying the dwarf and swollen internodes of P. japonica var. tsutsumiana.

Innovation Trends and Development Strategies in the Significant Scientific Instrument—A Case of Mass Spectrometry

Understanding innovation trends and strategies of significant scientific instrument is an important issue not only for researchers in technology development, but also for company directors for their successful management of product competitiveness. Therefore, we took mass spectrometry as case study. Multiple patent quantitative indexes and several quality indicators were introduced. The methods of patent bibliometrics, technology field analysis, technology decomposition, scenarios of growth were chose to investigate the trends for this technology. Patent layout was expressed from micro (inventors), meso (organizations), macro (countries)-three levels. The results show that key points for the research of mass spectrometry are focused on ionization and separation of mass analyzer. The application of mass spectrometry was the major area. US owned the most patents in raising the efficiency and expanding application for mass spectrometry, while Japan owned the most patents in improving reliability and convenient usage. The forecasting showed that this technology has entered fast growth stage, a lot of accumulating for mass spectrometry has been achieved, it would be another 20 years before the limit could be reached for mass spectrometry technology. Total patent collaborative ratio was 74.84%: inventors kept a close cooperation in the field of mass spectrometry and inventor’s cooperation is a common form for the research and development of mass spectrometry worldwide. All the organizations from US had higher external collaborative ratios, but Japan pay less attention on the external cooperation. US, Japan, and developed European countries were the focused technological market.

Experimental and theoretical characterization of the natural gas migration and accumulation mechanism in low-permeability (tight) sandstone cores

The natural gas migration and accumulation properties of low-permeability (tight) sandstone are among the most important issues in the study of natural gas resource evaluation and exploitation. Understanding the internal mechanisms of these phenomena is critical to guiding the exploitation of natural gas resources and enhancing gas recovery. In this work, physical simulation experiments on gas migration and accumulation in natural tight sandstone cores are designed and implemented. The results show that the flow curve of steady gas migration is non-linear at a low pressure gradient and then becomes linear with the increase of the squared pressure gradient. The apparent permeability can be used to judge the ease of gas migration in tight sandstone, and the growth of apparent permeability can be divided into three stages (fast growth stage, slow growth stage, and stable stage) according to the level of the pressure gradient. The minimum migration pressure gradient (MMPG) is also determined from the gas displacement experiments. The terminal gas saturation of tight cores is distributed across a wide range of 18.73%–90.03%, and it correlates well with the permeability and MMPG: terminal gas saturation increases as the permeability increases or the MMPG decreases. Gas saturation also increases as the permeability and pressure gradient increase, but the rate of increase varies.

Nitrate reductase activity (NRA) in the invasive alien Fallopia japonica: seasonal variation, differences among habitats types, and comparison with native species

Nitrate reductase activity (NRA) was studied in the invasive alien plant <em>F. japonica</em> (Japanese knotweed) during the vegetation season and among natural, semi-natural, and human-made habitats and compared with NRA in selected native species. NRA was measured directly in the field from the beginning of May until the beginning of October. NRA was much higher than in the plant’s native range, i.e., East Asia, and showed a high degree of variation over time with the highest values being reached at the stage of fast vegetative growth and at the beginning of fruiting. NRA was highest on dumping sites probably due to the high nitrogen input into soils and near traffic and the emission of NO<span><em><sub>x</sub></em></span> by vehicles. A comparison of the enzyme activity in four selected native plant species indicated that NRA in <em>F. japonica</em> was the highest with the exception of <em>Urtica dioica</em>, which exhibited a similar activity of the enzyme. A detailed comparison with this species showed that differences between these species on particular dates were influenced by differences in the phenology of both plants. The initial results that were obtained suggest that nitrogen pollution in an environment can contribute to habitat invasibility and a high level of NRA, which in addition to the many plant traits that are commonly accepted as characteristic of invasiveness features, may be an important factor that enhances invasion success.

Monitoring and modeling of urban sprawl through remote sensing and GIS in Kuala Lumpur, Malaysia

Kuala Lumpur is currently experiencing a large-scale urban transformation. This study explores a multi-buffer ring method to investigate the spatial and temporal dynamics of urban growth in the Kuala Lumpur metropolitan area by using Geographical Information Systems (GIS) and remote sensing imageries from1989 to 2014. The first Landsat images from 1989, 2001, and 2014 were classified with maximum likelihood classification to produce land cover maps and identify four types of land cover: urban/built-up, agriculture, forest, and water. Then, the area coverage for all the land use types at different points in time were measured and combined with distance from the city center. Later on, urbanization densities from the city center to the outside for every 1-km distance from 1 to 50 km are calculated. City density on the distance of 5, 8, 15, 20, and 30 km was very high in the years 1989 and 2014. Temporally, urban expansion shows fast and slow growth stages with high-speed growth shifting to the east side of the city. In general, the population, traffic conditions, industrialization, and policy are the major factors thatinfluenced the urban expansion

Phase state variations for supercritical carbon dioxide drilling

AbstractA phase state prediction model during supercritical carbon dioxide (SC‐CO2) drilling is established, considering the enthalpy changes caused by the flow work variations and changes in kinetic energy, as well as the potential energy caused by the fluid velocity along with physical property variations. The results show that variations in the flow work affect the temperature field of the SC‐CO2 fluid significantly. Phase state transitions of the fluid in the drill pipes and the annulus exist; in this example, the depth of the phase transition point in the drill pipes is in the range of 600 to 1000 m, while in the annulus, it is in the range of 400 to 700 m. Different results are observed when the phase state prediction is conducted by adjusting the discharge capacities, injecting temperature and pressure. When the discharge capacity is increased, the phase transition points in the drill pipes and the annuluses move downward; the pressure of the bit nozzle upstream increases gradually, while the pressure of the bit nozzle downstream changes slightly. When the wellhead back pressure is increased, the depths of the phase transition points in the drill pipes and the annulus decrease. Moreover, the pressure variations of the bit nozzle upstream and downstream can be divided into two stages: the fast growth stage and the slow growth stage. When the injection temperature is increased, the depths of the phase transition points in the drill pipes and the annulus are reduced; the temperature drop and the pressure drop at the nozzle change slightly. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Quantitative analysis of intraspecific variations in the carbon and oxygen isotope compositions of the modern cool-temperate brachiopod Terebratulina crossei

This study unravels intraspecific variations in the carbon isotope (δ13C) and oxygen isotope (δ18O) compositions of shells of the modern cool-temperate brachiopod Terebratulina crossei collected at a water depth of 70m in Otsuchi Bay, northeastern Honshu, Japan. Brachiopod shells have been used as proxies of the δ13C values of dissolved inorganic carbon (DIC) (δ13CDIC) and seawater temperature/δ18O (δ18OSW) values to reconstruct the evolution of Phanerozoic oceans. To identify more reliable shell portions as the proxies, we conducted a rigorous time-series comparison of δ13C and δ18O values between the brachiopod shells and calcite precipitated in isotopic equilibrium with ambient seawater (equilibrium calcite) (δ13CEC and δ18OEC values, respectively). Samples were collected from the outer and inner surfaces of the secondary shell layer along the maximum growth axis (ontogenetic-series and inner-series samples, respectively). The ontogenetic-series δ13C values, which showed regular annual and irregular non-annual cycles, partly fell in but were mostly less than the range of the δ13CEC values. The δ13C cycles were often associated with one or two minor negative peaks. The peaks were likely resulted from an increased incorporation of respiration-derived 12C due to elevated metabolic activity during spawning. The ontogenetic-series δ18O values showed distinct seasonal variations and were mostly within the range of δ18OEC values. The amplitude of the δ18O profiles was relatively large during the younger fast-growth stage, and decreased during the senescent slow-growth stage. The inner-series δ13C and δ18O values of individual shells varied within narrow ranges. The inner-series δ13C values were close to the minimum δ13CEC values. The inner-series δ18O values were in the upper range of the δ18OEC values. Kinetic isotope fractionation effects were evident, but its degree varied among different shells. We identified the shell portions reliably recording past ocean environments. The best estimates of annual average δ13CDIC values were obtained from ontogenetic-series δ13C values near the anterior shell edge and from inner-series δ13C values; those of the annual average seawater temperature were obtained from ontogenetic-series δ18O values from the entire transect and from the fast-growth stage.