Challenges in developing China's marine protected area system

Since the 1980s, there have been continuous increases in the coverage of marine protected areas (MPAs) in China, and a total of 158 MPAs have been declared. The MPA system in China is characterized by (1) decentralised designation and management with reduced control from the central government; (2) a dominance of de jure fully protected MPAs that are often implemented as de facto multiple-use areas; and (3) a lack of objective evaluation processes. To improve China's MPA system requires an appropriate integration of fully protected and multiple-use MPAs, and an approach that balances the advantages of top-down and bottom-up approaches.     

Development of MSP430-based ultra-low power expandable underwater acoustic recorder

Reducing overall power consumption is core issue in low power, high sampling rate, large storage data loggers necessary for long-term underwater acoustics research and other applications. A low-power microprocessor MSP430 offers a solution for the development of long-term deployment remote systems. In this paper, we present a multi-MSP430, master-slave architecture to resolve the power limitation issue. The proposed design is scalable in nature. For every additional slave unit installed in the array, the data sampling and streaming rate can be increased proportionally. We demonstrate the advantages of this concept using a multi-channel underwater acoustic recorder with a 100 kHz sampling rate. The performance of the system is demonstrated by a field acoustic experiment in which the reflection coefficient of the seafloor is measured. The proposed architecture will be applicable to many underwater long-term deployment systems. With its flexibility in configuration and synchronization of multi-channel sampling, it also provides a simple architecture for the construction of hydrophone arrays.     

Seasonal changes in nitrogen and phosphorus transport in the lower Changjiang River before the construction of the Three Gorges Dam

Water and sediment samples were collected at Datong from June 1998 to March 1999 to examine seasonal changes in the transports of nitrogen (N) and phosphorus (P) from the Changjiang River (Yangtze River) to the East China Sea (ECS). Dissolved inorganic nitrogen (DIN; dominated by nitrate) concentration exhibited small seasonality, and DIN flux was largely controlled by water discharge. Dissolved inorganic phosphorus (DIP) concentration was inversely correlated with water discharge, and DIP was evenly delivered throughout a year. The transports of DIN and DIP from the Changjiang River were consistent with seasonal changes in nutrient distributions and P limitation in the Changjiang Estuary and the adjacent ECS. Dissolved organic and particulate N (DON and PN) and P (DOP and PP) varied parallel to water discharge, and were dominantly transported during a summer flood. The fluxes of DOP and particulate bioavailable P (PBAP) were 2.5 and 4 times that of DIP during this period, respectively. PBAP accounted for 12–16% of total particulate P (PP), and was positively correlated with the summation of adsorbed P, Al–P and Fe–P. Ca–P, the major fraction of PP, increased with increasing percent of CaCO₃. The remobilization of riverine DOP and PBAP likely accounted for the summer elevated primary production in DIP-depleted waters in the Changjiang Estuary and the adjacent ECS. The Changjiang River delivered approximately 6% of DIN (1459 × 10⁶ kg), 1% of DIP (12 × 10⁶ kg), and 2% of dissolved organic and particulate N and P to the totals of global rivers. The construction of the Three Gorges Dam might have substantially reduced the particulate nutrient loads, thereby augmenting P limitation in the Changjiang Estuary and ECS.     

Numerical study on salinity stratification in the Pamlico River Estuary

The variations of current circulation, salt intrusion, and vertical stratification under different river flow and wind conditions in the Pamlico River Estuary (PRE) were investigated in this paper using a three-dimensional numerical model. The model was calibrated and verified against water level variation, temperature, and salinity variations during 2003 and 2001, respectively. Eight sensitivity tests were conducted with different river flow and wind conditions specified in the model. Model results show that salinity intruded further upstream under scenarios with low flow, downriver local wind, and remote-wind-caused water level set-up conditions. In contrast, the responses of salinity stratification to different environmental forcing functions were different in different portions of the estuary. Salinity stratification was enhanced under high flow condition at the lower part of the estuary, under upriver wind near the river mouth, under downriver wind at the upstream to middle portion of the estuary, and under remote-wind-caused water level set-up condition at the majority of the estuary except near the river mouth. Model results also show that across-channel wind tended to reduce salt intrusion and salinity stratification in the PRE through increased vertical mixing.     

西湖凹陷油气成藏的主控因素

西湖凹陷位于东海大陆架边缘,地壳为相对软弱的过渡壳。西湖凹陷中新世末以前属于萎缩型盆地,上新世伴随冲绳海槽的形成才成为扩张性盆地。受构造控制盆地萎缩期沉积有以下3个特点：第一,整体表现为海退;第二,沉积范围逐次减小;第三,泥岩百分比越来越低,盖层条件越来越差。平湖组存在区域盖层,钻遇断块气藏;花港组存在局部盖层,背斜充满度高,断背斜充满度低,断块未成藏;新近系盖层条件更差,断背斜亦未能成藏。由此可见保存条件是西湖凹陷油气成藏的主控因素,保存条件好的领域是西湖凹陷下一步勘探的方向。     

西湖凹陷中南部油气成藏动力学特征及成藏机理

西湖凹陷以始新世末的玉泉运动和中新世末的龙井运动形成的不整合面为界,将盆地的发展演化分为裂陷、坳陷和区域沉降三个阶段。在盆地演化的不同阶段,不同构造带的沉降速率存在差异,烃源岩的热成熟演化史也不一致。生、排烃史模拟表明：平湖组烃源岩的生烃强度最高,花港组烃源岩的生烃强度相对较小;中央背斜带及其两侧深凹部位烃源岩的生烃强度大于保斜坡带;主要应用Basin Mod盆地模拟软件系统,通过对流体势、温压系统、异常压力的分析,探讨西湖凹陷中南部油气运聚成藏的机理。     

Paleoenvironmental implications of the guano phosphatic cementation on Dongdao Island in the South China Sea

The phosphatic cement in the bioclastic sediment sequence on the northeastern shore of Dongdao Island in the South China Sea was studied and its paleoenvironmental implications discussed. Petrological characteristics and major, trace, REE element data unequivocally supported the notion that phosphatization was closely associated with avian guano decomposition and leaching, whereas carbon and oxygen isotope results further revealed that meteoric water were involved in these processes. AMS ¹⁴C dates on the brown phosphate cements indicate that they were formed around 5700, 5000–5100 and 2900 yr BP, respectively. The multi-episodes of phosphatization very likely correspond to intermittent seabird occupation on this island — possibly reflecting Holocene sea-level oscillation and/or long term climate changes in the South China Sea that have controlled seabird habitat. The phosphate cementation, which occurs widely in tropical islands, may be another useful monitor for sea-level and/or paleoclimate changes.     

Analysis of second-order resonance in wave interactions with floating bodies through a finite-element method

A time-domain method is employed to analyse the resonant oscillations of the liquid confined within the two floating bodies. The velocity potentials at each time step are obtained through a finite-element method (FEM) with quadratic shape functions. The matrix equation of the FEM is solved through an iteration. The radiation condition is satisfied through a combination of the damping zone method and the Sommerfeld–Orlanski equation. A detailed analysis is made for two rectangular floating cylinders undergoing forced oscillation. The first-order potential reveals the resonant behaviour of the wave motion at certain frequencies ω_i, which is similar to sloshing in a tank. More interestingly, the second-order theory further reveals that when the oscillation frequency is at ω_i/2 or half of the resonant frequency, no first-order resonance is observed as expected, but the second-order resonant motion becomes evident, which does not seem to have been extensively investigated so far. Detailed results for two rectangular cylinders are provided to show some insights into the resonant effect due to the interaction between the bodies. The first- and second-order resonant phenomena have been observed and the result has shown that the second-order components have significant influence on the wave and force in some cases, especially at the second-order resonance.     

Spatial pattern formation of a ratio-dependent predator—prey model

This paper presents a theoretical analysis of evolutionary process that involves organisms distribution and their interaction of spatially distributed population with diffusion in a Holling-III ratio-dependent predator--prey model, the sufficient conditions for diffusion-driven instability with Neumann boundary conditions are obtained. Furthermore, it presents novel numerical evidence of time evolution of patterns controlled by diffusion in the model, and finds that the model dynamics exhibits complex pattern replication, and the pattern formation depends on the choice of the initial conditions. The ideas in this paper may provide a better understanding of the pattern formation in ecosystems.     

A universal algorithm to generate pseudo-random numbers based on uniform mapping as homeomorphism

A specific uniform map is constructed as a homeomorphism mapping chaotic time series into [0,1] to obtain sequences of standard uniform distribution. With the uniform map, a chaotic orbit and a sequence orbit obtained are topologically equivalent to each other so the map can preserve the most dynamic properties of chaotic systems such as permutation entropy. Based on the uniform map, a universal algorithm to generate pseudo random numbers is proposed and the pseudo random series is tested to follow the standard 0-1 random distribution both theoretically and experimentally. The algorithm is not complex, which does not impose high requirement on computer hard ware and thus computation speed is fast. The method not only extends the parameter spaces but also avoids the drawback of small function space caused by constraints on chaotic maps used to generate pseudo random numbers. The algorithm can be applied to any chaotic system and can produce pseudo random sequence of high quality, thus can be a good universal pseudo random number generator.