Pore characterization of organic-rich Lower Cambrian shales in Qiannan Depression of Guizhou Province,Southwestern China

Nine organic-rich shale samples of Lower Cambrian black shales were collected from a recently drilled well in the Qiannan Depression, Guizhou Province where they are widely distributed with shallower burial depth than in Sichuan Basin, and their geochemistry and pore characterization were investigated. The results show that the Lower Cambrian shales in Qiannan Depression are organic rich with TOC content ranging from 2.81% to 12.9%, thermally overmature with equivalent vitrinite reflectance values in the range of 2.92–3.25%, and clay contents are high and range from 32.4% to 53.2%. The samples have a total helium porosity ranging from 2.46% to 4.13% and total surface area in the range of 9.08–37.19 m²/g. The estimated porosity in organic matters (defined as the ratio of organic pores to the volume of total organic matters) based on the plot of TOC vs helium porosity is about 10% for the Lower Cambrian shales in Qiannan Depression and is far lower than that of the Lower Silurian shales (36%) in and around Sichan Basin. This indicates that either the organic pores in the Lower Cambrian shale samples have been more severely compacted than or they did not develop organic pores as abundantly as the Lower Silurian shales. Our studies also reveal that the micropore volumes determined by Dubinin–Radushkevich (DR) equation is usually overestimated and this overestimation is closely related to the non-micropore surface area of shales (i.e. the surface area of meso- and macro-pores). However, the modified BET equation can remove this overestimation and be conveniently used to evaluate the micropore volumes/surface area and the non-micropore surface areas of micropore-rich shales.     

The precautionary principle and its approach to risk analysis and quarantine related to the trade of marine ornamental fishes in Brazil

The objective of this study was to employ the precautionary principle in import risk analysis (IRA) and quarantine in the trade of marine ornamental fishes (MOF). The analysis focused on the example of Brazil, as it imports and exports these fishes, in amounts that are globally significant. These processes, since their collection in nature, may expose the fish to stress, which may lead to the development of diseases. The legislation that regulates IRA and quarantine is derived from the Ministries of Agriculture, Livestock and Supply and Fisheries and Aquaculture. The quarantine of MOF in Brazil is not undertaken by government agencies, but by commercial establishments that are registered with the Ministries, and is way too short. According to the data obtained, the precautionary approach is not applied at all in this trade, as scientific information is not contemplated by the legislation, and law is not enforced.     

Wave-porous structure interaction modelling using Improved Meshless Local Petrov Galerkin method

This paper presents the application of the Improved Meshless Local Petrov Galerkin method with Rankine source (Sriram and Ma, 2012) Sriram and Ma (2012) for wave interaction with porous structure model. The mathematical model is based on a unified governing equation that incorporates both pure fluid and porous region. The porous flow model is based on the empirical resistance coefficients. The interface between the pure fluid and porous region is numerically treated using background nodes having the porosity information and interpolated over the particle using simplified finite difference interpolation method. The model is validated using the available experimental results for wave damping over the permeable bed. The developed model is used to analyse the different shape of the seawall such as flaring shaped seawall, recurve wall and vertical wall. Then the validated model is used for analysing the overtopping amount due to the effect of porous layer in-front of the different sea wall profile. Numerical expression for overtopping amount has been provided for the different configurations from the numerical model.     

南海冬季之西边界流：1998年2月的水文结构与体积输运

The unique survey in December 1998 mapped the entire western boundary area of the South China Sea(SCS),which reveals the three-dimensional structure and huge volume transport of the swift and narrow winter western boundary current of the SCS(SCSwwbc) in full scale. The current is found to flow all the way from the shelf edge off Hong Kong to the Sunda Shelf with a width around 100 km and a vertical scale of about 400 m. It appears to be the strongest off the Indo-China Peninsula, where its volume transport reached over 20×10~6 m~3/s. The current is weaker upstream in the northern SCS to the west of Hong Kong. A Kuroshio loop or detached eddy intruded through the Luzon Strait is observed farther east where the SCSwwbc no more exists. The results suggest that during the survey the SCSwwbc was fed primarily by the interior recirculation of the SCS rather than by the"branching" of the Kuroshio from the Luzon Strait as indicated by surface drifters, which is likely a near-surface phenomenon and only contributes a minor part to the total transport of the SCSwwbc. Several topics related to the SCSwwbc are also discussed.     

Population connectivity of an overexploited coastal fish,Argyrosomus coronus (Sciaenidae), in an ocean-warming hotspot

The West Coast dusky kob Argyrosomus coronus is a commercially exploited fish with a distribution confined to the Angola–Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean. A previous study revealed that during a recent period of local warming the species extended its distribution into Namibian waters, where it hybridised with the resident and congeneric Argyrosomus inodorus. Environmental changes are a major threat to marine biodiversity and when combined with overfishing have the potential to accelerate the decline of species. However, little is known regarding the evolutionary history and population structure of A. coronus across the ABFZ. We investigated genetic diversity, population structure and historical demographic changes using mtDNA control region sequences and genotypes at six nuclear microsatellite loci, from 180 individuals. A single, genetically homogeneous population was indicated across the distributional range of A. coronus (φ_ST = 0.041, F_ST = 0.000, D = 0.000; p > 0.05). These findings imply that the oceanographic features within the ABFZ do not appear to significantly influence population connectivity in A. coronus, which simplifies management of the species. However, reconstruction of the demographic history points to a close link between the evolutionary history of A. coronus and the environmental characteristics of the ABFZ. This outcome suggests the species’ vulnerability to the rapid environmental changes being observed across this region, and highlights a pressing need for transboundary management to mitigate the impacts of climate change in this global hotspot of seawater temperature changes.     

Inter-basin movements of Mediterranean sperm whales provide insight into their population structure and conservation

The sperm whale is one of the very few deep diving mammal species in the Mediterranean Sea. Following a rare mass stranding of male sperm whales in the Adriatic Sea in December 2009, photo-identification methods were used in order to investigate previous sightings of the stranded whales in the region. Fluke photos of the stranded whales were compared with those of 153 and 128 free-ranging individuals photographed in the western and eastern Mediterranean basins, respectively. Three out of the seven stranded whales had been previously photo-identified and some of them more than once. To reach the stranding place, two of these re-identified whales performed long-range inter-basin movements of about 1600-2100 km (in a straight line) either through the Strait of Sicily or the Strait of Messina. In addition, comparisons among all whales photographed in the two Mediterranean basins revealed that one more individual first photographed in the western basin (1991) was re-identified 13 years later in the eastern basin (2004). These three cases provide the first conclusive evidence of inter-basin movement of sperm whales in the Mediterranean Sea. Inter-basin gene flow is important for the survival of the small and endangered Mediterranean sperm whale population. Mitigating the disturbance created by human activities in the straits area is crucial for its conservation.     

Water wave interaction with a floating porous cylinder

The interaction of water waves with a freely floating circular cylinder possessing a side-wall that is porous over a portion of its draft is investigated theoretically. The porous side-wall region is bounded top and bottom by impermeable end caps thereby resulting in an enclosed fluid region within the structure. The problem is formulated based on potential flow and linear wave theory and assuming small-amplitude structural oscillations. An eigenfunction expansion approach is then used to obtain semi-analytical expressions for the hydrodynamic excitation and reaction loads on the structure. Numerical results are presented which illustrate the effects of the various wave and structural parameters on these quantities. It is found that the permeability, size and location of the porous region may have a significant influence on the horizontal components of the hydrodynamic excitation and reaction loads, while its influence on the vertical components in most cases is relatively minor.     

闽中、闽东渔场扁舵鲣的资源生物学

本文以1981～1984年4～9月累计18个月在闵中、闵东渔场开展中上层鱼类资源开发性探捕调查的材料,报道了扁舵鲣的生态分布、群体结构和生活史主要特征。鱼群先后于4～7月由南而北进入本渔场,数量分布以5月为多;栖息的最适温、盐度分别为23.5～25.5℃和33～34;渔获群体由0～V龄组成;性成熟的最小年龄为Ⅰ龄,最小叉长271～280mm;生长参数L_∞=484.44mm,W_∞=2050.76g,K=0.5109,t_0=0.3598;瞬时自然死亡率为0.8937,开发比率为0.2138,属于轻度利用的鱼类资源,尚有较大的开发潜力。     

南海西北部夏冬季浮游介形类的分布及其影响因素

海洋浮游介形类(Ostracods)是一类分布较广的小型甲壳动物, 在海洋碳循环中起重要作用。目前国内海洋浮游动物采样常使用505μm网目孔径的浮游生物网, 从而导致个体较小的介形类被忽略。文章根据2006年7—8月(夏季)和2006年12月—2007年1月(冬季)在南海西北部海域分别使用网目孔径为505μm和160μm浮游生物网采集的样品, 比较不同网目所获浮游介形类种类和丰度的差异, 分析介形类种类和丰度的分布特征, 探讨环境因素对其时空分布的影响。160μm网目采集的浮游介形类种类和丰度均高于505μm。基于160μm网目数据分析浮游介形类群落结构: 1) 鉴定浮游介形类32种, 其种数由近岸向外海递增, 等深线100m以浅海域的种数显著高于100m以深海域(p<0.01); 2) 夏季浮游介形类的丰度高于冬季, 夏季丰度高值区主要出现在雷州半岛东部和琼东近岸, 显著高于外海(p<0.05), 冬季介形类丰度分布较为均匀; 3) 优势种针刺真浮萤(Euconchoecia aculeata)是近岸高丰度的主要贡献种; 4) 介形类种数与温度和水深呈显著正相关, 丰度与叶绿素a浓度呈正相关, 而与温度和盐度呈负相关。夏季琼东沿岸上升流和粤西沿岸流有助于浮游介形类在雷州半岛和海南岛东部近岸海域形成较高的丰度, 最高达1252个·m^-3。同时, 建议今后研究浮游介形类采用网目孔径小的浮游生物网进行采集以便全面评估其群落结构特征。