内蒙古乌梁素海湖泊沉积物元素地球化学特征及其影响因素

在210Pb同位素测年的基础上,通过对乌梁素海沉积物元素含量的分析,研究了沉积物中元素的变化规律,探讨了沉积物中元素变化的影响因素,结果表明沉积物中Ca、Sr、Cu、Mn、P等元素随深度加深含量下降,其余元素含量随深度加深呈增加的趋势。通过对元素富集系数的变化规律进行研究后,发现Ca、Sr、Cu、Mn、P等元素的富集系数与其含量变化趋势基本相同,反映了该组元素主要受沉积通量的影响;Al、K、Be、Ba、Mg等富集系数与其含量的变化趋势具明显差异,与黏土含量变化一致;而Cr、Fe、Ni、V、Co、Pb、Zn等重金属元素可能受到黏土吸附作用影响。最后,应用有序样品聚类分析方法,对元素这一环境代用指标在研究湖泊历史演化中的作用进行了探讨,研究表明:在湖泊演化过程中,湖泊的形成、20世纪70年代入湖水量的急剧改变以及近年来河套灌区化肥用量逐年加大、大量生活污水和工业废水排入等人类活动的增强等事件,均在湖泊沉积物元素的变化中有所体现。     

防城河口湾鱼类群落结构及其与环境因子关系研究

文章根据2016年5月、8月、11月和2017年2月在防城河口湾海域进行的渔业资源和环境调查数据, 研究了河口湾鱼类群落结构及其空间和季节变化, 分析了鱼类群落结构与主要环境因子的关系。结果表明: 全年调查共渔获鱼类95种, 隶属于2纲12目37科69属, 适温性以暖水性鱼类为主, 生态类型以底层和近底层鱼类为主。其中, 春季60种, 夏季59种, 秋季54种, 冬季46种, 夏—秋季间种类相似性指数最高。全年优势种为褐菖鲉Sebastiscus marmoratus和长鳍篮子鱼Siganus canaliculatus, 主要种有黄鳍棘鲷Acanthopagrus latus、条马鲾Equulites rivulatus、李氏?Callionymus richardsoni和真赤鲷Pagrus major等10种; 夏、秋季的最大优势种均为长鳍篮子鱼, 春、冬季的最大优势种分别为褐菖鲉和条马鲾。全湾鱼类年均资源密度为45836尾·km ^-2和 435.21kg·km ^-2, 资源密度具有明显的空间差异和季节变化。全年各站位种数变化范围在2~21种, 多样性指数H′在0.468~4.031, 丰富度指数d在0.120~1.926, 均匀度指数J在0.181~0.969。聚类分析、单因子相似性分析(ANOSIM)及相似性百分比(SIMPER) 分析表明该海域鱼类群落存在一定程度的时空异质性。相关性分析表明影响防城河口湾鱼类群落结构的主要环境因子为水温、盐度和硝酸盐。     

浙江省三疣梭子蟹产量波动及潜在影响因素分析

依据2000—2015年浙江省三疣梭子蟹(Portunustrituberculatus)渔获量的数据,以及影响渔获量的因素(管理类因素、环境类因素和营养关系类因素等共11个因子),使用广义加性模型(GAM)对各类因素对三疣梭子蟹渔获量的影响进行了分析。结果显示,赤潮面积、捕捞努力量和放流数量对三疣梭子蟹渔获量影响显著(P0.01)。3个因子的累积解释比率达98.3%,其中,赤潮的解释比率最大,达到47.2%,捕捞努力量的解释比率为37.8%,放流数量的解释比率为13.3%。三疣梭子蟹渔获量随着赤潮面积增加有所减少,随着捕捞努力量的加大有迅速增加的趋势,与放流尾数呈现正相关趋势。三疣梭子蟹渔获量的波动受诸多因素的影响。今后需开展更深入的研究,找到可能影响三疣梭子蟹渔获量的其他关键因素。     

Axial friction response of full-scale pipes in soft clays

The axial friction response of subsea pipelines in soft clays is a very important aspect for designers of subsea pipelines but the response is not well understood so far. There is a pressing need for the comprehension of the response. In this paper, model tests are performed using full-scale pipes coated with polyethylene (PE) to study the effects of the set-up period, the pipe diameter, the buried depth of the pipe, the shear strength of soft clays and the loading rate on the axial friction response of pipelines in soft clays. The variations of the axial friction coefficient are analyzed using the effective stress method based on model test results. The results show that the axial friction resistance increases with the increasing pipe diameter but the effect of the pipe diameter on the axial friction coefficient can be neglected. The ultimate axial resistance also increases with the increase of the buried depth of pipelines, the undrained shear strength of soft clays and the loading rate. The axial friction coefficient increases with the increasing loading rate. However, the axial friction coefficient decreases with the increasing buried depth. The method to determine the axial friction coefficient is developed by analyzing model test results, which considers the effects of the diameter, the buried depth, the undrained shear strength of soft clays and the loading rate. The study results not only extend the industry data base but also supply a basis to determine the axial friction coefficient of PE-coated pipes in soft clays for ocean engineering geological investigations.     

基于综合环境因子的协同克里金法分析茎柔鱼资源丰度空间分布

茎柔鱼是我国重要的远洋捕捞对象之一,研究其资源丰度空间分布问题,有助于更好地理解茎柔鱼的生态习性,并提高我国鱿钓渔船的生产效率。本文利用上海海洋大学鱿钓技术组提供的2003-2012年6-9月秘鲁外海茎柔鱼捕捞数据,结合海表面温度（SST）,海表面高度（SSH）,海表面盐度（SSS）和叶绿素浓度（Chl a）进行协同克里金插值预测其资源丰度的空间分布。为了解决协同克里金插值中4个环境因子的权重问题,本文将4个环境因子进行归一化处理,利用主成分分析方法将其整合为单一综合环境因子,以此作为协变量。将综合环境因子与单位捕捞努力量渔获量（CPUE）进行相关性检验后进行协同克里金插值,根据平均误差（ME）,均方根误差（RMSE）和标准化均方根（RMSSE）对插值结果评价,探讨此种方法的可行性。研究结果认为:（1）主成分分析方法获得的6-9月份的综合环境因子均与CPUE具有显著相关性;（2）6-7月份ME分别为0.002 6和0.002 5,预测准确性很高,平均预测结果稍高于实际观测值;而8-9月份的ME分别为-0.007 8和-0.000 2,预测准确性较高,平均预测结果稍低于实际观测值。6月份的RMSE估值精度最高,8月份的估值精度最低。6-7月份的RMSSE值小于1,说明都高估了预测的不确定性,8-9月份的RMSSE值大于1,说明都低估了预测的不确定性,则在6-9月份中的预测精度和准确性上会有一定程度的偏差。从ME、RMSE和RMSSE三者综合来看,6-9月的预测值具有一定的可靠性。     

Analytical convolution model for shipping water evolution on a fixed structure

The shipping of water is a problem that affects naval and offshore structures. Estimating its propagation on the decks of these structures by using analytical methods has been a main concern of projects. However, classical approaches disregard the decay tendency of water elevation time series and tend to overestimate the resultant water on deck. This paper is concerned with estimating the evolution of water along the deck of a fixed structure due to shipping water events. An analytical convolution model is proposed to estimate water elevations. The model considers the freeboard exceedance time series and the mean shipping flow velocity as inputs and the frictional effects of the bottom by resistance coefficients, which enables an approximated representation of the water elevation time series over the deck. It was validated with experiments of isolated shipping water events that were generated with the wet dam-break approach. The results obtained with the proposed model captured the experimental results, approximating the peak values and the decay trend of time series. Improvement of the proposed approach over classical models to represent shipping water elevations was demonstrated by comparing the results obtained with those of the dam-break model of Stoker.     

Primary molecular basis of androgenic gland endocrine sex regulation revealed by transcriptome analysis in Eriocheir sinensis

In crustaceans, the male sexual dif ferentiation and maintenance are specially regulated by androgenic gland(AG). However, little is known about the genes involved in the regulation process.RNA-Seq was performed on AG with ejaculatory duct(AG_ED) and ejaculatory duct(ED) as control in Eriocheir sinensis, one of the most important economic and ?shery crabs with typically sex dimorphism. A total of 925 unigenes were identi?ed as dif ferentially expressed genes(DEGs) and the expression of nine genes randomly selected was con?rmed by qRT-PCR. 667 unigenes were up-regulated in AG_ED, being supposed to be AG preferential genes. Among them, the full length of i nsulin-like androgenic gland factor( IAG) cDNA named as Es-IAG was obtained as a logo gene of AG, which together with the genes i nsulin-like receptor( INR), and s ingle insulin binding domain protein( SIBD), might constitute the sex regulation pathway. Several sex related genes were identi?ed, and their function will have to be investigated. Also,the identi?cation of j uvenile hormone epoxide hydrolase 1( JHEH1), ecdysteroid 22-hydroxylase( DIB) and e cdysone receptor( ECR) preliminarily clari?ed the molecular regulation mechanism of eyestalk-AG-testis axis, which plays important roles in molting and reproduction. The results will enhance our understanding for the molecular basis of the AG involved in male sex regulation in crabs.     

Decomposing productivity and efficiency changes in the Alaska head and gut factory trawl fleet

Fishing fleets are subject to numerous factors that affect economic performance, making identification and attribution of such impacts difficult. This paper separately identifies the effects of changing input and output prices, fishery management, and quota allocations on total factor productivity using a Lowe Index. Indices account for technical change and decompose productivity estimates into its technical, environmental, and scale-mix components. This results in measures that reflect shifts in the production frontier, and movements by vessels toward and around the frontier, to capture economies of scale and mix after a policy shift to a catch share program that includes fishing cooperatives and a limited access fishery. The difference between cooperative and limited access vessels is exploited to compare the changes in economic performance between the groups after the introduction of the shift to catch shares and cooperative management, which allowed the vessels to improve the timing and coordination across multi-species fisheries and to decrease incidental catch of quota-limited bycatch species that had closed the target fisheries prematurely in the past. Results indicate that total factor productivity increased significantly after the move to a catch share program, largely due to increases in technical change that shifted out the production frontier of the fishery.     

Performance investigation of a two-raft-type wave energy converter with hydraulic power take-off unit

Raft-type wave energy converter (WEC) is a multi-mode wave energy conversion device, using the relative pitch motion to drive its hydraulic power take-off (PTO) units for capturing energy from the ocean waves. The hydraulic PTO unit as its energy conversion module plays a significant role in storing large qualities of energy and making the output power smooth. However, most of the previous investigations on the raft-type WECs treat the hydraulic PTO unit as a linear PTO unit and do not consider the dynamics of the hydraulic circuit and components in their investigations. This paper is related to a two-raft-type WEC consisting of two hinged rafts and a hydraulic PTO unit. The aim of this paper is to make an understanding of the dynamics of the hydraulic PTO unit and how these affect the performance of the two-raft-type WEC. Therefore, a combined hydrodynamic and hydraulic PTO unit model is proposed to investigate and optimize the performance of the two-raft-type WEC; and based on the simulation of the combined model, the relationships between the optimal power capture ability, the optimal magnitude of the hydraulic PTO force and the wave states are numerically revealed. Results show that an approximately square wave type hydraulic PTO force is produced by the hydraulic PTO unit, which causes the performance of the two-raft-type WEC not to be sinusoidal and the energy capturing manner different from that of the device using a linear PTO unit; moreover, there is an optimal magnitude of the hydraulic PTO force for obtaining an optimal power capture ability, which can be achieved by adjusting the parameters of the hydraulic PTO unit; in regular waves, the optimal power capture ability as well as the optimal magnitude of the hydraulic PTO force normalized by the wave height presents little relationship with the wave height, mainly depends on the wave period; in irregular waves, the trends of the optimal power capture ability and the normalized optimal magnitude of the hydraulic PTO force against the peak wave periods at different significant wave heights are generally identical and show a good correlation. All means that the hydraulic PTO unit of the two-raft-type WEC can be tuned to the wave states, and these would provide a valuable guidance for the optimal design of its hydraulic PTO unit.     

Geochemical types of pacific polymetallic nodules: An application of multivariate analysis

A total of 843 samples of Pacific Ocean polymetallic nodules (PNs) from five survey areas have been studied (metals analyzed: Mn, Fe, Ni, Cu, Co, Zn, Pb). The statistical analysis included the following techniques: factor R analysis, quick cluster Q analysis into 50 preclasses, various hierarchical cluster Q analyses (HCAs) using the preclasses (application of different HCAs to an identical set of data and of an identical HCA to two different subsets of the data), comparison of the HCA. The PNs of the survey areas can be grouped into five geochemical types (I‐V). The genesis of the PNs was interpreted as early diagenetic, hydrogenetic, and mixed (early diagenetic/hydrogenetic and hydrogenetic/hydrothermal. In addition, some further conclusions regarding the applicability of various HCA techniques depending on the structure of the data set have been drawn.