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1.
Anthropogenic emission of atmospheric carbon dioxide(CO_2) has led to a rapid increase in atmospheric CO_2 concentration. Increasing atmospheric CO_2 can reduce seawater pH and carbonate ions, which may adversely affect the survival of the larvae of calcareous animals. Cyclina sinensis is a commercially and ecologically important species in several Asian countries. Living in coast shallow waters, this species has experienced the coastal environmental changes frequently throughout its life cycle. In this study, we simulated possible future seawater pH values including 8.2, 7.8 and 7.4 and examined the effects of ocean acidification on the early development of C. sinensis. Clam embryos were incubated for 48 h(2 d) in control and high-CO_2 seawater to compare embryogenesis, larval growth and swimming behavior. Fertilization rate was quite sensitive to pH, and moderate acidification could induce a significant decrease in fertilization rate. However, only extreme acidification could bring significant negative effect to hatching rate, body size, and average path velocity of trochophora. Moreover, with seawater acidification, C. sinensis needs much more time to reach the same developmental stage, which increases the risk of larva survival. Together with recent studies demonstrating negative impacts of high CO_2 on fertilization and larva swimming behavior, the results imply a future decrease of C. sinensis populations in oceans if its acclimation to the predicted environmental alteration does not occur.  相似文献   
2.
新疆西昆仑奥尔托喀讷什锰矿地质、地球化学及成因   总被引:2,自引:1,他引:1  
近年来,西昆仑玛尔坎苏地区富锰矿找矿取得重大突破,新发现奥尔托喀纳什等大型锰矿床。该矿床层位稳定,厚度较大,Mn平均品位达35%以上,为中国最富的碳酸锰矿床,属于典型的海相沉积型锰矿床。锰矿体主要赋存于晚石炭世喀拉阿特河组地层中,该组岩性为一套浅海碳酸盐岩台地相沉积建造组合,可划分为台内浅滩、潮坪、开阔台地、局限台地等4个相类型。成矿分为三个期次,第一期为沉积成岩成矿期,矿石矿物由菱锰矿、锰方解石、硼锰矿组成;第二期为热液改造期,形成锰镁绿泥石、红锰矿、硫锰矿、锰方解石(脉)、重结晶菱锰矿、蔷薇辉石及滑石、石膏等;第三期为表生氧化期,发育少量软锰矿、水锰矿、硬锰矿等。锰矿石具有较低的Fe/Mn比值、V/(V+Ni)比值和强烈的Ce正异常,表明Mn是在氧化环境下,以氧化物或氢氧化物的形式沉积富集。含锰岩系顶、底板岩石中含较多成熟度较差的中酸性火山岩岩屑,以及具有较低Al/(Al+Fe+Mn)、Y/Ho、Co/Ni比值的锰矿石,说明其成矿物质来源于海底热水活动。奥尔托喀纳什锰矿具有"内源外生"的特点,锰矿石及菱锰矿具有负的δ~(13)C值(-23.3‰~-13.2‰),表明锰矿经历了先成锰氧化物或氢氧化物、再被还原转化成菱锰矿的过程。此外,有机质所导致的更为强烈的还原作用是本矿床富锰矿形成的重要机制。后期构造叠加致使矿体发生变形,矿体形态受褶皱控制。矿石受到强烈改造,形成锰镁绿泥石、红锰矿、蔷薇辉石等,晚期经历氧化淋滤作用形成软锰矿、水锰矿等。  相似文献   
3.
从天津大地构造特征和地层分布入手,综合分析了岩溶热储特征.认为天津地区主要大地构造格局从西北向东南依次为冀中拗陷、沧县隆起和黄骅拗陷,主要断裂有北东向的沧东断裂、天津断裂以及北西向的宁河-宝坻断裂.岩溶地热田主要分布在沧县隆起上,发育了王草庄、大城、潘庄、双窑和小韩庄凸起等地热田.研究认为蓟县系雾迷山组在天津全境普遍分布,岩性为深灰色粗晶白云岩、隧石条带状白云岩,裂缝岩溶发育,孔渗性较好,是主要热储层.寒武系、奥陶系热储在沧县隆起核部大面积缺失,在其他地区广泛分布,是主要热储层之一.沧县隆起的热流值较周围地区高,地热水的来源主要为北部蓟县山区,热水运移的最重要通道是大断裂以及不整合面.  相似文献   
4.
牟平-乳山成矿带是山东省重要的金成矿带,姜格庄金矿位于牟平-乳山成矿带东北部,米山断裂西侧。姜格庄金矿矿床成因为中低温岩浆热液金矿床,控矿构造以近SN向断裂构造为主。矿区内地表出露矿化蚀变带5个,圈定矿体5个,矿体多呈脉状、透镜状,成矿严格受矿断裂控制,产状与蚀变带一致,围岩为邱家单元片麻状黑云二长花岗岩,蚀变主要为硅化、钾化、褐铁矿化等。矿石矿物主要有黄铁矿、褐铁矿及黄铜矿,金矿物主要为自然金等。通过对矿体地质特征和分布规律研究,认为该区域断裂构造内具有较好的找矿潜力。  相似文献   
5.
综述了我国海域无脊椎动物的分类学和系统演化研究的历史和概况,以及我国分类系统学工作者在海洋无脊椎动物分类学、区系与动物地理学、系统发育与分子系统学领域的主要工作,重点介绍了中国科学院海洋研究所的海洋无脊椎动物分类学工作。涉及类群包括原生动物、海绵动物、刺胞动物、线虫、多毛类环节动物、星虫、螠虫、软体动物、节肢动物、苔藓动物、毛颚动物、棘皮动物、半索动物等主要的无脊椎动物门类。涉及海域以我国管辖海域,特别是中国近海为主,也涉及了西太平洋、西南印度洋等深海环境的无脊椎动物类群的分类学报道。本文总结过去,展望未来,对于在我国在海洋无脊椎动物分类与系统演化研究领域成就基础上,发现薄弱环节,研讨今后本学科的发展方向,填补研究空白,赶超本领域国际前沿,都有重要借鉴意义。  相似文献   
6.
赤道东印度洋海域是西半球暖池的重要组成部分,对我国季风系统乃至全球气候变化研究意义重大.印度洋作为海上丝绸之路的交通要道,开展东印度洋海洋调查也是保障海上丝绸之路安全的重要一环.自2010年起,国家自然科学基金委为贯彻落实《国家自然科学基金"十一五"发展规划》的战略部署而设立的"国家自然科学基金委印度洋综合航次",极大地促进了海洋学科多学科交叉和融合,丰富了该海域的海洋观测数据,取得了丰硕的科研成果.本文介绍了2010年起至今的东印度洋海洋学综合科学航次考察的内容、进展和成果,并展望了东印度洋海洋学综合科学考察航次今后的主要方向.  相似文献   
7.
Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species.The growth of heterotrophic microorganisms can be stimulated through adding extra carbon,which reduces the nitrogen level in the water and provides microbial protein to the animals.However,most of the studies and practical applications have been conducted in freshwater and marine environment.This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms.The effect of carbon supplementation on Artemia growth,water quality,and microbial diversity of bioflocs was studied in the closed culture condition without any water exchange.The salinity of the culture medium was 100.A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen(C/N)ratio of 5,15,and 30(Su5,Sul5,and Su30),respectively.The culture without adding sucrose was used as a control.Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level.The results showed that sucrose supplementation at higher C/N ratio(15 and 30)significantly improved the Artemia survival,growth and water quality(P0.05).Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume(BFV)(P0.05).The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness,and shaped the microbial composition at genera level.This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.  相似文献   
8.
Mariculture has rapidly grown worldwide, which might greatly influence the biogeochemical cycle of organic carbon in coastal seas. In this study, several geochemical parameters, including grain size composition, sedimentary total organic carbon(TOC), total nitrogen(TN), stable carbon(δ13 C) and nitrogen(δ15 N) isotopic compositions, were analyzed for surface sediments collected from different mariculture zones of Sanggou Bay and in different seasons. We investigated the composition and distribution of organic matter in surface sediments and further evaluated the contribution of mariculture activities to TOC sources. The TOC and TN contents(mass percentage) in the bay were in the range of 0.14% to 1.45% and 0.03% to 0.20%, respectively. The spatial distribution indicated that sedimentary TOC and TN contents in shellfish monoculture and shellfish-kelp polyculture zones were higher than in other mariculture zones, which might be related to grain size composition and mariculture organisms. Seasonal variations of TOC contents were observed in different mariculture zones. The TOC/TN atomic ratio(C/N), δ13 C and δ15 N were in the ranges of 5.97 to 10.97,-21.76‰ to-13.14‰ and 2.13‰ to 8.08‰, respectively, implying that sedimentary organic matter in Sanggou Bay was the mixture of marine phytoplankton, terrestrial and maricultural sources. A simple mixing model based on δ13 C was applied and the results indicated that the relative contributions of organic carbon sources in Sanggou Bay followed the order kelp(36.6%) ? marine phytoplankton(28.7%) ? shellfish bio-deposition(23.8%) ? terrestrial input(10.9%). Surface sediments in Sanggou Bay were dominated by mariculture-derived organic carbon, which on average accounted for 60.4% of TOC.  相似文献   
9.
本文主要研究丹东变电井地下流体水位数字化改造后的十五数字资料,对变电井水位的正常动态、干扰动态、同震异常进行全面的分析和总结,识别水位变化中的正常动态和干扰动态,分析干扰动态原因及解决办法,总结典型同震异常特点,以提高利用地下流体观测地震的监测效能。  相似文献   
10.
第三代相干体算法(C3算法)具有分辨率高、压制噪声能力强的优点,但是该算法需要计算协方差矩阵的特征值,所以耗时较多。为提高大矩阵特征值分解的运算速度,提出了一种估计最大特征值的快速收敛算法,通过运用A2k矩阵的迹来构造一种收敛速度更快的特征值估计方法,并给出了这种方法的误差估计表达式,实现计算精度的有效控制。文中还讨论了地震数据体边缘补地震道方法,解决了将递推算法应用到平面方向时空间窗越过边界的问题。实例表明,本算法的计算效率明显高于常规的C3算法。  相似文献   
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