凡纳滨对虾幼体不同生长发育时期应答氨氮胁迫的敏感性研究

凡纳滨对虾(Litopenaeus vannamei)是世界上最重要的对虾养殖品种之一。为比较凡纳滨对虾不同生长发育时期应答氨氮胁迫的敏感性差异,作者对其不同生长发育时期24 h半数致死浓度(LC_(50))进行测定,并分析其胁迫效应。结果表明,24 h LC_(50)值在虾的不同生长发育时期差异显著(P0.05),不同时期凡纳滨对虾的LC90与LC_(50)变化趋势相同。在溞状幼体Ⅱ期(Z2)LC_(50)值最低,为17.811 mg/L,在仔虾第V期(P5)时,LC_(50)值最高,为44.808 mg/L。根据LC_(50)和LC90的变化趋势可以看出,仔虾比幼体期的耐受性强。本试验结果不仅为凡纳滨对虾不同生长发育时期的苗种培育提供了重要的基础数据,而且为凡纳滨对虾耐氨氮品系选育提供了重要指导。     

墨西哥湾盐岩分布对油气成藏的控制作用

墨西哥湾在侏罗纪时成为半封闭海,沉积了大套的含膏盐岩层,经历4个阶段的演化构建出了不同形态的盐岩体,进而控制了该区的地层、构造形态以及圈闭类型。该区含膏盐岩层系不仅是良好的烃源岩,而且是良好的储集层和盖层,因此,研究该区盐岩层的构造演化、成因类型及控制因素对了解该区的油气成藏有着重要的作用。     

Distribution, abundance, and growth of larval tautog, Tautoga onitis, in Buzzards Bay, Massachusetts, USA

Tautog, Tautoga onitis, is an abundant species of fish in estuaries of the northeastern United States. Planktonic tautog larvae are abundant in summer in these estuaries, but there is little information on rates of growth of tautog larvae feeding on natural assemblages of food in the plankton. We examined abundance and growth of larval tautog and environmental factors during weekly sampling at three sites along a nearshore‐to‐offshore transect in Buzzards Bay, Massachusetts, USA during summer 1994. This is the first study of a robust sample size (336 larvae) to estimate growth rates of field‐caught planktonic tautog larvae feeding on natural diets, using the otolith daily‐growth‐increment method. The study was over the entire summer period when tautog larvae were in the plankton. The sampling sites contrasted in several environmental variables including temperature, dissolved oxygen (DO), and chlorophyll a concentration. There was a temporal progression in the abundance of tautog larvae over the summer, in relation to location and temperature. Tautog larvae were first present nearshore, with a pronounced peak in abundance occurring at the nearshore sites during the last 2 weeks in June. Larvae were absent at this time further offshore. From late June through August, larval abundance progressively decreased nearshore, but increased offshore although never approaching the abundance levels observed at the nearshore sites. The distribution and abundance of tautog larvae appeared to be related to a nearshore‐to‐offshore seasonal warming trend and a nearshore decrease in DO. Otoliths from 336 larvae ranging from 2.3 to 7.7 mm standard length had otolith increment counts ranging from 0 to 19 increments. Growth of larval tautog was estimated at 0.23 mm·day^?1, and length of larvae prior to first increment formation was estimated at 2.8 mm indicating that first increment formation occurs 3–4 days after hatching at 2.2 mm. Despite spatial and temporal differences in environmental factors, there were no significant differences in growth rates at any of three given sites over time, or between sites. Because larval presence only occurred at a narrow range of temperature (17–23.5 °C) and DO (6.5–9.3 mg·l^?1), in situ differences in growth did not appear to be because of differences in larval distribution and abundance patterns relative to these parameters.     

锈斑蟳(Charybdis feriatus)室内人工育苗的研究

盐度30、温度27.5～29.5℃、pH7.8～8.6的条件下,投喂扁藻(10×104mL-1)、轮虫(20mL-1～50mL-1)、卤虫无节幼体(1mL-1～30mL-1)及卤虫成体(0.1mL-1),进行锈斑蟳室内人工育苗试验。结果表明:溞状幼体Z1期2～4d,存活率100%;Z2期2～3d,存活率74.0%～78.0%;Z3、Z4、Z5期各3d,存活率分别为37.5%～59.0%、26.5%～43.0%、22.0%～36.7%;Z6期3～5d,存活率19.0%～26.3%;大眼幼体5～6d,存活率11.0%～11.5%;Ⅰ期幼蟹(蟹苗)存活率4.5%～5.0%,整个育苗过程共计20～26d。     

通辽地区玉米分期播种试验及适时播种期探讨

文章探究了播种期对气候资源利用及玉米产量的影响,分析了气候变暖对玉米适宜播种期的影响。通过分期播种试验确定通辽地区玉米适宜播种期。早播玉米与迟播玉米虽然在播种—出苗,出苗—七叶,七叶—拔节期及乳熟期—成熟期间的间隔天数及≥10℃积温差异较大,但全生育期天数及总积温差异较小;早播玉米部分生育期间隔时间增长,迟播玉米播种—出苗期间隔时间缩短。为充分利用气候资源提供科学依据。     

东营市典型旱涝年环流形势分析

利用100hPa和500hPa历史资料分析了东营市典型旱涝年同期和前期的环流形势特点，结果表明，2000和2001年的环流形势比较接近气候上的干旱年环流特点，与实况降水量偏少对应较好。     

新疆艾比湖精河入湖口退化湿地恢复过程中浮游植物群落的变化

精河入湖口湿地是新疆艾比湖湿地的重要组成部分.本文通过空间序列代替时间序列的方法,对艾比湖精河入湖口退化湿地不同恢复期的浮游植物群落特征进行分析,结果表明,恢复早期和中期硅藻种类最多,绿藻在密度上占明显优势,恢复近期硅藻为主要优势类群.恢复早期及自然区浮游植物群落结构较为稳定,中期和近期群落结构不够稳定,易受外界环境的...     

构造应力场转换与界面成矿

构造应力场转换与界面成矿是成矿作用动力学的关键和核心,它决定着矿床的形成与分布。构造应力场转换表现为不同层次的构造叠加作用和韧－脆性变形的转换,以及同一构造层次不同时期、不同构造部位应力的转换。成矿界面是物理化学条件突变的空间和场所,是成矿流体停积而发生矿质沉淀、富集、成矿之所在,主要表现为岩性、温度、压力、ｐＨ、Ｅｈ等方面的突变性,其力学性质及岩石的物理性质、化学成分是控制矿体形态、产状、规模,矿石组构,甚至矿石成分的重要因素。它们与构造应力作用大多有相关性,而与构造－流体的脉动性及空间分布关系尤为密切。作者在矿石构造多呈张裂状态,而矿脉、矿体及蚀变带多表现为压剪变形性质的地区详细填图成果基础上,探讨了构造－流体脉动规律与界面成矿机制,提出剪压变形构造岩相向剪张变形构造岩相转换而发生金属硫化物成矿作用的新认识。     

鄂尔多斯盆地延长矿区延长组流体包裹体特征

流体包裹体在划分油气运移充注期次、确定油气藏形成时间等方面均有重要的应用价值。笔者通过镜下观察流体包裹体的发育产状, 划分其类型, 描述其特征, 并与成岩作用相结合来确定包裹体形成期次。通过对与烃类共生的盐水包裹体进行均一化温度测试, 结合其他相关地质资料, 认为延长矿区延长组流体包裹体的均一温度集中分布在105～125℃范围内, 且包裹体均一温度有随埋深增加而增高趋势。对比研究区埋藏史、地热史分析得出, 延长矿区至少存在一期主要的油气成藏期次, 发生在距今100～110 Ma, 即早白垩世晚期, 为该区主要的油气成藏期。     

长乐-南澳构造带变质变形期次划分及时代厘定

长乐-南澳构造带中发育有晚侏罗世早期、晚侏罗世晚期及早白垩世等3个不同时期的变质变形侵入岩。不同期次侵入岩具有不同的变质变形特征。根据糜棱岩的空间分布、糜棱叶理的切割关系等,表明构造带在中生代发生了3期韧性剪切变形及相关的动力变质作用。第一期为（北西西－南东东向）右行－推覆韧性剪切,具低角闪岩相变质、深部构造层次长石相...