光照强度对海洋微藻脂肪含量及脂肪酸组成影响的研究

近年来，海洋微藻脂肪酸组成的研究及其应用越来越受到国内外科学家的重视。高度不饱和脂肪酸(PUFA)，特别是长链的n-3 PUFA，如二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)对海洋动物和人类都具有营养学和医学上的价值。在海洋微藻的培养过程中，光照强度是海洋微藻生长的条件之一，光线的明与暗，光度的强与弱，不仅对微藻的生长速率、产量有影响，而且对其脂肪含量和脂肪酸的组成也有影响(Teshima et al.，1983；Thompson et al.，1990； Renaud et al., 1991)。 作者在以往研究的基础上，选择了3种有代表性的海洋微藻：(1)小球藻Chlorella sp-2(李荷芳等，1999)，此藻脂肪酸中EPA含量高、且不含DHA；(2)球等鞭金藻(Isochrysis galbana)，该藻DHA含量较高，但几乎不含EPA；(3)前沟藻(Amphidinium sp.)的EPA、DHA含量均高。将以上3种微藻作为原料，在不同的光照强度下进行培养，测定并分析藻体中的脂肪含量和脂肪酸组成的变化，从而了解光强对海洋微藻脂肪含量及其脂肪酸组成的影响。     

温度、光强和盐度对鹧鸽菜幼体生长发育的影响

从野外采集鹤鸪菜Ｃａｌｏｇｌｏｓｓａｌｅｐｒｉｅｕｒｉｉ（Ｍｏｎｔ．）Ｊ．Ａｇ．幼体，在室内控制条件下，以温、盐、光等不同条件进行模拟培养试验。所获得的数据经生物统计检验表明：鹧鸪菜幼体生长最适水温为２３℃；光照强度为４０００ｌｘ；海水盐度为１８。此结果与我们多年来在汕头港内观察鹧鸪菜的生长及其季节变化相似。     

A new approach for predicting the extreme response of structures

In this article a method to estimate the mean upcrossing intensity, μ(u), of a stochastic process is proposed. It is assumed that the stochastic process is a sum of a Gaussian process and a second-order correction term. The method is based on the two-dimensional Saddlepoint approximation. The accuracy of the method is tested on processes having analytical solutions for μ(u). Numerical examples are given where the stochastic process represents (i) the horizontal response of a floating offshore structure in a Gaussian sea, and (ii) the response of a structure subjected to a Gaussian wind velocity process. In addition, the estimates are compared to empirical upcrossing intensities of simulated responses. For case (ii), the obtained μ(u) estimates are compared to estimates obtained by numerical integration.     

Phytoplankton production in two east coast estuaries: Photosynthesis-light functions and patterns of carbon assimilation in Chesapeake and Delaware Bays

Chesapeake Bay is a large and productive estuary that has received close scrutiny in recent years because of indications that its water quality and biota have been damaged by man's activities. Data on primary production for the estuary as a whole, however, are surprisingly sparse. We describe here the distribution of photosynthetic carbon assimilation by phytoplankton in Chesapeake Bay, and relate productivity patterns to hydrographic characteristics of the estuary. Between March 1982 and April 1983, a series of four cruises was conducted on Chesapeake Bay, and two cruises on the urbanized Delaware Bay for comparison. The upper Chesapeake and Delaware were highly turbid with high concentrations of suspended particulate matter and dissolved inorganic nutrients. Low chlorophyll concentrations were usually found in these areas of high turbidity, despite the abundance of nutrients, suggesting light limitation. Application of Wofsy's (1983) model of phytoplanton growth confirmed this suggestion. Chlorophyll and productivity maxima usually occurred seaward of the turbidity maxima where light penetration increased and suffient nutrients were present to support active phytoplankton growth. Further seaward of the chlorophyll maxima in the Chesapeake, the photic zone depth increased, concentrations of nutrients decreased, and phytoplankton biomass decreased, suggesting that nutrient availability, rather than light, controlled phytoplankton growth in the lower portion of the estuary. In contrast to the Chesapeake, Delaware Bay was more turbid, had generally higher nutrient concentrations, and was lower in phytoplankton productivity. The chlorophyll maxima and region of rapid phytoplankton growth occurred further toward the lower estuary and shelf regions in Delaware Bay because the high turbidity extended further seaward. Nutrients were never depleted at the shelf end of the estuary sufficiently to retard phytoplankton growth. Photosynthesis-irradiance (P-I) curves from simulated in situ and constant intensity incubations showed a strong correlation of the light-limited slope (a^B) with the light-saturated rate ( ) on each cruise. Spatial variations in corresponded to patterns of phytoplankton abundance, as did integral production (PP) and carbon-based growth rates (μ_C, μ_m), and photosynthetic parameters varied significantly with temperature.     

礁膜配子放散条件的研究

本文报道了礁膜配子的放散与温度、光照、比重的关系。结果表明，自然海区的礁膜在白天大量放散配子。配子放散的适宜温度为１９－２１℃；光照为２０００－５０００ｌｘ时能促进配子大量放散出来；配子放散的适宜比重为１．０５－１．０２５；这些研究结果将为礁膜人工育苗提供一些科学依据。     

哀牢山-红河断裂带中段应变分析

对哀牢山—红河断裂带中段和平—水塘剖面、墨江—元江剖面和其它地段的岩石应变及磁组构进行了分析，表明应变强度的校正磁各向异性度PJ从断裂带向西至三叠系明显降低，变形强度向西迅速减弱。磁化率椭球体主轴展布反映出剪切带内、外变形方式的改变。剪切带内，以水平走滑运动为主；向西则以水平缩短为主。在应变分析中，对断裂带内的S—C组构两组面理夹角、杏仁体和石榴石应变标志体进行了测量，结果显示，剪切带内的磁组构和岩石组构间关系较差。此外，还对这两条剖面中的三叠系进行了应变和磁组构分析，找出了它们与磁化率椭球体对应轴率间的相关性。     

南海西部浮游有孔虫记录的MIS 3期表层海洋环境变化

对南海西部越南岸外上升流区17954-2站浮游有孔虫属种组合变化、浮游有孔虫氧同位素、AMS14C测年的分析以及浮游有孔虫表层海水温度、温跃层转换函数的研究结果表明:在MIS3期,南海西部表层海水温度大体呈现暖-冷-暖的变化趋势;温跃层深度由浅到深阶段性变化;短时间尺度上温度与温跃层发生幅度较大的快速变化。暖事件（IS）对应于浮游有孔虫暖水种、混合层属种含量的增加,冷水种、温跃层属种含量的减少以及冬夏SST的升高;冷事件则与之相反。表层海水生产力亦大致呈现3个阶段（61～51ka,51～42ka和42～32ka）的变化,在千年尺度的快速气候事件中,暖事件对应浮游有孔虫生产力属种含量降低,冷事件对应升高。此外,在MIS3内部分暖事件（IS6和IS11～13）表现出表层海水温度降低,温跃层深度变浅和表层海水生产力升高的状况,表明该区此时上升流的存在,其形成原因推测是由于东亚夏季风加强的结果。     

基于小波变换的单频GPS快速精密定位整周模糊度的解算

对于GPS短基线,载波相位双差观测量已基本消除了卫星轨道误差、钟差、大气折射误差等系统偏差的影响,主要包含距离观测量信息及随机测量误差,其中测量误差是高频的测量噪声,小波变换可将GPS载波相位双差观测量中的观测噪声(高频部分)分解出来。本文利用Coiflets小波基函数对GPS快速定位的原始载波相位双差观测量进行5层分解,通过重构第5层低频系数获得去除噪声的"干净"的载波相位双差观测量,然后利用"干净"的双差观测量进行最小二乘参数估计,以减小测量噪声对GPS快速定位病态方程解的扰动。计算结果表明该方法能够显著提高GPS快速定位中模糊度浮点解的精度,仅利用几个观测历元的数据就可以准确地固定模糊度。     

成像光谱矿物填图精度兼与矿物丰度关系初探

成像光谱遥感技术在岩石矿物识别和矿物填图方面发挥着越来越大作用,而成像光谱矿物填图的精度问题一直是研究的焦点。文章利用高光谱数据HyMap对新疆东天山地区的矿物填图结果,通过引入矿物填绘分布强度的概念,探索性的分析了成像光谱矿物填图与填绘矿物丰度的关系。