温度、光照、氮含量对微绿球藻生长及脂肪酸组成的影响   总被引：21，自引：1，他引：21  

蒋霞敏 《海洋科学》2002,26(8):9-13

报道了环境因子对微结球藻（Nannochloropsis oculata)的生长速率及脂肪酸组成的影响，结果表明：微绿球藻具有较快的生长速度，且富含16：1（n-7)和20：5（n-3)(EPA)。适温范围为0－30℃，最适温度为20℃，温度对脂肪酸组成的影响较明显，EPA在20摄氏度时最高，30℃时急剧下降，生长较适宜光强为5000－7000lx，但在1000lx时EPA产率最大；氮含量为10mg/L时生长速度最快，但此时EPA含量较低。  相似文献   

光照强度对水华微囊藻(Microcystis flos-aquae)群体大小增长的影响   总被引：2，自引：1，他引：1  

张艳晴  杨桂军  秦伯强  周健  许慧萍  王颖  吴雅丽 《湖泊科学》2014,26(4):559-566

大量微囊藻群体的形成和聚集是微囊藻水华形成的重要条件.光照强度是影响微囊藻生长的重要因素之一.为了了解光照强度对水华微囊藻(Microcystis flos-aquae)群体大小增长的影响,以太湖微囊藻水华优势种之一的水华微囊藻作为研究对象,开展了不同光照强度对水华微囊藻群体大小增长的影响研究.共设置5个不同光强处理组,依次为G1:2000 lx;G2:4000 lx;G3:8000 lx;G4:16000 lx;G5:变化光照强度(模拟野外光强).实验期间,G1~G5组大于100细胞群体的平均大小分别为255、480、630、763和662 cells/群体.胞外多糖含量分析显示水华微囊藻形成的群体越大,胞外多糖含量越高.结果表明,低光照强度不利于太湖水华微囊藻群体大小的增长,而变化光照强度和高光照强度有利于水华微囊藻群体大小的增长.研究结果解释了太湖夏季野外变化光照强度和高光照强度有利于微囊藻水华形成的原因.  相似文献   

太湖：过去、现在和将来     

Mike Dickman  濮培民  郑长苏 《湖泊科学》1998,10(S1):75-84

The presence of roads, farm house foundations, wells and Liangzhu period cultural relics in the bottom of Lake Taihu attest to the fact that this shallow depression was probably dry between 4 and 5 thousand years ago. This interpretation is corroborated by the sudden disappearance of algal pigments at sediment depths carbon-14 dated at 4-5 thousand years before present.In winter, the stronger winds are predominantly from the northeast. These winds result in a powerful counterclockwise current that transports lake sediments and has altered the very shape of the lake over the last 300 years. Winds produce a complex mixing pattern in Lake Taihu with storm induced sediment deposition occurring near the lake''s center.During approximately 240 days of the year, the wind blows across Lake Taihu with sufficient force to mix it to its bottom. As a result, this polymictic lake rarely becomes anoxic and dissolved oxygen at the mud water interface is maintained at or above 4 mg·l^-1. The consequences of this high dissolved oxygen are quite impressive as high organic loading to the lake would otherwise render its bottom waters anaerobic killing many of its natural inhabitants.Because suspended solids reduce (attenuate) light penetration, the major primary production takes place in the top metre of the lake (mean Secchi Transparency-0.25 m). Suspended clays are slow to settle and wind mixing keeps fine-grained suspended solids in suspension in all but the most quiet backwaters of the lake.In the recent past about 23 000 metric tonnes of phytoplankton were produced in Lake Taihu. This large production represents only about 5% of the total influx of organic material entering the lake. In summer and fall, cyanobacteria such as Microcystis spp. and Anabaena spp. dominate most of the lake. Recently, however, mixotrophic flagellates displaced cyanobacteria as the dominant algae in parts of Lake Taihu with high bacteria and high suspended solids (e.g. Wuli and Meiliang Bay). In the future, facultative heterotrophs may come to dominate an ever larger portion of the lake waterc column.  相似文献   

偏最小二乘（PLS）—极谱络合吸附催化波同时测定轻稀土La,Ce,Pr,Nd,Sm,Eu     

张凯  张凤君 《世界地质》1999,18(3):96-99

运用２７３Ａ电化学系统确定了偏最小二乘计极 法同时测定Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ分量的最佳体系为：０．０８ｍＬ的ＸＯ、ＰＨ＝４．０的ＨＡＣ－ＮａＡＣ缓冲溶液６ｍＬ。６种轻稀土在１．０＊１０＾－７－８．０＊１０＾－６ｍｏｌ＝／Ｌ的浓度范围内有良好的线性关系,每种稀土元素的检出限为１．４＊１０＾－８ｍｏｌ／Ｌ。６种轻稀土的相对标准偏差为６．７％－１２．８％。  相似文献   

遥感影像图片制作新技术   总被引：1，自引：1，他引：0  

李进来  赖吉生 《国土资源遥感》1999,10(2):60-62

介绍了一种新的图片制作技术---激光数码成像技术,阐述了激光数码成像仪的成像原理,分析了输出图像的特点,评价了激光数码技术的应用效果及应用前景。  相似文献   

天体物理非线性问题初探-活动星系核的光变及引力的局部近似     

何谨 《天文研究与技术》1999,(1)

展示活动星系核研究和引力研究中的一些难点,揭示了某些天体的光变存在分形结构的可能性。我们提出了活动星系核的中心黑洞具有某种随机微活动性的假设,该假设可解释活动星系核的一些观测现象。我们发现Ｗｅｉｅｒｓｔｒａｓ函数的分形图形可以用来很好地拟合ＯＪ２８７的短时标光变。一个用Ｗｅｉｅｒｓｔｒａｓ函数构造的分形曲线与ＯＪ２８７的历史光变的线性相关系数达到了０．７３。我们计算了ＯＪ２８７光变曲线的计盒维数,信息维数和关联维数,结果表明,这些维数均大于１。我们研究了两个活动星系核（ＯＪ２８７和３Ｃ３４５）的历史光变,发现在星等和这两个物体滞留在这个星等之下的时间长度的对数之间存在线性关系。这种关系可能源于光变的分形结构。我们提出,空时点及附于该点的一个标架与Ｍｉｎｋｏｗｓｋｉ空间上的一个３阶反对称张量场对应。场中的张量取自于一个固定的张量集合。我们得到了Ｒｉｅｍａｎｎ正则坐标下引力场的一个级数表示式。我们还计算了Ｒｉｃｃｉ张量的线性近似和一级非线性近似。这有利于强引力场下的局部非线性结构分析。期望对于引力的进一步研究,通过非线性科学这门新方法的桥粱,沟通极端天文现象与基本引力相互作用之间的鸿沟  相似文献   

桑沟湾水域浮游植物的光量子产值   总被引：3，自引：0，他引：3  

吕瑞华  夏滨  毛兴华 《海洋与湖沼》1999,30(1):52-57

于1989－1990年对山东半岛的桑沟湾水域进行了综合调查,利用对自然水域现场测量的方法,对浮游植物兀合色素对光的吸收及其光量子产值进行了4个季度月的测量和计算,目的是研究这种浅海养殖生态系统初级生产过程中的能量流动状况。结果表明,该海区光量子产值的范围为0.189×10-2molC／E－6．019×10-2molC／E;浮游植物吸收的光能占海面总吸收光能的0.9％－5.5％;浮游植物的光利用率为0.026％－0.101％,与其他海区相比,较为偏低。  相似文献   

光照强度对番红砗磲外套膜颜色变化的影响     

刘二田  何园园  顾志峰  石耀华  王爱民  刘春胜 《海洋科学》2021,45(1):70-75

以蓝色、棕黄色和绿色三种不同外套膜颜色的番红砗磲(Tridacna crocea)为实验对象,设置5000 lx、10000 lx和15000 lx三组光照强度,探究了番红砗磲外套膜颜色变化与光照强度的相关性.结果表明:(1)在不同光照强度下,蓝色个体外套膜颜色加深,棕黄色个体颜色变化不大,而绿色个体外套膜颜色变浅.(...  相似文献   

Development of a Vector-Based Method for Coastal Bluffline Mapping Using LiDAR Data and a Comparison Study in the Area of Lake Erie     

Yunjae Choung  Rongxing Li  Myung-Hee Jo 《Marine Geodesy》2013,36(3):285-302

This paper introduces a new method for bluffline extraction based on analysis of surface normal vectors derived from a 2.5-dimensional Delaunay triangulation network generated using a set of LiDAR points. The developed method has been implemented and tested for the extraction of blufflines in a section of the Lake Erie coastline near Painesville, Ohio. Comparison of the research results with those generated by a method for bluffline extraction based on slope information along elevation profiles on transects shows an improvement in both horizontal and vertical accuracies in situations where the bluff has a relatively sharp edge formation.  相似文献   

Quantifying water stress effect on daily light use efficiency in Mediterranean ecosystems using satellite data     

《International Journal of Digital Earth》2013,6(6):623-638

ABSTRACT

The capacity of six water stress factors (ε′_i) to track daily light use efficiency (ε) of water-limited ecosystems was evaluated. These factors are computed with remote sensing operational products and a limited amount of ground data: ε′₁ uses ground precipitation and air temperature, and satellite incoming global solar radiation; ε′₂ uses ground air temperature, and satellite actual evapotranspiration and incoming global solar radiation; ε′₃ uses satellite actual and potential evapotranspiration; ε′₄ uses satellite soil moisture; ε′₅ uses satellite-derived photochemical reflectance index; and ε′₆ uses ground vapor pressure deficit. These factors were implemented in a production efficiency model based on Monteith’s approach in order to assess their performance for modeling gross primary production (GPP). Estimated GPP was compared to reference GPP from eddy covariance (EC) measurements (GPP_EC) in three sites placed in the Iberian Peninsula (two open shrublands and one savanna). ε′_i were correlated to ε, which was calculated by dividing GPP_EC by ground measured photosynthetically active radiation (PAR) and satellite-derived fraction of absorbed PAR. Best results were achieved by ε′₁, ε′₂, ε′₃ and ε′₄ explaining around 40% and 50% of ε variance in open shurblands and savanna, respectively. In terms of GPP, R²?≈?0.70 were obtained in these cases.  相似文献