Silicon limitation on primary production and its destiny in Jiaozhou Bay, China——Ⅳ：Study on cross-bay transect from estuary to ocean

The authors analyzed the data collected in the Ecological Station Jiaozhou Bay from May 1991 to November 1994, including 12 seasonal investigations, to determine the characteristics, dynamic cycles and variation trends of the silicate in the bay. The results indicated that the rivers around Jiaozhou Bay provided abundant supply of silicate to the bay. The silicate concentration there depended on river flow variation. The horizontal variation of silicate concentration on the transect showed that the silicate concentration decreased with distance from shorelines. The vertical variation of it showed that silicate sank and deposited on the sea bottom by phytoplankton uptake and death, and zooplankton excretion. In this way, silicon would endlessly be transferred from terrestrial sources to the sea bottom. The silicon took up by phytoplankton and by other biogeochemical processes led to insufficient silicon supply for phytoplankton growth. In this paper, a 2D dynamic model of river flow versus silicate concentration was established by which silicate concentrations of 0.028–0.062 μmol/L in seawater was yielded by inputting certain seasonal unit river flows (m³/s), or in other words, the silicate supply rate; and when the unit river flow was set to zero, meaning no river input, the silicate concentrations were between 0.05–0.69 μmol/L in the bay. In terms of the silicate supply rate, Jiaozhou Bay was divided into three parts. The division shows a given river flow could generate several different silicon levels in corresponding regions, so as to the silicon-limitation levels to the phytoplankton in these regions. Another dynamic model of river flow versus primary production was set up by which the phytoplankton primary production of 5.21–15.55 (mgC/m²·d)/(m³/s) were obtained in our case at unit river flow values via silicate concentration or primary production conversion rate. Similarly, the values of primary production of 121.98–195.33 (mgC/m²·d) were achieved at zero unit river flow condition. A primary production conversion rate reflects the sensitivity to silicon depletion so as to different phytoplankton primary production and silicon requirements by different phytoplankton assemblages in different marine areas. In addition, the authors differentiated two equations (Eqs. 1 and 2) in the models to obtain the river flow variation that determines the silicate concentration variation, and in turn, the variation of primary production. These results proved further that nutrient silicon is a limiting factor for phytoplankton growth. This study was funded by NSFC (No. 40036010), and the Director's Fund of the Beihai Sea Monitoring Center, the State Oceanic Administration.     

冻藏龙眼果皮细胞膜透性、PPO活性和酚类物质含量的变化

将“油谭本”龙眼在-40℃条件下进行速冻，然后转入-18℃恒定低温冷库中冻藏180d。测定了龙眼果实速冻时的冻结曲线、冻藏过程中果皮细胞膜渗透率、果皮内PPO的活性和总酚含量的变化情况。试验结果表明，-40℃的冷冻温度即可满足速冻要求；冻藏可以有效地抑制果皮内PPO的活性，果皮细胞膜渗透率和总酚含量的变化较小，能够较好地保持果实的外观品质。     

西藏搭格架热泉型铯矿床矿物学与矿石组构特征及地质意义

在查明搭格架铯矿床产出的地质背景、成矿阶段及其年龄、地球化学与同位素组成的基础上,本文较为系统地研究了硅华的矿物学与组构特征,加深了对硅华形成演化过程的认识.研究表明成矿早期,矿石中存在大量的石英,晚期全为蛋白石.粒状蛋白石自早到晚均有出现,胶状蛋白石主要出现于晚期.早期矿石出现脱水造成的菜花状、粗粒块状与粗大孔隙状构造及溶蚀结构.晚期出现细粒块状与细小孔隙状构造.在第3阶段存在硅藻Denticula属,体现出低温阶段的特征.由早到晚,矿石的SiO2呈降低趋势,而(Na2O Al2O3 K2O CaO)与Cs2O呈升高趋势,是随着矿石中SiO2有序度的降低而其它成分被保留在晶格中所致.     

海洋肽类活性物质的研究概况

现代海洋生物活性物质的研究始于６０年代 ,迄今为止已经发现具有重要生理及药理活性的化合物达２０００多种。近１０多年来 ,我国的海洋药物研究与开发也取得很大的进展。据初步统计 ,我国近海已发现具有药用价值的海洋生物达７００多种。许多具有免疫、抗炎、抗肿瘤、抗病毒以及作用于心血管系统和神经系统的活性物质先后被分离提纯 ,并且对其中结构特殊、作用强烈的物质进行了人工合成或结构改造 ,以求开发可供临床应用的新药。从海洋生物中得到的生物活性物质种类繁多，包括有多肽类、萜类、生物碱类、大环聚酯类、聚醚类等化合物。其中…     

河口Si输运过程研究

基于拉格朗日余流及其输运过程的一种三维空间弱非线性理论，进一步假定Ｓｉ在河口的无因次化学转移项量级为ｋ＾２，给出了Ｓｉ的长期输运方程。对于一种二维模型河口，数值求解了零阶天文潮，欧拉余流、斯托克斯漂移、拉格朗日余流和盐度的分布；分别计算了平均逼留时间为１３，３０，６０，１８０ｄ等所对应的Ｓｉ浓度分布；给出了Ｓｉ－ｓ相关图，讨论了河口中Ｓｉ的保守性问题。     

长江生源要素的输出通量

长江是太平洋西岸最大的河流,它源源不断地向东海输送大量物质,是舟山渔场的重要化学物质基础,不仅对长江口海区以至整个东海有举足轻重的影响,对太平洋的影响也是不可忽视的。本文报道颗粒有机碳(POC)、溶     

中国海洋天然活性物质开发新技术21世纪发展战略

海洋天然活性物质是指海水、沉积物和在海洋环境生存的动植物体中所含有的具有生理活性的物质，一般情况下则指海洋生物体中的生物活性物质。几千年来，人们一直在探索和发现这类物质，并扩大它的应用，在当今人类回归大自然的浪潮中，海洋天然活性物质的开发成了国际热点之一 [1～ 9]。本文在分析了国外的进展，我国的水平与差距后，提出了我国海洋天然活性物质开发新技术的发展战略。     

甘糖酯对大鼠尿激酶型纤溶酶原激活物活性的诱导作用

为了研究甘糖酯对大鼠体内尿激酶型纤溶酶原激活物 (urokinase PlasminogenActivator,u PA)活性的影响 ,采用溶解圈中和抑制法和发色底物法检测了大鼠口服甘糖酯后体内u PA活性的变化情况。结果表明 :甘糖酯可提高大鼠体内血液的纤溶活性 ,主要表现为 u PA活性升高。以不同剂量的甘糖酯连续喂药 10 d后 ,发现喂药组大鼠 u PA活性明显高于对照组 ,喂药组大鼠血浆 u PA活性升高同喂药剂量正相关 ,在 0～ 10 0 mg/ kg的剂量范围内 ,随喂药剂量增加而升高。提示在一定的剂量范围内甘糖酯可提高大鼠体内 u PA活性 ,激活纤溶系统 ,提高血液纤溶活性 ,表现出良好的抗栓作用     

山东省海积型硅砂资源开发的思考

本文就山东省海积型硅砂资源的开发应用现状及今后进一步的开发应用进行了探讨。