The relationship between cyanobacteria and environmental factors in the Bering Sea

During the first Chinese Scientific Expedition to the Arctic in July - September 1999, cyanobacteria in the Bering Sea were measured by epifluorescence microscopy. Cyanobacterial abundance varied from 0 to 7. 93 × 103 cell/ml and decreased along a northerly directed latitudinal gradient in horizontal distribution. Cyanobacteria did not occur at station Bl - 12 (north of 60 °N). Vertically, high cya-nobacterial abundance appeared in the upper 25 - 50 m and decreased rapidly below 50 m. There were no cyanobacteria at the 150 m. Seawater temperature and NH4+ -N are suggested to affect the distribution of cyanobacteria.     

Vertical properties of nutrients and oxygen under tempeuature-salinity structure of the Bering Basin in July 1999

The China R/V Xuelong went on the first Arctic scientific cruise, and we obtained 271 hydro-chemical samples from 22 deep-sea stations in the Bering Basin in late July, 1999. Here we describe vertical properties of silicate [Si] , dissolved inorganic nitrogen [DIN] or [N] (nitrate plus ammonium plus nitrite) , phosphate [P] and oxygen [ O2 ] in seawater under potential temperature-salinity structure. The seasonal stratification in the summer and the water exchanges of the North Pacific Ocean over the Bering Basin resulted in that the four layers of vertical structure with two thermoclines may be found. Vertical [Si] and [N] and [P] profiles show that the nutrients are consumed mainly in ≤50 m and the order of deficient nutrients is [Si] the first, [N] the second and [P] the third. The [N] and [P] increase with depth downward to about 500 m and then both decrease, but the [Si] increases from 150 m to 2000 m or the bottom. In ≥ 150 m the [ O2 ] decreases, which is related with both [P] and [N] increasin     

Application of BP Neural Network Model in Fracturing Productivity Prediction of Fuyu Tight Oil Reservoir in Jilin Oilfield

<正>1 Introduction Oil resources in tight reservoirs are widely distributed in China.Tight oil reservoirs have been discovered in Songliao Basin,Bohai Bay,Qaidam Basin,Tuha Basin,Sichuan Basin,etc.However,such oil reservoirs have poor physical properties.Conventional vertical wells are hard to bring about economic benefits,and the horizontal well     

近年国际高等地理教育研究现状与热点分析

本文以地理教育领域的权威刊物《高教地理学杂志》(Journal of Geography in Higher Education)1999-2018年刊登的文献作为研究对象,运用ENDNOTE、EXCEL、VOSVIEWER等软件梳理了国际高等地理教育领域研究者的国家与地区分布、研究机构、核心作者和研究热点等方面的数据。结果表明:在国际高等地理教育领域,发文量最多的国家为英国、美国,以发达国家为主;较高产的机构为切斯特大学、普利茅茨大学;最具有学术影响力的作者来自英国;主要的研究热点包括地理信息系统、高校地理课程设置、野外实践和地理教育中的性别因素等。     

东喜马拉雅构造结高压基性麻粒岩成因与构造意义

东喜马拉雅构造结南迦巴瓦杂岩中存在典型的泥质、长英质和基性高压麻粒岩。但是,高压麻粒岩在南迦巴瓦杂岩中的分布范围、变质条件和变质时间是否存在空间上的变化并不明确。本文对南迦巴瓦杂岩西南部巴嘎地区的高压基性麻粒岩进行了岩石学和年代学研究。研究表明,巴嘎高压基性麻粒岩由石榴子石、单斜辉石、角闪石、斜长石、黑云母和石英组成,石榴子石变斑晶发育生长成分环带。识别出三期矿物组合：进变质矿物组合M1为石榴子石变斑晶核部及其矿物包裹体,包括石榴子石、石英、榍石和磷灰石;峰期矿物组合M2为变斑晶石榴子石边部和基质矿物,即石榴子石+单斜辉石+斜长石+角闪石+石英+金红石+熔体;退变质矿物组合M3呈冠状体或基质产出,其组合为角闪石+斜长石+单斜辉石+黑云母+石英+榍石。高压基性麻粒岩的峰期变质条件约为1. 5 GPa和915 ℃,具有顺时针P- T轨迹,退变质的早期和晚期分别为近等温降压和降温降压过程。高压基性麻粒岩在峰期条件下发生了明显的部分熔融,含~26%（体积）的熔体,其退变质和熔体结晶作用很可能发生在26~14 Ma。本文和研究区现有研究成果表明,东喜马拉雅构造结南迦巴瓦杂岩中的高压麻粒岩广泛分布,从东北部的加拉、直白和派乡延伸到西南部的巴嘎沟,形成了一条长度超过80 km的高压麻粒岩带。整个带中的高压麻粒岩具有类似的变质条件和持续时间,是印度大陆地壳平缓俯冲并经历了高温和高压变质与部分熔融的产物,构成了喜马拉雅造山带的加厚下地壳。大量高压麻粒岩强烈部分熔融产生的熔体可能为喜马拉雅淡色花岗岩提供了源区。     

具有非线性阻尼的圬工粗短柱在水平地震力作用下横截面上的压应力重分布(英文)

当合力作用在横截面核心之外时, 此截面的拉应力对于抗拉强度很低的圬工材料是不能承受的, 故应考虑压应力的重新分布。本文采用能反映激发和衰减的非线性Ｒａｙ／ｅｉｇｈ阻尼, 使控制方程无量纲化, 设振幅函数满足所有边界条件而简化控制方程为非齐次的Ｖａｍ ｄｅｒ Ｐｏｌ 方程, 得出其头两次渐近解, 再计算压应力重分布     

Variations of nutrient elements and its effect on ecological environment off the Changjiang estuarine waters

I~IOXThe water off the Changjiang EstUary is one of the ~ areas Of land-sea interactionwith complex current series and convening water masses, such as the Changjiang River diluting water fm the west, the HUangha As "dxed water frn the north as well as the TaiwanWad Current wedging fm the ~theaSt (Mao et al., 1963). TheSe water masses havePtovided rich nutrients for the gtDwth and rep~tion of planktons, leading to the fonnationOf the fishing ~ Off the Changjiang Estuary with active bio…     

锌镉还原法测量海水硝酸盐中锌卷的形状和面积

《海洋调查规范》(GB1 2 763.4 91 )的锌镉还原法规定 ,与 5 0mL水样起反应的锌卷面积是 30cm2 。在面积完全相同的条件下 ,将规定的 1 .5cm内径的圆筒式锌卷改成曲线内间距 2πa不小于 1 0mm的阿基米德螺旋式锌卷。用螺旋式测出白令海海水的硝酸盐浓度比圆筒式的高了约 1 1 %。采用天然海水或人工海水来配制高、中、低三档浓度的硝酸盐标准溶液 ,进行螺旋式锌卷的面积试验。结果证实 :《海洋调查规范》(GB1 2 763.4 91 )规定的反应面积没有过量。在 1- 1 7μM浓度范围内 ,两种锌片批号F980 72和 931 2 1 0 (上海化学试剂公司 )引起浓度的相对误差超过 1 0 %。     

基于Surpac的垂直断面资源储量估算方法研究与实现

结合传统资源储量估算方法垂直断面方法的实际特点, 以Surpac三维地质软件为基础, 建立和实现了三维软件环境下垂直断面资源储量估算方法的流程和相关程序, 并以安徽省某铁矿床为例进行了应用研究。研究结果表明:本次建立的流程和相关程序可以充分利用高精度三维地质环境进行传统方法资源储量估算, 提高估值精度;同时估值结果可用于对三维统计学储量估算方法进行对比验证, 具有十分显著的实用性和应用前景。     

D-InSAR技术在矿区形变监测中的应用研究

D-InSAR技术作为20世纪90年代发展起来的新型空间对地观测技术,凭借着全天候、全天时、高分辨率和连续空间覆盖的特点得到了广泛的应用.本文介绍了D-InSAR技术的基本原理和处理流程,以内蒙古营盘壕煤矿为例,利用哨兵数据,通过二轨差分干涉测量方法得到沉降数据.在ArcGIS中通过对沉降区域的提取、剖面分析和叠加分析...