超慢速扩张环境下超镁铁质岩系统的热液硫化物成矿机理以及启示     

曹红  孙治雷  刘昌岭  姜学钧  何拥军  黄威  尚鲁宁  王利波  张喜林  耿威  施美娟  李东义 《海洋学报》2018,40(4):61-75

西南印度洋63.5°E热液区是在超慢速扩张洋脊发现的首个超镁铁质岩热液系统。对取自该区的热液硫化物样品进行了系统的矿物学和地球化学分析，矿物学分析结果表明:该热液区硫化物为富Fe型高温硫化物，且经历了较深程度的氧化蚀变，大量中间态的Fe氧化物充填在硫化物矿物间的孔隙及内部解理中；这些硫化物相以白铁矿为主，其次是等轴古巴矿和少量铜蓝，缺乏黄铁矿、闪锌矿。据推断，该区的热液成矿作用分为4个阶段:低温白铁矿阶段→高温等轴古巴矿阶段→自形白铁矿阶段→后期海底风化阶段（少量铜蓝以及大量的Fe的羟氧化物）。与之相对应，地球化学分析结果表明这些硫化物的Fe含量较高（31.57%~44.59%），Cu含量次之（0.16%~7.24%），而Zn含量普遍较低（0.01%~0.11%）；微量元素较为富集Co（328×10-6~2 400×10-6）和Mn（48.5×10-6~1 730×10-6）。该区硫化物中较高含量的Fe、Co与超镁铁质岩热液系统相似，明显高于镁铁质岩热液系统。独特的热液硫化物矿物学特征和元素组成可能与该区普遍出露的地幔岩、橄榄岩蛇纹石化作用以及拆离断层的广泛发育的环境有关。  相似文献   

基于LAIC电场渗透和SAMI2模拟的地震-电离层扰动现象研究     

刘祎  周晨  赵正予  赵庶凡  张学民  孔建 《地震》2018,38(1):74-83

地震会造成电离层电子密度扰动。 基于三维电场渗透模型和SAMI2模型, 模拟地震发生前产生的异常电场对电离层电子密度的影响。 模拟结果表明, 地震前形成的附加电流会引起电离层产生异常电场, 且异常电场值与地震震级和地震发生时间有着明显的相关。 同时异常电场会使电子产生E×B漂移, 造成电子密度扰动。 随着时间的推移, 电子密度扰动逐渐减小且扰动区域会向着靠近磁赤道方向或远离磁赤道方向漂移。  相似文献   

Faecal indicator bacteria in New Zealand freshwater fish: a pilot study     

Sarah Coxon  Jon S Harding  Brent Gilpin 《新西兰海洋与淡水研究杂志》2019,53(3):470-479

Recent studies have suggested that poikilothermic animals, such as fish, may represent a previously overlooked source of the faecal indicator bacteria (FIB) used for the assessment of water quality. However, quantitative studies of FIB in poikilotherms are scarce. We investigated the presence of FIB in the faeces of five freshwater fish species. E. coli and enterococci were detected in 71 and 76% of faecal samples, respectively. Concentrations were highly variable, with maximum concentrations (2.1?×?10⁴ E. coli and 1.3?×?10⁶ enterococci per gram of faecal material) up to four orders of magnitude higher than present in the water column. FIB were not detected in faecal samples from marine fish. Our findings suggest that FIB ingested from the environment may be capable of replication within the fish gut, making fish a potential source and transport mechanism for FIB in New Zealand freshwaters. This may have implications for water quality monitoring.  相似文献   

波段选择协同表达高光谱异常探测算法     

朱德辉  杜博  张良培 《遥感学报》2020,24(4):427-438

高光谱遥感影像具有光谱分辨率极高的特点,承载了大量可区分不同类型地物的诊断性光谱信息以及区分亚类相似地物之间细微差别的光谱信息,在目标探测领域具有独特的优势。与此同时,高光谱遥感影像也带来了数据维数高、邻近波段之间存在大量冗余信息的问题,高维度的数据结构往往使得高光谱影像异常目标类和背景类之间的可分性降低。为了缓解上述问题,本文提出了一种基于波段选择的协同表达高光谱异常探测算法。首先,使用最优聚类框架对高光谱波段进行选择,获得一组波段子集来表示原有的全部波段,使得高光谱影像异常目标类与背景类之间的可分性增强。然后使用协同表达对影像上的像元进行重建,由于异常目标类和背景类之间的可分性增强,对异常目标像元进行协同表达时将会得到更大的残差,异常目标像元的输出值增大,可以更好地实现异常目标和背景类的分离。本文使用了3组高光谱影像数据进行异常目标探测实验,实验结果表明,该方法与其他现有高光谱异常目标探测算法对比,曲线下面积AUC(Area Under Curve)值更高,可以更好地实现异常目标与背景分离,能够更有效地对高光谱影像进行异常目标探测。  相似文献   

Physico-chemical,bacteriological and health hazard effect analysis of the water in Taladanda Canal,Paradip area,Odisha, India          下载免费PDF全文

Rabiranjan Prusty  Trinath Biswal 《地下水科学与工程》2020,8(4):338-348

The physico-chemical and bacteriological parameters of the water in Taladanda canal and associated water-borne diseases,from which the dwellers have suffered,were studied,by using statistical method. Overuse and the addition of the wastes with sources from urbane industrial sectors,as well as the decrease in water level have caused the canal water quality declined drastically and subsequently led to extensive eutrophication and bacterial contamination. According to the water sample analytical results,the water is lightly acidic with the pH value of 4.5~6.7. The measured indexes,such as total dissolved solid (TDS),electrical conductivity (EC),total suspended solid (TSS),Mn,Zn,Al,Fe,Cu,Cr,and Hg etc,mostly have very high concentrations which are higher than permissible limit,indicating that the canal water is completely unsuitable for human consumption. Furthermore,the biological analysis shows that the total coliform (TC) is in the range of 45.9~30.2 in per 100 mL water in April,30.5~25.3/100 mL in July and 52.9~35.4/100 mL in December,respectively. Similarly,fecal coliform (FC) ranges from 12.8 to 10.1,10.5~7.5 and 13.1~6.4 per 100 mL water in the months of April,July and December respectively. As a result,people who use the water have suffered from different water-borne diseases. On the basis of disease data derived from hospital observations in a period of three years,there had been 4 284 people affected by different water-borne diseases from 2016 to 2018.  相似文献   

适宜浓度的维生素E促进半滑舌鳎生长激素基因的表达     

王蔚芳  向玲  王琳  黄滨  李会涛 《海洋科学》2020,44(2):113-119

本实验旨在探究维生素E对半滑舌鳎垂体组织中生长激素基因表达的影响。作者在每千克等氮等能的基础饲料中分别添加0、400和1 600mg的DL-α-生育酚乙酸酯(维生素E)投喂半滑舌鳎(Cynoglossus semilaevis)成鱼(464±2.6) g,进行为期8周的养殖实验;另外,在L-15培养基中添加0、18和54μmol/L的维生素E,对半滑舌鳎成鱼(464±2.6) g的垂体细胞进行为期3 d的体外原代培养实验。分别取垂体组织和原代细胞,通过荧光实时定量PCR分析其gh mRNA的相对表达量。实验结果表明:垂体组织中gh mRNA的相对表达量随着饲料中维生素E含量的增加而呈现先升高后下降的变化趋势,在400 mg/kg组时显著高于其他各组(P0.05);随着细胞培养液中维生素E浓度的升高, gh mRNA的相对表达量显著增加(P0.05)。由此可见,适宜浓度的维生素E能够促进半滑舌鳎垂体组织中生长激素基因的表达。  相似文献   

Evaporation modelling by heuristic regression approaches using only temperature data   总被引：1，自引：1，他引：0  

Ozgur Kisi  Salim Heddam 《水文科学杂志》2019,64(6):653-672

Accurate estimation of pan evaporation (E_pan) is very important in water resources management, irrigation scheduling and water budget of lakes. This study investigates the accuracy of two heuristic regression approaches, multivariate adaptive regression splines (MARS) and M5 model tree (M5Tree) in estimating pan evaporation using only temperature data as input. Monthly minimum temperature, maximum temperature and E_pan data from three Turkish stations were used, with month number (periodicity information) added as input to see its effect on estimation accuracy. The models were compared with the calibrated Hargreaves-Samani (CHS), Stephens-Stewart (SS) and multiple linear regression methods. Three different train-test splitting strategies (50%–50%, 60%–40% and 75%–25%) were employed for better evaluation of the applied methods. The results show that the MARS method generally estimated monthly E_pan with higher accuracy compared to the M5Tree, CHS and SS methods. When extraterrestrial radiation, calculated from Julian date and latitude information, was used as input to the SS instead of solar radiation, satisfactory estimates were obtained. A positive effect on model accuracy was observed when involving periodicity information in inputs and increasing training data length.  相似文献   

Polynomial chaos expansion and response surface method for nonlinear modelling of reference evapotranspiration     

Behrooz Keshtegar  Ozgur Kisi  Mohammad Zounemat-Kermani 《水文科学杂志》2019,64(6):720-730

The feasibility of polynomial chaos expansion (PCE) and response surface method (RSM) models is investigated for modelling reference evapotranspiration (ET₀). The modelling results of the proposed models are validated against the M5 model tree and multi-layer perceptron neural network (MLPNN) methods. Two meteorological stations, Isparta and Antalya, in the Mediterranean region of Turkey, are inspected. Various input combinations of daily air temperature, solar radiation, wind speed and relative humidity are constructed as input attributes for the ET₀. Generally, the modelling accuracy is increased by increasing the number of inputs. Including wind speed in the model inputs considerably increases their accuracy in modelling ET₀. Mean absolute error (MAE), root mean square error (RMSE), agreement index (d) and Nash-Sutcliffe efficiency (NSE) are used as comparison criteria. The PCE is the most accurate model in estimating daily ET₀, giving the lowest MAE (0.036 and 0.037 mm) and RMSE (0.047 and 0.050 mm) and the highest d (0.9998 and 0.9999) and NSE (0.9992 and 0.9996) with the four-input PCE models for Isparta and Antalya, respectively.  相似文献   

CTS-1E、CMG-3ESPC-120型地震计工作参数对比分析     

段绍鑫  乌尼尔  李晓东  张森  张小飞 《地震地磁观测与研究》2019,40(4):120-124

CTS-1E型、CMG-3ESPC-120型地震计安装架设在库尔勒地震台小泉沟观测点同一台基上，均使用EDAS-24GN型数据采集器进行实时数据采集，对比分析观测数据波形特征、地动噪声功率谱及动态范围等，明确2套地震计在实际观测中的性能差异，以便为地震监测数据分析及相关研究提供参考。  相似文献   

基于CMIP5模式鄱阳湖流域未来参考作物蒸散量预估   总被引：3，自引：0，他引：3  

刘子豪  陆建忠  黄建武  陈晓玲  张玲  盛颖东 《湖泊科学》2019,31(6):1685-1697

预测未来气候情境下鄱阳湖流域参考作物蒸散量(Reference crop Evapotranspiration,ET0)的时空分布可为流域水资源的优化管理,为科学应对气候变化对农业生产的影响提供基础数据支撑.利用鄱阳湖流域14个气象站点1961-2014年逐日气象数据,采用Penman-Monteith公式计算出历史ET0;基于同期美国环境中心(NCEP)再分析数据及2006-2100年CMIP5中CNRM-CM5模式在RCP4. 5和RCP8. 5情景下的预测数据,经统计降尺度模型(statistical downscaling model,SDSM)模拟和偏差校正,预测流域未来ET0;通过Mann-Kendall检验、普通克里金插值和空间自相关法分析了流域1961-2100年ET0的时空演变特征.结果表明:NCEP再分析资料与流域ET0建立的逐步回归降尺度模型模拟效果较好,CNRMCM5模式降尺度模拟结果经偏差校正后,精度明显提高,适宜流域未来ET0的预估.鄱阳湖流域在基准期1961-2010年ET0整体上呈减小趋势,空间分布上呈南北高、中间低的特点,表现出明显的空间差异性.RCP4.5、RCP8.5情景下未来3个时期鄱阳湖流域ET0较基准期均呈不同程度的增加趋势,其空间分布整体表现为东高西低、局地略有突出;无论是在基准期或是未来情景下的3个时期,ET0均具有较强的空间自相关性.在RCP8.5情景下,鄱阳湖1961-2100年干旱指数呈现出较为明显的上升趋势,流域的干旱状况随时间加剧,2011-2100年间流域绝大部分地区由湿润区转为半湿润区,干旱指数自南向北递减,赣江流域将是鄱阳湖流域未来干旱风险的重点防范区.  相似文献