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51.
E. V. Yakushev E. L. Vinogradova A. V. Dubinin A. V. Kostyleva N. M. Men’shikova S. V. Pakhomova 《Oceanology》2012,52(1):122-129
The accuracy and detection limit of the oxygen technique is an actual problem in studying the processes that occur in the
redox zone. The formal accuracy of the Winkler technique is 1 μM (0.02 mL L−1) and its detection limit is about 3.0 μM (0.06 mL L−1). These values are significantly higher than the similar characteristics (in molar concentrations) for such parameters as
the hydrogen sulphide, nitrates, manganese, and others. In this work, we describe some recommendations for increasing the
accuracy of the Winkler technique. The results of the application of these recommendations for the suboxic zone of the Black
Sea are presented. During the 100th cruise of the R/V Professor Shtokman, argon-filled balloons were attached to the upper valves of Niskin bottles during the sampling, which allowed protecting
the samples from contamination with atmospheric oxygen. The titration was performed with an automatic Metrohm Titrino burette
with potentiometric end point detection. That allowed us to significantly increase the accuracy and decrease the detection
limit compared with the visual techniques. The oxidized forms of metals present in the sea water (Mn(IV), Mn(III); Fe(III))
were measured, which allowed us to correct the Winkler technique calculations for the oxidizers. The studies performed during
the 100th cruise of the R/V Professor Shtokman confirmed the absence of a layer of the coexistence of oxygen and hydrogen sulphide. 相似文献
52.
Beatriz González-Fernández Mónica Meléndez-Asensio Eduardo Menéndez-Casares 《Environmental Earth Sciences》2009,59(4):913-928
Chemical and isotopic analyses of groundwater from the carbonated Jurassic aquifers in the Gijón-Villaviciosa basin (Asturias,
northern Spain) were carried out. Nine springs were sampled to determine major cations and anions, as well as the stable isotopes
of the water molecule (δ2H and δ18O) and sulphate (δ34S) values. Also, δ34S values from gypsum coming both from Triassic rocks and bottom of Jurassic sequence were also determined. The results obtained
were used to classify the waters with a genetic criteria in three groups: (1) waters with a high gypsum influence, with sulphate
coming from Jurassic gypsum, (2) waters without gypsum influence, where sulphate source could be atmospheric deposition from
industrial processes and marine aerosol, and (3) waters with some gypsum influence, in which sulphate origin could be a combination
of different sources. In relation to recharge, δ2H and δ18O values were close to those of Global Meteoric Water Line and fit a local line that suggests a meteoric origin. The estimated
elevations for spring recharge are in agreement with those obtained from hydrogeological maps. 相似文献
53.
秦岭东段主要类型金红石矿床的稀土元素地球化学特征 总被引:1,自引:1,他引:1
秦岭东段主要原生金红石矿床均受不同程度的变质作用形成。通过对该区四种主要金红石矿床稀土元素地球化学特征的分析及对含矿原岩的恢复,认为本区不同类型金红石矿床的∑REE、LREE/HREE、δEu值等特征有很大差别,并显示出了本区金红石矿床成因的多样性和复杂性;稀土元素与Ti的富集关系的研究结果表明:任何一种类型矿床中,稀土越富集,轻、重稀土分异程度越高,δEu值越大,越有利于Ti的富集。 相似文献
54.
55.
大巴山地区早古生代发育下寒武统水井沱组(巴山组—鲁家坪组)和上奥陶统五峰组—下志留统龙马溪组2套黑色岩系。沉积学研究表明,2套黑色岩系均发育于扬子北缘被动大陆边缘盆地之上,早期快速海侵,沉积环境以深水陆棚为主,晚期随着海平面下降逐渐变为浅水陆棚沉积,局部发育滩礁沉积。早寒武世和晚奥陶世—早志留世,研究区均处于被动大陆边缘盆地,基底不平整,陆架边缘呈现多个小岛阻隔的古地理格局,但两者的形成机制却完全不同:早寒武世的构造格局沿袭了陡山沱期的地堑和地垒分布格局,地垒处表现为局部隆起或水下潜隆;晚奥陶世—早志留世的构造格局则与扬子板块向华北板块俯冲有关,是在扬子北缘被动大陆边缘基础上发育起来的前陆隆起。这种受限的滞留海域有利于形成厚度大、有机碳含量高(2%~6%)、脆性矿物含量高(40%~65%)的富有机质页岩,虽然其是页岩气勘探的有利目标层系,但仍需加强构造保存条件的研究。 相似文献
56.
57.
峪耳崖金矿床位于华北板块北缘中段,是冀东地区金厂峪[CD1]峪耳崖矿集区内赋存于花岗岩体及其与长城系围岩接触带内的大型金矿床。通过系统的成矿地质特征、流体包裹体、氢氧同位素、硫铅同位素和稀土-微量元素研究,结果表明:成矿温度为中高温热液环境,成矿流体为低盐度,成矿物质来源具有深源和幔源特征,金成矿作用过程具有排斥稀土元素的作用,Bi可作为富金矿体的指示元素。而峪耳崖金矿产于岩浆岩发育区和金厂峪金矿赋存于老变质岩区的表观成矿地质特征差异性、牛心山金矿“一墙之隔”的南北雷同性(南与金厂峪类同,北与峪耳崖类同)和它们成矿物质来源的同源性,则表明具体成矿就位地质环境的特定性决定了金矿床表观地质特征的特异性和复杂性。 相似文献
58.
The Taklimakan Desert, the world's second largest desert, plays an important role in regional climate change. Previous studies on its spatial temperature features suffered from sparse conventional detection data, but the Atmospheric Infrared Sounder(AIRS) provides excellent temperature retrievals with high spatiotemporal resolution. Validation of AIRS temperature retrievals over desert regions with high land-surface emissivity, the key contributor to inversion error, is essential before using these data in regional weather/climate modeling. This paper examines the correlation coefficients, root mean square error(RMSE) and mean BIAS between AIRS-retrieved atmospheric temperature data and radiosonde observations(RAOBs) in the Taklimakan Desert hinterland and oases in the morning and at dusk. Firstly, the AIRS retrievals are consistent with RAOBs and are more consistent in the morning than at dusk. The consistency is better over a small-scale desert oasis than over a large-scale oasis in the morning and exhibits the opposite trend at dusk. The correlation coefficient over the hinterland is high in the morning but negative at dusk due to high desert-surface emissivity. Second, the RMSEs, which are all smaller than 3 K, are generally higher over desert sites than over oasis sites and slightly lower over a small-scale oasis than over a large-scale oasis in the morning. At dusk, the RMSEs are higher over desert sites than over oases and slightly higher over a small-scale oasis than over a large-scale oasis. Furthermore, the RMSEs are generally higher in the morning than at dusk over a large-scale oasis and lower in the morning than at dusk over a small-scale oasis. Third, the absolute mean BIAS values are mostly lower than 1 K. In the morning, relative to RAOB temperatures, the retrieval temperatures are higher over desert sites but lower over oasis sites. At dusk, the retrieval temperatures are lower than RAOB temperatures over both desert and oasis sites. The retrieval temperatures are higher than RAOB temperatures over desert sites in the morning but slightly lower at dusk. Most absolute mean BIAS values are higher in the morning than at dusk over both oasis and desert sites. Finally, the consistency between the AIRS and RAOB temperature data is high from 700 hPa to 100 hPa in the morning and from 700 hPa to 300 hPa at dusk. The difference between the AIRS and RAOB temperature data is generally higher in the morning than that at dusk. The RMSE differences between the AIRS and RAOB data are slightly lower in the morning than at dusk and are lower in the middle layers between 700 hPa and 150 hPa than in the layers above 150 hPa during both the morning and night. The BIAS is lower in the morning than at dusk below 300 hPa but higher in the upper layers. Moreover, the BIAS value is positive in the middle layers between 500 hPa and 150 hPa and negative at other levels at both times. Generally, the AIRS retrieval temperatures are reliable and can be used in further studies in the Taklimakan Desert. 相似文献
59.
根据1500年以来的地震资料分析,江苏-南黄海地区M≥5中强震具有显著的干支60周期性特征,南黄海海域M≥6强震具有良好的可公度性,并对其基本结构和预测功能进行了研究。未来几年该区依然存在5 ̄6级地震的危险性,第二活跃幕可能将持续到2009年前后。 相似文献
60.
胶州湾浮游植物分子遗传多样性初步研究 总被引:1,自引:0,他引:1
用聚合酶链式反应扩增海洋浮游植物总体的核酮糖 1 ,5 -二磷酸羧化 /氧化酶大亚基基因(rbc L)片段 ,建立该基因变异类型文库 ,并随机测定了 38个 rbc L大亚基基因片段序列 ,初步分析了海洋浮游植物分子遗传多样性。将≥ 97%的氨基酸序列相似性定义为种内变异 ,38个片段分别代表1 3个不同的物种 ,或称为不同的操作分类单元。与数据库序列比较发现 ,PPJZ0 1 ,PPJZ1 1和 PPJZ2 0可能是已报道的 rbc L基因序列代表的物种 ,其它克隆在数据库中没有对应的近缘物种序列存在。系统学分析表明分离的克隆分别属于隐藻门、硅藻门、绿藻门和 streptophyta等的浮游植物 ,极少数克隆来源于异鞭毛藻类、定鞭藻纲和原细菌。根据各操作分类单元克隆数计算得胶州湾浮游植物分子遗传多样性指数为 1 .97。研究结果为利用分子生物学方法剖分海洋浮游植物群落结构、研究海洋浮游植物动力学积累了基础数据 相似文献