Winkler's method overestimates dissolved oxygen in seawater: Iodate interference and its oceanographic implications     

George T.F. Wong  Kuo-Yuan Li 《Marine Chemistry》2009,115(1-2):86-91

Dissolved oxygen in seawater has been determined by using the Winkler's reaction scheme for decades. An interference in this reaction scheme that has been heretofore overlooked is the presence of naturally occurring iodate in seawater. Each mole of iodate can result in an apparent presence of 1.5 mol of dissolved oxygen. At the concentrations of iodate in the surface and deep open ocean, it can lead to an overestimation of 0.52 ± 0.15 and 0.63 ± 0.05 μmol kg^− 1 of oxygen in these waters respectively. In coastal and inshore waters, the effect is less predictable as the concentration of iodate is more variable. The solubility of oxygen in seawater was likely overestimated in data sources that were based on the Winkler's reaction scheme for the determination of oxygen. The solubility equation of García and Gordon [Garcia H.E., Gordon, L.I., 1992. Oxygen solubility in seawater: Better fitting equations. Limnol. Oceanogr. 37, 1307–1312] derived from the results of Benson and Krause [Benson, F.B., Krause, D. Jr., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnol. Oceanogr. 29, 620–632] is free from this source of error and is recommended for general use. By neglecting the presence of iodate, the average global super-saturation of oxygen in the surface oceans and the corresponding efflux of oxygen to the atmosphere both have been overestimated by about 8%. Regionally, in areas where the degree of super-saturation or under-saturation of oxygen in the surface water is small, such as in the tropical oceans, the net air–sea exchange flux can be grossly under- or overestimated. Even the estimated direction of the exchange can be reversed. Furthermore, the presence of iodate can lead to an overestimation of the saturation anomaly of oxygen in the upper ocean attributed to biological production by 0.23 ± 0.07%. AOU may have been underestimated by 0.52 ± 0.15 and 0.63 ± 0.05 μmol kg^− 1 in the surface mixed layer and deep water, while preformed phosphate and preformed nitrate may have been overestimated by 0.004 ± 0.001 and 0.06 ± 0.02 μmol kg^− 1 in the surface mixed layer, and 0.005 ± 0.0004 and 0.073 ± 0.006 μmol kg^− 1 in the deep water. These are small but not negligible corrections, especially in areas where the values of these parameters are small. At the increasing level of sophistication in the interpretation of oxygen data, this source of error should now be taken into account. Nevertheless, in order to avoid confusion, an internationally accepted standard needs to be adopted before these corrections can be applied.  相似文献   

Economic gains of liberalising access to fishing quotas within the European Union     

Jesper L. Andersen  Max Nielsen  Erik Lindebo 《Marine Policy》2009

This paper analyses the extent to which specialisation gains can be achieved by liberalising access to fishing quotas within the European Union (EU). Fishing quotas are today exchanged between EU member states at a rate of 4% of total turnover in EU fisheries. Germany, Belgium, Denmark and the Netherlands are the most active. Only one fourth of these exchanges are permanent. With the management systems in EU fisheries differing among countries, comparative advantages in fisheries exist in member states with the best management practices. Hence, although positive but small specialisation gains exist in EU fisheries today, these gains might potentially be increased by liberalising access to fishing quotas and allowing transferability of quotas between individuals from different countries on a permanent basis. Increasing the gains might, however, affect relative stability.  相似文献   

Characteristics of water exchange in the Luzon Strait during September 2006   总被引：7，自引：1，他引：6  

周慧  南峰  侍茂崇  周良明  郭佩芳 《中国海洋湖沼学报》2009,27(3):650-657

The Luzon Strait is the only deep channel that connects the South China Sea(SCS) with the Pacific.The transport through the Luzon Strait is an important process influencing the circulation,heat and water budgets of the SCS.Early observations have suggested that water enters the SCS in winter but water inflow or outflow in summer is quite controversial.On the basis of hydrographic measurements from CTD along 120° E in the Luzon Strait during the period from September 18 to 20 in 2006,the characteristics of t...  相似文献   

EFFECTS OF COMPOSITION AND STRUCTURE OF ALGINATES ON ADSORPTION OF DIVALENT METALS     

郑乃余  张燕霞  范晓  韩丽君 《中国海洋湖沼学报》1994,(1)

Results of a series of experiments(on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of different composition and block structure) conducted in this systematic study of the effects of the composition and structure of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of the M/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu~(2+) ion decrease with the increase of the G-block or the average length of the G-block ((?)_G) and the total adsorption capacity of alginic acid is found to vary in the same order as the F_(MM)(diad frequency) in alginate in  相似文献   

A Sensitivity Study of Arctic Ice-Ocean Heat Exchange to the Three-Equation Boundary Condition Parametrization in CICE6     

Lei YU  Jiping LIU  Yongqi GAO  Qi SHU 《大气科学进展》2022,39(9):1398-1416

In this study, we perform a stand-alone sensitivity study using the Los Alamos Sea ice model version 6(CICE6) to investigate the model sensitivity to two Ice-Ocean(IO) boundary condition approaches. One is the two-equation approach that treats the freezing temperature as a function of the ocean mixed layer(ML) salinity, using two equations to parametrize the IO heat exchanges. Another approach uses the salinity of the IO interface to define the actual freezing temperature, so an equation describ...  相似文献   

城市GIS数据多级共享交换平台系统     

张海涛  张书亮  姜杰  顾燕 《地球信息科学学报》2007,9(1):116-122

针对目前城市众多管理部门对城市GIS数据共享交换平台不同层次的共享需求,在分析文件级、数据平台级、系统功能级以及Web服务级四种共享交换模式特点的基础上,本文采用业务流技术设计了一种集成多级共享交换模式的数据模型。结合无锡市地理信息共享交换平台项目的建设,给出了模型在城市GIS数据交换平台系统中的具体应用过程,以期对其他城市同类系统的建设提供一定的参考价值。  相似文献   

防灾减灾系统灾情信息集成技术研究   总被引：1，自引：0，他引：1  

石丽红  栗斌  张清浦 《地理信息世界》2007,5(1):47-51

全球各类自然灾害的频繁发生,给各国人民的生活和生产带来了严重灾难和重大损失。通过建立防灾减灾系统,有效减少灾害带来的损失,越来越受到各国政府及灾害主管部门的重视。本文结合地理信息系统的地理编码技术、大型关系数据库技术、动态数据交换技术,详细阐述了应用于政府部门的防灾减灾系统中灾情信息的集成方法及具体实现。  相似文献   

从第34届国际水文地质大会看水文地质学发展趋势(代序)   总被引：3，自引：0，他引：3  

石建省 《地球学报》2007,28(6):509-520

第34届国际水文地质大会于2006年10月9-13日在北京召开,来自56个国家和地区的567名代表参加了会议.这次会议的大会学术报告和九个分专题会场交流集中反映出当前国际水文地质学科发展的若干热点领域和重要发展方向,与会各国专家对地下水水质安全与污染修复、地下水补给机制和生态功能、地下水勘察评价的技术发展等领域给与了更多关注,反映这些领域是当前地下水研究的热点,说明水文地质学科的发展明显转向解决社会广泛关注的现实的应用性问题,包括维持生态系统、维护水质安全、防止地质灾害等方面,特别是这些问题与城市发展、农村脱贫、矿业基地、重大工程建设的结合.同位素、数值模拟和其他地下水勘察、评价、开发技术的快速发展,为更好地认识、利用和管理含水层系统,服务于上述应用性目标提供了保障.IAH将今后工作的重点放在亚洲地区,对跨边界含水层管理等问题十分关注.媒体的集中报道反映出水文地质工作与社会的结合已经相当紧密.  相似文献   

Spatial patterns of groundwater‐lake exchange – implications for acid neutralization processes in an acid mine lake     

Christiane Neumann  Julia Beer  Christian Blodau  Stefan Peiffer  Jan H. Fleckenstein 《水文研究》2013,27(22):3240-3253

Exchange of groundwater and lake water with typically quite different chemical composition is an important driver for biogeochemical processes at the groundwater‐lake interface, which can affect the water quality of lakes. This is of particular relevance in mine lakes where anoxic and slightly acidic groundwater mixes with oxic and acidic lake water (pH < 3). To identify links between groundwater‐lake exchange rates and acid neutralization processes in the sediments, exchange rates were quantified and related to pore‐water pH, sulfate and iron concentrations as well as sulfate reduction rates within the sediment. Seepage rates measured with seepage meters (?2.5 to 5.8 L m^‐2 d^‐1) were in reasonable agreement with rates inverted from modeled chloride profiles (?1.8 to 8.1 L m^‐2 d^‐1). Large‐scale exchange patterns were defined by the (hydro)geologic setting but superimposed by smaller scale variations caused by variability in sediment texture. Sites characterized by groundwater upwelling (flow into the lake) and sites where flow alternated between upwelling and downwelling were identified. Observed chloride profiles at the alternating sites reflected the transient flow regime. Seepage direction, as well as seepage rate, were found to influence pH, sulfate and iron profiles and the associated sulfate reduction rates. Under alternating conditions proton‐consuming processes, for example, sulfate reduction, were slowed. In the uppermost layer of the sediment (max. 5 cm), sulfate reduction rates were significantly higher at upwelling (>330 nmol g^‐1 d^‐1) compared to alternating sites (<220 nmol g^‐1 d^‐1). Although differences in sulfate reduction rates could not be explained solely by different flux rates, they were clearly related to the prevailing groundwater‐lake exchange patterns and the associated pH conditions. Our findings strongly suggest that groundwater‐lake exchange has significant effects on the biogeochemical processes that are coupled to sulfate reduction such as acidity retention and precipitation of iron sulfides. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

ICP—AES法分析辉锑矿   总被引：1，自引：0，他引：1  

曾惠芳 《岩矿测试》1990,9(2):93-99

本文针对辉锑矿成分复杂、主元素Sb易水解、部分元素易挥发,酸不溶元素的存在以及元素之间的干扰等问题,拟定了酸溶和碱熔分解试样的分析流程。在酸溶系统中结合TBP萃淋树脂和巯基棉分离富集分组,ICP-AES法测定Fe、Ca、Mg、Cu、Mn、Pb、Zn、Co、Ni、Au、Ag、In、Tl、Cd、Bi、Ga、Mo、Se、Te、As等20个元素。碱熔系统不分离主元素,用校正因素校正元素间光谱干扰并采用内标法ICP-AES测定Al、Ti、V、Ba、Sr、Sn、Sc、Cr、Be、Si和Sb等11个元素。试样验证表明,方法可行。  相似文献