Electrochemical behavior of Al—basic sacrificial anode at estuary     

Zhang Jing-lei  Hou Bao-rong  Li Hong-ling  Yang Fang-ying  Xie Xiao-bo 《中国海洋湖沼学报》1996,14(3):272-275

The Al—basic sacrificial anode is widely used to protect steel construction from corrosion in seawater, but is not suitable for protecting steel in freshwater. In the estuary area, seawater and freshwater mix and different seawater salinity can be formed in different mixing sites between freshwater and seawater. Based on the requirements of the Shengli Petroleum Administrative Bureau of China, the effect of seawater salinity on electrochemical properties of Al—basic anode was studied under laboratory conditions by the method given in National Standard GB 4948-85 (China Starndard Bureau, 1985). No obvious effect was found when seawater salinity was 30 to 10, but obvious effect on anodic open circuit potential, closed circuit potential and current efficiency was found when seawater salinity was 5. These values are lower than those given in the National Standard. Contribution No. 2681 from the Institute of Oceanology, Chinese Academy of Sciences. This study is a major project (Ky85-11-5) and a key project (A14920416) of the Chinese Academy of Sciences, and also received support from the Shengli Oil Field.  相似文献   

PRIMARY FISH SURVEY IK THE HUANGHE RIVER ESTUARY     

杨纪明  王存信 《中国海洋湖沼学报》1993,(4)

The survey in the, Huanghe River estuary indicated that the 85 fish species found there comprised three faunal elements: warm-water species (29.4%), warm-temperate species (55.3%) and cpld-temperate species. (15.3%). The seasonal changes of fish species, density and bipmass are obvious. The total biomass is highest (7699t) in August and lowest(489 t) in January. Setipinna taty has mean density of 9278 indiv/km2, and is the most important species constituting 25.5% of the total weight of fish caught. Trichiurus haumela was a dominant species in the 1950s, but no one was caught in this survey. There were obvious changes of the dominant fish species during the recent three decades. The demersal fish biomass has dropped greatly to only 1/10 in over 50 years since 1930.  相似文献   

对黄河下游第四系覆盖区国土资源大调查内容的思索          下载免费PDF全文

张尚坤  张增奇  王敏  王克光  杜圣贤 《山东国土资源》2001,17(6):22-26

对黄河下游第四系覆盖区的综合地质调查是山东省国土资源大调查的重点.根据该地区的地质情况,其调查内容主要包括土地资源调查、基础地质调查、农业地质调查、农业地质区划、农用矿产调查、水工环地质调查、旅游地质及城市地质调查.在调查过程中要力争解决国土资源调查评价与利用新技术和新方法过程中面临的新问题,建立国土资源调查与评价的综合体系,为黄河下游第四系覆盖区工农业生产提供科学依据.  相似文献   

DETERMINATION OF SEDIMENTARY RATE IN ESTUARY AND COAST BY ^228 Th TECHNIQUE     

朱校斌 施伟康建海  秦晓光康兴伦  顾德隆张经 《中国海洋湖沼学报》2001,19(4):368-374

Analysis of ^232Th, ^230Th , and ^228Th in sediments showed that there was an excess of ^228Th over that supported by the parents ^282Th or ^228Ra in sediments in many regions. This excess ^228Th with a half-life of 1.91 years can be used for dating purpose over a time period of the order of a decade, so average sedimentary rates in the Yalujiang River Estuary, and in the Huanghe River Estuazy and its adjacent Laizhou Bay can be obtained from decreases in the excess ^228Th activity as a function of depth in sediment.  相似文献   

GEOCHEMICAL CHARACTERISTICS OF SEDIMENTS AND ANALYSIS OF THE CHANGJIANG ESTUARY ENVIRONMENT     

田汝成  陈吉余  刘苍字  王效京 《中国海洋湖沼学报》1992,10(1):1-8

Analysis of material from three 55- cm long cores collected with box corer m summer of 1988 in the Changjiang Estuary region yielded data on the sedimentation rate, granulometric composition and contents of carbonates, organic matter, Al, Fe, Mn, Zn, Cu and Pb there. Subsequent study of the data led to the conclusion that there is no obvious pollution in the region based on the absolute value of the content of heavy metals, but the region is in potential danger of being polluted as seen by the obvious increase of sedimentation flux of heavy metals to and the enrichment of them on the surface sediment during the last several years, e.g. Pb increased by 10-20μg/g, Zn by about 30μg/g, Cu by 5-10μg/g and Mn by 150μg/g.A ferromanganese redox interface was found at about 40 cm depth of sediments where Fe and Mn and associated trace metals are enriched. The trace metals such as Zn, Cu have (but Pb does not) the same source, forms, displacement mechanism and geochemical behaviours as those of Fe and Mn in t  相似文献   

Arsenic,barium, germanium,tin, dimethylsulfide and nutrient biogeochemistry in Charlotte Harbor,Florida, a phosphorus-enriched estuary     

P.N. Froelich  L.W. Kaul  J.T. Byrd  M.O. Andreae  K.K. Roe 《Estuarine, Coastal and Shelf Science》1985,20(3):239-264

Concentrations of dissolved nutrients (NO₃, PO₄, Si), germanium species, arsenic species, tin, barium, dimethylsulfide and related parameters were measured along the salinity gradient in Charlotte Harbor. Phosphate enrichment from the phosphate industry on the Peace River promotes a productive diatom bloom near the river mouth where NO₃ and Si are completely consumed. Inorganic germanium is completely depleted in this bloom by uptake into biogenic opal. The $\text{Ge}\text{Si}$ ratio taken up by diatoms is about 0·7 × 10^?6, the same as that provided by the river flux, confirming that siliceous organisms incorporate germanium as an accidental trace replacement for silica. Monomethylgermanium and dimethylgermanium concentrations are undetectable in the Peace River, and increase linearly with increasing salinity to the seawater end of the bay, suggesting that these organogermanium species behave conservatively in estuaries, and are neither produced nor consumed during estuarine biogenic opal formation or dissolution. Inorganic arsenic displays slight removal in the bloom. Monomethylarsenic is produced both in the bloom and in mid-estuary, while dimethylarsenic is conservative in the bloom but produced in mid-estuary. The total production of methylarsenicals within the bay approximately balances the removal of inorganic arsenic, suggesting that most biological arsenic uptake in the estuary is biomethylated and released to the water column. Dimethylsulfide increases with increasing salinity in the estuary and shows evidence of removal, probably both by degassing and by microbial consumption. An input of DMS is observed in the central estuary. The behavior of total dissolvable tin shows no biological activity in the bloom or in mid-estuary, but does display a low-salinity input signal that parallels dissolved organic material, perhaps suggesting an association between tin and DOM. Barium displays dramatic input behavior at mid-salinities, probably due to slow release from clays deposited in the harbor after catastrophic phosphate slime spills into the Peace River.  相似文献   

福建洛阳江口红树林湿地及其周边地区景观变化研究   总被引：2，自引：0，他引：2  

李伟  崔丽娟  张曼胤  王义飞 《湿地科学》2009,7(1)

利用"3S"技术,对福建洛阳江口红树林湿地及周边地区1993年、2001年、2003年和2006年遥感影像进行了动态分析.将研究区的景观类型划分为红树林、米草(Spartina)地、滩涂、水域、建设及交通用地、其他林地与农田7类;分析各类型景观格局特征和动态变化以及各景观类型间的转化.结果表明,4个时期的红树林面积发生明显变化,与1993年相比,2006年红树林的面积增加了5倍,达到145.08 hm2;红树林的空间分布范围也在不断向南延伸,红树林空间质心变化由早期向西北偏移变为后期向东南偏移.4个时期中,研究区红树林的平均斑块面积在2001年最小(0.34 hm2),而斑块数(58)、破碎度(0.000 291)、分离度(223.15)、斑块形状指数(20.67)、分维数(1.50)都在2001年达到最大,红树林在2001年破碎化现象最明显,分布零散,斑块形状最复杂.2001年,研究区其他6种景观类型的连续性和整体性较差,这与研究区附近城乡建设和经济发展有关.滩涂与其他林地的动态度在2003～2006年间最大;红树林、米草地、建设及交通用地以及农田的动态度在2001～2003年间最大,这主要与城乡建设以及红树林湿地恢复和外来入侵物种防治工作有关.在其他林地、建设及交通用地和农田的面积转化中,建设及交通用地面积在1993～2006年间增加了1 526.17 hm2.  相似文献   

福建闽江河口湿地观鸟旅游发展分析   总被引：1，自引：0，他引：1  

郑丽娟 《湿地科学与管理》2009,5(3):25-28

闽江河口湿地是福建省最大的湿地,为了更好地保护和开发湿地,发展观鸟旅游具有非常重要的意义。纵现国内外观鸟旅游的发展,闽江河口湿地的观鸟旅游必须在保护鸟类及生存环境的基础上,加强整体规划和管理;加大对湿地和鸟类知识的宣传和教育,培育潜在观鸟旅游市场;丰富观鸟旅游产品的形式,鼓励社区参与,共同致力于湿地的保护与开发。  相似文献   

Morphological evolution of the Dee Estuary, Eastern Irish Sea, UK: A tidal asymmetry approach     

Rowena D. Moore  Judith Wolf  Alejandro J. Souza  Stephen S. Flint 《Geomorphology》2009,103(4):588-596

Asymmetry in the tide (unequal ebb and flood duration) is a dominant factor in causing residual sediment transport and morphological changes in estuaries. The evolution of estuarine morphology is a process of dynamic equilibrium in the short-term, while these features are ephemeral in the long-term. In this study we investigate the spatial distribution of tidal distortion and asymmetry in the Dee estuary, UK, by 3-dimensional numerical modelling methods. High resolution LIDAR surveys are used to underpin and explain our numerical modelling results in terms of basin hypsometry and areas of recent erosion and deposition. Harmonic analysis of the numerical modelling results showed that the shallower intertidal areas (sand and mud banks) were the most tidally asymmetric, showing flood dominance. The main navigation channels showed some ebb dominance but the tides here were relatively undistorted. This overall flood dominance is likely to induce net sediment import to the Dee, which explains known historical morphological changes (large scale accretion over the last two centuries) and also recent morphological changes as seen from the LIDAR surveys (which show predominantly net accretion between 2003 and 2006). Hypsometrical analysis suggests the Dee may be approaching equilibrium, and that the flood dominance and sedimentation rate may therefore decrease in the future. In an infilling estuary, an increase in the area and elevation of tidal flats can eventually shift an estuary towards ebb dominance, as shown by previous research and by ‘idealised estuary’ modelling results presented in this study. The large tidal amplitude to hydraulic depth ratio of the Dee, however, suggests that the tidal flats would have to be very extensive indeed for this to occur.  相似文献   

Early Eocene estuary at Strahan,Tasmania     

M. S. Pole 《Australian Journal of Earth Sciences》2013,60(6):979-985

Evidence from sedimentology is combined with that of palynology and macropalaeobotany to arrive at a general reconstruction of the Early Eocene environment in Macquarie Harbour in western Tasmania and its major vegetation types. The environment is interpreted as estuarine with a range of subenvironments including estuarine mouth bar, fully subtidal sands, tidal flat with mangroves, and freshwater swamps. Supratidal freshwater swamp forest (sometimes conifer‐dominated) was fringed with Nypa mangrove swamps in the high tidal regions. Non‐vegetated tidal mud and sand flats occurred in regions with longer tidal submergence. The Macquaríe Harbour beds are given formation status and the Strahan Sand Member is defined.  相似文献