共查询到20条相似文献，搜索用时 312 毫秒
1.
2.
The ratio is at least a factor of two higher in the particulate phases of California coastal waters than the values previously reported for unfiltered waters and sediments. These results are attributed to a greater water solubility for plutonium relative to americium species. The values of the ratio in mussels indicate primarily a particulate uptake of these transuranics. Sorption experiments of these two elements from seawater to glass beads, rayon fibres and filter papers are consistent with an uptake of the particulate phases. 相似文献
3.
Results of the radiochemical determination of 239+240Pu and 238Pu in seawater, plankton, marine organisms and sediment are reported. The samples were collected in the Taranto Gulf, and the data are compared with those obtained from other stations in the Mediterranean Sea. The vertical distribution of plutonium isotopes in sediments is also presented and discussed. 相似文献
4.
S. R. Aston 《Marine Chemistry》1980,8(4):319-326
Thermodynamic considerations based on existing data from various laboratory studies of plutonium species in aqueous solution are used to predict the speciation of this radioactive pollutant in seawater. Oxidation-reduction data for plutonium suggest that Pu(VI) should be very dominant in seawater solution compared to Pu(IV), and that Pu(III) and Pu(V) should be absent. The disproportionation reactions and the alpha reduction mechanism are probably of no consequence to the oxidation state in seawater. However, the irreversible hydrolysis of Pu4+ and the associated formation of polymeric Pu(OH)4 colloids are important mechanisms of speciation control and plutonium removal to sediments, by adsorption onto suspended matter. Stability constants for plutonium complexation with inorganic ligands in seawater suggest that Pu(VI) dissolved in seawater will be dominantly PuO2CO3OH−.The theoretical predictions of plutonium speciation and behaviour in seawater are compared to the only available data on plutonium speciation in seawater (Nelson and Lovett, 1978). Good agreement between the predictions and field observations was obtained, within the limitations imposed by the scarcity of data on this subject. 相似文献
5.
Joan D. Willey 《Marine Chemistry》1978,7(1):53-65
Natural marine sediments can release dissolved silica to silica-poor seawater and can remove silica from seawater enriched with dissolved silica. These are fast reactions, with sufficient reaction occurring within the first 48 hours to indicate clearly the direction of the reaction. The relative importance of these two processes varies with the ratio of clays to biogenic silica in the sediment. Both the release and the uptake reactions approach the interstitial water concentration of dissolved silica as an end point, which suggests that these reactions may influence this concentration. No change in sediment reactivity with respect to silica uptake or release reactions was observed with increasing depth in core for the three sediment cores investigated; this indicates that uptake sites are not saturated, and silica is available for dissolution for a long time after deposition. 相似文献
6.
根据2011年6月茅尾海生态环境调查资料,对该海域海水和表层沉积物中叶绿素a的空间分布进行了分析。结果表明,海水叶绿素a变化范围1.384~4.060 mg/m3,平均值为2.143 mg/m3,表层沉积物叶绿素a范围为0.006~0.740 mg/kg(湿重),均值为0.124 mg/kg;海水与表层沉积物叶绿素a均呈现自河口向南逐渐降低的空间分布特征。单位面积表层沉积物叶绿素a平均含量为上方水柱叶绿素a平均含量的129.44%,沉积物对该海域初级生产力有显著的潜在贡献。相关分析表明,海水和沉积物叶绿素a均与无机氮及底栖动物栖息密度呈显著或极显著的正相关关系(P0.05或P0.01)。 相似文献
7.
基于室内物理模拟实验, 对长江沉积物进行淡水和海水环境下沉积物搬运过程碳释放通量实验模拟。结果表明, 模拟实验初期, 淡水和海水均为大气CO2的源, 但淡水CO2释放通量略高于海水;淡水、海水两种环境下, CH4释放通量均较小, 为弱释放-弱吸收过程。对两种环境下碳通量对比研究发现,Eh 值可能是造成淡水和海水环境下CO2通量差别的主要原因, 而pH 值可能对CO2通量差别的影响较小。两种环境下温室气体通量差别的具体原因仍需进一步研究。通过模拟对比试验, 旨在为系统地认识长江流域水库的温室效应与减排提供科学依据, 为我国清洁水电能源发展提供理论参考。 相似文献
8.
Surface intertidal sediments from 35 sites in the Irish Sea have been analysed for their 238Pu and 239,240Pu activities, together with an intensive study of plutonium in sediments of the Esk Estuary (NW England). The range of plutonium activities for the whole survey were 0·14–4118 and 1·3–16 026 Bq kg−1 for 238Pu and 239,240Pu, respectively. The levels of Pu activity, derived from the Sellafield nuclear fuel reprocessing effluents, in sediments are controlled by lithological factors and the influence of transport and post-depositional processes. Grain size distribution is particularly important, the major part of plutonium activity being in the mud fraction of all sediments.The data suggest that over the Irish Sea coastline, dynamic mixing of sediment grains by reworking and resuspension and/or by dispersion in tidal currents are important in determining plutonium distributions. The exponential decrease in sediment plutonium activities away from the Sellafield source is attributed to the progressive mixing with older contaminated and uncontaminated sediments. 相似文献
9.
小角刺藻生长过程中溶解游离氨基酸含量在海水中的变化 总被引：2，自引：1，他引：2
于1986年12月-1987年2月在温度为25±1℃下培养小角刺藻，以HPLC法测定该藻在培养过程中海水的溶解游离氨基酸（DFAA）含量变化。结果表明，小角刺藻不仅是海水中DFAA的主要生产者，而且也是DFAA的消耗者。小角刺藻不仅在缺乏硝酸盐的时候要吸收DFAA，即使在硝酸盐充足的情况下也会吸收。在小角刺藻的生长初期，水体中DFAA的含量迅速降低，而在后期却又大大增高。在小角刺藻的不同生长阶段，水体中DFAA的组成也不同。这些都可以说明海洋中DFAA的含量、组成和地区分布是密切地同浮游植物群落的繁殖消亡过程相关联的。 相似文献
10.
Katharine R. Hendry Michael P. Meredith Christopher I. Measures Damien S. Carson Rosalind E.M. Rickaby 《Estuarine, Coastal and Shelf Science》2010
The use of dissolved Al as a tracer for oceanic water masses and atmospheric dust deposition of biologically important elements, such as iron, requires the quantitative assessment of its sources and sinks in seawater. Here, we address the relative importance of oceanic versus atmospheric inputs of Al, and the relationship with nutrient cycling, in a region of high biological productivity in coastal Antarctica. We investigate the concentrations of dissolved Al in seawater, sea ice, meteoric water and sediments collected from northern Marguerite Bay, off the West Antarctic Peninsula, from 2005 to 2006. Dissolved Al concentrations at 15 m water depth varied between 2 and 27 nM, showing a peak between two phytoplankton blooms. We find that, in this coastal setting, upwelling and incorporation of waters from below the surface mixed layer are responsible for this peak in dissolved Al as well as renewal of nutrients. This means that changes in the intensity and frequency of upwelling events may result in changes in biological production and carbon uptake. The waters below the mixed layer are most likely enriched in Al as a result of sea ice formation, either causing the injection of Al-rich brines or the resuspension of sediments and entrainment of pore fluids by brine cascades. Glacial, snow and sea ice melt contribute secondarily to the supply of Al to surface waters. Total particulate Al ranges from 93 to 2057 mg/g, and increases with meteoric water input towards the end of the summer, indicating glacial runoff is an important source of particulate Al. The (Al/Si)opal of sediment core top material is considerably higher than water column opal collected by sediment traps, indicative of a diagenetic overprint and incorporation of Al at the sediment–water interface. Opal that remains buried in the sediment could represent a significant sink of Al from seawater. 相似文献
11.
Sugars and uronic acids have been extracted from marine sediment and seawater by various hydrolysis techniques and analyzed by ion-exchange chromatography. All stages of the extraction methods were examined for sources of error arising from contamination, destruction and incomplete extraction. Tested were: (1) sample drying procedure; (2) acid hydrolysis, i.e., effect of different acids, variations in acid concentration and hydrolysis time, and effect of variations in organic and CaCO3 contents of sediment on the quantity of released sugars and uronic acids; (3) deionization, i.e., neutralization of acid by precipitation or by ion-exchange resins, separation of sugars from uronic acids; and (4) volume reduction, i.e., rotary evaporation, freeze-drying, effect of added glycerin. It is shown that the hydrolysis efficiencies of the acids tested varied with the nature of the organic matter in sediment. Simultaneous hydrolyses with different acids may give insights into the sources of the organic input and the environment of deposition. For all sediment types examined pretreatment with 72 w/w% H2SO4 gave the highest yields and is, thus the optimal hydrolysis method for sediment.Sugar and uronic acid yields from seawater varied with the type of acid used for hydrolysis. The highest yield for North Sea surface water was obtained with p-toluene sulfonic acid.Since most previous investigators employed non-optimal techniques, it is recommended that intercalibration studies be performed. 相似文献
12.
为了揭示苏北浅滩紫菜养殖区附着绿藻和绿藻微观繁殖体的分布现状,从2013年三月到五月份对苏北浅滩紫菜养殖区及附近海域进行航次调查。结果表明, 绿藻微观繁殖体在水体和沉积物中广泛分布,水体中的平均值为267株/L,沉积物中的平均值为43株/g。调查期间,紫菜养殖区筏架上附着绿藻的生物量持续增长。在紫菜筏架上发现有浒苔,缘管浒苔,盒管藻三种绿藻,其优势种为盒管藻,其次是浒苔。研究表明,绿潮发生早期在苏北浅滩海域存在绿藻微观繁殖体和附着绿藻,这将为中国绿潮治理提供理论支撑。 相似文献
13.
We measured tissue phosphorus content of high and low intertidal Hormosira banksii to test the hypothesis that tissue phosphorus content would be greater in individuals from the low intertidal because of greater total uptake associated with longer immersion in seawater. Moreover, we predicted that tissue phosphorus would be greater at sites where the seawater contained higher phosphate concentrations. There was a positive, linear relationship between local seawater phosphate concentrations and tissue phosphorus content of H. banksii from high and low intertidal zones at six different sites in winter. However, there were no comparable relationships in summer, even though the range of seawater phosphate concentration was similar in both seasons. The phosphorus contents of low intertidal H. banksii were significantly greater than high intertidal H. banksii in winter, but not in summer. Reasons for these differences may be related to greater access to seawater phosphate in low intertidal algae (than those in the high intertidal) in winter, followed by greater utilisation of the internal phosphorus between winter and summer, due to faster growth rates in the low intertidal. 相似文献
14.
Conny Haraldsson Leif G. Anderson Martin Hassellöv Stefan Hulth Kristina Olsson 《Deep Sea Research Part I: Oceanographic Research Papers》1997,44(12):2031-2044
A system for rapid, high precision potentiometric determination of alkalinity in sea water and sediment pore water is presented. Two titration units were used: a 40 ml unit for seawater and a small volume unit for sediment pore water. Titration time was normally less than 10 minutes per sample, including sample exchange. With a 40 ml sample volume, the relative standard deviation of the alkalinity obtained in the laboratory was 0.05% and at sea 0.1 %. The small-volume system (0.5–1.5 ml) gave a precision of 0.07%. Five titration points, in two groups after the second equivalence point, were used to evaluate the equivalence volume. Results from equilibrium calculations and computer simulated alkalinity titrations show that it was possible to use a non-modified Gran function [(V0 +v)*10(E/Z)] and still achieve good accuracy and precision. 相似文献
15.
Ronnie Nhr Glud Jens K. Gundersen Bo Barker Jrgensen Niels Peter Revsbech Horst D. Schulz 《Deep Sea Research Part I: Oceanographic Research Papers》1994,41(11-12)
Total O2 uptake rates were measured by the benthic flux chamber lander ELINOR, and O2 microprofiles were measured by the profiling lander PROFILUR in the eastern South Atlantic. Diffusive O2 fluxes through the diffusive boundary layer and the depth distribution of O2 consumption rates within the sediment were calculated from the obtained microprofiles. The depth integrated O2 consumption rate agreed closely with the diffusive O2 uptake at all stations. Total O2 uptake was 1.2–4.2 times the diffusive O2 uptake, and the difference correlated with the abundance of macrofauna in the sediment. Diffusive O2 uptake and O2-penetration depths correlated with the organic content of the sediments and exhibited an inverse correlation with water depth. Total and diffusive rates of in situ O2 uptake were higher than previously published data for shelf and abyssal sediments in the Atlantic, but were comparable to rates from upwelling areas in the eastern Pacific. Laboratory measurements on recovered sediment cores showed lower O2 penetration depths and higher diffusive uptake rates than in situ measurements. The differences increased with increasing water depth. We primarily ascribe this compression of O2 profiles to a transiently increased temperature during recovery and enhanced microbial activity in decompressed sediment cores. Total O2 uptake rates measured in the laboratory on macrofauna-rich stations were, in contrast, lower than those measured in situ because of underrepresentation and disturbance of the macrofauna. 相似文献
16.
作为高附加值水产养殖物种,仿刺参(Apostichopusjaponicus)的病害和病原微生物研究受到人们关注,但对其共生菌群组成、地域性差异及与水体环境间交流等方面的研究仍十分有限。本研究收集了来自中国、日本和韩国共786例仿刺参肠道、水体和沉积物的16SrRNA基因高通量测序数据,比较细菌群落组成以探寻仿刺参肠道微生物与环境和地域之间的关系。分析结果显示,尽管仿刺参肠道、水体和沉积物中各细菌组分的比例不同,但共有菌属甚多,表明仿刺参可以从外界环境大量获取微生物。与水体和沉积物的样本类型相比,仿刺参肠道微生物多样性最低且所含菌属的种类最少,进一步提示仿刺参肠道对外界来源的微生物进行了富集和筛选,其中变形细菌门(Proteobacteria)、假单胞菌属(Pseudomonas)、嗜冷杆菌属(Psychrobacter)和利斯顿氏菌属(Listonella)的富集尤为明显。中国、日本和韩国来源的仿刺参肠道微生物Alpha多样性无显著差异,但主坐标分析将它们聚为不同的簇,且各自拥有独特的细菌门类。比较中国渤海和黄海两个海区的仿刺参肠道菌群获得了相似的结果,体现出广泛的地域性差异。基于细菌分类的功能预测发现三个国家仿刺参肠道微生物均具有发酵、化能异养和需氧化能异养功能,表明共生菌群在功能上存在共性,并可能对宿主生理产生相同的作用。本研究揭示了仿刺参肠道微生物在不同地域之间存在明显差异,并且与水体环境之间存在着密切的联系,能够为仿刺参共生微生物及其与宿主健康的相关性研究提供基础性资料,并可能在自然循环过程和渔业资源保护过程中发挥作用。 相似文献
17.
Cornelis H. van der Weijden 《Marine Chemistry》1976,4(4):377-387
Experiments on the uptake of Zn and Cd by synthetic hydrous Mn oxides were carried out in an ionic medium at pH 3.5 and at pH 4. A slight preference for uptake of Cd2+ over Zn2+ was observed with both birnessite and nsutite, the Cd/Zn ratio being different for each mineral. Subsequently, the desorption of Zn and Cd from the obtained products in artificial seawater was studied. In this medium Cd is desorbed from the Mn oxides to a much higher extent than is Zn. The latter observations can be satisfactorily explained by the large difference of complex formation for the two metals in seawater, slightly counteracted by the preferential uptake of Cd2+ over Zn2+. The order of magnitude of the Zn/Cd ratio in natural manganese nodules is compatible with the ratio calculated on the basis of experimental results, taking fair estimates of the actual inorganic Zn/Cd ratio in seawater and of the pH of deep ocean water. 相似文献
18.
Mangroves are coastal ecosystems, found in tropical and subtropical regions around the world. They are found in the transitional zones between land, sea, and rivers. Petroleum hydrocarbons are the most common environmental pollutants, and oil spills pose a great hazard to mangroves forests. This research was focused on the isolation and characterization of crude oil‐degrading bacteria from mangrove ecosystems at the Persian Gulf. Sixty‐one crude oil‐degrading bacteria were isolated from mangrove samples (plant, sediment, and seawater) that enriched in ONR7a medium with crude oil as only carbon source. Some screening tests such as growth at high concentration of crude oil, bioemulsifier production, and surface hydrophobicity were done to select the most efficient strains for crude oil degradation. Molecular identification of strains was carried out by amplification of the 16S rRNA gene by PCR. The results of this study were indicated that the quantity of crude oil‐degrading bacteria was higher in the root of mangrove plants compare to other mangrove samples (sediment and seawater). Also, identification results confirmed that these isolated strains belong to Vibrio sp. strain NW4, Idiomarina sp. strain BW32, Kangiella sp. strain DP40, Marinobacter sp. strain DW44, Halomonas sp. strain BS53, and Vibrio sp. strain DS35. The application of bioremediation strategies with these bacteria can reduce crude oil pollution in this important marine environment. 相似文献
20.
海湾区海水中的溶存甲烷 Ⅰ.分布特征及成因 总被引：1，自引：0，他引：1
本文基于日本东京湾、伊势湾和浜名湖的调查资料，详细地讨论了海湾区海水中溶存甲烷的分布特征、成因及其来源。溶存甲烷在海湾中的分布主要受物理混合过程所控制；由河流携入和沉积物中产生是海湾区海水中溶存甲烷的两个主要来源。 相似文献