Determination of trace metals accumulated and internalized by marine phytoplankton; interferences with colloidal organic matter

In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the diatom Thalassiosira weissflogii. Two methods commonly used for collection of algae to analyse metal content, filtration and centrifugation, were compared, and a procedure to differentiate the metal internalized by the alga from that adsorbed to cell walls-washing with 0.01?M ethylenediaminetetraacetic acid (EDTA)- was optimized for its use in seawater and in the presence of humic acids. The present results highlight the possibility of obtaining biased results if filtration is used to isolate the algae, and show that centrifugation is a more suitable procedure minimizing contribution of particulate and colloidal forms of metals to the measured cellular and intracellular metal contents. Thus a combination of centrifugation to isolate the algae from the medium with a 10 minutes washing with a washing agent composed of EDTA 0.01?M at pH 8 and NaCl and KCl to 0.5?M ionic strength is recommended to extract metals adsorbed to the surfaces of marine phytoplankton for a seawater containing humic substances. The importance of discriminating between internalized metal and total cellular metal in bioavailability studies is noted, given the different effects of humic substances on metal accumulation in the different cellular pools.     

Electrochemical studies on the corrosion of brass in seawater under anaerobic conditions

This paper reports an electrochemical study on the corrosion of brass in deoxygenated nonbuffered and buffered natural and artificial seawater solutions under anaerobic conditions. Cyclic voltammograms of brass and copper in natural seawater (NSW) and artificial seawater (ASW) were obtained in the passive and transpassive potential regions. The corrosion resistance of brass in natural and artificial seawater was evaluated, and open-circuit potentials were recorded over exposure period of 1 week. Brass samples from 3-month exposures in deoxygenated nonbuffered ASW and NSW, under open-circuit potential, have been imaged by scanning electron microscopy, and the elemental composition of the corrosion products was obtained by energy dispersive spectrometry analysis. It has been concluded that, under anaerobic conditions, the aggressivity of NSW is higher, with brass being less resistant to corrosion than copper, and that buffer contributes to reduce the aggressivity of both media.     

高活化铝合金牺牲阳极材料的研制

通过添加锌、铟、锡、镓等合金元素和适当的冶炼工艺，研制成功了工作电位负于－１．４０Ｖ（ＳＣＥ）、实际电容量≥２１７５Ａ．ｈ／ｋｇ、表面活性高、溶解非常均匀的铝合金牺牲阳极、该铝合金牺牲阳极在海水、淡海水介质中具有优异的电化学性能，可全面替代镁合金牺牲阳极、具有较高的技术经济优势。     

Binding of uranyl ion by 2,2′-dihydroxyazobenzene attached to crosslinked polystyrenes covered with highly populated quaternary ammonium cations

2,2′-Dihydroxyazobenzene (DHAB) derivatives were attached to poly(chloromethylstyrene-co-divinylbenzene) (PCD) because of the high affinity of DHAB for uranyl ion. Chloromethyl groups of PCD were converted to quaternary ammonium ions by treating them with tertiary amines. Two strategies were adopted to improve the uranyl-binding ability of the immobilized DHAB: (1) the creation of a highly cationic microenvironment around the DHAB moieties and (2) the introduction of electron-withdrawing groups to DHAB. Capacity of the resins for uranyl uptake was measured, revealing that about 10 to 46 mg of uranium could be complexed to 1 g of the resins. Formation constants (K_f) for the uranyl complexes of the resins were determined. In the presence of ≥0.02 M bicarbonate ion at pH 8.02, log K_f values of 14.3 to 15.8 were obtained. Uranium extraction from seawater with two kinds of resins prepared in this study was carried out on the east coast of the Korean peninsula. The amount of uranium extracted from seawater was up to 150 μg/g resin. Thus, the uranium-extracting capability of the DHAB-containing polystyrene resins was improved significantly by the structural modifications. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4117–4125, 1999     

Biodegradation Potential of Bacillus sp. PAH-2 on PAHs for Oil-Contaminated Seawater

Microbial degradation is a useful tool for inhibiting or preventing polycyclic aromatic hydrocarbons (PAHs) widely distributed in marine environment after oil spill accidents. This study aimed to evaluate the potential and diversity of bacteria Bacillus sp. PAH-2 on Benzo (a) anthracene (BaA), Pyrene (Pyr), and Benzo (a) pyrene (BaP), their composite system, aromatic components system, and crude oil. The seven-day degradation rates against BaA, Pyr, and BaP were 20.6%, 12.83%, and 17.49%, respectively. Further degradation study of aromatic components demonstrated PAH-2 had a high degradation rate of substances with poor stability of molecular structure. In addition, the degradation of PAHs in crude oil suggested PAH-2 not only made good use of PAHs in such a more complex structure of pollutants but the saturated hydrocarbons in the crude oil also showed a good application potential.     

Determination by Fluorescence Spectroscopy of Cadmium at the Subnanomolar Level: Application to Seawater

This paper reports the development of a molecular fluorescence spectroscopy-based approach for the determination of cadmium in seawater. Anthrylazamacrocycle derivatives—the fluorescence of which is enhanced when chelated to zinc or cadmium—are used as chemosensors. A detection limit of 5 nM has been found at pH 10 for both metals, and spectral shifts allow simultaneous Cd(II)/Zn(II) determination using multiwavelength analysis. While cadmium emission behavior is similar at pH 13, zinc is not detected anymore. This enables the selective detection of cadmium even at a high Zn(II)/Cd(II) ratio. The detection limit is 1 nM. Interferent removal and preconcentration have been developed using a Dowex resin, with a view to determine cadmium in seawater. A global procedure including interferent elimination, cadmium preconcentration (30 fold), and fluorescence detection at pH 13 has been evaluated on certified reference material SLEW-2.     

利用导电涂膜直接电解海水法防护生物腐蚀1模拟和测量技术

基于电化 学微探针 和微弱 信号检测 技术, 采用 四电 极体 系、双恒 电 位仪、锁相 相 关测定系统 以及三维 微调装 置建立模 拟和测量 系统,将 首次实 现对利 用导 电涂 膜直 接电 解海 水法 防护生物腐 蚀中微 米尺度内 痕量 Ｃｌ Ｏ － 浓度 的测量．本 文报道 了模拟和 测量实验 的阶段 性进展．     

Comparison of the Content of Several Elements in Seawater,Sea Cucumber Eupentacta fraudatrix and Its High-Molecular-Mass Multiprotein Complex

Metal ions and other elements play many different critical roles in all biological processes. They can be especially important in high concentrations for the functioning of organisms living in seawater. It is important to understand how much the concentrations of different trace elements in such organisms can be higher than in seawater. Some marine organisms capable of rapid recovery after different injuries are fascinating in this regard. Sea cucumbers Eupentacta fraudatrix can completely restore all organs and the whole body within several weeks after their division into two parts. Here, for the first time, a comparison of the content of different elements in seawater, sea cucumber, and its very stable multiprotein complex (2000 kDa) was performed using two-jet plasma atomic emission spectrometry. Among the 18 elements we found in sea cucumbers, seawater contained only six elements in detectable amounts, and their content decreased in the following order: Mg > Ca > B > Sr ≈ Si > Cr (0.13–930 µg/g of seawater). The content of these elements in sea cucumbers was higher compared with seawater (-fold): Ca (714) > Sr (459) > Cr (75) > Si (42)> B (12) > Mg (6.9). Only four of them had a higher concentration in the protein complex than in seawater (-fold): Si (120.0) > Cr (31.5) > Ca (9.1) > Sr (8.8). The contents of Mg and B were lower in the protein complex than in seawater. The content of elements additionally found in sea cucumbers decreased in the order (µg/g of powder) of P (1100) > Fe (47) > Mn (26) > Ba (15) > Zn (13) > Al (9.3) > Mo (2.8) > Cu (1.4) > Cd (0.3), and in the protein complex, in the order of P (290) > Zn (51) > Fe (23) > Al (14) ≈ Ni (13) > Cu (7.5) > Ba (2.5) ≈ Co (2.0) ≈ Mn (1.6) > Cd (0.7) >Ag (0.2). Thus, sea cucumbers accumulate various elements, including those contained in very low concentrations in seawater. The possible biological roles of these elements are discussed here.     

In Situ Device for Detection of Oil Spill in Seawater

The purpose of this study was to design an innovative, real time, cost effective, and environment friendly in situ technique for the surface measurement of oil spill thickness. The technique was based on the concept of the electrical conductivity to characterize and to measure the thickness of an oil layer in seawater. The system was designed to monitor the seawater pollution continuously and to send an alarm if the oil level exceeds a certain limit. The results of this study are very important as they may contribute to the development of advanced practices in oil spill detection.     

偕胺肟基功能高分子膜对铀吸附过程的研究

将在铝阴极表面电聚合的聚丙烯腈(PAN)涂层经偕胺肟基化反应(pH=7,70℃,3h)得到含有偕胺肟基的功能高分子膜(AFPF),PAN中的-CN基团有64.7%转化为-C(NH2)=N-OH,并研究了AFPF对硝酸铀溶液中的铀吸附性能.实验结果表明,AFPF对标准溶液中的铀吸附过程分为静电吸附和螯合吸附,且以后者为主,静电吸附的Freundlich等温方程为:гe=0.080c-0.66,螯合吸附的Freundlich等温方程为:гc=38.64c0.26,总吸附的Freundlich等温方程为:гt=38.21c0.26,并用扫描电镜表征了AFPF吸附铀前后的形貌.