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1.
本文应用同位素示踪和γ能谱测定方法,就海水对近岸沉积物中放射性同位素~(90)Sr(~(85)Sr)、~(137)Cs、~(60)Co及~(106)Ru的解吸性能进行了初步研究。海水对沉积物中四种同位素解吸性能的变化顺序为~(90)Sr(~(85)Sr)>~(106)Ru>~(60)Co>~(137)Cs,沉积物吸附的~(90)Sr(~(85)Sr)易被海水解吸,而~(137)Cs和~(60)Co则易被沉积物吸附固定。 相似文献
2.
南海近海海水中人工放射性核素 90Sr的含量及分布 总被引：1，自引：0，他引：1
在调查研究的基础上,通过对丰、枯水期海水中~(90)Sr含量变化的讨论,说明南海近海水中~(90)Sr的浓度与沿岸河水的流入有一定关系。 相似文献
3.
本文提供了1989～1991年广东近岸表层水中~(90)Sr和~(137)Cs含量的分析结果。在调查海区,~(90)Sr含量为2.31～3.75mBq/L,平均值为3.21±0.45mBq/L。~(137)Cs含量为2.10～4.49mBq/L,平均值为3.47±0.89mBq/L。~(137)Cs/~(90)Sr放射性的比值为0.63～1.69,平均值为1.11±0.35。调查结果表明,近三年来未发现广东近岸海域有明显的人工放射性污染。目前广东近岸海水中的~(90)Sr和~(137)Cs主要仍是以往核试验所产生的放射性落下灰残余。 相似文献
4.
针对当前使用的沉积物样品中~(90)Sr检测方法存在的操作繁琐、检测效率低的问题,建立用液闪谱仪快速检测~(90)Sr的方法。样品经微波消解后,用二-(2-乙基己基)磷酸(HDEHP)分离出~(90) Sr的子体~(90)Y,利用Bi_2S_3沉淀消除210Bi对测定结果的干扰,二次萃取后直接利用液体闪烁谱仪对其中~(90)Y活度进行测量。用标准试剂测定液闪谱仪测量样品总体积为8mL时的最佳萃取剂与闪烁液体积比为18∶2。改进的方法可节省样品检测时间10h以上,~(90)Y探测效率达到64%,沉积物样品质量活度探测下限达到0.103Bq/kg。通过测量样品源衰变曲线计算的~(90)Y半衰期为64.05h,与国际计量局(BIPM)核数据专集中的国际评估值64.04h在不确定度范围内一致。 相似文献
5.
人工放射性核素及其地球化学行为的研究已成为当前海洋科学的重要内容之一。由于~(90)Sr是重要的裂变产物,在沉积化学、地球化学、海洋环境学和生物学的研究中都具有较重要的意义,故各国均比较重视。据统计,关于海水中~(90)Sr问题的研究最多,而沉积物较少。1981年,我们对渤海湾沉积物中的~(90)Sr进行了初步调查,根据所获资料,讨论了其分布规律和转移方式以及造成不同放射水平的原因。 相似文献
6.
海水中NH_4-N的测定,经历了奈氏法、靛酚兰法,直到目前的氧化法各阶段。在氧化法中所使用的氧化剂有次氯酸钠和次溴酸钠。李逢熙曾对这两种方法进行过比较研究,认为次溴酸盐氧化法(以下称溴法)快速灵敏、转化率高、精密度和准确度较好。1984年溴法被列入《海洋污染调查暂行规范》,被海洋界和 相似文献
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8.
目前,在大气中实验核武器的次数虽已人为减少,但估计还会有700万居里的~(90)Sr存留在30公里的高空中,此量足以沉降到本世纪末;近年来,由于核动力船只和沿海核企业大量增加,致使更多的放射性废物进入海洋。因此,海水中一直存在着溶解状态的长寿命的~(90)Sr。这样,对于~(90)Sr的分析,就仍然是海洋放射性 相似文献
9.
对海南岛南岸三亚湾海水2008~2009年周间隔取样,用全谱直读等离子体原子发射光谱(ICP-AES)分析方法对其Sr、Mg、Ca的含量m(Sr)、m(Mg)、m(Ca)进行了测定。结果显示,m(Sr)/m(Ca)=8.558×10-3~9.227×10-3、m(Mg)/m(Ca)=4.924~5.403,与全球各大洋和主要珊瑚礁区有明显的高异常偏差,而且在春末夏初和秋末冬初两个过渡期,三亚湾海水m(Sr)/m(Ca)波动幅度比m(Mg)/m(Ca)相对较大,且体现了一定的差异性。在此基础上,结合海水的m(Sr)/m(Ca)、m(Mg)/m(Ca)在时间和地域空间上的变化对珊瑚温度计标定的影响,对不同站点建立的珊瑚m(Sr)/m(Ca)温度计进行了重新校正,并与分配系数法对比分析,我们认为利用珊瑚的m(Sr)/m(Ca)、m(Mg)/m(Ca)重建古海水表面温度(SST)记录时必须综合考虑包括海水微量元素比值变化在内的各种影响因素对温度计标定的干扰,为进一步了解气候环境演变具有重要意义。 相似文献
10.
在海洋环境中,放射性核素~(90)Sr和~(137)Cs的测定占有重要的位置。 研究~(137)Cs/~(90)Sr比值,有助于了解这两个核素的地球化学过程、分馏现象以及在海洋中的归宿。同时,还可以根据其比值和其中一个核素的含量,推算出另一个核素的浓度。 一、核爆炸后的~(137)Cs/~(90)Sr比值 1965年,Harley等人根据百万吨级的核 相似文献
11.
《Oceanologica Acta》1998,21(6):983-992
To improve the knowledge of the survival of enteric viruses in a marine environment, the influence of physico-chemical parameters (temperature, UV, salinity) on the survival of infectious poliovirus 1 and hepatitis A virus (HAV) in seawater was first studied, the influence of suspended solids (SS) on poliovirus adsorption and survival in seawater was then evaluated and the detection of rotavirus genome in environmental samples (shellfish, river water, treated wastewater) was finally investigated. The results show that temperature has a major impact on virus survival in seawater as the time necessary to inactivate 90 % of the virus (T90) is 671 days at 4 °C and only 25 days at 25 °C. Ultraviolet light (42 mW s cm−2) rapidly inactivates viruses but HAV is more resistant (T90 = 2.6 min) than the poliovirus 1 (T90 = 1.3 min). By contrast, seawater salinity has no effect on virus survival. In presence of SS, 90 % to 99.9 % of the viruses were adsorbed. This adsorption does not provide any protection for viruses with low SS concentrations (3 and 15 mg L−1) but a slight increase in virus survival was observed with a high SS concentration (500 mg L−1). Finally environmental sample analysis indicated that 20 % shellfish, about 40 % river water and 40 % treated wastewater tested positive for the rotavirus genome. 相似文献
12.
本研究提出了一种用于检测海水中锌离子(Zn2+)含量的电化学检测方法。该方法首先应用水热法合成SiO2@PDA-Sb复合材料,然后将该复合材料修饰到玻碳电极上制备SiO2@PDA-Sb-Nafion/GCE,利用差分脉冲阳极溶出伏安法(DPASV)对珠江口海水水样中Zn2+进行测定。研究结果表明,Zn2+在SiO2@PDA-Sb-Nafion/GCE上具有较强的溶出峰。在最优条件下,SiO2@PDA-Sb-Nafion/GCE对Zn2+浓度在1～1 000 nmol/L范围内可实现灵敏、准确的检测,Zn2+的检测出限为0.71 nmol/L。加标回收率实验显示Zn2+加标回收率为93.19%～100.12%,表明该方法可应用于现场海水样品Zn2+测定。本方法具有电极制作简单、稳定性和抗干扰性良好,能够提高现有测定方法的检测限和精确度,在现场海水检测... 相似文献
13.
A method is described for the determination of Th isotopes (232Th,230Th,228Th and227Th) in seawater through analysis of Th adsorbed on MnO2-impregnated fiber that has been moored in the deep sea for up to 10 months. Since the MnO2-fiber adsorbs Th from seawater at a constant rate, natural234Th can be used as a yield monitor by making a correction for its decay during the period of deployment. The results obtained by the method showed good reproducibility and accuracy. The method has the advantage over the chemical coprecipitation method that the time and labor for sampling and processing a large-volume of seawater is reduced. 相似文献
14.
An ion-exchange technique was used to concentrate ammonia from seawater. Precipitation of bivalent cations, prior to concentration, reduced the variability of ammonia recovery from the ion-exchange column and lengthened column life. Analysis of the eluate was by the phenolhypochlorite reaction. The method was designed for use with small seawater samples (>10ml) and has the advantage that it can be adapted for use with small volumes of seawater with no loss in sensitivity. In a 10 ml seawater example NH3-N concentrations of 10–150 μg l?1 were accurately determined. 相似文献
15.
The concentrations of total lead were determined in both ordinary coastal seawater and in coastal waters highly polluted with sewage. The average concentration of total lead ranged from about 25 ng/kg in surface samples of the former type to an average of 150 ng/kg in the latter type. 0.4−μm filtrate lead was found to be equivalent to lead extracted from untreated seawater by dithizone in chloroform. In highly polluted waters, particle lead ranged from 56 to 39% of the total lead, with the proportion increasing as the amount of sewage in the seawater increased. Virtually all of the lead in sewage is contained in the particle phase before it enters the ocean but about 11% is made freely available by cation exchange when the sewage is mixed with seawater. In ordinary coastal waters that are not highly polluted with sewage lead, particle lead ranged from 90 to > 20%, and most of this lead was associated with plankton. About one-third of total lead, or one-half of particle lead, in untreated seawater adheres to the walls of the water container within the first day. Upon prolonged standing (> 3 months) most of the remaining particle lead can be collected on the surface of algal colonies growing on the walls of the water container. The concentrations of freely available lead in seawater do not seem to be significantly affected by wall adsorption. The 206Pb/207Pb ratio of total lead in coastal surface seawater collected near Los Angeles was 1.194, and a day earlier was 1.188 near La Jolla. It is believed that this shows lack of mixing of contributions from two different sources of lead pollution: a pulse of rain-storm runoff of gasoline lead(206Pb/207Pb 1.197) from paved surfaces added to Los Angeles waters; and sewage lead (206Pb/207Pb 1.188) from San Diego added to La Jolla waters. 相似文献
16.
Boron isotopic fractionation during seawater evaporation 总被引：6，自引：0，他引：6
Y.K. Xiao S.Z. Li H.Z. Wei A.D. Sun W.G. Liu W.J. Zhou Z.Q. Zhao C.Q. Liu G.H. Swihart 《Marine Chemistry》2007,103(3-4):382-392
Laboratory experiments were undertaken to investigate the behaviour of boron at the seawater–air interface during seawater evaporation. Seawaters adjusted to different pH values were heated to 27, 33 and 40 °C inside a quartz evaporator. The vapor was collected with a quartz condenser using a cold trap. A natural seawater–vapor process in quiet air conditions and excluding the sea-spray component was realized using this arrangement. The results indicate an enrichment of 11B in the condensate. This implies that in the natural environment, rainfall with δ11B values lower than that of seawater has been affected either by continental boron sources or by the boron extracted from seawater under airflow conditions. While the net flux of boron carried away from the ocean by air masses due to seawater evaporation is significant compared to other fractionation-associated processes removing boron from the ocean, the effect of isotopic fractionation as boron enters the vapor phase on the isotopic composition of boron in the ocean over time is small. 相似文献
17.
An analytical method is proposed for the direct determination of Cd in seawater by differential pulse anodic stripping voltammetry and the derivative technique with a hanging mercury drop electrode. The process of determination is quick, simple and convenient. The concentration of Cd in seawater is only determined by adjusting the acidity of seawater to pH 2 and by taking three minutes' plating time. Sensitivity of the method is about 1×10-10M, and accuracy of that satisfactory. Relative standard deviation is about 12% when the concentration of Cd in seawater is approximately 0.04 ppb. A good agreement was obtained by a standard curve and a standard addition technique respectively from determining Cd in the same seawater. Actual measurement time per sample is about 10 min. 相似文献
18.
《Marine Chemistry》2001,73(2):113-124
Dissolved boron in seawater occurs mainly in the form of boric acid (B(OH)3) and borate (B(OH)4−). While the equilibrium properties of the dissociation of boric acid have been studied in detail, very little work has focused on the kinetics of the boric acid–borate equilibrium in seawater. Here, we present a theoretical study of the relaxation of the seawater borate–carbonate system towards equilibrium using the experimental data of Mallo et al. [Nouv. J. Chim. 8 (1984) 373] and Waton et al. [J. Phys. Chem. 88 (1984) 3301]. The reaction rate constants are two to four orders of magnitude smaller than typical rate constants of diffusion-controlled reactions of other acid–base equilibria. This is presumably due to the substantial structural change that is involved in the conversion from planar B(OH)3 to tetrahedral B(OH)4. The time required to establish the boric acid–borate equilibrium in seawater is calculated to be ∼95μs at temperature T=25°C and salinity S=35. Considering stable boron isotopes 11B and 10B, the isotopic equilibration time is ∼125 μs. As a result, kinetic isotope effects during coprecipitation of boron in calcium carbonate are unlikely and therefore do not affect the use of stable boron isotopes as a paleo-pH recorder. 相似文献