共查询到19条相似文献，搜索用时 187 毫秒
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本文基于日本东京湾、伊势湾和浜名湖的调查资料，详细地比较了这3个海湾海水中的溶存甲烷浓度、饱和度。表层海水中，溶存甲烷浓度以供名湖最高，达95nmol／dm3，伊势湾和东京湾相近，分别为41nmol／dm3和37nmol／dm3；其表层测定浓度是其平衡浓度的13～78倍，并分别计算了这3个海湾中甲烷的海气交换通量；用平均值外推法得出全球海洋环境中总的甲烷海气交换通量为6．3Tg／a。 相似文献
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利用Delft3D数学模型建立了平潭综合实验区近岸海域物质输运数学模型,模拟了澳前、海坛海峡北、海坛海峡南、流水、竹屿5个排污口在不同污水排放量下COD、无机氮浓度的分布．结果表明：在污水排放规模为3．0×10^4t／d时,竹屿排污口邻近海域海水COD、无机氮质量浓度分别为3．80、0．51mg／dm3,流水排污口邻近海域海水COD、无机氮质量浓度分别为3．60、0．42mg／dm3,都超过二类海水水质标准值,表明这2个海域水动力条件较弱、污染物扩散缓慢,不是理想的排污口．在污水排放量为1．5×10^5t／d时,海坛海峡北排污口邻近海域海水COD、无机氮质量浓度分别为1．87、0．28mg／dm3,海坛海峡南排污口邻近海域海水COD、无机氮质量浓度分别为1．84、0．27mg／dm3;澳前排污口在污水排放量为5．0×10^5t／d时,其邻近海域海水COD、无机氮质量浓度分别为2．48、0．28mg／dm3,均符合二类海水水质要求,表明上述海域水动力条件良好、纳污能力强、环境容量大,是较好的污水排放口．该研究可为平潭综合实验区海域污水排放口选址优化提供科学依据,为该海域入海污染物总量控制和海洋环境管理提供参考． 相似文献
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海水中丙烯酸的高效液相色谱法建立及应用 总被引：2，自引：0，他引：2
建立了一种测定海水介质中丙烯酸的高效液相色谱法。采用耐纯水相和较低pH的Agilent SB-Aq-C18柱(100 mm×4.6 mm i.d.,5 μm), 0.35%磷酸溶液(pH=2)为流动相,使用紫外检测器,检测波长为210 nm,外标法定量测定。丙烯酸的保留时间在14.2~ 14.9 min,方法的检出限为4 nmol/dm3(S/N=3),在0.01~10 μmol/dm3的范围内均有良好的线性关系,相关系数可达0.999 6,加标回收率为95.4%~98.1%,相对标准偏差为1.3%~1.6%(1.04~2.32 μmol/dm3)。采用0.2 μm滤膜重力过滤冷藏的办法来保存海水丙烯酸样品。检测出2011年5月份青岛近海海水中丙烯酸的平均浓度为(0.101±0.069) μmol/dm3;海洋微藻球形棕囊藻在整个生长周期内培养体系中丙烯酸的浓度为0.339~2.219 μmol/dm3。 相似文献
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采用阳极溶出伏安法(ASV)对1999年10月采自浙江省三门湾健跳港表层海水中溶解态铅的形态进行了分析,结果表明:海水中游离态铅的浓度为2.2 nmol/dm3,有机配位态则可分为两类,即PbL1和PbL2;两类有机配位体条件稳定常数的对数(logKpcobnLd1,pb2 和logKpcobnLd2,pb2 )分别为8.4和9.1;两类有机配位体浓度(L1和L2)分别为37.4 nmol/dm3和52.7 nmol/dm3,将上述结果与以往三门湾海区研究中海洋生物急性毒性试验结果和不同介质中铅含量进行对比可知,浙江三门湾健跳港海区表层海水中溶解态铅浓度对海洋生物是安全的,但个别底栖生物物种中较高的铅含量已影响到人类的食用安全。 相似文献
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冠瘤海鞘幼体附着和变态的离子控制 总被引：3，自引：0，他引：3
研究了人工海水中三种金属离子K+,Mg2+和Ca2+分别在不同浓度下对冠瘤海鞘(Styelaca nopusSavigny)幼体附着和变态的影响,同时采用K+通道阻滞剂TEA检验其可兴奋细胞膜上的K+通道特性,对冠瘤海鞘幼体附着和变态的离子控制机制进行初步探讨,结果表明:K+的浓度为20~40mmol/dm3时诱导幼体附着和变态的效果最佳,低于45 mmol/dm3和高于80mmol/dm3的K+浓度都表现出抑制效果;Mg2+浓度在0~32 mmol/dm3时显著促进幼体附着和变态,达88mmol/dm3时起抑制作用;在人工海水中无论添加或减少Ca2+,均有效抑制幼体变态.TEA不能阻抑增加K+的诱导作用,这表明冠瘤海鞘幼体可兴奋细胞膜上的K+通道对外部TEA不敏感.另外,人工海水中缺乏K+或Ca2+或K+浓度达80mmol/dm3都会对冠瘤海鞘幼体产生毒害作用. 相似文献
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讨论了中国第六次南大洋考察4条断面1个海湾计30个剖面海水中碘的赋存形式及化学形态的生物地球化学分布。结果表明，表层海水总无机碘含量分有值在0．267－0．443μmol／dm3之间；海水无机碘及碘酸根含量的垂直分布与营养盐关系密切，溶解有机碘分布则较稳定，其含量约为总无机碘的10％。真光层内浮游植物对碘的吸收同化速率为0．17μmol／（m2·d），悬浮有机颗粒中碘的结合量约为4．3μmol／m3，真光层内颗粒碘的下沉速率大于7．2d／m。根据讨论结果提出了测区真光层内碘循环的生物地球化学模式。 相似文献
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硒对钝顶螺旋藻生长的影响及其在细胞中的累积和分布 总被引：6，自引：0，他引：6
本文研究了硒对纯顶螺旋藻（Spirulinaplatensis）生长的影响及其在细胞生化组成中的分布。结果表明,当硒浓度低于50mg／dm3时,对钝顶螺旋藻生长的抑制作用不明显,在低浓度下（＜10mg／dm3）可促进其生长;当硒浓度超过50mg／dm3时则起抑制作用,高浓度对藻体起毒害作用。藻细胞中总硒含量与培养液中的硒浓度有关,在0～40mg／dm3范围内,硒含量随着培养液中硒浓度的增加而增加：从0mg／dm3的2．50×10-5（m／m,dw）到40mg／dm3的231．45×10-6（m／m,dw）,至50mg／dm3,又开始降低为174.26×10-6（m／m,dw）;硒在S．platensis生化组成中的分布,以蛋白质含量为最高,可达总硒的49．22％～71．49％,而脂类及碳水化合物-氨基酸中的含量则较低,分别为总硒含量的3．59％～6．18％和1．45％～2．56％,硒在各组成中的含量与培养液中的硒浓度有关,其变化趋势与总硒含量的一致。 相似文献
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George T.F Wong 《Marine Chemistry》1980,9(1):13-24
An oxidation state diagram was used to study the relative stability of inorganic iodine species in an aqueous system. It is shown that although iodate is the most stable form, iodide may exist as a metastable form in a basic solution. Molecular iodine may undergo disproportionation to form iodide and iodate. Results from laboratory studies suggest that molecular iodine is rapidly taken up by seawater, and hypoiodite is probably formed. Hypoiodite is also unstable in seawater, and may react with organic matter or undergo autodecomposition. Direct reactions between molecular iodine and organic matter were not observed. 相似文献
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Aerated solutions of potassium iodide in de-ionised water, of between 5–20% (w/v), were exposed to ambient spring sunlight to estimate the rate of photochemical production of molecular iodine from iodide and oxygen in seawater. This rate cannot be measured directly as other reactions, for example the reduction of molecular iodine by organic matter, interfere. Also, a parallel photo-oxidation, initiated by organic matter in real seawater, may also occur. The experiments yield a half-life for iodide in tropical surface waters of about 29 months suggesting that the reaction is insignificant. At this rate it will not compete effectively against the reduction of molecular iodine by organic matter, and hence molecular iodine should not appear. The experiments also consider the photo-oxidation by nitrate, and iodate, a combination of nitrite and oxygen, and eliminate significant interference by chloride, bromide and the phosphate buffer. The rate of photo-oxidation with each of the first three oxidations is found to be first order with respect to oxidant concentration. The variation of photo-oxidation rate with pH is also studied, with a brief investigation without conventional oxidant, where electron cage complexes still promote photo-oxidation. The photochemical action spectrum for these reactions in sunlight is shown to extend between 300 and 425 nm. The photo-oxidation of iodide by iodate is more interesting to marine chemistry as the photo-reduction of iodate. Nevertheless, the reduction-rate is judged to be several orders too low to be significant in seawater. The mechanism of the reactions are discussed and lessons drawn on the stability of potassium iodide solutions used in iodate analysis. The KI actinometer is recommended to those studying other photochemical systems activated by UV-A light as it is linear and very simple and reliable. 相似文献
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对国产第一批冷原子荧光测汞仪进行了改进,大大降低了原仪器的噪音,并进行了系列实验验证工作.改进后的冷原子荧光测汞仪,灵敏度高,与金捕集-冷原子吸收法具有相近的灵敏度,而该方法具有测定简便、快速等优点.探测限达到0.033n mol. 相似文献
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Anna M. Farrenkopf Michael E. Dollhopf Sinad Ní Chadhain George W. Luther III Kenneth H. Nealson 《Marine Chemistry》1997,57(3-4)
Shipboard incubations from the US JGOFS cruise to the Arabian Sea (TN045) March, 1995 showed evidence of iodate reduction in 0.45 μ (Gelman Supor membrane) filtered seawater samples collected from intermediate depths (200–600 m) within the oxygen minimum zone (OMZ). Inorganic chemical reduction of iodate in these samples was ruled out as no free sulfide was measurable and concentrations of ammonia and nitrite were found to be less than 5 μM. To examine whether the reduction of iodate observed at sea could have been the result of bacterial metabolism, reduction of iodate (IO3−) to iodide (I−) by Shewanella putrefaciens strain MR-4 was studied in artificial seawater using electrochemical methods. MR-4 is a ubiquitous marine bacterium which may be of considerable importance when considering redox zonation in the water column because it is a facultative anaerobe and may switch amongst a suite of electron acceptors to support metabolism. In all experiments MR-4 reduced all iodate to iodide. The rate of formation of [I−]in the culture followed pseudo-first order kinetics. This is the first report of the marine bacterial reduction of iodate where the concentrations of iodide and iodate were measured directly. Our results may help to explain the depth distribution of iodine speciation reported in productive waters like the Arabian Sea and for the first time couple iodine speciation with bacterial productivity in the ocean. 相似文献
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Jianrong Lin 《海洋学报(英文版)》2022,41(3):103-108
A new spectrophotometric method based on a liquid waveguide capillary cell for an enhanced detection was developed to measure nanomolar iodate concentrations. This method has a detection limit and precision of 1–2 nmol/L, which is equivalent to 10% that of conventional methods, a recovery of 97.7%–104.0%, and a working range of 10–120 nmol/L. Water samples were collected from three estuaries and one coastal ocean for testing, and the proposed technique detected as low as 11 nmol/L and 18 nmol/L ... 相似文献
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Toward assessing the biogeochemical significance of seaweeds in relation to dissolved iodine in seawater, the effect of whole seaweeds (Laminaria digitata and Fucus serratus) upon iodide and iodate, at essentially natural concentrations, has been studied. The weeds were carefully removed from the sub-littoral zone of the Menai Straits and exposed to iodide and iodate at their natural temperature (6 °C), but under continuous illumination. Laminaria digitata was found to decrease the concentration of iodate with an exponential rate constant of 0.008–0.24 h−1. This is a newly discovered process which, if substantiated, will require an entirely new mechanism. Generally, apparent iodide concentration increased except in a run with seawater augmented with iodide, where it first decreased. The rate constant for loss of iodide was 0.014–0.16 h−1. Meanwhile, F. serratus was found not to decrease iodate concentrations, as did L. digitata. Indeed, after ∼30 h iodate concentrations increased, suggesting that the weed may take in iodide before oxidising and releasing it. If substantiated, this finding may offer a way into one of the most elusive of processes within the iodine cycle – iodide oxidation. With both seaweeds sustained long-term increases of apparent iodide concentration are most easily explained as a secretion by the weeds of organic matter which is capable of reducing the Ce(IV) reagent used in determination of total iodine. Modelling of the catalytic method used is provided to support this contention. The possibility of developing this to measure the strain that seaweeds endure in this kind of biogeochemical flux experiment is discussed. A Chemical Oxygen Demand type of approach is applied using Ce(IV) as oxidant. The results of the iodine experiments are contrasted with the several investigations of 131I interaction with seaweeds, which have routinely used discs of weed cut from the frond. It is argued that experiments conducted with stable iodine may measure a different variable to that measured in radio-iodine experiments. 相似文献
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本文对TOA萃取剂萃取钍适宜的操作条件及萃取溶剂进行了试验,提出了TOA/苯萃取234Th的最佳条件: 在 1cm3含 234Th的 6mol/dm3 HNO3 溶液中,用体积比为 0. 5的TOA/苯溶液 2cm3 萃取,然后用 2cm3 1. 0mol/dm3 H2SO4反萃取,最高萃取率达 94%.对TOA/苯、TBP/煤油和TTA/苯这 3种萃取体系的萃取效率及其影响因素、萃取机理、成本等做了比较,认为 3种体系各有利弊,但均可有效地应用于相关的海洋学研究中. 相似文献
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The distributions of iodide, iodate and total iodine were determined along a transect from the Sargasso Sea and across the Gulf Stream to the continental shelf of the South Atlantic Bight during November 1990. The western boundary of the Gulf Stream at the outer shelf-upper slope was characterized by steeply sloping isotherms and isopleths of iodide and iodate, resulting from a dome of cold water that was rich in iodate and nearly devoid of iodide at the slope. Both the mid and the inner shelf were relatively well mixed vertically. The concentration of iodate in the surface waters decreased shoreward from >0.3 μM in the Sargasso Sea/Gulf Stream/outer shelf, to 0.29 μM in the midshelf, 0.19 μM in the outer-inner shelf and 0.11 /IM in the inner-inner shelf. Concomitantly, the concentration of iodide increased from <161 nM to 175 nM, 257 nM and 300 nM. The concentration changes were more abrupt in the inner-inner shelf within about 30 km from the shore. There was no evidence of significant concentrations of organic iodine. These distributions of iodide and iodate suggest that the South Atlantic Bight may act as a geochemical processor of dissolved iodine. Iodate is added to the shelf during topographically induced upwelling and frontal exchange with the Gulf Stream. In the shelf waters, iodate is reduced to iodide in situ. Iodide is exported from the shelf to the Gulf Stream which may eventually further transport it to the ocean interior. A ☐ model calculation suggests that 28% and 43% of the iodate added to the Bight and the inner shelf, respectively, are converted to another form in these waters, almost all of which is iodide. About a third of the reduction of iodate to iodide in the Bight occurs in the inner shelf. Thus, the inner shelf may be the most geochemically active zone within the Bight. The residence times of iodide relative to its production and that of iodate relative to its removal are 3.1 and 3.6 months in the Bight and 0.9 and 1.8 months in the inner shelf. 相似文献
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Existing methods for the determination of the various forms of iodine present in seawater are laborious or unwieldy in use. This paper describes modified forms of the iodate and total iodine methods described by Barkley and Thompson (1960), a spectrophotometric procedure for iodate determination derived from Johannesson's (1958) work, and an automatic method for total iodine determination. Procedures for iodate and total-iodine determination which are suitable for use aboard ship, are recommended. Both procedures for iodate determination returned a standard deviation close to 0.5 μg/l when several replicate samples of a seawater containing approximately 30 μg/l of iodate-iodine were analysed. The automatic method for total iodine determination yielded a standard deviation of 0.8 μg/l by the repeated analysis of a seawater containing a total of approximately 50 μg/l of iodine. Suitable methods for the filtration and storage of seawater are also described. 相似文献