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1.
The content of selenium and its chemical form in sea water   总被引：1，自引：0，他引：1  
By using the new fluorometric method of determination of the total selenium ( Se), Se (IV) and Se (VI), the content of selenium in sea weter was determined in the western North Pacific. Results showed that the content of Se in surface water ranged from 0.06 to 0.12g l–1, while in deeper layers, the content increased to 0.20g l–1. It was found that Se (IV) showed rather uniform distribution with depth, while Se (VI) increased with depth to about three times that in the surface. The ratio of Se (IV) to the Se ranged from 0.5 to 0.8 in the surface and 0.4 to 0.6 in the deep. The coexistence of the hexa- and tetravalent ions of selenium was confirmed both in surface and deep layers. Some results of observations on the content of selenium in the coastal areas of Japan were also reported.  相似文献   

2.
Dissolved selenium in the Changjiang(Yangtze) Estuary and its adjacent waters was determined by hydride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorption-desorption process and biological role. In surface water, Se(IV) concentration ranged 0.05–1.14 nmol/L and Se(VI) concentration varied 0.01–1.20 nmol/L, with the means of 0.76 and 0.49 nmol/L, respectively. In bottom water, Se(IV) content varied 0.03–0.27 nmol/L and Se(VI) content ranged 0.04–0.85 nmol/L, with the averages of 0.10 and 0.40 nmol/L, respectively. High level of Se(IV) was observed near the shore with a significant decrease towards the open sea, suggesting the continental input from the adjacent rivers. Large value of Se(VI) was found in bottom water, reflecting the release from suspended sediment. Besides, high value appeared in the same latitude of the Changjiang Estuary and Hangzhou Bay illustrated the effect of lateral mixing and the long-distance transport of selenium. Se(VI), more soluble, occupied higher percentage in aqueous environment. The presence of Se(IV) resulted from the degradation of residue and the reduction of Se(VI) under anaerobic condition. The positive relationship to suspended particulate material(SPM) and negative correlation to depth indicated that Se(IV) tended to be released from the high density particulate matter. Instead, Se(VI) content did not significantly relate to SPM since it generally formed inner-sphere complex to iron hydroxide. Se(IV) content negatively varied to salinity and largely depended on the freshwater dilution and physical mixing. While, Se(VI) level deviated from the dilution line due to the in situ biogeochemical process such as removal via phytoplankton uptake and inputs via organic matter regeneration. As the essential element, Se(IV) was confirmed more bioavailable to phytoplankton growth than Se(VI), and moreover, seemed to be more related to phosphorus than to nitrogen.  相似文献   

3.
A red tide due toGymnodinium nagasakiense was observed in August 1988 in Tanabe Bay, Wakayama Prefecture, Japan. The maximum cell concentration ofG. nagasakiense reached 1×105 cells ml–1 at the surface water. From May to September 1988, the following were monitored: water temperature, salinity, chlorophylla, D.O., dissolved nutrients (NO2–N, NO3–N, NH4–N, PO4–P DON, DOP), particulate nutrients (PON, POP) and three dissolved selenium species [Se(IV), Se(VI), Organic Se]. Dissolved inorganic nitrogen (NO3–N, NH4–N) decreased but PON, POP, DON, DOP and inorganic phosphate increased at the peak of the bloom. The concentration of organic selenium increased up to the bloom initiation period which started on 5 July, and then the concentration of Se(IV) increased as the concentration of organic selenium decreased at the peak of the bloom (3 August). The strong relationship was found between the concentration of Se(IV) and the cell concentration ofG. nagasakiense (r 2=0.98). The Se(IV) requirement ofG. nagasakiense was 2.89×10–17 moles cell–1, which was agreed well with 4.4×10–17 moles cell–1 found in a laboratory experiment onG. nagasakiense using selenium spiked artificial sea water medium. The average ratio of Se(IV) to dissolved inorganic nitrogen (DIN) during the red tide bloom was 11441, the ratio of Se(IV) to DIN at the surface with the maximum cell concentration ofG. nagasakiense of 1×105 cells ml–1 was 1137. These results suggested that selenium may play an important role in red tide outbreak ofG. nagasakiense.  相似文献   

4.
The concentrations of total selenium (Se) and Se (IV) were determined in the surface waters of 30 stations located in the James River and southern Chesapeake Bay. The concentrations of total Se and Se (IV) ranged from 0·28 to 1·91 nM and from 0·07 to 1·36 nM, respectively, between salinities of 31·78 and 0·06‰. The concentration of Se (VI), calculated as the difference between the concentrations of total Se and Se (IV), ranged from 0·08 to 0·67 nM. While total Se seemed to be conservative in this study area at salinities above 0·36‰, Se (IV) might have been removed during estuarine mixing. The removal of Se (IV) occurred primarily at salinities below 4‰ possibly via the oxidation of Se (IV) to Se (VI).  相似文献   

5.
In order to clarify the chemical forms of minor metallic elements occurring in the ocean, a new method of separation of organic compounds of metals in sea water by using XAD-2 resin was contrived. By applying the new method of determination, it is found that, (1) More than 80 % of V, Fe, Cd and Cu dissolved in sea water are present in organic forms regardless of the depth; (2) A most part of Co and Pb are present in organic forms near the surface, but they change into inorganic forms in the deep layer up to 50 to 60%; (3) Of the total amounts of dissolved Al, Ni, Zn, Ag, Mo, and U, less than 30 % are present in organic forms in sea water anywhere in the ocean; (4) Up to 45% of Se is in organic forms.  相似文献   

6.
90Sr,106Ru, natural strontium and major elements were studied in 12 samples of beach deposits from Togi, Fukuura and Shiga, and in 26 samples of shallow water sediments from sea off Fukuura, Noto Peninsula, Ishikawa Pref., Japan.The average contents of natural strontium and90Sr in the beach deposits were 488 ppm ranging from 247 to 1,550 ppm and 45±9 pCi kg–1-dry mud ranging from 18 to 72 pCi kg–1-dry mud, respectively. While the average contents of natural strontium,90Sr and106Ru in the sediments were 234 ppm ranging from 136 to 415 ppm, 22±6 pCi kg–1-dry sand ranging from 7 to 48 pCi kg–1-dry sand and 0.6 ±0.2 nCi kg–1-dry ranging from 0.3 to 1.2 nCi kg–1-dry, respectively.The average contents of each natural strontium and90Sr in the beach deposits were about two times higher than those in the shallow water sediments. But no obvious relation of natural strontium to90Sr was found in all the samples. The enrichment of90Sr and108Ru in the beach deposits or tthe sediments were as high as 150320 and of 2,0003,000 compared with average contents of90Sr and106Ru in a liter of surface water from the Japan Sea. It is to be noticed that the average106Ru to90Sr ratio of 27 for the shallow water sediments is much higher than the average of 1.0 for surface sea water of the Japan Sea.As to major elements of the samples, the beach deposits are rich in silicon (Av. 70.89 ±0.92% SiO2), but poor in iron (Av. 2.99±0.32% Fe2O3). Whereas the shallow water sediments are poor in silicon (Av. 52.96±10.33% SiO2) and rich in iron (Av. 5.50±1.90% Fe2O3), calcium (Av. 9.64±9.22% CaO) and magnesium (Av. 2.83±1.58% MgO).  相似文献   

7.
A method for determination of malathion in natural water by cathodic stripping voltammetry using mercury film electrode is suggested in this paper. The method is based on the quantitativeformation of group generated by malathion as a result of elimination reaction inthe ethanol solution of sodium hydroxide. The group is similar to sulphide in electrochemical properties, and can be determined by cathodic stripping voltammetry. Interference from inorganic sulphide is prevented by the addition of Hg (NO3)2. This method has been applied to the determination of residual malathion in natural water (e. g. the sea, rivers, lakes, etc.). The waveheight is directly proportional to the malathion concentration within the range 5×10-9 - 1×10-7 mol/L. The method is simple and rapid, and the results of water sample determination is quite in accord with those of Gas Chromatograph.  相似文献   

8.
An improved potentiometric titration method for the determination of calcium and magnesium in sea water has been newly devised. In this method, a mini-computer is used for the automation of titrations, and ion-selective electrodes are used as an end-point detector. Calcium is determined by titration with EGTA, and total alkaline earth metals (magnesium + calcium + strontium) by titration with EDTA. Magnesium can be determined by the difference, strontium having been determined by a suitable method. In the present method, calcium and magnesium in sea water can be determined with a precision of 0.1 %.  相似文献   

9.
Selenium(Se) has been recognized as a key trace element that is associated with growth of primary producers in oceans. During March and May 2018, surface water(67 samples) was collected and measured by HG-ICP-MS to investigate the distribution and behavior of selenite [Se(IV)], selenate [Se(VI)] and dissolved organic selenides(DOSe) concentrations in the Zhujiang River Estuary(ZRE), South China Sea(SCS) and Malacca Straits(MS). It showed that Se(IV)(0.14–3.44 nmol/L) was the dominant chemical species in the ZRE, related to intensive manufacture in the watershed; while the major species shifted to DOSe(0.05–0.79 nmol/L) in the MS, associated with the wide coverage of peatland and intensive agriculture activities in the Malaysian Peninsula. The SCS was identified as the northern and southern sections(NSCS and SSCS) based on the variations of surface circulation.The insignificant variation of Se(IV) in the NSCS and SSCS was obtained in March, potentially resulting from the high chemical activity and related preferential assimilation by phytoplankton communities. Contrastively, the lower DOSe concentrations in the SSCS likely resulted from higher primary production and utilization during March. During May, the concentration of Se(IV) remained low in the NSCS and SSCS, while DOSe concentrations increased notably in the SSCS, likely due to the impact of terrestrial inputs from surface current reversal and subsequent accumulation. On a global scale, DOSe is the dominant Se species in tropical oceans, while Se(IV) and Se(VI) are major fractions in high-latitude oceans, resulting from changes in predominated phytoplankton and related biological assimilation.  相似文献   

10.
Gas-liquid chromatographic method byGehrke et al. was applied to the determination of the dissolved proteinaceous substace. Sea-water samples were evaporated in vacuum to the volume of one twentieth of the initial volume and separated from deposited inorganic salt crystals. Thirteen kinds of amino acids except histidine, arginine and cystine were quantitatively determined for artificial sea water containing sixteen standard amino acids with accuracy of about five percent and with yield of 80 to 103 percent. This method has advantage comparing with paper or thin layer chromatography on the precision and comparing with ion-exchange method on sensitivity.The difference of amino acid concentration between the sea-water samples of different depth and different region was observed. The total amounts of dissolved amino acids were found to be between 33 and 92g per liter in sea water of Pacific Ocean taken at the surface to 1,500 m in depth.Contribution No. 41, from The Research Institute of North Pacific Fisheries, Hokkaido University.  相似文献   

11.
A new method for the direct determination of reduced and oxidized Mo species (Mo (V) and Mo (VI)) in seawater was developed and used for the first time. The method includes the complexation of Mo (V) with tartrate, solid phase extraction of the Mo (V)–tartrate complex by a XAD 7HP resin, followed by elution with acidic acetone. In this study, the eluted Mo (V) was quantified by graphite furnace atomic absorption spectrometry. The detection limit of this protocol was on the order of 0.2 nM. The analytical precision was 10% of ~ 10 nM. This method was successfully applied to the determination of Mo (V) and Mo (VI) in surface and bottom waters at the head of Peconic River Estuary. Total Mo (Mo (V) + Mo (VI)) ranged from 100–120 nM in most bottom saline waters, and 2.5–15 nM for surface fresher waters. Concentrations of Mo (V) in these environments ranged from 0 nM to ~ 15 nM, accounting for 0%–15% of the total dissolved Mo pool. The time series experiments showed that the Mo speciation changed within 1 h after the water collection, and therefore it is strongly suggested that speciation analysis be carried out within the first 15 min. However, since these are the first Mo speciation data in concentration ranges typical of normal marine and coastal waters, additional research may be required to optimize the methodology and further explore Mo cycling mechanisms.  相似文献   

12.
The coprecipitation of uranium with calcium carbonate   总被引：1，自引：0，他引：1  
This report is one of the studies on the factors controlling the trace element contents of marine calcareous skeletons. The values of the distribution coefficients of UO2 2+ between solutions and carbonate precipitates were measured in the laboratory at 20±1C. From the determination of the uranium contents of marine calcareous skeletons and sea water, the values of uranium between marine calcareous skeletons and sea water are expected as 1.2 to 0.3 for aragonite and 0.2 to 0,0n for calcite. The experimentally measured value of the distribution coefficient for aragonite is thermodynamically discussed. And it was known that the value of the distribution coefficient of UO2 2+ is controlled greatly by the activity coefficient of uranium dissolved in a parent medium and the crystal form of CaCO3. The activity coefficient of uranium in solution mainly owes to the formation of complexes between UO2 2+ and CO3 2–in the solution.  相似文献   

13.
西南极海沉积硒的地球化学状态   总被引：1，自引：0，他引：1  
根据1984年11月—1985年4月首次南大洋考察所取得的样品和资料,通过萃取液萃取并利用荧光素法测定不同形态硒,对硒在南大洋沉积物中的地球化学状态进行了研究。结果表明,西南大洋表层沉积物的总硒含量为278－1168×（10-9）,其与粘土粒级有较密切的关系。硒含量的地理分布表现为海湾＞半深海＞外陆架;沉积物中硒含量不同,但其地球化学形态分配比基本相同,分别为可交换态占15％,有机结合态占36％,无机盐态占4％,晶质氧化物态占9％,矿物晶格态占37％;沉积物剖面中间隙水硒的含量变化与铁一致,在铁氧化物还原带达到峰值;可交换态硒的含量随深度的增加而升高,而晶质氧化物态的含量则随深度而降低;有机质的早期成岩分解是沉积硒参与再循环的主要来源;计算得出沉积柱表面逸入上覆海水的硒通量为3．5ng／（cm2·a）,沉积通量为13．4ng／（cm2·a）。  相似文献   

14.
Barnacles (Balanus sp) were used to examine the uptake and release of chromium-51 added to sea water in two different valence states, 51Cr(VI) and 51Cr(III).Hexavalent chromium-51 (sodium chromate) forms a true ionic solution in filtered sea water and barnacles were able to accumulate chronium in soft tissues 543 times the levels found in sea water. The experiment showed that incorporated Cr(VI), is released to the water in such way that only 20%% of maximum uptake was lost by the organisms after 26 days. Addition of the hexavalent form to non filtered sea water showed that 2% of the total radioactivity was attached to the suspended particles. Here again chromium is mainly concentrated in soft tissues, showing a concentration factor of 380 related to total chromium available in aquarium (solution + suspended particles). From the total radioactivity incorporated by the organisms, 20 % was released after 56 days in the clearance experiment.Chromium, as trivalent chromic chloride, when added to sea water precipitates and is quickly removed from the water by the filter activity of the barnacles. Unlike the hexavalent form, trivalent chromium is not concentrated in soft tissues of the barnacles and is quickly released to the water through the organisms digestive system.  相似文献   

15.
The apparent stability constants for chloride and sulfate ions with Co (II) at ionic strength of 0.67 were determined by the cation exchange method. The value of the stability constant 1 for chloride ion with Co (II) ion was 0.79±0.055. The stability constants 1, 2 and 3 for sulfate ion with Co (II) ion were 12.0±0.27, 91.5±11.4 and l,110±250, respectively. The chemical species of Co (II) in seawater was estimated at the pH of 8.0 to be present as Co2+ (63%), CoCl+ (27%) and CoSO4 0 (8.6%) using the known value of dissociation constant of Co (II), and under the assumption that only major inorganic anions are responsible for the chemical equilibrium of Co (II).  相似文献   

16.
The stability constants for sulfate, chloride and hydroxide ions with cerium (III) in the solution at ionic strength of 0.67 have been determined by cation exchange method, the values of 1 and 2 for sulfate complexes of cerium being 40±13 and 453±140, respectively and those for chloride complexes being 1.28±0.23 and 0.56±0.076, respectively. The values of 1, 2 and 3 for hydroxide complexes of cerium were (4.5±0.9)×107, (3.3±0.7)×1014 and (1.8±0.7)×1023, respectively.Using the above constants the ratios of individual chemical species of144Ce were calculated in a solution at ionic strength of 0.67 containing sulfate and chloride ions approximately the same as in seawater of 35 %. The result of calculation indicates that the dominant species of144Ce in this solution is Ce(OH)3 0 at pH 8.  相似文献   

17.
Momentum and heat flux were measured with a sonic anemometer at the Marine Observation Tower in the port of ItÔ. Under unstable conditions (T w -T a =3C4C), using the eddy correlation method, results show thatCd=(1.2±0.3)×10–3 andCh=(1.5±0.3)×10–3 at 5.5 m above mean sea level except for the case of weak winds.An unexpected relationship betweenCd and (–z/L) was observed, that is,Cd decreases as (–z/L) increases. If roughness variation over the sea is taken into account, we can explain the decrease in the range of (–z/L) less than 1, but not in the range greater than 1. This is due to a strong instability effect and the change of roughness class, from moderately rough to smooth.  相似文献   

18.
Analyses of gallium content were made by the fluorometric method on 57 samples of seaweeds which were composed of 30 species. As the result of it, the gallium content was found ranging from 0.02 to 0.64g g–1 and the average was 0.14g g–1 in the dried seaweeds.Generally, the gallium content in seaweeds had a close relationship to the aluminium and iron contents. The average weight ratio of Ga/Al was 3.8×10–4 and one of Ga/Fe was 4.0×10–4. The average Ga/Al weight ratio (3.8×10–4) was very similar to that reported for shallow-water deposits (2.1×10–4), but was definitely lower than that in sea water (1.5×10–2).  相似文献   

19.
A sea floor magnetometer for the continental shelf   总被引：1，自引：0，他引：1  
Measurement of temporal magnetic variations on the sea floor is desirable in order to extend the technique of geomagnetic depth sounding into the oceans. This paper describes a recording three-component sea floor magnetometer and its use in continental shelf depths. The orientation and tilt of the instrument on the sea floor are recorded using gelatine solutions to freeze a compass card and a ball-bearing, respectively. A backing-off procedure initially nulls the magnetic field components along each of the three mutually orthogonal fluxgate sensors. Magnetic variations along each sensor axis are then recorded within a range of ± 300 nT of these nulled positions. The resolution is ± 1 nT, and with a power drain of 800 mW the magnetometer can record continuously for 30 days. The instrument capsule is moored to surface buoys for recovery in continental shelf applications. The buoys may have marker flags, radar reflectors or radio beacons attached to them to aid in relocation.  相似文献   

20.
The heat balance of the upper ocean under a land and sea breeze was investigated based on observations of sea water temperature in the upper 300 m layer and heat flux across the sea surface at a fixed station in Sagami Bay (3510N, 13925E) during two periods of two days in August 1980 and three days in August 1981. During both periods, a typical land and sea breeze of 4–6 m sec–1 at maximum prevailed in the observation area. Large diurnal variation of sea surface temperature with a maximum peak around noon LST was observed during both periods (the daily value of the range was 0.9C and 2.5C in 1980, and 1.2C, 1.5C and 1.7C in 1981). It was found that these large temperature variations were caused by diurnal variation of the wind speed which dropped to 0–3 m sec–1 at noon when the strongest insolation (–270 Wm–2) penetrated the sea and at midnight in association with alternations of the land breeze and the sea breeze. On the other hand, vertical mixing of the sea water caused by the wind stress and/or convection due to cooling at night extended down only to the surface 10 m layer. Horizontal heat advection was negligibly small. Therefore the local time change of the heat content in the upper 10 m water column was affected mainly by the heat flux across the air-sea interface which was estimated from data on radiation fluxes measured directly on board and latent and sensible heat fluxes calculated by the aerodynamic bulk method. The water temperature below the 10 m layer also varied with time and the temperature variation in the thermocline (20–50 m depth) was frequently larger than that of the sea surface temperature. However, the variation in the upper 10 m layer was little influenced by that below the layer.  相似文献   

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