A multielement determination of major-to-trace elements in sea water was carried out by means of ICP-AES. The direct determination of the ppt level of rare earth elements in sea water is found to be difficult because of inadequate sensitivity. Therefore, their determination was made by means of ICP-AES combined with preconcentration by coprecipitation with gallium hydroxide. The analytical procedure for the determination of trace elements in sea water proceeded as follows: 15mg of Ga(III)(3 M HCl solution) was added to 1 dm³ of sea water, and the solution was adjusted to pH 9.0. After standing overnight, the precipitate was filtrated by means of membrane filter (0.45,μm) and dissolved in 10 cm³ of 3 M HN0₃. ICP-AES spectrophotometer Optima 3300-DV Perkin Elmer Japan Instrument and a U-5000AT⁺ ultrasonic nebulizer Cetac Instrument were used. RF power was 1.3 KW. The argon flow rates of the plasma gas, auxiliary gas and carrier gas were 15 dm³/min, 0.5 dm³/min and 0.9 dm³/min, respectively. The recovery of these elements by means of coprecipitation was more than 90% at pH 9.0, and the separation of these elements from major elements in sea water was also excellent. The relative standard deviation for rare earth elements determination was less than 1.95%(n=3). The relationship between the ionic potential of metal hydrate ion and the concentration of lanthanoids decreased linearly with an increase in ionic potential.

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Some man-made substances and their by-products are known for their ability to affect the endocrine systems of animals. Physiological indicators of health were determined for wild populations of the marbled sole, Pleuronectes yokohamae.Fish were obtained from three sites of the central coastal area of Miyagi prefecture: two sites in Sendai Bay, which is affected by anthropogenic pollutants, and the eastern coastal regions of Ogatsu, which receives only low levels of pollutants.
No abnormality was observed in gonad morphol ogy. Mean values for hepatic microsomal cytochrome P-450 (Cyt.P-450) content were about 0.2nmol/mg-protein. However, in a few fish from Sendai Bay the amount was more than 0.4 nmol/mg protein. These fish showed slightly lower values for brain acetylcholinesterase (AChE) and plasma total thyroxine (tT₄) in both sexes, and plasma teststerone (T) in males. A significant negative relationship between Cyt.P-450 and T levels was detected in these fish. A negative relationship between Cyt.P-450 and AChE, and between Cyt.P-450 and tT₄ was also found.
These findings suggest that (i) the health of marbled sole inhabiting Sendai Bay is going to be influenced by exposure to environmental pollutants, including endocrine disrupting chemicals, but the effects are not so severe at present, and (ii) these indicators are available as biomakers of environmental pollution by xenobiotics. Furthermore,(iii) it is advisable to investigate the relation among several indicators, including hepatic Cyt.P-450 content, T, tT₄ and AChE, as a means of assessing environmental pollution of this kind.

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The fundamental conditions for the determining selenium species (selenite, selenate, and organic selenide) in sea water using the 2, 3-diaminonaphtalene (DAN) fluorometry-HPLC method were improved. Five milliliters of a 0.1% DAN solution and 0.5ml of EDTA-NaF were added to 30 ml of filtrated sea water, and then warmed at 50°C for 20 minutes after adjusting the pH to 1. After the complex of Se (IV)-DAN was extracted with cyclohexane, and analyzed by means of HPLC with fluorescence detection. The optimum conditions for HPLC; 1) a silica gel column was used for the separation column, 2) 95:5 (v/v%) of cyclohexane and ethyl acetate as a mobile phase, and 3) detection at Ex. 375 nm/Em. 520 nm. The detection limit was 0.1 pg 1^-1 Se (S/N=2) in sea water. Selenate was reduced to selenite using 2.0 g of potassium bromide in a 1.2 M hydrochloric acid solution, and then reacted with DAN. The organic selenide in sea water was completely decomposed with nitric/perchloric acid, and did not interfere with other organic substances in terms of determination. The nitric/perchloric acid digestion was better than potassium persulfate digestion for determining organic selenide in humic substances or phytoplankton body fluid because organic matter had been completely digested.

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The {111} faces of a sodium chloride crystal appeared in the presence of citric acid when crystallized at an adjusted pH of 2.72. These new faces were never observed at the natural pH (=0.75). Dissociated species H₂C₆H₅O₇^- was suggested to be an active impurity.

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