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The toxicities of 33 metals (36 species of metal ions) in Chlorella kessleriwere investigated and compared to several parameters such as ion radii, stability constants with several ligands, solubility products, and heats of formation (enthalpy). Although a universal parameter that could explain the toxicities of all of the metal ions was not identified, the Irving–Williams series and the HSAB (hard and soft Lewis acidity and basicity) are related to the toxicity of metal ions. With regard to aluminum group elements, the amount of free ion determines the toxicity. Metal absorption was also investigated, including its time dependence (transient absorption). The absorption (adsorption) of anionic species (oxoacid) is lower than that of cationic species which in some cases shows a high collection rate of over 90%. Furthermore, absorptivity varies during the different growth regimes of the cell. Among green alga, Chlamydomonas reinhardtiiis much more resistant to metal toxicity than Chlorella kessleri. Intracellular distribution of zinc was also determined by using a zinc-fluorescent probe under a confocal laser microscope, and the result shows the intracellular distribution of pH could be an important factor for the intracellular distribution of zinc.

We examined the in vitro cytotoxic effects of an organic arsenic compound contained in seafood, viz. the trimethyl (2-hydroxyethyl)-arsonium cation, or arsenocholine (AsCho), on some murine immune effector cells, such as splenocytes, thymocytes, Peyer's patch lymphocytes, peritoneal macrophages and bone marrow (BM) cells using synthesized pure material. We found that AsCho had no cytotoxicity on most immune effector cells, even at concentrations over 10 mmol dm⁻³, and it slightly but significantly enhanced the viability of BM cells at doses over 100 µmol dm⁻³. This biological effect of AsCho on BM cells might be direct rather than due to autocrine mechanisms mediating some factors secreted by AsCho-stimulated BM cells, because the culture supernatants of BM cells pre-stimulated with AsCho did not influence the viability of other fresh BM cells. It is interesting that this unique biological effect was found in AsCho, an organic arsenic compound contained in some marine animals that are ingested daily as seafood in many countries. Copyright © 2002 John Wiley & Sons, Ltd.

We examined the in vitrocytotoxic effects of an organic arsenic compound contained in seafood, viz. the trimethyl (2‐hydroxyethyl)‐arsonium cation, or arsenocholine (AsCho), on some murine immune effector cells, such as splenocytes, thymocytes, Peyer's patch lymphocytes, peritoneal macrophages and bone marrow (BM) cells using synthesized pure material. We found that AsCho had no cytotoxicity on most immune effector cells, even at concentrations over 10 mmol dm−3, and it slightly but significantly enhanced the viability of BM cells at doses over 100 µmol dm−3. This biological effect of AsCho on BM cells might be direct rather than due to autocrine mechanisms mediating some factors secreted by AsCho‐stimulated BM cells, because the culture supernatants of BM cells pre‐stimulated with AsCho did not influence the viability of other fresh BM cells. It is interesting that this unique biological effect was found in AsCho, an organic arsenic compound contained in some marine animals that are ingested daily as seafood in many countries. Copyright © 2002 John Wiley & Sons, Ltd.

Cobalt(II and III) complexes including Vitamin B12have been investigated by X-ray photoelectron spectroscopy. Cobalt(II) and cobalt (III) complexes show the 2p1⁄2–2p3⁄2peak separation of 16.0±0.3 eV and 15.1±0.3 eV, respectively. The data of the binding energies for Co 2p1⁄2, Co 2p3⁄2, N ls and S 2p in cobalt complexes are also presented.

Thermal lensing colorimetry has been applied to the determination of nitrite ion. Color development was based on the diazo-coupling reaction among NO2−, N-(naphthyl)-ethylenediamine dihydrochloride, and sulfanylamide. The source was the chopped output of an Ar+laser operated at 514.5 nm. The beam intensity was measured with a silicon photocell of 1 mm2surface area and the resultant electrical signal was processed with a microcomputer system. The minimal detectable amount of nitrite ion using a cell of 1 cm path length is 0.2 nM.This is more than 200 times smaller than the detection limit of ordinary spectrophotometry using a commercial spectrophotometer.

The temporal variation of the partial pressure of carbon dioxide in surface seawater of Iyo Nada in the western Seto Inland Sea was measured by infrared absorption of carbon dioxide (CO2) in air equilibrated with seawater. The variation of from January to late May in 1994 was relatively small (from 270 to 340 μatm). on the contrary, the measured in September 1993 ranged from 200 to 450 μatm. It seems that the relative high observed in the north and the south of Iyo Nada in September were caused by destruction of a stratification owing to tidal currents at straits between Hiroshima Bay and Iyo Nada and Hayasui Straits, respectively. The low observed in the central Iyo Nada in September was ascribed to a tidal front where high concentrations of chlorophyll-a and a relation between and chlorophyll-a in negative sense were found. Except the observation in the north of Iyo Nada in September, the in the surface seawater of Iyo Nada were lowe than the atmospheric (about 367 μatm). The results obtained by this work and Kimotoet al. (1993) lead to the conclusion that Iyo Nada acts as a sink of the atmospheric CO2 on the average.

Progress in clean techniques that includes clean sampling, storage, treatment and analysis of seawater samples is essential for the exact determination of trace elements in seawater. Japanese marine chemists have worked vigorously to establish clean techniques and the accumulation of data. Results have met with a measured amount of success, as briefly shown in this review paper. The behavior and distribution of trace elements in seawater are dependent on multifaceted chemical, physical and biological processes occurring in the ocean. Thus, the chemical speciation of inorganic and organic species of trace elements in seawater has been eagerly studied. Specifically, the dissolved states of oxyacid elements such as Cr, I, Se, Te, As and Sb have been determined by using various procedures and methods developed by Japanese marine chemists. The present paper reviews the procedures of chemical speciation for inorganic species of Cr, I, Mn, Mo/ W, Se, Te, As and Sb as well as those for organic species of Cr, Ge, I, Se, Hg, Fe and Cu in seawater. The difficulty in obtaining exact measurements of the total concentrations of trace elements in seawater is shown concerning Fe, Cu, Zn and Se as examples.

Alkaline phosphatase activity (both dissolved and total) in Lake Kasumigaura was determined periodically together with concentrations of phosphorus compounds therein. Distinct negative correlation was found between the dissolved alkaline phosphatase activity and the orthophosphate concentration during the phosphorus-limited season. The decrease of the concentration of dissolved alkaline phosphatase was observed at the level of 1 ng ml−1of orthophosphate. The present results suggest that both alkaline phosphatase in vivo and dissolved alkaline phosphatase in the lake water play important roles in phosphorus cycles in natural water.

Laser photolysis was used to investigate the production and quenching of hydrated electrons formed after absorption of 355 nm light by dissolved organic matter (DOM) in natural waters. Correlation between the hydrated electrons generated and dissolved organic carbon in seawaters was found. The DOM in land waters ejected more hydrated electrons than seawater DOM did. Land waters contained much natural fluorescent organic matter, so the DOM in the land waters was rich in photochemically sensitive chromophores. Quenching of the hydrated electrons by the inorganic ions, nitrite, nitrate, Cd2+, Ni2+, Co2+, and [Co(NH3)6]3+were investigated by a first-order function and the Stern–Volmer model. With the former, the quenching rate constants were 10-9to 10-10dm3mol-1s-1, which was close to reported values. No regional differences were found among the seawater samples. This result suggested similar quenching mechanisms for hydrated electrons generated in the different seawaters. With the Stern–Volmer model, primary quenching was estimated. Quenching studies of land waters suggested that DOM had an aggregate nature in such waters.

Distinct negative correlation was found between the dissolved alkaline phosphatase activity and the orthophosphate concentration in Lake Kasumigaura (surface area, 171 km2) in the phosphorus-limited season. The decrease of the alkaline phosphatase activity induced by orthophosphate ions was observed at the level of 1 ng/mL of phosphorus, which is 3 orders of magnitude smaller than that in the laboratory scale experiment.

Alkaline phosphatase activity in Lake Kasumigaura was determined periodically and characterized by highperformance liquid chromatography and isoelectric focusing electrophoresis. There are two peaks in dissolved alkaline phosphatase activity; the bigger one in summer and the smaller one in winter. Molecular weight of ca. 89000 and isoelectric points 5–6 were found for most phosphatases in samples collected during the summer. A considerable part of the winter alkaline phosphatases, however, have much higher molecular weights, and major isoelectric points for these were ca. 4. These alkaline phosphatases were metalloenzymes activated by zinc. The observations above suggest that there are seasonal changes in the dominant microbial species producing dissolved alkaline phosphatase; i.e., blue-green algae, a procaryote, in summer and diatoms and flagellates, eucaryotes, in winter. The peak of alkaline phosphatase activity in lake water was predictive of a following increase in algal species therein.

Colorimetric determination of fluoride ion in drinking water was done with a long capillary cell (LCC) (length: 0.7–4 m). When a solution whose refractive index exceeds that of the cell material (Pyrex=1.474) is put into the capillary, a wave-guide(total reflection) cell is obtained, its transmissibility to source light is independent of cell shape. Color development was based on the La-ALC method: Lanthanum-alizarin complexone was added to the sample. The fluoro-lanthanum-alizarin complexone which formed was combined with N,N-diethyl-aniline and extracted into isoamyl alcohol. Fluoride complex extracted to isoamyl alcohol was mixed with a mixture of carbon disulfide and acetone (the final refractive index of analyte solution=1.57). Extension of cell length longer than 1 m provided highly sensitive colorimetry. Enhancement of absorption was 0.5–2.5×103times in magnitude by using 4 m LCC. Detection limit and recovery of this method were 10 ng/l and 93–104% (for 50 μg/l), respectively. The present method was applied to the determination of fluoride in drinking water collected around Tokyo.

The distributions of neutral atoms in the nitrous oxide–acetylene flame have been measured by nebulizing aquo ions of the following sixteen elements into the flame; cadmium, nickel, zinc, copper, lead, cobalt, manganese, iron, chromium, molybdenum, calcium, tin, gallium, indium, titanium, and boron. The distributions have been figured on the response surfaces on which the changes in distribution are expressed as functions of the flame height and the acetylene flow rate. The response surfaces for the temperature and the OH radical were also investigated. The response surfaces for the atomic absorptions of the elements can be related to the thermodynamic properties of the oxides of the elements. The results have then been used for the discussion of the atomization processes of the elements in the flame. In addition, the sensitivities of absorption spectrometry in the nitrous oxide–acetylene flame have been compared to those in the air–acetylene flame.

A method for the determination of trace zinc has been investigated using hydro-lyase activity of carbonic anhydrase. It was proved theoretically and experimentally that the activation rate of the apo-carbonic anhydrase with zinc is proportional to the amount of zinc present in the solution. Hydro-lyase activity was measured electrochemically using sodium hydrogencarbonate as a substrate. The limit of detection was 0.89 ng/ml or 40 pg of zinc, lower than that obtained by the esterase activity method. Application of the present method to the determination of zinc in real samples has been examined in order to evaluate its analytical feasibility.

Metalloenzyme (alkaline phosphatase) dissolved in lake water has been identified by means of high performance liquid chromatography (HPLC). Water samples were collected from Lake Kasumigaura in Ibaraki, and filtered with a 0.2–0.45 µm membrane filter immediately after sampling. Filtered water was concentrated to 100–2000 fold by ultrafiltration membrane which could concentrate the components of molecular weight larger than 10000. The enzymatic activity of alkaline phosphatase was measured using p-nitrophenyl dihydrogen-phosphate as a substrate. Chelating agents added to the concentrated lake water inhibited the appearance of enzymatic activity, while the enzymatic activity was recovered with addition of zinc ion. The HPLC chromatograms of the concentrated lake water were examined, where an aqueous porous gel column was used for separation. The effluent at molecular weight of ca.90000 showed specific activity of alkaline phosphatase. Zinc was also found in the same fraction. These facts suggest that alkaline phosphatase with the nature similar to procaryotes was present in the lake water.

A method for the determination of trace zinc has been investigated by using enzymatic activity of carbonic anhydrase. The recovery of enzymatic activity of apo-carbonic anhydrase was proportional to the amount of zinc in solution theoretically and experimentally, when it was monitored spectroscopically using the substrate, p-nitrophenyl acetate. The amount of zinc in the sample solutions was therefore determined from the curve, zinc concentration vs. the enzymatic activity. The limit of detection is 10 ng/ml or 2 ng. The method has been applied to the analysis of zinc in fruit juices and water samples.

For measuring the exact distribution of metal atoms in the flame, HITACHI 207 atomic absorption spectrophotometer was modified to a single light path with a smaller diameter of the light beam. Using this improved spectrophotometer, the more detailed distribution of cobalt atoms in the air-acetylene flame was measured in terms of some cobalt(III) complexes.

Thermal neutron irradiation has been carried out on the solutions of tris(acetylacetonato) cobalt(III) in benzene, ethanol, acetone and acetic acid containing various additives such as metallic salts and mineral acids. The 60Co retention in the irradiated solutions has been found to decrease sharply with the increase in the concentration of various metallic salts. This indicates that the thermal diffusive reactions which contribute greatly to the apparent retention in the irradiated solutions can be suppressed by the addition of adequate metallic salts as scavengers. Salts of the metals which can form more stable complexes with acetylacetone (i.e., Fe(III), Cu(II), Al(III), etc.) work as more effective scavengers in these systems. The upper limit for the primary retention of tris(acetylacetonato)cobalt(III) in the benzene solutions has been estimated as 0.00±0.02%. The use of adequate scavengers appears to be a useful technique to determine the primary retention in the irradiated solution systems. The 60Co retention of the solid complex irradiated at dry ice temperature was 1.4–1.5% irrespective of the organic solvents used for dissolution if they contain ferric chloride, while it increased to 2.0% in the absence of the scavenger.