Masakichi Nishimura

Complexometric titration of calcium in the presence of larger amounts of magnesium

A simple and accurate titrimetric determination of calcium in the presence of larger amounts of magnesium is proposed. Calcium is extracted into a small volume of organic solvent as its glyoxal-bis(2-hydroxyanil) complex, and the calcium is titrated with EGTA. The end-point is sharp, and occurs when the red colour of the organic layer vanishes. This method has been successfully applied to the determination of calcium in sea-water with an error less than 0.1%.

Photometric determination of zinc in meteorites

Abstract Zinc is determined in iron and silicate meteorites by the spectrophotometric dithizone method after separation from iron(III), nickel, cobalt, copper and other elements by ion exchange on Dowex I-X8 resin in hydrochloric acid solution. The distribution of zinc is so heterogenous in some irons and chondrites that 1-g samples do not give reproducible values.

Lead-210 in the Japan Sea

This is the first detailed study on the distribution of lead-210 in the Japan Sea water. The content of lead-210 ranged from 9.3±2.1 dph/l in the surface water to 3.4+-0.8 dph/l in the deep water—a quite low content as compared to that in the deep water of the North Pacific. Vertical profiles show that the content of lead-210 abruptly decreases below the seasonal thermocline (10–20 m in depth) and nearly uniform in the deep water. It is suggested that a significant amount of air-borne lead-210 deposited over the Japan Sea is transported along with the Tsushima Current to the open ocean. The budget of lead-210 is calculated by using a simple box-model and the mean residence time of lead-210 in the Japan Sea is estimated to be 15 yr.

Mercury concentration in the ocean

Seventy percent of 342 seawater samples collected in the Bering Sea, North and South Pacific, Japan Sea, East and South China Seas, and Indian Ocean had concentrations of “total” mercury ranging from 3 to 6 ng Hg l−1 with an arithmetic mean of 5.3 ng l−1 and a geometric mean of 5.0 ng l−1. In some cases, a higher concentration was observed at the surface, at the halocline or thermocline, or in the bottom water. But in general, there was no consistent correlation between mercury concentration and depth, except for a statistical tendency for mercury concentration to be slightly higher in the surface water. This tendency suggests that mercury in the ocean is supplied from the atmosphere by rain washout. The latitudinal variation of surface mercury concentrations showed that the maximum concentration at each latitude decreased from 40°N to 30°S. This variation provides evidence that atmospheric mercury is emitted mainly from continental areas naturally or anthropogenically.

Regeneration of silicate in the ocean

Regeneration of silicate in the Japan Sea, an example of semi-closed sea, was studied. In the Japan Sea Proper Water the apparent regenerative ratio of the nutrients was determined to be:ΔO ∶ΔC ∶ΔN ∶ΔP ∶ΔSi=−289 ∶(116)∶14.3∶1∶81.It was assumed that the dissolved silicate present in sea water is grouped into three fractions; 1)preformed silicate of conservative nature, 2)oxidative silicate which dissolves in oxidation process of organisms with consumption of oxygen, and 3)non-oxidative silicate which dissolves without oxygen consumption. The dissolution rate ofnon-oxidative silicate in the Japan Sea Proper Water was estimated to be 0.07μg-at. Si/l/yr from the data ofΔAOU values and assumed rates of oxygen consumption. This dissolution rate ofnon-oxidative silicate agreed with that obtained in the deep Pacific by the vertical advection diffusion model byKido andNishimura (1972).

Calcium in the Antarctic Ocean

Calcium in sea water was determined of the samples taken from the Antarctic and Indian Oceans. Surface water commonly contains less calcium relative to chlorinity than does deep water. The tendency, however, is very faint in the Antarctic Ocean. In the surface waters, the Ca/Cl ratio is lower in the tropical and subtropical waters and the ratio well correlates with phosphate. The Ca/P ratio is calculated as 37 in atomic ratio. These may indicate that calcium is uptaken by organisms to make skeletal parts from surface water which is supersaturated with respect to calcite or aragonite. On the other hand, no definite correlationship between calcium and phosphate is found in subsurface water. This fact suggests that the regeneration process of calcium from organic debris is different from that of phosphate. The increase-rate of calcium in the abyssal water is estimated to be 0.18Μg at./(1 yr), which is due to the dissolution of calcium carbonate. The rate is about a half of total carbonate increase in the water.

Effects of quaternary ammonium bases on valence-saturated but coordination-unsaturated chelates : Part I. Extraction of chelates of glyoxal bis-(2-hydroxyanil) and o-(salicylideneamino) phenol

Abstract The effects of tetradecyldimethylbenzylammonium chloride (zephiramine), a quaternary ammonium base, on chelate formation and extraction of metals were studied. By the action of zephiramine, the non-extractable 1:1 calcium- or cadmium—glyoxal bis-(2-hydroxyanil) chelate changes to an extractable uncharged chelate, Ca(A)(H 2 A) or Cd(A)(H 2 A), by replacing water molecules with GHA molecules (H 2 A). This is a new type of synergism. In the presence of zephiramine, the non-extractable 1:1 zinc or nickel- o -(salicylideneamino) phenol chelate also changes to a negatively charged Zn(L) 2 2- or Ni(L) 2 2- chelate which can be extracted by coupling with two molecules of zephiramine.

Effects of quaternary ammonium bases on valence-saturated but coordination-unsaturated chelates: Part II. Extraction of magnesium 8-hydroxyquinolinate

Abstract It is known that 8-hydroxyquinoline (HQ) forms a non-extractable chelate with magnesium, Mg(Q)2·2H2O, and in the presence of pyridine an extractable chelate, Mg(Q)2(pyridine). In these systems, the presence of a quaternary ammonium base, zephiramine, changes both the oxine chelates to the Mg(Q)3(zeph) chelate which is extractable into inactive solvents. Zephiramine has the effect of expelling coordinated water or the pyridine molecule from a chelate to form a highly coordinated chelate with respect to the ligand.

Effects of quaternary ammonium bases on valence-saturated but coordination-unsaturated chelates: Part IV. Extraction of some divalent metal 8-hydroxyquinolinates

Abstract The effect of zephiramine on the chelate formation and extraction of some divalent metals with oxine is reported. In the presence of zephiramine, the non-extractable 1:2 zinc— and cadmium—oxine chelates as well as the extractable 1:2 nickel— and manganese—oxine chelates become highly coordinated ternary complexes, M(Q)3 (zeph), which are easily extracted into 1,2-dichloroethane. Copper is easily extracted into 1,2-dichloroethane as Cu(Q)2, which is not affected by zephiramine.

Silica in the sea — its forms and dissolution rate

Abstract Reactive, particulate, and total silica were investigated in seawater samples collected in the Oyashio and Kuroshio areas of the western North Pacific and Funka Bay near Hokkaido Island. The concentrations of particulate silica and suspended inorganic matter in the Japan Sea were also determined. A vertical diffusion model was first applied to the profiles of particulate silica to estimate the rate of dissolution of particulate silica in the intermediate water of the Japan Sea. The dissolution rate, which corresponds to the rate of increase of reactive silica, was estimated to be 0·04–0·4 μg-atoms Si 1−1 γr−1, providing the vertical eddy diffusivity is 1–10 cm2 s−1 and the settling velocity of particulate matter is (1·16–11·6) × 10−4 cm s−1. Reactive silica is the dominant species of silica in seawater. No colloidal silica is detectable in samples taken either near shore or in open seas, in any of the whole water column from the surface to near the deep-sea bed. Particulate silica concentrations varied from 0·1 to 2·0 μM Si in the open seas and from 0·5 to 11 μM Si in Funka Bay. Higher values were observed in the surface and subsurface waters in the Oyashio area and the bottom waters in the coastal region.