Very stable halocarbons such as chlorofluorocarbons (CFCs) and carbon tetrachloride are responsible for both the stratospheric ozone depletion and the global warming as they accumulate in the atmosphere. Background atmospheric concentrations of CFCs and other halocarbons have been determined accurately and precisely at surface level both in the northern hemisphere (Hokkaido) and in the southern hemisphere (Antarctica). The atmospheric concentrations of CFC-11 and CFC-12 have been increasing by 4% a year since 1979; the CFC-113 concentration tends to increase much faster (10-20% a year). Vertical profiles of major CFCs upio the stratosphere as determined in balloon experiments (grab-sampling and cryogenic sampling) over Japan reflect their behaviors in the stratospheric UV photolysis.

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Air samples were collected on board at intervals of about 5° in latitude between Tokyo and Syowa Station late in 1987 and 1988, and methane was measured by a GC-FID method. South of the intertropical convergence zone (ITCZ), mixing ratios were al most constant through Syowa Station. Their mean values and standard deviations were 1.578 and 0.008 ppm in 1984, 1.611 and 0.012 ppm in 1987, and 1.628 and 0.008 ppm in 1988. The average increase rate of these mean values was 0.013 ppm/y from 1984 to 1988. On the north of ITCZ, mixing ratios in 1987 were higher than those of 1988 against the increasing trend observed south of ITCZ. This can be explained by the meteorological conditions when air samples were collected.

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A method is described for the preconcentration and determi nation of vanadium(V) ion in aqueous solutions. A 100 ml of sample solution containing vanadium(V) was mixed with 50mg of activated carbon (to be hereafter abbreviated as AC) under stirring for 30min.The solution was then filtered orcentrifuged and the concentrations of vanadium(V) in the filterate or supernatant solution were determined by a graphite furnace AAS. The optimum pH valuesfor the adsorption were 4.O-5.O. It was found that the adsorption amounts increased greatly by the addition of 8-quinolinol (oxine) to the sample solutions. The adsorption percentage was measured for a concentration range of 0.5-80 ppm of the vanadium(V) by 50 mg of AC in 100 ml of solution. The maximum adsorption amounts were determined to be 16 and 34 mg g^-1 without and with the oxine of 2.5 mg, respectively. It was also found that the oxine of 8.7 mg (i. e., 87% of oxine added) was adsorbed on the AC surface when the solution containin g 10 mg of oxine with 50 mg of AC was stirred for 30 min; such an AC is abbreviated as AC(0x). When the sample solution was filtered through a small filter paper coated with the AC (0x) of 58.7 mg, the maximum adsorption amounts of vanadium(V) increased to 55 mg g^-1, in which the molar ratio of Ox to vanadium was 1: 1. The adsorption percentage of V on the AC (Ox)was little affected by the coexisting salts such as NaCl, CaCl₂, Zn(NO₃)₂⋅6H₂O, and CH₃COONa, where each salt was added up to 10 g per 100 ml of the sample solution, while decreased with increasing amounts of Cu(NO₃)₂⋅3 H₂O, Na₂C₂O₄, and Na₂[H₂edta]⋅2H₂O. After vanadium(V)in the sample solution was once adsorbed on the AC (Ox), vanadium ( V ) was easily desorbed from the AC(Ox) by the addition of HC1 of 1 mol dm-3. When a 200 ml of real sample was concentrated finally to 1 nil by the above adsorption- desorption procedures, the detection limit for vanadium(V) was 0.045 ng ml^-1. For 15 samples of each natural water, vanadium(V) concentrations for tap water and river water were determined to be 1.2 (R. S. D. =24%) and 2.9 (R. S. D..10%) ng ml^-1, respectively.

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In order to study the distribution and fate, of butyltin compounds in the marine environment, the concentrations of dibutyltin dichloride (DBTC), tributyltin chloride (TBTC) and tetrabutyltin (TetBT) in seawater collected from several bays were measured. DBTC, TBTC and TetBT at ng/l (ppt) levels in seawater were determined by gas chromatography with flame photometric detection (GC-FPD). DBT and TBT compounds in seawater were hydrogenated to dibutyltin dihydride (DBTH) and tributyltin hydride (TBTH) with sodium borohydride, and simultaneously extracted into dichloromethane. The extract was dried with anhydrous sodium sulfate, and was concentrated to 1 ml on a rotary evaporator at 40°C. The recoveries of DBTC and TBTC added to seawater sample were 87.1-98.4%. The detection limits of DBTC and TBTC using 1000 ml of seawater were 0.01 μg/l and 0.01 μg/l (10 ppt), respectively. Seawater samples (n=62) were collected from Hiroshima Bay (A), Maizuru Bay (B), Murotsu Harbor (C), and Kudamatsu Bay (D) during the period from April 1989 to November 1989 and the distribution of DBTC, TBTC and TetBT in seawater were investigated. The results obtained were as follows:
1) The concentrations of butyltin co mpounds in seawater were found to be in the range of N. D. (not detected)-0.40 μg/l for DBTC, N. D. -0.58 μg/L for TBTC and N. D. for TetBT.
2) Frequent concentrations of DBTC and TBTC in seawater were in the rang e of 0.010.05 jugg and 0.01-0.05 respectively.
3) DBT compound in sea water could be produced by degradation of TBT compound in the marine environmet.
4) The concentrations of DBTC and TBTC for Murotsu Harbour (C) were higher than those for Hiroshima Bay (A), Maizuru Bay (B) and Kudamatsu Bay (D). Thus, DBT and TBT compounds were not accumulated in big bays, but in little harbour with relatively poor water exchange.

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This method is based on the direct heating of activated carbon (AC) collected selenium(IV)-3-phenyl-5-mercapto-1, 3, 4-thiadiazole-2(3H)-thione (Bismuthiol II) complex: that is, AC is introduced directly as "AC-suspension" into the graphite tube atomizer, without the desorption of seienium from AC. For the determination of selenium(IV), conc. hydrochloric acid is added to the sample solution containing less than 0.5 μg of selenium (IV) at a final concentration of 1.5 M, and then, 5 cm³ of 0.1% Bismutiol II solution is added, and the solution is stirred for 5min. for formation of complex. Further, 50 mg of AC is added and one is stirred for 5 min. for the collection of complex. After separation of AC from the aqueous phase through a membrane filter, An AC-suspension is prepared by adding 5.0 cm3 of water to the AC.10 μ1 of Rh solution (500 μg Rh/cm³) is injected into the graphite tube and is previously heated. Then, aliquots (10 μl) of AC-suspension is injected into the graphite tube and selenium peak height is measured under the optical instrumental operating conditions. Selenium(VI) is collected by same procedure after reduction to selenium (IV) by potassium bromide in the presence of hydrochloric acid. The determination limit was 0.02 μg/1000 cm³ (S/N=-3), and relative standard deviation (0.25 μg/100 cm³) was 3-4% (n=6). This method was applied to the determination of selenium(IV) and selenium(VI) in well water and rain water.

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A simple and rapid preconcentration method for the determination of sub parts per billion amounts of chromium(III) and chromium(VI) in natural waters is described. The proposed method is based on the extraction with 0.1 ml of solvent in a centrifuge tube, and a preconcentration factor of 50 times is obtainable using 5 ml of filtered sample. The optimum preconcentration conditions were examined. Chromium(VI) was quantitatively extracted as 1-pyrrolidinecarbodithioate at pH 3.5 in 1, 2-dichlorobenzene, and determined by graphite furnace atomic absorption spectrometry using a pyrolytic graphite coated tube. Chromium(III) could be extracted, as chromium(VI), after oxidation by cerium(IV). The chromium(III) concentration was obtained by subtracting the chromium (VI) concentration from the total chromium [chromium= + chromium(VI)] concentration. To release the bound chromium from colloids and organic complexes, the powerful digestion was required. Therefore, the inorganic and easily extractable chromium species were determined by the proposed method. The lower limit of determination (10 a) was found to be 0.012 ng/ml of chromium(VI) in the initial solution. Relative standard deviations for chromium (VI) ranged from 4.0% (n=4) to 12.5% (n=3) in river water, from 3.4% (n=5) to 11.0% (n=6) in sea water. The ratio of chromium (VI) to total chromium in sea water was higher than that in river water. The losses of chromium species at natural pH of filtered sample stored in glass and polyethylene bottles have been investigated. As a result, it is confirmed that filtered sample should be collected in glass bottle, stored in refrigerator (ca.2 °C), and analysed within 5 days.

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The new preconcentration method of As(III) and As(V) with hydrous lead(IV) oxide (HLD)was developed. The adsorption curves of As(III) and As(V) on HLD in the pH range lower than 6 were very similar and the adsorption capacities of HLD for As(III) and As(V) at pH 3 were found to be about 1×10^-2 mol per mol of HLD. The adsorption mechanism of As(V) on HLD was the simple anionic adsorption type, while in the case of As(III), it was found that As(III) was oxidized to As(V) by HLD and then adsorbed on it. They could not be determined separately, however, HLD was considered to be useful to concentrate trace amounts of As(III) and As(V) in water sample solutions. Then the new recommended method for determination of arsenic in artificial river waters was developed as follows: The trace amounts of arsenic in a sample solution adjusted to a pH value of 2 was collected on HLD by shaking with it or passing through it loaded on a membrane filter. The HLD was filtrated off, and dissolved with EDTA solution. After Pb(II), produced from HLD, was removed from the solution with the Dowex 50 W resin, arsenic was determined by spectrophotometry using ammonium molybdate-Marachite- Green reagent. As the results, 0.1-10pg of arsenic was determined with good recovery. The presence of diverse ions added in the artificial river water samples had no significant influence on the preconcentration and determination of arsenic. The detection limit of arsenic in the artificial river water samples was determined to be 0.05 ppb.

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A preseparation procedure has been developed for analyses of organic compounds in atmospheric aerosol by gas chromatography/mass spectrometry (GC/MS). Organic compounds were fractionated into discrete seven compound classes (alkylcyclohexanes, normal alkanes, fused aromatic hydro-carbons, ketones and esters, alchols, phthalic acid esters, and carboxylic acids) by adsorption column chromatography with Florisil. To separate and recover the six compound classes but carboxylic acids, the column was eluted successively with 50 ml of isooctane, 50 ml of hexane, 50 ml of 5% diethyl ether in hexane, 100 ml of 20% diethyl ether in hexane, and 25 ml of 5%methyl acetate in hexane. Carboxylic acids were esterified with a mixture of 1M HCl/methanol and methyl acetate in the column, and then they were eluted as the methyl esters. In the separation and recovery tests, each compound class was completely separa ted within a single fraction except part of the phthalic acid esters was eluted in the alcohol fraction. The recoveries in the procedure were more than 80% for all the compound classes. When applying this preseparation to an aerosol sample, about 60 organic compounds were systematically identified in the fractions by GC/MS.

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Recently, it has been significant that the sulfur isotopic composition of biological samples reflects their living environment. A rapid method for the determination of the sulfur isotopic ratio (³²S/³⁴S) in biological samples was investigated by means of secondary ion mass spectro metry (SIMS). A human nail sample of 50-100 mg is ignited in a Parr 1108 oxygen com bustion bomb filled with oxygen to 30 atm and added with 1 cm³ of water. The sulfur trioxide formed dissolves in water as 5O₄^2- to which one drop of 1 M (mol⋅dm^-3) hydrochl oric acid and 5 cm³ of 10% barium chloride solution are added to form barium sulfate. The dried barium sulfate is then heated with 20 cm³ of tin(II)-strong phosphoric acid at 280°C for 20min under a flow of nitrogen. The hydrogen sulfide formed is absorbed in a zinc acetate solution to fix as the zinc sulfide which is in turn converted to silver sulfide by adding 10 cm³ of O.1 M silver nitrate solution. Fifteen milligrams of the silver sulfide is ground and pressed into a thin film. A pair of thin films of silver sulfide, the sample to test and the standard, is set in the same hole of a sample holder. The sulfur isotopic ratio of the standard silver sulfide was deteremined by the mass spectrometric (MS) method reported previously. The ³²S/³⁴S ratio determined was 22.300 which was based on the value (³²s/³⁴S=22.220) of the international standard, Canyon Diablo troilite. Cs⁺ is used as a primary ion and the emitted ³²S^- and ³⁴S^- secondary ions are measured. Analyses are performed under computer c ontrol. Typical operating conditions are as follows: The accelerating potential, beam current and beam diameter of the primary ion are 10 kV, 0.1-0.5 μA and 165 μm, respectively, The sulfur isotopic ratio of samples measured by SIMS is corrected against that of the standard silver sulfide. RelativestandarddeviationswereO.39, 0.17 and 0.47% for the sulfur isotopic ratio(³²S/³⁴S)of 21.986 (cystine), 22.281(methionine) and 22.026 (nail), respectivdy. The δ³⁴S permil values of cystine, methionine and a kind of human nail were +10.64, -2.74 and +8.81‰.

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A simple measurement method with the molecular diffusion sampler using porous PTFE tube to measure nitrogen dioxide (NO₂) concentration in the atmosphere was examined. The porous PTFE tube (length: 8 cm, outside diameter: 8 mm, inside diameter: 6 mm, pore size: 1.0 pm, porosity 85%) used in this study was small but had large diffusion area. The method was as follows: a molecular diffusion sampler which was enclosed a collection liquid (30% triethanolamine-GO% dimethyl sulfoxide-10% ethylene glycol) in the porous PTFE tube was exposed in the exposed chamber and the atmosphere. And then, NO₂^- in an aqueous extract of the collection liquid of the sampler was analyzed with an ion chromatograph. According to the chamber experiment, the influence of meteorological factors (temperature, relative humidity and wind velocity) on this sampler was examined. As to the temperature, the amount of collection of NO₂^-, with sampler was caused 18% increase owing to 10°C rise of temperature for measurement of ₂^-. On the other hand, the influence of relative humidity was not noticed. And the increase of wind velocity 1 m/s was caused only 3% increase of amount of collection. But in the actual applications the influence of wind velocity was almost neglected. It bec ame evidence that the sampler employed in this study was small and light and the extraction procedure was easy since the collection liquid was used and moreover the deteimina tion was rapid by the use of ion chromatograph. And yet, this method was recognized to be a high sensitive measurement (minimum amount of exposure: 12 ppb⋅h) that was enou measure NO₂ concentration in general atmosphere and room atmosphere even in a pe riogdh otof only an hour level in spite of molecular diffusion sampler. Hence, it was thought that this sampler was most adap t to use as a short term sampl er f or one day level and personal sampler of NO₂ measurement in the case of considerati on of the NO₂ concentration in the atmosphere.

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Artifact N₂O formation was investigated, to find a su itable N₂O grab sampling system for flue gases from combustion sources. Stainless steel canister was the best storage vessel for the flue gases, based on the stability of samples, but, in short-time storage, poly (vinyl fluoride) film-bag was useful as well as the canister. Gas mixture of 200 ppm NO, 800 ppm SO₂ and 16.5 mmHg⋅H₂O was reacted at atmospheric pressure and room temperature, to fo rm 40 ppm N₂O in only three hours storage. The N₂O formation was eliminated effectively by use of the sampling system (ice trap→soda lime column→ice trap→CaCl₂ column), and 51ppm N₂O, as net value, was obtained from fluidized bed boiler flue by the sampling system.

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The distribution and chemical form of lead in vegetative organs of Athyrium yokoscense (Fr. et Say. ) growing in the polluted areas resulting from lead tiles of the ruins of Kanazawa Castle, now on the campus of Kanawaza University have been investigated. The content of lead (by dry weight) in tissues of this fern species increases in the order of spores (-81 ppm) <sporangium (-740 ppm) <leaf blade (-2080 ppm) >petiol (-1530 ppm) <rhiz ome (-2890 ppm) croot(-22400 ppm). It was also found that the roots of this fern acc umulated a large amount of lead over the cell walls of cortex, while in the case of the petiol and leaf blade of the fern, lead w-as distributed over the cell walls of sieve tube of most of the stele. The content of lead (by dry weight) in the section of the fern roots increases in the order of stele (with endodermis, 3340 ppm) <cortex (with inner cortex, 12900 ppm) <<epidermis (with outer cortex, 18000 ppm). The accumulation of lead and its tolerance have some correlation with the concentration of sulfur in the tissues of this fern and its associated growing soils. The content of amino acids (by dry weight) in stele (with xylem and pholoem, 114 nmol/mg) is higher about two point fivefold than that in cortex and epidermis (45 nmol/mg). On the basis of these findings, main chemical species of lead in the tissues of Athyrium yokoscense are considered to be lead sulfate (cortex and epidermis parts) and metal complexes with pectic acid and some amino acids (stele part).

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A short-term system to detect enviromental mutagens is presented by using a plasmid (pSK 1002) carring a fused gene umuC-lacZ introduced into Salmonella typhimurium TA 1535. The principle of this test is that when mutagens in sample attack the DNA in the tester strain, β-galactosidase is produced in propotion to the amount of the mutagens and then reacts with o-nitrophenyl-β-^D-galactopyranoside (ONPG) to produce o-nitrophenol which can be detected at 420 nm. This method showed 12 times higher sensitivity than the previous method when AF-2 was used as test compound, and major improvements made by us are as follows; ( 1 ) in order to determine the amount of produced enzyme, the volume of culture treated with the test compound was increased from 0.25 ml to 1.0 ml, ( 2 ) the poly(oxyethylene)(23)dodecyl ether and toluene were selected as loosening reagents of the cell membrane, and ( 3 ) one ml of ONPG (4 mg⋅l^-1) and 45 min of reaction time were adopted. This method was applied to mutangenicity test of river waters to which clorine and chlorine-alternative disinfectants such as, chloramine, chlorine dioxide, and ozone were added.

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Chromium(VI) anions (chromates, dichromates) react with lead acetate in an acetic acid solution to form a yellow precipitate of lead chromate. To a 100 cm³ of a sample solution containing less than 500 μg of chromium(VI), 1cm³ of acetic acid and 1cm³ of 5% lead acetate solution were added at 5°C. The solution was stirred for 10 min and filtered through a O.2pm membrane filter paper. The precipitate on the paper was subjected to the X-ray fluorescence spectrometry. The calibration curve gave a curved line in the region of 50-500 μg of chromium (1/1), but a straight line in 1-50 μg only for the direct addition of O.5 g of a crys talline lead acetate.

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A sensitive flow injection method for the determination of hydrogen peroxide using titanium (IV)-4-(2-pyridylazo)resorcinol (denoted as Ti-PAR) reagent was described. The Ti-PAR reagent reacts with hydrogen peroxide to form Ti(IV)-PAR-H₂O₂ complex exhibiting the absorption maximum at 508 nm. The linear response was obtained in the range of 1.36-1360ppb of hydrogen peroxide for a 100 μl sample. The method was applied in dealing with 40samples per hour, and the results were accurate with the relative standard deviation of 0.8% for the injection of 34 ppb hydrogen peroxide (n=10). The contents of hydrogen peroxide in rainwater collected in Tokyo area were obtained by this method with satisfactory results.

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Chromiym(VI) in fresh concrete samples has been tested qualitatively by a diphenylcarbazide method, a barium chromate method, and a perchromate method. Chromium(VI) was separated from sulfate by precipitating silver chromate since, for ion chromatography, large amount of sulfate ion interfere. The silver chromate thus obtained was dissolved in ammoniacal solution. Ion chromatography was carried out under the condition: eluent, 1 mM potassium hydorogen phthalate/10% acetonitrile (pH 7.10) flow rate, 1.2 m//min. Chromium(VI) was also estimated spectrophotometrically by a direct colorimetry of the yellow chromate ion, or by a more sensitive method involving a reaction between the dichromate and diphenylcarbazide. Analysed samples contained between 2-12 mg of chromium (VI) per kg of cement.

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The chemical states of iron in airborne particles collected by the Andersen sampler have been investigated by Mossbauer technique to find an indicator effective to estimate contribution of human activities which can be derived merely from measurements at room temperature. The fine particles (<1.1 μm), known to be emitted from combustion processes, have smaller Fe²⁺/Fe³⁺ ratios than the coarse particles (>7.0 μm) in all sampling sites. Fe²⁺/Fe³⁺ ratios of the samples collected from the urban area are smaller than those from the suburban area in every particle size. These facts suggest that the Fe²⁺/Fe³⁺ ratio can be an indicator of anthropogenic contribution.

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Secondary ion mass spectrometer, X-ray microanalyzer and scanning electron microscope have been used to investigate the surface characteristics and depth profile of coal fly ash. Coal fly ash particles were size-fractionated, magnetically separated, and mounted in the indium metal sample holder (6 mm diam., 2 mm thickness). Large particles (ca.100 μm diam. )were analyzed to facilitate both particle handling and the characterization of individual particles using surface microprobe techniques. Results on ion microprobe depth profiles and X-ray image of elements on sputtered surfaces of fly ash particle show fairly good agreement.

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Sulfur compounds (methane sulfonic acid (MSA), SO2 and non sea salt sulfate (nss-SO 4^2-)) in the marine atmosphere were investigated at the cource of the Antarctic Exploration ship "Shirase" over the North Pa cific Ocean, the Indian Ocean and the Anlarctic Ocean at Oahu Island over the North Pacific Ocean and at Bermuda Island over the North Atlantic Ocean. In any marine atmosphere, an existence of MSA was confirmed. Therefore, it was found that dimethyl sulfide (DMS) as a precursor of MSA was emitted globally from sea water to atmosphere. Moreover, a high concentration of MSA in Bermuda was observed during early summer when marine phytoplankton propagated. It suggestes that MSA is biogenic product. From this work, the mean concentrations in the unpolluted open sea atmosphere were 0.03μg/m³ for MSA, 0.4μg/m³ for nss-SO₄^2- (non seasalt sulfate), 0.05 ppb for SO₂. On th e base of these measured concentrations, the global emission of biogenic sulfur compounds from sea water to atmosphere is estimated to be about 50 TgS/y. This value is comparable to 40%of the sulfur emission (126 x 10¹² gS/y) from anthropogenic sources.

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Nitrogen stable isotope ratios (δ¹⁵N) of N₂O in ground waters were determined by mass spectrometry to elucidate those source mechanisms: nitrification and denitrification. The concentrations of N₂O in ground waters were two to three orders of magnitude higher than that under atmospheric equilibrium (Table 2). The δ¹⁵N values of N₂O, in the range between -32 and +3‰, were significantly lower than those reported for NO₃- in various ground waters (Fig.2). It is known that N₂O produced through nitrification is highly depleted in ¹⁵N than NH₄+. In the light of evidence that the NO₃- in ground water gives a similar δ¹⁵N value to that of the reactant nitrogen, the present findings can be explained by considering nitrification as a major producing mechanism for groundwater N₂O. The range of N₂O/NO₃- ratio in groundwater from 0.1 x10^-3 to 9.1 x10^-3 was equivalent to those reported for nitrification (Fig.1), supporting this view. The ¹⁵N-depleted N₂O is also produced from the initial stage of denitrification. Since the magnitude of kinetic isotope fractionation of nitrogen during production of N₂O (NO₃-→N₂O)is nearly equal to that during its reduction (N₂O→N₂), the δ¹⁵N value of N₂O becomes close to that of NO₃- when a steady state is established. From the chemical properties of groundwaters (Table 2), it was possible to suppose that denitrification occurred at the site, which. can provide an anaerobic condition with much organic matter, such as inside of soil aggregates. If so, δ¹⁵N values of N₂O should be close to those of NO₃-, because the denitrification must be in a steady state, where the activity is determined by the supply of NO₃-. However, against this expectation, N₂O was more depleted than NO₃- in ¹⁵N at the groundwaters. Accordingly, it may not be unreasonable to consider that a large portion of N₂O in groundwater was derived from nitrification.

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The seasonal variation and regional features of source contributions to atmospheric particles aerosol in Toyama Prefecture (Takaoka, Toyama, and Kurobe areas) were investigated by a Chemical Mass Balance (CMB) method. Source contribution of total susp ended particles were as follows: soil ; 12-69%, secondary particles ; 11-42%, diesel automobile ; 5.9-28%, sea salt ; 0.9-17%. Each contribution of iron and steel industry, refuse incineration, fuel oil combustion and gasoline automobile was negligible respectively. The contribution of sea salt was 3.4-5.6% in spring and summer, 9.2-9.4% in autumn and winter, which suggested that sea salt were transported b y winter monsoon in autumn and winter. The predominant sources were demonstrated that soil and sea salt for giant and coarse particles (>2 μm), and diesel automobile and secondary particles for fine paricles (<2 μm).

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The influence of atmospheric pollutants on the environmental have many mechanisms which are not yet elucidated. In this stud y, nitrate and sulfate ions in soils, rain precipitation, and nitrogen dioxide and sulfur dioxide in the atmosphere were measured for two months as indications of the influence of air pollutants on soils. The results clearly showed mechanisms of the direct sorption of atmospheric pollutants into the soil and the washing of absorbed pollutants in the soil by rain. Dry soil was found to absorb more air pollutant than did wet soil. It has been. claimed that the forest damage caused by the air pollutants or acid rain in Japan is less than in Europe and America, presumably because Japanese weather has a lot of rain.

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In the past about 20 years from 1952 to 1974, about 880000 t ons of mercury pesticides (average mercury content 0.27%) had been sprayed on paddyfields in all over the country of Japan. Considering the mercury behavior in the atmosphere, it is important to evaluate the influences of mercury emitted to the atmosphere from paddyfields. But the effects of residual mercury on air pollution have not been inspected chemically. In this paper, based on the measuring data of me rcury in soils of paddyfields, authors tried to elucidate the behavior of residual mercury in soils and mercury pollution. This may provide background informations on mercury in paddyfields at the time to estimate the addition from outside mercury sources in the future. 203 soil samples were collected from Niigata city and 8 districts in northwest of Niigata Prefecture, Japan. The soil samples were analyzed for total mercury using flameless atomic absorption spectrophotometer with a combustion-gold trapping-heat vaporization procedure. As a result, the mercury contents were ranged from 0.012 to 0.66 ppm with a mean O.15 ppm based on dry weight. This value was 2-3 times as large as that of soils in uncultivated land. And, though it was found the mercury in pesticides was more unvolatile than expected, the air pollution by vaporization of pesticide mercury in soils of paddyfields was confirmed. The amount of mercury released to the atmosphere from the residual mercury o f pesticide in soil could be estimated as about 29 tons/y. This value corresponds to about 20% of the total mercury emmision in air from natural sources and man's activities.

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Concentrations of major dissolved components, pH values, temperatures etc. of river waters of the Osozawa river water system, Gunma, have been measured anuually since 1975 in order to investigate the influence upon them of the wastewaters from the Shirane sulfur mine. The Shirane mine, which had been one of the major sulfur mines in the Kusatsu-shirane volcano area but was closed in 1973, still discharges wastewaters from its disused pits. The wastewaters, which, unlike hot spring waters in the same area, most probably are not directly affected by volcanic activity of Mt. Kusatsu-shirane, are strongly acidic (pH=1.68-1.84) and are rich in sulfate ion, iron and aluminium. River waters of the Osozawa riv er water system are originally of good quality and nearly neutral, but are turned bad in quality by the influx of the wastewaters from the Shirane mine. Although the influence of the wastewaters gradually decreases downstream, it reaches even the Agatsuma river, about 9 km down from the influxing point of the wastewaters; For instance, pH values of the river waters influenced by the wastewaters are kept below 3in the whole Osozawa river water system. Secular changes of sulfate ion an d iron concentrations and pH of the river waters from 1975 to 1989 indicate that it is less likely that the bad influence from the wastewaters will be intensified in the future. Judging from the present status and the secular changes of the influence, however, it will be necessary to keep watching water quality of the Osozawa river water system closely.

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Monthly samping of the surface water was done at 3 points in Lake Teganuma and at the three rivers flowing into the lake, from Dec., 1988 to Dec, 1989. The concentrations of soluble inorganic chemical species were determined by ion-chromatography, ion electrode, atomic absorption and emission spectrometry and inductively coupled plasma emission spectrometry. The results were analyzed statistically using the principal component analysis, in order to know the source of the anthropogenic pollutants which made the lake one of the most polluted in Japan (by the COD value). The pollutant such as phosphate and ammonium ions were found to enter mainly from the two rivers, River 0-hori and River Ohtsu. The population on the catchment of them were known to be high. These species which showed high seasonal variation and the variation between stations were supposed to be highly influenced by human activity. On the other hand, the concentrations of sulfate, sodium, chloride, calcium, strontium were found to show little variation with the respect of season nor of the stations. The concentration of trace elements such as iron, manganese and zinc always showed higher values in the river than in the lake water, while that of vanadium was higher in the lake. This fact might show that the high pH value of the lake (9.2-9.5) was the main factor in deciding chemical form of these elements in the lake. Discussions were done comparing the data with those of other researchers.

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The copper plates were exposed to ambient atmosphere at different locations under various environmental conditions. The plates were analyzed by FT-IR reflection absorption spectroscopy. The spectra of these plates were classified into 4 patterns according to their sampling locations : seaside, urban, rural and mountainous. FT-IR analysis showed that the plates from most of 26 locations in the delta of Yoshino River were corroded by reaction with sea spray. This result revealed that sea spray is transported to the middle course of Yoshino River. The formation of sulfato, nitrato and hydroxo species as well as oxides (Cu₂O and CuO) was observed on the surface of the corroded plates. The formation of sulfato species is mainly attributable to sea spray. Of several metals examined, copper was found to be most suitable for monitoring corrosive pollutants in the atmosphere with its reflectivity and reactivity.

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Environmental pollution by pesticides became a major issue. In this study, the environmental fate of representative organochlorine pesticides were predicted to evaluate their environmental safety by a kinetic model from physicochemical parameters such as air-water partition coefficient and adsorption constant to soil and biological parameters such as aerobic biodegradation rate constant. The subject area of prediction is Tokyo metropolis, surrounding three prefectures and Tokyo Bay. The average concentrations at steady state in the case of continuous loading of ten pesticides and the concentration time profiles of two herbicides in the case of momentary loading were predicted. The results obtained were as follows; ( 1 ) Soil compartment tends to be a major polluted compartment in the case of continuous loading for many pesticides. Air is also a major polluted compartment for chloropicrin, dichlorvos and DCIP whose air-water partition coefficients are relatively high, and water is a major p lluted compartment for trichlorfon, dichlorvos and DCIP whose adsorption constants to soil are relatively low. ( 2 ) Although sediment is not a major polluted compartment, the concentrations of several pesticides and their biodegraded intermediates in sediment are predicted to be high. ( 3 ) On the time profiles of chlornitrofen and thiobencarb in the case of momentary loading, the concentrations in soil ar e calculated to be decreased according to the first-order rate equation, whereas those in water are calculated to be increased for 10-30 days after loading and are decreased slowly. ( 4 )Estimation of man intakes of pesticides showed that the levels of intakes were not serious for the relatively large area such as Tokyo area, and it was considered that the pollution in small area should be directed attention.

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Atmospheric deposition samples were collected biweekly from April 1989 to June 1990 at coast of the Japan Sea in Tsuruoka. The samples were analyzed for Si, Na and SO₄^2-. The deposition rate of particulate-Si showed spring peak as well as that of the atmospheric concentration. The annual deposition rate of aluminosilicate at the station was 12 g m^-2 y^-1. This value was one order of magnitude larger than that in the central North Pacific region. The atmospheric annual deposition rate of SO₄^2- was 16.1 g m^-2 y^-1 and 25% of this value was nonsea salt fraction. This deposition rate of nonsea salt SO₄^2- in winter (Nov. -Mar. ) was larger than that in other seasons. A large part of this nonsea salt SO₄^2- may be originate in air pollution of northern hemisphere.

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The process of weathering is simulated as the reaction between minerals and aqueous solution by Helgeson (1969). This study showed that geochemical simulation is successfully applied to the evaluation of several physical properties of weathered products during rock weathering. The changes in grams of chemical species/1000 g of solution and the degree of saturation of secondary minerals, shown in Fig.1, are calculated for the increments of reaction progress (ξ) in the hydrolysis of granite as an example. The formation of saturated mineral zoning by weathering is illustrated as the area of 10 cm² in profile (Fig.2). The methods of evaluation of the several physical properties are shown by simple equations in each e of ideal profile. The changes in mineralogical and chemical properties are correlated with the changes in physical properties. The calculated trends do not show monotonous increase or decrease in physical parameters (Fig.3). The nature of chemical reactions as well as the migration of permeating water and physical properties of products must be considered in the simulation of weathering.

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Mercury concentration in soil was monitored in downtown Tokyo through April 1985 to February 1986 on the basis of once a month sampling. An analytical method was developed to determine separately volatile and nonvolatile mercury in soil by a heating process in a furnace at 100 °C for 120 min. Although the nonvolatile mercury concentration was found to be stable through the year, the volatile mercury concentration was greatly decreased in summer. Thtries nd seems to be consistent with the fact that mercury concentration in the atmosphere is high in summer and low in winter in other reports.

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Rime as well as snow and ice monsters was sampled at Mt. Zaoh for three years from 1987to 1989, and insoluble metal concentrations were determined to get information on the transport of soil substances. As shown in Table 1, conspicuously high concentrations were found for the samples taken on March 5, 1987, and this observation was ascribed to the KOSA phenomenon (the wind-borne transport of loess particles), the occurrence of which was reported for March 5 and 6. There were high correlations between Al, which is an index element for the soil, and most of the other metal concentrations. Furthermore the data for the KOSA and the non-KOSA periods were correlated by the same regression lines, which are shown in Fig.1. This result suggests that, whenever the wintry winds predominate, the KOSA particles are transported to Japan irrespective of the apparent occurrence of the KOSA phenomenon.

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Steady-state concentrations of singlet oxygen ([¹O₂]_ss) in two Japanese lake waters were determined by using 2, 5-dimethylfuran as a trapping agent. Under solar-simulated irradiation (300 W xenon lamp + pyrex 7740 glass), surface values of [¹O₂]_ss were (2.1-6.3) × 10^-14 mol⋅dm^-3 in the Kitagata lake waters (eutrophic lake) and (2.1-4.0) × 10^-14 mol⋅dm^-3 in the Bushu lake waters (origotrophic lake). In both lakes, [¹O₂]_ss increased with increasing COD measured by permanganate method during spring and summer, and decreased with decreasing COD during fall and winter (Tables 1, 2). The correlation coefficients between [¹O₂]_ss and COD were O.87 for the Kitagata lake, 0.75 for the Bushu lake and 0.90 for the whole data (Fig.1). In the Kitagata lake waters, the fractions in the molecular weight range 500-10000 and lower than 500 exhibited large contributions (>40%). On the other hand, the fractions in the molecular weight range higher than 10000 exhibited a large contribution in the Bushu lake waters (>40%). The values of [¹O₂]_ss of all fractions of both lake waters in July. were larger than those in February but the percentage contribution of each fraction did not appreciably change in both months (Tables 3, 4). Quantum yields for formation of singlet oxygen (φ¹O₂)in both lake waters showed a decrease with increasing wavelength.φ¹O₂ ranged from 0.009 to O.018 in the Kitagata lake waters and from O.002 to 0.010 in the Bushu lake waters, respectively (Fig.3). Half-lives (t_1/2) of chlorophenols by singlet oxygen induced decomposition in the top meter of the Kitagata lake were estimated (Table 6).

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The purpose of this work is to reveal the kinetic nature of chemical oxygen demand (COD)determined by acidic permanganate method (JIS K0102-1986-17). Integrating rate equation (3)for the consumption of permanganate,
dx/dt=k(b-x)(c-x) (3)
where b and c are the initial concentration of permanganate and an organic compou nd, respectively, x is the concentration of permanganate consumed by the oxidation of the orga nic compound, k is rate constant, and t is reaction time, equation (4) is obtained.
k=1/(b-c)t In nc b(c-x)/c(b-x) (4)
For a given k value, one can calculate the titrant volume (a) of permanganate for various sample volumes (V), using equation (4). The full logarithmic linear relationship (2) holds between the calculated a and V with correlation coefficients above 0.9985.
log α= logh+nlogV (2)
The n values determined by least-squares method are O.74-1.00 (Table 1), which are in good agreement with the experimental values, n = 0.807-0.907.

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Removal characteristics of phosphonate and phosphinate ions in electroless nickel plati ng waste solution with Yatugatake volcanic ash soil (Y-2) have been investigated from the standpoint of chemical kinetics. Phosphon ate and phosphinate ions in solution have been found to be removed by an anionexchange reaction between the ions in solution and OH^- ions of Y-2, accompanied with a neutralization reaction between H⁺ ions in solution and OH^- ions of Y-2. Rate determing steps of the removal reactions have been estimated to be a film diffusion control and the film mass transfer coefficients for the phosphonate and posphinate ions were 1.7 x 10^-4 cm/s and 5.0 x 10^-5 cm/s, respectively.

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The sublimation pressures of six organic mercury(II) compounds (CH₃HgCl (MMC); CH₃HgBr (MMB); CH₃HgI (MMI); C₂H₅HgCl (EMC); C₂H₅HgBr (EMB); C₂H₅HgI (EMI))were determined for the first time using a newly designed vacuum apparatus. The temperature dependences of the sublimation pressures obtained by the least squares method were as follows (P = Pa unit and T = absolute temperature).
MMC : 1nP = 1.86 × 10⁶T^-2 -14.28 × 10³T^-1 + 31.36 (10-150°C)

MMB : 1nP = 3.38 × 10⁶T^-2 -24.73 × 10³T^-1 + 49.33 (10-120°C)

MMI : 1nP = 2.93 × 10⁶T^-2 -20.93 × 10³T^-1 + 41.26 (1O-15O°C )

EMC : 1nP = 6.39 × 10³T^-1 + 22.11 (100-150°C, r = 0.960)

EMB : 1nP = 9.24 × 10³T^-1 + 28.74 (100-160°C, r = 0.979)

EMI : 1nP = 7.76 × 10³T^-1 + 25.46 (100-160°C, r = 0.991)
The enthalpy changes for sublimation of methylmercury (II) halides at 20°C calculated using the above equations were smaller than those of ethylmercury (II) halides. In other words, the sublimation pressures of methylmercury (II) halides at 20°C were enormously larger than those of ethylmercury (II) halides. In addition, it was worthy of remark that the pressure of MMC (77.78 × 10³Pa), which had been known as the causal agent of so-called "Minamata Disea se", was several hundred times larger than that of metallic mercury (0.22 × 10³Pa at 20°C), whose vapor is known to be very poisonous even at room temperature. As one of the important thermo dynamical quantities, the molar volumes at respective melting point were also determined. As the result, the differences of the sizes of alkyl group and halogen were clearly reflected in these molar volumes.

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We studied on the repellent activity of stilbene glucosides and their derivatives against the blue mussel, Mytilus edulis. Based on the repellent activity of these compounds, the whole structure of the stilbene glucoside ester was shown to be important to exhibit the repellent activity.

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Some products of the degradation of hydrochlorofluorocarbons (HCFCs) by reaction with Cl atoms and O₂ were studied by FT-IR. The degradation of CH₃CCl₂F(HCFC 141 b) was initiated by H abstraction, and then CH₂CCl₂F was oxidized, leading to formation of either HCHO and COClF or CCl₂FCHO, and finally COClF, CO and CO₂ were formed. In the addition reaction of Cl to CH₂CCIF and subsequent reactions, both CH₂ClCOF and COClF were observed. It was presumed that CHCl₂CF₃(HCFC 123) reacted with Cl and the produced radical was oxidized to CF₃COCl. On the other hand, in the reaction of CHCl₂CCl₃ with Cl and O₂, CCl₃COCl, COCl₂, CO and CO₂ were produced and it indicates that C-C bond cleavage took place. CF₃CF₂CHCl₂ (HCFC 225 ca) and CClF₂CF₂CHCIF(HCFC 225 cb) were degraded to CF₃CF₂COCl and CClF₂CF₂COF, respectively.

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Evaporation rates of pure and binary systems of chlorinated C_1-2 hydrocarbons were measured at 298 K and compared with those estimated from the Knudsen type equation. As the binary solvent mixtures, 10 kinds of chlorinated C_1-2 hydrocarbons were combined with 4 kinds of alcohols of C_1-4, 5 kinds of alkanes of C_6-10, and 3 kinds of aromatics (benzene, toluene, and o-xylene). The evaporation rates of the mixtures observed agreed with those estimated from the known evaporation rates of the pure solvents and from the mean evaporation coefficients depending on the gas-phase turbulence using the activity coefficients calculated from the UNIFAC method.

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The stability of copper-humic acid complexes in acidified solutions was investigated by the pH and conductometric titration methods. Fluka humic acid and humic acids extracted from peat (Shinshinotsu, Sarobetsu, Bibai in Hokkaido) were used in this work. The evaluation of stability of the copper complexes were performed by comparing with the titration curves of model ligands (EDTA, citric acid, phenylalanine, hydroxyhydroquinone). It was found that the copper complexes with the humic acids of Fluka and Shinshinotsu were stable in acidified solutions, while the humic acids of Sarobetsu and Bibai were dissociable. The FTIR spectra of the humic acids and the pH titration curves of the model ligands suggested that, in the cases of the stable complexes, the carboxyl groups in the humic acids which have low pKa values would contribute to the complex formation. In the cases of the dissociable complexes, the phenolic hydroxyl groups would contribute to the formation.

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Polychlorinated dibenzo[b, e][1, 4]dioxins (PCDDs) and Polychlorinated dibenzofurans (PCDFs), called as "the dioxins" in general and Polychlorinated biphenyl (PCB) are well-known to be the most toxic substances and to be difficult to decompose in the natural environment because of their stable properties, and to be polluting the environment globally and accumulating in the animals and human body. This paper summarized and overviews the sources, the generation mechanism, some analytical problems, and the emission control of dioxins from municipal solid waste (MSW) incinerators based on the research results of the author's group and the investigation and available literature data, and describes the thermal destruction of waste liquid PCB. Incineration of wastes seems to be one of the major sources of "the dioxins" with serious public concerns. Main results of research as follows, 1) concenrations of dioxins in the flue gas and fly ash from the MSW incinerators are measured and it makes clear that the dioxins are mainly synthesized through the cooling zone of waste heat boiler and the formation of dioxins takes occur in the electrostatic precipitator when the inlet temperature of gas is above 200°C. It was concluded based on the many researches that the carbon and metals in the fly ash act as the catalyzer of formation of dioxins.2) The dioxins are also formed through the filter in the sampling procedures kept above 120°C. The author's group proposed the recommendable sampling and analytical procedures.3) The generation mechanism are investigated and proposed the emission control methods of dioxins from MSW incinerators. It was indicated that the waste liquid PCB can thermally be decomposed in the high temperature conditions with enough residence time. Based on the investigation, the waste liquid PCB of about 5500 tons was thermally destructed and its results are described.

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Catalytic decomposition and selective reduction of nitrogen monoxide over copper ion-exchanged zeolite catalysts have been proposed as a new method for removal of NO. The copper ion-exchanged ZSM-5 zeolite(Cu-ZSM-5) was the most active catalyst for NO decomposition. Repeated ion exchange of the ZSM-5 zeolite using aqueous copper(II) acetate solution or addition of ammonia into the aqueous copper(II) nitrate solution brought about the excess loading of copper ions above 100% of exchange level. The activity of the resulting zeolites increased with increasing exchange level and was significantly high even in the presence of oxygen and in the high GHSV region. It was clarified for Cu-ZSM-5 by using IR, ESR, phosphorescence, TPD, and CO adsorption measurements that (1) the Cu²⁺ ions exchanged into zeolite were reduced to Cu⁺ and/or Cu⁺-Cu⁺ through evacuation at elevated temperature, (2) after exposure to oxygen at 773 K about 40% copper ions in zeolite existed as Cu⁺ ions, and (3) the NO^- adsorbed on Cu⁺ was an intermediate in the NO decomposition and redox cycle of Cu⁺↔Cu²⁺ proceeded in the zeolite through the decomposition reaction. The selective reduction of NO by hydrocarbon in the presence of oxygen over CuZSM-5 was remarkably effective for NO removal at low temperature (473-573 K). The rate of Cu-ZSM-5 at 525 K was much higher than those of H-zeolite and alumina catalysts at 673 and 773 K, respectively. The activity for this selective reduction in NO+C₃H₆-1-O₂ system was not seriously poisoned by the addition of So₂.

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Pd, Ni, Pt supported on TiO₂ were effective for hydrodechlorination of CFC 113. The reaction took place at > 150°C and C₂H₂F₂, C₂F₃Cl and C₂H₂F₂ and C₂H₃F₃ were formed over the catalysts, respectively. C₂F₃Cl was formed over Co/TiO₂ at 350°C and the same reaction took place over MnTiO₃ at >500°C. Pd/C tends to substitute hydrogen atoms for chlorine atoms so that CF₂HCFH₂ was formed from CFC 113 with high selectivity of more than 85%. The activities of Rh/C and Pt/C were smaller than that of Pd/C. The addition of 2 mol% of water vapor did not affect the reaction but supressed the formation of CH₄ and promoted the formation of CO at>300°C. Plots of the catalytic activity against the heat of formation of metal chlorides gave a volcano shape. This suggests that the reaction proceeded via chlorination and dechlorination of the catalyst surface. MnTiO₃ was so stable that XRD pattern decreased slightly in intensity after the CFC 113-H2 reaction for 25 h at 550°C. The structure of Cr₂O₃ was not changed after the reaction at 350°C for 20 h by XRD.

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Dehydrochlorination of poly(vinyl chloride) (PVC) was investigated using metal chloride catalysts. The chlorides employed in this study were those of Al, Bi, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sn, V and Zn. AlCl₃ was most active for the dehydrochlorination of PVC followed by FeCl₃ and BiCl₃ in that order, but chlorides of V and Zn showed very low activities and the other chlorides were inactive. The catalytic activities of AlCl₃ and FeCl₃ were rapidly reduced with increasing reaction time and were completely missing at about 1 h, due probably to strong coordination of the catalysts to polyenes formed in PVC. On the other hand, the dehydrochlorination activity of BiCl₃ was not so high, but the catalyst showed no significan t deactivation with time and hence the final dehydrochlorination level was comparable to or slightly higher than that in the presence of AlCl₃. Silica-alumina, a typical solid acid, was inactive for the reaction of PVC although it was effective as a catalyst for vapor phase dehydrochlorination of 2-chloropropane. This result seems to be attributed to the difficulty in contacting solid PVC with active sites of the catalyst.

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In order to find if the spin states of deodorant constituents change during the absorption process of odor substances, an ESR study of the hydroxy carboxylic acid-Mn²⁺ systems has been undertaken. As samples, Mn²⁺/citric acid/silica gel, MnSO₄/citric acid, MnSO₄/_L-ascorbic acid, and MnSO₄/citric acid/L-ascorbic acid have been used. ESR spectra, when these specimens are evacuated, NH₃ gas introduced, evacuated again, air introduced, and then evacuated, have been recorded. The results have indicated that the concentration and the spin state of S=5/2 Mn²⁺ ion greatly changes during gas adsorption process. This change is affected an d is controlled by the presence of hydroxy carboxylic acid. The ESR spectra of MnSO₄/carboxylic acid complexes are broadened by exchange interactions, but their intensity analyses have shown that the intensity-gas adsorption profiles can be used to diagnose the deodorant capabilities.

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The direct decomposition of nitrogen monoxide (NO) was carried out over Cu-containing La_2-xA_xCu_1-yB_yO₄ mixed oxide catalysts with K₂NiF₄-type structure under the following conditions: NO ; 3.17% (He balance) and reaction temperature; 500-800°C. The effect of valency control of copper for Sr²⁺-substituted catalysts has been mainly investigated. Sr²⁺-or Ba²⁺-substitution for Le³⁺ increased the activity and it reached a maximum at x=O.5 for La_2-xSr_xCuO₄. The activity of La₁.₅Sr₀.₅CuO₄ normalized to the surface area was ten and three times higher than those of La₂Cua₄ and active La₀.₈Sr₀.₂CoO₃, respectively. The activity of La₁.₅Sr₀.₅CuO₄ was constant at least for 24 h. In contrast, the enhancement of the catalytic activity for the oxidation of propane by the Sr²⁺ substitution was not observed. It is noted that good correlation was observed between the average oxidation nu mber of copper and the activity for the direct decomposition of NO : The activity increased with the increase of the average oxidation number of copper and, especially the catalysts, of which the oxidation number of copper was above two, showed high catalytic activity for the direct decomposition of NO.

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From a view point of the control of environmental pollution, condensation of aqueous Hg (II) was studied. This con densation, that is an active transport, was performed by assembling a system from a source aqueous phase, a receiving aqueous phase including halide salt, and a filter-impregnated liquid membrane which separated the two aqueous phases. Liquid polybutadiene (LPB), epoxidized LPB (LE), and methylthio-substituted LPB derivatives (LSMe) were found to have the ability of selective active transport of Hg(II) when used as the liquid membrane in a mixture with o-nitrophenyl octyl ether. Unsaturated linkage in LPB, epoxy rin g in LE, and sulfide linkage in LSMe are all estimated as an active ingredient in liquid membrane to have interaction with Hg(II) and to induce the absorption of Hg(II) into the membrane from the source phase. The released Hg(II)from the membrane lies in an equilibrium with HgX₄^2- (X=halogen) in the receiving phase, which is inert to interact with the ingredient of membrane. Disappearance of this interaction suppresses reabsorption to the membrane and contributes to the active transport of Hg(II). Methylthio-substituted derivatives, among LPB derivatives tested, especially LSMe-b with higher concentration of sulfide linkage showed the best ability of selective active transport of Hg(II).

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The adsorption of Zn²⁺, pb²⁺, Ni²⁺, Hg²⁺, ca²⁺, mg²⁺, cr⁶⁺, NH₄⁺ and H⁺on Itaya zeolite consisting mainly of clinoptilolite and mordenite was investigated. The adsorption isotherms were found to be approximately expressed by the Freundlich equation.
x/m=kC^1/n
Where x is weight of ion, in grams adsorbed by m grams of zeolite, C is concentration of cation in solution g/l, and n and k are constants. In this experiment n is 3.82-0.89. Because Itaya zeolite has excellent adsorption capacity comparable to synthetic zeolit e (MS 5 A) or active carbon, it seems that a fixed bed of Itaya zeolite is applicable to removal of cations from waste water.

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Hydrated titanium oxide was prepared as a new adsorbent for the removal of orthophosphate in wastewaters. It was precipitated from titanium(IV) sulfate solution with sodium hydroxide and treated with sulfuric acid. From batchwise adsorption experiments the amount of phosphate adsorbed was larger at pH 2 than at pH 7. A linear relationship on a log-log graph paper was obtained by plotting the equilibrium concentrations of phosphate in the solutions and in the adsorbent, indicating that the adsorption obeys the Freundlich's isotherm. The index and the coefficient of the equation were large enough for the material to adsorb efficiently phosphate from solutions. When phosphate was adsorbed on hydrated titanium oxide, an equivalent amount of sulfate+hydroxide ions were liberated from the adsorbent, mainly sulfate at pH 2 and hydroxide at pH 5, suggesting that these ions on the surface of the adsorbent were exchanged with dihydrogenphosphate ions in the solutions. From columnwise experiments, it was observed that, at the end of adsorption, the amount of phosphate adsorbed was about 20 times larger at pH 2 than at pH 7. When 0.05 mmol⋅dm^-3 phosphate solution of pH 7, containing O.6 mmol⋅dm^-3 calcium ions and a sufficient amount of hydrogencarbonate (1 mmol⋅dm^-3), was passed through a column packed with 3 g hydrated titanium oxide, about 90% of phosphate was adsorbed from a very large volume of influent. This suggests the possibility of the semipermanent removal of phosphate by a limited amount of the adsorbent. In the case where concentration of phosphate was 1 mmol⋅dm^-3, about 80% of this ions could be semipermanently removed. For the removal of phosphate for a long time, intermittent backwashing should be made to maintain the uniform flow of wastewater.

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A good indicator of biological activity is required for the activated sludge process to operate efficiently in biological treatment plants. The relationship between dehydrogenase activity (DHA) using INT (2-(p-iodopheny1)-3-(p-nitropheny1)-5-phenyltetrazolium chloride) and oxygen-uptake rate (OUR) on the laboratory-scale experiment was investigated for 3 months. Both DHA and OUR increased in the presence of substrate, but a substrate in excess had no adverse effect on them. Although the condition of activated sludge varied from the bulking stage to the flocculation stage during the experimental period, a good linear relationship (DHA=0.145⋅0UR+22.0, r=0.849, n=62) between DHA and OUR was observed.

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A new practical disinfection method for drinking water has been developed by using an electrodialysis system with cation- and anion-exchange membranes. Short distance between the membranes, large effective area of the membranes and slow flow rate of E. coli suspended solutions through the desalting chamber have been found to be effective for the practical purpose. Perfect devitalization of the Tama river has been possible by using a practical handy electrodialysis system (0.24 or O.48 A⋅dm^-2) with the distance of 0.02dm between the ion-exchange membranes, the effective membrane area of 2.09 dm² and flow rates of O.3-0.5 dm³⋅min^-1.

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