Geochemical Journal, Vol. 14, pp. 203 to 226, 1980 203 Concentrations of 21 metals in the suspended solids collected from the principal 166 rivers and 3 lakes in Japan HISAYUKI TERAOKA and JUN KOBAYASHI Institute for Agricultural and Biological Sciences, Okayama University, Kurashiki 710, Japan (Received July 21, 1980; Accepted October 20, 1980) In the analysis of natural water, it would be interesting to determine small but significant quantities of trace metals which are concentrated in suspended solids, since some of these metals, derived from geologic formations, mines and industries not only influence the environment for men and animals, but will also help us in tracing metallic resources. Taking advantage of the nation-wide chemical investigations conducted by JUN KOBAYASHI,FUJI MORII and coworkers on various constituents dissolved in the principal Japanese rivers and lakes, the present authors could analyze major and minor metallic elements in the suspended solids by the emission spectrographic method. The following are the results obtained: (1) Markedly higher concentrations of minor elements such as Pb, Zn, Cu, Ni, Mn and Co were found in the suspended solids than in unpolluted soils or in the continental crust reported by TAYLOR (1964). (2) The concentrationsof Mn,Cu, Ni, Pb and Sri were found to be markedlyhigh in the Northeastern provinces. This must be due to the higher concentrationsof these metals distributedin geologicformations in this section as well as to the influence of many copper and other mines. (3) The distribution of Be happened to divide Japan into two halves. It is markedly lower in the eastern half. Positive correlations were also observed between the concentrations of Be and those of Al and Ti. (4) Owingto the extremely acid nature (pH 2.0) of the Yu River(No. 42) in the Tone river system, caused by the Kusatsu hot sulfuric springs,the concentrationsof all metals except Si showed the lowest values,while Si had the highest value. Other inorganic acid rivers which are distributed mostly in the Northeastern provinces, i.e. the Agatsuma River (No. 43, pH 4.3) of the same system and the Ara River (No. 13, pH 3.6), and acid lakes, i.e. Lake Tazawa(No. 32, pH 4.4) and Lake Inawashiro(No. 57, pH 4.5) showed about the same tendency. INTRODUCTION water samples collected once a month, 12 times a year, from more than 500 selected sites along Information on the amount of chemical con the principal rivers and lakes throughout the stituents dissolved in river water is important whole territory of Japan (KOBAYASHI,1951; not only for studying the process of weathering KOBAYASHI,1960), and moreover from other and erosion of the surface of the earth, but also Asian countries (KOBAYASHI,1959). for a wide range of human activities including In this study covering various geological agriculture, industry, fishery and hygiene. As features, KOBAYASHInoticed striking correlations early as 1941 when the water had as yet hardly between (1) the distribution of Si02 content been polluted, KOBAYASHI,one of the authors, dissolved in river or irrigation water and the SiO, started a nation-wide chemical investigation, content in rice straw by districts on the one hand continuing for several decades, on the dissolved (KOBAYASHI,1967; KOBAYASHI,1971), and (2) constituents, such as Ca, Mg, Na, K, HCO3, the chemical composition of river water and SO,, Cl, SiO2, PO,, NO,, NHL and COD in the death-rate from apoplexy (stroke) which has 204 H. TERAOKAand J. KOBAYASHI been the leading cause of death in Japan, on river water for such purposes as irrigation of rice the other (KOBAYASHI,1957). After this second fields, industry and tap water, but also for finding, many articles have been published show avoiding man-made pollution caused by waste ing an inverse relationship between the hardness water from industries and cities downstream. of local water supplies and mortality rates from In the actual sampling at the selected places, cardiovascular diseases in various countries care was taken to collect the water from the (SCHROEDER,1960; MASHIRONIet al., 1979). midstream of the river, where the water moves Further, by means of emission spectro deeply and rapidly. As a rule, the water samples graphic analysis, KOBAYASHIfound in 1960 the were simultaneously collected once a month, first clue to the cause of the "Itai-Itai" disease 12 times a year, from the selected 169 sites a very strange and miserable osseous disease along the principal rivers and lakes. The sampl inducted by chronic poisoning with cadimium ing period continued for three years from which was released into a river from the biggest October 1972 through September 1975, as zinc mine of Japan around the time of the Japan was divided into three parts for analytical Second World War (KOBAYASHI,1971; KoBA purposes. YASHI, 1979). After this finding the present It was fortunate that, in selecting the places authors made further applications of this method and collecting the samples, special cooperation which permits simultaneous determination of could be obtained from 36 prefectural govern many kinds of metal even with a very small ments in response to KOBAYASHI'srequest to quantity of sample ash (TERAOKAand KOBAYA support this nation-wide investigations of waters. SHI, 1977; TERAOKAet al., 1978). From October 1972 to September 1975, Analytical procedure The suspended solids when a second series of nation-wide chemical were filtered out with a small piece (3.6cm investigations of river and lake waters was diameter) of Toyo filter paper No. 6 fixed in a carried out by JUN KOBAYASHI,Fuji MoRHand filtering funnel, dried in a drying oven at 105°C, coworkers to make clear the chemical influences and measured for the dry weight of the solids. due to the marked pollution in the 1970's The 12 solids obtained from each site during a (KOBAYASHIet al., 1976; KOBAYASHIet al., 1978), year together with the filter paper were mixed the authors took advantage of this survey to and ashed at 450°C. After measuring the determine the concentrations of 21 metals (Si, weight, the ash was analyzed by emission spec Al, Fe, Ca, Mg, Na, Ti, Mn, Ba, Zn, Sr, Zr, trographic method. This analytical method is V, Cr, Cu, Ni, Co, Pb, Sn, Ag and Be) in ashes of one of the most appropriate methods for analyz suspended solids obtained from water samples, ing various metals in suspended solids, because it which were collected from 169 sites along the makes possible the simultaneous determination principal rivers and lakes of Japan. The results of more than 20 elements with only a small thus obtained are reported in this paper. quantity of sample ash. Sample ash mixed with carbon powder con taining the internal standards (Pd and Gel was EXPERIMENTAL burnt until the mixture volatized in a do-arc Collection of samples The sampling places generated in an argon-oxygen atmosphere which shown in Fig. 1 and Table 1 were selected with is effective in eliminating the CN-bands and preference for those parts of the rivers where decreasing the background. The gap between they are about to enter the downstream plains the electrodes was kept at 4mm during the after running through the mountainous upper burning time, and only the middle part (1 mm) and middle stream areas. In Japan, where the of the arc was passed through on the spectro topography is steep and rivers run swiftly, these graph slit by midway focusing method. A 7 places are important not only in utilizing the step rotating sector was used. Working curves Concentrations of 21 metals in the suspended solids 205 X "a9 rCA~r '_ P, lY -\ n C\ FId r J J i 1 0 ~,r a. :-,~ O n Fig. 1. Sampling places of the principal 166 rivers and 3 lakes in Japan 206 H. TERAOKA and J. KOBAYASHI Table 1. Places of sampling and analytical results of suspended solids (S. S.) collected from the principal 166 rivers and 3 lakes in Japan, for three years from October 1972 through September 1975. Concentrations of S. S., I. L. and 21 metals are the average of 12 different samples collected once a month, 12 times a years. I.L. Si No. Name of river Place of sampling S.S. (Ppm) (%) 1 Teshio Hokkaido Nayoro-shi Nayoro-o hashi 36 25 25 2 Ishikari Hokkaido Kawakami-gun Aibetsu-cho Nakaaibetsu 104 17 26 3 Ishikari Hokkaido Fukagawa-shi Midori-machi 41 27 26 4 Sorachi Hokkaido Akabira-shi 101 25 29 5 Ishikari Hokkaido Ebetsu-shi Upstream the Chitose R. joins 81 21 28 6 Chitose Hokkaido Ebetsuchi Hashi of National road 12 110 16 29 7 Toyohira Hokkaido Sapporo-shi Toyohira-ku 81 27 26 8 Tokachi Hokkaido Kasai-gun Memurocho 61 37 26 9 Tokachi Hokkaido Nakagawa-gun Toyokoro-cho Moiwaohaslu 58 35 28 10 Tokoro Hokkaido Tokoro-gun Tanno-cho 2-ku 79 29 26 11 Iwaki Aomori-ken Nakatsugaru-gun Iwaki-machi Nyoraise 22 22 25 12 Hira Aomori-ken Minamitsugaru-gun Owani-cho Shukugawara 25 31 25 13 Are Aomori-shi Takada 52 37 28 14 Oirase Aomori-ken Towada-shi Osaka 11 35 29 15 Mabuchi Aomori-ken Hachinohe-shi Kushibiki Kushibiki-hashi 23 31 26 16 Kuji Iwate-ken Kuji-shi Okawamecho Mitsuka-machi 3.2 41 25 17 Heii Iwate-ken Shimoheu-gun Niisato-mura Moichi 4.1 31 26 18 Kitakami Iwate-ken Morioka-shi Tatemukaicho 17 52 19 19 Shizukuishi Iwate-ken Morioka-shi Ota 14 30 26 20 Sarugaishi Iwate-ken Waga-gun Towa-cho 5.4 42 25 21 Kitakami Iwate-ken Kitakami-shi Tachibana 16 33 26 22 Isawa Iwate-ken Isawa-gun Isawa-cho 9.6 21 25 23 Kitakami Miyagi-ken Tome-gun Nakadacho 21 31 27 24 Hazama Miyagi-ken Kuriharagun Wakayanagicho Kawaminami 18 23 28 25 Eai (Arao) Miyagi-ken Tamazukuri-gun Iwadeyama-machi 9.1 30 28 26 Abukuma Fukushima-ken