- Email: [email protected]
Short-term cycle of eolian dust (Kosa) recorded in Lake Kawaguchi sediments, central Japan
ARTICLE IN PRESS
Atmospheric Environment 39 (2005) 3335–3342 www.elsevier.com/locate/atmosenv
Short-term cycle of eolian dust (Kosa) recorded in Lake Kawaguchi sediments, central Japan Tomohiro Kyotania,b,d,, Satoshi Koshimizub, Hiroshi Kobayashic a Japan Science and Technology Corporation, 4-1-8, Honmachi, Kawaguchi, Saitama 332-0012, Japan Earth Science Division, Yamanashi Institute of Environmental Sciences, 5597-1, Kenmarubi, Kamiyoshida, Fujiyoshida, Yamanashi 403-0005, Japan c Yamanashi Institute for Public Health, 1-7-31, Fujimi, Kofu, Yamanashi 400-0027, Japan d Bussan Nanotech Research Institute Inc., Mitsui & Co., Ltd. Nanotech Park, 2-1, Koyadai, Tsukuba, Ibaraki 305-0074, Japan b
Received 29 June 2004; received in revised form 4 January 2005; accepted 4 January 2005
Abstract The fluctuation during the last 100 yr of the eolian dust (Kosa aerosol) originating from arid and semi-arid areas of China has been reconstructed by using the sediments from Lake Kawaguchi, central Japan with high temporal resolution. The quantification of Kosa contribution to the sediments was carried out by a new method using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX) proposed by us. The correlation plot of (Na2O+K2O) contents against SiO2 was used for individual Si-rich particles having SiO2 content over 80%. The Kosa fraction of Si-rich particles in Lake Kawaguchi sediments during the last 100 yr is approximately 10–30%. The fluctuation of the Kosa fraction during the last 100 yr does not coincide with that of the total amount of Si-rich particles, because detrital components from Japanese igneous rocks control the fluctuation of the total number of Sirich particles. The discrimination method based on single particle analysis is more effective than that of bulk analysis for the lake sediments formed by complex matrix components. We can first show a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation. Higher sedimentation rates (5–10 yr-cm) of the Lake Kawaguchi sediments and the new analytical method using SEM-EDX revealed a remarkable fluctuation pattern of Kosa aerosol, suggesting climate cycles much shorter than glacial–interglacial. Such short-term cycles may be related to sun-spots. The number of days of Kosa events during the last 30 yr, obtained by visual observation by Meteorological Agency of Japan, also supports the presence of such a short-term cycle. r 2005 Elsevier Ltd. All rights reserved. Keywords: Kosa aerosol; Si-rich particles; Short-term cycle; Climate change; Lake Kawaguchi sediment; SEM-EDX
1. Introduction The eolian dust, called the Kosa (yellow sand) aerosol (Kadowaki, 1979; Iwasaka et al., 1979; Nishikawa et al., Corresponding author. Bussan Nanotech Research Institute
Inc., Mitsui & Co., Ltd. Nanotech Park, 2-1, Koyadai, Tsukuba, Ibaraki 305-0074, Japan. Fax: +81 29 839 9430. E-mail address: [email protected] (T. Kyotani).
1991) in Japan, originating from arid and semi-arid areas of China and reaching as far as the north Pacific Ocean (Duce et al., 1980; Uematsu et al., 1983, 2000; Okada et al., 1990; Leinen et al., 1994), is an effective indicator of the aridity in the source area and of paleoclimate in eastern Asia. The past variation has been reconstructed using mainly marine sediment core samples as a course of research for the problem of global warming (Mizota and Matsuhisa, 1985; Hovan
1352-2310/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2005.01.026
ARTICLE IN PRESS 3336
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
et al., 1991; Okamoto et al., 1996; Irino and Tada, 2000; Kawahata et al., 2000). The Kosa flux varies significantly corresponding to glacial–interglacial cycles, with higher contribution during glacial periods and lower contribution during interglacial periods (Hovan et al., 1991; Irino and Tada, 2000; Kawahata et al., 2000). The presence of millennium-scale fluctuation of Kosa flux with a magnitude as large as that of Milankovitch-scale variation is also well known from the age profiles for marine sediments (Irino and Tada, 2000; Kawahata et al., 2000). The number of samples used to cover long time ranges such as the last 150–200 ky is normally 100–200 samples with intervals of approximately 1 ky (Irino and Tada, 2000; Kawahata et al., 2000). Therefore, since the time resolution in conventional age profiles of Kosa flux is usually low, periodic fluctuation patterns much shorter than glacial–interglacial cycles have not yet been detected. The use of lake sediments formed by the higher sedimentation rates is better for short time resolution analysis than that if marine sediments. Since the contribution of terrestrial materials other than eolian dust like Kosa is usually low for pelagic marine sediments such as the Pacific Ocean (Syers et al., 1972; Windom, 1975; Duce et al., 1980; Leinen and Heath, 1981; Blank et al., 1985; Nakai et al., 1993; Leinen et al., 1994; Merrill et al., 1994), the quantification of Kosa contribution to such marine sediments has been carried out successfully on the basis of bulk chemical and mineralogical analysis, for example of quartz (Irino and Tada, 2000; Kawahata et al., 2000), aluminum (Duce et al., 1980; Uematsu et al., 1983; Kawahata et al., 2000), etc. On the other hand, lake sediments located in an inland area should be strongly affected by the surrounding environment. Therefore, it is difficult to discriminate the Kosa particles of small or trace amounts in lake sediments using bulk analysis that gives information only for average compositions. Thus, the methods for the identification and quantification of Kosa particles in lake sediments formed by complex matrix components have not yet been established. In this study, we proposed a new method for the identification of individual Kosa particles using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX). Here, we have identified and quantified grain by grain Si-rich particles derived from Kosa aerosol in sediments from Lake Kawaguchi, Central Japan, and found the fluctuation during the last 100 yr with short time resolution. Consequently, a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation was first discussed.
2. Study area and sediment core samples Lake Kawaguchi is located at the northern foot of Mt. Fuji, Yamanashi Prefecture, central Japan (351
310 N, 1381 460 E). The detail of the sampling location is shown in Fig. 1. The stratigraphy and geological age of 90 m borehole core from Lake Kawaguchi were already reported (Koshimizu et al., 1999); the sedimentation rates of the silt beds are approximately 5–10 yr-cm. Samples used in this study are a silt bed up to 20 cm in depth from the top of the sediment core at Lake Kawaguchi and were cut every 1 cm. As shown in Fig. 2, age-control in the samples was also confirmed by the depth profile of polycyclic aromatic hydrocarbons (PAHs) concentrations (Kobayashi et al., 2000). It has been well known that the emission into the environment of PAHs increased suddenly in the last 100 yr and the maximum point in the depth profile of PAHs concentrations corresponds to 1970–1960 (Muller et al., 1977; Prahl and Carpenter, 1979; Handa and Ohta, 1983; Cranwell and Koul, 1989). The depth profile of total concentration of PAHs up to 20 cm in Lake Kawaguchi sediments showed the maximum values at 8–9 and 9–10 cm depths (Kobayashi et al., 2000). Therefore, judging from both the geological age of the 90 m borehole core (Koshimizu et al., 1999) and the PAHs profile (Kobayashi et al., 2000) in the surface layer, the sedimentation rates up to 20 cm depth could be estimated to be approximately 5–10 yr-cm, although the rates in the last 30–40 yr seem to be high (3–5 yr-cm). Consequently, 20 cm overall covers the last 100 yr.
3. Methods 3.1. Si-rich particles as an effective indicator of Kosa aerosol We have already described a new method of SEMEDX for the identification of individual Kosa particles in atmospheric aerosol with the size below 10 mm (Kyotani and Koshimizu, 2001). Si-rich particles (mainly quartz) having SiO2 content over 80% can be used as an effective indicator in this region. The correlation plot between (Na2O+K2O) and SiO2 contents in individual Si-rich particles from atmospheric aerosol, determined grain by grain, by SEM-EDX using a standardless f(rz) correction program, shows a sharp and clear seasonal variation (Fig. 3). Furthermore, the distribution in spring time concentrates in a specific area, and is closer to those in the China loess and desert sand compared to non-Kosa aerosol (Figs. 3 and 4). Although the source region in China of Kosa aerosol is so wide, the distribution area of real Kosa aerosol observed in Japan is quite narrow and is fixed. The observation fact is the greatest reason for the determination of the Kosa area. Therefore, two source materials (loess CJ-1 and desert sand CJ-2) of Kosa were used not to determine the Kosa area but to compare with the
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3337
Fig. 1. Five lakes at the northern foot of Mt. Fuji, central Japan and the sampling site.
distribution area of real Kosa aerosol observed in Japan (Figs. 3 and 4). Thus, individual Si-rich particles derived from Kosa aerosol can be clearly discriminated from the Japanese igneous rocks by differences of the distribution areas of (Na2O+K2O)/SiO2. 3.2. Quantification of Kosa contribution to lake sediments The identification method described above was applied to the Lake Kawaguchi sediments, and the quantification of Kosa contribution was carried out by counting the number of individual Kosa particles in each sample. The core samples contained a large quantity of organic materials. Prior to SEM-EDX analysis, each sample was converted to the specimen suitable for single particle analysis. At first, the sediment core samples were dried at 110 1C for 2 h. 0.5 g of the dried and powdered sample was ignited at 1000 1C for 6 h, and 0.5–1.0 mg of the ignited sample was washed in a 10 ml volume of 6 N hydrochloric acid for 20 min by ultrasonication. The residual particles were filtered off through a 0.45 mm membrane filter, and washing with 3 ml of water was repeated 5 times to remove any hydrochloric acid from the particles on the filter. After drying for 30 min at 110 1C, the particles on
the filters were detached by double-sided adhesive carbon tape and were fixed on the aluminum sample stands (15 mm in diameter, 5 mm in height) for SEM-EDX. Thereafter, the particles were carbon coated (200 A˚) and the specimens were subjected to the SEM-EDX analysis. The details of the experimental conditions for SEM-EDX analysis have been described elsewhere (Kyotani and Koshimizu, 2001). It was confirmed that the evaporation of alkaline elements from Si-rich particles and the contamination from coexisting organic matters can be neglected during the ignition procedure. Namely, these procedures do not affect the distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles. This shows that Si-rich particles are composed of extremely stable components, that is, quartz. About 200 mineral grains with the size below 10 mm in the residues were analyzed by SEM-EDX for each sample, and the distribution areas of (Na2O+K2O)/SiO2 for individual Si-rich particles were evaluated likewise in the case of atmospheric aerosol as shown in Figs. 3 and 4 (Kyotani and Koshimizu, 2001). Fig. 5 shows an example of the distribution of (Na2O+K2O)/SiO2 for individual Si-rich particles from the Lake Kawaguchi sediment. The distribution area of individual Si-rich particles derived
ARTICLE IN PRESS 3338
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Fig. 2. Fluctuation of polycyclic aromatic hydrocarbons (PAHs) concentrations in Lake Kawaguchi sediments, central Japan. This figure was illustrated using the data of Kobayashi et al., 2000.
from Kosa confirmed for real atmospheric aerosol (Kyotani and Koshimizu, 2001) is drawn using an oblique line. Si-rich particles found in this specific area (Kosa area) were regarded as the Kosa particles. Other Si-rich particles are mainly from Japanese igneous rocks. The particles from Japanese igneous rocks, fallen into the area where both sodium and potassium were not detected, are mainly background particles in the northern foot of Mt. Fuji (Kyotani and Koshimizu, 2001). The background particles may be mainly derived from Misaka mountains composed of pyroclastic and volcanic rocks located at the northern region of Lake Kawaguchi. The Kosa fraction was calculated as the relative ratio of the number of Si-rich particles found in the Kosa area to the total number of Sirich particles in the samples. The content of Si-rich particles was calculated as the relative ratio of the total number of Si-rich particles to the total number of mineral particles measured in the samples. Fig. 3. Seasonal variation of the distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles from atmospheric aerosol collected at Kofu Basin that is mainly granitic and sedimentary. Each point expresses an individual particle. Lines indicate the distribution areas of granodiorite (JG-1a), andesite (JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). This figure was illustrated using the data of Kyotani and Koshimizu, 2001.
4. Results and discussion 4.1. Kosa fraction of Si-rich particles quantified by the present method The discrimination of Kosa particles based on the shape and grain size of minerals has often been done; it
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3339
Fig. 4. Distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles from atmospheric aerosol collected at the northern foot of Mt. Fuji that is mainly basaltic. Each point expresses an individual particle. Lines indicate the distribution areas of granodiorite (JG-1a), andesite (JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). This figure was illustrated using the data of Kyotani and Koshimizu, 2001.
has been reported that continental soil is relatively round quartz (Xiao et al., 1995; Okamoto et al., 1996; Kawahata et al., 2000) and the grain size of Kosa aerosol reaching Japan is mostly several microns (Kadowaki, 1979; Okada et al, 1990; Nishikawa et al., 1991). However, the application of this discrimination to lake sediments is difficult, because detrital particles from Japanese igneous rocks have shape and grain size characteristics similar to Kosa. Although eolian dust particles under Kosa phenomena include many minerals other than Si-rich particles (Ishizaka and Ono, 1982; Okada et al., 1990; Uematsu et al., 2000; Ro et al., 2001), the indicator available for paleo-environment analysis should be limited to minerals having high chemical stability. Si-rich particles mainly composed of quartz (Kyotani and Koshimizu, 2001) seem to be the best indicator for paleo-environment analysis. On the other hand, easily weathering minerals such as alkali feldspars, plagioclase, clay minerals, etc. are not suitable to the aim. Furthermore, the basaltic geology around Mt. Fuji originating from eruptive materials containing low percentages of quartz provides a lower background for the Si-rich particle discrimination in the present study than do other granitic or sedimentary regions (Kyotani and Koshimizu, 2001). Judging from these points, the chemical composition of individual Si-rich
particles was used as an indicator for paleo-climate analysis in Lake Kawaguchi sediments. Fig. 6 shows the fluctuations of the total number of Si-rich particles (a) and the Kosa fraction (b) during the last 100 yr. The Kosa fraction of Si-rich particles is approximately 10–30% except for 16–17 cm depth. Therefore, detrital components from Japanese igneous rocks affect essentially the total number of Si-rich particles in the Lake Kawaguchi sediments. This result indicates that the method based on single particle analysis is more effective for the lake sediments formed by the complex matrix components than bulk analysis. Bulk analysis using average compositions will not provide such a fractional contribution. 4.2. Short-term variation of Kosa aerosol The depth profile of the total number of Si-rich particles (Fig. 6a) differed from that of the Kosa fraction (Fig. 6b) during the last 100 yr, although both of them coincide between 15 and 20 cm. The total number of Sirich particles (Fig. 6a) has gradually increased during the last 100 yr, except for 16–17 cm where the large input of Kosa aerosol to the lake is recognized. The large input at 1–2 cm depth is mainly attributed to Japanese Si-rich particles. On the other hand, the Kosa fraction
ARTICLE IN PRESS 3340
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Fig. 5. Example of the distribution of (Na2O+K2O)/SiO2 in individual Si-rich particles from the sediment core (depth:1–2 cm) at Lake Kawaguchi, central Japan. Each point expresses an individual particle. Lines indicate the examples of distribution areas (Kyotani and Koshimizu, 2001) in individual Si-rich particles from Japanese igneous rocks (granodiorite JG-1a, andesite JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). Kosa fraction (%) ¼ NKosa/ NSi 100; content of Si-rich particles (%) ¼ NSi/Nmi 100 (NKosa: the number of Si-rich particles found in the Kosa area; NSi: total number of Si-rich particles; Nmi: total number of mineral particles measured in the samples).
(Fig. 6b) has gradually decreased during the last 100 yr in spite of the recent desertification in China. It can be judged from the distribution areas of (Na2O+K2O)/ SiO2 in Fig. 5 that the present Kosa aerosol is mainly not from loess but from desert sand which is characterized by its relatively low content of SiO2. The Kosa fraction shows a clear fluctuation cycle corresponding to approximately 10–20 yr scale, since 1 cm sample contains 5–10 yr accumulation. Even if the Kosa fraction is a part of total flux, the result as shown in Fig. 6b is the first datum that shows the possibility of a short periodic cycle. The cycle becomes slightly shorter from the 10 cm depth (1970–1960) downward to the present. A 10-yr scale cycle has been observed in many other phenomena and the presence of climate change cycles at these extremely short time scales has been suggested (Kawakami, 1995 and references therein). These short time scale cycles were not observed in the marine sediments in the northwest Pacific Ocean (Kawahata et al., 2000; Okamoto et al., 1996) or the Japan Sea (Irino and Tada, 2000) which had extremely slow sedimentation rates. The higher sedimentation rates (Koshimizu et al., 1999; Kobayashi et al., 2000) of Lake Kawaguchi sediments and the new method first
Fig. 6. Fluctuations of the content of Si-rich particles (a) and the Kosa fraction (b) in Lake Kawaguchi sediments, central Japan during the last 100 yr. PAHs concentrations and the depth profile, see Fig. 2.
detected the remarkable fluctuation pattern of Kosa aerosol. As reference data, Fig. 7 shows the fluctuation in the number of days of Kosa events by year obtained by visual observation at 2 observatories (Lake Kawaguchi and Kofu City) in Yamanashi Prefecture from 1970 to 2001 (Kawaguchiko and Kofu Weather Stations, Meteorological Agency of Japan, 1970–2001). Although the visual monitoring data of Kosa aerosol observed at weather stations, Meteorological Agency of Japan has been partly compiled, the discussion has been done concentrating not on the fluctuation cycle but on the increase of Kosa events in the past 1–2 yr (Nishikawa et al., 2001). Fig. 7 shows clearly that the peak has appeared at an interval of about 10–13 yr and the number of days observed has gradually decreased during the last 30 yr. In this study, a certain relationship between the number of days of Kosa events and total Kosa flux is not clarified. Also, since the time resolution of our data in Fig. 6b is 5–10 yr accumulation and the observation period in Fig. 7 is only 30 yr, direct comparison among them may be difficult. But, the observation fact in Fig. 7 is important data which support the possibility of short-term variation such as 10-yr scale found by us. The 11 yr cycle is also observed on solar variability (Kawakami, 1995 and references therein). The
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3341
higher sedimentation rates and the new SEM-EDX method.
References
Fig. 7. Fluctuation in the number of days of Kosa events by year obtained by visual observation at 2 observatories (Lake Kawaguchi and Kofu City) in Yamanashi Prefecture from 1970 to 2001. This figure was compiled from the Monthly Summaries (1970–2001) of Kawaguchiko and Kofu weather stations, Meteorological Agency of Japan.
short-term fluctuation cycle of the Kosa fraction found in the lake sediments may relate to these climatic phenomena.
5. Conclusions Our measurement of individual Si-rich particles from Lake Kawaguchi sediments, central Japan lead to the following conclusions: (1) Grain by grain analysis was effective to determine the Kosa contribution in lake sediments. In this study, individual Si-rich particles derived from Kosa aerosol in the lake sediments could be identified and quantified successfully by using the distribution area of (Na2O+K2O)/SiO2 determined by SEM-EDX. (2) The Kosa fraction of Si-rich particles in the Lake Kawaguchi sediments during the last 100 yr is approximately 10–30% and does not coincide with fluctuation of the total amount of Si-rich particles. Detrital components from Japanese igneous rocks, being the major matrix, control essentially the fluctuation of the total number of Si-rich particles in the sediments. (3) The Kosa fraction of Si-rich particles shows a shortterm fluctuation cycle which corresponds to approximately 10–20 yr scale. Although the Kosa fraction is a part of total flux, the possibility of presence of the periodic fluctuation cycle much shorter than glacial–interglacial was first shown for Kosa aerosol by using both the Lake Kawaguchi sediments with
Blank, M., Leinen, M., Prospero, J.M., 1985. Major Asian aeolian inputs indicated by the mineralogy of aerosoles and sediments in the western North Pacific. Nature 314, 84–86. Cranwell, P.A., Koul, V.K., 1989. Sedimentary record of polycyclic aromatic and aliphatic hydrocarbons in the Windermere Catchment. Water Research 23, 275–283. Duce, R.A., Unni, C.K., Ray, B.J., Prospero, J.M., Merrill, J.T., 1980. Long-range atmospheric transport of soil dust from Asia to the tropical north Pacific: temporal variability. Science 209, 1522–1524. Handa, N., Ohta, K., 1983. Sedimentary record of polycyclic aromatic hydrocarbon pollution in Tokyo bay. Chikyukagaku (Geochemistry) 16, 60–67. Hovan, S.A., Rea, D.K., Pisias, N.G., 1991. Late pleistocene continental climate and oceanic variability recorded in northwest Pacific sediments. Paleoceanography 6, 349–370. Irino, T., Tada, R., 2000. Quantification of aeolian dust (Kosa) contribution to the Japan sea sediments and its variation during the last 200 ky. Geochemical Journal 34, 59–93. Ishizaka, Y., Ono, A., 1982. Mass size distribution of the principal minerals of yellow sand dust in the air over Japan. Idojaras 86, 249–253. Iwasaka, Y., Minoura, H., Nagaya, K., 1979. The transport and spacial scale of Asian dust–storm clouds: a case study of the dust–storm event of April. Tellus 35B, 189–196. Kadowaki, S., 1979. Silicon and aluminum in urban aerosols for characterization of atmospheric soil particles in the Nagoya area. Environmental Science and Technology 13, 1130–1133. Kawaguchiko Weather Station, Meteorological Agency of Japan: Monthly Summaries of 1970–2001. Kawahata, H., Okamoto, T., Matsumoto, E., Ujiie, H., 2000. Fluctuations of eolian flux and ocean productivity in the mid-latitude north Pacific during the last 200 kyr. Quaternary Science Reviews 19, 1279–1291. Kawakami, S., 1995. Shimashima-gaku: decording Earth’s evolution through Rhythm, University of Tokyo Press, Tokyo, pp. 126–144. Kobayashi, H., Koshimizu, S., Fukasawa, R., Kyotani, T., Uchiyama, T., Iwatsuki, M., 2000. Organic chemical analysis of sediment cores from Lake Kawaguchi in Yamanashi Prefecture, central Japan. Proceedings of the 10th Symposium on Geo-Environments and Geo-Technics, Tokyo, pp. 217–222. Kofu Weather Station, Meteorological Agency of Japan: Monthly Summaries of 1970–2001. Koshimizu, S., Uchiyama, T., Nagashima, M., Shibata, T., Yoshizawa, K., Kasai, M., Aoto, S., 1999. Stratigraphy and geological age of borehole core from lake Kawaguchi, central Japan. 106th Annual Meeting of the Geological Society of Japan (Abstract). p. 26. Kyotani, T., Koshimizu, S., 2001. Identification of individual Si-rich particles derived from Kosa aerosol by the alkali elemental composition. Bulletin of the Chemical Society of Japan 74, 723–729.
ARTICLE IN PRESS 3342
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Leinen, M., Heath, G.R., 1981. Sedimentary indicators of atmospheric activity in the northern hemisphere during the cenozoic. Palaeogeography, Palaeoclimatology, Palaeoecology 36, 1–21. Leinen, M., Prospero, J.M., Arnold, E., Blank, M., 1994. Mineralogy of aeolian dust reaching the north Pacific ocean 1. Sampling and analysis. Journal of Geophysical Research 99, 21,017–21,023. Merrill, J.T., Arnold, E., Leinen, M., Weaver, C., 1994. Mineralogy of aeolian dust reaching the north Pacific ocean 2. Relationship of mineral assemblages to atmospheric transport patterns. Journal of Geophysical Research 99, 21,025–21,032. Mizota, C., Matsuhisa, Y., 1985. Eolian additions to soil and sediments of Japan. Soil Science and Plant Nutrition 31, 369–382. Muller, G., Grimmer, G., Bohnke, H., 1977. Sedimentary record of heavy metals and polycyclic aromatic hydrocarbons in Lake Constance. Naturwissenschaften 64, 427–431. Nakai, S., Halliday, A.N., Rea, D.K., 1993. Provenance of dust in the Pacific Ocean. Earth and Planetary Science Letters 119, 143–157. Nishikawa, M., Kanamori, S., Kanamori, N., Mizoguchi, T., 1991. Kosa aerosol as eolian carrier of anthropogenic material. Science of the Total Environment 107, 13–27. Nishikawa, M., Morita, M., Mori, I., Tanimura, T., Quan, H., 2001. Typical Kosa aerosol caught in the network monitoring between Japan and China. Proceedings of 10th Symposium on Environmental Chemistry, Matsuyama, pp. 400–401. Okada, K., Naruse, H., Tanaka, T., Nemoto, O., Iwasaka, Y., Wu, P.-M., Ono, A., Duce, R.A., Uematsu, M., Merrill, J.T., Arao, K., 1990. X-ray spectrometry of individual Asian dust–storm particles over the Japanese islands and the
north Pacific ocean. Atmospheric Environment 24A, 1369–1378. Okamoto, T., Matsumoto, E., Kawahata, H., 1996. The fluctuation of eolian dust in the Northwest Pacific during past 150 kyr. In: Techno-Ocean’96 Organizing Committee (Eds.), Proceedings of Techno-Ocean’96 International Symposium. Kobe, Japan, pp. 323–327. Prahl, F.G., Carpenter, R., 1979. The role of zooplankton fecal pellets in the sedimentation of polycyclic aromatic hydrocarbons in Dabob bay, Washington. Geochimica et Cosmochimica Acta 43, 1959–1972. Ro, C.-U., Oh, K.-Y., Kim, H.K., Chun, Y., Osan, J., Hoog, J., Van Grieken, R., 2001. Chemical speciation of individual atmospheric particles using low-Z electron probe X-ray microanalysis: characterizing ‘‘Asian Dust’’ deposited with rain water in Seoul, Korea. Atmospheric Environment 35, 4995–5005. Syers, J.K., Mokma, D.L., Jackson, M.L., Dolcater, D.L., Rex, R.W., 1972. Mineralogical composition and cesium-137 retention properties of continental aerosolic dusts. Soil Science 113, 116–123. Uematsu, M., Duce, R.A., Prospero, J.M., Chen, L., Merrill, J.T., McDonald, R.L., 1983. Transport of mineral aerosol from Asia over the north Pacific ocean. Journal of Geophysical Research 88, 5343–5352. Uematsu, M., Kinoshita, K., Nojiri, Y., 2000. Scavenging of insoluble particles from the marine atmosphere over the sub-Arctic north Pacific. Journal of Atmospheric Chemistry 35, 151–164. Windom, H.L., 1975. Eolian contributions to marine sediments. Journal of Sedimentary Petroleum 45, 520–529. Xiao, J., Porter, S.C., An, Z., Kumai, H., Yoshikawa, S., 1995. Grain size of quartz as an indicator of winter monsoon strength on the loess Plateau of central China during the last 130,000 yr. Quaternary Research 43, 22–29.
Atmospheric Environment 39 (2005) 3335–3342 www.elsevier.com/locate/atmosenv
Short-term cycle of eolian dust (Kosa) recorded in Lake Kawaguchi sediments, central Japan Tomohiro Kyotania,b,d,, Satoshi Koshimizub, Hiroshi Kobayashic a Japan Science and Technology Corporation, 4-1-8, Honmachi, Kawaguchi, Saitama 332-0012, Japan Earth Science Division, Yamanashi Institute of Environmental Sciences, 5597-1, Kenmarubi, Kamiyoshida, Fujiyoshida, Yamanashi 403-0005, Japan c Yamanashi Institute for Public Health, 1-7-31, Fujimi, Kofu, Yamanashi 400-0027, Japan d Bussan Nanotech Research Institute Inc., Mitsui & Co., Ltd. Nanotech Park, 2-1, Koyadai, Tsukuba, Ibaraki 305-0074, Japan b
Received 29 June 2004; received in revised form 4 January 2005; accepted 4 January 2005
Abstract The fluctuation during the last 100 yr of the eolian dust (Kosa aerosol) originating from arid and semi-arid areas of China has been reconstructed by using the sediments from Lake Kawaguchi, central Japan with high temporal resolution. The quantification of Kosa contribution to the sediments was carried out by a new method using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX) proposed by us. The correlation plot of (Na2O+K2O) contents against SiO2 was used for individual Si-rich particles having SiO2 content over 80%. The Kosa fraction of Si-rich particles in Lake Kawaguchi sediments during the last 100 yr is approximately 10–30%. The fluctuation of the Kosa fraction during the last 100 yr does not coincide with that of the total amount of Si-rich particles, because detrital components from Japanese igneous rocks control the fluctuation of the total number of Sirich particles. The discrimination method based on single particle analysis is more effective than that of bulk analysis for the lake sediments formed by complex matrix components. We can first show a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation. Higher sedimentation rates (5–10 yr-cm) of the Lake Kawaguchi sediments and the new analytical method using SEM-EDX revealed a remarkable fluctuation pattern of Kosa aerosol, suggesting climate cycles much shorter than glacial–interglacial. Such short-term cycles may be related to sun-spots. The number of days of Kosa events during the last 30 yr, obtained by visual observation by Meteorological Agency of Japan, also supports the presence of such a short-term cycle. r 2005 Elsevier Ltd. All rights reserved. Keywords: Kosa aerosol; Si-rich particles; Short-term cycle; Climate change; Lake Kawaguchi sediment; SEM-EDX
1. Introduction The eolian dust, called the Kosa (yellow sand) aerosol (Kadowaki, 1979; Iwasaka et al., 1979; Nishikawa et al., Corresponding author. Bussan Nanotech Research Institute
Inc., Mitsui & Co., Ltd. Nanotech Park, 2-1, Koyadai, Tsukuba, Ibaraki 305-0074, Japan. Fax: +81 29 839 9430. E-mail address: [email protected] (T. Kyotani).
1991) in Japan, originating from arid and semi-arid areas of China and reaching as far as the north Pacific Ocean (Duce et al., 1980; Uematsu et al., 1983, 2000; Okada et al., 1990; Leinen et al., 1994), is an effective indicator of the aridity in the source area and of paleoclimate in eastern Asia. The past variation has been reconstructed using mainly marine sediment core samples as a course of research for the problem of global warming (Mizota and Matsuhisa, 1985; Hovan
1352-2310/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2005.01.026
ARTICLE IN PRESS 3336
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
et al., 1991; Okamoto et al., 1996; Irino and Tada, 2000; Kawahata et al., 2000). The Kosa flux varies significantly corresponding to glacial–interglacial cycles, with higher contribution during glacial periods and lower contribution during interglacial periods (Hovan et al., 1991; Irino and Tada, 2000; Kawahata et al., 2000). The presence of millennium-scale fluctuation of Kosa flux with a magnitude as large as that of Milankovitch-scale variation is also well known from the age profiles for marine sediments (Irino and Tada, 2000; Kawahata et al., 2000). The number of samples used to cover long time ranges such as the last 150–200 ky is normally 100–200 samples with intervals of approximately 1 ky (Irino and Tada, 2000; Kawahata et al., 2000). Therefore, since the time resolution in conventional age profiles of Kosa flux is usually low, periodic fluctuation patterns much shorter than glacial–interglacial cycles have not yet been detected. The use of lake sediments formed by the higher sedimentation rates is better for short time resolution analysis than that if marine sediments. Since the contribution of terrestrial materials other than eolian dust like Kosa is usually low for pelagic marine sediments such as the Pacific Ocean (Syers et al., 1972; Windom, 1975; Duce et al., 1980; Leinen and Heath, 1981; Blank et al., 1985; Nakai et al., 1993; Leinen et al., 1994; Merrill et al., 1994), the quantification of Kosa contribution to such marine sediments has been carried out successfully on the basis of bulk chemical and mineralogical analysis, for example of quartz (Irino and Tada, 2000; Kawahata et al., 2000), aluminum (Duce et al., 1980; Uematsu et al., 1983; Kawahata et al., 2000), etc. On the other hand, lake sediments located in an inland area should be strongly affected by the surrounding environment. Therefore, it is difficult to discriminate the Kosa particles of small or trace amounts in lake sediments using bulk analysis that gives information only for average compositions. Thus, the methods for the identification and quantification of Kosa particles in lake sediments formed by complex matrix components have not yet been established. In this study, we proposed a new method for the identification of individual Kosa particles using scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EDX). Here, we have identified and quantified grain by grain Si-rich particles derived from Kosa aerosol in sediments from Lake Kawaguchi, Central Japan, and found the fluctuation during the last 100 yr with short time resolution. Consequently, a short-term (approximately 10–20 yr scale) cycle in Kosa aerosol fluctuation was first discussed.
2. Study area and sediment core samples Lake Kawaguchi is located at the northern foot of Mt. Fuji, Yamanashi Prefecture, central Japan (351
310 N, 1381 460 E). The detail of the sampling location is shown in Fig. 1. The stratigraphy and geological age of 90 m borehole core from Lake Kawaguchi were already reported (Koshimizu et al., 1999); the sedimentation rates of the silt beds are approximately 5–10 yr-cm. Samples used in this study are a silt bed up to 20 cm in depth from the top of the sediment core at Lake Kawaguchi and were cut every 1 cm. As shown in Fig. 2, age-control in the samples was also confirmed by the depth profile of polycyclic aromatic hydrocarbons (PAHs) concentrations (Kobayashi et al., 2000). It has been well known that the emission into the environment of PAHs increased suddenly in the last 100 yr and the maximum point in the depth profile of PAHs concentrations corresponds to 1970–1960 (Muller et al., 1977; Prahl and Carpenter, 1979; Handa and Ohta, 1983; Cranwell and Koul, 1989). The depth profile of total concentration of PAHs up to 20 cm in Lake Kawaguchi sediments showed the maximum values at 8–9 and 9–10 cm depths (Kobayashi et al., 2000). Therefore, judging from both the geological age of the 90 m borehole core (Koshimizu et al., 1999) and the PAHs profile (Kobayashi et al., 2000) in the surface layer, the sedimentation rates up to 20 cm depth could be estimated to be approximately 5–10 yr-cm, although the rates in the last 30–40 yr seem to be high (3–5 yr-cm). Consequently, 20 cm overall covers the last 100 yr.
3. Methods 3.1. Si-rich particles as an effective indicator of Kosa aerosol We have already described a new method of SEMEDX for the identification of individual Kosa particles in atmospheric aerosol with the size below 10 mm (Kyotani and Koshimizu, 2001). Si-rich particles (mainly quartz) having SiO2 content over 80% can be used as an effective indicator in this region. The correlation plot between (Na2O+K2O) and SiO2 contents in individual Si-rich particles from atmospheric aerosol, determined grain by grain, by SEM-EDX using a standardless f(rz) correction program, shows a sharp and clear seasonal variation (Fig. 3). Furthermore, the distribution in spring time concentrates in a specific area, and is closer to those in the China loess and desert sand compared to non-Kosa aerosol (Figs. 3 and 4). Although the source region in China of Kosa aerosol is so wide, the distribution area of real Kosa aerosol observed in Japan is quite narrow and is fixed. The observation fact is the greatest reason for the determination of the Kosa area. Therefore, two source materials (loess CJ-1 and desert sand CJ-2) of Kosa were used not to determine the Kosa area but to compare with the
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3337
Fig. 1. Five lakes at the northern foot of Mt. Fuji, central Japan and the sampling site.
distribution area of real Kosa aerosol observed in Japan (Figs. 3 and 4). Thus, individual Si-rich particles derived from Kosa aerosol can be clearly discriminated from the Japanese igneous rocks by differences of the distribution areas of (Na2O+K2O)/SiO2. 3.2. Quantification of Kosa contribution to lake sediments The identification method described above was applied to the Lake Kawaguchi sediments, and the quantification of Kosa contribution was carried out by counting the number of individual Kosa particles in each sample. The core samples contained a large quantity of organic materials. Prior to SEM-EDX analysis, each sample was converted to the specimen suitable for single particle analysis. At first, the sediment core samples were dried at 110 1C for 2 h. 0.5 g of the dried and powdered sample was ignited at 1000 1C for 6 h, and 0.5–1.0 mg of the ignited sample was washed in a 10 ml volume of 6 N hydrochloric acid for 20 min by ultrasonication. The residual particles were filtered off through a 0.45 mm membrane filter, and washing with 3 ml of water was repeated 5 times to remove any hydrochloric acid from the particles on the filter. After drying for 30 min at 110 1C, the particles on
the filters were detached by double-sided adhesive carbon tape and were fixed on the aluminum sample stands (15 mm in diameter, 5 mm in height) for SEM-EDX. Thereafter, the particles were carbon coated (200 A˚) and the specimens were subjected to the SEM-EDX analysis. The details of the experimental conditions for SEM-EDX analysis have been described elsewhere (Kyotani and Koshimizu, 2001). It was confirmed that the evaporation of alkaline elements from Si-rich particles and the contamination from coexisting organic matters can be neglected during the ignition procedure. Namely, these procedures do not affect the distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles. This shows that Si-rich particles are composed of extremely stable components, that is, quartz. About 200 mineral grains with the size below 10 mm in the residues were analyzed by SEM-EDX for each sample, and the distribution areas of (Na2O+K2O)/SiO2 for individual Si-rich particles were evaluated likewise in the case of atmospheric aerosol as shown in Figs. 3 and 4 (Kyotani and Koshimizu, 2001). Fig. 5 shows an example of the distribution of (Na2O+K2O)/SiO2 for individual Si-rich particles from the Lake Kawaguchi sediment. The distribution area of individual Si-rich particles derived
ARTICLE IN PRESS 3338
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Fig. 2. Fluctuation of polycyclic aromatic hydrocarbons (PAHs) concentrations in Lake Kawaguchi sediments, central Japan. This figure was illustrated using the data of Kobayashi et al., 2000.
from Kosa confirmed for real atmospheric aerosol (Kyotani and Koshimizu, 2001) is drawn using an oblique line. Si-rich particles found in this specific area (Kosa area) were regarded as the Kosa particles. Other Si-rich particles are mainly from Japanese igneous rocks. The particles from Japanese igneous rocks, fallen into the area where both sodium and potassium were not detected, are mainly background particles in the northern foot of Mt. Fuji (Kyotani and Koshimizu, 2001). The background particles may be mainly derived from Misaka mountains composed of pyroclastic and volcanic rocks located at the northern region of Lake Kawaguchi. The Kosa fraction was calculated as the relative ratio of the number of Si-rich particles found in the Kosa area to the total number of Sirich particles in the samples. The content of Si-rich particles was calculated as the relative ratio of the total number of Si-rich particles to the total number of mineral particles measured in the samples. Fig. 3. Seasonal variation of the distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles from atmospheric aerosol collected at Kofu Basin that is mainly granitic and sedimentary. Each point expresses an individual particle. Lines indicate the distribution areas of granodiorite (JG-1a), andesite (JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). This figure was illustrated using the data of Kyotani and Koshimizu, 2001.
4. Results and discussion 4.1. Kosa fraction of Si-rich particles quantified by the present method The discrimination of Kosa particles based on the shape and grain size of minerals has often been done; it
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3339
Fig. 4. Distribution area of (Na2O+K2O)/SiO2 in individual Si-rich particles from atmospheric aerosol collected at the northern foot of Mt. Fuji that is mainly basaltic. Each point expresses an individual particle. Lines indicate the distribution areas of granodiorite (JG-1a), andesite (JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). This figure was illustrated using the data of Kyotani and Koshimizu, 2001.
has been reported that continental soil is relatively round quartz (Xiao et al., 1995; Okamoto et al., 1996; Kawahata et al., 2000) and the grain size of Kosa aerosol reaching Japan is mostly several microns (Kadowaki, 1979; Okada et al, 1990; Nishikawa et al., 1991). However, the application of this discrimination to lake sediments is difficult, because detrital particles from Japanese igneous rocks have shape and grain size characteristics similar to Kosa. Although eolian dust particles under Kosa phenomena include many minerals other than Si-rich particles (Ishizaka and Ono, 1982; Okada et al., 1990; Uematsu et al., 2000; Ro et al., 2001), the indicator available for paleo-environment analysis should be limited to minerals having high chemical stability. Si-rich particles mainly composed of quartz (Kyotani and Koshimizu, 2001) seem to be the best indicator for paleo-environment analysis. On the other hand, easily weathering minerals such as alkali feldspars, plagioclase, clay minerals, etc. are not suitable to the aim. Furthermore, the basaltic geology around Mt. Fuji originating from eruptive materials containing low percentages of quartz provides a lower background for the Si-rich particle discrimination in the present study than do other granitic or sedimentary regions (Kyotani and Koshimizu, 2001). Judging from these points, the chemical composition of individual Si-rich
particles was used as an indicator for paleo-climate analysis in Lake Kawaguchi sediments. Fig. 6 shows the fluctuations of the total number of Si-rich particles (a) and the Kosa fraction (b) during the last 100 yr. The Kosa fraction of Si-rich particles is approximately 10–30% except for 16–17 cm depth. Therefore, detrital components from Japanese igneous rocks affect essentially the total number of Si-rich particles in the Lake Kawaguchi sediments. This result indicates that the method based on single particle analysis is more effective for the lake sediments formed by the complex matrix components than bulk analysis. Bulk analysis using average compositions will not provide such a fractional contribution. 4.2. Short-term variation of Kosa aerosol The depth profile of the total number of Si-rich particles (Fig. 6a) differed from that of the Kosa fraction (Fig. 6b) during the last 100 yr, although both of them coincide between 15 and 20 cm. The total number of Sirich particles (Fig. 6a) has gradually increased during the last 100 yr, except for 16–17 cm where the large input of Kosa aerosol to the lake is recognized. The large input at 1–2 cm depth is mainly attributed to Japanese Si-rich particles. On the other hand, the Kosa fraction
ARTICLE IN PRESS 3340
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Fig. 5. Example of the distribution of (Na2O+K2O)/SiO2 in individual Si-rich particles from the sediment core (depth:1–2 cm) at Lake Kawaguchi, central Japan. Each point expresses an individual particle. Lines indicate the examples of distribution areas (Kyotani and Koshimizu, 2001) in individual Si-rich particles from Japanese igneous rocks (granodiorite JG-1a, andesite JA-1), China loess (CJ-1) and Tengger desert sand (CJ-2). Kosa fraction (%) ¼ NKosa/ NSi 100; content of Si-rich particles (%) ¼ NSi/Nmi 100 (NKosa: the number of Si-rich particles found in the Kosa area; NSi: total number of Si-rich particles; Nmi: total number of mineral particles measured in the samples).
(Fig. 6b) has gradually decreased during the last 100 yr in spite of the recent desertification in China. It can be judged from the distribution areas of (Na2O+K2O)/ SiO2 in Fig. 5 that the present Kosa aerosol is mainly not from loess but from desert sand which is characterized by its relatively low content of SiO2. The Kosa fraction shows a clear fluctuation cycle corresponding to approximately 10–20 yr scale, since 1 cm sample contains 5–10 yr accumulation. Even if the Kosa fraction is a part of total flux, the result as shown in Fig. 6b is the first datum that shows the possibility of a short periodic cycle. The cycle becomes slightly shorter from the 10 cm depth (1970–1960) downward to the present. A 10-yr scale cycle has been observed in many other phenomena and the presence of climate change cycles at these extremely short time scales has been suggested (Kawakami, 1995 and references therein). These short time scale cycles were not observed in the marine sediments in the northwest Pacific Ocean (Kawahata et al., 2000; Okamoto et al., 1996) or the Japan Sea (Irino and Tada, 2000) which had extremely slow sedimentation rates. The higher sedimentation rates (Koshimizu et al., 1999; Kobayashi et al., 2000) of Lake Kawaguchi sediments and the new method first
Fig. 6. Fluctuations of the content of Si-rich particles (a) and the Kosa fraction (b) in Lake Kawaguchi sediments, central Japan during the last 100 yr. PAHs concentrations and the depth profile, see Fig. 2.
detected the remarkable fluctuation pattern of Kosa aerosol. As reference data, Fig. 7 shows the fluctuation in the number of days of Kosa events by year obtained by visual observation at 2 observatories (Lake Kawaguchi and Kofu City) in Yamanashi Prefecture from 1970 to 2001 (Kawaguchiko and Kofu Weather Stations, Meteorological Agency of Japan, 1970–2001). Although the visual monitoring data of Kosa aerosol observed at weather stations, Meteorological Agency of Japan has been partly compiled, the discussion has been done concentrating not on the fluctuation cycle but on the increase of Kosa events in the past 1–2 yr (Nishikawa et al., 2001). Fig. 7 shows clearly that the peak has appeared at an interval of about 10–13 yr and the number of days observed has gradually decreased during the last 30 yr. In this study, a certain relationship between the number of days of Kosa events and total Kosa flux is not clarified. Also, since the time resolution of our data in Fig. 6b is 5–10 yr accumulation and the observation period in Fig. 7 is only 30 yr, direct comparison among them may be difficult. But, the observation fact in Fig. 7 is important data which support the possibility of short-term variation such as 10-yr scale found by us. The 11 yr cycle is also observed on solar variability (Kawakami, 1995 and references therein). The
ARTICLE IN PRESS T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
3341
higher sedimentation rates and the new SEM-EDX method.
References
Fig. 7. Fluctuation in the number of days of Kosa events by year obtained by visual observation at 2 observatories (Lake Kawaguchi and Kofu City) in Yamanashi Prefecture from 1970 to 2001. This figure was compiled from the Monthly Summaries (1970–2001) of Kawaguchiko and Kofu weather stations, Meteorological Agency of Japan.
short-term fluctuation cycle of the Kosa fraction found in the lake sediments may relate to these climatic phenomena.
5. Conclusions Our measurement of individual Si-rich particles from Lake Kawaguchi sediments, central Japan lead to the following conclusions: (1) Grain by grain analysis was effective to determine the Kosa contribution in lake sediments. In this study, individual Si-rich particles derived from Kosa aerosol in the lake sediments could be identified and quantified successfully by using the distribution area of (Na2O+K2O)/SiO2 determined by SEM-EDX. (2) The Kosa fraction of Si-rich particles in the Lake Kawaguchi sediments during the last 100 yr is approximately 10–30% and does not coincide with fluctuation of the total amount of Si-rich particles. Detrital components from Japanese igneous rocks, being the major matrix, control essentially the fluctuation of the total number of Si-rich particles in the sediments. (3) The Kosa fraction of Si-rich particles shows a shortterm fluctuation cycle which corresponds to approximately 10–20 yr scale. Although the Kosa fraction is a part of total flux, the possibility of presence of the periodic fluctuation cycle much shorter than glacial–interglacial was first shown for Kosa aerosol by using both the Lake Kawaguchi sediments with
Blank, M., Leinen, M., Prospero, J.M., 1985. Major Asian aeolian inputs indicated by the mineralogy of aerosoles and sediments in the western North Pacific. Nature 314, 84–86. Cranwell, P.A., Koul, V.K., 1989. Sedimentary record of polycyclic aromatic and aliphatic hydrocarbons in the Windermere Catchment. Water Research 23, 275–283. Duce, R.A., Unni, C.K., Ray, B.J., Prospero, J.M., Merrill, J.T., 1980. Long-range atmospheric transport of soil dust from Asia to the tropical north Pacific: temporal variability. Science 209, 1522–1524. Handa, N., Ohta, K., 1983. Sedimentary record of polycyclic aromatic hydrocarbon pollution in Tokyo bay. Chikyukagaku (Geochemistry) 16, 60–67. Hovan, S.A., Rea, D.K., Pisias, N.G., 1991. Late pleistocene continental climate and oceanic variability recorded in northwest Pacific sediments. Paleoceanography 6, 349–370. Irino, T., Tada, R., 2000. Quantification of aeolian dust (Kosa) contribution to the Japan sea sediments and its variation during the last 200 ky. Geochemical Journal 34, 59–93. Ishizaka, Y., Ono, A., 1982. Mass size distribution of the principal minerals of yellow sand dust in the air over Japan. Idojaras 86, 249–253. Iwasaka, Y., Minoura, H., Nagaya, K., 1979. The transport and spacial scale of Asian dust–storm clouds: a case study of the dust–storm event of April. Tellus 35B, 189–196. Kadowaki, S., 1979. Silicon and aluminum in urban aerosols for characterization of atmospheric soil particles in the Nagoya area. Environmental Science and Technology 13, 1130–1133. Kawaguchiko Weather Station, Meteorological Agency of Japan: Monthly Summaries of 1970–2001. Kawahata, H., Okamoto, T., Matsumoto, E., Ujiie, H., 2000. Fluctuations of eolian flux and ocean productivity in the mid-latitude north Pacific during the last 200 kyr. Quaternary Science Reviews 19, 1279–1291. Kawakami, S., 1995. Shimashima-gaku: decording Earth’s evolution through Rhythm, University of Tokyo Press, Tokyo, pp. 126–144. Kobayashi, H., Koshimizu, S., Fukasawa, R., Kyotani, T., Uchiyama, T., Iwatsuki, M., 2000. Organic chemical analysis of sediment cores from Lake Kawaguchi in Yamanashi Prefecture, central Japan. Proceedings of the 10th Symposium on Geo-Environments and Geo-Technics, Tokyo, pp. 217–222. Kofu Weather Station, Meteorological Agency of Japan: Monthly Summaries of 1970–2001. Koshimizu, S., Uchiyama, T., Nagashima, M., Shibata, T., Yoshizawa, K., Kasai, M., Aoto, S., 1999. Stratigraphy and geological age of borehole core from lake Kawaguchi, central Japan. 106th Annual Meeting of the Geological Society of Japan (Abstract). p. 26. Kyotani, T., Koshimizu, S., 2001. Identification of individual Si-rich particles derived from Kosa aerosol by the alkali elemental composition. Bulletin of the Chemical Society of Japan 74, 723–729.
ARTICLE IN PRESS 3342
T. Kyotani et al. / Atmospheric Environment 39 (2005) 3335–3342
Leinen, M., Heath, G.R., 1981. Sedimentary indicators of atmospheric activity in the northern hemisphere during the cenozoic. Palaeogeography, Palaeoclimatology, Palaeoecology 36, 1–21. Leinen, M., Prospero, J.M., Arnold, E., Blank, M., 1994. Mineralogy of aeolian dust reaching the north Pacific ocean 1. Sampling and analysis. Journal of Geophysical Research 99, 21,017–21,023. Merrill, J.T., Arnold, E., Leinen, M., Weaver, C., 1994. Mineralogy of aeolian dust reaching the north Pacific ocean 2. Relationship of mineral assemblages to atmospheric transport patterns. Journal of Geophysical Research 99, 21,025–21,032. Mizota, C., Matsuhisa, Y., 1985. Eolian additions to soil and sediments of Japan. Soil Science and Plant Nutrition 31, 369–382. Muller, G., Grimmer, G., Bohnke, H., 1977. Sedimentary record of heavy metals and polycyclic aromatic hydrocarbons in Lake Constance. Naturwissenschaften 64, 427–431. Nakai, S., Halliday, A.N., Rea, D.K., 1993. Provenance of dust in the Pacific Ocean. Earth and Planetary Science Letters 119, 143–157. Nishikawa, M., Kanamori, S., Kanamori, N., Mizoguchi, T., 1991. Kosa aerosol as eolian carrier of anthropogenic material. Science of the Total Environment 107, 13–27. Nishikawa, M., Morita, M., Mori, I., Tanimura, T., Quan, H., 2001. Typical Kosa aerosol caught in the network monitoring between Japan and China. Proceedings of 10th Symposium on Environmental Chemistry, Matsuyama, pp. 400–401. Okada, K., Naruse, H., Tanaka, T., Nemoto, O., Iwasaka, Y., Wu, P.-M., Ono, A., Duce, R.A., Uematsu, M., Merrill, J.T., Arao, K., 1990. X-ray spectrometry of individual Asian dust–storm particles over the Japanese islands and the
north Pacific ocean. Atmospheric Environment 24A, 1369–1378. Okamoto, T., Matsumoto, E., Kawahata, H., 1996. The fluctuation of eolian dust in the Northwest Pacific during past 150 kyr. In: Techno-Ocean’96 Organizing Committee (Eds.), Proceedings of Techno-Ocean’96 International Symposium. Kobe, Japan, pp. 323–327. Prahl, F.G., Carpenter, R., 1979. The role of zooplankton fecal pellets in the sedimentation of polycyclic aromatic hydrocarbons in Dabob bay, Washington. Geochimica et Cosmochimica Acta 43, 1959–1972. Ro, C.-U., Oh, K.-Y., Kim, H.K., Chun, Y., Osan, J., Hoog, J., Van Grieken, R., 2001. Chemical speciation of individual atmospheric particles using low-Z electron probe X-ray microanalysis: characterizing ‘‘Asian Dust’’ deposited with rain water in Seoul, Korea. Atmospheric Environment 35, 4995–5005. Syers, J.K., Mokma, D.L., Jackson, M.L., Dolcater, D.L., Rex, R.W., 1972. Mineralogical composition and cesium-137 retention properties of continental aerosolic dusts. Soil Science 113, 116–123. Uematsu, M., Duce, R.A., Prospero, J.M., Chen, L., Merrill, J.T., McDonald, R.L., 1983. Transport of mineral aerosol from Asia over the north Pacific ocean. Journal of Geophysical Research 88, 5343–5352. Uematsu, M., Kinoshita, K., Nojiri, Y., 2000. Scavenging of insoluble particles from the marine atmosphere over the sub-Arctic north Pacific. Journal of Atmospheric Chemistry 35, 151–164. Windom, H.L., 1975. Eolian contributions to marine sediments. Journal of Sedimentary Petroleum 45, 520–529. Xiao, J., Porter, S.C., An, Z., Kumai, H., Yoshikawa, S., 1995. Grain size of quartz as an indicator of winter monsoon strength on the loess Plateau of central China during the last 130,000 yr. Quaternary Research 43, 22–29.