Chinese Continent Research Articles

The important turning points during evolution of Cenozoic basin offshore the Bohai Sea: Evidence and regional dynamics analysis

The Cenozoic basin offshore the Bohai Sea underwent a multicycle-rifting during its evolutionary process, which resulted in the multiple unconformities in the strata. The tectonic activities shown by these unconformities have different manifestations and influences on the basin evolution. The authors systematically analyze the tectonic evolution characteristics of the sags offshore the Bohai Sea with a large set of hydrocarbon exploration data. The analysis reveals that two phases of tectonic activities during the late depositional stage of the third member of Shahejie Formation (about 38 Ma) and the late depositional stage of Dongying Formation (about 24 Ma) reflect the significant changes in the basin’s features and structural framework before and after these tectonic activities. As a result, the two phases of tectonic activities are recognized as important turning points (i.e., tectonic transitions) of Cenozoic basin evolution. The regional dynamic backgrounds of the two phases of tectonic transitions are also discussed. It is suggested that the early tectonic transition occurred at about 38 Ma under such regional dynamic background that a huge kinematics adjustment happened between Eurasian Plate and its neighboring plates, i.e., Pacific Plate and Indian Plate. Meanwhile, the Tan-Lu Fault’s slip reversed from left lateral to right lateral. The late tectonic transition occurred in late Paleogene (about 24 Ma) and reflected the Himalayan orogeny’s influence on the Chinese continent and even the Asian continent; at the same time, the stress field produced by the escape tectonics was related to the Himalayan orogeny, superposed on the pre-existing stress field, and then enhanced the right lateral slip activity of the Tan-Lu Fault.

Migration trend of strong earthquakes in North China from numerical simulations

Lu et al. (2011) established a finite element model around the entire Chinese continent to simulate the distant migration of strong earthquakes by killing the elements. In this study a new finite element model of North China has been established in the existing Chinese continental model using the GPS observations and the finite element sub-model technique through taking into account geological structure, active faults, surface topography, Moho discontinuity and 3-D velocity structure of the crust and upper mantle in the region. Furthermore, the stress field adjustment was realized by reducing the element stiffness rather than by killing the elements. We calculated the displacement of the Chinese continent model, and took the displacement located at the boundary of North China as the boundary loadings, then computed the initial stress field by considering the gravity effect. The migration of the strong earthquake regions was simulated by performing a number of tests with various kinds of short-term boundary loadings. Locations of strong earthquakes were determined with the highest G (the risk factor of the fault) value and adjustment of the stress field. Our results showed that high stress disturbance regions could be possible regions of future strong earthquakes, and that the initial stress field in North China can be well estimated, if an optimal boundary loading configuration is chosen in the Chinese continental model. These results suggest that the strong earthquake forecast in North China may strongly depend on the stress field and strong earthquake activities in a much wider area, such as the Chinese continent.

Genetic variation of the white-spotted longicorn beetle Anoplophora spp. (Coleoptera: Cerambycidae) in Japan detected by mitochondrial DNA sequence

Genetic variation of the white-spotted longicorn beetle Anoplophora spp., distributed on the Japanese mainland and the Ryukyu Islands, was examined using nucleotide sequences of mitochondrial DNA. Two fragments, a 1.2-kb-long fragment containing portions of the cytochrome oxidase subunit I and II genes and a 1.4-kb-long fragment containing portions of 16S and 12S rDNAs, were sequenced. In phylogenetic analyses based on the sequences, 294 individuals collected at 75 localities were divided into two major groups (groups A and B) and then split into seven subgroups (A1–A4 and B1–B3). In group A, the closely related subgroups A1, A2, and A3 were mainly distributed on the Japanese mainland and were roughly separated among geographic areas, although the range of A3 spread significantly from Kyushu to the Central Ryukyu Islands. The sequence of A4, detected from one individual collected in eastern Honshu, was almost the same as that reported for A. chinensis (Forster) on the Chinese continent. In group B, subgroups B1 and B2 were restricted to the Central and Southern Ryukyu Islands, respectively, while B3 was distributed widely in both regions. Based on the results, we discuss the geographic origin of the haplotypes and movement of the insects between geographic areas.

Petrology, geochemistry, and tectonic significance of Mesozoic shoshonitic volcanic rocks, Luzong volcanic basin, eastern China

We studied the geochemical characteristics of three types of Mesozoic igneous rocks from the Luzong volcanic basin: basaltic trachyandesite at Shuangmiao, pyroxene monzonite at Bajiatan, and quartz-syenite (A-type granite) at Huangmeijian. Based on analyses of whole-rock major elements, all investigated rocks are enriched in K, Na, Ti, Al, but depleted in Ca, representing a shoshonitic series. Trace element analyses show that these rocks are characterized by enrichments of large-ion lithophile elements and high field strength elements. Positive Nb and Ta anomalies in the chondrite-normalized spider diagram indicate that the shoshonitic volcanic rocks share similar features with Nb-enriched basalts, which are different from normal island-arc volcanical rocks (they are typically strongly depleted in Nb and Ta). Bulk-rock chemical compositions and Sr–Nd isotopes indicate that the three types of igneous rocks are geochemically comagmatic, suggesting that the melts were derived from an enriched mantle reservoir. We postulate an extensional tectonic setting for the formation of Luzong volcanic basin, possibly related to subduction of a palaeo-Pacific plate beneath the east Chinese continent during the Yanshanian period (Cretaceous). Therefore, the petrogenetic features of those volcanic rocks as well as A-type granites in the Luzong basin indicate that the regional large-scale Fe–Cu–Au mineralization was associated with oceanic slab melting, but not delamination or recycling of the ancient lower continental crust, as previously proposed.

Chinese Continental Blocks in Global Paleocontinental Reconstruction during Paleozoic and Mesozoic

Abstract:The Cambrian to Cretaceous paleomagnetic data from Chinese continental and adjacent blocks were collected using principles to obtain reliable and high‐precision paleomagnetic data and to pay attention to the similarity of paleobiogeography and the coordination of tectonic evolution. The Chinese continental blocks were laid up on the reconstruction of proposed global paleocontinents with almost the same scale. Thus, it can be clearly recognized that the global continents, including Chinese continental blocks, range along latitudes on the southern side of the equator during the Early Paleozoic. In the Paleozoic, Chinese continental blocks were still located among the Laurentia, Siberia and Gondwana plates, following the fast moving of the Siberia Plate northwards, the amalgamation in a north‐south direction at the western parts of the Laurentia and Gondwana plates, and the Iapetus and Rheic Oceans were subducted, eventually to form a uniform Pangea in the Late Paleozoic. The Australian and Indian plates of Eastern Gondwana moved and dispersed gradually southwards, continued to extend the Paleo‐Tethys Ocean. The Chinese continental and adjacent blocks were still located in the Paleo‐Tethys Ocean, preserved the status of dispersion, gradually moving northwards, showing characteristics of ranging along a north–south orientation until the Permian. In addition, a series of local collisions happened during the Triassic, and consequently most of the Chinese continental blocks were amalgamated into the Pangea, except for the Gangdise and Himalayan blocks. There was a counter‐clockwise rotation of the Eastern Asian continent in the Jurassic and northwards migration of the Chinese continent in varying degrees during the Cretaceous, but the Himalayan and Indian plates did not collide into the Chinese continent during this period.

제주도 고산지역 TSP, PM2.5 대기에어로졸의 조성 및 오염 특성

제주도 고산지역에서 TSP (total suspended particulate), PM2.5 (particulate matter, below <TEX>$2.5\;{\mu}m$</TEX> particle size) 대기에어로졸을 채취, 분석하여 에어로졸의 조성과 오염 특성을 조사하였다. 고산지역 대기에어로졸에서 nss(non-sea salt)-<TEX>$SO_4^{2-}$</TEX>과 <TEX>$NH_4^+$</TEX>은 다른 국내 청정지역 및 도시지역에 비해 높은 조성비를보이고 <TEX>$NO_3^-$</TEX>는 상대적으로 낮은 조성비를 나타내었다. 에어로졸 성분의 입경별 분포를 비교해 본 결과, 인위적 기원의 nss-<TEX>$SO_4^{2-}$</TEX>, <TEX>$NO3_^-$</TEX>, <TEX>$NH_4^+$</TEX> 성분들은 대체적으로 미세입자에, 토양기원의 nss-<TEX>$Ca^{2+}$</TEX>과 해염기원의 <TEX>$Na^+$</TEX>, <TEX>$Cl^-$</TEX>, <TEX>$Mg^{2+}$</TEX>은 상대적으로 조대입자에 많이 분포하고 있는 것으로 확인되었다. 계절별로는 봄철에 nss-<TEX>$Ca^{2+}$</TEX>, Al, Fe, Ca, <TEX>$NO_3^-$</TEX> 성분의 농도가 크게 상승하고, nss-<TEX>$SO_4^{2-}$</TEX>은 여름과 봄철에 높은 농도를 나타내었다. 인자분석 결과, 에어로졸은 대체적으로 인위적 발생원의 영향을 많이 받고, 다음으로 해양 및 토양 영향을 많이 받았다. 또한 역궤적 분석법으로 에어로졸 성분의 유입경로를 조사해 본 결과, nss-<TEX>$SO_4^{2-}$</TEX>, <TEX>$NO_3^-$</TEX>, Pb, nss-<TEX>$Ca^{2+}$</TEX> 성분들은 대체적으로 기류가 중국대륙으로부터 제주지역으로 이동할 때 훨씬 더 높은 농도를 나타낸 반면, 북태평양에서 제주지역으로 이동할 때 상대적으로 낮은 농도를 나타내었다. TSP and PM2.5 atmospheric aerosols have been collected at Gosan site of Jeju Island, and their compositions were analyzed to understand the pollution characteristics. The composition ratios of nss (non-sea salt)-<TEX>$SO_4^{2-}$</TEX> and <TEX>$NH_4^+$</TEX> were higher in Gosan site than those in other Korean background and urban sites. However the composition ratio of <TEX>$NO_3^-$</TEX> was conversely lower in Gosan site. From the study of aerosol components according to particle sizes, the anthropogenic nss-<TEX>$SO_4^{2-}$</TEX>, <TEX>$NO_3^-$</TEX> and <TEX>$NH_4^+$</TEX> components were mostly existed in the fine particles. But the nss-<TEX>$Ca^{2+}$</TEX>, <TEX>$Na^+$</TEX>, <TEX>$Cl^-$</TEX> and <TEX>$Mg^{2+}$</TEX> originated from soil and marine sources were distributed relatively in the coarse particles. In the seasonal comparison, the concentrations of nss-<TEX>$Ca^{2+}$</TEX>, Al, Fe, Ca and <TEX>$NO_3^-$</TEX> increased in spring season, and nss-<TEX>$SO_4^{2-}$</TEX> showed higher concentration in summer and spring seasons. Based on the factor analysis, the atmospheric aerosols in Gosan site have been found to be influenced largely by anthropogenic sources, and next by marine and soil sources. The backward trajectory analyses showed that the concentrations of nss-<TEX>$SO_4^{2-}$</TEX>, <TEX>$NO_3^-$</TEX>, Pb and nss-<TEX>$Ca^{2+}$</TEX> increased when the air mass moved from Chinese continent to Jeju area. On the other hand, their concentrations decreased when the air mass moved in from the North Pacific Ocean.

Mechanism of the spatial distribution and migration of the strong earthquakes in China inferred from numerical simulation

Strong earthquakes that occurred in the Chinese continent are usually characterized by grouped activity, long-distance jumping migration, and different main activity areas formed in different times. In the present study, a three-dimensional (3-D) finite element model was set up for the Chinese continent involving surface topography, major active fault zones and initial stress field to study the mechanism of the long-distance jumping migration of main active areas for the strong earthquakes that occurred in the Chinese continent. A number of numerical simulation experiments have been made by introducing the birth and death of element groups under different boundary loading configurations. Our results show that (1) in an environment where always exists an initial stress field in the Earth’s crust, the areas where strong earthquakes have occurred (taken as a killed element in the model) have no longer abilities to concentrate the stress largely enough and can cause the stress adjustment by an order of MPa in a large area, which may be one of the main factors affecting the long-distance jumping migration of the follow-up strong earthquakes, and (2) it is hard to accurately predict where the follow-up strong-earthquakes will occur because it could be affected by many factors such as the loading manner, geological structure, active fault zones, initial stress field, or stress field adjustment induced by strong earthquakes, but in an active period of earthquakes, the major activity area migration of strong earthquakes may be affected largely by the boundary loading configurations. These results suggest that it is helpful to predict a trend of the strong earthquake migration by investigating various kinds of boundary loading manners and the relationship between stress field adjustment induced by strong earthquakes and the regions where the strong earthquakes occurred.

Estimation of GPS strain rate and its error analysis in the Chinese continent

In this paper we first estimate the strain rate field with 1202 GPS vectors from 1999 to 2005 in the Chinese continent. Then we propose a method to make error analysis of the strain rates computed from GPS vectors based on the Monte Carlo technique. In general, the orientations of compressive principal strain rates are in agreement with those of present tectonic stresses. The strain rates in the paper confirm the tectonic features of Tibetan Plateau such as NE–W compression and shortening, E–W extension, and normal faulting along near N–S faults. At the same time, the eastward extrusion in the east part of Tibet can also be seen from the strain rate field. In the error analysis, independent computation of strain rates is repeated for a large number of times, both the absolute and relative errors as well as the mean value of strain rates are obtained through statistical theory. The error result shows that the errors of strain rates may be associated with the uncertainties of GPS measurement and the distribution of GPS stations in space. The magnitude of the strain rate error is in the range of 3–8 × 10 −9/yr across China in general. However, we found that the relative errors are much larger in East China than those in the west of China. In addition, the relative errors of maximum shear strain rates are smaller than those of surface dilation rates. Also, we found that there may be some correlations between maximum shear strain rates and seismic activities. Where the maximum shear strain rates are higher, there the earthquakes occur more frequently. The computed GPS strain rates reveal the distributed nature of deformation across the whole Chinese continent, and can represent the main present-day tectonic features. The strain rate and its error in the paper may provide important constraints to geodynamical modeling.

Multiple origins of Locusta migratoria (Orthoptera: Acrididae) in the Japanese Archipelago and the presence of two major clades in the world: evidence from a molecular approach

Phylogenetic relationships among migratory locust (Locusta migratoria) populations in different climatic regions were analysed by sequencing four mitochondrial DNA regions, with special reference to the origin of Japanese populations. The populations are clearly separated into two clades: one consists of individuals from temperate and cold-temperate areas of Japan and the Chinese continent, and the other comprises those from subtropical islands of Japan, Hainan Island in China, Timol Leste, Australia, Ethiopia, France, and some individuals from Tsushima Island and Honshu of Japan. The divergence time between the two clades is estimated to be 0.86–1.89 Mya. The phylogenetic analysis revealed that Japanese L. migratoria populations were composed of individuals of six different origins: (1) Hokkaido populations possibly from the Russian continent; (2) Honshu–Kyushu populations from the Chinese continent; (3) Southwest Island populations from Hainan Island or adjacent areas; (4) Ogasawara populations that might have originated from Micronesia; (5) part of the Tsushima population that originated from somewhere in the Asian tropics; and (6) a possible relict population of ancient southern haplotypes that exists in western areas of northern Honshu. The Tsugaru Straits and Tokara Straits have acted as effective geographical barriers, as in other organisms, isolating locust populations for a few thousand years.

Environmental anomalies in the northeastern East China Sea during the last 3 000 years: implications for El Niño activity in the Holocene

To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS), biogenic compounds (such as carbonate, organic carbon and opal), marine micropaleontological fossils (planktonic foraminifera, benthic foraminifera, radiolarian and silicoflagellate) and the compositional characters of benthic foraminifera fauna analyses were carried out on a sediment core DOC082 obtained from the western slope of Okinawa Trough (29 degrees 13.93'N, 128 degrees 08.53' E; 1 128 m water depth). The long-term changes of biogenic and micropaleontological proxies display some similarities through the last 10 500 a, which show three different phases: lower values are recorded during the early and middle Holocene (before about 4 000 a BP), followed by an abrupt and remarkable increase at about 4 000 a BP, the late Holocene (after about 3 000 a BP) is characterized by continuously high values. The multi-proxy data of paleoproductivity and percents of benthic foraminifera genera (Uvigerina and Bulimina) show that during the early and middle Holocene (10 500-4 000 a BP) productivity was relatively low with a sudden and distinct increase at about 4 000 a BP, and the late Holocene (3 400-0 a BP) is marked by significantly higher productivity. Also, the radiolarian-based sea surface temperature (SST) records reveal a distinct decline in SST in the late Holocene after 3 200 a BP, very different from the early and middle Holocene. For the last 3 000 a, the enhanced biological productivity and distinctly lower SST indicate a major change of oceanographic conditions in the northeastern ECS. These marine environmental anomalies are consistent with other paleoclimatic records for the late Holocene in the Chinese continent and its surrounding regions. After analyzing the mechanisms of modern productivity and SST changes in the northeastern ECS, and based on the climatic anomalies in the Chinese continent and variations in the Kuroshio Current during modern El Nino periods, we suggest that the anomalous environmental conditions in the northeastern ECS may imply intensified El Nino activity during the late Holocene.

Origin and Transportation Course of Heavy Metal Elements in the Particulate Matter (PM) at the Hachimantai Mountain Range in Northern Japan

Particulate matter (PM) was collected at the Hachimantai mountain range in northern Japan. In the present study, the origin and transportation course of the heavy metal elements were discussed for PMfine and PMcoarse, determined by using PIXE (Particle Induced X-ray Emission) and back trajectory analyses. The result shows that the PMfine emitted mainly from artificial sources, compared with the PMcoarse from natural sources, since the Enrichment Factor (EF) value and S/K ratio of PMfine was one order higher than that of PMcoarse. The origin of Pb in PM at Akita Hachimantai mountain range has both of the anthropogenic and the metal refining origins, using the analysis of Pb/Br. Furthermore, from result of back trajectory analysis when the air mass was transported over the Japanese Islands, the air mass was mainly passed over the large-scale industrial area in Japan. The origin of As and Se were mainly gasoline and coal combustion, and were transported from Chinese continent and/or Korea peninsula. NMCC ANNUAL REPORT 16 (2009)

Accurate Correction Models for Tidal Gravity in Chinese Continent

AbstractAccurate correction models for tidal gravity in Chinese continent are developed by using the recent theoretical and experimental models for the Earth's tidal gravity, in which the loading effects of the global and local ocean tides are combined. The relative difference of tidal gravity variations induced from different Earth's tidal gravity models is less than 0.06%. The ocean tide loading effects are about 4% of the total tidal gravity in coastal area while they are about 1% in inland. The difference between the ocean tide loading effects estimated from global ocean tide models and modified global models with local tides is about 10% of the total ocean tide loading effects. And the interpolated and extrapolated ocean tide loading effects are about 3% of the total ones. Comparing the observed tidal gravity variations by superconducting gravimeter with the ones calculated through the correction models, it is confirmed that the models developed in this study can accurately predict the tidal gravity signatures with a precision much better than 0.5 × 10−8 m·s−2. Consequently, it is expected that the models should provide an effective reference and accurate correction models for gravity measurements.

A Study of Solar Eclipse Records during the Three Kingdoms Period in Korea

In this study, solar eclipse records were investigated during the Three Kingdoms era of ancient Korea using astronomical calculations and numerical simulations. Under the condition that the solar eclipses were actually observed at the well known capitals of the Three Kingdoms, I investigated the probabilities that the optimal observation areas of the Early Silla, Goguryeo, and Baekje records would appear around Chinese continent. I found higher probabilities than those suggested by Park and La (1994), although the numerical values are still low, especially in the case of the Early Silla records. On the other hand, the probability that the optimal observation area of the Later Silla records will be present around South Korea is only 13.6%, although the area shows a good match with the known capital. I also analyzed the number distribution of the eclipse records for the Three Kingdoms (except for the latter Silla's) according to the observers' locations: at the optimal observation areas and at the known capitals. And then I compared with the number distribution of all eclipses observable from those locations. From the <TEX>$\chi^2$</TEX>-test, I found that the Goguryeo and Baekje records had better representation of their population distributions at the latter regions (<TEX>$\chi^2$</TEX>=27.93 and 205.5) than at the former ones (<TEX>$\chi^2$</TEX>=34.19 and 211.5). Therefore, it is difficult to conclude that the observers' locations during the Three Kingdoms period were either near China, as suggested by Park and La, or in the Korean peninsula, solely based on these results. It is thus recommended that more studies are required to confirm the real observers' locations during the Three Kingdoms era.

Heat flow distribution in Chinese continent and its adjacent areas

Using a compilation of 6980 heat flow measurements, we produce a new heat flow map for the Chinese continent and its adjacent areas. We develop an objective and integrated method to interpolate the heat flow data, taking into account both the uniformity within geological units and coherency of regional heat flow. The geologic units are outlined based on Zhang et al.’s active tectonic block model. Our heat flow model is presented in two formats: a contour map and a heat flow dataset with values on a 1 × 1° grid for the Chinese continent and its adjacent areas, reflecting detailed variations in some regions. Also provided is a resolution map which helps understand the reliability of the heat flow model. Our results reveal that (1) Heat flows in the eastern part of the Chinese continent are relatively higher than those in the western part except that in the Tibetan Plateau area. (2) Heat flows in the Ordos and North China blocks are around 60 mW/m 2, and are 50–55 mW/m 2 in South China except for the continental marginal sea regions. (3) Heat flow is the lowest in the Junggar Basin, only 35–45 mW/m 2, and is 45–55 mW/m 2 in the Tarim Basin. The results of this study provide an important dataset for studies on thermal and rheological structures of the Chinese continent and its adjacent areas.

Numerical manifold method and its application in the study of crustal movements in the Sichuan-Yunnan Area

The numerical manifold method (NMM) can calculate the movements and deformations of structures or materials. Both the finite element method (FEM) for continua and the discontinuous deformation analysis (DDA) for block systems are special cases of NMM. NMM has separate mathematical covers and physical meshes: the mathematical covers define only fine or rough approximations; as the real material boundary, the physical mesh defines the integration fields. The mathematical covers are triangle units; the physical mesh includes the fault boundaries, joints, blocks and interfaces of different crust zones on the basis of a geological tectonic background. Aiming at the complex problem of continuous and discontinuous deformation across the Chinese continent, the numerical manifold method (NMM) is brought in to study crustal movement of the Sichuan-Yunnan area. Based on the GPS velocity field in the Sichuan-Yunnan area, a crustal strain and stress field is simulated and analyzed. Moreover, results show that the NMM is a more suitable method than DDA in simulating the movement of the Sichuan-Yunnan area. Finally, a kind of mechanism of crustal motion in the Sichuan-Yunnan area is discussed in the paper.

Estimation of vegetative mercury emissions in China

Vegetative mercury emissions were estimated within the framework of Biogenic Emission Inventory System (BEIS3 V3.11). In this estimation, the 19 categories of U.S. Geological Survey landcover data were incorporated to generate the vegetation-specific mercury emissions in a 81-km Lambert Conformal model grid covering the total Chinese continent. The surface temperature and cloud-corrected solar radiation from a Mesoscale Meteorological model (MM5) were retrieved and used for calculating the diurnal variation. The implemented emission factors were either evaluated from the measured mercury flux data for forest, agriculture and water, or assumed for other land fields without available flux data. Annual simulations using the MM5 data were performed to investigate the seasonal emission variation. From the sensitivity analysis using two sets of emission factors, the vegetative mercury emissions in China domain were estimated to range from a lower limit of 79 x 10(3) kg/year to an upper limit of 177 x 10(3) kg/year. The modeled vegetative emissions were mainly generated from the eastern and southern China. Using the estimated data, it is shown that mercury emissions from vegetation are comparable to that from anthropogenic sources during summer. However, the vegetative emissions decrease greatly during winter, leaving anthropogenic sources as the major sources of emission.

제주도 고산지역의 라돈 및 TSP 에어로졸 농도 특성: 2001&amp;#x007E;2004년 측정

The real-time monitoring of radon () concentrations has been carried out to evaluate its ambient background concentration levels in Gosan site, Jeju Island between January 2001 and December 2004. In addition, the atmospheric TSP aerosols have been sampled, and their ionic and metallic components were analyzed to understand the characteristics of air pollution. The mean concentration of radon was , and the seasonal mean concentrations for spring, summer, fall and winter seasons were 2,898, 2,398, 3,571 and , respectively, The hourly concentrations have shown the highest value at 7 a.m. and the lowest value at 2 p.m. From the backward trajectory analyses, the radon concentrations have increased, when the air parcels were moved from the Chinese continent to Jeju area. On the other hand, they have decreased, when the air parcels from the North Pacific Ocean. In the analytical results of ionic species and metal elements of TSP aerosols, the concentrations of and S were higher in June and March. Meanwhile, the concentrations of other anthropogenic species as well as soil components were mostly higher in March and April. On the basis of factor analysis, the TSP aerosols at Gosan area were largely influenced by soil sources, followed by anthropogenic sources and marine sources. From the result of backward trajectory analyses, the concentrations of , Al and Ca were mostly higher, when the air parcels moved from Chinese continent to Jeju area. On the other hand, their concentrations were lower, when the air parcels drifted from the North Pacific Ocean.

High 210Po atmospheric deposition flux in the subtropical coastal area of Japan

Bulk atmospheric deposition fluxes of 210Po and 210Pb were measured at three coastal regions of Japan, the Pacific Ocean coastal area of the Japanese mainland (Odawa Bay), the Chinese continental side of Japanese coastal area (Tsuyazaki), and an isolated island near Okinawa (Akajima). Wet and dry fallout collectors were continuously deployed from September 1997 through August 1998 for periods of 3 to 31 days depending on the frequency of precipitation events. Annual 210Pb deposition fluxes at Odawa Bay (35°N 139°E), Tsuyazaki (33°N 130°E) and Akajima (26°N 127°E) were 73.3 ± 8.0, 197 ± 35 and 78.5 ± 8.0 Bq m −2 y −1, respectively. Higher 210Pb deposition was observed at the Chinese continental side of Japanese coast than at the Pacific Ocean coastal site. The high 210Pb atmospheric flux at the Chinese continental side coast was thought to be attributable to 222Rn-rich air-mass transport from the Chinese continent during the winter monsoon. In contrast, the annual 210Po deposition fluxes at the three study sites were 13.0 ± 2.3 (Odawa Bay), 21.9 ± 4.4 (Tsuyazaki) and 58.4 ± 7.7 (Akajima) Bq m −2 y −1, respectively, indicating unusual high 210Po deposition at Akajima during winter. Anomalous unsupported 210Po input was observed during summer 1997, suggesting unknown source of 210Po at this area.

Molecular phylogenetic analysis of the infraspecific taxa of Erigeron thunbergii A. Gray distributed in ultramafic rock sites

AbstractWe aimed to determine the evolutionary patterns of plants, especially focusing on plants that occur in habitats composed of ultramafic rock. We carried out molecular phylogenetic analyses of the infraspecific taxa of Erigeron thunbergii composed of varieties and the closely related species Erigeron miyabeanus. Most of these plants are distributed in serpentine, peridotite, limestone, diabase and non‐ultramafic areas of high mountains, meadows and seashores in Japan. Using data derived from sequencing the internal transcribed spacer (ITS1, 5.8S ribosomal DNA and ITS2) regions of nuclear ribosomal DNA, we identified Clade 1, which was composed of populations from Hokkaido Island and the north‐east Honshu district group, and Clade 2, which was comprised of populations from central Honshu Island, Oga Peninsula and Mt Shokanbetsu. In addition, we identified three subclades within Clade 2 in detail. The phylogenetic tree showed the possibility of two major Erigeron phylogenies, that is, from the Kamchatka Peninsula and the Chinese continent. Moreover, the plants distributed in serpentine soils on Mt Yubari and in Shimukappu showed phylogenetically closer relationships than plants distributed in more closely located non‐ultramafic sites.

A Combination of Bulk and Single Particle Analyses for Asian Dust

A multi-stage particle sampling instrument and a particle counter were operated at the ground monitoring site in Fukuoka where was directly exposed to the outflow of air masses from the Asian continent during the springtime of 2005. The bulk and individual dust particles were analyzed simultaneously by ICP-MS and micro-PIXE, respectively. The ground-based observation of dust storm by the Japan Meteorological Agency and by the NOAA HYSPLIT dispersion-trajectory model indicated that dust storm was driven from the Chinese continent including dust source area. The number concentration of gigantic particles (e.g., larger than 5 μm) was measured to be 10 times higher in an Asian dust storm (hereafter called “ADS”) period than in a non-ADS period. There is an outstanding increase of mass concentration in the range of 3.5–7.7 μm in ADS event. In ADS event, soil fraction accounts 57.9–70.1% of particle mass concentration in coarse particles larger than 3.5 μm. Micro-PIXE analysis enables us to classify individual dust particles into several types. The particles with 3.5–5.1, 5.1–7.7, and 7.7–10.9 μm experienced aging processes by 60.6, 69.2, and 77.2%, respectively. On the basis of the reconstructed elemental maps by micro-PIXE analysis, the chemical transformation of dust particles was also presumed.