Southeastern Part Of Korea Research Articles

Relationship between Clonorchis sinensis Infection and Cholangiocarcinoma in Korea.

This study provides an overview of the current status of clonorchiasis and cholangiocarcinoma (CCA), and their relationship in Korea during 2012–2020. Data were obtained from the Health Insurance Review & Assessment Service of Korea. Cluster, trend, and correlation analyses were performed. Gyeongsangnam-do and Seoul had the highest average number of cases (1,026 and 4,208) and adjusted rate (306 and 424) for clonorchiasis and CCA, respectively. The most likely clusters (MLC) for clonorchiasis and CCA were Busan/Gyeongsangnam-do/Ulsan/Daegu/Gyeongsangbuk-do (Relative Risk; RR=4.55, Likelihood Ratio; LLR=9,131.115) joint cluster and Seoul (RR=2.29, LLR=7,602.472), respectively. The MLC for clonorchiasis was in the southeastern part of Korea, while that for CCA was in the southern part. Clonorchiasis showed a decreasing trend in the southeastern districts, while increased in the southwestern districts. Cities in the central region had a decreasing trend, while the western districts had an increasing trend. In most adults (30–59), infection rate of clonorchiasis showed a significant decrease until 2018, while thereafter increased, although not significant. CCA showed a sharply decreasing tendency. The incidence of clonorchiasis and CCA were positively correlated. In general, the correlation was weak (r=0.39, P<0.001), but it was strongly positive around the 4 river basins (r=0.74, P<0.001). This study might provide an analytic basis for developing an effective system against clonorchiasis and CCA.

Invasion pathway of the honeybee pest, small hive beetle, Aethina tumida (Coleoptera: Nitidulidae) in the Republic of Korea inferred by mitochondrial DNA sequence analysis

Abstract The small hive beetle (SHB), Aethina tumida, is native to the Sub-Saharan region of Africa, but it became invasive in many countries after its first introduction to the USA in 1996. The SHB is a destructive pest of the honey industry and can cause damage in apiaries due to feeding on the honey, pollen, honey bee brood and honey fermentation. SHB was recently found infesting honeybee colonies in the South-Eastern part of Korea, Miryang city in 2016. No inference of the origin or the pathway of the invasion into Korea has been made, so far. We analyzed partial cytochrome oxidase I gene of mitochondrial DNA to unveil the possible source of the invasive populations of SHB in South Korea. A Bayesian inference tree and median joining haplotype network revealed a strong relationship between South Korean and North American populations suggesting that the SHB in South Korea came from the USA. Low genetic variation among Korean populations suggests that the invasion might have occurred in a single event with small number of founders. In addition, a new global distributional map of SHB is provided.

Mineralogical changes and distribution of heavy metals caused by the weathering of hydrothermally altered, pyrite-rich andesite

The weathering of pyrite-rich andesite in the southeastern part of Korea has led to acid rock drainage, creating severe environmental problems in the region. In this study, the mineral compositions and geochemical mobility of heavy metals in the bedrock, in addition to the weathering products, are investigated. Samples of bedrock and weathering products were collected from two sites in the Yangsan area. Site 2 shows considerably more weathering than site 1, due to the longer duration of weathering. The mineral compositions show that the bedrock at site 2 was more heavily altered by hydrothermal activity. The weathering products at site 2 contain jarosite and goethite with lower pH values than site 1, in which the samples are buffered by calcite. This indicates that the mineral compositions and pH values of the weathering products at the two sites are influenced by the primary mineral compositions of the bedrock and the duration of weathering. With the exception of Pb, the concentrations of heavy metals at site 1 are higher than those at site 2, probably due to higher concentrations in the bedrock. Moreover, the labile and acid-soluble fractions, which can be more readily released into the environment, are higher at site 1, mainly due to the shorter duration of weathering. Accordingly, the weathering process at site 1 carries more potential hazards to the environment than that at site 2. However, chemical weathering is locally impeded by calcite buffering at site 1. Although the concentrations of heavy metals at site 2 are lower than those at site 1, they are being continuously released due to the lower pH and longer and more and extensive weathering.

Prevalence and Clinical Impact of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Isolated From Hospitalized Patients.

BackgroundWe estimated the prevalence and clinical impact of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). The concordance between macromethod and glycopeptide resistance detection (GRD) E tests was determined. In addition, predictors of clinical outcomes in hospitalized patients with S. aureus bacteremia (SAB) or pneumonia (SAP) were evaluated.MethodsWe obtained 229 consecutive S. aureus isolates from all hospitalized patients at two university hospitals located in Busan and Yangsan, Korea. Standard, macromethod, and GRD E tests were performed. Additionally, we reviewed the medical records of all patients. Among the 229 patients, predictors of clinical outcomes were analyzed for 107 patients with SAB and 39 with SAP.ResultsAmong the 229 isolates, 34.5% of S. aureus isolates and 50.7% of methicillin-resistant S. aureus isolates exhibited the hVISA phenotype based on the macromethod E test. hVISA was nearly associated with treatment failure in patients with SAB (P=0.054) and was significantly associated with treatment failure in patients with SAP (P=0.014). However, hVISA was not associated with 30-day mortality in patients with SAB or SAP. The concordance between the macromethod and GRD E tests was 84.2%.ConclusionshVISA is quite common in the southeastern part of Korea. hVISA is associated with treatment failure in patients with SAP.

Areas vulnerable to natural disasters and damage estimation of infrastructure in Busan, Korea

Since the damages caused by disasters associated with climate anomalies and the diversification of the social structure increase every year, an efficient management system associated with a damage assessment of the areas vulnerable to disasters is demanded to prevent or mitigate the damages to infrastructure. The areas vulnerable to disasters in Busan, located at southeastern part of Korea, were estimated based on historical records of damages and a risk assessment of the infrastructure was performed to provide fundamental information prior to the establishment of the real-time monitoring system for infrastructure and establish disaster management system. The results are illustrated by using geographical information system (GIS) and provide the importance of the roadmap for comprehensive and specific strategy to manage natural disasters.

The Re-evaluation of the Potential Seismic Hazard in Relation to Nuclear Power Plants of Korea

본 연구에서 원자력발전소의 안전과 관련하여 한반도 남동부의 지진위험을 재평가하였다. 활단층과 쓰나미 발생과 같은 주요한 두가지 인자들을 지진위험연구에 고려했다. 본 연구에서 주요 지진위험의 재평가는 연안의 지형적 특성과 쓰나미 피해 관계를 포함해서 지진 메커니즘 분석과 활단층의 위치관계를 재결정하는 것이다. 또한 중력가속도(g)의 관점에서 지진 강진동과 규모사이의 기본적인 연관성은 원자력발전소의 내진설계를 위해 명확하게 설명되어야 한다는 것이다. 현재 국내에는 23개의 원자력발전소가 가동 중이며 향후 10년 이내에 훨씬 더 많은 원전이 건설될 것 이다. 하지만 한반도 남동쪽의 원자력발전소들이 위치한 지역에는 최근 지진활동인 포항지진(1981년 4월 5일, M=5.3)과 영월지진(1996년 12월 13일, <TEX>$M_W$</TEX>=4.8), 경주지진(1997년 6월 26일, <TEX>$M_W$</TEX>=4.7), 울진지진(2004년 5월 29일, M=5.2), 오대산지진(2006년 1월 20일, M=4.8)과 역사적으로 신라시대에 경주지역에는 수많은 지진이 발생하여 인명피해와 가옥의 손실을 가져왔다. 이와 같은 사실에 비추어 볼 때 더 이상 지진위험에서 안전하다고 말할 수 없다. 본 연구의 주요한 이유는 향후 도래할 지진으로부터 재난을 줄이기 위해서는 반드시 원자력발전소와 포화 상태에 놓인 원전 폐 연료와 관련한 모든 지진 위험의 재평가를 제안하는 것이다. The seismic hazard of the southeastern part of the Korean peninsula is re-evaluated in relation to safety of nuclear power plants. We take into account two main factors such as seismic hazard with active faults and tsunami occurrences. Major seismic hazard re-evaluation is performed by mechanism of earthquakes and relocation of active faults including tsunami phenomena. The basic relationship between an earthquake strong motion in terms of gravity (g) and magnitude is clearly demonstrated for an earthquake resistant design in nuclear power plants. At present we are operating 23 nuclear power plants and we will increase more nuclear power plants in the next decade. Nevertheless the nuclear power plants in the southeastern part of Korea are not free from seismic hazard in the light of recent seismicity - Pohang Earthquake on April 15, 1981 (M=5.3), Yeongwol Earthquake on December 13, 1996 (M=4.8), Gyeongju Earthquake on June 26, 1997 (M=4.7), Uljin Earthquake on May 29, 2004 (M=5.2) and Mt. Odae Earthquake on January 20, 2006 (M=4.8), including many large historical earthquakes in the Gyeongju area which gave severe damage to houses and loss of people in the Shilla Dynasty. The compelling reason of this study is to suggest the seismic hazard re-evaluation in relation to the over-saturated spent fuels as well as nuclear power plants in order to reduce the seismic disaster from the forthcoming earthquakes.

Effects of Fundamental Frequency and Duration Variation on the Perception of South Kyungsang Korean Tones

The perception of lexical tones is addressed through research on South Kyungsang Korean, spoken in the southeastern part of Korea. Based on an earlier production study (Chang, 2008a, 2008b), a categorization experiment was conducted to determine the perceptually salient aspects of the perceptual nature of a high tone and a rising tone. The experiment tested the perception of isolated synthetic stimuli, in which the crucial acoustic parameters (i.e., timing of F0 peak, initial F0, and syllable duration) were systematically manipulated. The results are generally consistent with the previous production data, showing that these acoustic cues contribute to the perception of two tones, a high tone and a rising tone. The stimulus tends to be identified as a rising tone if the F0 peak is late in the syllable, the initial F0 is low, and the syllable is long, while the stimulus tends to be identified as a high tone if the F0 peak is early in the syllable, the initial F0 is high, and the duration is short. Each of these three parameters, although necessary, did not contribute equally to the perception of tone contrast. Between-subject variation, according to the participant's gender and language background, is also discussed.

The Immersed Tunnel and Bridges of Busan– Geoje Fixed Link

The Busan–Geoje Fixed Link is a major infrastructure development in the south-eastern part of Korea and construction was completed in December 2010. The link provides easy access between metropolitan Busan city and Geoje Island. The Busan–Geoje Fixed Link has a total length of 8,2 km and comprises three major elements: two cable-stayed bridges (Lot 1 and Lot 2) and an immersed tunnel (Lot 3). The site location is an exposed offshore, which is subjected to strong winds, large swell waves and strong tidal currents. These conditions together with the tunnel being the deepest immersed tunnel ever built and the bridges being exposed to a high wind speed and the foundation condition consisting of a very soft, normally to slightly overconsolidated marine clay, made the project unique and one of the most challenging structures ever built.

우리나라 동남부 다모작 논토양의 경반화 특성

우리나라 남부 이모작 논토양의 생산성향상을 위한 합리적인 관리책을 제시코자 영남지역 주요 논 토양별 경반층 생성특성 및 원인을 현지조사 중심으로 수행한 결과는 다음과 같다. 논 토양의 배수등급 및 토성에 따라 총 90필지의 경운실태를 조사한 결과, 경운시기는 대부분 춘경이었고 기종은 중대형 트랙터가 대종을 이루고 있었으며 경운방법은 토양 배수조건이 불량할수록 위탁경운을 하는 경향이었다. 경운깊이와 원추관입 최대저항값 출현깊이와는 고도의 상관을 보였고, 최대저항값 출현 토심은 약 27.1 cm로 조립질 토양에서 다소 깊은 경향으로 원추관입최대저항값은 2.50 Mpa으로 사질 및 사양질 토성이 3.46~3.29 Mpa로 높았고, 경반층의 강도는 세립질토양에서 뚜렷이 높았다. 경반형성 부위의 용적중은 <TEX>$1.3{\sim}1.5g\;cm^{-3}$</TEX>로 미사질계 토양이 낮았으며 고상율은 사양질이 미사질에 비해 높아 공극율은 낮은 경향을 보였다. 경반층 직하토층의 유기물, 유효인산, 치환성칼리 함량은 표토에 비해 매우 낮은 경향인 반면, pH와 치환성 석회 및 고토의 함량은 높은 경향이었다. 토층별 토양수분 함량과 원추관입저항값과는 관계는 표토는 부의 상관을 보인 반면 심토는 일정한 경향이 없었다. 경운여부에 따른 논토양 원추관입저항은 토심 20~23 cm에서 큰 차이를 보였고 경운답은 2.03~2.21Mpa인 반면, 무경운답은 1.18~1.25 Mpa로 낮았으며 무경 운 년수가 진행될수록 쟁기바닥층은 없어지는 반면, 토심10 cm 부위에 원추관입저항이 높은 토층이 새로 생성되었음. 따라서 남부 다모작지 논토양 견밀화 (경반화) 토층은 토심 15~20 cm 부위에서 주로 형성되었으며 농작업과 관련성이 높으며 작업 시 토양의 수분조건은 경반화에 크게 영향하며 경반이 생성된 토층의 투수력은 <TEX>$0.03{\sim}0.14mL\;hr^{-1}$</TEX> 매우 낮아 양 수분의 수직이동에 영향을 미치는 것으로 나타났다. This study was carried out for some survey about soil compaction in the multi-cropping system of paddy field. Investigated sites were 90 farmer's fields in south-eastern part of Korea. The tillage practices season was different according to cropping system of paddy; in spring for mono rice cultivation and in autumn for the multi-cropping field. The average tillage depth in investigated sites was about 25 cm, however, it is different between the farmer's tillage practices and soil characteristics. It is high correlation to tillage deep and minimum resistance of penetration. The reaching soil deep to maximum resistance of penetration was about 27 cm, and average penetration resistance of the deep is 1.8~2.0 MPa for moderately fine-textured soils and more than 3.0 MPa for moderately coarse-textured soils. The difference of penetration resistance between cultivating and compacted layer was in order to sandy loam > clayey loam > clayey, and the difference was lesser in poorly drained soils than somewhat poorly ones. In the rice mono cropping field, the maximum resistance in no-tillage for 15 years was 1.18~1.25 Mpa at 20~25 cm in soil deep, however, the resistance of field with every year tillage practices was 2.03~2.21 Mpa. In the extremely compacted sandy loam textured soils, the penetration resistance at 30 cm in soil depth was drastically reduced by the subsoil from 5.2 Mpa to 3.2 Mpa, and the watermelon root in plastic film house was deep elongated.

Effects of morpheme boundaries on the timing of fundamental frequency (F0) peaks.

This research examines the effects of morpheme boundaries on the timing of fundamental frequency (f0) peaks and demonstrates that phonetic realization is influenced by morphological structure. It reports the timing of f0 peak and peak plateau in monomorphemic HH (high, high tone) and HL (high, low tone) as well as bimorphemic H+H and H+L in South Kyungsang Korean, spoken in the southeastern part of Korea. The results show that f0 peak came significantly later in bimorphemic H+H than in monomorphemic HH and peak plateau was significantly longer for monomorphemic HH than for bimorphemic H+H. It suggests that f0 peak plateau is implemented more stably within a single lexical item than across a boundary between lexical items. However, a significant morpheme effect was not found in monomorphemic HL and bimorphemic H+L. In accounting for these asymmetrical results, several hypotheses were discussed including speakers hyperspeech effort [H&H theory, Lindblom (1990)], intrinsic vowel height on f0 [Hombert et al. (1979)], and f0 peak delay effect on phonologically suggested H tone spreading [de Jong and McDonough (1993)]. It is proposed that the bimorphemic H+H in this language is the phonetic image of the f0 peak delay effect of high tone.

The effect of weak tone on the f0 peak alignment.

The f0 peak sometimes occurs after the syllable with which it is associated, and the peak alignment varies, depending on several factors such as lexical tone target, neighboring tones, focus, and so forth. This study investigates the effect of weak tones on the alignment of f0 peaks with three tone types (i.e., H, M, and R) of South Kyungsang Korean, spoken in the southeastern part of Korea. When three tone types are followed by one or two unstressed suffixes, R was found to have the maximum amount of peak delay and M was found to have the minimum amount, i.e., the peak came in the second syllable, following the R‐toned syllable, but the peak came in the syllable following the H‐toned syllable. This peak delay was not found for M. Thus, it is argued that the tone alternation patterns in suffixed words are not random; rather, they systematically reflect the phonetic implementation of each tonal target. For example, the peak is in the final portion of a syllable in R, and it takes more time for the peak to be fully realized. This effect can be clearly observed when the following tone is weak.

Stratigraphy, chronology and implied uplift rate of coastal terraces in the southeastern part of Korea

Terrace stratigraphy of the southeastern coastal areas of Korea has been studied with the help of terrace mapping and geochronology. Coastal terraces include 90–130 m upper High Terrace (uHT), 63–86 m High Terrace (HT), 36–55 m Middle Terrace (MT) and 8–25 m Low Terrace (LT) divisions, each of which has been subdivided. Amongst these, LT 2 formed during the late Pleistocene, based on Tephras Aso-4 (MIS 5c), Ata (MIS 5d or 5e) and OSL ages. The age of LT 1–3 ranges from MIS 5e to 5a, based on tephra ages from Aso-4 (ca. 90 ka) and Ata (100–125 ka). The uplift rate in the SE part of Korea ranges between 0.14 and 0.22 mm/a and it is quite small in comparison to the Japanese island arc, or many other tectonically active East and Southeastern Asian regions.

Weight-sensitive tone patterns in loanwords of south kyungsang korean

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Occurrence and Detection of Rice black-streaked dwarf virus in Korea

Until now, occurrence of Rice black-streaked dwarf virus (RBSDV) is observed in Gyeongsang provinces, southeastern part of Korea. However, recently, the occurrence of RBSDV is increasing and spreading in Jeonra provinces including Gochang-gun, southwestern part of Korea. RBSDV infected plants showed typical symptoms including stunted, deformed leaves with white waxy or black-streaked swelling along the veins. We extracted viral genomic dsRNA from infected leaves and analyzed dsRNA pattern by polyacrylamide gel electrophoresis. Ten genomic segments with similar sized dsRNAs were observed. We also detected RBSDV by reverse transcription (RT)-PCR using specific primers for S10 from genomic dsRNA and observed amplified DNA fragment specific for RBSDV S10.

Factors influencing natural occurrence of fluoride-rich groundwaters: a case study in the southeastern part of the Korean Peninsula

Factors regulating the occurrence of fluoride in groundwater were investigated using natural isotope tracers and geochemical data in the southeastern part of Korea where about 10% of the total public water-supply wells ( n = 422) inspected in this study had fluoride levels exceeding the drinking water limit of Korea (1.5 mg/l). The F-rich public wells are mostly distributed along the major faults, especially in the terrain of the F-rich granitic rocks. The stable isotope analysis results provide substantial information for the relative ages of groundwaters. It is revealed that the F-rich groundwaters are deeply circulating paleogroundwaters and occur along the faults due to upward flow along the fault plane. While reacting with granitic rocks for a prolonged period, the F concentrations of groundwater are continuously enriched even after the groundwater reaches an equilibrium state with respect to fluorite (CaF 2) due to removal of Ca by precipitation of calcite (CaCO 3). These observations reflect that rock chemistry, groundwater age, well depth, and geologic structure are the important factors controlling the occurrence of high F groundwaters. However, high F groundwaters are rarely observed in the fault zones where the associated fractures are widely developed. Isotopic signature provides an evidence for deep penetration of recently recharged groundwater into the wide fault zone, indicating that the hydrologic condition of the fault is also an important factor controlling the occurrence of high F groundwaters.

Contamination of Tributyltin in Sediment from Four Bays in the Southeastern Part of Korea

Spatial and vertical variations of butyltins(BTs) were investigated in polluted sediments from Jinhae, Busan, Ulsan and Yeongil Bays located in the southeastern part of Korea. Tributyltin(TBT) as a dominant species was detected in 18 of the 20 surficial sediments, and TBT levels were lower that for those in heavily polluted areas worldwide, ranging from 12 to 766 ng Sn/g dry wt. Distribution of TBT levels among bays was not significantly different (p=0.286, ANOVA). The horizontal distributions observed at 20 sites suggests that TBT concentrations are still high in polluted sites around harbors and industrial complexes. The sedimentary records a peak in the early 1990s in Jinhae Bay, in the mid 1980s in Ulsan Bay and in the late 1970s in Yeongil Bay except for Busan Bay which had a homogenous profile. In paricular, TBT at the surface sediments of four core samples still had high levels. From the horizontal and vertical results, it could be assumed that TBT inputs in the sediments were not reduced significantly compared to past levels. The annual accumulation rates estimated using the sedimentation rates and the concentration of surficial sediments exhibited that the accumulation rate of Ulsan Bay was greater than the rates for Jinhae and Yeongil Bays.

Estimation of Critical Loads of. Sulfur and Nitrogen for the Korean Ecosystem

The critical loads of sulfur and nitrogen and their exceedances by the sulfur and nitrogen deposition of 1994-1998 were mapped for South Korea for the first time with a spatial resolution of 11km×14km (0.12 5° Long.×0.125° Lat.) using the steady-state mass balance model. The Korean soil and geological maps with the map scale of 1: 250, 000 and the Korean forestry statistical yearbooks were used as basis for the estimations of weathering rate of base cations, critical alkalinity leaching, denitrification fraction and uptakes of base cation and nitrogen. Wet depositions of sulfur, nitrogen and non-sea-salt base cations were derived from measured concentrations in precipitation and precipitation rates using optimum regression equations while dry depositions of sulfur and base cations were estimated using the inferential method. However, dry deposition of nitrogen due to NO, NO2, NH3 and NH4+ species was estimated using the MM5 numerical model, a modified Regional Acid deposition Model (RADM) and the K-mean clustering technique using three consecutive days of gridded daily mean 850 hPa geopotential height fields without precipitation on the last day over South Korea for 5 years. The predominant ranges of base cation deposition, weathering and uptake were estimated to be 300-500 eq ha-1 yr-1, 200-500 eq ha-1 yr-1 and 200-400 eq ha-1 yr-1, respectively. Critical alkalinity leaching was mainly in the range of 1, 0002, 000 eq ha-1 yr-1. Consequently, a large percentage of the maximum critical load of sulfur was found to be in the range of 1, 0002, 000 eq ha-1 yr-1. The estimated predominant ranges of nitrogen immobilization and uptake were 120-180 eq ha-1 yr-1 and 300-400 eq ha-1 yr-1, respectively, indicating low values of the minimum critical load of nitrogen. The maximum critical load of nitrogen was found to be relatively high (predominantly 2, 0004, 000 eq ha-1 yr-1) while the critical load of nutrient nitrogen was low (predominantly 400-800 eq ha-1 yr-1). Exceedance of the maximum critical load of sulfur was found at 85% of the Korean ecosystems considered mainly in the southeastern part of Korea, whereas that of the critical load of nutrient nitrogen was found in the whole Korean ecosystems. This implies that Korean ecosystems are very susceptible to the combined loadings of sulfur and nitrogen.

Characteristics of Clay Minerals in Gouges of the Dongrae Fault, Southeastern Korea, and Implications for Fault Activity

AbstractThe Dongrae fault within the Yangsan fault system is considered one of the major faults in the southeastern part of Korea, extending over 150 km. The results of K-Ar radiogenic dating of fault gouges collected from six localities show a relatively wide range in age from 57.5 million years ago (Ma) to 40.3 Ma. Fault gouges are composed of newly formed minerals, including smectite, illite, zeolite, kaolinite, K-rich feldspar, apatite, and pyrite. The occurrence of abundant smectite and illite-lMd with lesser quantities of zeolite suggests that the fault gouges experienced hydrothermal alteration at low temperatures. Smectite is probably unstable relative to other clay minerals, such as illite and zeolite. Considering that filiform mordenite is replacing the smectite, we suggest that mordenite formed by recrystallization involving a solid-state transformation. Under high fluid/rock ratios, smectite seems to have formed in the early stage of alteration. In contrast, zeolite minerals and authigenic K-rich feldspar progressively appeared with time as the fluid/rock ratio decreased with the changing chemistry of the hydrothermal fluids. The composition of clay minerals in the gouge materials probably was controlled by the chemistry and the amount of circulating fluids derived from adjacent granitic rocks.

Estimation of sulfur deposition in South Korea

Dry and wet depositions of sulfur have been estimated using the routinely available meteorological data at 70 sites, air-monitored data at 27 sites and upper air soundings made daily twice (0000 and 1200 UTC) at three stations over South Korea for 4 yr from 1994 to 1997. The average annual total dry deposition and wet deposition of sulfur in South Korea are found to be 3 and 1.7 t km −2 yr −1, respectively. The ratio of dry-to-wet deposition of sulfur is found to vary with season with a maximum value of 6.6 in winter to a minimum value of 0.5 in summer in association with both precipitation amount and SO 2 concentration. The maximum of annual total sulfur deposition exceeding 10 t km −2 yr −1 occurs in the southeastern part of Korea where big cities and industrial complexes are located, suggesting the importance of SO 2 emission for deposition of sulfur.

Petrogenesis of the Tertiary volcanic rocks from the southeastern part of Korea.

Several episodes of magmatic activity recorded within the Tertiary sedimentary basins in the southeastern part of Korea are interpreted to have formed in a framework of separation of Japan arc from Eurasia. The volcanic rocks are Early Eocene or Early-Middle Miocene in age, showing a distinct chronological gap. The Miocene volcanics are regionally divided into two groups along the Hyeongsan fault; younger Daljeon basalts (13.6-15.2 Ma, K-Ar age) within the Pohang basin, north of the fault, and older volcanics (16-22 Ma) within the Janggi, Eoil and Haseo basins, south of the fault. The Daljeon basalts contain olivine as a major phenocryst, and are alkalic, ne-normative, trachy basaltic, “Within Plate Basalt”-like and enriched in incompatible elements. The older volcanics have plagioclase as a major phenocryst, and are subalkalic, q-normative, andesitic, “Arc Basalt”-like, and depleted in incompatible element. 87Sr/86Sr and 143Nd/144Nd ratios of the younger basalts are 0.7044-0.7045 and 0.512831-0.512835, respectively, whereas those of the older andesitic rocks are 0.7041-0.7048 and 0.512643-0.512809, respectively. Sm/Nd and Rb/Sr ratios of the basalts 0.154-0.158 and 0.026-0.034 whereas those of the andesitic rocks are 0.013-0.298 and 0.052-0.123, respectively. Of the andesitic rocks, samples of the Eoil basin are more refractory. Campared with available data, the Daljeon basalts are geochemically and isotopically similar to Enriched mantle type ocean island basalt (OIBs) or worldwide intraplate alkaline basalts, whereas the andesitic rocks are similar to those from the andesites of the Andes, South America. Overall characteristics suggest that source magma of the Daljeon basalts may be derived from upwelling asthenospheric magma with additional fractional crystallization. On the other hand, genesis of the andesitic rocks can be explained through a complex history at an active continental margin. Some geochemical differences among the andesitic rocks may be explained with different degrees of fractional crystallization and heterogeneity of initial source compositions. Based on the separation history of the Japan arc from Eurasia, magmatism of the Tertiary sedimentary basins can be explained by andesitic succeeded by alkali basaltic activity, after intermittent cessation of subduction due to changes of plate motion.