Chemical weathering of carbonates and silicates in the Han River basin,South Korea     

Jong-Sik Ryu  Kwang-Sik Lee  Ho-Wan Chang  Hyung Seon Shin 《Chemical Geology》2008,247(1-2):66-80

A detailed investigation of the fluvial geochemistry of the Han River system allows to estimate the rates of chemical weathering and the consumption of CO₂. The Han River drains approximately 26,000 km² and is the largest river system in South Korea in terms of both water discharge and total river length. It consists of two major tributaries: the North Han River (NHR) and the South Han River (SHR). Distinct differences in basin lithology (silicate vs. carbonate) between the NHR and SHR provide a good natural laboratory in which to examine weathering processes and the influence of basin geology on water quality. The concentrations of major elements and the Sr isotopic compositions were obtained from 58 samples collected in both summer and winter along the Han River system in both 2000 and 2006. The concentrations of dissolved loads differed considerably between the NHR and SHR; compared with the SHR, the NHR had much lower total dissolved solids (TDS), Sr, and major ion concentrations but a higher Si concentration and ⁸⁷Sr/⁸⁶Sr ratio. A forward model showed that the dissolved loads in the NHR came primarily from silicate weathering (55 ± 11%), with a relatively small portion from carbonates (30 ± 14%), whereas the main contribution to the dissolved loads in the SHR was carbonate weathering (82 ± 3%), with only 11 ± 4% from silicates. These results are consistent with the different lithologies of the two drainage basins: silicate rocks in the NHR versus carbonate rocks in the SHR. Sulfuric acid derived from sulfide dissolution in coal-containing sedimentary strata has played an important role in carbonate weathering in the SHR basin, unlike in the NHR basin. The silicate weathering rate (SWR) was similar between the NHR and SHR basins, but the rate of CO₂ consumption in the SHR basin was lower than in the NHR basin due to an important role of sulfuric acid derived from pyrite oxidation.  相似文献   

Landslide susceptibility analysis using GIS and artificial neural network     

Saro Lee  Joo‐Hyung Ryu  Kyungduck Min  Joong‐Sun Won 《地球表面变化过程与地形》2003,28(12):1361-1376

The purpose of this study is to develop landslide susceptibility analysis techniques using an arti?cial neural network and to apply the newly developed techniques to the study area of Yongin in Korea. Landslide locations were identi?ed in the study area from interpretation of aerial photographs, ?eld survey data, and a spatial database of the topography, soil type and timber cover. The landslide‐related factors (slope, curvature, soil texture, soil drainage, soil effective thickness, timber age, and timber diameter) were extracted from the spatial database. Using those factors, landslide susceptibility was analysed by arti?cial neural network methods. The landslide susceptibility index was calculated by the back‐propagation method, which is a type of arti?cial neural network method, and the susceptibility map was made with a geographic information system (GIS) program. The results of the landslide susceptibility analysis were veri?ed using landslide location data. The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide location. A GIS was used to ef?ciently analyse the vast amount of data, and an arti?cial neural network to be an effective tool to maintain precision and accuracy. The results can be used to reduce hazards associated with landslides and to plan land use and construction. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Tectonic elements with South China affinity in the Korean Peninsula: new Early Jurassic palaeomagnetic data   总被引：1，自引：0，他引：1  

Koji Uno  Tae Woo Chang  Kuniyuki Furukawa 《Geophysical Journal International》2004,158(2):446-456

  相似文献   

Metagenomic approach revealed effects of forest thinning on bacterial communities in the forest soil of Mt. Janggunbong,South Korea     

Byeong-Ju Lee  Soo Hyung Eo 《山地科学学报》2018,15(1):59-67

The soil microbiome that plays important ecological roles in mountains and forests is influenced by anthropogenic and natural causes. Human activity, particularly harvesting or thinning, affects the soil microbiome in forests by altering environmental conditions, such as vegetation, microclimate, and soil physicochemical properties. The purpose of this study was to investigate the effects on forest thinning on the diversity and composition of the soil bacterial community. From next-generation sequencing results of the 16S rRNA gene, we examined differences in soil bacterial diversity and community composition before and after thinning at Mt. Janggunbong, South Korea. We identified 40 phyla, 103 classes, 192 orders, 412 families, 947 genera, and 3,145 species from the soil samples. Acidobacteria and Proteobacteria were the most dominant bacterial phyla in the forest soil of Mt. Janggunbong. Soil bacterial diversity measures (richness, Shannon diversity index, and evenness) at the phylum level increased after thinning, whereas species-level taxonomic richness decreased after thinning. Thinning provided new opportunities for bacterial species in Chloroflexi, Verrucomicrobia, Nitrospirae, and other nondominant bacterial taxa, especially for those not found in Mt. Janggunbong before thinning, to settle and adapt to the changing environment. Our results suggested that thinning affected the diversity and composition of soil bacterial communities in forests and mountains.  相似文献   

Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants     

YOUNGJOO HONG  DONGYEOB KIM  SANGJUN IM 《Journal of Earth System Science》2016,125(3):499-506

Wind erosion causes serious problems and considerable threat in most regions of the world. Vegetation on the ground has an important role in controlling wind erosion by covering soil surface and absorbing wind momentum. A set of wind tunnel experiments was performed to quantitatively examine the effect of canopy structure on wind movement. Artificial plastic vegetations with different porosity and canopy shape were introduced as the model canopy. Normalized roughness length (Z ₀/H) and shear velocity ratio (R) were analyzed as a function of roughness density (λ). Experiments showed that Z ₀/H increases and R decreases as λ reaches a maximum value, λ _max, while the values of Z ₀/H and R showed little change with λ value beyond as λ _max.  相似文献   

朝鲜半岛古元古代摩天岭群的碎屑锆石U-Pb年龄及其地质意义   总被引：2，自引：1，他引：1  

廖鑫  张晓晖  金胜贤  朴雄  郑哲寿 《岩石学报》2016,32(10):2981-2992

克拉通内部活动带变质沉积建造蕴藏了早期超大陆形成中地体聚-散动力学过程的重要信息,碎屑锆石年代学则是揭示这种信息的最佳工具之一。针对华北(中-朝)克拉通最具代表性的古元古代活动带(辽-吉-朝活动带)中巨量沉积建造精细表征方面的空白区域,本文开展了朝鲜半岛检德地区摩天岭群的碎屑锆石年代学研究。SIMS U-Pb定年结果显示,北大川组变火山碎屑岩样品的锆石年龄谱记录了约2.53Ga的主要年龄峰值和约2.19Ga的最年轻峰值,说明北大川组开始沉积的时代应该晚于2.2Ga。南大川组变沉积岩样品碎屑锆石记录的最年轻峰值年龄为约2.02Ga,说明南大川组的沉积时代应该不早于2.02Ga;其锆石年龄谱记录了一个主要年龄峰值区域(2.02~2.18Ga)、一个次要年龄峰值(约2.46Ga)和一些2.78~3.30 Ga的古老年龄,指示其物质源区主要为同区古元古代地质体和邻近地体上的太古宙变质基底。区域对比表明,摩天岭群与中国境内辽吉活动带中的辽河群及集安群/老岭群具有基本一致的碎屑锆石年龄谱,说明它们不仅是同一时代的产物,而且分享类似的物质源区。这些时代一致、物源相近的沉积建造可以为甄别古元古代辽-吉-朝活动带的大地构造属性提供重要参考。与沉积年龄相近的碎屑锆石占据主导的碎屑锆石年龄谱反映了汇聚板块边缘各类盆地的典型特征,而相悖于大部分碎屑锆石年龄远大于地层沉积年龄的裂谷型盆地。  相似文献   

朝鲜~19亿年侵入岩的岩石类型与构造背景初探   总被引：5，自引：5，他引：0  

彭澎  王冲  杨正赫  金正男 《岩石学报》2016,32(10):2993-3018

朝鲜半岛北部广泛发育~19亿年侵入岩,这些岩浆岩可以分为三个系列,分别为似斑状花岗岩系列(多为I型,以妙香山岩体为代表,年龄1900~1840Ma)、S型花岗岩系列(以嘉山岩体为代表,本文获得1862±5Ma锆石U-Pb年龄)和正长岩系列(以龙浦岩体为代表,本文获得1857±2Ma锆石U-Pb年龄)。似斑状花岗岩系列(I型花岗岩)大致对应朝鲜地质学家定义的Myohyangsan(妙香山)杂岩,以发育钾长石巨斑为特征,与麻粒岩相变质的火山岩-沉积岩系关系密切;S型花岗岩系列大致对应Ryonhwasan(莲花山)杂岩,以发育石榴石和堇青石等矿物为特征,与麻粒岩相变质的副变质岩共生:这说明前者可能与变质火山岩系相关,而后者可能和副变质岩相关。正长岩系列,朝鲜地质学家称为Sakju(朔州)杂岩,分布较为局限,仅见于朔州以及博川-定州之间,也见于邻区辽东,多为岩株。这三个系列岩浆岩稍早或者同期于角闪岩相-麻粒岩相变质(本文获得甑山"群"变质锆石U-Pb年龄1844±2Ma)。邻区辽东-吉南及胶东地区也发育这三个系列岩浆岩,但这两个地区~21亿年岩浆作用更为广泛。朝鲜半岛南部发育大量同期岩浆岩,但岩石类型以似斑状花岗岩为主,并发育紫苏花岗岩和斜长岩。我们推测,朝鲜半岛南北两侧基底属性存在差异,可能对应不同的古陆(华北与华南古陆)。综合分析表明,朝鲜~19亿年前广泛发育I型和S型花岗岩,并有幔源岩浆作用,同时发育正长岩类,并且这些岩浆活动与区域高级变质作用时代接近。考虑到本区存在太古宙基底,我们推测本区在古元古代可能处于类似现今活动大陆边缘弧背景。  相似文献   

朝鲜半岛平南盆地中元古代岩浆事件   总被引：4，自引：2，他引：2  

朴贤旭  翟明国  杨正赫  金正男  郑哲珠  吴福元  金胜贤  韩龙渊  朴雄  金明哲  侯泉林 《岩石学报》2016,32(10):3033-3044

朝鲜平南盆地翁津地区发育中元古代黄海群和同时期(称之为瓮津期)花岗岩,花岗岩体侵入于黄海群。本文采用锆石原位微区U-Pb定年技术,对黄海群中的酸性火山岩及花岗岩进行了年龄测试。获得的数据表明,黄海群中下部层位及上部层位的酸性火山岩分别在1235±5Ma和1203±7Ma喷发,由此说明黄海群的沉积时代应为中元古代,而不是传统上认为的古元古代;两个翁津期花岗岩体(翁津和黄衣山岩体)的侵位年龄分别为1251±22Ma和1248±13Ma,为中元古代花岗质岩浆活动的产物。上述1251~1203Ma年龄的获得,表明朝鲜半岛发育中元古代岩浆作用,从而明确朝鲜黄海裂谷与华北东缘裂谷在时间上具有同期性,同时也表明中国华北与朝鲜在中元古代具有类似的发展历史。  相似文献   

Quality control methods for KOOS operational sea surface temperature products     

YANG Chansu  KIM Sunhwa 《海洋学报(英文版)》2016,35(2):11-18

Sea surface temperature SST obtained from the initial version of the Korea Operational Oceanographic System(KOOS) SST satellite have low accuracy during summer and daytime. This is attributed to the diurnal warming effect. Error estimation of SST data must be carried out to use the real-time forecasting numerical model of the KOOS. This study suggests two quality control methods for the KOOS SST system. To minimize the diurnal warming effect, SSTs of areas where wind speed is higher than 5 m/s were used. Depending on the wind threshold value, KOOS SST data for August 2014 were reduced by 0.15°C. Errors in SST data are considered to be a combination of random, sampling, and bias errors. To estimate bias error, the standard deviation of bias between KOOS SSTs and climatology SSTs were used. KOOS SST data yielded an analysis error standard deviation value similar to OSTIA and NOAA NCDC(OISST) data. The KOOS SST shows lower random and sampling errors with increasing number of observations using six satellite datasets. In further studies, the proposed quality control methods for the KOOS SST system will be applied through more long-term case studies and comparisons with other SST systems.  相似文献   

Latitudinal change in benthic foraminiferal fauna by ITCZ movement along the ~131°W transect in the equatorial Pacific Ocean     

Hiroyuki Takata  Chan Min Yoo  Hyung Jeek Kim  Boo-Keun Khim 《Ocean Science Journal》2016,51(4):655-663

Modern and fossil benthic foraminifera were examined from nine surface sediments and two piston cores along the ~131°W transect in the equatorial Pacific Ocean. This study was conducted to clarify the biotic response of abyssal benthic foraminifera during the last 220 ka to changes in the seasonal extent of the Intertropical Convergence Zone (ITCZ). The abundance of modern benthic foraminifera was high at stations between the equator and 6°N, whereas it was low at stations north of 6°N, which is generally consistent with the latitudinal CaCO₃ distribution of surface sediments. The northward increase of Epistominella exigua from the equator to ~6°N is similar to the seasonal variations in chlorophyll-a concentrations in the surface water and ITCZ position along ~131°W. This species was more common at core PC5103 (~6°N) than at core PC5101 (~2°N) after ~130 ka, when the Shannon-Wiener diversity (H’) between the two cores started to diverge. Hence, the presentday latitudinal difference in benthic foraminifera (E. exigua and species diversity) between ~2°N and ~6°N along ~131°W has been generally established since ~130 ka. According to the modern relationship between the seasonality of primary production and seasonal ITCZ variations in the northern margin of the ITCZ, the latitudinal divergence of benthic foraminiferal fauna between ~2°N and ~6°N since ~130 ka appear to have been induced by more distinct variations in the seasonal movement of ITCZ.  相似文献