The Formation and Circulation of the Intermediate Water in the Japan Sea

In order to clarify the formation and circulation of the Japan/East Sea Intermediate Water (JESIW) and the Upper portion of the Japan Sea Proper Water (UJSPW), numerical experiments have been carried out using a 3-D ocean circulation model. The UJSPW is formed in the region southeast off Vladivostok between 41°N and 42°N west of 136°E. Taking the coastal orography near Vladivostok into account, the formation of the UJSPW results from the deep water convection in winter which is generated by the orchestration of fresh water supplied from the Amur River and saline water from the Tsushima Warm Current under very cold conditions. The UJSPW formed is advected by the current at depth near the bottom of the convection and penetrates into the layer below the JESIW. The origin of the JESIW is the low salinity coastal water along the Russian coast originated by the fresh water from the Amur River. The coastal low salinity water is advected by the current system in the northwestern Japan Sea and penetrates into the subsurface below the Tsushima Warm Current region forming a subsurface salinity minimum layer. This revised version was published online in August 2006 with corrections to the Cover Date.     

Collectorless flotation of chalcopyrite and sphalerite ores by using sodium sulfide

The flotation of chalcopyrite and sphalerite from copper and copper-zinc ores has been achieved without using thiol-type collectors. Typically, a sulfide ore sample is first treated with sodium sulfide either during grinding or during the preflotation conditioning period, and then the chalcopyrite is floated with frother alone. With a copper-zinc ore, sphalerite is subsequently floated from the chalcopyrite tailings by activating it with copper sulphate. Results of the collectorless flotation tests are comparable to those obtained by using thiol collectors. The mechanisms of selective collectorless flotation are discussed on the basis of differences in the solubilities of sulfide minerals.     

Abundance and distribution of Nemopilema nomurai (Scyphozoa,Rhizostomeae), in Korean waters in 2005–2013

Nemopilema nomurai have appeared massively since 2003 in Korean waters, and regular offshore monitoring has been performed since 2005 in the eastern Yellow Sea (YS), northwestern East China Sea (ECS), Korean southern waters (Ksw), and western East Sea (ES). Korea Jellyfish Monitoring Network (KoJEM) was established in 2006 for coastal jellyfish monitoring. From these, sight survey monitoring data were gathered and analyzed to extract the yearly and seasonal fluctuation of N. nomurai’s abundance and distribution. The first massive annual appearance of N. nomurai occurred in the northwestern ECS, off Shanghai, China, in mid May of 2005–2008 and of 2012–2013. In other years or concurrently with the appearance in the northwestern ECS in the same year, several individuals were found in the mid-eastern YS and Ksw, and southwestern ES. The population of N. nomurai at the northwestern ECS moved to the southeastern YS and Jeju Strait in June, and from the July to August it extended its distribution all around the Korean peninsula and persisted till October. Since October, the distribution was retracted into the southern YS and Ksw, and disappeared slowly. N. nomurai’s yearly abundance varied a lot, from nearly 0 inds 10^?4m^?2 in 2010 to 62.4 inds 10^?4m^?2 in 2005. The highest abundance was recorded in 2005, followed by 2007 and 2009, and the least abundance was in 2008 and 2010–2013. The results were compared with those of the Liaoning Bay, Bohai Sea, which led to speculation about a new seeding place of N. nomurai, and mortality during the early planktonic phase of N. nomurai was proposed as the determinant of the yearly variation in abundance.     

Particle shape effect on thermal conductivity and shear wave velocity in sands

This study presents the correlations between quantified shape parameters and geotechnical properties for nine sand specimens. Four shape parameters, sphericity, convexity, elongation and slenderness, were quantified with two-dimensional microscopic images with the aid of image processing techniques. An instrumented oedometer cell is used to measure compressibility, thermal conductivity and shear wave velocity during loading, unloading and reloading stages. As the particle shape inherently determines the initial loose packing condition, initial void ratio and shape parameters are well correlated with compressibility. The applied stress in soils increases the interparticle contact area and contact quality; round particles tend to achieve higher thermal conductivity and shear wave velocity during stress-induced volume change. Multiple linear regression is implemented to capture the relative contributions of involved variables, revealing that the thermal evolution is governed by the initial packing density and particle shape. The experimental observations underscore the predominant effect that particle shape has on the geomechanical and physical properties upon stress-induced soil behavior.     

Composition of the phytoplankton pigments in the surface waters along a transect from the Northwestern to the southeastern Pacific Ocean

Multidisciplinary oceanic investigation was undertaken in Aug–Sep. 2003 along a transect from Northwestern (Busan, Korea) to Southeastern Pacific (Talcahuano, Chile) to understand the physical, chemical and biological features in the surface water, and to depict their interaction with the atmosphere. Among the twenty parameters measured, we describe the physical, chemical and biological features. Physico-chemical data were analyzed in conjunction with the geographic position and yielded 7 peculiar surface water masses. The first water mass (28.4°N, 130.8°E to 21.5°N, 139.5°E) was warm and low in phosphate and nitrate content, and high in silicate. The concentration of phytoplankton pigment was one of the lowest. The second (20.4°N, 140.7°E to 2.2°S, 162.9°E) was the warmest and the least saline. Nitrate and phosphate concentration were one of the lowest. Chlorophyll a (Chl a) concentration was the lowest among the surface waters. The third (3.4°S, 164.0°E to 14.5°S, 173.3°E) was warm. Nitrate concentration was the lowest. CHL-a, peridinin (Perid), violaxanthin (Viola), zeaxanthin (Zea), chlorophyll-b (Chl b) and β-CAR were abundant. The fourth (18.6°S, 177.5°E to 31.8°S, 123.9°W) was saline and poor in nutrient concentration. The contributions of 19′-butanoyloxyfucoxanthin (But-fuco), 19′-hexanoyloxyfucoxanthin (Hex-fuco), and CHL b to CHL a were non-negligible. The fifth (32.4°S, 122.1°W to 33.8°S, 117.2°W) was relatively cold and well oxygenated. Concentration of Fuco, But-fuco, Hex-fuco and Chl b was high. The sixth (34.2°S, 115.4°W to 37.4°S, 92.1°W) was cold, well oxygenated and enriched with phosphate and nitrate. Concentration of phytoplankton pigment was, however, one of the lowest. The seventh, located off the Chilean coast, from 37.2°S, 87.2°W to 36.1°S, 74.1°W was well oxygenated and highly enriched with nitrate and phosphate. Phytoplankton pigments such as Fuco, Perid, But-fico, and Hex-fuco were rich. The 7 surface water masses are partially attributed to Kuroshio Current, North Equatorial Current and North Equatorial Countercurrent, South Equatorial current, South Pacific Subtropical Gyre, South Pacific Current, Subtropical Front and Chilean coastal water. The differences in physicochemical characteristics and the history of the surface water resulted in difference in quantity and composition of the phytoplankton pigment.     

East Asian monsoon variation and climate changes in Jeju Island, Korea, during the latest Pleistocene to early Holocene

A 4.96-m-long sediment core from the Hanon paleo-maar in Jeju Island, Korea was studied to investigate the paleoclimatic change and East Asian monsoon variations during the latest Pleistocene to early Holocene (23,000-9000 cal yr BP). High-resolution TOC content, magnetic susceptibility, and major element composition data indicate that Jeju Island experienced the coldest climate around 18,000 cal yr BP, which corresponds to the last glacial maximum (LGM). Further, these multi-proxy data show an abrupt shift in climatic regime from cold and arid to warm and humid conditions at around 14,000 cal yr BP, which represents the commencement of the last major deglaciation. After the last major deglaciation, the TOC content decreased from 13,300 to 12,000 cal yr BP and from 11,500 to 9800 cal yr BP, thereby reflecting the weakening of the summer monsoon. The LGM in Jeju Island occurred later in comparison with the Chinese Loess Plateau. Such a disparity in climatic change events between central China and Jeju Island appears to be caused by the asynchrony between the coldest temperature event and the minimum precipitation event in central China and by the buffering effect of the Pacific Ocean.     

Characteristics of tephra in Holocene lake sediments on King George Island, West Antarctica: implications for deglaciation and paleoenvironment

Several reworked tephra layers in gravity-flow deposits are present in lacustrine core sediments collected from Hotel and Rudy Lakes on King George Island, South Shetland Islands, maritime sub-Antarctica. This study tests the values of tephra for establishing regional tephrochronologies for lakes in ice-covered landscapes in the vicinity of volcanoes. The tephra record is more abundant in a long Hotel Lake core (515 cm long). This study uses volcanic glass samples from five tephra layers of Hotel Lake and from one tephra layer of Rudy Lake. Morphologically, tephras are mixtures of basaltic and pumice shards, both having various degrees of vesicularity. Major element analyses of glass shards reveal that the majority of the glass fragments belong to basic glass (<60 wt% SiO₂), compositionally ranging from basalt to low-silica andesite and subalkaline series medium-K tholeiites, probably sourced from Deception Island located 130 km southwest of King George Island. Less than 20% of tephra belongs to silicic glass and occurs in three tephra horizons E of Hotel Lake. However, source volcano(es) for about 10% of basic tephra and silicic tephra are not readily identified from nearby volcanic centers. Except for the studied tephra in Rudy Lake, all tephra samples in Hotel Lake are not ashfall deposits but reworked and redeposited pyroclasts derived from retreating ice sheet, resulting in the occurrence of geochemically equivalent tephra samples in different tephra horizons. The dating of the studied tephra horizons represents the timing of deglaciation rather than that of volcanic eruptions. The result of this study implies that combined with sedimentological information more chemical criterion is necessary to study tephrochronology and regional correlation and to understand paleoenvironmental changes using tephra.     

Cloning of cytochrome P450 1A (CYP1A) genes from the hermaphrodite fish Rivulus marmoratus and the Japanese medaka Oryzias latipes

To use two small fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and the Japanese medaka Oryzias latipes (Belloniformes) as testing models in molecular ecotoxicology, we have cloned the cytochrome P450 1A (CYP1A) gene after screening of both genomic DNA libraries, and sequenced 11,863 and 7,243 bp including all the exons and introns with promoter regions, respectively. The Rivulus and the medaka CYP1A gene consisted of seven exons (including non-coding exons) with high homology to mammals. In the promoter region, Rivulus CYP1A gene has seven xenobiotic response elements (XREs) and two metal response elements (MREs), while the Japanese medaka CYP1A gene has six XREs and four MREs. Interestingly, medaka CYP1A gene has a number of MREs at the promoter, which may affect its response on metal exposure. We describe here the gene structure of both fish CYP1A genes.     

Submarine groundwater discharge revealed by aerial thermal infrared imagery: a case study on Jeju Island,Korea

Submarine groundwater discharge (SGD) is a global phenomenon that carries large volumes of groundwater and dissolved chemical species such as nutrient, metals, and organic compounds to coastal zones. We report the influence of SGD on the coastal waters of Jeju Island, Korea, using high‐resolution aerial thermal infrared (TIR) mapping techniques and field investigations. An aircraft‐based system was implemented using a cost‐effective TIR camera for aerial TIR mapping. Ground‐based calibrations and system integration with GPS/IMU (global positioning system/inertial measurement unit) were performed for the aerial systems. The aerial surveys showed distinct low‐temperature signatures of SGD along the coasts of Jeju Island, revealing large groundwater inputs from the coastal aquifers to the ocean. Multiple aerial surveys over a range of seasons and tidal stages revealed that SGD rates dynamically affect the sea surface temperature (SST) of the coastal zone. The in‐situ measurements supported that SGD has a substantial influence on the coastal water chemistry as well as SST. Our observations highlight the extent to which aerial‐based TIR mapping can serve as a powerful tool for studying SGD and other coastal processes. Copyright © 2016 John Wiley & Sons, Ltd.     

Holocene and Eemian climatic optima in the Korean Peninsula based on textural and carbon isotopic records from the stalagmite of the Daeya Cave,South Korea

Textural and stable isotopic records from the absolute-dated stalagmite of the Daeya Cave (DY-1) provide new insights into the climatic evolution of the Korean Peninsula during the Holocene and Eemian climatic optima. The stalagmite yielded ages of 8572 ± 227 to 5907 ± 158 and 1,23,456 ± 535 to 1,19,837 ± 1089 years, which coincide with the Holocene and Eemian climatic optima, respectively. The stalagmite’s δ¹³C record closely resembles previously reported Chinese speleothem δ¹⁸O data. Thus it can be suggested that textural and geochemical results of the DY-1 reflect East Asian monsoon intensity, which is forced by summer insolation patterns in the northern hemisphere. Lighter carbon isotopic compositions, well-developed fibrous calcite crystals, and their relatively faster growth rate in the stalagmite sample are interpreted to reflect the warmest and wettest climate conditions of the Holocene and Eemian interglacials. Both climatic optima took place when insolation was decreasing from its maximum level, temperature in Greenland was highest, and sea level approached its maximum level. These climatic optima also coincide with decreasing Antarctic temperatures. Compared the DY-1 data to other proxies, it is suggested that the Holocene and Eemian climatic optima developed through a balance among boreal insolation, monsoon intensity, and sea level (also continental ice volume), which are the main climatic forcing factors in the northern hemisphere. These trends also follow the bi-polar seesaw mechanism as previously described.