Dissolved organic phosphorus utilization and alkaline phosphatase activity of the dinoflagellate <Emphasis Type="Italic">Gymnodinium impudicum</Emphasis> isolated from the South Sea of Korea

This study investigated alkaline phosphatase (APase) activity and dissolved organic and inorganic phosphorus utilization by the harmful dinoflagellate Gymnodinium impudicum (Fraga et Bravo) Hansen et Moestrup isolated from the South Sea of Korea. Under conditions of limited phosphorus, observation of growth kinetics in batch culture yielded a maximum growth rate (μ_max) of 0.41 /day and a half saturation constant (Ks) of 0.71 μM. In time-course experiments, APase was induced as dissolved inorganic phosphorus (DIP) concentrations fell below 0.83 μM, a threshold near the estimated Ks; APase activity increased with further DIP depletion to a maximum of 0.70 pmol/cell/h in the senescent phase. Thus, Ks may be an important index of the threshold DIP concentration for APase induction. G. impudicum utilizes a wide variety of dissolved organic phosphorus compounds in addition to DIP. These results suggest that DIP limitation in the Southern Sea of Korea may have led to the spread of G. impudicum along with the harmful dinoflagellate Cochlodinium polykrikoides in recent years.     

Analytical and statistical approach for evaluating the effects of a river barrage on river–aquifer interactions

The construction of a river barrage can increase groundwater levels upstream of the barrage during the rainy season. Analytical and statistical approaches were applied to evaluate the relationship between groundwater and river water at the Changnyeong–Haman river barrage in Korea using time series data of water level and electrical conductivity from June 2011 to September 2014. An artificial neural network based time series model was designed to filter out the effect of rainfall from the groundwater level data in the study area. Aquifer diffusivity and river resistance were estimated from the analytical solution of a one‐dimensional unit step response function by using the filtered groundwater level data. River resistance increased in response to groundwater level fluctuations. Cross‐correlation analyses between the groundwater and the river water showed that the lag time increased during the observation period for both the water level and the electrical conductivity while the cross‐correlation function declined for the same period. The results indicated that a constant river stage maintained at the river barrage can weaken the hydrologic stress and reduce the exchange of material between the river and the adjacent aquifer because of the deposition of fine sediment on the river bottom and walls. Copyright © 2016 John Wiley & Sons, Ltd.     

A petrogenetic grid for eclogite and related facies under high-pressure metamorphism

The petrogenetic grid between the eclogite and other high-pressure/temperature (P/T) metamorphic facies in a basaltic system is constructed by considering barroisite as one of the important phases in high-P/T metamorphism and by using previous petrological data combined with Schreinemakers' analysis and slope calculation. In the constructed petrogenetic grid, the eclogite facies is bounded by the blueschist and epidote–amphibolite facies with negative-slope reactions at lower temperatures (450–550 °C) and by the epidote–amphibolite, amphibolite and granulite facies with positive-slope reactions at higher temperatures (> 550–600 °C). The eclogite facies does not contact the greenschist facies, and the lowest P condition for the eclogite facies exists at the boundary between the eclogite and epidote–amphibolite facies. The temperature range of the epidote–amphibolite facies increases with increasing pressure until 8–11 kbar and then decreases up to 13–15 kbar. Compared to boundaries of other facies, boundaries of the eclogite facies may have wider P–T ranges. The boundary between the blueschist and eclogite facies occurs over a large temperature range from 450 to 620 ± 30 °C, and the transitions between the eclogite and amphibolite or high-pressure granulite facies occur over a pressure range in excess of 6–10 kbar.     

Spatio-temporal distribution and characteristics of PAHs in sediments from Masan Bay, Korea

The distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in the surface and core sediments from Masan Bay, Korea. Total PAHs in the surface sediments ranged from 207 to 2670 ng/g dry weight with a mean value of 680 ng/g. Qualitative similarity and quantitative difference between inner and outer bay indicate that the main sources of PAHs are located in the inner bay and outer bay is also affected by the same sources. Vertical distribution of PAHs revealed that three distinctive stages could be differentiated with the help of PCA analysis. The highest concentration (industrialization stage) appeared between late 1950s and 1980, which was 10 years later than other developed countries. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources, and diagenetic PAH, perylene also contributed. Total organic carbon normalized PAHs (sum of 13 PAHs, 8.85-88.0 microg/g OC) were under the threshold effects concentration (TEC, 290 microg/g OC).     

Assessment of butyl- and phenyltin pollution in the coastal environment of Korea using mussels and oysters

Butyl- and phenyltin residues in bivalves were quantified around the coast of Korean peninsula in 1995–1998 and 2001. Butyltin compounds were detected at all the sites surveyed, whereas phenyltins were detected at 41 out of 67 sites in 1995–1998. Tributyltin (TBT) concentrations in bivalves ranged 48–2800 ng Sn/g on dry weight basis. Triphenyltin (TPT) concentrations ranged <3–1820. The mean TPT concentration was 3.5 times less than that of TBT. Spatial distribution of TBT was closely related to boating and dry-docking activities. TPT concentration in bivalves showed significant correlation with TBT. Concentrations of TBT in bivalves, 2001 are not significantly changed compared to those in 1995–1998. However, TPT concentrations in bivalves steeply decreased in 2001. High concentration of TBT and lesser extent TPT and their nation-wide distribution indicate that organotins are one of major organic pollutants in the marine environment of Korea.     

Seasonal characteristics of the near-surface circulation in the northern South China Sea obtained from satellite-tracked drifters

The surface circulation of northern South China Sea (hereafter SCS) for the period 1987–2005 was studied using the data of more than 500 satellite-tracked drifters and wind data from QuikSCAT. The mean flow directions in the northern SCS except the Luzon Strait (hereafter LS) during the periods October~March was southwestward, and April~September northeastward. A strong northwestward intrusion of the Kuroshio through the LS appears during the October~March period of northeasterly wind, but the intrusion became weak between April and September. When the strong intrusion occurred, the eddy kinetic energy (EKE) in the LS was 388 cm²/s² which was almost 2 times higher than that during the weak-intrusion season. The volume transport of the Kuroshio in the east of the Philippines shows an inverse relationship to that of the LS. There is a six-month phase shift between the two seasonal phenomena. The volume transport in the east of the Philippines shows its peak sis-month earlier faster than that of the LS. The strong Kuroshio intrusion is found to be also related to the seasonal variation of the wind stress curl generated by the northeasterly wind. The negative wind stress curl in the northern part of LS induces an anticyclonic flow, while the positive wind stress curl in the southern part of LS induces a cyclonic flow. The northwestward Kuroshio intrusion in the northern part of LS happened with larger negative wind stress curl, while the westward intrusion along 20.5°N in the center of the LS occurred with weaker negative wind stress curl.     

Can the Southern annular mode influence the Korean summer monsoon rainfall?

We demonstrate that a large-scale longitudinally symmetric global phenomenon in the Southern Hemisphere sub-polar region can transmit its influence over a remote local region of the Northern Hemisphere traveling more than 100° of latitudes (from ~70°S to ~40°N). This is illustrated by examining the relationship between the Southern Annular Mode (SAM) and the Korean Monsoon Rainfall (KMR) based on the data period 1983-2013. Results reveal that the May-June SAM (MJSAM) has a significant in-phase relationship with the subsequent KMR. A positive MJSAM is favorable for the summer monsoon rainfall over the Korean peninsula. The impact is relayed through the central Pacific Ocean. When a negative phase of MJSAM occurs, it gives rise to an anomalous meridional circulation in a longitudinally locked air-sea coupled system over the central Pacific that propagates from sub-polar to equatorial latitudes and is associated with the central Pacific warming. The ascending motion over the central Pacific descends over the Korean peninsula during peak-boreal summer resulting in weakening of monsoon rainfall. The opposite features prevail during a positive phase of SAM. Thus, the extreme modes of MJSAM could possibly serve as a predictor for ensuing Korean summer monsoon rainfall.     

The First Record of Long Headed Eagle Ray,Aetobatus flagellum (Pisces: Myliobatidae) from Korea

A specimen ofAetobatus flagellum was collected at Uljin in June 2005 for the first time in Korea. This specimen is characterized by the cephalic fin, the long snout, the dorsal fin between pelvic fins, spiracles on the dorsal side of the disc, the deeply notched nasal curtain and the one row of the teeth in the lower and the upper jaws. And unlikeAetobatus narinari, it does not have any spots on the its dorsal side of the disc. We report this specimen as the first record from Korea and name it ‘Bak-jui-ga-o-ri’ in Korean.